Development and testing of a human collagen graft material

Abstract

Human Type I collagen was extracted from placenta using pepsin and salt fractionation. The collagen was characterized by SDS‐PAG electrophoresis dispersed in acidic medium, freeze‐dried, and crosslinked in a 0.25% glutaraldehyde solution pH 4.5 for 2 days. After washing for 7 days and freeze drying the resultant collagen sponge was tested with regard to mechanical, physical, enzymatic degradation properties and biological responses. The modulus of elasticity was found to be 289 ± 10 g/mm² and the sponge was in soluble in water, buffered saline, or tissue culture medium over a period of 6 weeks with swelling occurring at less than 5% of volume. The sponge had a high fluid binding capacity, amounting to 56 ± 5 mL tissue culture medium per gram of dry weight. Bacterial collagenase produced slow degradation of the sponge with colmplete disappearance by 24 h only when concentrations (200 units enzyme per mg of the collagen sponge) were used. Cytotoxicity studies using human gingival and periodontal ligament fibroblasts revealed less than 5% apparent cytotoxicity or proliferation. Subcutaneous implantation was folllowed by resorption and vascularization over a period of 6–8 weeks. It was concluded that the collagen sponge prepared from human Type I collagen has potential as a graft material in oral surgical procedures.