Quantitative determination of EGF-R during epidermal wound healing.

Little is known about the intrinsic regulation of growth factors of cytokines during the normal epidermal wound-healing processes in skin. A simplified model of wounding (tape stripping to remove the stratum corneum) was used to study the role of epidermal growth factor receptors (EGF-R) in this process. Although the dynamics of EGF-R in epidermal wound healing have not been determined, the immunoreactive EGF-R that are present presumably play an active role. Prior studies show that 1) EGF-R are present in increased numbers in proliferative skin diseases; 2) a hypertrophic epidermis, closely resembling normal wound healing, is induced in mouse skin by EGF injections; and 3) exogenous topical EGF potentiates wound healing. The number of immunoreactive receptors as measured by an enzyme-linked immunosorbent assay (ELISA) and histologic methods increased prior to an increase in epidermal thickness, total protein, and DNA content. This early increase in the levels of EGF-R was followed by a sharp decline in EGF-R and subsequent decline in epidermal thickness (hypertrophy), total protein, and DNA levels. Alterations in the temporal sequence in these parameters indicate that the EGF-R-mediated signaling systems play an active role in epidermal wound repair.