CHARACTERIZATION OF THE DIFFERENTIATED PHENOTYPE OF AN ORGANOTYPIC MODEL OF SKIN-DERIVED FROM HUMAN KERATINOCYTES AND DRIED PORCINE DERMIS

A number of skin models have been developed, but a simple method for r apidly producing large quantities of differentiated epidermis has been missing. We show the differentiated phenotype of human keratinocytes in organo-typic culture arising in vitro by air-exposure of keratinocy tes cultured with feeders on dried pig dermis. Keratinocytes were seed ed at low density on the dermis covered with irradiated NIH-3T3 feeder cells and after reaching confluence lifted to the air-medium interfac e. A well differentiated epidermis with distinct basal, spinous, granu lar and stratum corneum layers was formed within 1 week. In this way, 100 cm(2) of the differentiated recombined human/pig skin (D-RHPS) can be obtained from 10(6) secondary keratinocytes in 14 days. The entire keratinocyte life cycle takes place on the dermal substrate - from si ngle cells to stratified epidermis. The differentiation was characteri zed using a panel of monoclonal antibodies. Similarly as in the normal skin, keratin 14 aas expressed in all cell layers, keratin 10 in supr abasal layers, beta 1-integrin and epitopes to antibody LH8 in the bas al layer, involucrin and transglutaminase in the granular and horny la yer of the epidermis. Keratins 16 and 7/17, which are absent in the no rmal epidermis, but present suprabasally in the psoriatic one, were ex pressed strongly in all suprabasal layers and in a subpopulation of ba sal cells. The keratinocytes can be combined with two other cell types cultured either on the dermal side of the dermis and/or on the bottom of the dish. It appears that this simple skin model can be used in st udies of epithelial/mesenchymal interactions and interactions between epidermal cells and infectious agents. It may be particularly useful f or the study of human papilloma viruses.