血管内皮细胞生长因子165基因转染对兔骨缺损修复的影响

目的 构建pcDNA3．1-血管内皮细胞生长因子（VEGF）165质粒,观察其对兔骨缺损修复的影响。方法构建成重组真核表达质粒pcDNA3．1-VEGF165;采用30只新西兰大白兔,制备双侧桡骨骨缺损模型,实验组以体积等大的明胶海绵置于创腔,局部直接注射稀释的质粒液200ng;对照组以同量生理盐水代替质粒液,同法处理。于术后1、2、4、6、8和12周行X线照片后获取标本,观察缺损局部组织修复及新生血管并计算微血管密度（MVD）。结果pcDNA3．1-VEGF165质粒构建成功,测序正确。术后X线：1周时两组无明显差别,实验组2周骨痂形成、骨质修复,12周时骨质已正常,对照组表现为修复迟缓;HE染色：实验组2周大量新生血管形成、通血,4周成骨细胞大量增殖、骨小梁形成,12周骨皮质改建完成,骨髓腔再通;对照组经历过程类似,但相对时间延迟,12周时骨髓腔及皮质改建尚未完成。2周时对照组及实验组MVD分别为56．1±6．1、69．1±5．4,均较1周时42．2±6．4、47．0±7．5时增加,组间及组内间差异有统计学意义（t=8．0347,P=0．0000）。结论骨缺损局部直接应用PcDNA3．1-VEGF165质粒液后,可表达并上调VEGF165,具有促进局部微血管形成、加快骨缺损修复的作用。

Effect of vascular endothelial growth factor 165 gene transfection on repair of bone defect: experiment with rabbits

OBJECTIVE: To investigate the influence of vascular endothelial growth factor (VEGF) 165 gene transfection on the repair of bone defect. METHODS: 38 New Zealand rabbits underwent resection of a segment 1 cm in length in bilateral radii filled with absorbable gelatin sponge. Dilated solution of the plasmid pcDNA3.1/VEGF165 was injected into the bone defect of one side and normal saline was injected into the contralateral bone defect. 1, 2, 4, 6, 8, and 12 weeks later X ray examination was conducted to observe the repair of bone defect, and then 5 rabbits were killed at each time points to take out the bone defects. HE staining was used to observe the bone repair. The levels of mcrovessel density (MVD) 1 and 2 weeks after the operation were observed. RT-PCR was used to detect the mRNA expression of VEGF in the bone defect. Based on the results of RT-PCR the tissue mRNA expression of VEGF65 was detected by real-time quantitative polymerase chain reaction (RQ-PCR). RESULTS: X-ray examination showed that there was no significant difference in the wound healing between the two group 1 week after the operation in all rabbits. Some callus could be seen in the experimental group 2 weeks after. Twelve weeks after the operation the reconstruction of bone cortex was completed. Similar process occurred in the control sides but more lately. The MVD level 7 days after of the experimental group was 47.0 +/- 7.5, significantly higher than that of the control group (42.2 +/- 6.4, t = 2.4519, P = 0.0179), and the MVD level 14 days after of the experiment group was 69.1 +/- 5.4, significantly higher than that of the control group (56.1 +/- 6.1, t = 8.0347, P = 0.0000). In the experimental group the mRNA expression amounts of VEGF165 could be found 1 week after, gradually increased and peaked 3 weeks after, then decreased, and became stable 6 weeks after. The mRNA expression amounts of VEGF165 in the control group were lower than those of the experimental group. CONCLUSION: Local application of PcDNA3.1/VEGF(165) vector promotes the expression of VEGF165, and enhances the quantity of the angiogenesis, extra cellular matrix and healing of bone defect.