In vitro evaluation of the inflammatory potential of the silk fibroin

Silk fibroin membranes recently have been suggested as matrices for biomedical applications, such as guided tissue regeneration and burn wound dressings. The aim of this study was to evaluate the inflammatory potential of fibroin films and to compare the fibroin films with two model materials with completely different physico-chemical properties: poly(styrene) and poly(2-hydroxyethyl methacrylate). Fibroin bound lower levels of fibrinogen than did the two synthetic polymers while the same amounts of adsorbed human plasma complement fragment C3 and IgG were detected. Studies of the binding strength of C3 to fibroin, evaluated by a novel experimental procedure, indicated the occurrence of strong hydrophobic interactions at the interface. The activation of the mononuclear cells by fibroin, measured as interleukin 1beta production, was lower than the reference materials. Adhesion experiments showed the ability of the macrophages to adhere to fibroin by filopodia without a complete spreading of the cells. The results achieved in this study demonstrate that the interactions of fibroin with the humoral components of the inflammatory system were comparable with those of the two model surfaces while the degree of activation and adhesion of the immunocompetent cells appeared more limited.