Barrier function in reconstructed epidermis and its resemblance to native human skin

One of the prerequisites for the use of human skin equivalents for scientific and screening purposes is that their barrier function is similar to that of native skin. Using human epidermis reconstructed on de-epidermized dermis we demonstrated that the formation of the stratum corneum (SC) barrier in vitro proceeds similarly as in vivo as judged from the extensive production of lamellar bodies, their complete extrusion at the stratum granulosum/SC interface, and the formation of multiple broad lamellar structures in the intercorneocyte space. The presence of well-ordered lipid lamellar phases was confirmed by small-angle X-ray diffraction. Although the long periodicity lamellar phase was present in both the native and the reconstructed epidermis, the short periodicity lamellar phase was present only in native tissue. In addition, the SC lipids predominantly formed the hexagonal sublattice. Analysis of lipid composition revealed that all SC lipids are synthesized in vitro. Differences in SC lipid organization in reconstructed epidermis may be ascribed to the differences in fatty acid content and profile indicating that further improvement in culture conditions is required for generation of in vitro reconstructed epidermis with stratum barrier properties of the native tissue.