Fight Aging!

For much of this year the Bristlecone, the Methuselah Foundation's blog, has published a series of interviews with researchers of note in the field of tissue engineering. They have been quite education, often covering some of the important infrastructural aspects of the research and development process that gain little attention elsewhere. The Foundation has a strong interest in advancing this arm of medicine, and does so through strategic early stage investments, such as in bioprinter startup Organovo, as well as through initiatives such as the New Organ research prize series. This month the Bristlecone published a lengthy three part interview with David Williams of the Tissue Engineering and Regenerative Medicine International Society (TERMIS). Some interesting opinions can be found therein, and you should certainly read the whole thing as there is much more there than is quoted below:

Biomaterials and Clinical Translation

I published a short paper recently called "The Biomaterials Conundrum in Tissue Engineering," and to put it simply, I think we've mostly gotten it wrong. I'm not being too critical, because it was probably inevitable, but the early attempts at tissue engineering involved material scaffolds, and that's where biomaterials come in. The scaffold is the form in which you're going to develop an engineered organ, and the originators felt that they needed to get FDA approval for them. Therefore, they needed to use an FDA approved material, and although this was understandable, I think it was misguided.

The sole criteria for FDA approval for biomaterials used in implantable devices was that the material did no harm. It had to be known to be safe. You're never going to get a scaffold or template material to function properly if all it does is play safe. You need the material to actually stimulate cells through mechanical forces or growth factor delivery, and standard synthetic polymers were never going to do this reliably and routinely. Because of this, I think we need totally different types of materials that try to replicate or represent the micro-environment of the cell. I've been shouting this from the rooftops for a long time now. It can't be an engineered fabricated structure that looks nothing like the cell micro-environment, or we'll never be able to make the cell regenerate the tissues that we want.

We do have a number of pretty good hydrogels that do this, especially biologically-based hydrogels. That's why decellularized extracellular matrix (ECM) is getting so popular. I don't think we're there yet by any means, but there are some interesting approaches around. But the key is that we have to have a different mindset regarding how we develop our biomaterials, and the regulators have to have a different mindset regarding how they regulate them. We can't use the standard tests for safety that the FDA is saying that we still have to use, and that's a big issue at the moment. For the most part, the regulators still want to play it too safe.

Core Principles and Challenges

Bear in mind that what we're trying to do is to take a group of cells and persuade them to do something they don't want to do. That is, to express new extracellular matrix that can then be organized into the structure and function of an organ. I think many of the different scientific principles are in place. We've made big progress already, and to me, the key issue is in putting everything together such that we can develop the structures that function as organs do. We know how to do the little bits, but we still have to explore the complex functioning of the whole.

[Vascularization] is still one of the most important issues. There has been a fair bit of progress made in vascularization, especially in using some small molecules and certain growth factors to encourage newer vascularization. So there are encouraging signs in this area, but it does remain one of the bigger challenges. Take muscle tissue engineering, for example. It's already possible to regenerate small amounts of muscle, but the integration of that into a functional muscle regenerative project is much, much harder. We need to address the integration issues more than anything, and we need to start doing it for the areas where our current therapies are weakest. We had to start somewhere, and so skin, cartilage, and bone were good starting points. In most all of these areas, we've now had some degree of clinical success in alternative treatment modalities. Where we don't have good therapies at the moment is in areas like degenerative disease, especially neurodegeneration and musculo-skeletal regeneration, and I'd like to see more effort being addressed in those areas.

The International Front

It's pretty clear that the United States, and a few countries in Europe, and one or two elsewhere, are at the forefront of developments in these medical technologies in regenerative medicine. But they can't do everything. We have to recognize that there are very good academic, clinical, and commercial entities all around the world. And I think it is appropriate that we interact with them in order to get the best of everything.

Also, when you look at issues of commercialization and clinical translation, we know that here in the U.S., there are - sometimes understandably - many limitations and barriers to how far and how fast we can go. And there are opportunities in other parts of the world where there are different formats and different styles. Part of my rationale is to try to get the best of all possible commercial, clinical, and academic opportunities in different parts of the world.