骨形成蛋白-2基因修饰的β磷酸三钙/胶原复合材料修复颅骨缺损

Evaluation of Bone Regeneration by β Tricalcium Phosphate/Collagen Scaffold Loaded with Bone Morphogenetic Proteins 2 Plasmid in Rat Cranial Defect

目的构建骨形成蛋白2(Bone morphogenetic proteins2,BMP-2)基因修饰的β磷酸三钙(βtricalcium phosphate,β-TCP)/胶原复合支架材料,探讨其体内修复大鼠临界颅骨缺损的效果,评价其作为骨缺损修复材料的性能。方法制备纳米级多孔β-TCP/胶原支架,并负载100μg BMP-2质粒DNA形成基因修饰的支架材料。将24只成年雄性SD大鼠随机分为BMP-2基因修饰的β-TCP/胶原支架组(n=8),β-TCP/胶原支架组(n=8),空白组(n=8)。在大鼠颅骨顶部建立两个直径5mm的临界性骨缺损,植入材料后6周、12周取样本大体观察,组织学观察,免疫组织化学检测,并进行骨组织测量分析。结果组织学观察可见12周时,材料已完全降解。BMP-2基因修饰支架组6周时,骨缺损区成骨活跃形成编织骨;12周时,骨缺损已基本愈合,新生骨组织逐渐成熟呈板层状,与宿主骨形成骨性连接。而单纯支架组6周时,骨缺损中心区为少量岛状骨组织;12周时,新生骨组织连接呈片状,骨缺损未完全愈合。免疫组化检测显示:6周和12周时,BMP-2基因修饰支架组中BMP-2表达均强于单纯支架组和空白组。骨组织形态计量分析显示BMP-2基因修饰支架组成骨质量和成骨效率明显高于单纯支架组和空白组(P<0.05)。结论 BMP-2基因修饰的β-TCP/胶原复合材料具有良好的生物相容性,骨诱导和骨传导性佳,是很有潜力的新型骨缺损修复材料。

The osteoinductive properties of beta tricalcium phosphate（13-TCP）/collagen scaffold loaded with morphogenetic protein 2（BMP-2） plasmid （100μg） were evaluated in vivo. BMP-2 gene-modified β-TCP/ collagen scaffolds （n=8） were used to repair critically-sized defects （5ram in diameter） in the calvaria of rats, and pure β-TCP/collagen scaffolds （n=8） and empty defects （n=8） served as controls. The quality of newly regenerated bone was assessed by histological/histomorphometric analysis. The histological analysis revealed that porous β-TCP/collagen scaffold degraded completely at 12 weeks. Defects in BMP-2 DNA group healed completely whereas a significantly less bone ingrowth was observed in pure scaffolds by 12 weeks （p〈0.05）. Immunohistochemistry analysis indicated that the expression of BMP-2 was significantly stronger in BMP- 2DNA group than the controls （p〈0.05）, In addition, compared to pure scaffold groups or blank groups, rats in BMP-2 gene-modified scaffold group showed significantly more hone generation by histomorphometric analysis （P ~ 0.05）. We conclude that porous β-TCP/collagen scaffold loaded with BMP-2 DNA is an appropriate candidate for bone engineering.