Fight Aging!

The Alzheimer's disease research community is nowadays ever more strongly considering chronic inflammation in the brain as a vital part of the progression of the condition. In the amyloid cascade hypothesis, a slow aggregation of amyloid-β over decades (for reasons that are debated) causes ever greater inflammatory dysfunction in microglia, the immune cells of the brain responsible for clearing up metabolic waste such as protein aggregates. That inflammation in turn sets the stage for tau aggregation to take place to a significant degree, causing cell death and severe neural dysfunction.

Today's open access research is an example of the sort of work taking place to better understand how amyloid-β interacts with microglia to produce the outcome of chronic inflammation. In principle at least, a better understanding usually leads to new targets for the development of drugs that can interfere in the process.

A great deal of hypothesizing takes place among Alzheimer's researchers. The animal models are highly artificial, and thus prone to misleading results, there is a great deal of dissatisfaction with the decades-long relentless focus on amyloid-β, and it is very costly to prove any particular point using human data and human patients. Theorizing is thus a great deal easier than validating any given hypothesis, and as a result there are are numerous variations on the basic idea that chronic inflammation is an important part of the progression of Alzheimer's disease. One faction sees rising levels of amyloid-β as only a side-effect of persistent infections (such as herpesvirus, lyme disease, and so forth), and it is the infection that produces lasting inflammation in brain tissue, and its downstream consequences. Another faction ties the new understanding of cellular senescence into the development of chronic inflammation in the brain. In the years ahead, these various views will eventually give way to a true understanding, as the state of the human evidence improves.

Alzheimer's disease: Inflammation triggers fatal cycle

Alzheimer's disease is characterized by clumps of the protein Aß (amyloid beta), which form large plaques in the brain. Aß resembles molecules on the surface of some bacteria. Over many millions of years, organisms have therefore developed defense mechanisms against such structures. These mechanisms are genetically determined and therefore belong to the so-called innate immune system. They usually result in certain scavenger cells absorbing and digesting the molecule.

In the brain, the microglia cells take over this role. In doing so, however, they trigger a devastating process that appears to be largely responsible for the development of dementia. On contact with Aß, certain molecule complexes, the inflammasomes, become active in the microglia cells. They then resemble a wheel with enzymes on the outside. These can activate immune messengers and thereby trigger an inflammation by directing additional immune cells to the site of action.

"Sometimes the microglia cells perish during this process. Then they release activated inflammasomes into their environment, the ASC specks." These released specks take on a calamitous dual role: On the one hand, they bind to the Aß proteins and make their degradation more difficult. On the other hand, they activate the inflammasomes in even more microglia cells, and much more than Aß alone would do. During this process, more and more ASC specks are released. It thus adds fuel to the fire, as it were, and thereby permanently stokes up the inflammation.

β-Amyloid Clustering around ASC Fibrils Boosts Its Toxicity in Microglia

Alzheimer's disease is the world's most common neurodegenerative disorder. It is associated with neuroinflammation involving activation of microglia by β-amyloid (Aβ) deposits. Based on previous studies showing apoptosis-associated speck-like protein containing a CARD (ASC) binding and cross-seeding extracellular Aβ, we investigate the propagation of ASC between primary microglia and the effects of ASC-Aβ composites on microglial inflammasomes and function. Indeed, ASC released by a pyroptotic cell can be functionally built into the neighboring microglia NOD-like receptor protein (NLRP3) inflammasome. Compared with protein-only application, exposure to ASC-Aβ composites amplifies the proinflammatory response, resulting in pyroptotic cell death, setting free functional ASC and inducing a feedforward stimulating vicious cycle. Clustering around ASC fibrils also compromises clearance of Aβ by microglia. Together, these data enable a closer look at the turning point from acute to chronic Aβ-related neuroinflammation through formation of ASC-Aβ composites.

Mesenchymal stem cell therapies vary widely in their ability to influence regeneration, though they fairly reliably reduce chronic inflammation in older patients. One challenge is that there is no standard on what constitutes a mesenchymal stem cell; it is a category so broad as to be almost meaningless. Further, two clinics performing what is ostensibly the same protocol using cells from the same source can produce widely divergent outcomes. In most cases, near all transplanted cells die, and the benefits obtained for the patient derive from signaling produced by the stem cells in the short period of survival following transplantation. A large fraction of this signaling is carried by extracellular vesicles, and since these vesicles can be harvested and used for therapy more readily than is the case for cells, many researchers and clinicians are turning their focus towards vesicle-based treatments.

Surprisingly, patients inoculated with mesenchymal stem cells (MSCs) to promote tissue regeneration showed less than 1% of such cells in the damaged tissue after 1 week. Yet, paradoxically, such strategy has produced positive results in the treatment of several pathologies, favoring tissue regeneration and functionality. Therefore, it has been suggested that the regenerative effect of the MSC is not mainly due to their capacity to proliferate and differentiate into the required cellular types in the damaged tissue. Instead, their main functionality would stem from their paracrine actions, through the production of different factors.

Interestingly, such hypothesis is supported by several studies, demonstrating that conditioned media from MSC cultures have a similar regenerative capacity - or even higher - than the MSC themselves. For instance, that has been demonstrated in rodent models of acute myocardial infarction. These results demonstrate the surprising therapeutic relevance of the MSC secretome. In view of these results, it has been proposed to rename such stem cells as "medicinal signaling cells."

The secretome of the MSC has one free fraction, made of soluble factors and metabolites, as well as other encapsulated into microvesicles (MV), to which the extracellular vesicles (EV) belong. Interestingly, it has been found that the latter is the main responsible for the therapeutic properties of the conditioned media from MSC cultures. This way, those EV can regulate different physiological processes, like cellular proliferation, differentiation, and migration. The therapeutic features of the MSC EV are mainly due to their immunomodulatory and immunosuppressive activities.

The use of EVs in therapy has relevant advantages, in relation to MSCs. Among them are the following: (i) can be isolated and stored at low temperatures, until needed, without requiring the production of large amounts of cells at the time of inoculation, which is needed for cellular therapy; (ii) their contents are encapsulated and protected from degradation in vivo (preventing some of the problems associated with small soluble molecules, such as cytokines, growth factors, transcription factors, and RNA, which are rapidly degraded); (iii) are quite stable, exhibiting a long average life; (iv) can be intravenously injected, reaching distant places, since the vesicles are small and circulate readily, whereas the MSC are too large, and thus may have difficulty circulating through thin capillaries; (v) can pass through the blood-brain barrier; and (vi) have reduced risks of unwanted side-effects, such as immune rejection.

Link: https://doi.org/10.3389/fbioe.2020.00146

Researchers here identify miR-155-5p as a potential target to improve mitochondrial function. This microRNA is upregulated with age, and appears to inhibit mitochondrial fission. That in turn prevents the cellular maintenance process of mitophagy from clearing out worn and damaged mitochondria efficiently enough to prevent loss of function. Since mitochondria provide the chemical energy store molecules that power all cellular operations, this has downstream consequences on cell and tissue function, including higher levels of cellular senescence.

Aging impairs the functions of human mesenchymal stem cells (MSCs), thereby severely reducing their beneficial effects on myocardial infarction (MI). MicroRNAs (miRNAs) play crucial roles in regulating the senescence of MSCs; however, the underlying mechanisms remain unclear. Here, we investigated the significance of miR-155-5p in regulating MSC senescence and whether inhibition of miR-155-5p could rejuvenate aged MSCs (AMSCs) to enhance their therapeutic efficacy for MI.

Young MSCs (YMSCs) and AMSCs were isolated from young and aged donors, respectively. The cellular senescence of MSCs was evaluated by senescence-associated β-galactosidase (SA-β-gal) staining. Compared with YMSCs, AMSCs exhibited increased cellular senescence as evidenced by increased SA-β-gal activity and decreased proliferative capacity and paracrine effects. The expression of miR-155-5p was much higher in both serum and MSCs from aged donors than young donors. Upregulation of miR-155-5p in YMSCs led to increased cellular senescence, whereas downregulation of miR-155-5p decreased AMSC senescence. Mechanistically, miR-155-5p inhibited mitochondrial fission and increased mitochondrial fusion in MSCs via the AMPK signaling pathway, thereby resulting in cellular senescence by repressing the expression of Cab39. These effects were partially reversed by treatment with AMPK activator or mitofusin2-specific siRNA.

By enhancing angiogenesis and promoting cell survival, transplantation of anti-miR-155-5p-AMSCs led to improved cardiac function in an aged mouse model of MI compared with transplantation of AMSCs. In summary, our study shows that miR-155-5p mediates MSC senescence by regulating the Cab39/AMPK signaling pathway and miR-155-5p is a novel target to rejuvenate AMSCs and enhance their cardioprotective effects.

Link: https://doi.org/10.1111/acel.13128

Identification of genetic variants associated with specific conditions has been a going concern for some time, but the creation of large national databases of genetic and biometric data in a number of countries has greatly expanded this area of study. In today's research materials, scientists demonstrate one way in which this can be used, as a confirmation of the importance of hypertension and obesity in present variations in human life expectancy. People with genetic variants that increase the odds of suffering either of these conditions tend to live shorter lives, something that also shows up in standard epidemiological studies.

Why is this the case? Hypertension, chronically increased blood pressure, results from the stiffening of blood vessels due to various low-level processes of cell and tissue damage. Cross-links that reduce elasticity in blood vessel walls, inflammation resulting from senescent cells, and so forth. The resulting increase in blood pressure leads to an acceleration of atherosclerosis, and pressure damage to delicate tissues in the kidneys, brain, and elsewhere. This is very harmful to organ function over the long term, as illustrated by the fact that even forcing a reduction in blood pressure, overriding regulatory mechanisms without addressing the underlying causes of the problem, can reduce mortality in old people.

The excess visceral fat of obesity, on the other hand, can be argued to accelerate the aging process by generating excessive numbers of senescent cells. This and other mechanisms in visceral fat tissue lead to greater levels of chronic inflammation, which in turn accelerates the development and progression of all of the common age-related conditions. Epidemiological studies suggest that any excess weight is harmful, but outright obesity is in the same ballpark as smoking when it comes to negative effects on health and life expectancy.

It's in our genome: Uncovering clues to longevity from human genetics

Part of DNA is composed of genes, of which proteins are produced that participate in virtually every process within our cells and organs. While variations in the genetic code determine biological traits, such as eye color, blood type, and risk for diseases, it is often a group of numerous variations with tiny effects that influence a phenotypic trait. Harnessing a huge amount of genetic and clinical data worldwide and a methodological breakthrough, it is now possible to identify individuals at several-fold increased risk of human diseases using genetic information.

Researchers have discovered that individuals who have a genetic susceptibility to certain traits, such as high blood pressure or obesity, have a shorter lifespan. To achieve their goal, the researchers analyzed genetic and clinical information of 700,000 individuals from biobanks in the UK, Finland and Japan. From these data, the researchers calculated polygenic risk scores, which are an estimate of genetic susceptibility to a biological trait, such as a risk for disease, to find out which risk factor causally influences lifespan.

The researchers found that high blood pressure and obesity were the two strongest risk factors that reduced lifespan of the current generation. Interestingly, while high blood pressure decreased lifespan across all populations the researchers investigated, obesity significantly reduced lifespan in individuals with European ancestry, suggesting that the Japanese population was somehow protected from the detrimental effects obesity has on lifespan.

Trans-biobank analysis with 676,000 individuals elucidates the association of polygenic risk scores of complex traits with human lifespan

While polygenic risk scores (PRSs) are poised to be translated into clinical practice through prediction of inborn health risks, a strategy to utilize genetics to prioritize modifiable risk factors driving heath outcome is warranted. To this end, we investigated the association of the genetic susceptibility to complex traits with human lifespan in collaboration with three worldwide biobanks (n = 675,898; BioBank Japan, UK Biobank, and FinnGen). In contrast to observational studies, in which discerning the cause-and-effect can be difficult, PRSs could help to identify the driver biomarkers affecting human lifespan.

A high systolic blood pressure PRS was trans-ethnically associated with a shorter lifespan (hazard ratio = 1.03) and parental lifespan (hazard ratio = 1.06). The obesity PRS showed distinct effects on lifespan in Japanese and European individuals. The causal effect of blood pressure and obesity on lifespan was further supported by Mendelian randomization studies. Beyond genotype-phenotype associations, our trans-biobank study offers a new value of PRSs in prioritization of risk factors that could be potential targets of medical treatment to improve population health.

The cellular housekeeping mechanisms of autophagy act to recycle proteins and structures within the cell. Upregulation of autophagy appears to be a crucial part of the reason why the response to mild stresses - such as heat, cold, lack of nutrients, and toxins - can actually improve cell and tissue function. Certainly the practice of calorie restriction relies upon functional autophagy in order to extend healthy life span. Researchers here note that autophagy is important in the maintenance of the many stem cell populations throughout the body that are required for ongoing tissue maintenance. The characteristic impairment of autophagy in later life, taking place for reasons that are only partially explored, may make a sizable contribution to the loss of stem cell function that also takes place with aging.

Autophagy is a fundamental cell survival mechanism that allows cells to adapt to metabolic stress through the degradation and recycling of intracellular components to generate macromolecular precursors and produce energy. The autophagy pathway is critical for development, maintaining cellular and tissue homeostasis, as well as immunity and prevention of human disease. Defects in autophagy have been attributed to cancer, neurodegeneration, muscle and heart disease, infectious disease, as well as aging. While autophagy has classically been viewed as a passive quality control and general house-keeping mechanism, emerging evidence demonstrates that autophagy is an active process that regulates the metabolic status of the cell.

Adult stem cells, which are long-lived cells that possess the unique ability to self-renew and differentiate into specialized cells throughout the body, have distinct metabolic requirements. Research in a variety of stem cell types have established that autophagy plays critical roles in stem cell quiescence, activation, differentiation, and self-renew. While it appears that targeting autophagy to inhibit the autophagy-mediated cell survival properties in cancer stem cells may hold promise for anti-cancer therapy, the importance of autophagy in maintaining normal stem cell function suggest that inducing autophagy may have therapeutic potential for regenerative medicine. Certainly within the context of aging, stimulation of autophagy via genetic and pharmacological approaches in aged stem cells have improved their regenerative capacity and function.

Link: https://doi.org/10.3389/fcell.2020.00138

Chimeric antigen receptor T cell therapies have done well in the treatment of leukemias, and are being adapted for use with cancers that form solid tumors. A patient's own cells are engineered to bear a new synthetic receptor that matches a specific protein on the surface of cancerous cells, which encourages an effective immune response against the cancer. As researchers discuss here, an alternative to the continued use of T cells of the adaptive immune system is to apply chimeric antigen receptors to macrophages of the innate immune system instead.

Chimeric antigen receptor (CAR) T cell therapy has been a game-changer for blood cancers but has faced challenges in targeting solid tumors. Now researchers may have an alternative to T cell therapy that can overcome those challenges. Their research shows genetically engineering macrophages - an immune cell that eats invaders in the body - could be the key to unlocking cellular therapies that effectively target solid tumors. The approach in this study is closely related to CAR T cell therapy, in which patient immune cells are engineered to fight cancer, but it has some key differences. Most importantly, it centers around macrophages, which eat invading cells rather than targeting them for destruction the way T cells do.

Macrophages also have another key difference from T cells in that they are the body's first responders to viral infections. This has historically presented challenges in trying to engineer them to attack cancer, since macrophages are resistant to infection by the standard viral vectors used in gene and cell therapy. In fact, this anti-viral property carried another unexpected benefit. Macrophages are generally among the first cells to be drawn in by cancer, and they are exploited to help tumors instead of eating them. However, the research team showed that when the viral vector is inserted, not only do these engineered macrophages express the CAR, they also transform into highly inflammatory cells. This transformation allows macrophages to resist being co-opted by tumors. Researchers say CAR macrophages may also be able to stimulate the rest of the immune system as they attack, potentially opening the door to a greater immune response.

Link: https://www.pennmedicine.org/news/news-releases/2020/march/car-macrophages-go-beyond-t-cells-to-fight-solid-tumors

Macrophages are cells of the innate immune system, found throughout the body, and which play a great many roles beyond the obvious ones of defending against invading pathogens. They destroy cancerous and senescent cells, ingest molecular waste and debris between cells, and participate in the processes of tissue regeneration and maintenance, to pick a few examples. Further, the immune system of the brain includes an analogous population of cells known as microglia, which additionally take on supporting roles essential to the proper functioning of neurons and their synaptic connections.

Chronic inflammation is important in the progression of age-related diseases, and as a part of the immune system macrophages are very much involved in inflammation. This is a two-way street; greater inflammatory signaling in the environment will tend to make macrophages adopt a more aggressive behavior, adding their own inflammatory signaling to the mix. Equally, macrophages that become inflammatory for other reasons can rouse greater and broader inflammation via their actions. This is particularly true for senescent microglia, which appear quite important in a number of age-related conditions.

Setting aside cellular senescence, macrophage behavior can be loosely divided into phenotypes known as polarizations. M1 macrophages are inflammatory and focused on attacking pathogens, while M2 macrophages are anti-inflammatory and focused on regeneration. This is a useful categorization, while recognizing that it perhaps oversimplifies the reality of a continuous distribution of behaviors, not a pair of widely separate states. Some aspects of aging are associated with a shift in populations to favor M1 over M2, but this is not universal. Nonetheless, a number of research groups are working to find ways to bias macrophages to one polarization over another, to turn their contribution from harmful to helpful.

Targeting Macrophages: Friends or Foes in Disease?

Macrophages occupy a prominent position during immune responses. They are considered the final effectors of any given immune response since they can be activated by a wide range of surface ligands and cytokines to acquire a continuum of functional states. Macrophages are involved in tissue homeostasis and in the promotion or resolution of inflammatory responses, causing tissue damage or helping in tissue repair.

Knowledge in macrophage polarization has significantly increased in the last decade. Biomarkers, functions, and metabolic states associated with macrophage polarization status have been defined both in murine and human models. Moreover, a large body of evidence demonstrated that macrophage status is a dynamic process that can be modified. Macrophages orchestrate virtually all major diseases - sepsis, infection, chronic inflammatory diseases (rheumatoid arthritis), neurodegenerative disease, and cancer - and thus they represent attractive therapeutic targets. In fact, the possibility to "reprogram" macrophage status is considered as a promising strategy for designing novel therapies.

Macrophages are widely distributed throughout the tissues and display a huge functional heterogeneity. They can acquire pro- or anti-inflammatory functions depending on the surrounding cytokines and tissue microenvironment. Macrophages have been classified according to a linear scale, on which M1 macrophages represent one extreme and M2 macrophages represent the other.

Macrophage polarization is plastic and reversible. While M1 polarization takes place at the initial stages of the inflammatory response, M2 polarization is predominant during resolution of inflammation. The sequential occurrence of both polarization states is an absolute requirement for the appropriate termination of inflammatory responses, as well as for adequate tissue repair after injury, and alterations in the shift between macrophage polarization states result in chronic inflammatory pathologies, autoimmune diseases, and even metabolic disorders. We believe that targeting macrophage polarization might lead to novel intervention strategies.

At some point in the future, clinical trials for therapies that target mechanisms of aging must start to assess the outcome on aging, rather than the present situation in which regulators force potentially broad rejuvenation therapies - such as senolytics - to address only one specific age-related condition at a time. The authors of this paper argue that this will be a challenging transition for present regulatory and research institutions, and that a great deal more use of computational modelling of aging and the effects of interventions will be needed to smooth the way. I agree that the regulatory system is a barrier and a roadblock to the paths that should be taken; I'm not sure that I agree with the specific recommendations made in this paper. Greater effective use of computational modelling should, in principle, allow cost reductions across the board in the development of therapies, but I don't know that this really changes the nature of the problem beyond reducing the expense of efforts made to solve it.

The conventional paradigm "one disease, one drug" should be updated to achieve the vision of targeting aging as a common component of human diseases. The current deterministic genetic paradigm of diagnosing and treating each separate age-related disease fails to fit with the broader anti-aging strategies aimed to address the closely related concepts of healthspan, resilience, and lifespan, which should be therapeutically managed in the absence of discrete, targetable genetic drivers of aging progression. Perhaps more importantly, current frameworks cannot capture the stochastic aspects that drive the shared trade-offs of the emerging strategies for organismal healthspan and rejuvenation, namely tissue-repair/wound-healing impairment and tumorigenesis.

Successful clinical trials with new families of candidate interventions targeting the biologic machinery of aging per se would be groundbreaking; delaying, preventing (or even reversing) the aging process would result in tremendous cost savings for healthcare systems while increasing the productive contributions that could be made by the older members of our societies. By modeling and predicting the behavior of interventions that target the aging hallmarks in both long-term and acute settings, defined by extension of healthspan/lifespan and enhanced resilience to acute stressors (i.e., reduced frailty), respectively, robust and standardized approaches such as stochastic biomathematical platforms would have the ability to sidestep most of the current challenges in aging-targeting clinical trials, to accelerate the achievement of optimum health and life quality in aging populations.

Link: https://doi.org/10.18632/aging.102180

Age-related changes in gut microbe populations provide an important contribution to the chronic inflammation that is characteristic of old age. Beneficial species diminish in number, reducing the production of metabolites that aid in optimal cell and tissue function. Harmful species increase in number, interacting with tissue and the immune system in ways that promote chronic inflammation. Practical approaches to reverse the age-related changes observed in the gut microbiome could be realized quite soon, given the will and funding: some form of fecal microbiota transplant, or intense probiotic treatment, perhaps. The former has been demonstrated to work in animals, improving health and extending life, and is already practiced for human patients in the medical community in order to treat certain conditions in which pathological bacteria have contaminated the gut.

Numerous studies have suggested that the composition of the gut microbiota differs between obese and normal weight individuals. However, the cause-effect relationship between obesity and gut microbiota composition is not yet fully understood. This study investigated the short-term responses of the gut microbiota composition to diets with different fat contents. Experimental animals were fed either a a normal diet (ND) or a high-fat diet (HFD) for 20 weeks and the microbial composition was evaluated at 10 and 20 weeks. In agreement with previous studies, body weight and the expression of colonic cytokines increased with higher dietary fat content. The diversity of the gut microbiota was significantly influenced by both age and diet, and two variable showed significant interactions.

At the phylum level, the proportion of Actinobacteria was significantly associated with dietary fat content, while the proportions of Firmicutes and Bacteroidetes were strongly associated with age. In the present study, a HFD significantly elevated the proportions of the phylum Actinobacteria and the class Actinobacteria_c in a positive association with body weight, which have also been shown to be increased in obese subjects and patients with type 2 diabetes.

A growing body of evidence suggests that a HFD increases gut permeability and endotoxemia, resulting in low-grade inflammation and impairment of the gut barrier. Given that bacteria in the phylum Actinobacteria are known as mucin-degrading bacteria, abundant Actinobacteria might be associated with gut barrier impairment induced by a HFD. Indeed, we observed that Actinobacteria was inversely related with tight junction proteins such as E-cadherin and positively associated with proinflammatory cytokines. Therefore, the HFD-mediated increase in Actinobacteria and Actinobacteria_c may play a role in the HFD-induced impairment of the intestinal barrier, leading to colonic inflammation.

We also found that in the phylum Actinobacteria, the class Coriobacteriia and the family Coriobacteriaceae were positively correlated with body weight and proinflammatory cytokines, while the change in the proportions of these bacteria was significantly associated with age. Although the mechanistic effects of age on the Coriobacteriaceae are unknown, it is positively associated with both ROS and inflammatory cytokines, which contribute to metabolic dysfunction.

