Figure 2. Senescence and consequences for tissue homeostasis.

Senescence can have beneficial effects when acute because it allows the tissue to adapt to stress. Senescent cells secrete proinflammatory molecules in order to recruit immune cells that can then lead to clearance of senescent cells in the damaged tissue. If the regenerative capacity is efficient, tissue homeostasis is maintained. Senescence is a tumor suppressor mechanism and has some beneficial effects during wound healing and fibrosis. Aging induces a decrease in the efficiency of this cycle of senescence/recruitment/clearance/regeneration. Senescence can have deleterious effects when chronic, worsening pathologies such as type 2 diabetes and atherosclerosis.