Haematopoietic stem cell ageing

The question of whether haematopoietic stem cells age has raised considerable controversy, and has been re-opened recently, as a result of the growing interest in stem cells for transplantation and gene therapy. Studies have focused on the generation of different blood cell elements and the capacity for self-renewal; properties that characterize stem cells. Taken together, it appears that basal haematopoiesis is maintained throughout life, yet, the capacity to cope with haematological stress is decreased in advanced age. In principle, stem cells derived from aged donors can be used for autologous transplantation, when needed to recover basic haematopoiesis. However, patterns of T cell development are altered in ageing, and intervention to augment T cell response still needs to be considered. Current methods for expansion and maintenance of stem cells in vitro enable examination of stem cell potential for long-term expansion and function. A critical evaluation of the possible risks of replicative senescence and developmental changes in stem cells has become feasible. Ageing effects may relate to cell replication, cell migration and lymphoid differentiation. Understanding of the mechanisms underlying these processes will enable the fidelity of stem cell expansion and maintenance of their potential for long-term function.