Energy Producing Metabolic Pathways in Functional Regulation of the Hematopoietic Stem Cells.

The hematopoietic system has a very well-studied hierarchy with the long-term (LT) hematopoietic stem cells (HSCs) taking the top position. The pool of quiescent adult LT-HSCs generated during the fetal and early postnatal life acts as a reservoir to supply all the blood cells. Therefore, the maintenance of this stem cell pool is pivotal to maintaining homeostasis in hematopoietic system. It has long been known that external cues, along with the internal genetic factors influence the status of HSCs in the bone marrow (BM). Hypoxia is one such factor that regulates the vascular as well as hematopoietic ontogeny from a very early time point in development. The metabolic outcomes of a hypoxic microenvironment play important roles in functional regulation of HSCs, especially in case of adult BM HSCs. Anaerobic metabolic pathways therefore perform prominent role in meeting energy demands. Increased oxidative pathways on the other hand result in loss of stemness. Recent studies have attributed the functional differences in HSCs across different life stages to their metabolic phenotypes regulated by respective niches. Indicating thus, that various energy production pathways could play distinct role in regulating HSC function at different developmental/physiological states. Here, we review the current status of our understanding over the role that energy production pathways play in regulating HSC stemness.