RECONSTITUTION OF HUMAN SKIN IN-VITRO USING READILY AVAILABLE SOURCES- NOVEL STUDIES OF TUMOR PROMOTION

As part of our development of an assay for skin tumour promoters we ha ve standardized a three-dimensional model of human skin. The important features of this model for our purposes are (a) that it is characteri stic of human skin, (b) that the developing epidermis can be seeded wi th ''initiated'' keratinocytes, and (c) that the calcium level of the medium can be controlled. The procedure used is an amalgamation of the methodologies of Asselineau and Prunieras (1984), Lenoir el al. (1988 ) and Rosdy and Clauss (1990). This model does not rely on a source of human skin and can be reproduced in any laboratory equipped with basi c cell culture apparatus. The dermal equivalent consists of human embr yonic fibroblasts and rat tail collagen. The overlying keratinocytes a re derived from the outer root sheath of human hair follicles inserted into the collagen-fibroblast gel. Stratification is induced by cultur ing the epidermal cells at the air interface of a serum-free medium. T he model has been characterized by histological staining, electron mic roscopy and immunostaining.