Link: https://doi.org/10.1186/s12866-019-1557-9

I had quite forgotten about the video of this short commentary I'd given last year at Giant Health in London. I was recently prompted for a transcript by someone, and so here it is. This conference was a mainstream health event, not normally a place that would have any great focus on longevity and aging. However, the Aikora Health principals had claimed one of the stages and put together a set of presentations from various people involved in the development of means to treat aging, myself included. All of us were ambushed by interviewers with cameras at some point in the proceedings, and hence this video.

Longevity research and gene therapy: where are we now?

Certainly this event is an example of some of the people in our longevity community coming in and just taking over a little bit of somebody else's conference to talk about longevity ... but really exposing the rest of the community to it. I'm finding that at every event I go to, I'd really love to have conference presentations where I get to talk about some interesting thing about the longevity industry, because there are a lot of really interesting things going on.

But every presentation turns out to be "hey, we exist, please notice us - because this is really, really important." Everything that you guys think that you are doing in medicine is about to be up-ended, because suddenly we're going to be actually able to stop people from getting sick and incapacitated and debilitated in old age. This is happening right now, the first rejuvenation therapies exist. But nobody notices.

It is that interesting, weird stage of development where a thing has happened, but not everybody yet realizes that it has happened, and there is an awful lot of advocacy still needed to shove this great idea down everyone's throats, make them pay attention. That in fact, actually, yes, 50% of everyone with arthritis in old age probably do not need to have arthritis. They could go take a $100 senolytic drug combination and it would go away. This is news to you, and it is news to most people here. It needs to not be news and people need to get on and do this.

Since I run a gene therapy company, it is nice to see a whole gene therapy stage talk about that topic. Gene therapy is very much a wave. When we started Repair Biotechnologies, before we even knew what we were going to do, we said "this will be a gene therapy company." This is because it is self-evidently the case that a lot of small molecule development is going to go away and be replaced by gene therapy. Gene therapy is more precise, you can do more with it, and it is definitely easier to evolve a gene therapy program than a small molecule program. So this part of the field is really important, and it is really important that more people get out and talk about this.

The gut microbiome changes with age in ways that provoke chronic inflammation. Beneficial microbial populations decline in number while harmful populations expand. This is likely the result of numerous contributing factors, including dietary changes characteristic of age and the decline of the immune system, but at this point it is a challenge to pin down which of these processes are more versus less important to the overall outcome. It is well known that chronic inflammation drives a faster progression of many of the common age-related diseases, including neurodegenerative conditions. Thus it is expected to find links between the gut microbiome and conditions such as Alzheimer's disease, as is discussed here.

Factors that may be involved in the development of Alzheimer's disease are thought to include lifestyle habits. Lifestyle dysregulation may not only lead to Alzheimer's disease, but also to various other health problems such as dysregulation of the gut microbiota. The composition of symbiotic microorganisms has changed dramatically throughout human history with the development of agriculture, industrialization, and globalization. It is postulated that each of these lifestyle changes resulted in a gradual disappearance of microbial diversity and an increase in their virulence, thus causing the formation of a risk path for Alzheimer's disease pathogenesis. Changes in the microbial composition throughout history suggest an escalation of the risk of Alzheimer's disease.

Recent advances in research on the etiology of Alzheimer's disease suggest that microbiota (oral, nasal, intestinal) dysbiosis during life can lead to a systemic inflammatory response and affect microglia immune response in the brain. More and more experimental and clinical data confirm the key role of intestinal dysbiosis and interaction of the intestinal microflora with the host in the development of neurodegeneration. What is more, over time, the pathological permeability of the intestinal mucosa and blood-brain barrier begins to increase and a vicious circle is formed that irreversibly destroys neurons. It is likely that the convergence of the inflammatory response from the gut along with aging and poor diet in the elderly contributes to the pathogenesis of Alzheimer's disease.

It is a promising idea for prevention or therapeutic intervention. Modulation of the gut microbiota through a personalized diet or beneficial microflora intervention like probiotics or prebiotics, changing microbiological partners and their products, including amyloid protein, can become a new treatment for Alzheimer's disease.

Link: https://doi.org/10.18632/aging.102930

Researchers here provide evidence for natural killer cells to act to reduce inflammation in the brain. This is of interest because chronic inflammation in brain tissue, neuroinflammation, is a prominent feature of neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. If a natural mechanism that suppresses inflammation can be harnessed, it might be possible to slow or reverse neurodegenerative conditions, given that inflammation appears to play such a significant role in their progression. That said, recent work on cellular senescence in the supporting cells of brain suggests that selectively eliminating those senescent cells, and thus their inflammatory signaling, via senolytic therapies might be a more direct and near term approach than further attempts at the manipulation of mechanisms involved in the resolution of inflammation.

Natural killer (NK) cells provide the first line of defense against invasion or a virus and are equipped with activating receptors that can sense cellular stress and identify cells that have been altered due to infection. A new study highlights that NK cells act not only as efficient scavengers that attack an intruder but may be critical for regulating and restraining inflammation of brain tissue and protein clumping - hallmarks of Parkinson's and other neurodegenerative disorders. The report also found that NK cell depletion in a mouse model significantly exaggerated the disease condition. This led to the discovery that, without NK cells, the nervous system was left vulnerable to attack.

"We believe that NK cells exert protection by their ability to reduce inflammation in the brain and clear proteins that misfold and create toxic clumps. In their absence, proteins were left unchecked, and we saw a substantial decrease in viral resistant cells, confirming that NK cells are a major source of signaling proteins that boost the immune system response."

Researchers are quick to caution that the Parkinson's work was done in animal models, but are optimistic about future immunotherapy discoveries. Recent human trials that tested immunotherapies against an aggressive form of brain cancer called glioblastoma, indicating that NK cells contribute to elimination of tumor cells and release messages in support of defense of the immune system. Parkinson's is no longer considered a brain-specific disease, and researchers increasingly recognize a functional connection between the immune system and central nervous system. Researchers found that, in conditions of chronic inflammation such as Parkinson's, the blood-brain barrier becomes disrupted, allowing immune cells to channel into the brain. "Understanding how the periphery signals for NKs to patrol for infectious agents, even in the absence of disease, could lead to breakthrough treatments for Parkinson's disease."

Link: https://news.uga.edu/natural-killer-cells-halt-parkinsons-progression/

Turn.bio is an early venture in the new field of in vivo cellular reprogramming, though it is unclear as to whether the partial reprogramming approach they are taking will eventually be used directly in patients, versus in cell cultures prior to transplantation for cell therapy. The publicity materials here cover some of the work undertaken by one of the scientific founders of Turn.bio in recent years, including the transplantation of partially reprogrammed muscle cells into old mice to restore muscle function.

Cells can be reprogrammed into pluripotent stem cells via expression of a small number of genes - the Yamanaka factors. When applied to old cells, this process has been shown to produce numerous beneficial effects along the way. In cells from old tissues it resets many of the epigenetic changes characteristic of aging, and restores mitochondrial function, for example. So while reprogramming most likely cannot meaningfully address issues such as nuclear DNA damage or accumulated molecular waste that cannot be effectively broken down, even by young cells, it may prove to be a useful basis for therapies to treat aging.

This is all a fairly straightforward proposition when applied to cells outside the body and intended for transplantation. When considering in vivo use, however, the challenge lies in reprogramming to a sufficient degree to produce these benefits, versus reprogramming too much, to the point at which tissue is disrupted and cancer arises. The Turn.bio approach is a partial application of reprogramming, to find the point at which cells are shocked into restoring more youthful function, but not so far as to otherwise change their cell type and function. This is a fine balancing act, likely different for different tissues in the body, and still in a comparatively early stage of development.

Old human cells rejuvenated with stem cell technology

Researchers make induced pluripotent stem cells from adult cells, such as those that compose skin, by repeatedly exposing them over a period of about two weeks to a panel of proteins important to early embryonic development. They do so by introducing daily, short-lived RNA messages into the adult cells. The RNA messages encode the instructions for making the Yamanaka proteins. Over time, these proteins rewind the cells' fate - pushing them backward along the developmental timeline until they resemble the young, embryonic-like pluripotent cells from which they originated.

During this process the cells not only shed any memories of their previous identities, but they revert to a younger state. They accomplish this transformation by wiping their DNA clean of the molecular tags that not only differentiate, say, a skin cell from a heart muscle cell, but of other tags that accumulate as a cell ages. Recently researchers have begun to wonder whether exposing the adult cells to Yamanaka proteins for days rather than weeks could trigger this youthful reversion without inducing full-on pluripotency. In fact, researchers found in 2016 that briefly expressing the four Yamanaka factors in mice with a form of premature aging extended the animals' life span by about 20%. But it wasn't clear whether this approach would work in humans.

wondered whether old human cells would respond in a similar fashion, and whether the response would be limited to just a few cell types or generalizable for many tissues. They devised a way to use genetic material called messenger RNA to temporarily express six reprogramming factors - the four Yamanaka factors plus two additional proteins - in human skin and blood vessel cells. Messenger RNA rapidly degrades in cells, allowing the researchers to tightly control the duration of the signal. The researchers then compared the gene-expression patterns of treated cells and control cells, both obtained from elderly adults, with those of untreated cells from younger people. They found that cells from elderly people exhibited signs of aging reversal after just four days of exposure to the reprogramming factors. Whereas untreated elderly cells expressed higher levels of genes associated with known aging pathways, treated elderly cells more closely resembled younger cells in their patterns of gene expression.

When the researchers transplanted old mouse muscle stem cells that had been treated back into elderly mice, the animals regained the muscle strength of younger mice, they found. Finally, the researchers isolated cells from the cartilage of people with and without osteoarthritis. They found that the temporary exposure of the osteoarthritic cells to the reprogramming factors reduced the secretion of inflammatory molecules and improved the cells' ability to divide and function. The researchers are now optimizing the panel of reprogramming proteins needed to rejuvenate human cells and are exploring the possibility of treating cells or tissues without removing them from the body.

Macrophage cells are derived from circulating monocytes, and, among many other tasks, are responsible for clearing out lipid deposits from blood vessel walls. The conventional view on the age-related nature of atherosclerosis, the build up of fatty deposits that narrow and weaken blood vessels, is that macrophages are vulnerable to oxidized lipids, particularly oxidized cholesterols such as 7-ketocholesterol. These oxidized lipids are far more prevalent in older people, a consequence of the cellular damage of aging. Macrophages in old tissues are overwhelmed by oxidized lipids and become inflammatory, dysfunctional foam cells, and then die, adding their debris to a growing atherosclerotic plaque.

Researchers here argue that the well known decline in mitochondrial function found in all tissues also affects the behavior of monocytes and macrophages in significant ways. Thus loss of mitochondrial function may make a meaningful contribution to the development of atherosclerosis, and methods of restoring mitochondrial function may help to slow the onset of the condition by making macrophages more resilient to the aged environment. As ever, determining the relative size of different contributing mechanisms is a challenging process. The only practical way forward is to put a halt to each different mechanism in isolation, and then observe the results.

Age-related changes at the cellular level include the dysregulation of metabolic and signaling pathways. Analyses of blood leukocytes have revealed a set of alterations that collectively lower their ability to fight infections and resolve inflammation later in life. We studied the transcriptomic, epigenetic, and metabolomic profiles of monocytes extracted from younger adults and individuals over the age of 65 years to map major age-dependent changes in their cellular physiology.

We found that the monocytes from older persons displayed a decrease in the expression of ribosomal and mitochondrial protein genes and exhibited hypomethylation at the HLA class I locus. Additionally, we found elevated gene expression associated with cell motility, including the CX3CR1 and ARID5B genes, which have been associated with the development of atherosclerosis.

Furthermore, the downregulation of two genes, PLA2G4B and ALOX15B, which belong to the arachidonic acid metabolism pathway involved in phosphatidylcholine conversion to anti-inflammatory lipoxins, correlated with increased phosphatidylcholine content in monocytes from older individuals. We found age-related changes in monocyte metabolic fitness, including reduced mitochondrial function and increased glycose consumption without the capacity to upregulate it during increased metabolic needs, and signs of increased oxidative stress and DNA damage.

Link: https://doi.org/10.1111/acel.13127

The consensus position on the role of amyloid-β as a meaningful cause of Alzheimer's disease is under attack. Removal of amyloid-β from human brains has so far failed to reverse or even meaningfully slow the condition, though there are certainly scenarios under which amyloid-β aggregates can be both a contributing cause of Alzheimer's and a poor target for therapy. For example, amyloid-β aggregation might generate sufficient cellular senescence and inflammation in microglia for that pathology to become self-sustaining even when the amyloid-β is later removed. Alternatively, rising levels of amyloid-β might be a side-effect of persistent infections that generate both chronic inflammation and microglial dysfunction sufficient to advance the disease. That second hypothesis, that Alzheimer's is the result of microbial infection, is emerging as the primary challenger to the established amyloid cascade view of the condition.

The infectious theory of Alzheimer's disease (AD) was first proposed some 30 years ago. Since then, the idea has encountered considerable resistance in the research community. Until recently, it had been largely displaced in favor of approaches based on the amyloid hypothesis, the leading theory of Alzheimer's, which identifies plaques of amyloid beta and tangles of tau protein as underlying drivers of the disease. The research landscape for AD, however, may be changing. The repeated failures of amyloid-targeting drugs along with recent discoveries supporting a microbial link to AD have generated fresh interest in this unorthodox approach.

Even before the amyloid hypothesis came under attack as a potential blind alley, alternate theories of the disease had been proposed. Perhaps Alzheimer's is caused not by accumulations of inanimate protein but rather by microorganisms, the way so many infectious diseases are. Researchers have used large data sets in order to explore the prevalence of two common herpesviruses sometimes found in Alzheimer's brain tissue. The study demonstrated that three viral strains appeared in greater abundance in brain samples derived from Alzheimer's patients, compared with normal brains. The viruses also seem to be implicated in the AD-related genetic networks associated with classic Alzheimer's pathology, including cell death, accumulation of amyloid-β and production of neurofibrillary tangles.

The pathogen theory has met with some hostility. Researchers may have insufficient background in microbiology or may inaccurately associate infectious agents solely with acute rather than chronic afflictions, though a number of microbial infections can indeed linger in the body asymptomatically for decades. Perhaps the greatest resistance to the pathogen theory comes from proponents of the amyloid hypothesis, some of whom believe that it will diminish research into amyloid plaques and tau tangles. A microbial link with AD and the amyloid hypothesis may be complementary rather than exclusionary, however. It is still possible that deposition of amyloid instigates a process of neurological decline, followed by opportunistic infections, or that the reverse is the case, with amyloid deposits representing a defense response to infection, trapping invasive microbes in sticky concentrations of amyloid.

Link: https://biodesign.asu.edu/news/viewpoint-could-disease-pathogens-be-dark-matter-behind-alzheimer%E2%80%99s-disease

It has been known for a number of years that cells can ingest mitochondria and put them to work. Researchers here demonstrate that mitochondrial function in heart muscle cells can be improved by co-culturing them with free mitochondria harvested from other cells. The hope is that cells produced for transplantation into heart disease patients can be made more vigorous and effective via this means. Further, it is perhaps the case that mitochondria can be delivered in large numbers into the aging heart in order to improve the function of that tissue in situ.

Mitochondria are the power plants of the cell, each cell containing hundreds of these bacteria-like organelles that are essential to cell function. They produce the chemical energy store molecule adenosine triphosphate, used to power cellular processes. Unfortunately, mitochondrial activity declines with age for reasons that appear related to alterations in the mitochondrial dynamics of fusion and fission, and a related failure of the quality control mechanism of mitophagy, which normally acts to recycle worn and damage mitochondria. Cells become overtaken by large mitochondria as a result of too little fission, resistant to mitophagy.

Efforts to restore mitochondrial function remain at a comparatively early stage. The only practical methodologies presently available, such as NAD+ upregulation and mitochondrially targeted antioxidants, do appear to restore mitophagy and mitochondrial function in older tissues to some degree, but the effect sizes are neither large nor reliable, judging from human trials carried out to date. Better therapies are needed, and one possible approach to this challenge is the periodic delivery of new mitochondria. It remains to be seen how long fresh mitochondria will last before succumbing to the same environmental factors that degraded native mitochondria, but initial results here suggest that the benefit is short-lived, on the order of a few days to a week.

Researchers demonstrate the ability to supercharge cells with mitochondrial transplantation

Researchers have shown that they can give cells a short-term boost of energy through mitochondrial transplantation. Researchers first isolated mitochondria by differential centrifugation, followed by transplantation through coincubation. Once the mitochondria had settled in their new host cells, they performed metabolic flux analysis to measure two key parameters: the oxygen consumption rate and the extracellular acidification rate, which provide important information about cellular metabolism and how well the cells are consuming/producing energy. The analyses were conducted at two, seven, 14 and 28 days.

"Regarding the viability of mitochondrial transplantation in different cell lines, we've done a lot of variations, including work with skeletal muscle cells, T-cells, and cardiomyocytes. We even tested the feasibility of transplanting mitochondria from rat cells to commercially available human cells, in our lab, to see if there's a mechanism that prevents such a procedure; we found that transplanting mitochondria between different species is also possible." Next, the team plans to investigate whether the internalized mitochondria establish signaling with the cell's nucleus and whether they'll be adopted by the host on a long-term basis.

Bioenergetics Consequences of Mitochondrial Transplantation in Cardiomyocytes

We first established the feasibility of autologous, non-autologous, and interspecies mitochondrial transplantation. Then we quantitated the bioenergetics consequences of non-autologous mitochondrial transplantation into cardiomyocytes up to 28 days. Compared with the control, we observed a statistically significant improvement in basal respiration and ATP production 2-day post-transplantation, accompanied by an increase in maximal respiration and spare respiratory capacity, although not statistically significantly. However, these initial improvements were short-lived and the bioenergetics advantages return to the baseline level in subsequent time points.

This study, for the first time, shows that transplantation of non-autologous mitochondria from healthy skeletal muscle cells into normal cardiomyocytes leads to short-term improvement of bioenergetics indicating "supercharged" state. However, over time these improved effects disappear, which suggests transplantation of mitochondria may have a potential application in settings where there is an acute stress.

Over the past twenty years a great deal of work has gone into the investigation of protein deacetylases, such as SIRT1, in the context of aging and longevity. Here, researchers note some of the evidence for the other side of the coin, protein acetyltransferases, to also influence life span in short-lived laboratory species. It seems plausible that interventions based on these mechanisms will also produce negligible effects once attempted in humans: all of these metabolic manipulations appear to scale down in their benefits as species life span increases. Treatments that make nematode worms live twice as long typically have little to no useful outcome in humans. This isn't a part of the field that is likely to produce meaningful treatments for aging, judging by the work taken place to date.

The level of acetylation on a given protein is the result of a balance in the activity of opposing families of enzymes, protein lysine acetyltransferases that attach the acetyl moieties and protein deacetylases that remove the acetyl groups. The idea that protein acetylation plays an important role in the regulation of aging began with the pioneering work on the sirtuin family of NAD+-dependent protein deacetylases. Studies in model organisms such as, flies, worms and mice, showed that genetic or pharmacological modulation of sirtuin activity influenced lifespan. While a role for protein deacetylases in aging is firmly established, the enzymes on the other side of the equation, the protein lysine acetyltransferases, have not received a proportionate share of research into understanding their potential roles in the regulation of aging.

Protein N-ε-lysine acetyltransferases (KATs) are a diverse family of enzymes. While many of these enzymes were originally identified as histone acetyltransferases, it is now clear that most, if not all, have multiple substrates. From a broad perspective, it is not surprising that KATs are likely to play key roles in the aging process. KATs modify proteins involved in many cellular processes including those linked to the hallmarks of aging.

Recent studies have now shown that several KATs are directly linked to the aging process and that genetic and pharmacological manipulation of KATs can influence lifespan. Our understanding of the link between KATs and aging clearly has a long way to go to match our understanding of sirtuins. Important questions that need to be addressed include determining the relevant aging-related cellular processes that each KAT functions in and identifying aging-relevant substrates for each KAT. It will take intensive investigation to decipher the molecular mechanisms underlying the influence of KATs on aging and lifespan.

Link: https://doi.org/10.18632/aging.102949

This open access review paper looks at stress granules in the context of aging. These are transient structures that form within cells, made up of a wide variety of biomolecules. There is a lot of information about stress granules in the literature, but a great deal of it is speculative. This is one of the less well explored areas of cellular biochemistry. Cells form these assemblies of under stressful conditions, and their function may be protective - perhaps a way to stash useful molecules and protect them from an aggressive upregulation of cellular maintenance activities, or perhaps a way to make those useful molecules more available to needed locations in the cell by putting a stockpile in close proximity.

There is evidence for stress granules to become abnormal in the cells of aged tissues, and this may be due to raised levels of misfolded or otherwise broken proteins and other forms of molecular waste. Whether the consequences are significant in comparison to other, better explored mechanisms of aging remains to be determined.

Stress granules (SGs) are membraneless assemblies. They form when cells experience stress conditions, and are thought to influence cellular signaling pathways, and mRNA function, localization, and turn over SGs are dynamic, complex, and variable assemblies, with composition and structure that can vary dramatically under different types of stresses, such as heat shock, oxidative stress, osmotic stress, nutrient starvation, and UV irradiation. SGs have two distinct layers with different components, functions, and dynamics: a stable inner core structure surrounded by a less dense shell layer. The components in the core structure are believed to be less dynamic, while the components in the shell layer are more dynamic.

Severe stress- and aging-related misfolded proteins could specifically accumulate and aggregate within SGs, which could alter SG composition, impair SG dynamics, and, finally, lead to aberrant conversion from a liquid-like to a solid-like state. Under mild stress conditions or normal growth conditions, the cellular chaperone machinery and degradation systems are sufficient to manage the surveillance of such aberrant interactions between RNA-binding proteins (RBPs) and other aggregation-prone proteins. In young cells, multiple cellular defense systems can protect the cells from being affected by damaging changes such as imbalanced cellular proteostasis and proteolysis, inappropriate covalent modifications, and lowered pH levels. In aged cells, however, age-dependent breakdown of such systems may lead to defects in maintaining normal SG assembly, dynamics, disassembly, and clearance. This in turn could lead to the subsequent onset of a barrage of diseases.

Further in-depth investigations will help to reveal the mechanisms underlying the interactions between SGs and aging. First of all, what are the components of SGs formed under chronic stress caused by aging-induced intracellular environmental changes? Dynamic analysis of changes in the properties of SGs and SG components during the aging process could provide vital clues on how aging influences SG formation. Whether these changes exert a synergistic effect that could accelerate aging will be an important question to be answered.

Moreover, it is known that aggregation-prone proteins can be recruited to SGs and that this could result in aberrant or persistent SGs during cellular stress and after the stress subsides. These aberrant SGs might induce a series of effects that can be attributed to reduced stress resistance with age. Such aberrant SGs may also act as seeds to facilitate the formation of irreversible mature protein aggregates in aged cells, further accelerating the decline of the cellular functions of these proteins. Thus, it seems that maintaining a proper SG dynamic might be a potential strategy to delay aging and increase lifespan. Two key questions that remain to be answered are as follows: (a) What kind of proteins are prone to form aggregates during aging? And (b) is aggregation triggered by interactions between aggregation-prone proteins and SG components?

Link: https://doi.org/10.1111/acel.13136

Ronjon Nag is a noted angel investor in the Bay Area, and one of the newer entries to the select community of investors interested in the longevity industry. He brings his own perspective to the table; new points of view are always welcome as the community grows in size, and as more narrowly focused specialists begin to emerge. That said, given the enormous venture funding still in waiting, looking for places to invest, there is always the perverse incentive for fund managers to consider the space of aging and longevity in the broadest sense possible. There is a pressure to invest now, invest soon, find more deals to participate in. This leads one to invest in what might be profitable ventures, but ventures that do nothing to help address aging, and are only engaged in some form of compensation for aging. Eldercare, supportive services, tools to help people who have lost function. I expect many funding institutions to lose their way in this fashion.

