负载不同浓度骨形态发生蛋白的组织工程骨体内成骨的量效关系

The dose-effect correlation between tissue engineered bone loaded BMP at different densities and new bone formation in vivo

目的以聚乳酸-羟基乙酸[poly-(D,L-lactide-co-glycolide),PLGA]为支架,负载不同浓度的骨形态发生蛋白(bonemorphogeneticprotein,BMP),与骨髓基质干细胞(bonemarrowstemcells,BMSCs)构建成新型的组织工程骨,并观察其体内成骨的量效关系。方法制作新西兰大白兔桡骨中段15mm骨缺损实验模型,植入不同含量BMP的组织工程骨。24只兔随机分为三组:第一组:植入同时负载5.0mgBMP及1×106个已向成骨细胞诱导的BMSCs的组织工程骨(10只);第二组:植入同时负载2.5mgBMP及1×106个已向成骨细胞诱导的BMSCs的组织工程骨(7只);第三组:植入同时负载1.0mgBMP及1×106个已向成骨细胞诱导的BMSCs的组织工程骨(7只)。术后对动物进行大体观察,摄X线片观察各组术后4、8、12周骨缺损修复情况,比较不同时相的骨缺损区X线阻射密度。于术后第4、8、12周取出骨缺损区标本进行大体观察和组织学切片观察,图像分析骨缺损区域骨小梁的生成数量;取第12周标本行生物力学检测。结果X线片显示术后4周三组动物的桡骨缺损区域均有明显骨痂生成;12周时三组的骨缺损完全愈合率分别为7/8、3/5、3/5;各时相局部X线阻射密度值与新生骨小梁百分比计量显示第一组的新生骨痂及骨小梁最多,并可见髓腔再通现象。生物力学检测结果显示第一组的压缩刚度、扭转刚度、三点弯曲断裂载荷均大于其他两组。结论含5.0mgBMP的PLGA支架与BMSCs复合构建的组织工程骨修复兔桡骨15mm骨缺损的效果最佳。

Objective To investigate the effect of a kind of tissue engineered bone implants on healing of segmental bone defects. Methods A 15 mm bone defect experimental model at the right radius of New Zealand white rabbit was made. 24 animals of this model were divided into three groups at random. PLGA scaffords loaded with 5 mg BMP and about lxl06 BMSCs were implanted in Group 1 （n=10）; PLGA scaffords loaded with 2.5 mg BMP and about lxl06 BMSCs were implanted in Group 2（n=7）; PLGA scaffords loaded with 1 mg BMP and about lxl06 BMSCs were implanted in Group 3 （n=7）. The osteogenesis at the de.feet area was observed by regular roentgenography and X-ray analysis, histological changes at the bone defects at 4th, 8th, 12th weeks after operation were studied and the new bone formation was measured by image analysis. Biomechanical analysis was clone 12 weeks after operation. Results A large quantity of callus was found in all the 3 groups 4 weeks after repair. At the 12th week, the complete bone healing rate was 7/8, 3/5, 3/5, respectively in Group 1, 2 and 3. Group 1 had the largest quantity of new bone measured by histopathological study and X-ray analysis, and at the 12th week, the medullary cavity in this group became united. The compress stiffness, torsion stiffness and the maximal load in Group 1 were better than those in other groups. Conclusion The tissue engineered bone contructed by PLGA scaffords that are loaded with 5 mg BMP and BMSCs is capable of repairing segmental bone defects.