Oxygen Availability and Self Renewal of Stem Cells

The relationship between stem cells and micro-environmental/culture oxygenation has been reviewed. The basic principle of stem cell biology, ldquothe generation-age hypothesisrdquo, and hypoxic metabolic properties of stem cells are considered in the context of the oxygen-dependent evolution of life and its transposition to ontogenesis and development. A hypothesis relating the self-renewal with the anaerobic and hypoxic metabolic properties of stem cells and the actual O₂ availability is elaborated (ldquooxygen stem cell paradigmrdquo). The revision of our knowledge on cell/cytokine physiology, which has been acquired ex-vivo at non physiological atmospheric (20-21%) O₂ concentrations representing a hyperoxic state for most primate cells, has thus become imperious for an adequate approach to cell engineering.