Pigmentation and microanatomy of skin regenerated from composite grafts of cultured cells and biopolymers applied to full-thickness burn wounds.

Rapid coverage and epithelial closure of extensive burns remains a major requirement for patient recovery. Although many skin substitutes have been described, permanent regeneration of both epithelial and connective tissues after a single surgical application of a skin substitute has not become routine. To replace both dermal and epidermal skin, cultured skin substitutes (CSS) were prepared from autologous keratinocytes and fibroblasts seeded onto collagen-glycosaminoglycan (C-GAG) substrates. CSS were applied to excised, full-thickness burns on 5 patients. Histologic analysis showed a fully stratified, hyperkeratotic epidermis within 12 days of grafting with little to no evidence of an inflammatory reaction. Epidermal and connective tissues are interdigitated in analogy to rete pegs and dermal papillae, and the neovascular plexus approximates the dermal-epidermal junction. Transmission electron microscopy identified a continuous basement membrane with hemidesmosomes and anchoring fibrils that connected the epidermis with the underlying connective tissue. Within 14-28 days, the C-GAG had been degraded and replaced by newly synthesized collagen in regenerated connective tissue. Spontaneous repigmentation of healing CSS from passenger melanocytes in keratinocytes culture was observed within 2 months after grafting. Electron microscopy revealed the presence of numerous melanosomes within the keratinocytes, illustrating pigment transfer between melanocytes and keratinocytes after wound closure. These results demonstrate that the CSS develop into functional permanent skin tissue capable of spontaneous repigmentation after grafting onto burn wounds.