These are, of course, interesting times for investors, to say the least: we are amidst something of a hysteria regarding all things viral, and also in the opening weeks of a bear market that is long overdue and thus likely to be more unpleasant than usual. If one had to invest somewhere under the present circumstances, there are certainly worse options than a preclinical biotech company working on new therapies, however. Such a company is essentially immune to the vagaries of the broader market at any time other than when it has to raise funds. For much of its life, it keeps to itself, carries out its research, and engages with regulators rather than customers. The opening weeks of a crash are a great time to provide the funds for a biotech company to carry out a year or two of work. By the time the company is ready for the next step and the next round of fundraising, the market will have turned around.

Talking Longevity investment and risk with Ronjon Nag

We understand that you're looking at longevity as a dedicated investment category - what are the main differences you see to regular healthcare investing?

We look at longevity in the widest sense. In addition to biotech there could be investments in areas such as lifelong learning, fintech for the aged, and work opportunity platforms for the aging workforce. Cutting across these themes, we like to see a computational element and the application of artificial intelligence and data-mining within these companies. I tend to agree that this is a new space that will develop as a pure play over the next few years - both in terms of understanding the landscape and having enough quality targets to invest in. I look at artificial intelligence, longevity, and healthcare and cover all those segments to have enough vehicles to invest in.

You've helped over 50 companies secure funding - what are you looking for in new start-ups?

Firstly, we typically like to invest very early, at the seed or pre-stage stage, often being among the first to write checks for new startups; so early stage is one dimension. We like to help shape the company at the earliest stages. Secondly, we like to invest in difficult technologies, which usually means they are unique and have very little competition. As such patents, although helpful, are not what we particularly look for - we would rather we see the potential for a business-technology 'moat' combination irrespective of any patent position. Thirdly, the product, technology and team must have strong science and/or computational components. An ideal team would be recent doctoral graduates combined with seasoned industrialists who get along with each other.

We cover longevity in a wide context - i.e. beyond rejuvenation technologies, what areas do you categorise as longevity?

Yes, we have the same view; there will be many societal impacts and there will be many different products other than biotech. These could be robots (helpers or companions), self-driving vehicles, workplace marketplaces, or telecommunications enhancers to allow for at home-work interactivity. For example when developing products for the disabled the products then will be used by a wider audience. Previously texting as a communication method allowed mobile phone makers to enable communication with deaf people, yet it turned out that this functionality was liked and widely used by everybody.

Are there any longevity companies that you've invested in that would be of interest to our readers?

There is a macro trend of increasing computation capability, both in terms of computer processing speed and increased availability of medical data. Healx.ai is trying to speed up the production of drugs by a factor of 20, and also reduce the cost of drug discovery by a factor of 20. The initial targets are diseases, but one would expect that hundreds of treatments could be created at a fraction of a cost of traditional methodologies. Another one is Exonate which has a treatment for macular degeneration - the normal treatment requires an injection into the eye which is not very pleasant for the patient or the doctor. Exonate is working on an eye drop and has a strategic arrangement with Janssen.

Greater physical activity correlates well with lower mortality in later life. Given the way that human data is collected, and the way in which epidemiological studies are carried out, it is hard to determine causation, however. Is it that exercise is protective, or is it that more robust people both live longer and exercise more often? Fortunately the equivalent animal studies on exercise are unambiguous, and show that exercise does in fact act to improve long-term health and reduce premature mortality. Here, researchers expand on the existing evidence by focusing on trends in physical exercise in later life, and how those trends correlate with mortality. They find the expected outcome, in that a reduction in exercise over time is worse than the alternatives.

Lifelong physical activity (PA) promotes a wide range of health benefits and has long been recognized as an important protective factor for chronic diseases. These beneficial effects consistently translate into lower mortality rates in both men and women. The salutary effects of PA might extend to late life, as it is known to delay the onset of disability and to increase lifespan. Furthermore, PA might be negatively associated with other adverse outcomes such as hospitalization, thereby reducing health care expenditure. Remarkably, at advanced ages, PA levels might surpass other cardiovascular or sociodemographic risk factors that are classically associated with adverse outcomes in younger cohorts.

A common methodological limitation in exploring the association between PA and adverse outcomes in older populations is the use of a single time-point assessment of PA (primarily the baseline PA levels) as the exposure variable, which does not account for the dynamic nature of PA behaviours. It is plausible that prospective trajectories (patterns) of PA levels along time in late life may influence adverse outcomes distinctly as compared with cross-sectional estimates, a hypothesis that remains untested to our knowledge. The main aim of this study is to investigate the existence of different PA trajectories within the Toledo Study of Healthy Aging (TSHA) sample, a Spanish longitudinal population-based study, and to evaluate their associations with adverse outcomes (mortality, disability onset and worsening, and hospitalization).

We found four PA-decreasing and one PA-increasing trajectories: high PA-consistent (n = 566), moderate PA-mildly decreasing (n = 392), low PA-increasing (n = 237), moderate PA-consistent (n = 191), and low PA-decreasing (n = 293). Belonging to the high PA-consistent trajectory group was associated with reduced risks of mortality as compared with the low PA-decreasing group (hazard ratio (HR) 1.68) and hospitalization compared with the low PA-increasing and low PA-decreasing trajectory groups (HR 1.24 and HR 1.25, respectively) and with lower rates of incident (odds ratio (OR) 3.14) and worsening disability (OR 2.16) in relation to the low PA-decreasing trajectory group and at follow-up. Increasing PA during late life (low PA-increasing group) was associated with lower incident disability rates (OR 0.38) compared with the low PA-decreasing group, despite similar baseline PA.

Link: https://doi.org/10.1002/jcsm.12566

Researchers here discuss the evidence for intermittent use of rapamycin, an mTOR inhibitor that has undesirable side-effects, to be a path forward to producing benefits in older people. We should probably weigh the animal evidence for this class of therapy against the recent failure of a phase III trial for a related form of mTOR inhibition designed to bypass the side-effects of rapamycin. The beneficial effect sizes in humans may be too small to be worth the cost and time of development at the end of the day, and this is somewhat characteristic of interventions, such as mTOR inhibition, that upregulate cellular stress responses such as autophagy. The effect sizes scale down with increased species life span. This is perhaps best illustrated by calorie restriction, an intervention that also acts through increased autophagy. While the practice of calorie restriction can extend life span by up to 40% in short-lived mice, it adds a few years at best in long-lived humans.

Rapamycin is arguably the best-studied pharmaceutical intervention for reliable lifespan and healthspan extension in a wide array of model organisms. These consistent results are encouraging for those eager to develop interventions for prolonging human lifespan or healthspan. Until recently publications of rapamycin treatment in animal models focused on near lifelong treatment, a scenario that is unrealistic to apply to improving the human condition. However, this is beginning to change. A few groups have endeavored to address this by administering rapamycin to mammalian model organisms beginning at mid- to late-life. Results so far have been encouraging - even when delivered late in life, rapamycin can improve both health- and lifespan in mice.

To bring the field even closer to a limited duration regimen that continues to benefit the organism in late life, some groups have published that both intermittent or transient rapamycin treatment can improve lifespan or organ function. Our own work has demonstrated that 8 weeks of rapamycin delivered late in life in mice can confer an improvement in diastolic heart function. This effect persisted for a further 8 weeks post-treatment, even after the metabolic changes due to acute treatment reverted back to pre-treatment levels. That rapamycin could be useful for larger mammals was given credence through a study of dog cardiac outcomes: 10 weeks of rapamycin administered to middle-aged companion dogs was sufficient to improve measures of both systolic and diastolic cardiac function.

A critical goal of any pharmaceutical treatment is to minimize off-target effects. Rapamycin's use in the clinic has been extensive, and side-effects have been reported, though they generally resolve when the drug is removed. Efforts to reduce these off-target responses in humans have ranged from co-treatment with another drug, reducing the dose of rapamycin, and changing the dosing schedule to a more intermittent or transient one. Altering the delivery of rapamycin from continuous to intermittent may help in animal models as well; it was found that the positive effects of an intermittent rapamycin treatment can be separated from its side effects. At 2mg/kg per day, every five days, beginning at 20 months of age in mice, rapamycin could increase medial and maximal lifespan without detrimental effects on glucose homeostasis. This was also in the absence of metabolic effects seen in models using higher/longer-term doses of rapamycin. Intermittent treatment may, therefore, help to balance the minimization of off-target effects with the desired continual boost to health-span.

Link: https://doi.org/10.18632/aging.102947

Cells become senescent in response to a variety of circumstances. The vast majority are cases of replicative senescence, somatic cells reaching the Hayflick limit. Cell damage and toxic environments also produce senescence, and senescent cells are also created as a part of the wound healing process. A senescent cell ceases replication and begins to secrete inflammatory and pro-growth signals, altering the nearby extracellular matrix and behavior of surrounding cells - even encouraging them to become senescent as well.

Near all senescent cells last a short time only, as they self-destruct or are removed by the immune system. When the presence of senescent cells is transient, their signals are a useful part of the processes of regeneration following injury. Cellular senescence also serves to lower the risk of cancer, ensuring that cells with significant DNA damage (or that might gain significant DNA damage due to a locally genotoxic environment) are prevented from replication. Senescent cells linger with age, however. In older tissues they last longer and are created in greater numbers, and their signals become very harmful when present for the long term. In this way, cellular senescence is an important cause of aging.

While compelling evidence has existed for decades for the accumulation of senescent cells to be a contributing cause of aging, this area of study has only comparatively recently found acceptance and significant funding. A decade ago near all work on senescent cells took place in the context of cancer, carried out by researchers who didn't think that senescence was all that relevant to aging at all. Cancers generate senescent cells by their very nature, and there is a complex relationship between cellular senescence and cancerous tissues. Senescence is an initially protective mechanism when the number of cells (cancerous and senescent) is small, locking down replication and summoning immune cells. Given established cancer tissue, or the burden of senescent cells in old tissues, then the inflammatory, pro-growth signaling of senescent cells instead encourages cancer growth and spread. Some cancers, particularly leukemias, even appear to aggressively generate more senescent cells in order to accelerate their growth.

Bone Marrow Senescence and the Microenvironment of Hematological Malignancies

Bone marrow (BM) disorders, including myeloproliferative neoplasm (MPN), myelodysplastic syndrome (MDS), leukemia, and multiple myeloma are largely diseases of the elderly and as our population ages their incidence will likely continue to increase and with it, disease associated mortality. Acute myeloid leukemia (AML), alone accounted for 85,000 deaths globally in 2016 and multiple myeloma caused 98,000 deaths. Hematopoietic malignancies including AML multiple myeloma, MPNs, and MDS are highly dependent on the bone marrow microenvironment for survival.

The BM is the primary hematopoietic organ in adults. It comprises of blood vessels, nerve tissue, and a heterogeneous population of cells that are either directly involved in the generation of blood cells or support the hematopoietic function of the tissue. Together, all the components of the BM tightly regulate normal hematopoiesis to ensure adequate production of mature blood cells. In blood cancers, however, this process is disrupted resulting in cytopenias and immunosuppression. In AML, this is thought to be instigated by leukemic cells directly blocking differentiation of normal hematopoietic stem cells (HSC), as well as the manipulation of other BM-derived cells (including macrophages, endothelial cells, fibroblasts, and adipocytes).

Cellular senescence is the irreversible arrest of cell proliferation. It is associated with the secretion of numerous pro-inflammatory cytokines, chemokines, proteases, and growth factors, known as the senescence-associated secretory phenotype (SASP). It occurs as a response to cellular damage and is thought to have evolved to both suppress development of cancer and to promote tissue repair and wound healing. In the short term the SASP plays an important role in recruiting immune cells to sites of cellular damage in order to promote tissue repair, limit tissue fibrosis, and clear senescent cells. However, it appears that this process becomes less effective with age and senescent cells gradually accumulate. Overall the senescent response becomes maladaptive and there is now increasing evidence that it contributes to a number of age-related phenotypes and pathologies. When it persists over time the SASP has paradoxically been shown to disrupt a number of cellular and tissue functions to create a pro-tumoral and chemotherapy-resistant environment.

Age related changes within the BM microenvironment contribute to the development of hematological malignancies. These changes can also affect disease progression and response to treatment, and this may contribute, for example, to poorer outcomes observed in older patients with AML, which are not sufficiently explained by the differences in adverse prognostic features. AML cells were shown to induce a senescent phenotype in BM stromal cells (BMSCs) resulting in the secretion of a SASP which supports the survival and proliferation of leukemic blasts. In vivo experiments, using the p16-3MR model of senescence, showed that leukemic blast derived superoxide induces p16INK4A driven senescence in BMSCs and that deletion of these senescent BMSCs slows tumor progression and prolongs animal survival.

mesenchymal stem cells which creates an environment that supports myeloma cells growth, although the exact relationship between the myeloma cells and the senescent mesenchymal stem cells remains to be explored further. However, as with a number of solid tumors it is becoming increasingly clear that a senescent microenvironment favors survival of malignant cells in the bone marrow. It remains yet to be determined whether an existing senescent environment, as is observed with increasing age, drives the development of these malignancies or whether in fact the expansion of clonal cell populations within the bone marrow microenvironment drives the senescent process, accelerates aging and impairs immunosurveillance and clearance of both senescent cells and pre-malignant cells. It is also possible that these two processes together create the senescent BM microenvironment that is observed both with increasing age and in BM malignancies.

However, as there is increasing evidence that senescence in the bone marrow microenvironment forms a fundamental part of the malignant phenotype, this raises the question whether targeting the "benign" senescent cells in the BM microenvironment could disrupt the supportive nature of the tumor microenvironment and as a result impair tumor survival.

The review paper here provides an interesting perspective on the interaction between mitochondria and lysosomes, looking at the mechanics of their membrane contact sites in the context of mitochondrial quality control and its age-related decline. Every cell plays host to hundreds of mitochondria, bacteria-like organelles responsible for generating adenosine triphosphate molecules to power cellular processes. Mitochondrial function declines throughout the body with age, and this appears to be largely a problem of failing quality control. The quality control processes of mitophagy identify worn and damaged mitochondria, ensuring that they are transported to a lysosome to be dismantled by enzymes. As mitophagy falters, cells become host to ever more malfunctioning or poorly functioning mitochondria, and this has profound negative effects on tissue function, particularly in energy-hungry organs such as the brain and heart.

Mitochondrial dysfunction has attracted considerable interest as a target for geroprotective interventions. Indeed, mitochondria play varied roles in a multitude of biological processes, including integration of cell death signaling and preservation of cell stemness. Albeit long considered to be standalone organelles, a great deal of evidence indicates that mitochondria interact physically and functionally with other cellular compartments via membrane contact sites and tethering molecules. In particular, mitochondria establish connections with the endosomal compartment and lysosomes. These interactions support cytosolic shuttle systems of ions and metabolites across organelles, and participate to the regulation of cellular housekeeping processes.

The mitochondrial-lysosomal axis is a major actor in mitochondrial quality control (MQC), a hierarchical network of pathways that ensure organellar homeostasis through the coordination of mitochondrial proteostasis, dynamics, biogenesis, and autophagy. While continuous cycles of fusion and fission preserve mitochondrial shape and dilute damage along the network mitochondrial hyper-fission segregates damaged or unnecessary organelles from the network. Severely damaged mitochondria are subsequently disposed via a selective form of autophagy referred to as mitophagy. Cleared mitochondria are eventually replenished via biogenesis to maintain an adequate mitochondrial pool within the cell.

Dysregulation of mitophagy and disruption of the mitochondrial-lysosomal axis coupled with abnormal EV secretion have been implicated as mechanisms in the aging process and related disease conditions. More specifically, the garbage theory of aging poses that damaged mitochondria, protein aggregates, and lipofuscin accumulate as a result of inefficient cellular quality control. The progressive accrual of intracellular "waste" further depresses cell recycling processes, thereby impinging on cell homeostasis and tissue integrity.

Functional connections between lysosomes and mitochondria have been described. Indeed, defects in either of the two organelles induce impairments in the other, indicating the existence of a mitochondrial-lysosomal axis. The genetic ablation of mitochondrial transcription factor A (TFAM), responsible for mitochondrial DNA replication, transcription, and maintenance, increases the number of lysosomes in T cells. However, lysosomal activity is impaired when deficient mitochondrial respiration and disruption of endolysosomal trafficking occur, suggesting a link between primary mitochondrial dysfunction and lysosomal storage disorders. Moreover, the restoration of lysosomal pH by lysosome-targeted nanoparticles reinstates mitophagy in pancreatic cells exposed to high concentrations of free fatty acids. These findings indicate that, at least under lipotoxic conditions, mitochondrial dysfunction develops downstream of lysosomal alkalization and that recovery of lysosomal acidity restores MQC.

Mitochondrial dysfunction, arising from failure of mitochondrial fidelity pathways, is a major mechanism driving aging and the development of age-related diseases. In this context, MQC processes may represent ideal targets for geroprotective interventions. Notably, many of the proteins involved in MQC pathways have been localized at inter-organelle interface. Such contact sites may therefore participate to some of the processes responsible for cell dyshomeostasis triggered by mitochondrial dysfunction. Hence, a deeper characterization of the structures ensuring inter - organelle crosstalk is crucial for a comprehensive assessment of mitochondrial dysfunction during aging. This knowledge, in turn, is necessary to unveil strategic pathways that may be targeted for geroprotective interventions.

Link: https://doi.org/10.3390/cells9030598

Researchers here show that miR-21 and miR-217 are important in the way in which senescent cells can encourage nearby cells to also become senescent. These microRNAs are carried between cells via extracellular vesicles, small membrane-bound packages of molecules that might constitute the bulk of cell signaling activity. The research community has of late given a lot more attention to vesicle based signaling in a number of contexts. It remains to be seen whether or not discoveries in this part of the field will lead, in the near future, to effective points of intervention in the matter of senescent cell accumulation with age or in cancer.

Cellular senescence is considered as a hallmark of ageing and a major risk factor for the development of the most common age-related diseases (ARDs). Senescent cells (SCs) are characterised by a significantly reduced replicative potential and by the acquisition of a pro-inflammatory senescence-associated secretory phenotype (SASP), which involves the paracrine induction of a senescent state in younger cells through a "bystander effect". Since this effect fuels inflammaging - the systemic, low-grade, chronic inflammation that accompanies human ageing - it appears to be a critical step in SC accumulation during organismal ageing.

Senescence modulation by microRNAs (miRNAs) is a major senescence-related epigenetic mechanism. This has been suggested, among other findings, by the identification of discrete miRNA signatures associated with senescence in different cell types and by the fact that living cells can actively release extracellular vesicles (EVs), which contain different species and amounts of non-coding RNAs. EVs seem to reflect the molecular characteristics of their cells of origin and to modulate the phenotype of recipient cells both in a paracrine and in a systemic manner.

This study was devised to unravel the relative contribution of EVs released from senescent ECs in spreading pro-senescence signals to proliferating cells via their miRNA cargo. Based on the evidence that the in vitro replicative senescence of ECs substantially mimics the progressive age-related impairment of endothelial function described in vivo, we set out to identify the miRNAs that are differentially expressed in senescent and non-senescent human umbilical vein endothelial cells (HUVECs) and their EVs.

MicroRNA profiling of small EVs (sEVs) and large EVs demonstrated that senescent cells release a significantly greater sEV number than control cells. sEVs were enriched in miR-21-5p and miR-217, which target DNMT1 and SIRT1. Treatment of control cells with senescent cell sEVs induced a miR-21/miR-217-related impairment of DNMT1-SIRT1 expression, the reduction of proliferation markers, the acquisition of a senescent phenotype, and a partial demethylation of the locus encoding for miR-21. MicroRNA profiling of sEVs from plasma of healthy subjects aged 40-100 years showed an inverse U-shaped age-related trend for miR-21-5p, consistent with senescence-associated biomarker profiles. Our findings suggest that miR-21-5p/miR-217 carried by senescent cell sEVs spread pro-senescence signals, affecting DNA methylation and cell replication.

Link: https://doi.org/10.1080/20013078.2020.1725285

In that part of the research community focused on the role of cellular senescence in aging, the consensus is that the markers presently used to identify senescent cells are placeholders waiting for a better approach. They are not sufficiently universal. Senescent cells might be different enough in different tissues to require tissue specific approaches to assess their presence to a usefully exact degree.

This point is illustrated by the results of a recent survey of p16 and p21 in humans by tissue type and age. That neither p16 nor p21 expressing cells increased in number with age in lung tissue strongly suggests that senescent cells in lungs are meaningfully different from those elsewhere in the body, at least in this aspect of their biochemistry. Humans should certainly be expected to have an increase in senescent cells in the lungs, as in all tissues, with advancing age. The same argument applies to the apparent absence of p16 and p21 expressing cells in muscle.

Why do we want reasonably accurate measures of senescent cell burdens by tissue? Because this will be needed as a part of the development and validation of senolytic therapies capable of selectively destroying senescent cells. Early programs are getting by with the existing markers, but as the myriad age-related diseases that can be turned back via senolytic treatments are explored in greater depth, better assays will be needed. In clinical practice, people will want an assessment of senescence burden, not just symptoms, as a way to decide when to apply treatments prior to the development of significant dysfunction. These are important considerations, and the present markers are just not up to the task.

Survey of senescent cell markers with age in human tissues

Cellular senescence, triggered by sublethal damage, is characterized by indefinite growth arrest, altered gene expression patterns, and a senescence-associated secretory phenotype. While the accumulation of senescent cells during aging decreases tissue function and promotes many age-related diseases, at present there is no universal marker to detect senescent cells in tissues.

Cyclin-dependent kinase inhibitors 2A (p16/CDKN2A) and 1A (p21/CDKN1A) can identify senescent cells, but few studies have examined the numbers of cells expressing these markers in different organs as a function of age. Here, we investigated systematically p16- and p21-positive cells in tissue arrays designed to include normal organs from persons across a broad spectrum of ages.

Increased numbers of p21-positive and p16-positive cells with donor age were found in skin (epidermis), pancreas, and kidney, while p16-expressing cells increased in brain cortex, liver, spleen, and intestine (colon), and p21-expressing cells increased in skin (dermis). The numbers of cells expressing p16 or p21 in lung did not change with age, and muscle did not appear to have p21- or p16-positive cells. In summary, different organs display different levels of the senescent proteins p16 and p21 as a function of age across the human life span.

Researchers here make the point that calorie restriction studies in animals are also introducing a strong component of time restricted feeding, as animals tend to be fed once a day. Studies of intermittent fasting without calorie reduction have shown that this can produce a similar set of metabolic responses to a reduced calorie intake. Intermittent fasting and calorie restriction have been shown to improve health and extend healthy life spans via two overlapping sets of mechanisms, as assessed by various omics approaches. Thus the details of the approach to feeding animals any given fixed amount of calories (delivery of food per a day versus the same caloric intake split between several deliveries spaced over the day) will likely bias the results of any study.

Rodents are the most popular model to study caloric restriction (CR) in mammals. There are several ways to implement CR to rodents. One common method of food delivery is when a reduced amount of food (about 60%-80% of daily intake) is provided as a single meal once per day, usually, at the same time of the day. This type of CR induces strong food anticipation, and animals usually consume the food in a short (1-3 hr) period of time following a 21-hr period of fasting. Thus, CR is a self-imposed time-restricted (TR) feeding.

TR feeding, when an unlimited amount of food is provided for a limited time frame, significantly improves metabolic health of mice on high-fat (HF) or high-sugar diets, and this improvement in metabolism has been linked with restored or increased circadian rhythms in gene expression and signaling. Importantly, most TR studies were conducted in context of high-fat diet, obesity, or circadian rhythm disruption. Much less is known about the effect of TR on regular chow in healthy mammals.

