Throughout one’s life, the blood is constantly being replenished from blood stem cells. However, these cells lose their functionality in old age. Researchers at the Leibniz Institute on Aging – Fritz Lipmann Institute (FLI) have now found a gene mechanism that is responsible for the aging of hematopoietic stem cells. The gene Igf2bp2 is important in youth for the full function of these cells, as it activates their growth and metabolism. When the gene is missing, however, the aging-associated loss of function of the stem cells is surprisingly diminished. The eventual aging of hematopoietic stem cells is apparently already preprogrammed by their gene-driven growth in youth.