Fibronectin matrix formation by human fibroblasts on surfaces varying in wettability

The spatial organization of extracellular fibronectin on biomaterial surfaces might be important for interaction with tissue cells. In previous investigations we have demonstrated that hydrophilic materials bind preadsorbed fibronectin that can easily be reorganized by fibroblasts in a specific matrix-like structure, while on less wettable materials (possessing water contact angles above 60 deg) the cells were unable to do this. As the cells continuously produce their fibronectin matrix, we tried in this study to answer the question of how the surface wettability of biomaterials influences the endogenous fibronectin matrix formation and its subsequent organization on the substrate. We cultured fibroblasts for 72 h on five different wettable surfaces: glass, aminopropyltriethoxysilane, pellethane, polyvinylchloride, and silicone, with water-contact angles gradually ranging from 25 to 105 deg. We demonstrated that the decreasing wettability of the materials significantly reduced endogenous fibronectin deposition on the substratum. Moreover, fibrillar organization of fibronectin appeared only on relatively hydrophilic glass and APS substrate, while on more hydrophobic materials like PVC and SI, cells secreted some fibronectin but were not able to organize it into a fibronectin matrix. These results were correlated with an altered cell morphology and spreading on these materials. In addition, an ELISA method has been implemented to quantify fibronectin matrix formation as a possible measure of the biocompatibility of materials, where a clear relation has been found between fibroblast growth and fibronectin matrix formation.