Effect of vascular endothelial growth factor 165 gene transfection on bone defects and its mRNA expression in rabbits.

BACKGROUND: Gene therapy has been a hot spot in repair of bone defects in recent years. This study aimed to construct a recombinant plasmid pcDNA3.1-VEGF(165), and to observe the effect of vascular endothelial growth factor 165 (VEGF(165)) gene therapy on bone defects in rabbits. METHODS: Total RNA was extracted from rabbit bone tissues. VEGF(165) cDNA fragment was prepared by reverse transcription and the gene was cloned by polymerase chain reaction (PCR). Plasmid pMD18-T/VEGF(165) combined with pcDNA3.1 was cloned to reconstruct pcDNA3.1-VEGF(165) plasmid. Thirty New Zealand white rabbits weighing (2.50 +/- 0.13) kg were used to establish models of bone defects (1 cm in length) of the bilateral radii. The bone defects were repaired with absorbable gelatin sponge. After the operation, physiological sodium chloride solution was injected into the injured site in one of the forelegs of the rabbits as the control group, and pcDNA3.1-VEGF(165) plasmid (0.2 ml, 200 ng) was injected into the opposite foreleg as the experiment groups. At weeks 1, 2, 4, 6, 8, and 12 after the treatments, the bones were examined by X-ray, and the specimens of the bone defects were collected, stained with HE, and observed under a light microscope. The expression of VEGF(165) mRNA was examined by real-time quantitative polymerase chain reaction (RQ-PCR). RESULTS: The pcDNA3.1-VEGF(165) plasmid with a correct sequence was constructed successfully. Postoperative X-ray found no difference between the two groups at week 1. In the experiment group, callus and synostosis were observed after 2 weeks, and osteosis structure was normal at week 12; these phenomena occurred much later in the control group. In the experiment group, HE staining showed a large amount of newly formed blood vessels after 2 weeks, a number of bone trabeculae with osteoblasts proliferation at 4 weeks, and fresh bone cortex and reformed medullary cavity at 12 weeks; whereas in the control group these structures formed in later phases. The VEGF(165) mRNA in the experiment group was expressed at a low level at week 1, reached the peak at weeks 3, and then decreased to a normal level after 6 weeks. CONCLUSIONS: Local use of pcDNA3.1-VEGF(165) plasmid at bone defects can upregulate the expression of VEGF(165) and accelerate the formation of capillaries and the repair of bone defects. Angiogenesis and osteogenesis can be promoted by a combination of pcDNA3.1-VEGF(165) and gelatin sponge.

[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 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). 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.

[Correlation analysis on the malocclusion and articulation of skeletal angle III malocclusion in mixed dentition].

OBJECTIVE: To investigate the effects of skeletal Class III malocclusion in mixed dentition on speech articulation and to look for which factors lead to the speech errors. METHODS: Thirty-eight children with skeletal Angle Ill malocclusion in mixed dentition were selected as a sample group and 40 children with normal occlusion in mixed dentition as a control group. Two phoneticians evaluated their articulations and wrote down error phonemes respectively. The correlation analysis was undertaken between the number of errors and the measurements of patients' cephalometry. RESULTS: The number of errors were correlated significantly with overbite, UI-LI, OBJ (OB+OJ) and TD-PW. CONCLUSION: There is articulatory malfunction in the majority of skeletal Angle III malocclusion patients in mixed dentition. Articulatory malfunction is related to the position of incisors and the tongue.

[The effect of pcDNA3.1-vEGF165 recombined vector on wound healing and the expression of collagen type I, III mRNA in wounded tissue].

OBJECTIVE: To examine the effect of pcDNA3.1-VEGF165 vector to the angiogoiesis, expression of collagen type I and type III mRNA in soft tissue injury model. METHODS: Thirty two Sprague-Daulay rats,weighted (180 +/- 20) g, were made tissue injury in the bilateral of vertebral region. Round wound (diameter 12 mm) was made by perforex on the back, removed the skin and 2 mm muscle, one side was experimental group by random and the other as control. The wound was done with sodium chloride (0.2 ml) in the control group, with the recombinant VEGF165 vector (0.2 ml, 200 mg) in the experimental group. The wound healing and other general state of health was observed after the operation. The specimens were obtained at 3,5, 7,14 and 30 days after injury. Draw the materials from the rats at the same time, all samples were divided into two parts. one ( > 0.1 g) was conserved in refrigerator at - 80 degrees C, which was extracted total RNA by TRIZOL, design the primer of rat's collagen type I and type III, RT-PCR analysis indicated that collagen type I, III. The other was fixed by 10% formalin. Examine wound healing of local tissue and count it' s MVD by HE staining. RESULTS: All the rabbits were well alive, no death or infection. Wound healing time was shorter than the control one (14.2, 17.4 d). Inflammatory cell infiltrate, cellula intersitialis, fibroblast, collagen and the density of angiogenesis were more in the experimental group than in the control one. The MVD was significant difference between the two groups at 1, 2 weeks are 63.38 +/- 9.20, 52.72 +/- 7.06 and 76.64 +/- 12.27, 66.84 +/- 9.82 (P < 0.05). The expression of collagen type I , III mRNA was found in the third day, the peak was in the second week and then degression. The collagen type I , III mRNA and beta-actin specificitic belt were found and its initial template volume different, the results was trend of RT-PCR obtained. CONCLUSIONS: The local application of pcDNA3.1-VEGF165 can enhance the expression of collagen type I, III mRNA, enhance angiogenesis and extra cellular matrix, both of which can shorten healing time of tissue injury.