No male-female difference in vitro lifespan of skin fibroblasts from humans and mice

To determine if the difference in mean survival time of males and females is related to the mechanism restricting the number of in vitro cell doublings, we established cultures of human skin fibroblasts and murine embryo cells. The maximum number of in vitro doublings was found to be very similar for the two sexes in both species. Furthermore, human cultures receiving repeated treatments with three alkylating carcinogens had the same in vivo survival as untreated controls.