Effect of donor age on epidermal growth factor processing in man.

Epidermal growth factor (EGF) is a well-characterized mitogen whose effectiveness decreases with age both in vivo and in vitro. Previous studies utilizing the Hayflick aging model of early versus late-passage fibroblasts failed to demonstrate changes that might account for the unresponsiveness. In contrast, we now report striking differences in EGF receptor (EGFR) number, affinity, and rate of EGF/EGFR internalization in early-passage dermal fibroblasts derived from newborn versus young adult versus old adult donors. These data demonstrate critical differences between the two models of cellular aging, provide an explanation for the age-associated loss of EGF responsiveness, and may explain in part the tendency toward impaired wound healing in the elderly.