DIRECT COMPARISON OF A CULTURED COMPOSITE SKIN SUBSTITUTE CONTAINING HUMAN KERATINOCYTES AND FIBROBLASTS TO AN EPIDERMAL SHEET GRAFT CONTAINING HUMAN KERATINOCYTES ON ATHYMIC MICE

This study compares two techniques for making cultured skin substitute s: a composite graft made of human fibroblasts and keratinocytes on a collagen-glycosaminoglycan membrane (CG) and a cultured epidermal cell sheet graft (CEG) without a dermal component. The ''take'' and qualit y of these cultured skin substitutes were evaluated by placing them on full-thickness, excised wounds of athymic mice. These cultured skin s ubstitutes were placed onto 2-X-2-cm wounds created on athymic mice. M ice were sacrificed at days 10, 20, and 42 with histologic sections ob tained for light, electron, immunofluorescent, and immunohistochemical microscopy. ''Take'' was determined separately by a direct immunofluo rescent stain for human leukocyte ABC antigens. There were ten mice of each graft type with at least two animals sacrificed at each time poi nt. Results showed positive ''take'' for all animals. Grossly, there w as little difference between the two graft types, with the CEG having occasional blister formation. By light microscopy, the CEG had a disso ciation of dermis from epidermis until day 42, which was never apparen t with the CG. By day 42, the CG had increased dermoepidermal interdig itations similar to rete ridges, with a mature epithelium. Neither of these findings were seen with the CEG. Immunofluorescent and immunohis tochemical microscopy for type IV collagen and laminin, as well as ele ctron microscopy, showed similar retardation of basement membrane form ation with the CEG. Using this model, the composite graft had signific ant advantages over the epidermal sheet graft in the closure of full-t hickness wounds.