Topical Nutrients Promote Engraftment and Inhibit Wound Contraction of Cultured Skin Substitutes in Athymic Mice

Abstract

Routine treatment of burns with cultured skin substitutes (CSS) has been limited by poor engraftment and by scarring. Hypothetically, topical application of essential nutrients and/or growth factors may support epithelial survival temporarily during graft vascularization. CSS, composed of human epidermal keratinocytes and dermal fibroblasts attached to collagen-glycosaminoglycan substrates, were incubated for 19 d in media optimized for keratinocytes. CSS, human xenografts, murine autografts, or no grafts were applied orthotopically to full-thickness skin wounds (2 x 2 cm) in athymic mice. Wounds were irrigated for 14 d with 1 ml/d modified cell culture medium or with saline containing epidermal growth factor, or were treated with dry dressings. After 6 weeks, treated sites were scored for percentage original wound area (mean +/- SEM) and percentage HLA-ABC-positive healed wounds [(number positive/n) x 100], and tested for significance (analysis of variance, p < 0.0001; Tukey test, p < 0.05). The data showed that CSS irrigated with nutrient medium were not statistically different in wound area (67.8 +/- 5.1%) from murine autografts (63.3 +/- 2.9%) but were statistically larger than human xenograft, no graft, or CSS treated with saline irrigation or dry dressings. HLA-ABC expression was 100% in CSS with nutrient irrigation, 86% in CSS with saline irrigation, 83% in CSS without irrigation, and 75% in xenografts with nutrient irrigation. These findings suggest that availability of essential nutrients supports keratinocyte viability during graft vascularization of CSS.