A comparison of the proliferative and replicative life span kinetics of cell cultures derived from monozygotic twins.

We have compared the growth rates, kinetics of cell aging, and replicative life spans of skin fibroblasts cell cultures derived from three pairs of monozygotic twins of similar ages. The results of these studies indicated no significant differences in the cell densities 7 days after inoculation or replicative life spans within each twin pair but highly significant differences among each twin pair. The kinetics by which each culture aged ([3H]thymidine-labeled nuclei) were compared within and among the twin cell cultures. Although the slopes of each regression line were not significantly different, comparisons of the elevations of each line supported the conclusion that the aging of monozygotic twin cell cultures is similar within the twin pairs but differs among the twin pairs.