Читать книгу Pathy's Principles and Practice of Geriatric Medicine - Группа авторов - Страница 47

Stem cells are present in all tissues and organs after development and regenerate damaged tissues throughout life. The repair and regenerative potential of many tissues declines with ageing due to functional attrition in several stem cell compartments (e.g. hematopoietic, neural, mesenchymal, and intestinal epithelial stem cells, as well as satellite cells in muscles).⁵⁹ Stem cell exhaustion is seen as an integrative consequence of several components of biological ageing discussed in this chapter, including DNA damage, epigenetic alterations, telomere shortening, cellular senescence, and mitochondrial dysfunction.¹⁵ Hematopoietic stem cells are probably the most‐studied (partly because they are more easily available), and stem cell exhaustion is thought to be a major driver of immunosenescence (see the next section).

As mentioned earlier, reduced regeneration of tissues by progenitor cells may theoretically contribute to tissue dysfunction and, thus, to the ageing process. However, stem cell exhaustion is difficult to measure before the onset of its clinical consequences, and evidence is scarce for a contribution of this phenomenon to ageing. It is worth mentioning that transplantation of muscle‐derived stem cells from young mice extends the health‐ and lifespan of progeroid mice, even in tissues with undetectable donor cells, suggesting that they may be beneficial through secreted factors.⁶⁰