Differentiation of Human Dermal Fibroblasts : a New Tool in Vascular Tissue Engineering

Sammanfattning: Tissue engineering is an expanding field, which focuses on the development of func-tional substitutes for damaged tissues. A limitation in this field is difficulties with obtaining autologous cells. Recent research has shown the presence of cells with multilineage-potential within the connective stroma of the skin. In line with this, a potential plasticity inherent in human dermal fibroblasts has been demonstrated. The overall aim of this study was to investigate if human dermal fibroblasts can be used as a cell source for vascular tissue engineering. Differentiation towards an endothelial cell-like phenotype was induced by culturing dermal fibroblasts in endothelial growth medium. By utilizing in vitro cell culture models, the capacity of different types of serum and serum constituents in inducing a phenotypic shift in fibroblasts was investi-gated. To clarify the mechanisms behind this phenotypic shift and to eliminate the risk of having growth of residual endothelial cells in the cultures, both normal dermal fibroblasts and single-cell clone fibroblasts were used. Our results demonstrated that presence of human serum caused fibroblasts and single-cell clone fibroblasts to express vWf, to incorporate fluorochrome-labeled low-density lipoprotein, and to start form-ing capillary-like networks. As an initial step in using these cells in tissue engineering, their ability to endothelialize a surface in vitro was studied. Cells cultured in either fibroblast or endothelial growth medium were seeded on scaffolds. Differentiation was confirmed by western blotting and immunohistochemistry using antibodies directed towards vWf, ve-cadherin, eNOS, and bradykinin receptor B2. The results revealed that endothelial differentiated fibroblasts cultured on scaffolds showed histological resem-blance to endothelial cells, and expressed molecules indicative of an endothelial phenotype. In conclusion, the results presented in this study indicate a possibility to induce differentiation of human dermal fibroblasts towards an endothelial cell-like phenotype. Consequently, these data suggests that human dermal fibroblast may be a novel cell source for vascular tissue engineering.