The effect of oxygen and vitamin E on the lifespan of human diploid cells in vitro.

Abstract

Human diploid cells (WI-38 [embryo lung] cells) were serially subcultivated at partial pressures of O2 (PO2) ranging from 5.6-608 mm Hg. At a PO2 of 5.6 mm Hg, the number of doublings to phase out was less than that of control cells at a PO2 of 137 mm Hg. Cultures grown at PO2 of 24, 49 or 137 mm Hg grew at the same rate and phased out after a similar number of population doublings. Population lifespan was markedly shortened by chronic exposure to elevated PO2, a phenomenon that was, in part, reversible. d-l-.alpha.-Tocopherol (10 .mu.g/ml or 100 .mu.g/ml) homogenized into the medium at each weekly subcultivation did not extend the lifespan of cells at reduced, ambient or elevated O2 tensions. Neither O2 toxicity nor free radical reactions play a significant role in limiting the lifespan of WI-38 cells grown in vitro under ambient O2 tensions (PO2 137 mm Hg).