Rejuvenating Stem Cells Slow Muscle Degradation
Aging athletes know that regardless of your workout regiment, you can't stop the rising tide of muscle degradation. However, a pair of recent studies published in Nature Medicine has discovered that this degradation is, at least in part, caused by a functional decline in muscle stem cells. The researchers argue that these cells can be rejuvenated, potentially providing a new therapy to 'stem the tide' of muscle degradation in the elderly.
In both studies, which were conducted independently but approached in the same manner, researchers took both young and aging mice and compared muscle-cell composition and muscle strength. The research teams quickly identified a common defect in the degrading muscles of the aging mice. The adult stem cells of those muscles, normally thought to maintain efficiency even in old-age, showed an increasingly reduced capacity to repair muscle fibers and produce new cells.
Adult stem cells, unlike their controversial embryonic 'cousins,' do not have the potential to become any cell required. What they can do however, is endlessly reproduce the cells needed for the organ they are located in. For instance, the adult stem cells located in the cellular makeup of the human heart can produce healthy new copies of the cells that form heart tissue.
For decades, scientists have thought that the reproduction rate of adult stem cells never changes. They maintained that muscle degradation occurs when the rate at which muscle cells die begins to outweigh the rate at which new cells are produced. This occurs when the average lifespan of a cell in an aging body begins to shorten due to the numerous complications of aging.
However, these new studies have both found that, at least in the muscles of mice, the cell-production rates of adult stem cells decline with age as well, significantly contributing the rate of muscle degradation in the elderly.
The good news is that both teams of researchers also found that this inhibition of the adult stem cells seems to have been caused in the mice by a sudden increase in dysfunctional activity in the cells. Knowing this, the researchers conclude that therapeutic treatments can be designed to correct this problem, essentially rejuvenating the cells, and thus the muscle -- stemming the tide of muscle degradation.
Both studies were published in Nature Medicine on February 16. Abstract links can be found below.
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