生体模倣傾斜機能アパタイトの生体内崩壊特性とBone Morphogenetic Protein-2用量依存性骨誘導実験

抄録

Biomaterial is indispensable for tissue engineering, and needs to biodegrade with bone formation. The aim of this study was to investigate the characteristics of biodegradation and the dose-response of bone induction morphohistologically in recombinant human BMP-2/HAp systems, based on different surface structures. Calcined bovine spongy bone apatite at 500-800℃ was designated as b-HAp. The fg-HAp was designed by the partial dissolution-precipitation method. The fg-HAp ceramics had a large specific surface area (200 m² /g), microcrystals about 10 nm in length, and Mg²⁺ or Na⁺ ions.
The fg-HAp block (3×3×3 mm) and the b-HAp (3×3×3 mm) containing 5.0, 1.0, 0.5, 0.3, 0.1, 0.05, or 0.0μg of BMP-2 were implanted into the back subcutis of 4-week-old Wistar rats. At 3 weeks after implantation, the implanted blocks were explanted, and the degradation of the ceramics and the induction of hard tissues were evaluated morphohistologically.
Ectopic bone induction occurred in the fg-HAp/BMP2 (5.0, 1.0, 0.5, 0.3 μg) system at 3 weeks, while in the bHAp/BMP-2 (5.0 μg), only bone induction was found. Interestingly, the biodegradation of the fg-HAp and bone induction occurred simultaneously in the fg-HAp/BMP-2 system.The excellent bone induction and biodegradation in the fg-HAp/BMP-2 system might result from the increase of BMP-2 affinity/binding sites and artificial nano-micro pores. The results also suggest that the retention amount of BMP-2 must be enough to induce ectopic bone formation, compared to the b-HAp/BMP-2 system.