rhBMP-2在兔桡骨远端骨缺损模型中成骨效应研究

Osteogenic effect of recombinant human bone morphogenetic protein-2 on rabbit bone defect of the distal radius

目的评价大肠杆菌DH5α高度表达的重组人骨形态发生蛋白-2(rhBMP-2)促进兔桡骨远端骨缺损骨愈合的有效性和剂量-成骨关系。方法 72只成年雄性新西兰白兔按照所设rhBMP-2剂量随机等分为空白对照组、0.5 mg组和1.0mg组,右桡骨远端截骨构建骨缺损模型,分别于骨缺损处植入吸附rhBMP-2的纤维胶原蛋白载体复合物。术后2周、4周和8周每组分别处死动物8只,根据钼钯X线摄片、微CT检测、三点弯曲最大承载力测定和组织细胞学检查评估rhBMP-2成骨效应及剂量-成骨关系。结果 3个rhBMP-2剂量组术后2周、4周、8周Lane-Merchant评分所示骨愈合率有统计学差异(P<0.05)。根据微CT检测,所有标本正常骨密度无个体差异(P>0.078),3个rhBMP-2剂量组术后2周、4周、8周缺损区骨密度均有统计学差异(P<0.05);3个rhBMP-2剂量组术后2周、4周、8周三点弯曲最大承载力均有统计学差异(P<0.05)。组织细胞学检查结果也符合以上结果。结论 rhBMP-2(0.5 mg、1.0mg)能有效促进兔桡骨远端骨缺损愈合,其成骨能力在一定剂量范围内存在剂量依赖性。纤维胶原蛋白载体有着良好的生物相容性,但降解速度相对较快,对rhBMP-2缓释、提高局部有效浓度维持时间的作用有限。

Objective To estimate the effect and dose-osteogenesis relationship of the recombinant human bone morphogenetic protein-2 （rhBMP-2） highly expressed by bacillus coli DHSa in healing two-centimeter bone defect of the distal radius in a rabbit model.Methods Seventy-two adult New Zealand white rabbits were randomly and equally divided into three groups：rhBMP-20 mg （empty control）,0.5 mg and 1.0 mg.Each rabbit underwent a standard osteotomy in the distal of the right radius with a two-centimeter bone defect.The fibrin collogen scaffold with three different dosage of rhBMP-2 （0 mg,0.5 mgand 1.0 mg） were implanted into the region of bone defects according to the group assignment.Eight rabbits of each dosage group were killed respectively at 2,4 and 8 weeks postoperative.The specimens were collected and accepted molybdenum-palladium X-ray photograph,micro-CT scan,biomechanical test （three point flexion ultimate strength） and undecalcified histological section to estimate the effect and dose-osteogenesis relationship of the rhBMP-2.Results Calculated according to the grading standard of Lane-Merchant,the ratio of the bone defect healing of three different dosage groups obtained through the molybdenum-palladium X-ray photographs was compared using chi-square tests,significant statistical difference was observed among the three dosage groups at 2,4 and 8 weeks （P＜0.05）.Under the premise that the normal bone density data of all the samples was confirmed to have no significant difference （P＞0.078） through the statistical bone density data of micro-CT,the bone density data of the three different dosage groups at 2,4 and 8 weeks postoperative showed significant statistical difference （P＜0.05）.There were also significant statistical difference among the three different dosage groups at 2,4 and 8 weeks comparing the three point flexion ultimate strength data （P＜0.05） and histological findings also consistented with these results.Conclusions The rhBMP-2（0 mg,0.5 mg and 1.0 mg） is able to effectively promote the healing of bone defect of the distal radius in a rabbit model,the relationship of dose-osteogenesis has the dosa-dependent within a certain scope.The fibrin collogen carrier has the satisfactory biocompatibility and comparatively fast degradation.It had already been degraded 2 weeks later after surgery that shows the fibrin collogen has a limitation to the function of the carrier to retard the release of rhBMP-2 and increase the time of keeping the concentration of locally effective rhBMP-2.