Aging Stem Cells and DNA Damage

It's comparatively easy to produce results that look like premature aging - anything that raises the rate of biochemical damage to your cells should do the job. Diabetes has been used as a model for aging in animal studies for some time, for example. Deliberate changes leading to what appears to be premature aging are not always relevant to "normal" aging. From EurekAlert!: "Normally, a few stem cells are enough to completely replenish the bone marrow of mice and produce normal amounts of blood and immune cells. However, error-filled blood-forming stem cells taken from the mutant mice were much less effective at colonizing the depleted bone marrow than normal stem cells, and became even less effective when taken from older mutant mice. ... these results suggest that mutations accumulating in stem cells as they age were preventing them from doing their normal job of producing new blood and immune system cells. ... young stem cells from normal mice contained [little] or no DNA damage. Older stem cells, on the other hand, showed extensive [DNA damage]. ... blood-forming stem cells do accumulate DNA damage with age even though they rarely divide, and that damage is passed on to the blood and immune system cells they make. Weissman said these findings could explain the origin of blood cancer (leukemia) and immune dysfunctions that occur as people age."



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