Cellular senescence is one of the root causes of aging. Cells enter a senescent state in response to damage or the end of their replicative life span, and near all quickly self-destruct or are destroyed by the immune system. Others enter senescence to assist in regenerative processes following wounding, again being destroyed soon afterwards. Senescent cells that linger are a real problem, however. They generate harmful signaling that produces chronic inflammation, destructively remodels tissue structures, and changes the behavior of nearby cells for the worse. The accumulation of senescent cells over the years directly contributes to the progression of age-related dysfunction, disease, and risk of death.
Just how many senescent cells is any given individual burdened with, however? What should we expect from this cause of aging at a specific age? Is it negligible at 40 or 50, with a sudden leap to significant levels at 60? Does the answer vary by tissue type? How do the usual health-associated lifestyle choices affect these numbers? Are senescent cells significantly different from tissue to tissue in terms of the signals they generate and the harm done?
The answers to these questions
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