RECONSTRUCTION OF HUMAN EPIDERMIS ON DE-EPIDERMIZED DERMIS - EXPRESSION OF DIFFERENTIATION-SPECIFIC PROTEIN MARKERS AND LIPID-COMPOSITION

Using the Regnier-Prunieras method for the reconstruction of epidermis in vitro, a multilayered epidermis was obtained with an overall structure resembling that of native human epidermis. Evaluation of the expression and localization of a number of differentiation-specific protein markers revealed that human epidermis reconstructed on de-epidermized dermis shares some common features with hyperproliferating epidermis, such as the expression of keratin 6, and of involucrin, transglutaminase and filaggrin in suprabasal layers. Analyses of lipid content revealed that the air-exposed keratinocyte cultures reproduce to a high degree the lipids of the native epidermis, with the exception of higher triglyceride and lower glycosphingolipid content and a very low content of linoleic acid. The differences observed in the expression of differentiation-specific protein markers, as well as in the lipid composition, can be most probably attributed to the culture conditions used, since on culturing freshly excised skin under the air-exposed conditions similar deviations from the non-cultured tissue were observed as in the reconstructed epidermis. Using [C-14]linoleic acid and [C-14]acetate it was found that the air-exposed human keratinocyte cultures are capable of synthesizing all lipid species that are present in the native tissue. However, some lipid species are synthesized at rates that are different from those in vivo. This may explain the differences observed in the bulk lipid composition between reconstructed epidermis and its in vivo counterpart.