Accumulation of lingering senescent cells is one of the causes of aging; these cells secrete a potent mix of molecules that produce inflammation, disrupt tissue structure and function, and alter the behavior of other cells for the worse. This signaling is useful during wound healing, where senescent cells are created and then destroyed once they have served their purpose, but like most such processes it becomes quite harmful when sustained over the long term. Researchers are presently hotly engaged in developing senolytic therapeutics to destroy senescent cells, and thereby achieve a narrow form of rejuvenation.
Prior to the present focus on senescent cells in aging, most work on cellular senescence was carried out in the context of cancer research. Senescent cells have quite the interesting relationship with cancer. While the state of senescence is an anti-cancer mechanism, shutting down replication in cells that are damaged and may become cancerous, the presence of too many senescent cells makes the tissue environment more hospitable to cancer, more amenable to cancer growth and survival. Along with the age-related decline of the immune system, this is one of the reasons why cancer is an age-related condition.
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