Cell-centric hypotheses of aging.

Aging in mammals results in numerous age related pathologies such as diabetes, and Alzheimer's disease which ultimately lead to organ failure and the demise of the organism. Numerous cell-centric hypotheses have attributed the disorders of aging to lie downstream to age dependent cellular damage to biologic signaling pathways, bio-informational molecules, telomeres, organelles, and stem cells. Here, we review these cell-centric causes of aging that range from the disposable soma theory, to somatic mutation theory, and free radical theory, to theories that ascribe aging to DNA damage and methylation (DNAaging and DNA superaging), impairment of autophagy (GarbAging), telomeric attrition, senescence, immunoscencence and inflammaging. Others view that aging is caused by MitoAging, NutrimiRaging and miRagings to exhaustion of stem cell pool. Together, the current models of aging, show the existence of damage to different cellular compartments. However, it is not yet clear which, if any, of these cellular damages represent the most proximal cause of aging.