Fight Aging!

Cancer, stroke, and other injuries to the brain have provided some insight into how the brain can restructure in response to damage. Provided that the damage progresses relatively slowly, as in the case of brain cancers, areas of the brain such as the neocortex can create new functional networks in order to maintain capabilities. When damage is fast, as in stroke, capabilities are lost. A few researchers see this as proof that it should be possible in principle to slowly and incrementally replace aged and damaged brain tissue with youthful tissue, given sufficiently advanced tissue engineering technology.

The focus of Jean Hébert's scientific work is the neocortex, the outer part of the brain that looks like a pile of extra-thick noodles and which houses most of our senses, reasoning, and memory. The neocortex is "arguably the most important part of who we are as individuals, as well as maybe the most complex structure in the world." There are two reasons Hébert believes the neocortex could be replaced, albeit only slowly. The first is evidence from rare cases of benign brain tumors, like a man described in the medical literature who developed a growth the size of an orange. Yet because it grew very slowly, the man's brain was able to adjust, shifting memories elsewhere, and his behavior and speech never seemed to change - even when the tumor was removed. That's proof, Hébert thinks, that replacing the neocortex little by little could be achieved "without losing the information encoded in it" such as a person's self-identity.

The second source of hope, he says, is experiments showing that fetal-stage cells can survive, and even function, when transplanted into the brains of adults. For instance, medical tests underway are showing that young neurons can integrate into the brains of people who have epilepsy and stop their seizures. "It was these two things together - the plastic nature of brains and the ability to add new tissue - that, to me, were like, 'Ah, now there has got to be a way.'"

One challenge ahead is how to manufacture the replacement brain bits, or what Hébert has called "facsimiles" of neocortical tissue. During a visit to his lab Hébert described plans to manually assemble chunks of youthful brain tissue using stem cells. These parts, he says, would not be fully developed, but instead be similar to what's found in a still-developing fetal brain. That way, upon transplant, they'd be able to finish maturing, integrate into your brain, and be "ready to absorb and learn your information." To design the youthful bits of neocortex, Hébert has been studying brains of aborted human fetuses 5 to 8 weeks of age. He's been measuring what cells are present, and in what numbers and locations, to try to guide the manufacture of similar structures in the lab.

Hébert's ideas appear to have gotten a huge endorsement from the US government. Hébert has proposed a $110 million project to ARPA-H to prove his ideas in monkeys and other animals, and that the government "didn't blink" at the figure. ARPA-H confirmed this week that it had hired Hébert as a program manager.

Link: https://www.technologyreview.com/2024/08/16/1096808/arpa-h-jean-hebert-wants-to-replace-your-brain/