Mealtime feeding (MTF) is another example of TR diet: 100% of daily food is provided once per day as a single meal; for unknown reasons, animals consume all food during a limited time frame in about 8-12 hr. Importantly, MTF increases longevity in mice independent of the caloric intake, suggesting that manipulation with the feeding schedule might have beneficial effects on longevity; however, the effect on lifespan is not as strong as the effect of CR. All three interventions: CR, TR, and MTF are periodic feeding/fasting diets. It was hypothesized that fasting can improve metabolism. Indeed, fasting mimicking diets such as ketogenic diet and intermittent fasting have positive effects on metabolism and, in some cases, on longevity which supports the potential importance of periodic fasting in health.

In order to understand the relative contribution of reduced food intake and periodic fasting to the health benefits of CR, we compared physiological and metabolic changes induced by CR and TR (without reduced food intake) in mice. CR significantly reduced blood glucose and insulin around the clock, improved glucose tolerance, and increased insulin sensitivity. TR reduced blood insulin and increased insulin sensitivity, but in contrast to CR, TR did not improve glucose homeostasis. Liver expression of circadian clock genes was affected by both diets while the mRNA expression of glucose metabolism genes was significantly induced by CR, and not by TR, which is in agreement with the minor effect of TR on glucose metabolism. Thus, periodic fasting contributes to some metabolic benefits of CR, but TR is metabolically different from CR. This difference might contribute to differential effects of CR and TR on longevity.

Link: https://doi.org/10.1111/acel.13138

Cardiopoietic stem cells are used in a form of autologous mesenchymal stem cell therapy. Cells are extracted from patient bone marrow, expanded in culture, and provoked into adopting a cardiac lineage, such that they produce daughter cardiac muscle cells. Human trials have shown benefits in heart attack patients, but, as for all such therapies, it is a question as the degree to which signaling versus integration produces these benefits. Is greater regeneration the result of signaling that changes native cell behavior, followed by the death of near all of the transplanted cells, versus integration of a fraction of those transplanted cells and consequent creation of daughter cells to repair and maintain tissue?

Examining the proteomic differences before and after treatment, as is carried out in mice in this paper, doesn't actually say all that much about which mechanism is dominant. Nonetheless, it is an interesting approach to evaluating exactly what is going on under the hood, and one that should probably be more widely applied during the development of stem cell therapies.

Cardiopoiesis leverages natural developmental cues to impart lineage engagement for enhanced cardioreparative outcome. Applied to adult stem cells, recombinant growth factor-induced cardiopoiesis disrupts latent plasticity to prime cardiovasculogenesis while maintaining a proliferative state. Supported by preclinical studies, cardiopoietic stem (CP) cell-based therapy for heart failure is undergoing clinical evaluation. While global readouts of functional and structural safety and efficacy have been the focus of exploration to date, delineation of the molecular impact of CP cells upon the recipient heart has yet to be charted.

Accordingly, proteomic profiling was here applied to characterize cardiac molecular maladaptation to ischemic cardiomyopathy, and delineate the response of diseased hearts to CP cell treatment. To this end, cells were lineage guided from human bone marrow-derived mesenchymal stem cells (MSCs), consistent with clinical trial cell sourcing. Therapeutic application of human CP cells in a xenograft model of ischemic cardiomyopathy enabled whole ventricle evaluation unachievable from clinical trial participants. This integrative approach resolved widespread proteome remodeling within the infarcted tissue, and captured a non-random reversal of these disease-perturbed derangements following stem cell treatment.

Mass spectrometry resolved and quantified 3987 proteins constituting the cardiac proteome. Infarction altered 450 proteins, reduced to 283 by stem cell treatment. Notably, cell therapy non-stochastically reversed a majority of infarction-provoked changes, remediating 85% of disease-affected protein clusters. Pathway and network analysis decoded functional reorganization, distinguished by prioritization of vasculogenesis, cardiac development, organ regeneration, and differentiation. Subproteome restoration nullified adverse ischemic effects, validated by echo-/electro-cardiographic documentation of improved cardiac chamber size, reduced QT prolongation and augmented ejection fraction post-cell therapy. Collectively, cardiopoietic stem cell intervention transitioned infarcted hearts from a cardiomyopathic trajectory towards pre-disease.

Link: https://doi.org/10.1038/s41536-020-0091-6

Every cell contains hundreds of mitochondria, cell structures that evolved long ago from symbiotic bacteria. They carry remnants of the original bacterial DNA, and continually fuse and divide like bacteria. Mitochondria participate in many core cellular processes, but arguably their most important function is to produce the chemical energy store molecule adenosine triphosphate (ATP), needed to keep the cell running. This is an energetic process, and produces free radicals such as reactive oxygen species (ROS) as a side-effect. ROS damage cellular machinery, provoking the activity of repair mechanisms. This damage is actually used as a signal, such as when it triggers the beneficial response to exercise: mitochondria work harder, moderately more ROS is generated, and muscle cells have evolved to repair and build tissue in response.

Too much ROS, too great a level of oxidative damage, is harmful, however. It overwhelms repair and maintenance mechanisms, giving rise to the state of oxidative stress. This is characteristic of old tissues and age-related disease, and early theories of aging focused strongly on oxidative damage as a primary mechanism by which aging leads to age-related disease. The picture is more nuanced than this, however, and where oxidative stress falls in the chain of first causes and downstream consequences continues to be debated.

In today's open access research, scientists point out certain aspects of mitochondrial biochemistry that might contribute to the exceptional longevity of bats and naked mole-rats in comparison to mice and other similarly sized mammals. The mitochondria of naked mole-rats and bats preserve a mild depolarization response that minimizes ROS production, and they do this more effectively than mice. It is possible to argue that in the case of bats the metabolic demands of flight, and in the case of naked mole-rats oxygen-poor underground environments, have led to mitochondria that are more resilient to processes of aging. It is still hard to pick out what is cause and what is consequence, however, and it is hard to assess affect size in terms of the degree to which exceptional species longevity results from one mechanism versus another mechanism. Mitochondria are only one of a number of mechanisms of longevity studied in naked mole-rats, and relative contributions are debated.

Newly confirmed biochemical mechanism in mouse, bat and naked mole rat cells is a key component of the anti-ageing program

Naked mole rats, an east African rodent of a size comparable to moles or mice, show a strongly delayed process of ageing and live up to 30 years. Scientists now confirmed a mechanism in mouse, bat and naked mole rat cells - a "mild depolarization" of the inner mitochondrial membrane - that is linked to ageing: Mild depolarization regulates the creation of mitochondrial reactive oxygen species (mROS) in cells and is therefore a mechanism of the anti-ageing program. In mice, this mechanism falls apart at the age of 1 year, while in naked mole rats this does not occur until ages of up to 20 years.

Mitochondrial reactive oxygen species (mROS) such as hydrogen peroxide are by-products of cell respiration and, in higher doses, associated with various diseases and ageing processes. There are different mechanisms at the inner and outer mitochondrial membranes that regulate the mROS production. Key function of cell respiration is energy production in the form of ATP (adenosine triphosphate) through coupling of mitochondrial respiratory chain complexes with ATP synthase. Different mitochondrial intermembrane space enzymes (hexokinases I + II and creatine kinase) have now been confirmed to slightly lower the membrane potential of the inner mitochondrial membrane ("mild depolarization"). This means that the differences in the electric load between the inner and the outer space of the mitochondria are lowered and the energy production through ATP synthesis is reduced to some extent. At the same time this leads to the cessation of mROS production.

The research team was able to show that both biochemical mechanisms do not operate in the same intensity and efficiency in different species and tissues and at different ages: The researchers examined the hexokinases I + II and creatine kinase mechanisms in various tissues (lung, kidney, brain, skeletal muscles, heart, and others) in mice (Mus musculus), naked mole rats (Heterocephalus glaber), and Seba's short-tailed bats (Carollia perspicillata). They found interesting differences: Mild depolarization significantly starts decreasing after 1 year of age in mice with negligible levels after 24 months in skeletal muscles, diaphragm, heart, brain, and spleen. In lung and kidney tissue, mild depolarization decreases to a lesser extent with ageing. "The crumbling of the anti-ageing program in the cells starts after only a third of the average life span in mice, while the naked mole rats and Seba's short-tailed bats maintain mild depolarisation and hence the suppression of mROS production up to high ages. This contributes to the extraordinary longevity of these species."

Mild depolarization of the inner mitochondrial membrane is a crucial component of an anti-aging program

The mitochondria of various tissues from mice, naked mole rats (NMRs), and bats possess two mechanistically similar systems to prevent the generation of mitochondrial reactive oxygen species (mROS): hexokinases I and II and creatine kinase bound to mitochondrial membranes. Both systems operate in a manner such that one of the kinase substrates (mitochondrial ATP) is electrophoretically transported by the ATP/ADP antiporter to the catalytic site of bound hexokinase or bound creatine kinase without ATP dilution in the cytosol.

One of the kinase reaction products, ADP, is transported back to the mitochondrial matrix via the antiporter, again through an electrophoretic process without cytosol dilution. The system in question continuously supports H+-ATP synthase with ADP until glucose or creatine is available. Under these conditions, the membrane potential, ∆ψ, is maintained at a lower than maximal level (i.e., mild depolarization of mitochondria). This ∆ψ decrease is sufficient to completely inhibit mROS generation.

In 2.5-y-old mice, mild depolarization disappears in the skeletal muscles, diaphragm, heart, spleen, and brain and partially in the lung and kidney. This age-dependent decrease in the levels of bound kinases is not observed in NMRs and bats for many years. As a result, ROS-mediated protein damage, which is substantial during the aging of short-lived mice, is stabilized at low levels during the aging of long-lived NMRs and bats. It is suggested that this mitochondrial mild depolarization is a crucial component of the mitochondrial anti-aging system.

The results of this epidemiological study don't include any great surprises, but do present a convenient summary of the effect sizes of some of the commonly assessed lifestyle and environmental factors known to influence long-term health and thus life expectancy. This means smoking, level of exercise, whether or not one is overweight, undergoing sustained psychological stress, and so forth. The largest missing factor is likely degree of exposure to persistent pathogens such as cytomegalovirus, but this data is challenging to obtain across large populations, and thus isn't present in epidemiological databases.

All of that said, the advent of practical, working rejuvenation therapies (such as senolytic treatments) will render these present variations in life expectancy largely irrelevant. In a world in which technological progress is ongoing, the pace of progress towards various means of treating aging as a medical condition will become the largest determinant of future life expectancy.

Most people want to live a long and healthy life. Choices affecting the prospects of achieving this goal are continually made by individuals themselves and by health professionals. Which amenable determinants of health and longevity should be emphasised in specific individual situations? It is well known from observational epidemiological studies that risk factors describing the sociodemographic background, lifestyles, dietary factors, life satisfaction (LS), and metabolic health predict mortality. For example, vigorous physical activity has been found to decrease the risk of death by 22% compared with no physical activity. Smoking has been found to increase the hazard by 83% and life dissatisfaction by 49%.

Comparisons between different risk factors and their impact on survival could be carried out using expected age of death (EAD) that is easier to interpret than commonly presented hazard ratios. Evidence-based decisions on how to improve the length of life, tailored to specific individual contexts, require reliable information on the EAD for different levels of these risk factors. In this study, we analyse total mortality using a model with a large number of risk factors that have previously been found to be predictors of longevity. The study assessed a otal of 38,549 participants aged 25-74 years at baseline of the National FINRISK Study between 1987 and 2007. The Primary outcome measures were register-based comprehensive mortality data from 1987 to 2014 with an average follow-up time of 16 years and 4310 deaths.

The largest influence on the EAD appeared to be a current smoker versus a never smoker as the EAD for a 30-year-old man decreased from 86.8 years, which corresponds to the reference values of the risk factors, to 82.6 years, and additionally, smoking 20 cigarettes per day decreased EAD further to 80.2 years while keeping all other risk factors at the same values. Diabetes decreased EAD almost as much to 80.3 years. Whole or full milk consumers had EAD of 84.5 years compared with 87.9 years of those consuming skimmed milk. Physically inactive men had EAD of 85.0 years whereas those with high activity had EAD of 87.4 years. Men, who found their life almost unbearable due to stress, had EAD of 84.0 years. For older men and for women the differences were similar but smaller.

BMI values below 22 and above 33, non-HDL cholesterol values below 3.6 and above 6.5, diastolic blood pressure above 85 and systolic blood pressure values below 110 and above 135 appeared to reduce the EAD when compared with the lowest risk values, but these optimal values are based on the other risk factors being at their optimal values. In practice, for example, overweight and obesity can increase blood pressure compared with normal weight, which can increase mortality.

Link: http://dx.doi.org/10.1136/bmjopen-2019-033741

It is no big secret that maintaining a healthier lifestyle will extend the time spent free from age-related disease and generally improve the experience of later life. In this day and age, and now that the very harmful practice of smoking is waning somewhat, the practice of maintaining better health largely means resisting the siren call of excess calories and consequent excess weight. The presence of visceral fat tissue in excessive amounts accelerates the aging process. Staying slim over the course of life thus pays off down the line. If you instead choose to damage yourself in this way, the inevitable result is an earlier onset of chronic ill health, greater medical expense, and a shorter life expectancy.

The longer you lead a healthy lifestyle during midlife, the less likely you are to develop certain diseases in later life. The more time a person doesn't smoke, eats healthy, exercises regularly, maintains healthy blood pressure, blood sugar and cholesterol levels, and maintains a normal weight, the less likely they are to develop diseases such as hypertension, diabetes, chronic kidney disease, cardiovascular disease, or to die during early adulthood.

While unhealthy lifestyle behaviors are associated with higher risks for certain diseases and death, the association of the duration in which people maintain a healthy lifestyle with the risk of disease and death had not yet been studied.

Using data from the Framingham Heart Study, researchers observed participants for approximately 16 years and assessed the development of disease or death. They found that for each five-year period that participants had intermediate or ideal cardiovascular health, they were 33 percent less likely to develop hypertension, approximately 25 percent less likely to develop diabetes, chronic kidney disease, and cardiovascular disease, and 14 percent less likely to die compared to individuals in poor cardiovascular health.

Link: https://www.eurekalert.org/pub_releases/2020-03/buso-hlr030920.php

Every cell contains hundreds of mitochondria, bacteria-like organelles that work to provide the cell with adenosine triphosphate (ATP), a chemical energy store molecule to power cellular biochemistry. With age, mitochondrial function falters throughout the body. This may be largely a consequence of failing mitophagy, a form of the cellular maintenance process of autophagy that is responsible for destroying worn and damaged mitochondria. In tissues with high energy demands, such as the heart, this loss of function is a sizable contributing factor in the development of age-related disease.

At present the research and development communities are still in the comparatively early stages in the production of ways to address this problem. Both upregulation of NAD+ in mitochondria and delivery of mitochondrially targeted antioxidants appear to somewhat reverse the loss of mitophagy, and thus improve mitochondrial function, but the outcomes in human trials and animal models are not reliably positive at this point in time. The effect size of these treatments is likely not large enough. A range of better approaches lie ahead, such as periodic delivery of large numbers of whole mitochondria harvested from cell cultures, but even these classes of treatment do not address the root causes of mitochondrial decline.

Researchers have identified a number of proteins important to mitophagy wherein expression changes with age, but connecting these changes to the underlying damage that causes aging is yet to be accomplished. Repairing forms of molecular damage known to cause aging and observing the results in mitochondria is probably a faster strategy than trying to work backwards from the present understanding of disrupted regulation of mitophagy. This sort of approach could be carried out today for clearance of senescent cells, and some forms of stem cell transplantation, but most forms of cell and tissue damage thought to cause aging still require potential therapies to be further developed.

The Aging Heart: Mitophagy at the Center of Rejuvenation

Aging is associated with structural and functional changes in the heart and is a major risk factor in developing cardiovascular disease. Many recent studies have focused on increasing our understanding of the basis of aging at the cellular and molecular levels in various tissues, including the heart. It is known that there is an age-related decline in cellular quality control pathways such as autophagy and mitophagy, which leads to accumulation of potentially harmful cellular components in cardiac myocytes.

A growing body of data support the anti-aging effects of enhanced autophagy. Many studies have demonstrated that enhancing autophagy by limiting caloric intake, genetic manipulation, or pharmacological treatments increases lifespan in various organisms. For instance, transgenic mice with systemic overexpression of Atg5 have enhanced autophagic activity in tissues which leads to health benefits such as reduced weight gain with age and extended life spans compared to wild type mice.

The cardioprotective effects of enhanced autophagy during the aging process were recently confirmed, who developed a Becn1 knock-in mouse model with constitutively increased basal autophagy due to a disruption in the Bcl-2 binding to Becn1. They found that health and life spans are significantly increased in the knock-in mice. Moreover, aged Becn1 knock-in mice have reduced cardiac hypertrophy and interstitial fibrosis compared to aged-matched wild type mice, confirming that preserving autophagy in the heart delays or even prevents cardiac aging.

In summary, declines in autophagy and mitophagy in tissues clearly play a role in the aging process and contribute to development of age-related diseases. The main questions that remain unanswered include: why are autophagy and mitophagy suppressed with age and can these pathways be restored in the aged heart? Relatively little is still known about the molecular mechanism underlying the decrease in autophagy and mitophagy and whether there are tissue specific differences. Although manipulation of autophagy and mitophagy pathways are protective in pre-clinical models, the level of activity must be carefully monitored as excessive autophagy can lead to excessive degradation of key cellular components. Increased knowledge into how these pathways are regulated as well as altered with age will allow for more specific manipulation. Further understanding will also provide important insights into how future therapies can protect the heart against age-specific functional decline.

Excess fat tissue raises blood pressure. Chronically raised blood pressure, hypertension, in turn causes tissue damage to organs throughout the body. This is one of the ways in which being overweight accelerates the progression of degenerative aging and onset of age-related diseases. Researchers here report on the investigation of one of the biochemical mechanisms by which obesity can raise blood pressure; having identified it, interfering in the mechanism is the next logical step.

With obesity comes greater risk of cardiovascular disease, high blood pressure (hypertension) and stroke, among other health problems. Small arteries in our body control blood pressure. Scientists have suspected that hypertension in obesity is related to problems in endothelial cells that line these small arteries. The reasons for this, however, have been unclear - until now.

Researchers found that a protein on the membranes surrounding endothelial cells allows calcium to enter the cells and maintains normal blood pressure. Obesity, it turns out, affects this protein, called TRPV4, within tiny subsections of the cell membrane. The researchers call these faulty subsections "pathological microdomains." Obesity, the researchers found, increases the levels of peroxynitrite-making enzymes in the microdomains containing TRPV4. Peroxynitrite silences TRPV4 and lowers calcium entry into the cells. Without the proper amount of calcium, blood pressure goes up. Targeting peroxynitrite or the enzymes that make it could be an effective way to treat and prevent high blood pressure in obesity, without the side effects that would come with trying to target TRPV4 itself.

"Historically, researchers have studied larger blood vessels that don't control blood pressure. Because of our unique techniques, we are able to study the microdomains in very small arteries that control the blood pressure. Under healthy conditions, TRPV4 at these tiny microdomains helps maintain normal blood pressure. We, for the first time, show the sequence of events that lead to a harmful microenvironment for calcium entry through TRPV4. I think the concept of pathological microdomains is going to be very important not just for obesity-related studies but for studies of other cardiovascular disorders as well."

Link: https://newsroom.uvahealth.com/2020/03/09/uva-discovers-why-obesity-causes-high-blood-pressure/

Amyloid-β is one of the few proteins in the human body capable of misfolding in a way that encourages aggregation, causing the misfolded version to spread and form harmful deposits in tissues. This process is best known in the context of Alzheimer's disease, where an active debate continues over whether it is actually an important part of the condition or a side-effect of other important mechanisms. Amyloid-β aggregation also occurs in the cardiovascular system, however. There is some evidence for the presence of amyloid-β in brain and vasculature to be in a state of dynamic equilibrium, but equally the disease processes that arise in these two locations might still be largely independent of one another.

Aging-related cellular and molecular processes including low-grade inflammation are major players in the pathogenesis of cardiovascular disease (CVD) and Alzheimer's disease (AD). Epidemiological studies report an independent interaction between the development of dementia and the incidence of CVD in several populations, suggesting the presence of overlapping molecular mechanisms. Accumulating experimental and clinical evidence suggests that amyloid-beta (Aβ) peptides may function as a link among aging, CVD, and AD.

Experimental evidence indicates that Aβ peptides may be actively involved in downstream pathways leading to plaque rupture, thrombosis, and subsequent clinical manifestations of the acute coronary syndrome (ACS). Αβ1-40 stimulates platelet activation and adhesion in humans and mice and induces release of matrix metalloproteinases by human monocytes to increase plaque vulnerability. Although patients with coronary artery disease (CAD) are more likely to develop AD-like neuropathological lesions than those without CAD, whether atherogenesis occurs in parallel or independently from brain parenchyma amyloid load in humans is unknown.

A pathophysiological role of Aβ1-40 across the continuum of cardiovascular disease is suggested through its independent association with a broad spectrum of vascular and cardiac involvement from early functional vascular alterations and subclinical atherosclerosis to overt symptomatic CAD, ACS, and heart failure. This is robustly supported by experimental evidence that amyloid precursor protein (APP) and Aβ1-40 are critically involved in vascular inflammation, vascular and cardiac aging, and atherothrombosis. Thus, Aβ1-40 fulfills several criteria for consideration as a new biomarker for risk stratification in cardiovascular disease.

Most importantly, multiple lines of evidence clearly indicate that manipulating APP/Aβ turnover and aggregation or blocking its inflammatory reactions is feasible, potentially improving our understanding and means to simultaneously protect the brain, heart, and vessels during physiological or premature aging.

Link: https://doi.org/10.1016/j.jacc.2019.12.033

Multiple proteins can be assembled from the blueprint of a any given gene, depending on which of the intron sequences (usually removed) and exon sequences (usually retained) within the overall gene sequence are included in the final protein. Splicing is the part of the gene expression process that determines this outcome, and regulation of splicing is one of the many aspects of cellular biochemistry that becomes disarrayed with age. It is an open question as to how important this is versus other processes in aging, as well as how far downstream from the root causes of aging splicing dysfunction might be, but splicing changes might be relevant in the pace of creation of senescent cells, to pick one example.

Naked mole-rats are exceptionally long-lived for their size as rodents, and by comparing their biochemistry to that of similarly sized mice, researchers have found a range of mechanisms that might contribute to this longevity. Naked mole-rats exhibit very good DNA repair; naked mole-rat senescent cells do not secrete damaging and inflammatory signals; cancer suppression mechanisms are very effective; and so forth. Researchers here add stability of splicing regulation to the list. Naked mole-rats do not exhibit the age-related changes in splicing factor expression observed in other mammals, and splicing thus remains stable throughout most of life.

Negligible senescence in naked mole rats may be a consequence of well-maintained splicing regulation

Naked mole-rats (NMRs) have amongst the longest lifespans relative to body size of any known, non-volant mammalian species. They also display an enhanced stress resistance phenotype, negligible senescence and very rarely are they burdened with chronic age-related diseases. Alternative splicing (AS) dysregulation is emerging as a potential driver of senescence and ageing. We hypothesised that the expression of splicing factors, important regulators of patterns of AS, may differ in NMRs when compared to other species with relatively shorter lifespans.

