干细胞移植和BMP2基因治疗修复骨损伤和坏死的实验研究

Repair of Bone Injury and Osteonecrosis with BMP2 Gene Therapy and Stem Cell Transplantation

目的:根据老年骨缺损和股骨头坏死实验模型的研究结果来评价干细胞移植和BMP2基因治疗的方法是否可用于一些特殊损伤和疾病的治疗。方法:从不同年龄段大鼠、羊骨髓中分离培养骨髓间充质干细胞,利用含BMP-2基因或βgal基因的腺病毒载体感染干细胞,通过酶联免疫测定方法检测基因转染细胞培养上清中BMP-2蛋白的含量。利用基因转染细胞和多孔三磷酸钙复合,回植后修复24月龄老年大鼠股骨干6毫米节段性缺损和实验性羊股骨头坏死。通过组织学观察和生物力学测定来评价比较BMP-2治疗组和βgal对照组的新骨形成情况和修复组织的强度。结果:基因转染细胞培养上清中BMP-2蛋白的含量随时间延长而逐渐上升,不同年龄大鼠干细胞BMP-2转染后蛋白质的分泌水平没有明显差异。组织学观察表明BMP-2基因转染细胞和多孔三磷酸钙复合物已成功修复24月龄老年大鼠股骨干6毫米节段性缺损和实验性羊股骨头坏死,BMP-2治疗组的新骨形成明显多于βgal对照组(P<0.05)。治疗后第16周,BMP-2治疗组股骨头修复组织的最大压缩强度和弹性模量也明显高于βgal对照组(P<0.05)。结论:BMP-2基因转染的自体骨髓间充质干细胞和多孔三磷酸钙复合后回植可有效修复老年大鼠骨缺损并重建羊坏死股骨头的功能。

Aim: To evaluate the available application of bone morphogenetic protein-2 (BMP2) gene therapy and stem cell transplantation in the treatment of some special cases of bone injury and disease based on the model of segmental bone defects in aged rats and experimental femoral head necrosis in goats. Methods: Bone marrow derived mesenchymal stem cells(MSCs)from goats or rats of different ages were infected by the adenoviru vectors containing BMP2 gene or gal gene. BMP2 proteins secreted from gene modified cells were assesed by the method of ELISA. Gene modified MSCs/ Porous -triphosphate (-TCP) were used to repair both the femoral bone defects of 6mm in length in aged rats and the experimental femoral necrosis induced by ligation of circum- flex femoral arteries and perfusion of liquid nitrogen. Histological observation and biomechanical testing were used to evaluate and compare the bone formation and bone strength between BMP2 treatment group and gal control group. Results: Concentrations of BMP2 proteins in cell culture supernates increased with time after BMP2 gene transfer. There is no significant difference in BMP- 2 concentrations between cells from rats of different ages. Histological observation demonstrate that the BMP2 gene modified MSCs/ -TCP have successfully repaired femoral bone defects inaged rats and experimental osteonecrosis in goats with the new bone volume in BMP-2 group is significantly higher than that in -gal group (P<0.05). At 16th week, the maximum compressive strength and elastic modulus of repairing bone in femoral head of goat in BMP2 treatment group is similar to that of normal cancellous bone and significant higher than that in gal control group(P<0. 05). Conclusion: BMP2 gene modified autologous MSCs / -TCP could enhance the repair of bone defects in aged rats and restore the function of necrotic femoral head in goats.