骨形态发生蛋白2复合纤维蛋白凝胶促进兔胫骨牵张成骨

Recombinant human bone morphogenetic protein-2/fibrin gel enhances bone formation in a rabbit model of tibial distraction osteogenesis

背景:关于药物缓释载体携载骨形态发生蛋白2在骨折愈合和骨缺损中的研究报道较多,但其在牵张成骨中的作用研究较少。目的:探讨人重组骨形态发生蛋白2(recombinant human bone morphogenetic protein-2,rhBMP-2)复合纤维蛋白凝胶对兔胫骨牵张成骨骨形成的作用。方法:采用酶联免疫吸附测定法检测rhBMP-2复合纤维蛋白凝胶的体外释放动力学。取48只健康新西兰大白兔,选取右侧胫骨行牵张成骨,胫骨延长10 mm后,随机分4组干预,牵张间隙内分别注射赋形剂(对照组)、纤维蛋白凝胶、rhBMP-2、rhBMP-2复合纤维蛋白凝胶。注射4,8周后,进行牵张胫骨X射线检测;注射8周后,进行Micro-CT、生物力学及组织学检测,观察牵张区骨痂成骨情况。结果与结论:(1)体外药物释放实验显示,纤维蛋白凝胶可延长体外rhBMP-2的作用时间,整个周期可达17 d;(2)X射线显示,rhBMP-2复合纤维蛋白凝胶组牵张间隙内放射密度最高,皮质骨连接最好;(3)Micro-CT显示,rhBMP-2复合纤维蛋白凝胶组牵张区骨矿物质密度、骨体积分数、皮质骨厚度明显优于其他3组(P<0.05);(4)组织学观察显示,rhBMP-2组、rhBMP-2复合纤维蛋白凝胶组牵张间隙皮质骨形成和骨连接效果好于对照组、纤维蛋白凝胶组,且rhBMP-2复合纤维蛋白凝胶组牵张间隙皮质骨形成和骨连接效果好于rhBMP-2组;(5)生物力学测试显示,rhBMP-2组、rhBMP-2复合纤维蛋白凝胶组极限载荷高于对照组、纤维蛋白凝胶组(P<0.05),且rhBMP-2复合纤维蛋白凝胶组极限载荷高于rhBMP-2组(P<0.05);(6)结果表明,纤维蛋白凝胶是一种理想的rhBMP-2缓释载体,rhBMP-2复合纤维蛋白凝胶可促进兔胫骨牵张成骨中的骨形成。

BACKGROUND:Numerous reports have been made on the use of bone morphogenetic protein-2 suspended in sustained release carrier in the fracture healing and bone defect repair.However,little is reported on its effect during distraction osteogenesis.OBJECTIVE:To investigate the effect of recombinant human bone morphogenetic protein-2(rhBMP-2)suspended in fibrin gel on bone formation during distraction osteogenesis in rabbits.METHODS:The in vitro release kinetics of rhBMP-2 suspended in fibrin gel was tested using an enzyme-linked immunosorbent assay.Unilateral tibial lengthening 10 mm was achieved in 48 healthy New Zealand rabbits.After the completion of osteodistraction,vehicle,fibrin,rhBMP-2 or rhBMP-2 suspended in fibrin(rhBMP-2+fibrin)was injected into the center of lengthened gap in the corresponding group with 12 animals in each group.At 8 weeks after injection,distracted callus was examined by histological,Micro-CT and biomechanical tests.Radiographs of the distracted tibia were taken at both 4 and 8 weeks after injection.RESULTS AND CONCLUSION:Fibrin gel prolonged the life span of rhBMP-2 in vitro with a sustained release during 17 days.The rabbits undergoing treatment with rhBMP-2+fibrin gel showed the best results in radiation density and cortical bone connection by the radiological observation,in bone mineral density,bone volume fraction,and cortical bone thickness by the Micro-CT evaluation and in ultimate load by the biomechanical test when compared to other groups(P<0.05).In histological images,rhBMP-2+fibrin treatment showed increased callus formation and better gap bridging compared to the other groups.To conclude,fibrin gel holds the promise to be a good carrier of rhBMP-2,and rhBMP-2 suspended in fibrin promotes bone formation in the rabbit model of tibial distraction osteogenesis.