We designed assays specific to NMR splicing regulatory factors and also to a panel of pre-selected brain-expressed genes known to demonstrate senescence-related alterations in AS in other species, and measured age-related changes in the transcript expression levels of these using embryonic and neonatal developmental stages through to extreme old age in NMR brain samples. We also compared splicing factor expression in both young mouse and NMR spleen and brain samples. Both NMR tissues showed approximately double the expression levels observed in tissues from similarly sized mice. Furthermore, contrary to observations in other species, following a brief period of labile expression in early life stages, adult NMR splicing factors and patterns of AS for functionally relevant brain genes remained remarkably stable for at least two decades.

These findings are consistent with a model whereby the conservation of splicing regulation and stable patterns of AS may contribute to better molecular stress responses and the avoidance of senescence in NMRs, contributing to their exceptional lifespan and prolonged healthspan.

Researchers here report on preliminary evidence that antibodies binding to TREM2 can enhance the ability of the immune cells known as microglia to clear out debris and metabolic waste in brain, particularly the amyloid-β plaques thought to contribute to the progression of the condition. Given the unremitting record of failure to date for amyloid-β clearance approaches to produce material benefits in patients, it is something of a question as to whether more and better clearance is what is needed right now. From a reductionist point of view, amyloid-β aggregates should indeed be removed, as their presence is a material difference between old and young brains. That doesn't mean that amyloid-β is necessarily the primary driver of the disease state, however. Perhaps its contribution will only become clear once the other pathologies of Alzheimer's disease have been addressed: neuroinflammation, tau aggregates, and vascular dysfunction.

Researchers have identified a specific antibody that binds to the brain's immune cells, termed "microglia". This stimulates their activity in such a way that they live longer, divide more quickly and detect aberrant substances more easily. In mice with disease symptoms resembling those of Alzheimer's, studies revealed that deposits of proteins (called "plaques") were recognized and degraded more quickly. The notorious plaques are among the hallmarks of Alzheimer's disease, and are suspected to cause neuronal damage.

The research focuses on TREM2, a so-called receptor on the cell surface to which other molecules can attach. TREM2 can occur in different versions from person to person - some of these altered versions drastically increase the risk of developing Alzheimer's in old age. In previous studies, researchers found that these special variants put the microglia into an irreversible dormant state, which prevents the immune cells from functioning properly to recognize, absorb and break down plaques and dead cells. "Conversely, we suspect that activation of the microglia could help to eliminate plaques and thus combat Alzheimer's. TREM2 seems to play an important role in this process. The receptor apparently helps to switch the microglia from dormant to active mode."

This is precisely the approach the team are pursuing. The antibody identified, which is now generated using biotechnological methods, binds to TREM2, thereby triggering processes that enhance microglia activity. However, the researchers cautioned that further studies are required prior to progressing this approach to clinical trials: "We have shown that immune cells can be stimulated to break down amyloid deposits more effectively. This demonstrates that our approach can work in principle. However, there is still a long way to go before it can be tested in humans and additional data is necessary to validate this approach."

Link: https://www.dzne.de/en/news/press-releases/press/immune-cells-against-alzheimers/

Intermittent fasting strategies such as alternate day fasting are known to be beneficial to health in humans and both health and longevity in animal models. A portion of this outcome likely stems from some degree of reduction in overall calorie intake, but animal studies in which calorie intake is consistent between control and intermittent fasting groups demonstrate that benefits still arise even when calories are not reduced. Lengthy enough periods of hunger likely trigger the same cellular maintenance mechanisms as play a role in the metabolic response to calorie restriction when practiced without fasting. The biochemistry of this response is enormously complex, however. Near everything in cellular metabolism is affected, often in different ways in different organs, and thus even after decades of research, the scientific community is still finding new mechanisms to explore.

In experiments with mice, researchers identified how every-other-day fasting affected proteins in the liver, showing unexpected impact on fatty acid metabolism and the surprising role played by a master regulator protein that controls many biological pathways in the liver and other organs. In particular, the researchers found that the HNF4α protein, which regulates a large number of liver genes, plays a previously unknown role during intermittent fasting.

"For the first time we showed that HNF4α is inhibited during intermittent fasting. This has downstream consequences, such as lowering the abundance of blood proteins in inflammation or affecting bile synthesis. This helps explain some of the previously known facts about intermittent fasting." The researchers also found that every-other-day-fasting - where no food was consumed on alternate days - changed the metabolism of fatty acids in the liver, knowledge that could be applied to improvements in glucose tolerance and the regulation of diabetes.

"What's really exciting is that this new knowledge about the role of HNF4α means it could be possible to mimic some of the effects of intermittent fasting through the development of liver-specific HNF4α regulators."

Link: https://www.eurekalert.org/pub_releases/2020-03/uos-hif030420.php

While it is still a small field in comparison to much of biotechnology and medicine, research into slowing and reversing the aging process has achieved legitimacy and growth in the past decade. This newfound capacity for progress results from a great deal of work by patient advocates, visionary researchers, and other allies to overcome public disinterest and a hostile leadership in the field of gerontology.

Sadly, most participants in the now energized research and development communities are pursuing varieties of a poor strategy, often called geroscience. They have taken the wrong realization regarding the plasticity of aging, and are working on lines of development that are unlikely to produce large effects on human life span. This work descends from the earliest and best supported modern investigations of aging interventions. It involves the search for longevity-related genes, near all of which manipulate stress response systems (such as autophagy) that can slow aging in short lived animals. Calorie restriction research is one of the major areas of work, but there are numerous others that touch on ways to make animal metabolism more optimal for longevity than is the case in the wild.

Unfortunately, we already have all the evidence we need to show that these systems of cellular maintenance - activated by stresses such as starvation, cold, heat, and toxins - have comparatively small effects on longevity in long-lived species. Calorie restriction extends life by up to 40% in mice, but it certainly doesn't add more than a few years in humans. Further, the practice of calorie restriction cannot greatly reverse the state of aging once it has occurred. It is very much a case of better than nothing, but not a road to dramatic rejuvenation or lengthening of life.

Some people see the uptake of interest in aging research and the building of a longevity industry, and feel justified in saying that an inflection point has passed. That is the case in today's open access paper, quoted below. The real inflection point still lies ahead, however, in the adoption of a truly viable strategy to produce human rejuvenation - a strategy based on damage repair that is quite different from the majority of present work on aging. This inflection point will occur when significant portions of the research community buckle down to work on repairing the molecular damage that causes aging, rather than tinkering with metabolism to slightly slow down the accumulation of that damage. This transition has yet to happen. Until it does, progress will be marginal.

From discoveries in ageing research to therapeutics for healthy ageing

The rapid increase in our understanding of the molecular mechanisms that underlie ageing has created new opportunities to intervene in the ageing process. Two notable findings have emerged from these early studies. First, the number of genes that can extend lifespan is much larger than expected, which suggests a much higher level of plasticity in the ageing process than expected. Second, genes that control ageing - which define cellular pathways such as the TOR and insulin signalling pathways - are remarkably conserved in yeast, worms, fruit flies and humans. The conservation of these pathways across wide evolutionary distances and the fact that targeting these pathways in model organisms increases both lifespan and healthspan has brought to the fore the idea of interventions in humans.

Rapidly ageing societies across the world are seeing an increasing healthcare burden attributable to both morbidity and cost of age-related diseases, such as heart disease, stroke, cancer, neurodegeneration, osteoarthritis, and macular degeneration. However, current medical care is highly segmented as well as organ- and disease-based, and ignores the fact that age and the ageing process are the strongest risk factor for each of these diseases. According to the concept of geroscience, targeting conserved ageing pathways is anticipated to protect against multiple diseases and represents a different approach to tackling the rapidly growing burden of diseases worldwide.

The concept of geroscience predicts that conserved ageing pathways are part of the pathophysiology of many age-related conditions and diseases. For example, multimorbidity is seen as the multisystem expression of an advanced stage of ageing rather than a coincidence of unrelated diseases. Targeting conserved ageing pathways should, therefore, prevent or ameliorate multiple clinical problems. This hypothesis remains to be tested in clinical trials, but is supported by several lines of evidence. A wide range of animal models of specific diseases can be affected by manipulating a single ageing mechanism (such as NAD+) or senescent cells in the laboratory. Rates of individual age-related diseases and of multimorbidity increase nonlinearly with age, and the rate of acquiring new chronic diseases may be higher in people who have an existing chronic disease.

We are now entering an exciting era for research on ageing. This era holds unprecedented promise for increasing human healthspan: preventing, delaying or - in some cases - reversing many of the pathologies of ageing based on new scientific discoveries. Whether this era promises to increase the maximum life span of humans remains an open question. What is clear is that, 30 years after the fundamental discoveries that link unique genes to ageing, a solid foundation has been built and clinical trials that directly target the ageing process are being initiated. Although considerable difficulties can be expected as we translate this research to humans, the potential rewards in terms of healthy ageing far outweigh the risks.

Researchers here report on their investigations of one small part of the complex biochemistry of chronic inflammation and oxidative stress that is observed in aging blood vessels. This sort of work is carried out in search of novel target proteins and mechanisms that might be influenced in order to treat age-related vascular conditions, those that arise from the downstream consequences of chronic inflammation in older individuals. It would be a better approach to address the causes of age-related chronic inflammation rather than adjust its mechanisms or immediate consequences, but this remains a less popular strategy in the research community. The quest for complete understanding of any given disease process tends to shed light on proximate causes and immediate consequences, and thus that is where most new therapeutic development is focused.

CEACAM1 contributes to angiogenesis by induction of vascular sprouting, but has not been associated with the vascular aging process until recently. It has been known for a long time that the pro-inflammatory cytokine TNF-α is upregulated within the wall of aging vasculature and contributes to endothelial dysfunction that in turn predicts cardiovascular events. Since we showed previously that CEACAM1 is critically involved in TNF-α-mediated endothelial barrier breakdown via adherens junction disassembly, we wondered whether CEACAM1 might also contribute to vascular aging.

As a first hint, we observed re-expression of CEACAM1 in the murine and human vasculature with progressive age. This upregulation of vascular CEACAM1 expression is of great importance since we demonstrated that the presence of CEACAM1 is necessary for age-associated vascular upregulation of TNF-α using a murine CEACAM1 knockout model. Reversely, TNF-α induced the expression of CEACAM1 in cultured endothelial cells, indicating the establishment of a vicious cycle within aging vessels.

A hallmark of vascular aging is the increased deposition of collagen fibers within the media of larger vessels. Intriguingly, we found that only in the presence of CEACAM1 vascular aging in mice was accompanied by vascular fibrosis presumably due to enhanced TGF-β/TGF-βR1 signaling whereas genetic deletion of CEACAM1 completely prevented aortic collagen accumulation. Age-related CEACAM1-dependent vascular collagen accumulation might increase arterial stiffness, which is known to augment cardiac afterload permanently resulting in concentric ventricular hypertrophy and cardiomyopathy.

Finally, we found that CEACAM1 contributes to the age-related increase in oxidative stress within the vasculature which promotes endothelial barrier impairment. It is well-known that oxidative stress is also critically involved in processes that promote angiopathies like atherosclerosis. Although there are some hints pointing to a role of CEACAM1 in atherosclerosis the exact contribution of CEACAM1 in these processes is yet to be defined.

In summary, we identified CEACAM1 as an important player in the process of vascular aging. Identification of mechanisms of vascular aging in detail that are regulated by endothelial and vascular presence of CEACAM1 might therefore open up new therapeutic strategies to slow-down the vascular aging process thereby reducing the risk of life-threatening cardiovascular events.

Link: https://doi.org/10.18632/aging.102868

Researchers here report on the application of a novel form of cellular reprogramming that might be more useful than the present standard approach when it comes to generating patient-matched cells and tissues for regenerative medicine. They demonstrate this via the creation of vascular progenitor cells that might be used to treat some forms of retinal degeneration in which blood vessels in that tissue have atrophied.

Scientists began their experiments with a fibroblast - a connective tissue cell - taken from a person with type 1 diabetes. Reprogrammed fibroblasts function as stem cells, with the potential to give rise to all tissues in the body, including blood vessels. The team reprogrammed the fibroblast stem cells to revert to a state that is even more primitive than that of conventional human induced pluripotent stem cells - more like the state of embryonic cells about six days after fertilization. This is when cells are the most "naive," or more capable of developing into any specialized type of cell with a much higher efficiency than conventional human induced pluripotent stem cells.

Researchers used a cocktail mixture of two drugs that other scientists previously used to reprogram stem cells: GSK3β inhibitor CHIR99021, which blocks carbohydrate storage in cells, and MEK inhibitor PD0325901, an experimental anti-cancer drug that can block cancer cell growth. The team had also looked at the potential of a third drug, a PARP inhibitor - a popular anticancer drug used to treat a variety of cancers including those of the ovaries and breast. The team calls the cocktail 3i, named for the three inhibitors.

The research team tracked the reprogrammed stem cells' molecular profile, including measures of proteins such as NANOG, NR5A2, DPPA3 and E-cadherin that guide cell differentiation. That profile appeared similar to that found in so-called naive epiblast cells, the primitive cells that make up an approximately six day-old human embryo. The scientists also found that the stem cells reprogrammed with the 3i cocktail did not have abnormal changes in factors that can alter core DNA, called epigenetics, that typically plague other lab-made versions of naive stem cells. "Interestingly, the 3i cocktail appeared to erase disease-associated epigenetics in the donor cells, and brought them back to a healthy, pristine non-diabetic stem cell state."

Finally, the research team injected cells called vascular progenitors, which were made from the naive stem cells and are capable of making new blood vessels, into the eyes of mice bred to have a form of diabetic retinopathy that results from blood vessels closing off in the retina. They found that the naive vascular progenitors migrated into the retina's innermost tissue layer that encircles the eye, with higher efficiencies than have been reported with vascular cells made from conventional stem cell approaches. The naive vascular cells took root there, and most survived in the retina for the duration of the four-week study.

Link: https://www.hopkinsmedicine.org/news/newsroom/news-releases/primitive-stem-cells-shown-to-regenerate-blood-vessels-in-the-eye

Today I'll point out a couple of short interviews on the topic of investment in the longevity industry. This industry is young and still quite small, taking its present shape over the last five years or so. There are a little more than a hundred companies in the industry, a dozen venture funds that make significant numbers of investments, and - as of yet - no approved drugs emerged from phase III trials. Most programs are still at a preclinical stage of development. From the archly conservative perspective of Big Pharma and the largest established biotech venture funds, this whole endeavor remains an experiment in its early stages.

Nonetheless, more nimble and visionary concerns are definitely taking notice, and a considerable influx of entrepreneurs and capital is underway. It is now quite challenging to keep track of the new companies arriving on the scene from quarter to quarter. Numerous new venture funds are setting up shop, focused specifically on the longevity industry, and existing funds are shifting their strategies to include this space. Most of the new investors I've spoken to, while fundraising for Repair Biotechnologies, or at conferences, are motivated as much by the prospect of improving the human condition, of bringing aging under medical control, as by returns on investment.

Longevity venture capital - a case in point

Having now gone through several significant investment rounds, Eric Marcotulli, CEO of Elysium Health is ideally positioned to comment on whether investors are yet seeing longevity as an investment category and we raised this with him during our recent interview. Considering the question, he recalls seeing Elizabeth Blackburn, a Nobel Prize winner for her work on telomeres, giving a talk on investment. "She said if she walked up and down Sand Hill Road saying that her work had discovered the cure for a very specific form of cancer, she would probably be able to get a blank check from anybody she sat with. But if she walked in there and said her work could potentially impact on cancer, Alzheimer's, diabetes, cardiovascular disease, and so on, she'd be laughed out of the room. And I think that was a really great encapsulation of the State of the Union, not just on her research, but on aging itself."

Marcotulli concurs that much of the investment community is perhaps "a little behind" when it comes to longevity and anti-aging, although he points out that there are those who are ahead of the field. "Those types of people will have the ultimate advantage. But, broadly speaking, the investor community thinks the way that consumers and patients think. At the end of the day they want to see the data so that, in less than 10 seconds, they can see what the benefit of the products your company are developing will be. We've made great progress in identifying and agreeing the key pillars of aging. However, what we still haven't shown conclusively, especially in humans, is are there discrete impacts, how interconnected they are, are certain ones more or greater contributors than others? And, more importantly, how do we measure the impact of changes to the different processes, what does it take to actually change those processes, and what does changing those processes mean?"

The Longevity landscape and investment potential

What is the so-called "Longevity Hype"?

Back in 2013, Silicon Valley tech giant Google promised the world that it will solve the problem of death. We have entered a new decade now, however, in my opinion, the progress in actual, practical life extension of humans is not far away from where it was back in 2013. There is lots of positive hype on the subject: many people ranging from the general public to scientists, entrepreneurs and investors are confident that we are on the brink of creating actual human life extension techniques which will soon translate into real-world, accessible applications. These claims need to be validated and a set of guidelines used to help separate hype from reality around this hypothesis in a concrete, logical and tangible way.

There has been tangible progress in the field, though?

Absolutely. A number of longevity-focused scientists have achieved a rather significant progress over the last decade with respect to stalling the aging process and in some cases even rejuvenation (restoring a young phenotype) in certain model organisms such as yeast, worms, flies and mice, including Maria Blasco and colleagues managing to extend the lifespan of mice by 24% by breeding a set of chimeric mice using embryonic stem cells with telomeres twice as long as usual.

So what happens next?

Undoubtedly, gaining a sufficient understanding of the nature of human aging and longevity as well as the necessary scope of technologies required for practical human life extension to the point of achieving Longevity Escape Velocity (the point where more years are added onto the human lifespan than are taken away due to aging) would require substantial resources. However, compared with the amount of funds being spent even on general aging research, not to mention the myriad of diseases that have their root causes in aging, we are not talking about unthinkable numbers. We estimate that $100bn per year over 10 years would be more than enough to get a real understanding and implementation of the technologies necessary for practical extension of healthy human longevity, which is vastly less than the amounts currently being spent on cancer research or on FinTech, for example.

Age-related upregulation of CD38 is quite closely related to the decline of NAD+ levels in mitochondria. That in turn causes some fraction of the age-related loss of mitochondrial quality control and mitochondrial function. As mitochondria are the power plants of the cell, providing chemical energy store molecules (adenosine triphosphate, ATP) to power cellular operations, this causes a broad range of issues in tissues throughout the body. Mitochondrial decline is particularly influential in the aging of the brain, given the high energy demands of that organ.

Due to the lack of effective treatment to at least slow down the neurodegenerative process, neurodegenerative diseases (NDDs) are still an unmet medical need. Most high-profile clinical trials for NDDs led to inefficacious results, suggesting that novel approaches to treat these pathologies are needed. Targeting NDDs through the prism of aging is one of such approach. Indeed, the primary risk factor associated with NDDs, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, or Huntington's disease is aging. Consequently, it is tempting to study age-related dysfunctions that could favor or be instrumental in the neurodegenerative process.

Reduced nicotinamide adenine dinucleotide (NAD) levels might be one of these age-related dysfunctions influencing neurodegeneration. Indeed, NAD levels were found to decrease as a consequence of aging, including in the human brain and cerebrospinal fluid (CSF), while NAD was found to be a potent neuroprotective and anti-inflammatory molecule. The reason as to why NAD levels are reduced as a consequence of aging remained elusive until the discovery in 2016 that expression of CD38, the main enzyme responsible for NAD degradation, increased as a consequence of aging, thus explaining age-related NAD decline. Moreover, CD38 deletion was found to repress neurodegeneration and neuroinflammation in experimental models of NDDs.

However, CD38 biology is complex and not restricted to its NAD-degrading ability. The aims of this review are to summarize the physiological role played by CD38 in the brain, present the arguments indicating the involvement of CD38 in neurodegeneration and neuroinflammation, and to discuss these observations in light of CD38 complex biology.

Link: https://doi.org/10.3390/cells9020471

It was discovered comparatively recently that laboratory species exhibit a plasticity of life span that is passed across generations. This can be epigenetic, in which the offspring of calorie restricted parents exhibit some of the same metabolic responses to calorie restriction even in its absence. In the other direction, stresses in a parent during pregnancy can lead to an acceleration of degenerative aging in offspring.

Researchers here demonstrate this second class of mechanism across four generations of rats, in which the final generation exhibits measurably accelerated manifestations of aging. One question that springs to mind is the degree to which differences in the gestational environment can explain the natural variation in aging within a mammalian species. How much of the distribution of life spans is this, versus later environmental circumstances such as exposure to pathogens?

Experiences in early life may lay the foundation for age-related non-communicable disease (NCD) suseptibility. The developmental origins of health and disease (DOHaD) hypothesis postulates that many common NCDs originate in utero by re-programming fetal physiological and metabolic responses with lifelong consequences on organ and tissue function. The biological signatures linked to early life adversity are also transmitted across generations. Natural disaster and nutritional birth cohorts as well as experimental studies have demonstrated that remote ancestral adverse experiences increase the risk of metabolic, cardiac, and renal disease, and mental illness with a sex-specific bias. These adverse health outcomes are linked to epigenetic regulation, including altered microRNA (miRNA) expression.

Here, we performed a longitudinal rat cohort study to examine the impact of recurrent stress reaching back across four generations (F0-F3) on lifetime health trajectories. We hypothesized that multigenerational prenatal stress (MPS) in the F4 generation would lead to a behavioural phenotype of sex-specific stress vulnerability and resilience at young and old age. Moreover, we proposed particular vulnerability to NCDs in old age in association with up-stream epigenetic and down-stream metabolic biomarker signatures.

Unbiased deep sequencing of frontal cortex revealed that MPS altered expression of microRNAs and their target genes involved in synaptic plasticity, stress regulation, immune function, and longevity. Multi-layer top-down deep learning metabolite enrichment analysis of urine markers revealed altered metabolic homeodynamics in MPS males. Thus, peripheral metabolic signatures may provide sensitive biomarkers of stress vulnerability and disease risk. Programming by MPS appears to be a significant determinant of lifetime mental health trajectories, physical wellbeing, and vulnerability to NCDs through altered epigenetic regulation.

Link: https://doi.org/10.18632/aging.102848

Alzheimer's disease is characterized by the presence of protein aggregates in the brain. These are misfolded and altered versions of proteins that can act as seeds for solid deposits to form and spread in the brain. These deposits are surrounded by a halo of toxic biochemistry that harms and eventually kills neurons. Amyloid-β aggregates are present in the early stages of the condition, while tau aggregates cause much greater harm and cell death in the later stages.

Alzheimer's disease is also an inflammatory condition, however, in which chronic inflammation and altered behavior of the central nervous system immune cells known as microglia is clearly very influential. The interaction between amyloid-β, tau, and inflammation is somewhat debated. One view is that early amyloid-β aggregation causes microglia to become dysfunction and inflammatory, and this behavior generates an environment of chronic inflammation that results in tau aggregation. Alternatively, amyloid-β accumulation may just be a side-effect of persistent infections that produce chronic inflammation in the brain. Both of these options might be true to varying degrees in different patients. It is quite challenging to pick apart the mechanisms of early Alzheimer's in humans, as it isn't feasible to open up large numbers of living brains to take a look at their biochemistry.

Today's research materials add support for the more complex picture of differing contributions and interactions of amyloid-β and inflammation from individual to individual. The scientists involved suggest that only some amyloid-β plaques will trigger inflammation, those in which the amyloid-β is mixed in with nucleic acids. No doubt the propensity for plaques to be so structured varies from individual to individual for reasons that have yet to be explored. This is all quite interesting, but it still runs into the problem that removal of amyloid-β doesn't seem to help Alzheimer's patients, even when accomplished early. That one point is the largest obstacle to any theory that involves amyloid-β generating chronic inflammation sufficient to advance the disease processes.

