Heparin-fibroblast growth factor-fibrin complex: in vitro and in vivo applications to collagen-based materials.

Biological molecules such as fibrin and growth factors could have interesting features to design bioactive biomaterials and particularly collagen-based materials used as connective tissue replacement. Different combinations of fibroblast growth factor (FGF) and heparin complexed to fibrin were analysed. In vitro, FGF bound to matrix was rapidly, but partially released, specifically with heparin. Heparin concentrations were progressively equilibrated between matrix and medium. DNA replication of fibroblasts grown either on or within fibrin matrices was increased in the presence of both FGF and high doses of heparin incorporated in fibrin. Subcutaneous implantations of collagen sponges impregnated with composite fibrin matrices showed qualitative and quantitative tissue ingrowth within the sponges. The uncross-linked collagen of fibrin-impregnated sponges swelled after implantation. The resulting fibroblast-infiltrated tissue resembled a normal dense connective tissue that was observed particularly in the presence of high doses of heparin and FGF incorporated in fibrin.