Unité de Thérapie Cellulaire, Hôpital Saint-Louis AP-HP, 1, Avenue Claude Vellefaux 75475 Paris cedex 10, France
Cell and tissue therapy applications in humans are being used increasingly, particularly for tissue repair. Several reconstructed skin models have been proposed. Wound healing involves overlapping steps of inflammation, cell migration and proliferation, neovascularisation, extracellular matrix production and remodelling. This is regulated by numerous cytokines and other soluble mediators. We have prepared dermal substitutes (DS) consisting of a collagen-GAG, three-dimensional matrix colonized by human dermal fibroblasts (HDF), isolated by skin explant or enzymatic digestion of the skin for potential therapeutic use in humans. To test the functionality of these DS, we measured (ELISA) the stimulatory effect on HDF in the matrix, of serial dilutions of human serum (HS) on the production of wound healing mediators: interleukin-8 (IL-8), vascular endothelial growth factor (VEGF), keratinocyte growth factor (KGF) and tissue inhibitor of metalloproteinase-1 (TIMP-1). We observed: 1) a stimulatory effect of HS on HDF production of the different mediators tested, with a dose-dependent effect in the case of IL-8 and VEGF. 2) A matrix-potentiating effect on the production of the different mediators by HDF. 3) A decrease in the production of IL-8 and VEGF when HDF isolated by enzymatic digestion was used to colonize the matrix as compared with HDF isolated by skin explant. We conclude: 1) that the production by HDF, in a collagen-GAG matrix, of mediators involved in cutaneous wound healing is decreased when HDF are isolated by enzymatic skin digestion rather than by skin explant. 2) That measurement of the production of cytokines or other mediators could be a useful quality control to test the functionality of tissue-engineered DS for tissue repair therapy in humans and more generally of cells prepared for cell therapy.