Role of hypoxia in stem cell development and functioning.

The response of stem cells (SC) to hypoxia is one of the main mechanisms of an organism's adaptation to changing terms of external and internal environment. This review describes the role of hypoxia in functioning of various stem cell, types--embryonic, hematopoietic, nmesenchvmal and neural, paying special attention to the very limited data concerning intermittent hypoxia (IH) effects. All stem cells and their precursors exist in microenvironment named stem cell niches. The most crucial factor for their normal functioning is hypoxia. which contributes to maintaining the SC in quiescent state with necessary rate of self-renewal. The key element qf these mechanisms is a complex of hypoxia-inducible transcription factors. An additional exogenous hypoxic impact leads to activation of SC system. Very scant information on IH effects on SC that was obtained generally in cell culture models, reveals that intermittent hypoxia at certain duration and intensity is a more potent trigger of transcription activation than constant hypoxia. In the future a method of IH training/treatment could be effectively used for correction of physiological changes and pathological disorders in art organism.