Kinetics of hemopoietic stem cells in a hypoxic culture.

The influence of low oxygen tension on the clonal growth of hemopoietic stem cells in vitro was examined. The numbers of colonies of neutrophil, macrophage, and eosinophil progenitors (CFU-C), derived from human bone marrow, increased at a rate 1.7 times higher in low oxygen tension (7% O2) than in a gas phase that contained air (19% O2). The erythroid (BFU-E) and multipotential (CFU-mix) progenitors increased about 2.4 times in 7% O2, and the increase in the composed cell type of mixed colonies showed no rate difference in either gas phase. Under atmospheric conditions, a mouse mast cell progenitor (CFU-mast) formed colonies, with the addition of 2-mercaptoethanol (2-ME). Under low oxygen tension, the CFU-mast formed colonies without 2-ME, but a further enhancement was observed with the addition of 2-ME. Blood gas analysis of human bone marrow showed a pO2 of 51.8 +/- 14.5 mmHg, which was closed to O2 tension in a gas phase culture media containing 7% O2. This data shows that the physiological O2 tension enhances hemopoietic stem cell proliferation in vitro, and that a part of the enhancing effect by 2-ME is due to a prevention of O2 toxicity at 19% O2.