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

Abstract

To investigate the influence of vascular endothelial growth factor (VEGF) 165 gene transfection on the repair of bone defect. 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 microvessel 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). 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. 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.