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Dispase has been utilized to produce basal detachment of the epidermis of human skin biopsies and to study the consequences induced afterwards during incubations of the detached tissue. Spatial reorganization of the epidermis is observed under these conditions and is characterized by disappearance of the typical basal keratinocyte layer. Immunofluorescent labelings reveal upward migration of several cells exhibiting the basal phenotype between suprabasal differentiating keratinocytes and demonstrate progressive intracellular expression of hemidesmosomal components: the integrin alpha 6 beta 4 and two plaque components, the 230-kDa bullous pemphigoid antigen and HD1, a 500-kDa protein. Using electron microscopy and immunogold techniques, we demonstrate that the hemidesmosome-containing basal membrane domains enter the cell cytoplasm after detachment of the epidermal tissue. Partial recycling of internalized hemidesmosomal components is also suggested. Our findings illustrate the processing of released hemidesmosomes in detached basal keratinocytes and suggest some heterogeneity between basal cells migrating towards a suprabasal position and those remaining in the basal layer. These results suggest that the dispase-detached epidermis is a self-remodeling tissue in which basal keratinocytes' and tissue's polarities observed in the anchored epidermis are progressively changing.

Grafting of human cultured keratinocytes is a promising possibility for the treatment of large burned skin areas. However, during the preparation of cultures for grafting, a necessary step of detachment from culture substratum is performed by incubation with Dispase. In the present paper, we report studies performed to determine whether prolonged storage after detachment would have a detrimental effect on keratinocyte proliferation. Our results show that the number of bromodeoxyuridine-incorporating cells located in the basal layer of the culture gradually diminishes during storage of detached cultured epidermal keratinocyte sheets. Furthermore, the rate of [3H]thymidine incorporation in such detached cultures is also progressively reduced. These observations indicate that the detachment and storage of cultured epidermal keratinocyte sheets for grafting impedes their cell proliferation capacity, as revealed by DNA-synthesis measurements.