How old can we get? Does our cells know that?
When it comes to aging, certain tissue types seem to lead the charge, according to Professor of Stem Cell and Regenerative Biology Lee Rubin, who directs the Harvard Stem Cell Institute’s Therapeutic Screening Center. Particular tissues — nerve cells appear to be one — somehow signal to others that it’s time to age. This raises the prospect, Rubin said, that aging might be reversed by treating these key tissue categories, rather than designing individual treatments for the myriad tissue types that make up the body.
In addition to key tissues, certain chemical pathways — like insulin signaling —seem to be able to control aging, said Rubin, whose work has received backing from the National Institute of Neurological Disorders and Stroke, as well as private foundations. The insulin signaling pathway is a chemical chain reaction in which the hormone insulin helps the body metabolize glucose. Reducing it has been shown to greatly extend life span in flies and worms, Rubin said. Also, signaling doesn’t have to be reduced in all tissues.
Researchers have identified but not yet confirmed candidate blood factors for the rejuvenating effects. What seems not in doubt is the overall effect of the young blood on the old mouse. Interest is intense enough that a California company, Alkahest, has begun experiments giving Alzheimer’s patients plasma from young blood in hopes of improving cognition and brain function.
Even if that approach works, Rubin said, there would be practical hurdles to the widespread administration of young people’s blood plasma to older patients. But with an active compound identified, a drug could be made available to restore at least some cognitive function in Alzheimer’s patients.
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