骨形态发生蛋白2基因治疗在修复骨缺损中对血管化影响的实验研究

目的观察骨形态发生蛋白-2（BMP-2）基因治疗在修复骨缺损中对血管化的影响。方法分离培养兔骨髓基质干细胞（MSCs），经BMP-2腺病毒载体转染后复合异种骨支架移植修复1．5cm桡骨缺损。分为5组：①BMP-2基因转染细胞＋去抗原牛松质骨支架（BCB）；②未转染细胞＋重组BMP-2＋BCB；③对照基因转染细胞＋BCB；④未转染细胞＋BCB；⑤BCB。术后4、8、12周行微血管墨汁灌注、血管内皮生长因子（VEGF）免疫组化染色、组织学等检测。结果术后4周，基因治疗组骨间血管的密度在周边区域较高，通常每一个骨小梁孔隙中都有一支新形成的小血管；透射电镜见成骨细胞总是毗邻血管内皮细胞而存在，并随着微血管的增生而逐渐向骨细胞发展；间质细胞VEGF表达明显增强。结论BMP-2基因治疗可通过上调VEGF表达，间接诱导移植骨血管化，对骨不连、骨缺损的治疗具有重要意义。

Effects of BMP-2 gene therapy on vascularization in repairing bone defects

Objective To study the effects of BMP-2 gene therapy on vascularization in repairing bone defects.Methods The isolated rabbit mesenchymal stem cells(rBMSC),after being transfected by adenovirus carrying BMP-2 gene(Ad-BMP-2) and seeded on xenogeneic bone scaffolds,were used to repair 1.5 cm-long radius bone defects.Five methods were in use in the experiments: Ad-BMP-2 infected rBMSC plus antigen-free bovine cancellous bone(BCB,Group A),rBMSC-BCB plus reconstructed hBMP-2(Group B),Ad-LacZ infected rBMSC-BCB(Group C),rBMSC-BCB(Group D) and only BCB scaffolds(Group E).After 4,8,and 12 weeks of the operations,capillary vessel ink infusion,vascular endothelial growth factor(VEGF) immunohistochemical staining and histological examination were conducted.Results After 4 weeks of the operations,usually in Group A one newly formed artery was found in every pore between the trabeculae of the BCB.The density of these intraosseous vessels was high in the periphery and decreasing towards the center of the grafts;by transmission electron microscopy,osteoblasts were always next to vascular endothelial cells and gradually developed into osteocytes with the increase of capillary vessel;VEGF expression were apparently enhanced in mesenchymocytes.Conclusions BMP-2 gene therapy,by up-regulating VEGF expression,indirectly induces vascularization of grafts and is of great value to the treatment of bone ununion and bone defects.