Stem cells and aging

Abstract

The prevailing view of the aging process is that it reflects the integrated sequelae of accumulated random biological damage. These sequelae have been referred to as the hallmarks of aging and one of these hallmarks is the age-related decline in somatic stem cell functions; termed stem cell exhaustion. This stem cell exhaustion construct implies that stem cell aging across different tissues should have a number of similar characteristics. However, such is not the case. The characteristics of aging for stem cell populations in a variety of tissues, (hair follicle, skeletal muscle, hematopoietic tissue, skin, intestine and testes), display many distinctive tissue specific features. This observation implies that stem cell exhaustion is not a generic process consequent to the accumulation of random biological damage but rather represents the manifestation of tissue specific evolved programs.