013 Gene Expression Profiling of Cultured Skin Substitutes

Abstract

Cultured skin substitutes (CSS) are used as an adjunctive treatment for closure of massive burn wounds. CSS are prepared with keratinocytes and fibroblasts combined with a collagen-based matrix. A cDNA microarray analysis was performed to characterize CSS at a molecular level. We hypothesized that combination of keratinocytes and fibroblasts in a three-dimensional organo typic culture system would result in changes in gene expression compared with cells grown in monolayer culture. Human skin samples were obtained from breast and abdominal tissue of healthy adult females. Fibroblasts and kera tinocytes were isolated and grown in monolayer cultures; CSS, prepared with cells from four independent donors, were cultured for 2 weeks in vitro. Microarray analysis was performed on RNA from fibroblasts, keratinocytes, and CSS using the Affymetrix Human Genome U133A gene chip representing over 22,000 human genes. Cluster analysis was performed to identify gene expression “signatures” for each group, and further analysis was performed to identify genes that were significantly increased or decreased in CSS compared with either cell type. Microarray analysis revealed significant changes in gene expression upon combination of fibroblasts and keratinocytes in organotypic culture. Genes belonging to several classes were significantly increased in CSS compared with fibroblasts and keratinocytes. For example, genes associated with epidermal differentiation, including fillagrin, corneodesmosin, involucrin, and multiple keratins (1, 10, 13, 16, 23), were increased in CSS. Several genes that are overexpressed in psoriasis (S100A7, SERPINB3, PSORS1C1), as well as cytokines IL- 6 and IL-8, were also increased in CSS. Further, multiple MMP genes were up-regulated in CSS. The results suggest that epithelial-mesenchymal interactions contribute to morphogenesis of CSS, including the remodeling of the dermal layer and stratification and differentiation of the epidermal layer. This analysis reveals that CSS exhibit many characteristics of normal or inflamed human skin.