Connecting interferon, neuroinflammation and synapse loss in Alzheimer's disease

Amyloid plaques in the brains of people with Alzheimer's disease have a heterogeneous composition; for instance, some may also contain sugars, lipids, or nucleic acids. Previously, researchers found that amyloid fibrils with nucleic acids, but not those without them, triggered immune cells in the blood to produce type 1 interferon (IFN). IFN is a potent cytokine produced when immune cells sense nuclei acids, such as those that come from viral particles, in their environment. IFN triggers a beneficial inflammatory response that is the first line of defense against viral infections.

Researchers found that the same mouse brains that had amyloid plaques with nucleic acids also showed a molecular signature mimicking an antiviral IFN response. Further experiments revealed that nucleic acids in the plaques activated brain microglia, which produced IFN that in turn triggered a cascade of inflammatory reactions that led to the loss of synapses, the junctions between neurons through which they communicate. Synapse loss is a key part of neurodegeneration and can lead to memory loss and eventually dementia.

The accumulation of amyloid plaques in human brains is known to poorly correlate with the severity or duration of dementia. There are people without signs of dementia who harbor significant amounts of both amyloid plaques and tau tangles in their brains, but remarkably lack the robust microglial activation and inflammatory response that is associated with loss of synapses and neurons. "Our findings in mouse models suggest that it is plausible that plaques that accumulate in Alzheimer's disease patients and those in non-demented individuals differ in their content of nucleic acids. It is thus of great interest to examine more closely the molecular constituents of amyloid plaques in the brains of cognitively resilient individuals and compared them to those of Alzheimer's disease cases."

Type I interferon response drives neuroinflammation and synapse loss in Alzheimer disease

Type I interferon (IFN) is a key cytokine that curbs viral infection and cell malignancy. Previously, we have demonstrated a potent IFN immunogenicity of nucleic acid (NA)-containing amyloid fibrils in the periphery. Here, we investigated whether IFN is associated with β-amyloidosis inside the brain and contributes to neuropathology. An IFN-stimulated gene (ISG) signature was detected in the brains of multiple murine Alzheimer disease (AD) models, a phenomenon also observed in wild-type mouse brain challenged with generic NA-containing amyloid fibrils.

In vitro, microglia innately responded to NA-containing amyloid fibrils. In AD models, activated ISG-expressing microglia exclusively surrounded NA-positive amyloid β plaques, which accumulated in an age-dependent manner. Brain administration of recombinant IFNβ resulted in microglial activation and complement C3-dependent synapse elimination in vivo. Conversely, selective IFN receptor blockade effectively diminished the ongoing microgliosis and synapse loss in AD models. Moreover, we detected activated ISG-expressing microglia enveloping NA-containing neuritic plaques in post-mortem brains of AD patients. Gene expression interrogation revealed that IFN pathway was grossly upregulated in clinical AD and significantly correlated with disease severity and complement activation.

Researchers here show a small effect on life span in nematode worms resulting from an increase in the unfolded protein response in the endoplasmic reticulum in neurons. This is connected with lipophagy, a process that depletes lipids in these cells. In this context, it is worth mentioning that, as a general rule, small effect sizes in nematodes are not interesting from the perspective of producing therapies to extend healthy life for mammals. Short-lived species have life spans that are very plastic in response to environment circumstances and changes in the regulation of cellular housekeeping processes. Longer lived species exhibit far lesser changes in life span under the same circumstances. So a small effect size in nematodes will likely be indistinguishable in humans.

The homeostatic regulation of protein folding (proteostasis), which is monitored in specific subcellular compartments, is an integral player in stress resistance and longevity. The endoplasmic reticulum (ER), in particular, is a central regulator of stress monitoring as it controls nearly a third of the cell's proteins, provides an internal medium for lipid homeostasis and cell signaling, and communicates directly with all other organelles to maintain cellular secretion. Thus, cells have evolved numerous quality control machineries dedicated to protecting the ER both under basal and stressed conditions.

Notably, the ER has evolved three primary branches of its unfolded protein response (UPRER) to maintain proper secretion, protein folding, and lipid homeostasis. While these pathways have been intensively studied for the past two decades, much less is known about the adaptive responses of the ER under long-lived conditions. Work with the nematode C. elegans has shown that its cells become less capable in protein folding and also less able to induce stress responses to proteotoxicity with advanced age. Overexpression of xbp-1, specifically in neurons, extends organismal life span and increases ER stress tolerance in a cell nonautonomous manner. While the precise, small ER stress signal was not identified, small clear vesicles are required for this beneficial effect, which could be host to numerous neurotransmitters.

We hypothesized that induction of the UPRER in neurons, which reverses the age-dependent loss of ER proteostasis, also enacts a marked restructuring of ER morphology, which, in turn, imparts a beneficial metabolic change and promotes longevity. Although whole-organismal metabolic restructuring has been a topic of intense study in the aging field, much less is known about the adaptive responses of organelles in long-lived conditions. Here, we find that neuronal xbp-1 animals have notable ER restructuring and lipid depletion, and that these changes are distinct from chaperone induction. Thus, we argue that the beneficial effects of nonautonomous UPRER are dependent on two independent, yet equally important, arms of UPRER: the protein homeostasis arm, including chaperone induction, and the metabolic arm, which induces ER remodeling and lipophagy.

Link: https://doi.org/10.1126/sciadv.aaz1441

One of the more interesting findings of the past decade or so, as accelerometers allowed for a better calibration of exercise levels in epidemiological studies, is that even more mild levels of exercise are still quite well correlated with health and mortality in later life. The dose-response curve for exercise is steep when going from nothing to mild exercise, and then flattens out for moderate and greater exercise. In later life this is particularly pronounced, judging from the evidence at hand.

This investigation evaluated physical activity levels of 1,262 participants from the ongoing Framingham Offspring Study. Participants were an average age of 69 (54% women), and they were instructed to wear a device that objectively measured physical activity for at least 10 hours a day, for at least four days a week between 2011 and 2014. Participants were 67% less likely to die of any cause if they spent at least 150 minutes per week in moderate to vigorous physical activity - a goal recommended by the American Heart Association - compared to those who did not engage in more than 150 minutes per week of moderate to vigorous physical activity.

However, this investigation observed that, among the participants with an average age of 69, physical activity doesn't have to be strenuous to be effective. The researchers observed that each 30-minute interval of light-intensity physical activities - such as doing household chores or casual walking - was associated with a 20% lower risk of dying from any cause. Conversely, every additional 30-minutes of being sedentary was related to a 32% higher risk of dying from any cause.

Link: https://newsroom.heart.org/news/for-older-adults-more-physical-activity-could-mean-longer-healthier-lives

Today's open access research reports on two specific epigenetic changes observed in old individuals that act to reduce mitochondrial function. This joins an existing list of genes for which expression changes are known to impact mitochondrial function with age. A herd of hundreds of mitochondria are found in every cell, working to provide the cell with a supply of energy store molecules used to power its operations. They are the distant descendants of ancient symbiotic bacteria, now fully integrated into the cell. Loss of mitochondrial function is strongly implicated in the progression of aging and age-related diseases, particularly in energy-hungry tissues such as the brain and muscle.

Proximately, this loss of function is caused by changes in the expression of regulatory or functional proteins. Epigenetic regulation shifts with age in characteristic ways, for reasons that remain debated. While there is a good list of root cause molecular damage that leads to aging, connect those root causes to specific changes in gene expression relevant to downstream problems is quite challenging. It will be the work of decades yet to fill in the grand map of the biochemistry of the detailed progression of aging. This is why it is important for the research community to identify plausible points of intervention now, wherein it is faster to test and observe the outcome than to wait for full understanding.

Epigenetic change may or may not be a plausible point of intervention in the matter of mitochondria and aging. Which of these outcomes is the case should be revealed in the years ahead, via ongoing work on in vivo cellular reprogramming. In the petri dish, the process of reprogramming resets epigenetic markers in old cells and restores mitochondrial function. The hope of groups such as Turn.bio is that this can be made to happen, safely, in vivo as well as in vitro. Comprehensively restoring mitochondrial function throughout the body is a valuable goal, given what is known of the role of mitochondria in aging.

In Aging, Epigenetic Wet Blanket Douses Mitochondria

Researchers have discovered that reining in the expression of two epigenetic regulators could extend the "healthspan" - as opposed to merely the lifespan - of worms and mice. The scientists studied BAZ-2 and SET-6, proteins that read and write epigenetic signals, respectively. They found that levels of both proteins ramp up with age in both species, in turn dampening expression of genes involved in mitochondrial function. The resulting metabolic slowdown put worms off their food and they mated less, and it hastened memory loss in old mice. What about orthologs of these epigenetic proteins in humans? Their levels increased in the brain with age, and correlated with progression of Alzheimer's disease. The study reinforces current thinking that mitochondria are key to aging.

How do BAZ-2 and SET-6 hasten aging? The researchers found that the two proteins together bind to promoter regions of more than 2,000 genes, dampening their expression via histone methylation. Among these target genes were numerous nuclear-encoded mitochondrial genes. Through their repression of these genes, BAZ-2 and SET-6 sapped oxygen consumption and ATP production, and bungled critical stress responses that maintain mitochondrial proteostasis. The researchers extended their nematode findings to mammals, reporting that orthologs of BAZ-2 and SET-6 dampened expression of key mitochondrial genes in cultured mouse and human cells. Knocking out BAZ-2 in mice assuaged age-related decline in brain metabolism, weight gain, and spatial memory loss, but did not extend lifespan.

Next, the researchers accessed a gene-expression dataset of human prefrontal cortex samples from the Harvard Brain Tissue Resource Center, including 376 from people with late-onset Alzheimer's disease and 173 from nondemented elderly. Among the samples from cognitively normal people, levels of human homologs of BAZ-2 and SET-6 increased with age. Among those with Alzheimer's disease, the proteins correlated with Alzheimer's disease progression, and with reduced expression of mitochondrial genes.

Two conserved epigenetic regulators prevent healthy ageing

Here we report a conserved epigenetic mechanism underlying healthy ageing. Through genome-wide RNA-interference-based screening of genes that regulate behavioural deterioration in ageing Caenorhabditis elegans, we identify 59 genes as potential modulators of the rate of age-related behavioural deterioration. Among these modulators, we found that a neuronal epigenetic reader, BAZ-2, and a neuronal histone 3 lysine 9 methyltransferase, SET-6, accelerate behavioural deterioration in C. elegans by reducing mitochondrial function, repressing the expression of nuclear-encoded mitochondrial proteins. This mechanism is conserved in cultured mouse neurons and human cells.

Examination of human databases shows that expression of the human orthologues of these C. elegans regulators, BAZ2B and EHMT1, in the frontal cortex increases with age and correlates positively with the progression of Alzheimer's disease. Furthermore, ablation of Baz2b, the mouse orthologue of BAZ-2, attenuates age-dependent body-weight gain and prevents cognitive decline in ageing mice. Thus our genome-wide RNA-interference screen in C. elegans has unravelled conserved epigenetic negative regulators of ageing, suggesting possible ways to achieve healthy ageing.

Mitochondria are the power plants of the cell, responsible for producing the chemical energy store molecule adenosine triphosphate (ATP) that powers cellular operations. As such, most processes of interest in disease and regeneration have at least some indirect dependency on mitochondrial function. Researchers here note a potential connection between mitochondrial function and the inability of nerves to regrow following injury. They provide evidence for an adjustment to the way in which mitochondria behave in nerve cells, and in the connections between nerve cells called axons, to spur regeneration. This is an interesting approach to regenerative medicine, though clearly at a very early stage of exploration.

The cells of the body use a chemical compound called adenosine triphosphate (ATP) for fuel. Much of this ATP is made by cellular power plants called mitochondria. In spinal cord nerves, mitochondria can be found along the axons. When axons are injured, the nearby mitochondria are often damaged as well, impairing ATP production in injured nerves. "Nerve repair requires a significant amount of energy. Our hypothesis is that damage to mitochondria following injury severely limits the available ATP, and this energy crisis is what prevents the regrowth and repair of injured axons."

Adding to the problem is the fact that, in adult nerves, mitochondria are anchored in place within axons. This forces damaged mitochondria to remain in place while making it difficult to replace them, thus accelerating a local energy crisis in injured axons. One of the leading groups studying mitochondrial transport previously created genetic mice that lack the protein - called Syntaphilin - that tethers mitochondria in axons. In these "knockout mice" the mitochondria are free to move throughout axons.

When the researchers looked in three injury models in the spinal cord and brain, they observed that Syntaphilin knockout mice had significantly more axon regrowth across the injury site compared to control animals. The newly grown axons also made appropriate connections beyond the injury site. When the researchers looked at whether this regrowth led to functional recovery, they saw some promising improvement in fine motor tasks in mouse forelimbs and fingers. This suggested that increasing mitochondrial transport and thus the available energy to the injury site could be key to repairing damaged nerve fibers. To test the energy crisis model further, mice were given creatine, a bioenergetic compound that enhances the formation of ATP. Both control and knockout mice that were fed creatine showed increased axon regrowth following injury compared to mice fed saline instead. More robust nerve regrowth was seen in the knockout mice that got the creatine.

Link: https://www.ninds.nih.gov/News-Events/News-and-Press-Releases/Press-Releases/Boosting-energy-levels-within-damaged-nerves

Why do males of all species have a shorter life expectancy than that of females? There are numerous perspectives on this question, from viewing it as a natural evolutionary outgrowth of mating strategies, to the more mechanistic concerns of differences in metabolism, appetite for risk, and so forth. One popular hypothesis is that the Y chromosome is less capable of covering for mutational damage to the X chromosome than is a duplicate X chromosome. This will gender-bias the effects of inherited mutations on the evolution of longevity, and perhaps also magnify the effects of stochastic mutational damage occurring across a lifetime. Experiments in using male mice engineered to have two X chromosomes provide supporting evidence for the proposition, and, as noted here, the balance of the rest of the evidence in the literature tends to follow along in that support.

Researchers analysed all available academic literature on sex chromosomes and lifespan - and they tried to establish whether there was a pattern of one sex outliving the other that was repeated across the animal kingdom. Specifically, they wanted to test the 'unguarded X hypothesis' which suggests that the Y chromosome in heterogametic sexes - those with XY (male) sex chromosomes rather than XX (female) sex chromosomes - is less able to protect an individual from harmful genes expressed on the X chromosome. The hypothesis suggests that, as the Y chromosome is smaller than the X chromosome, and in some cases absent, it is unable to 'hide' an X chromosome that carries harmful mutations, which may later expose the individual to health threats. Conversely, there is no such problem in a pair of homogametic chromosomes (XX), where a healthy X chromosome can stand in for another X that has deleterious genes to ensure those harmful genes aren't expressed, thus maximising the length of life for the organism.

After examining the lifespan data available on a wide range of animal species, it appears that the unguarded X hypothesis stacks up. This is the first time that scientists have tested the hypothesis across the board in animal taxonomy; previously it was tested only within a few groups of animals. "We looked at lifespan data in not just primates, other mammals and birds, but also reptiles, fish, amphibians, arachnids, cockroaches, grasshoppers, beetles, butterflies, and moths, among others. And we found that across that broad range of species, the heterogametic sex does tend to die earlier than the homogametic sex, and it's 17.6 per cent earlier on average."

Interestingly, the researchers observed this same pattern in the classes of animals possessing their own unique pair of sex chromosomes that are the reverse of all other animals. In birds, butterflies and moths, it is the male of the species that has the homogametic sex chromosomes (denoted by ZZ) while the female has the heterogametic chromosomes (ZW). Female birds, butterflies, and moths were usually found to die earlier than their male counterparts, giving credence to the unguarded X hypothesis - although strictly speaking, it's an unguarded Z in this case.

Link: https://newsroom.unsw.edu.au/news/science-tech/why-men-and-other-male-animals-die-younger-it%E2%80%99s-all-y-chromosome

All cancerous cells share a single potential vulnerability: they must continually lengthen their telomeres in order to replicate. Most cancers abuse telomerase in order to do this, while a minority use the alternative lengthening of telomeres (ALT) mechanisms. Normally, in humans, telomerase is only present in stem cell populations, those that must maintain themselves across a life span. It is not present in somatic cells, the vast majority of any tissue. The primary activity of telomerase is to extend the repeated DNA sequences known as telomeres, found at the ends of chromosomes. Telomeres are a part of the mechanism by which somatic cells are limited in the number of times they can divide; a little of the telomere length is lost with each cell division, and when telomeres are short, cells self-destruct or become senescent.

Thus in any normal tissue, only a small population of stem cells is privileged to replicate more or less indefinitely. These cells generate daughter somatic cells that have a finite lifetime. This structure is the way in which higher life forms have evolved to reduce the risk of cancer to a sufficiently low level. Cancer arises due to random mutations that enable cells to replicate uncontrollably, and that must, by necessity, include a way to lengthen telomeres. Having the majority of cells in the body limited in life span, reduces the risk of any given cell accumulating the right collection of mutations to trigger cancer.

When looking at progress towards the medical control of cancer, the most efficient way forward is to focus on targeting mechanisms that are shared by all cancers, or at least by a very large subset of cancers. The most economical way forward is to find a class of therapy that can be applied to many cancers with minimal adjustment - there are hundreds of varieties of cancer, and only so many researchers and only so much funding for research. The best of the potential approaches that are presently known is to find some way to interfere in telomere lengthening. This is why the research materials here are interesting: any viable way to suppress telomerase activity is one sizable portion of a universal cancer therapy.

Chemists inhibit a critical gear of cell immortality

Researcher have developed a promising molecular tool that targets and inhibits one of cell immortality's underlying gears: the enzyme telomerase. This enzyme is found overexpressed in approximately 90% of human cancer cells and has become an important subject of study for cancer researchers. Normal cells have the gene for telomerase, but it typically is not expressed. "Telomerase is the primary enzyme that allows cancer cells to live forever. We want to short-circuit this immortality. Now we have designed a first-of-its-kind small molecule that irreversibly binds to telomerase, shutting down its activity. This mechanism offers a new pathway for treating cancer and understanding cellular aging."

The big idea for the small molecule design came from nature. A decade ago, the researchers were intrigued by the biological activity of chrolactomycin, which is produced by bacteria and has been shown to inhibit telomerase. The team used chrolactomycin as a starting point in the design of their small molecules. They produced more than 200 compounds over the years, and the compound they call NU-1 was the most effective of those tested. Its synthesis is very efficient, taking fewer than five steps. "NU-1 inhibits telomerase unlike anything that came before it. It does this by forming a covalent bond. Another advantage of NU-1 is that its molecular structure should enable scientists to add cargo, such as a therapeutic."

Targeted Covalent Inhibition of Telomerase

Telomerase is a ribonuceloprotein complex responsible for maintaining telomeres and protecting chromosomal integrity. The human telomerase reverse transcriptase (hTERT) is expressed in ∼90% of cancer cells where it confers the capacity for limitless proliferation. Along with its established role in telomere lengthening, telomerase also serves noncanonical extra-telomeric roles in oncogenic signaling, resistance to apoptosis, and enhanced DNA damage response. We report a new class of natural-product-inspired covalent inhibitors of telomerase that target the catalytic active site.

It is well known that excess visceral fat tissue is harmful to health over the long term. A sizable amount of this harm stems from mechanisms that act to generate chronic inflammation. These include an accelerated generation of lingering senescent cells, DNA debris from dead fat cells, signaling from normal fat cells that is similar to that secreted by infected cells, and so forth. Researchers here focus on the link between visceral fat and loss of cognitive function, showing that particular inflammatory signal is influential in causing the central nervous system immune cells known as microglia to change their behavior for the worse, thereby harming the function of neurons in the brain. There is a great deal of other evidence pointing towards the importance of inflammatory and senescent microglia in the development of neurodegenerative conditions; chronic inflammation is a noteworthy component of the aging process, and to the extent it can be minimized, such as by maintaining a low level of visceral fat tissue, individuals tend to have a better prognosis.

Scientists have shown one way in which visceral fat is bad for brains is by enabling easy, excessive access for the proinflammatory protein signal interleukin-1 beta. The brain typically does not see much of this interleukin-1 beta, but researchers have found that visceral adiposity generates high, chronic levels of the signal that in turn over-activate the usually protective microglia, the resident immune cells in our brain. A bit like a smoldering pot, this chronic inflammation from visceral fat prompts formation of inflammasome complexes that further amplify the immune response and inflammation. The protein NLRP3 is a core component of the inflammasome complex in the fat, and it's what promotes the production and release of interleukin-1 beta by fat cells, and stokes the inflammation fire. It was known these reactions were causing problems in the body, and now the scientists have evidence they are causing problems in the brain.

To explore brain effects, the scientists knocked NLRP3 out of mice and found the mice were protected against obesity-induced inflammation of the brain and the cognitive problems that can result. They also transplanted visceral adipose tissue from obese mice and obese mice missing NLRP3 into lean mice recipients and found the transplant from the NLRP3 knockout mouse had essentially no effect. But the transplant from the obese but genetically intact mice increased levels of interleukin-1 beta in the hippocampus, a center of learning and memory in the brain, and impaired cognition.

Microglia typically function as watchdogs, constantly surveilling and roaming the brain, eliminating dead cells and other debris as well as a myriad of other tasks like forming and pruning connections between neurons. Microglia also have receptors for interleukin-1 beta, and the protein, whose many actions include promoting inflammation, easily passes through the protective blood brain barrier. Microglia's helpful - or harmful - actions likely result from signals they are exposed to, and another thing interleukin-1 beta appears to do is prompt microglia to wrap around synapses, possibly exerting damaging pressure and/or releasing substances that actually interfere with conversations between neurons. In the absence of disease, microglia also are known to embrace synapses but to release good things like brain-derived neurotrophic factor, which is like fertilizer for these invaluable connections.

Link: https://jagwire.augusta.edu/visceral-fat-delivers-signal-to-the-brain-that-hurts-cognition/

Therapies using mesenchymal stem cells are quite widely used at the present time, but efficacy varies considerably, clinic by clinic, even between those groups ostensibly taking exactly the same approach to cell source and methodologies of treatment. Working with cells isn't easy, and very small differences in protocol can lead to large differences in the behavior and type of cells that result. The majority of such treatments see transplanted cells die quite quickly, but their signaling produces effects on native cell behavior. Suppression of chronic inflammation is the most consistent outcome, but improvements in regeneration, or in functional capacity in older people, are harder to obtain with any great reliability. Some groups claim to be able to make transplanted mesenchymal stem cells engraft and survive in large enough numbers to make a difference, but this isn't common. Thus this is a field of medicine in which there remains considerable room for improvement.

Adipose tissue derived stem cells (ADSCs) are mesenchymal stem cells identified within subcutaneous tissue at the base of the hair follicle (dermal papilla cells), in the dermal sheets (dermal sheet cells), in interfollicular dermis, and in the hypodermis tissue. These cells are expected to play a major role in regulating skin regeneration and aging-associated structural deficits. ADSCs are known to proliferate and differentiate into skin cells to repair damaged or dead cells, but also act by an autocrine and paracrine pathway to activate cell regeneration and the healing process.

During wound healing, ADSCs have a great ability in migration to be recruited rapidly into wounded sites added to their differentiation towards dermal fibroblasts (DF), endothelial cells, and keratinocytes. Additionally, ADSCs and DFs are the major sources of the extracellular matrix (ECM) proteins involved in maintaining skin structure and function. Their interactions with skin cells are involved in regulating skin homeostasis and during healing.

The evidence suggests that their secretomes ensure: (i) The change in macrophages inflammatory phenotype implicated in the inflammatory phase, (ii) the formation of new blood vessels, thus promoting angiogenesis by increasing endothelial cell differentiation and cell migration, and (iii) the formation of granulation tissues, skin cells, and ECM production, whereby proliferation and remodeling phases occur. These characteristics would be beneficial to therapeutic strategies in wound healing and skin aging and have driven more insights in many clinical investigations. ADSCs fulfill the general accepted criteria for cell-based therapies, but nonetheless still need further investigations into their efficiency, taking into consideration the host-environment and patient-associated factors.

