Aging of Cells in Culture

Publisher Summary The chapter discusses experimental results obtained using fibroblast-like cells that give some indications of the possible mechanisms that limit the division capacity of normal cells in culture. It focuses on the newer cell-culture models involving cells that retain differentiated functions in culture and their possible contribution to determining the relationship between in vitro and in vivo cellular aging. The in vitro growth of normal somatic cells is characterized by an inherent limitation of their proliferative potential. The number of population doublings a cell strain can undergo is a distinct phenotypic characteristic independent of the chronological age of the culture. Although there is evidence that specific additions to the culture medium—such as hydrocortisone and fibroblast growth factor (FGF)—may extend the proliferative capacity of human and bovine cells, respectively, they ultimately cease division. The population-doubling level of the cultures at the time of hydrocortisone or FGF addition is critical in obtaining the maximum lifespan extension. The lower the population doubling level of the culture when treated, the larger the cumulative number of population doublings accrued. The remarkable consistency of normal cells in culture to express a limited in vitro replicative lifespan, which is inversely related to the age of the donor from which the cell culture was initiated, has led to their utilization as models for cellular aging.