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 maj or requirement for patient recovery, Although many skin substitutes ha ve been described, permanent regeneration of both epithelial and conne ctive tissues after a single surgical application of a skin substitute has not become routine. To replace both dermal and epidermal skin, cu ltured skin substitutes (CSS) were prepared from autologous keratinocy tes and fibroblasts seeded onto collagen-glycosaminoglycan (C-GAG) sub strates. CSS were applied to excised, full-thickness burns on 5 patien ts, Histologic analysis showed a fully stratified, hyperkeratotic epid ermis within 12 days of grafting with little to no evidence of an infl ammatory reaction. Epidermal and connective tissues are interdigitated in analogy to rete pegs and dermal papillae, and the neovascular plex us approximates the dermal epidermal junction, Transmission electron m icroscopy identified a continuous basement membrane with hemidesmosome s and anchoring fibrils that connected the epidermis with the underlyi ng connective tissue. Within 14-28 days, the C-GAG had been degraded a nd replaced by newly synthesized collagen in regenerated connective ti ssue, Spontaneous repigmentation of healing CSS from passenger melanoc ytes in keratinocytes culture was observed within 2 months after graft ing. Electron microscopy revealed the presence of numerous melanosomes within the Ireratinocytes, illustrating pigment transfer between mela nocytes and keratinocytes after wound closure. These results demonstra te that the CSS develop into functional permanent skin tissue capable of spontaneous repigmentation after grafting onto burn wounds.