Long-term organ culture of rabbit skin: effect of EGF on epidermal structure in vitro.

A method is described for maintaining the epidermal structure of normal rabbit ear skin explants in organ culture for up to 12 weeks. Split-thickness skin specimens were put in diffusion chambers made of either millipore filters or bovine collagen membranes, and then submitted to a roller tube culture at 15 rpm and 36 degrees C. The culture medium was Dulbecco's modified Eagle's medium (DMEM) supplemented with 20% fetal calf serum (FCS) + 0.4 micrograms/ml hydrocortisone. The gas used in the culture tube was air + 5% CO2. Autoradiography revealed the incorporation of [3H]-glycine into the 68-kD keratin band of explants for up to 12 weeks, indicating that normal keratinization was maintained throughout the entire culture period. The turnover time of the epidermis from basal layer to granular layer was around 7 d in both the early and late stages of culture. The addition of epidermal growth factor (EGF) to the culture caused the epidermis to become acanthotic with orthokeratosis, but with high concentrations of EGF (greater than or equal to 10 ng/ml) parakeratosis and increased proliferation of the epidermis occurred. Dexamethasone (DMS) strongly inhibited the EGF effect.