核心结合因子α1基因修饰骨髓间充质干细胞对骨缺损的修复研究

目的 探讨以核心结合因子α1（core-binding factor a1，Cbfa1）基因修饰骨髓间充质干细胞（marrow mesenchymal stem cells，MSCs）作为种子细胞，与猪脱细胞骨基质材料复合构建组织工程骨修复兔桡骨缺损的可行性。方法选择3月龄日本大白兔40只，建立桡骨1．2cm缺损模型，根据不同的修复方式分成4组。A组：Cbfa1基因修饰MSCs与脱细胞骨基质材料复合后修复；B组：未行基因修饰的MSCs与脱细胞骨基质材料复合后修复；C组：单纯脱细胞骨基质支架材料修复；D组：空白对照，不作任何植骨处理。术后4、8和12周分别行大体、X线片和组织学观察评价修复效果，并对修复后桡骨进行生物力学检测。结果大体观察至术后12周取材时，A组原骨缺损植骨区新生骨成熟度好、饱满、质硬；B组植骨区有骨性连接，质软；C组可在植骨区发现少量骨性连接；D组形成骨不连。X线片和组织学观察示：术后4、8周A组支架材料降解、新骨生成及髓腔再建优于其它3组。术后12周A组支架材料完全降解，新骨塑形完成，骨髓腔通畅，皮质骨改建成正常的板层骨结构；B组缺损区近端部分骨髓腔塑形再通；C组截骨两端骨痂向植骨中长入，髓腔塑形不明显；D组纤维组织充填，形成骨不连。以前述各组健侧桡骨为正常对照组（仍为D组），余分组同前，行破坏压缩载荷检测，结果示12周后A、B组与D组比较差异无统计学意义（P〉0．05），而C组与D组比较差异有统计学意义（P〈0．01）。结论Cbfa1基因修饰MSCs与脱细胞骨基质材料复合构筑的组织工程骨可较好地修复兔桡骨址螺

CORE-BINDING FACTOR α1 GENE MODIFIED MARROW MENSENCHYMAL STEM CELLS FOR REPAIRING RADIAL DEFECTS

OBJECTIVE: To study the feasibility of core-binding factor alpha1 (Cbfal) gene modified marrow mesenchymal stem cells (MSCs) composed with porcine acellular bone extracellular matrix in repairing the radial defects. METHODS: Radial defects of 1.2 cm in length were created in 40 Japanese white rabbits and they were divided into four groups. In group A, MSCs isolated from homogeneous rabbits were infected with Cbfal recombinant adenovirus and implanted into acellular bone exteracellular matrix, and then the complexes were implanted into defects. In group B, the complexes including the MSCs without Cbfal gene-modified and scaffold material were implanted into defects. In group C, only the scaffold material was implanted. In group D, defects were not treated as the control. The macroscopic, X-ray and histologic analysis were performed to evaluate the repair effect at 4, 8 and 12 weeks postoperatively. The repaired radius were examined by biomechanical test at 12 weeks postoperatively. RESULTS: By gross examination,mature hard new bone formed at grafted areas at 12 weeks postoperatively in group A, osteotomized ends connected by much callus in group B and less callus in group C at grafted areas. In contrast, bone nonunion formed in group D. X-ray and histological examination showed that the repaired results of defects in the group A were better than those in others groups evidently in extracellular matrix degradation, new bone remodeling and marrow cavity rebuilding at 4 and 8 weeks postoperatively. At 12 weeks postoperatively, the cortical bone became mature lamellar bone, new bone remolding was complete and marrow cavity was smooth in group A. Only proximal end of defects showed that marrow cavity was remolded partially in group B. The continuous callus could be observed in bone defect, and no obvious marrow cavity remolding was observed in group C. Lots of fibrous connective tissue filled in defect and bone nonunion was shown in group D. There was no significant difference in the damage compress loading of repaired radius between groups A, B and D (P>0.05), but there was significant difference between groups C and D (P<0.01). CONCLUSION: These results demonstrate that Cbfal gene modified MSCs combined with acellular bone extracellular matrix can be used to repair rabbit radial defects.