Colony size distribution as a measure of age in cultured human cells. A brief note

Individual human diploid cells from the same culture differ greatly in the number of doublings they can achieve and consequently the size of colony they can initiate. Computer simulations suggested that the life-span of a culture could be determined from the distribution of colony sizes. Colony size distributions of cultures of a human diploid fibroblast, WI-38, were determined experimentally and found to be a sensitive measure of in vitro age. In particular, there is a highly significant linear correlation between the percentage of colonies of sixteen or more cells and the number of population doublings remaining in the in vitro life-span. Thus, the colony size distribution can be used to predict the number of population doublings remaining in the vitro life-span of a human diploid fibroblast cell culture without knowledge of its prior history.