Morphological and functional differentiation in epithelial cultures obtained from human skin expiants

Abstract

The present study was undertaken to characterize primary epithelial cultures obtained from human skin explants as experimental systems for studies of the differentiation process. When human skin expiants were incubated at 34–35° C, fibroblastic growth was strongly inhibited, whereas the epithelial growth proceeded unchanged. The lateral growth of the epithelial cells could be divided into two phases-a migratory and a proliferative one. Only cultures incubated at 35° C or below completed the morphological differentiation process before sloughing, whereas no qualitative difference in protein synthesis was observed between cultures incubated at temperatures from 33-37° C. Cultured epidermal cells were labelled with³H-thymidine and analysed by flow cytometry and cell sorting. Cells sorted from the S-and G₂-phase populations were further analysed by autoradiography and a considerable heterogeneity as to the nuclear labelling was disclosed. A large fraction of S-phase cells were found to be totally unlabelled. The grain count distributions revealed similar cell cycle subpopulations as have been shown to occur in vivo. The relationship of these subpopulations to the differentiation process is discussed.