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

Abstract

Human diploid cells (WI 38) were serially subcultivated at partial pressures of oxygen [P(O2)] ranging from 5.6 mm Hg to 608 mm Hg. At a P(O2) of 5.6 mm Hg, the number of doublings to phase out was less than that of control cells at a P(O2) of 137 mm Hg. Cultures grown at P(O2)'s 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 P(O2)'s, a phenomenon that was, in part, reversible. d,l α Tocopherol (10 μg/ml or 100 μg/ml) homogenized into the medium at each weekly subcultivation did not extend the lifespan of cells at reduced, ambient, or elevated oxygen tensions. These results indicate that neither oxygen toxicity nor free radical reactions play a significant role in limiting the lifespan of WI 38 cells grown in vitro under ambient oxygen tensions [P(O2) 137 mm Hg].