[Kinetics of hemopoietic stem cells in hypoxic culture]

In an effort to develop more nearly optimal conditions for the clonal growth of hemopoietic stem cells (CFC, BFU-E, CFU-mix and Mast-CFC) iv vitro, I examined the influence of low oxygen tension (7% O2) on plating efficiency. The numbers of colonies derived from human bone marrow CFC increased by 1.7 fold in 7% O2 than under a gas phase containing air (19% O2). Bursts obtained from bone marrow BFU-E and mixed colonies from CFU-mix increased by about 2.5 fold in 7% O2. Total cell count of mixed colonies showed that the average cell per colony gassed with 7% O2 were 900 compared with 511 in 19% O2. However the subpopulation of CFC and composed cell type of mixed colonies were not different in the two gas phase. With mouse spleen cell in 7% O2 a dramatic increase in Mast-CFC numbers without 2-ME and decreased enhancement by 2-ME were seen. Blood gas analysis of human bone marrow showed a Po2 of 51.8 +/- 14.5 mmHg, which was close to O2 tension in culture media of gas phase contained 7% O2. These data showed that physiological O2 tension enhances hemopoietic stem cell proliferation in vitro, and that part of the enhancing effect by 2-ME is due to a prevention of O2 toxicity at 19% O2.