Rejuvenating Aging Stem Cells ... Or Not

You might recall work published last year that suggested aging, non-responsive stem cells responsible for muscle maintenance and repair could be brought back into operation by suitable biochemical cues. Here is another relevant study:

Satellite-cell pool size does matter: Defining the myogenic potency of aging skeletal muscle

The deteriorating in vivo environment is thought to play a major role in reduced stem cell function with age. The capacity of stem cells to support tissue maintenance depends not only on their response to cues from the surrounding niche, but also on their abundance. Here, we investigate satellite cell (myogenic stem cell) pool size and its potential to participate in muscle maintenance through old age. The numbers and performance of mouse satellite cells have been analyzed using molecular markers that exclusively characterize quiescent satellite cells and their progeny as they transit through proliferation, differentiation and generation of reserve cells. The study establishes that abundance of resident satellite cells declines with age in myofibers from both fast- and slow-twitch muscles. Nevertheless, the inherent myogenic potential of satellite cells does not diminish with age. Furthermore, the aging satellite cell niche retains the capacity to support effective myogenesis upon enrichment of the mitogenic milieu with FGF. Altogether, satellite cell abundance, but not myogenic potential, deteriorates with age. This study suggests that the population of satellite cells that participate in myofiber maintenance during routine muscle utilization is not fully replenished throughout life.

Stem cell research is very much a field of change, like everything touched by modern biotechnology. The influx of new information is rapid indeed, which should mean that any debate that can be solved by learning more will be short and sweet. Can we rejuvenate aging stem cells, or do we just need to replace them? Or both? At the present rate, we'll probably know the detailed answer to that question by the end of 2007 - and possibly the answer to "how do we do it?" as well.

It is interesting to speculate on the sort of cell therapies that will be developed to repair the damage that aging inflicts upon us - intermediary therapies, really, that will be developed and used prior to technologies capable of preventing this damage from occurring, or repairing it in situ as it happens. It is not unreasonable to look at the state of stem cell science, bioinformatics and gene therapy today and predict that medical researchers of 2020 will be culturing new stem cell populations for individuals, correcting age-related damage to genetic and cellular material before returning the new cells to the body.

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