Kuboki Y, Takita H, Kobayashi D, Tsuruga E, Inoue M, Murata M, Nagai N, Dohi Y, Ohgushi H
Department of Biochemistry, School of Dentistry, Hokkaido University, Sapporo, Japan.
J Biomed Mater Res. 1998 Feb;39(2):190-9. doi: 10.1002/(sici)1097-4636(199802)39:2<190::aid-jbm4>3.0.co;2-k.
Bone morphogenetic protein (BMP) is known to require a suitable carrier to induce ectopic bone formation in vivo. Hydroxyapatite ceramics have been reported to be effective in some forms but ineffective in others as a carrier of BMP-induced bone formation. In this study we compare three geometrically different forms of hydroxyapatite to examine their functions as carriers of BMP-induced bone formation. A fraction containing all the active BMPs (BMP cocktail) was partially purified from a 4M guanidine extract from bovine bone by a three-step chromatographic procedure. The BMP cocktail was combined with each of three forms of hydroxyapatite--solid particles (SPHAP), porous particles (PPHAP), and coral-replicated porous tablets (coral-HAP)--and implanted subcutaneously into rats. Both the PPHAP and coral-HAP systems induced osteogenesis 2 weeks after implantation, as evidenced by morphological and biochemical observations. Details of the osteogenetic process were followed by double-fluorescence labeling in the coral-HAP system to confirm bone formation on the surface of hydroxyapatite. However, there was no evidence of osteogenesis or chondrogenesis in the SPHAP system. The results indicate that the geometry of the interconnected porous structure in PPHAP and coral-HAP create spaces for vasculature that lead to osteogenesis while the smooth structure and close contact of particles in SPHAP inhibit vascular formation and proliferation of mesenchymal cells, preventing bone and cartilage formation. It was concluded that the geometrical structure in hydroxyapatite ceramics that induces vasculature is crucial as a carrier for BMP-induced bone formation.
已知骨形态发生蛋白（BMP）在体内诱导异位骨形成需要合适的载体。据报道，羟基磷灰石陶瓷作为BMP诱导骨形成的载体，在某些形式下有效，而在其他形式下无效。在本研究中，我们比较了三种几何形状不同的羟基磷灰石形式，以研究它们作为BMP诱导骨形成载体的功能。通过三步色谱法从牛骨的4M胍提取物中部分纯化出含有所有活性BMP的组分（BMP混合物）。将BMP混合物与三种形式的羟基磷灰石——固体颗粒（SPHAP）、多孔颗粒（PPHAP）和珊瑚复制多孔片（珊瑚-HAP）——分别混合，并皮下植入大鼠体内。形态学和生化观察表明，PPHAP和珊瑚-HAP系统在植入后2周均诱导了成骨。在珊瑚-HAP系统中通过双荧光标记追踪成骨过程的细节，以确认羟基磷灰石表面的骨形成。然而，在SPHAP系统中没有成骨或软骨形成的证据。结果表明，PPHAP和珊瑚-HAP中相互连通的多孔结构的几何形状为血管生成创造了空间，从而导致成骨，而SPHAP中颗粒的光滑结构和紧密接触抑制了血管形成和间充质细胞的增殖，阻止了骨和软骨的形成。得出的结论是，羟基磷灰石陶瓷中诱导血管生成的几何结构作为BMP诱导骨形成的载体至关重要。
