Researchers have worked out why cells that stop dividing often release inflammatory signals that are linked to various age-related disorders.

Cells enter this 'senescent' state as tissues age, but it is not clear why they secrete numerous molecules, some of which cause inflammation. Judith Campisi at the Buck Institute for Research on Aging in Novato, California, and her team developed a mouse model in which they could isolate and study senescent cells. They found that blood-vessel and skin cells enter a senescent state at the site of a skin injury, where they promote healing by secreting a growth factor.

This could explain why senescent cells evolved the ability to secrete molecules, the team says.

Dev. Cell 31, 722–733 (2014)