The immortalized human keratinocyte line, HaCaT cells have been widely used as substitutes for normal epidermal keratinocytes. Recently, reconstruction of a skin equivalent using HaCaT cells showed a multilayered epithelium,but somewhat different tissue architecture as compared with normal epidermis.

In this study, using HaCaT cells we tried to reconstruct an epidermis resembling more closely to normal epidermis than the previous results.

HaCaT cells were cultured in air-liquid interface on a recently developed dermal substrated in our laboratory, de-epidermized dermis (DED) raised on fibroblast-populated collagen matrix and the result was compared with those on DED or fibroblast-populated collagen matrix alone.

HaCaT cells on the new dermal substrate formed a multilayered epithelium with rete ridges, showing rather orderly cellular organization compared with those on fibroblast-populated collagen matrix. However, horny and granular layers were not observed contrary to normal epidermis. Immunohistochemical studies revealed that differentiation markers such as keratin 1, keratin 6 and involucrin showed the similar pattern to those in HaCaT cells cultured on fibroblast-populated collagen matrix. Markers of terminal differentiation, loricrin and filaggrin were not expressed contrary to normal epidermis.

These results suggest that organotypic culture HaCaT cells on the dermal substrate combines DED with fivroblast-populated collagen matrix results in incomplete differentiation of HaCaT cells contrary to normal keratinocytes.