ＢＭＰ‐チタニア（ＴｉＯ２）複合体の骨髄腔内，骨欠損腔内での骨形成能

Abstract

To investigate new biomaterial possessing active osteogenetic competence in hard tissue, half-purified bone morphogenetic protein (BMP) was combined with sintered titanium dioxide (titania). BMP-titania complex was implanted in bone marrow cavities and bone defects.In this experiment titania was used as a carrier of BMP, therefore the mechanical properties of titania were investigated initially, and then the effects of titania on BMP activity were studied in vitro. The biaxial flexure strength of titania was 133.8±9.33MPa, diametral tensile strength was 29.9±7.48MPa, compressive strength was 262.7±33.04MPa, and Vicker's hardness was 628.1±45.13Hv. Titania neither enhanced BMP activity, nor suppressed it. This may indicate possible use as a carrier of BMP.For the implantation of BMP-titania complex, three mg of BMP bound into a hollow titania cylinder with an external diameter of 4mm, an internal diameter of 2mm, and a length of 5mm, was deeply implanted into the marrow cavities and bone defects of the femur of Japanese white rabbits. Four weeks after implantation, all animals were sacrificed, and the tissue in the hollow part of the titania cylinder was observed histologically using H-E., toluidine blue, and tetrachrome staining.The results showed BMP-titania complex to have osteogenetic competence in both bone marrow cavities and bone defects. As a result of the histologic observation of the ossification process, it is suggested that ossification by BMP in marrow cavities is not via chondrogenesis. In conclusion, the BMP-titania complex can act as a bone substitute.