The Development for Osteoinductive and Biodegradable Bone Substitute Materials

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There are many cases to make bone defects in the oral and maxillo-facial region, for example cysts, cancers and so on. So Bone Morphogenetic Protein (BMP) is needed for clinical usage. And a lot of studies have been done to purify the BMP and to investigate the physiological function of that. Several reports suggested the possibility that BMP (Osteogenin, BMP-3 from demineralized bone matrix have stronger osteoinductive activity rather than rhBMP -2. Therefore the BMP was purified from the demineralized bone extract by gel filtration on Sephacry1 S-200HR, cation exchange with Mono-s, Heparin affinity column and finally by c1/8 reverse phase chromatography. The BMP preparation obtained in this study induced ectopic bone and marrow tissue in ectopic site in 2 weeks after implantation into the thoracic subcutaneous tissue. The results of 15% SDS-PAGE revealed the molecular weight in reduced condition is half that in non-reduced condition as reported before. Peptide sequence analysis revealed that the purified BMP fraction contained "BMP-3" reported by Wozney et al.A skull defect which is 8 mm in diamenter was prparated, and porus poly-L-lactic acid disc including the BMP was implanted into the defect. Osteoinductive activity induced by the disc was evaluated by means of soft X-ray image, calcium content, and histological observation. 2 weeks after implantation, bone tissue was induced and large value of calcium was detected in the excised discs. 4 weeks after implantation, also bone tissue was induced and larger value of calcium was detected from the excised discs. These results supported that the porus poly-L-lactic acid disc will be effective for recovery of bone defect.