Abstract
Ageing is a biological certainty for all living organisms, and is due to the loss of tissue homeostasis and regenerative capacity (except for newts) in which somatic stem cells are thought to play an important role. Many ageing-associated dysfunctions in stem cells have been described, but it remains ambiguous whether these are merely an outcome of ageing or are causal. Parabiotic animal studies suggest there are factors in the systemic environment that can influence the regenerative capacity of tissues. These factors can be altered by ageing, but it is not clear where these age-dependent factors are derived. A recent provocative study on muscle stem cells, in a mouse model of human progeria, proposes a mechanism that might provide answers to these fundamental ageing questions.