Definition
Cellular senescence is a durable arrest of cell division triggered by stresses such as telomere shortening, DNA damage, oncogene activation and oxidative stress. Leonard Hayflick described the limited replicative capacity of cultured human cells in 1961. Senescent cells resist apoptosis, enlarge, and show markers such as senescence-associated β-galactosidase activity and elevated p16INK4a and p21. Many secrete inflammatory cytokines, proteases and growth factors, collectively the senescence-associated secretory phenotype. Senescence suppresses tumour formation and contributes to wound healing, yet the accumulation of senescent cells with age is associated with tissue dysfunction in animal models. Selective removal of these cells is the goal of senolytic research.