Written in bone: young bone makes young blood

Ageing of bone marrow haematopoietic stem cells has been mostly associated with cell-intrinsic mechanisms. New findings published in The EMBO Journal now show that reduced levels of the secreted matrix protein osteopontin in old bone marrow stroma cause ageing-associated features in HSCs. In line, old HSCs are functionally rejuvenated by interaction with protease-cleaved osteopontin fragment, and perform like young blood stem cells in vivo.