Mechanisms of Stem Cell Ageing

Epigenetic regulation of aging stem cells

“…In humans, age-dependent changes in hematopoietic stem and progenitor cell number also differ depending on the study. Early reports examining changes to whole bone marrow (Ogawa et al, 2000) or a heterogeneous CD34 þ cell population (Waterstrat et al, 2008) indicated a decrease in progenitor cell frequency. However, the most recent studies of more pure cell fractions report higher numbers of primitive stem and progenitor cells with age (Taraldsrud et al, 2009;Beerman et al, 2010b).…”

Cell intrinsic and extrinsic mechanisms of stem cell aging depend on telomere status

“…(Morrison et al, 1996;Sudo et al, 2000;Rossi et al, 2005;Waterstrat et al, 2008). Cell intrinsic: genetic factors modify HSC self renewal (Yang et al 2007).…”

“…Moreover, C57BL/6J mice rarely develop hematopoietic failure during aging. This scenario appears to be very different from human aging, which is characterized by a decline in HSC number (Waterstrat et al,2008), and frequent occurrence of bone marrow failure and anemia (Beghe et al, 2004). It appears likely that shorter telomeres and longer lifespan in humans represent fundamental differences affecting stem cell aging in humans but not in C57BL/6J mice.…”

“…In some wild type mouse strains (e.g., C57Bl/6J) the number of HSCs increases during aging, whereas other mouse strains, such as DAB2 and BalbC, show a decrease in HSC number during aging (Morrison et al, 1996, Waterstrat et al, 2008. Interestingly, the number of HSCs has been associated with murine lifespan (Henckaerts et al, 2004;Van Zant et al, 1990).…”

Aging stem cells, latexin, and longevity

“…The amount of active bone marrow in humans progressively diminishes from childhood to old age, during which time active marrow is restricted to the pelvis, sternum, and vertebrae, and where even in these sites the marrow cellularity is reduced [27]. Moreover, the number of CD34+ cells in the marrow and blood of the very old, including centenarians, is greatly reduced [28,29]. Despite these quantitative changes there is little solid evidence that longevity is threatened by a lack of stem cells [30].…”