•Proliferation and
differentiation of Type A, B, and C stem and progenitor cells decreases with aging. This appears to be associated with buildup of NF-kappaB and P16/Ink4a.
•Although the mobilization
responsiveness of Type C stem cells declines
with age, it appears that their regenerative capability can to some extent be restored through environmental messages
or induction of Notch activity.
• The gene expression profiles in Type A human
embryonic stem cells offer
regenerative anti-aging potential not found in more mature stem cells.
•This matter of concern
here is that advanced aging is due to a slowing rate of organ regeneration due to declining
SSC differentiation
activity, this in turn being due to exhaustion of pools of Type B and Type C stem cells because of differentiation and replicative senescence.