Rosdy, M., M. Fartasch, and M. Ponec. Structurally and Biochemically Normal Permeability Barrier of Human Epidermis Reconstituted in Chemically Defined Medium. J. Invest. Dermatol. 1996. 107(4): 664. Abstract #52. [Reprinted with permission from Blackwell Science, Inc.].

A fully differentiated epidermis is produced routinely in vitro by culturing normal human adult keratinocytes (NHK) on inert polycarbonate filter substrates at the air-liquid interface in modified and supplemented chemically defined medium MCDB 153. Vertical sections stained for histology and indirect immunofluorescence studies show a proper stratification and expression of major differentiation markers after 2 weeks of air-exposure. Up to 12 weeks of culture, the stratum corneum is continuously produced, and the thickness of the living layers stabilizes at a more reduced level. Electron microscopical studies (using ruthenium tetroxide-post fixation) show that the structural organization and distribution of the stratum corneum lipids in keratinocytes cultured for 18 days at the air-liquid interface is similar to that seen in the native epidermis. Supplementation of defined medium with linoleic and palmitic acids perturbed the structural organization of stratum corneum lipids and induced formation of triglyceride containing droplets. Biochemical analysis of epidermis lipids show that the lipid profile in the reconstituted epidermis is close to the in vivo situation, with appearance of free fatty acids and most of the ceramides responsible for the barrier function.