Human fibroblasts in vitro senesce with a donor-specific telomere length

In human fibroblasts, replicative senescence, telomere length and donor age are closely interrelated. We analyzed these relationships for fibroblast strains from 14 healthy human donors in the age range of 28-90 years. In vitro replicative capacity was correlated more closely with donor age than with telomere length ex vivo, especially for healthy donors. Telomere length at senescence was as variable as at cell explantation and increased with donor age. The data suggest a donor-specific, age-dependent regulation of the telomere length threshold that triggers senescence in human fibroblasts.