Link: https://doi.org/10.3390/ijms21041306

Mitochondria are the power plants of the cell, hundreds of them working to generate copies of the energy store molecule ATP, used to power cellular operations. Declining mitochondrial function is thought important in aging, disruptive of the ability of cells and tissues to function correctly, and a large body of scientific literature supports a contributing role for mitochondrial dysfunction in many age-related conditions. With advancing age, changes in gene expression in cells, reactions to the deeper damage and dysfunction of aging, lead to mitochondria that are both inefficient in producing ATP and resistant to clearance by the quality control mechanisms of mitophagy. It is also possible for damage to mitochondrial DNA to produce cells overtaken by malfunctioning mitochondria, and these problem cells make an outsized contribution to oxidative stress in tissues.

What can be done about this? There are many potential strategies, with various degrees of effectiveness. At present there is evidence from NAD+ upregulation and mitochondrially targeted antioxidants to suggest that means of restoring mitophagy can improve mitochondrial function. These particular approaches may be little more effective than exercise in achieving this goal in humans, however. The evidence for better outcomes is still mixed and limited. The SENS Research Foundation is working on copying mitochondrial genes into the cell nucleus to ensure that mitochondrial DNA damage doesn't result in dysfunctional cells, but this doesn't solve the other half of the problem. Reprogramming of cells from old tissues restores youthful epigenetic patterns and mitochondrial function, and a number of groups are working towards the development of reprogramming techniques that can be used in vivo. And so forth.

One of the more interesting findings of recent years is that mitochondria can be ingested by cells and put to work. Cells transfer mitochondria between one another under some circumstances. Further, there appears to be a sizable contingent of free-roaming mitochondria outside cells, perhaps employed as a form of intracellular signaling. Thus, why not periodically infuse an older patient with large amounts of pristine, undamaged mitochondria, to be taken up by cells and put to work? Researchers here demonstrate that this approach to therapy results in functional improvements in older mice.

Improvement of cognitive and motor performance with mitotherapy in aged mice

Mitochondrial dysfunction, including decreased oxidative phosphorylation capability and increased reactive oxygen species (ROS) production, is substantially responsible for aging and age-related features. Studies in various organisms, such as nematodes, Drosophila, rodents, and humans, have strongly supported that aging is closely associated with mitochondrial dysfunction. Thus, protection of the mitochondrial structure or stimulation of mitochondrial function is considered as practical ways in anti-aging. However, since most of the mitochondrial damage is irreversible during aging process, the agents can always provide limited protection.

Mitochondrial therapy (mitotherapy) is to transfer functional exogenous mitochondria into mitochondria-defective cells for recovery of the cell viability and consequently, prevention of the disease progress. Accumulating evidence has indicated that exogenous mitochondria can directly enter animal tissue cells for disease therapy following local and intravenous administration. In our recent reports, systemic injection of isolated mitochondria could reduce liver injury induced by acetaminophen and high-fat diet through improving hepatocyte energy supply and decreasing oxidative stress. Therefore, we assumed that the mitochondria isolated from young animals (young mitochondria) into aged ones might play a role in anti-aging.

In this study, we intravenously administrated the young mitochondria into aged mice to evaluate whether energy production increase in aged tissues or age-related behaviors improved after the mitochondrial transplantation. The results showed that heterozygous mitochondrial DNA of both aged and young mouse coexisted in tissues of aged mice after mitochondrial administration, and meanwhile, ATP content in tissues increased while reactive oxygen species (ROS) level reduced. Besides, the mitotherapy significantly improved cognitive and motor performance of aged mice. Our study, at the first report in aged animals, not only provides a useful approach to study mitochondrial function associated with aging, but also a new insight into anti-aging through mitotherapy.

Both exercise and the practice of calorie restriction produce benefits to health in large part via an increased or more efficient operation of cellular maintenance processes such as autophagy and the ubiquitin-proteasome system, both of which act to recycle damaged or waste proteins and cell structures, improving cell function. Many research groups are involved in investigating the details of these metabolic responses, in search of ways to mimic some fraction of the beneficial effects of exercise or calorie restriction. The work noted here is an example of the type, focused on increased levels of cAMP as an important part of the process.

It is already well known that exercise has many salutary effects, but= new findings hint at the possibility that exercise and fasting could also help reduce the risk of developing conditions associated with the accumulation of misfolded proteins, such as Alzheimer's and Parkinson's. That possibility, however, remains to be explored. In their experiments, the researchers analyzed the effects of exercise on cells obtained from the thigh muscles of four human volunteers before and after vigorous biking. Following exercise, the proteasomes of these cells showed dramatically more molecular marks of enhanced protein degradation, including greater levels of cAMP. The same changes were observed in the muscles of anesthetized rats whose hind legs were stimulated to contract repeatedly. Fasting - even for brief periods - produced a similar effect on the cells' protein-breakdown machinery. Fasting increased proteasome activity in the muscle and liver cells of mice deprived of food for 12 hours, the equivalent of an overnight fast.

In another round of experiments, the researchers exposed the liver cells of mice to glucagon, the hormone that stimulates production of glucose as fuel for cells and tissues during periods of food deprivation or whenever blood sugar levels drop. The researchers observed that glucagon exposure stimulated proteasome activity and enhanced the cells' capacity to destroy misfolded proteins. Exposure to the fight-or-flight hormone epinephrine produced a similar effect. Epinephrine, also known as adrenaline, is responsible for stimulating the liver and muscle to mobilize energy reserves to boost heart rate and muscle strength during periods of physiologic stress. Liver cells treated with epinephrine showed marked increases in cAMP, as well as enhanced 26S proteasome activity and protein degradation. Epinephrine exposure also boosted proteasome activity - a marker of protein degradation - in the hearts of living rats. Similarly, when researchers exposed mouse kidney cells to vasopressin - the antidiuretic hormone that helps the body retain water and prevents dehydration - they observed higher levels of protein degradation as well.

Taken together, these findings demonstrate that the rate of protein degradation can rise and fall swiftly in a variety of tissues in response to shifting conditions, and that such changes are mediated by fluctuations in hormone levels. This response was surprisingly rapid and short-lived, the scientists noted. For example, exposure to the antidiuretic hormone triggered protein breakdown in kidney cells within five minutes and subsided to pre-exposure levels within an hour, the experiments showed. The findings show that the diverse set of hormones that stimulate cAMP appear to share a common mechanism that alters the composition of cells. These have long been known to modify gene expression, but this latest research reveals they also play a critical role in cellular housecleaning by disposing of proteins that are no longer needed.

Link: https://news.harvard.edu/gazette/story/2019/02/exercise-fasting-shown-to-help-cells-shed-defective-proteins/

Hypoxia inducible factor 1 (HIF-1) is known to be important in skin aging, involved in the regulation of numerous processes relevant to the maintenance and structure of skin tissue. One of these is the growth of blood vessels that is required for regeneration to take place following injury. The dysfunction of HIF-1 signaling and consequent dysfunction in blood vessel regrowth is a feature of the varieties of non-healing wounds that are observed in older people. The open access paper here reviews what is known of HIF-1 in this context.

Oxygen is key to many processes of life and is involved in all stages of wound healing in the skin, with many cells and pathways being reactive to changes in oxygen concentration. Following injury to the skin, disruption of the vasculature results in a hypoxic environment, which is further exacerbated by high oxygen consumption through the cells present at the edge of the wound. Hypoxia has been found to have myriad effects on cells and their function, such as inducing greater dermal fibroblast proliferation and production of TGF-β1. Furthermore, hypoxia has been shown to promote in vitro keratinocyte motility and leads to the secretion of several growth factors. These are but a few of the many roles acute hypoxia plays in the induction of skin healing, and although hypoxia is necessary for regeneration, a return to normoxic conditions is eventually required.

With hypoxia being of such importance to regeneration of the skin, the HIF pathways have drawn much attention. Hypoxia-inducible factors (HIFs) are pleiotropic key regulators of oxygen homeostasis. HIF-1 consists of two subunits: HIF-1α (or its analogs HIF-2α and HIF-3α) and HIF-1β, which bind to acquire the transcriptional capabilities that promote cell survival during hypoxia. Additionally, HIF-1 serves as a crucial modulator in the homeostatic processes during hypoxia by increasing vascularization and regulating anaerobic respiration.

While HIF-1 is undoubtedly important for wound healing, excessive expression of HIF-1 can lead to unwanted fibroproliferation in the form of keloids and hypertrophic scarring. Conversely, deficits in HIF-1 signaling can lead to inadequate wound healing. Chronic wounds are often characterized by a constant, nonresolving inflammatory phase, causing proinflammatory signaling cascades to persist. This results in higher levels of proteases that work to destroy extracellular matrix components and other molecules beneficial to wound healing, preventing the proliferation and tissue remodeling phases from advancing normally. Studies have identified HIF-1 signaling as one of the underlying causes behind many nonhealing wounds. Common examples of chronic wounds include diabetic wounds, pressure ulcers, and aged wounds.

The structure and pathophysiology of aged skin differs greatly from the skin in younger individuals. These discrepancies are responsible for the delayed healing found in aged skin, many of which are the result of irregular HIF-1 signaling. Over the past decade, extensive studies have examined the expression levels of HIF-1 in the aged compared with the young, and how regeneration was affected. One of the major observations of aged wound healing is that there is significantly lesser neovascularization following ischemia, impeding recovery. Neovascularization in humans occurs through both angiogenesis, the sprouting of new vessels from old ones, and vasculogenesis, the formation of new vessels by migration and aggregation of endothelial progenitor cells.

HIF-1α signaling has been shown to regulate both of these processes through transcription of cytokines such as SDF-1α. An improved understanding of the regulation of molecular mediators, such as HIF-1α and PHD, will allow for manipulation of the various factors underlying delayed wound healing in the aged. The findings highlighted in this may facilitate the development of potential therapeutic approaches involved in the alteration of cellular dynamics and aging.

Link: https://doi.org/10.1089/wound.2018.0912

The central nervous system is separated from the rest of the body by the blood-brain barrier, a layer of specialized cells wrapping blood vessels in the brain. These only allow certain molecules and cells to cross back and forth, and so the biochemical and cellular environment of the brain can be quite different from that of tissues it interacts with connected to. The brain even has its own distinct immune system: microglia, for example, are innate immune cells analogous to macrophages elsewhere in the body. Microglia are involved in an arguably broader range of activities than is the case for macrophages. They support core functions in the brain, such as via participation in the processes of synaptic remodeling.

A great deal of evidence points towards chronic inflammation as an important contributing cause of neurodegenerative conditions. Inflammation is beneficial when temporary, a necessary part of the immune response, but chronic inflammation that fails to resolve is a dysfunction of the immune system. Inflammatory microglia are a part of this chronic inflammation, and consequently they are also implicated in neurodegenerative conditions.

In all of this, there is a little of microglia being led into bad behavior by a preexisting inflammatory environment, joining in to make it worse, and a little of microglia becoming inflammatory (or even senescent and thus highly inflammatory) as a result of processes of damage in the brain, and thereby generating an inflammatory environment. Either will lead to the results observed in today's open access research, in which microglia are shown to contribute to dysfunction of the blood-brain barrier. This is one of the early features of neurodegeneration. When the blood-brain barrier leaks, inappropriate cells and molecules cross into the brain, causing disruption and adding to the burden of inflammation as immune cells respond to the invasion.

Two sides of a coin: Our own immune cells damage the integrity of the blood-brain barrier

A new study shows that microglia - the resident immune cells of the brain - initially protect the blood-brain barrier from damage due to "systemic inflammation," a condition of chronic inflammation associated with factors like smoking, ageing, and diabetes, and leading to an increased risk of neurodegenerative disorders. However, these same microglia can change their behavior and increase the blood-brain barrier permeability, thereby damaging it.

A key point of interest was the systemic inflammation induced by injecting the mice with an inflammation-inducing substance. Such injections resulted in the movement of microglia to the blood vessels and increased the permeability of the blood-brain barrier within a few days. Then, the microglia initially acted to protect the blood-brain barrier and limit increases in permeability, but as inflammation progressed, the microglia reversed their behavior by attacking the components of the blood-brain barrier, thus increasing the barrier's permeability. The subsequent leakage of molecules into the brain had the potential to cause widespread inflammation in the brain and consequent damage to neurons.

Uncontrolled inflammatory responses in the brain can cause a range of cognitive disorders and adverse neurological effects, and drugs that target microglia may help patients avoid such problems by preserving the integrity of the blood-brain barrier. More studies are required to understand more about the processes underlying the microglial behaviors observed in this study. Nevertheless, the study's results offer hope for the development of therapies that could "force" microglia to promote blood-brain barrier integrity and prevent microglia from transitioning to behaviors that damage the barrier.

Dual microglia effects on blood brain barrier permeability induced by systemic inflammation

Microglia are active surveyors of brain parenchyma with important roles in sculpting and coordinating neural circuits in healthy brains that respond rapidly to form a range of reactive phenotypes in brain infection and damage. Activated microglia play roles in a range of acute and neurodegenerative diseases, where they can help clear neuronal damage by phagocytosis, but can also contribute to disease progression by releasing molecules that can initiate a neuroinflammatory states. Microglia can also respond to peripheral inflammatory diseases.

A key question is how microglia change phenotypes when the primary pathological insult resides in the peripheral organs and systemic circulation. Determining how these systemic and neuronal inflammatory responses are linked may help reduce the deleterious impact of systemic immune activation and inflammation on cognitive function and susceptibility to brain disease. The blood-brain barrier (BBB) represents a major pathway by which systemic inflammation and immune responses potentially interact with the brain microenvironment.

The goal of this study was to examine the role of microglia in responding to systemic infection and inflammation, and its contribution to BBB integrity. Using two different models of peripheral inflammation, MRL/lpr mice and mice treated for 7 days with lipopolysaccharide, we demonstrated that resident brain microglia migrate to cerebral vessels during systemic inflammation in response to the release of the chemokine CCL5 from endothelial cells. This triggers microglial cells to express CLDN5 and to infiltrate through the neurovascular unit, thus contacting endothelial cells and forming tight junctions to maintain BBB integrity. Consistently, partial microglial ablation or blocking CCL5 signaling, actually increased BBB permeability during the early stages of inflammation.

The work noted here is one of a number of lines of development focused on handheld bioprinters capable of depositing tissue-like structures in situ, directly onto an injury. This is a promising approach to tissue engineering to enhance regeneration, allowing regrowth of tissues where it would not normally take place. It is interesting to compare the work on severe muscle injury here with recent efforts to enhance skin regeneration using a somewhat different handheld bioprinting tool.

Researchers recently developed a handheld 3D bioprinter that could revolutionize the way musculoskeletal surgical procedures are performed. The bioprinter enables surgeons to deposit scaffolds - materials to help support cellular and tissue growth - directly into the defect sites within weakened skeletal muscles. This allows proper filling of the cavity with fibrillar scaffolds in which fibers resemble the architecture of the native tissue. The scaffolds from the bioprinter adhere precisely to the surrounding tissues of the injury and mimic the properties of the existing tissue, eliminating the need for any suturing.

Current methods for reconstructive surgery have been largely inadequate in treating volumetric muscle loss. As a result, 3D printing technology has emerged as an up and coming solution to help reconstruct muscle. "A good solution currently does not exist for patients who suffer volumetric muscle loss. A customizable, printed gel establishes the foundation for a new treatment paradigm can improve the care of our trauma patients."

Existing 3D bioprinting technology is not without its problems. Implanting the hydrogel-based scaffolds successfully requires a very specific biomaterial to be printed that will adhere to the defect site. While 3D bioprinted scaffolds mimicking skeletal muscles have been created in vitro, they have not been successfully used on an actual subject. A handheld bioprinter approach fixes the problem. The bioprinter prints gelatin-based hydrogels - known as "bioink" - that have been proven to be effective in adhering to defect sites of mice with volumetric muscle loss injury. The mice showed a significant increase in muscle hypertrophy following the therapy.

Link: https://today.uconn.edu/2020/02/3d-printers-developed-treat-musculoskeletal-injuries/

Researchers here apply modern genomics approaches to assessing the ability of calorie restriction to slow the progression of aging. As is usually the case, beyond greater understanding of the complexities of the metabolic response to calorie restriction, the goal is to find potential points of intervention that have as yet gone unremarked. Single genes where expression might be changed in order to mimic some fraction of the response to a lower calorie intake. Taken more broadly, exploration that might lead to the development of novel calorie restriction mimetics represents a sizable fraction of all present work on intervention in the aging process. It isn't clear that it merits that much of a focus, given that the practice of calorie restriction doesn't have anywhere near the same size of effect in long-lived species such as our own as is the case in short-lived species such as the rats used here.

Aging is the highest risk factor for many human diseases, including cancer, dementia, diabetes, and metabolic syndrome. Caloric restriction has been shown in animal models to be one of the most effective interventions against these age-related diseases. And although researchers know that individual cells undergo many changes as an organism ages, they have not known how caloric restriction might influence these changes.

In a new paper, researchers compared rats who ate 30 percent fewer calories with rats on normal diets. The animals' diets were controlled from age 18 months through 27 months. (In humans, this would be roughly equivalent to someone following a calorie-restricted diet from age 50 through 70). At both the start and the conclusion of the diet, the researchers isolated and analyzed a total of 168,703 cells from 40 cell types in the 56 rats. The cells came from fat tissues, liver, kidney, aorta, skin, bone marrow, brain, and muscle. In each isolated cell, the researchers used single-cell genetic-sequencing technology to measure the activity levels of genes. They also looked at the overall composition of cell types within any given tissue. Then, they compared old and young mice on each diet.

Many of the changes that occurred as rats on the normal diet grew older didn't occur in rats on a restricted diet; even in old age, many of the tissues and cells of animals on the diet closely resembled those of young rats. Overall, 57 percent of the age-related changes in cell composition seen in the tissues of rats on a normal diet were not present in the rats on the calorie restricted diet. Some of the cells and genes most affected by the diet related to immunity, inflammation, and lipid metabolism. The number of immune cells in nearly every tissue studied dramatically increased as control rats aged but was not affected by age in rats with restricted calories. In brown adipose tissue - one type of fat tissue - a calorie-restricted diet reverted the expression levels of many anti-inflammatory genes to those seen in young animals.

When the researchers homed in on transcription factors - essentially master switches that can broadly alter the activity of many other genes - that were altered by caloric restriction, one stood out. Levels of the transcription factor Ybx1 were altered by the diet in 23 different cell types. The scientists believe Ybx1 may be an age-related transcription factor and are planning more research into its effects.

Link: https://www.salk.edu/news-release/eat-less-live-longer/

The thymus is where T cells of the adaptive immune system mature. Thymocytes are created by hematopoietic stem cells in the bone marrow and migrate to the thymus, where they undergo a process of change and selection to become T cells capable of deploying an immune response against pathogens and harmful cells, but not against healthy cells. Unfortunately, the active thymic tissue that guides this process atrophies with age in process known as involution. By the age of 50 most people have little functional thymic tissue left, and as a consequence the production of new T cells is greatly reduced. This loss of reinforcements is a major contribution to the age-related decline of the adaptive immune system. Without replacements, it becomes a cluttered mess of exhausted, senescent, and misconfigured cells. The overall number of T cells stays much the same, but their quality and behavior declines precipitously.

Given this, regrowth of active thymic tissue is an important goal for the rejuvenation research community. Several approaches have been demonstrated to achieve this goal in older mice, resulting in a restored production of T cells - with the caveat that if lymph nodes are too damaged by age, these new cells cannot sufficiently coordinate to improve immune function. Castration, sex-steroid ablation, delivery of recombinant KGF, delivery of growth hormone, and upregulation of FOXN1 are among the methods of thymic regrowth that work to varying degrees and with varying reliability in animal studies. Of those, sex-steroid ablation and growth hormone have interesting human data, while a human trial of KGF failed to produce results, probably because the dose was too low.

Of late, researchers have suggested that the age-related atrophy of the thymus is driven by chronic inflammation, a mirror of some infectious disease processes in which the thymus is damaged and reduced by the inflammation associated with persistent pathogens. Since the chronic inflammation of aging results to a large degree from rising levels of senescent cells in tissues, this suggests that senolytic therapies - or other means to control the inflammation of aging - might slow thymic involution to a sizable enough degree to be interesting.

Implications of Oxidative Stress and Cellular Senescence in Age-Related Thymus Involution

Despite the fundamental requirement for lifelong establishment and maintenance of an overall effective and adequate defense against pathogens, the function of the immune system deteriorates with age, affecting both innate and adaptive immune responses (immunosenescence). The thymus, which reaches its maximal size and T cell output during early postnatal life, exhibits early thymic involution, a phenomenon that becomes even more prominent with advancing age. Although the size of the human thymus seems to remain unchanged throughout life under normal conditions, in other vertebrates, it declines during aging. Nevertheless, in almost all vertebrates having a thymus, thymic cellularity is progressively decreased and replaced by adipose tissue over time, resulting in perturbation of the normal tissue architecture. Since T cell production is proportional to thymic epithelial tissue mass, thymic involution results in significant loss of its capability for de novo generation of immunocompetent T cells. The net outcome is a decline in frequency and function of naïve T cells, leading to a restricted T cell repertoire in the periphery.

Even though age-associated thymic regression represents one of the most recognizable features of the aging immune system, the underlying mechanisms are not well understood. Several candidates have been proposed, suggesting that thymic regression involves the interplay of various and different mechanisms; interestingly, there are lines of evidence that in this complex process, the thymic stroma and especially the TECS are the most sensitive compartment. A number of studies reported that sex steroid hormones, and especially androgens, contribute to age-associated thymic involution. This notion was based on the observations (a) that thymic involution, although beginning in early postnatal life, is more pronounced with the onset of puberty when sex steroid levels increase and (b) that high doses of sex steroid administration cause degeneration of the thymus.

Numerous studies have also implicated the growth hormone- (GH-) insulin-like growth factor- (IGF-) I axis in thymus regression. Both hormones promote thymic growth, and lately, GH has been used as an alternative strategy to rejuvenate the thymus in certain immunodeficiency disorders associated with thymic atrophy. GH and IGF-I have been also considered as regulators of age-associated thymic involution, since GH production declines with age. However, the effects of hormone treatment on thymus size in older mice are limited, implying that there are other factors that prevent thymic atrophy.

The phenomenon of infection-induced inflammation and consequently thymus regression has also been reported; in human studies as well as in animal experimental models, infections with pathogens led to thymic atrophy, although the underlying mechanisms have not been extensively studied. Lately, a new player suggested to be involved in accelerated thymus involution and dysfunction with age is oxidative stress. Notwithstanding that the generation of reactive oxygen metabolites is an integral feature of normal cellular metabolism, the accumulation of such genotoxic and proteotoxic oxygen-derived by-products seems to exert detrimental effects on thymic tissue. Contrariwise, genetic or biochemical enhancement of antioxidant activity has been proven to ameliorate thymic atrophy.

Similarly, oxidative damage is also a well-documented inducer of cellular senescence, a state of permanent cell cycle arrest. The accumulation of senescent cells maintains an inflammatory milieu (inflammaging) that causes tissue remodeling, affects the regenerative potential and proper function of tissues/organs due to exhaustion of progenitor and stem cells, and, ultimately, promotes aging and age-related pathologies. Considering that (1st) oxidative stress has been linked to both the induction of cellular senescence and thymic involution and (2nd) aging is characterized by accumulation of senescent cells as well as a decline in thymus function, it is not unreasonable to assume that cellular senescence may exert a critical role in the induction of thymic involution, with oxidative stress being the common denominator. Indeed, recent evidence, from human and animal studies, supports this notion.

