The objectives of this review were first to critically review what is known about the effects of
aging on stem cells in general, and hematopoietic stem cells in particular. Secondly,
evidence is marshaled in support of the hypothesis that aging stem cells play a critical role in
determining the effects of aging on organ function, and ultimately on the lifespan of a
mammal. Aging has both quantitative and qualitative effects on stem cells. On balance, the
qualitative changes are the more important since they affect the self-renewal potential …