Effects of donor age on the expression of a marker of replicative senescence (EPC-1) in human dermal fibroblasts

EPC-1 (early population doubling level cDNA-1) is a quiescence-specific gene expressed at high levels by early passage WI-38 fibroblasts under conditions of either density-dependent growth arrest or serum deprivation. Late passage WI-38 cells lose the ability to express EPC-1 under all conditions tested. The decline in EPC-1 mRNA is gradual during the replicative life span and correlates inversely with the population doubling level (PDL) of the cells. The objective of this study was to determine whether the decline in EPC-1 mRNA abundance observed during proliferative senescence also occurs in cultures derived from donors of different ages. To address this question, we examined the abundance of EPC-1 mRNA in 28 skin fibroblast lines established from healthy donors of different ages ranging from 12 fetal weeks to 94 years. EPC-1 expression was measured, under conditions of growth arrest, prior to the end of the replicative life span of the cultures. Despite some variability in steady-state transcript levels among the cell lines, EPC-1 expression was significantly lower in cells derived from the fetal donor group (12-20 gestational weeks) than in cells derived from adult donors. An in vitro age-dependent decline in EPC-1 expression was observed in all the skin lines examined, independent of donor age; however, no significant difference was observed between the young adult donor group (17-33 years) and the old adult donor group (78-94 years). Thus, expression of EPC-1 is linked to the replicative age of the cells and whether the cells are derived from fetal skin or adult skin. In adults, EPC-1 expression is independent of donor age.