Aging is accompanied by a reduction in the density of capillary networks throughout the body, for reasons that are not well understood in depth. The regulation of angiogenesis, the processes of blood vessel formation, is observed to change for the worse, but why does this happen? Which of the underlying forms of accumulating molecular damage cause this? Another important question is the degree to which this loss contributes to specific functional declines, such as that of muscle tissue. Researchers here report on the development of an animal model in which capillary density is first reduced, and then somewhat restored via resistance exercise. There is a clear negative effect on muscle function as a result of capillary loss, suggesting that this is an important factor in the loss of strength that accompanies aging. Finding ways to promote capillary network regrowth in older individuals should be a priority for the regenerative medicine community.

To what extent microvascular rarefaction contributes to impaired skeletal muscle function remains unknown. Our understanding of whether pathological changes in the microcirculation can be reversed remains limited by a lack of basic physiological data in otherwise healthy tissue. The principal objectives here were to: (1) quantify the effect of random microvascular rarefaction on limb perfusion and muscle performance, and (2) determine if these changes could be reversed. We developed a novel protocol in rats whereby microspheres injected into the femoral artery allowed a unilateral reduction in functional capillary density in the extensor digitorum longus (EDL), and assessed acute and chronic effects on muscle function.

Simultaneous bilateral EDL force and hindlimb blood flow measurements were made during electrical stimulation. Following functional capillary rarefaction there was an acute microsphere dose-dependent reduction in muscle fatigue resistance, despite preserved femoral artery perfusion. Histological analysis of EDL samples taken from injected animals confirmed a positive correlation between the proportion of functional capillaries and fatigue resistance. Such impaired performance persisted for at least 2 weeks.

Concomitant mechanical overload improved both perfused capillary density and fatigue resistance, confirming that the capacity for muscle remodelling was retained following chronic distributed ischaemia, and that the impact of capillary rarefaction could be alleviated. These results demonstrate that loss of functional capillaries is detrimental to muscle function, even in otherwise healthy tissue, independent of arterial perfusion. Restoration of muscle performance following a mechanical overload stimulus indicates that angiogenic treatments to alleviate microvascular rarefaction may be key to restoring exercise tolerance.

Link: https://doi.org/10.1113/JP278975

In recent years the research and medical communities have lowered the recommended targets for blood pressure control via antihypertensive therapies. Evidence strongly suggests that the chronic raised blood pressure that accompanies aging is one of the more influential downstream consequences of molecular damage and cellular dysfunction that stiffens arteries. Hypertension accelerates the progression of atherosclerosis, damages sensitive tissues of the brain, kidney, and other organs, and promotes detrimental remodeling of the heart. It is a mechanism by which low-level cellular dysfunction is converted into structural damage and systems failure throughout the body. As noted here, controlling blood pressure results in some degree of reduced mortality and raised life expectancy even in the absence of any attempt to address the underlying damage of aging that caused it.

When data from the Systolic Blood Pressure Intervention Trial (SPRINT) were published in 2015, the medical community responded enthusiastically to the news that reducing blood pressure lower than the normal targets could reduce overall death rates by 27 percent for adults at high cardiovascular risk. Investigators now describe how aggressively lowering blood pressure levels can extend a person's life expectancy. They report that having a blood pressure target of less than 120 mm Hg - rather than the standard 140 mm Hg - can add six months to three years to a person's lifetime, depending upon how old they are when they begin intensive blood pressure control.

By applying age-based methods to the data from SPRINT, the team could estimate the long-term benefits of intensive blood pressure control. The SPRINT study enrolled more than 9,000 adults who were 50 years or older, were at high cardiovascular risk but did not have diabetes, and had a systolic blood pressure between 130- and 180-mm Hg (130 mm Hg or higher is considered high blood pressure). Participants were randomized to intensive (at least 120 mm Hg) or standard (at least 140 mm Hg) systolic blood pressure targets. Participants were given antihypertensive therapies, free of cost, to achieve their blood pressure targets and were followed for an average of a little over three years.

Researchers estimated that if people had continued taking their antihypertensive therapies for the remainder of their lives, those with the intensive blood pressure target could add six months to three years to their life expectancy, compared to those with the standard blood pressure target. This span depended upon the person's age - for someone who began antihypertensive medications at 50 years old, they predicted a difference of 2.9 years; for someone 65 years old, a difference of 1.1 years; and for someone 80 years old, a difference of nine months.

Link: https://www.eurekalert.org/pub_releases/2020-02/bawh-ibp022420.php

The research materials here cover the recent work of one of many groups digging deeper in the mechanisms of cellular senescence, in search of novel ways to make senescent cells less harmful to surrounding tissues, or means to selectively destroy them outright. The accumulation of senescent cells with age is now well proven to contribute to aging, generating chronic inflammation and disrupting tissue function via a potent mix of signals known as the senescence-associated secretory phenotype, or SASP. The scientists involved here have discovered that HDAC inhibitors can to some degree suppress the SASP, and this intervention also makes these errant cells function more normally in other respects as well.

It is an open question as to whether making senescent cells act more normally is in fact a sensible goal, versus selective destruction using one of the many senolytic therapies under development. Senescent cells are senescent for a reason: they are damaged in some way, or at the end of their replicative life span. It is plausible to argue that helping senescent cells to survive, even while controlling their bad behavior, will meaningfully increase the risk of cancer due to accumulated mutational damage - protecting cells that really should be destroyed. No-one yet has good data to back one position or another in that argument, but given tools such as HDAC inhibition, and other approaches shown to suppress the SASP to various degrees, that data should emerge in the years ahead.

Interestingly, HDAC inhibitors were already identified as a class of drug capable of modestly slowing aging in short-lived species. The mechanisms of action are still unclear and much debated, however, as HDAC inhibition affects numerous systems in the cell. That it can suppress the SASP makes this a more plausible mechanism for slowed aging, given what is known of cellular senescence in aging, than some of the other possibilities, perhaps.

A deep dive into cellular aging

The number of Americans who are age 65 or older is projected to double to more than 90 million in 2060, translating to nearly 25% of the population, due to the natural aging of the Baby Boomer generation. Today, approximately 80% of older adults have at least two chronic diseases, such as heart disease, cancer, stroke, or diabetes. This trend creates a need to solve the projected onslaught of health problems we face and is fueling scientists to dive into the molecular causes of aging and find medicines that help people live long, healthy lives.

Clusters of chromatin - the mix of DNA and protein normally found in the cell nucleus - leak out to the cytoplasm in senescent cells, triggering inflammatory signals that can promote a number of undesirable health conditions. Researchers set out to find what prompts the formation of chromatin clusters in the first place, embarking on a series of experiments using a human lung cell model of senescence. They found that mitochondria were the culprits driving the formation of pro-inflammatory cytoplastic chromatin and did so through a retrograde communication path to the nucleus.

The scientists also found that an HDAC inhibitor, an FDA-approved drug currently used to treat certain cancers, transformed senescent cells from a large and flat form to a healthier and more visually youthful condition. The HDAC inhibitor-treated cells also had better mitochondrial function, less cytoplasmic chromatin and produced less inflammatory signals. The scientists observed similar beneficial effects when examining the livers of mice in which senescence was induced through radiation or high doses of acetaminophen. However, the side effects of HDAC inhibitors - which include fatigue, nausea and more - make the drugs too toxic for use in preventing disease in healthy individuals.

Mitochondria-to-nucleus retrograde signaling drives formation of cytoplasmic chromatin and inflammation in senescence

Cellular senescence is a potent tumor suppressor mechanism but also contributes to aging and aging-related diseases. Senescence is characterized by a stable cell cycle arrest and a complex proinflammatory secretome, termed the senescence-associated secretory phenotype (SASP). We recently discovered that cytoplasmic chromatin fragments (CCFs), extruded from the nucleus of senescent cells, trigger the SASP through activation of the innate immunity cytosolic DNA sensing cGAS-STING pathway. However, the upstream signaling events that instigate CCF formation remain unknown.

Here, we show that dysfunctional mitochondria, linked to down-regulation of nuclear-encoded mitochondrial oxidative phosphorylation genes, trigger a ROS-JNK retrograde signaling pathway that drives CCF formation and hence the SASP. JNK links to 53BP1, a nuclear protein that negatively regulates DNA double-strand break (DSB) end resection and CCF formation. Importantly, we show that low-dose HDAC inhibitors restore expression of most nuclear-encoded mitochondrial oxidative phosphorylation genes, improve mitochondrial function, and suppress CCFs and the SASP in senescent cells. In mouse models, HDAC inhibitors also suppress oxidative stress, CCF, inflammation, and tissue damage caused by senescence-inducing irradiation and/or acetaminophen-induced mitochondria dysfunction.

Overall, our findings outline an extended mitochondria-to-nucleus retrograde signaling pathway that initiates formation of CCF during senescence and is a potential target for drug-based interventions to inhibit the proaging SASP.

Brain tissue requires a sizable supply of oxygen and nutrients in comparison to most other organs of the body, and is thus disproportionately affected by the age-related decline of the cardiovascular system. This vascular degeneration takes numerous forms: loss of capillary density in tissues; a reduced ability of the heart to pump blood uphill, particularly in heart failure patients; the stiffening and narrowing of major arteries, with consequent hypertension able to cause pressure damage to sensitive tissues; the breakdown of the blood-brain barrier, allowing harmful cells and molecules to leak into the brain. These mechanisms have a meaningful impact on the progression of neurodegenerative conditions such as Alzheimer's disease.

The brain depends on the continuous delivery of oxygen and energy substrates due to its high-energy demand and the lack of long-term energy storage. The cerebral vasculature is well suited for this purpose, where regional cerebral blood flow (rCBF) is tightly regulated and can adapt to match the local energy demands of the nervous tissue. While the topology, anatomy and signalling cascades of the cerebral vasculature is unique to serve its specialized functions, its vascular bed is connected to the general circulation of the body. Thus, any change in blood content (e.g., as part of haemostasis, inflammation or infection) or haemodynamic and biomechanical changes of central blood vessel will affect the cerebral vasculature. Conversely, alterations of the cerebral vessels might have systemic effects. We know that many brain diseases are associated with vascular dysfunctions.

Alzheimer's disease (AD) impairs cognition, memory, and language and causes dementia. AD is defined by deposition of fibrillar amyloid-β (Aβ) plaques and neurofibrillary tangles of hyperphospohorylated tau and neurodegeneration. Accumulating evidence has shown that cerebrovascular disease is a common comorbidity in the presence of AD - and can on its own cause cognitive impairment and dementia (known as vascular dementia) - that contributes additively to its symptomatology and lowers the threshold for the development of dementia. However, given the marked structural changes of the microvasculature, an alternative hypothesis has been proposed stating that vascular dysfunction causes AD-related neuropathology and cognitive impairment (the "vascular hypothesis of AD"). Today, the picture seems more complex and far from complete. It is believed that neuropathological and vascular pathways interact synergistically and feedback to each other to potentiate AD symptoms.

Cerebral vascular abnormalities are highly prevalent in AD patients and can result in cognitive impairment and dementia, and thus can add to the symptomatology caused by AD pathology. However, many vascular processes directly affect and modulate, and often proceed AD neuropathology, the most important one being blood-brain barrier (BBB) impairment and hemodynamic dysfunction. This implicates vascular dysfunction as an integral part of AD etiology and pathophysiology. The interaction is bidirectional, where AD neuropathology can also lead to changes in vascular function. In addition, many changes observed to occur at the cerebral vasculature are related to systemic vascular abnormalities, which occur during aging and can be accelerated and aggravated by cardiovascular diseases. Thus, the cerebral vasculature is the locus where multiple pathogenic processes converge and contribute to cognitive impairment. Strategies that promote vascular health by managing vascular risk factors, changes in life style, and medication can significantly reduce the prevalence of AD, which has been demonstrated in some smaller studies.

Link: https://doi.org/10.1159/000505625

This popular science article is a decent introduction to the still young field of senolytic therapies to selectively destroy senescent cells in aged tissues. That said, the author fails to note any of the numerous senolytic programs other than those of the Mayo Clinic and Unity Biotechnology - which represent an increasingly small portion of the field as a whole. The accumulation of lingering senescent cells is one of the contributing causes of aging; these errant cells secrete a potent mix of signals that spur chronic inflammation, change cellular behavior for the worse, and destructively remodel tissue structure. Senolytic therapies have been demonstrated in mice to turn back the progression of numerous age-related diseases, and results from early human trials have been promising.

Many researchers now view senescence as a beneficial process that evolved as a developmental and cancer prevention mechanism, but one that came with a tradeoff of the damage senescent cells can cause as they accumulate with age. There are still many unanswered questions about how these cells function, but it is already clear to scientists in the field that senescent cells influence a range of age-related pathologies, at least in rodents. Genetic ablation of senescent cells reduces the number of atherosclerotic plaques in mice, improves cartilage development in mouse models of osteoarthritis, boosts bone strength in murine models of osteoporosis, and even staves off neurodegenerative symptoms in models of Alzheimer's disease. These findings have a number of scientists thinking: If clearing senescent cells had such beneficial effects on health, could drugs be developed to do just that?

James Kirkland's group at the Mayo Clinic had started to search for senolytic agents long before the scientific community was convinced of senescent cells' role in aging, but it took him years to work out a good strategy to identify them. In the mid-2000s, his team tried developing toxins or antibodies that target senescent cells, but none of these approaches succeeded in killing senescent cells while sparing non-senescent ones. In 2013, it occurred to Kirkland's team to target the molecular machinery known to be used by senescent cells to defy death. The cells must have those mechanisms in place to avoid undergoing the apoptotic processes that would typically follow exposure to the high levels of harmful proteins they are producing, the team reasoned. Using a bioinformatics approach, the researchers identified several anti-apoptotic pathways that are upregulated in senescent cells, including certain pathways used by malignant B cells to avoid apoptosis and cause lymphoma.

They then screened for approved drugs and natural products that targeted those pathways and thus selectively killed senescent cells. To the group's surprise, two compounds appeared very effective in killing senescent cells in vitro as well as in mice: dasatinib, approved in the US to treat certain leukemias and lymphomas, and quercetin, which is used as a nutritional supplement. "I thought we'd have to screen millions of compounds to get drugs that regulate senescence." But it took fewer than 50 drugs to get the first hits.

Link: https://www.the-scientist.com/features/can-destroying-senescent-cells-treat-age-related-disease--67136

The Methuselah Foundation is one of the oldest of the present generation of organizations focused on advancing human rejuvenation, founded more than 15 years ago. At that time there was none of the present enthusiasm for treating aging as a medical condition, and indeed the concept was mocked outside the scientific community and actively discouraged within research circles by leading scientists in the field of gerontology. The Methuselah Foundation and its network of allies are a large part of the reason why things have changed: it took a great deal of work to change this dismissive culture into one that saw and embraced the potential of rejuvenation biotechnology.

Now that there is, finally, a nascent industry focused on the treatment of aging, the Methuselah Foundation has become more involved in funding companies and promoting their efforts via the Methuselah Fund. At the present time, this is one of the best uses for philanthropic funding - to help seed a much greater flow of capital into the longevity industry, to enable the first companies to thrive and demonstrate the efficacy of their approaches. (The other best use being, of course, to push forward the numerous promising rejuvenation research projects that continue to languish in academia for lack of attention). The latest update from the Methuselah Foundation, arriving in my in-box a few days ago, covers some of the highlights from Methuselah Fund portfolio companies.

Methuselah Fund has found success by investing in the longevity field when almost no one else was willing to take the risk. The M Fund has proved to be an invaluable resource in our efforts to put mission first and money second. M Fund continues to perform well and plans for a second Fund are currently underway. The Methuselah Fund hopes to continue to guide investments into the winners of the longevity field for many years to come.

New Parts for People: Volumetric

Incubated by the Methuselah Foundation, Volumetric was featured on the cover of Science Magazine in May 2019 due to their technological breakthrough. Their proprietary light-based 3D bio-printers and bio-inks represent a 10x leap in speed and 5x leap in resolution compared to legacy bio-printing methods, making them a leading competitor for the NASA Tissue Engineering Prize. In September 2019, the Vascular Tissue Challenge, managed by the Methuselah Foundation for NASA, entered its final phase of the project. By the end of September 2019, a total of 21 teams successfully completed their trial applications after the last Vascular Tissue Challenge Summit hosted at NASA Ames Research Center. Three teams have been approved to move into the final Trial Phase of the Challenge. Another five teams are in a second round of review with the judging committee and are nearing approval of their trials. We are looking forward to an exciting year with upcoming Vascular Tissue Challenge trials taking place to mark a renaissance in bioengineering of thick tissues.

Curing Alzheimer's disease: Leucadia Study Results

Leucadia Therapeutics discovered a major trigger for Alzheimer's disease pathology and has developed a patented strategy to correct that condition. Leucadia's patented Arethusta technology restores cerebrospinal fluid flow across the cribriform plate, improving the clearance of toxic metabolites from the earliest regions of the brain to be affected by Alzheimer's disease. Leucadia will soon pursue FDA approval for clinical trials. Before that, however, they will finish a 2,000-person cribriform plate imaging study called Project Cribrose by mid-2020. One exciting and more immediate development is that Leucadia has created a diagnostic algorithm using sophisticated machine learning technology. Project Cribrose will optimize and enhance this algorithm so that Leucadia can start providing a diagnostics tool to find out a patient's likelihood of developing Alzheimer's.

Anti-aging Drugs: Oisín Bio Human Trial

Oisín is pursuing a scientifically sound, targeted approach that may have the potential to address the biological underpinnings of some of society's most devastating age-related diseases by addressing the damage created by the aging process itself. In preclinical studies, the company's investigational therapeutics have significantly reduced senescent cell burden in naturally aged mice and extended median lifespan by more than 20% even when the treatment was started in old age. The company has advanced studies in non-human primates and has spun out another company, OncoSenX to prove the platform and technology in one indication, cancer. This company was formed with an original grant from the Methuselah Foundation to use Oisín Bio's technology to target prostate cancer. The project was a success and the company is targeting starting phase 1 trials in Canada this year.

Reversing Aging by Reprogramming Cells: Turn Bio

Turn Bio has developed a technology capable of safely reprogramming how DNA functions epigenetically, which is paving the way to a potentially translatable strategy for in-vivo and ex-vivo cell rejuvenation treatments. They are also developing interventions that are focused on treating skin rejuvenation, osteoarthritis, and muscular diseases. Turn Bio has successfully achieved in situ delivery in multiple tissues, such as in muscles, eyes, and brain. They are also in the process of testing systemic delivery. Currently, their most promising approach is based on nanotechnology developed to deliver a mRNA cocktail to tissues - accurately and without invoking an adverse immune response.

Accelerating Drug Discovery: Viscient

Founded and staffed by a team composed of former Organovo and Ardea Biosciences scientists and entrepreneurs, Viscient is driving a revolution in drug discovery, overthrowing the old paradigm of discovery in animal models. It is our conviction that the age of using mice as the primary research model for biotech is rapidly passing, to be replaced by tissue engineered organoids. Methuselah's goal in investing in Viscient is to drive the actual use of human 3D printed tissue models, and through their demonstrated vast superiority to animal models, lead in reorienting the industry and the regulators away from animal testing and to more efficient, effective, and relevant models of disease.

Calorie restriction, eating up to 40% fewer calories while maintaining optimal micronutrient intake, near universally improves health and extends life across species assessed to date. Flies are a noteworthy exception to the reliability of this effect; the evidence is decidedly mixed for intermittent fasting and calorie restriction to work in flies in the same way that it does in nematodes, mice, and other laboratory species. Where it does work, it might not be working for the same reasons as it does in other species. The results here are somewhat characteristic of examinations of dietary restriction in flies, finding another way in which their response differs from that of, say, mice.

Dietary restriction (DR) extends health and life span across taxa, from baker's yeast to mice, with very few exceptions. The reduction in total calories - or restriction of macronutrients, such as protein - extends life span reliably. Although the precise universal mechanisms that connect DR to ageing remain elusive, translation of DR's health benefits to human medicine is deemed possible. The widespread assumption of DR's translational potential originates from the notion that DR's beneficial effects are facilitated by shared evolutionary conserved mechanisms, as beneficial effects of DR are observed across taxa. Experiments on our close evolutionary relatives, rhesus monkeys (Macaca mulatta), have demonstrated that DR could be translational. Still, the mechanisms by which these benefits are accrued physiologically may differ between species, as no single genetic or pharmaceutical manipulation mimicking the benefits of DR across model organisms exists.

Shared universal mechanisms can only be inferred from the ubiquity of the DR longevity response in the animal kingdom, when the selection pressures responsible for such evolutionary conservation are understood. The DR response itself may have evolved once, and mechanisms might be conserved. Alternatively, DR could have undergone convergent evolution, either using similar mechanisms - or by adopting alternative ones. Only if the DR response is rooted in ancient physiology (i.e., evolved once or through convergent evolution) can possible translation of mechanistic research on model organisms be confidently inferred.

Guided by the conviction that DR evolved as an adaptive, pro-longevity physiological response to food scarcity, biomedical science has interpreted DR as an activator of pro-longevity molecular pathways. Current evolutionary theory predicts that organisms invest in their somatic tissues during DR, and thus, when resource availability improves, should outcompete rich-fed controls in survival and/or reproduction. Testing this prediction in Drosophila melanogaster (more than 66,000 individuals across 11 genotypes), our experiments revealed substantial, unexpected mortality costs when flies returned to a rich diet following DR. The physiological effects of DR should therefore not be interpreted as intrinsically pro-longevity, acting via somatic maintenance. We suggest DR could alternatively be considered an escape from costs incurred under nutrient-rich conditions, in addition to costs associated with DR.

Link: https://doi.org/10.1126/sciadv.aay3047

Miniaturizing bioprinters to allow finely controlled printing directly onto (or into) the body is an important logistical advance in this part of the tissue engineering field. It allows for a much more efficient approach to building up new tissue where needed, such as injured skin. Researchers here demonstrate that their implementation of a handheld skin printer accelerates regeneration of severe burn injuries in animal models, suggesting they are a fair way along the road to having something that can be converted into a viable product for widespread use.

A new handheld 3D printer can deposit sheets of skin to cover large burn wounds - and its "bio ink" can accelerate the healing process. The device covers wounds with a uniform sheet of biomaterial, stripe by stripe. The bio ink dispensed by the roller is composed of mesenchymal stromal cells (MSCs) - stem cells that differentiate into specialized cell types depending on their environment. In this case, the MSC material promotes skin regeneration and reduces scarring. The team unveiled the first prototype of the skin printer in 2018. The device was believed to be the first device of its kind to form tissue in situ, depositing and setting in place in two minutes or less. "Previously, we proved that we could deposit cells onto a burn, but there wasn't any proof that there were any wound-healing benefits - now we've demonstrated that."

The current method of care for burns is autologous skin grafting, which requires transplantation of healthy skin from other parts of the body onto the wound. But large, full-body burns pose a greater challenge. Full-thickness burns are characterized by the destruction of both the outermost and innermost layers of the skin; these burns often cover a significant portion of the body.

Since 2018, the printer has gone through 10 redesigns, as the team moves towards a design they envision surgeons using in an operating room. The current prototype includes a single-use microfluidic printhead to ensure sterilization, and a soft wheel that follows the track of the printhead, allowing for better control for wider wounds. The researchers believe that the handheld skin printer could be seen in a clinical setting within the next five years. "Once it's used in an operating room, I think this printer will be a game changer in saving lives. With a device like this, it could change the entirety of how we practice burn and trauma care."

Link: https://news.engineering.utoronto.ca/handheld-3d-skin-printer-demonstrates-accelerated-healing-of-large-severe-burns/