Objective To explore the effect of electroporation mediated gene therapy on bone mineral density and strength of new-formed bone in mandibular distraction gap, so as to enhance the osteogenesis and shorten the distraction term. Methods New-Zeland rabbits were employed. The distraction began after 3 days of latency period at the rate of 0. 8 mm per day for 7 days. After distraction, the rabbits were randomly divided into 5 groups to receive injection in the distraction gap with recombinant plasmid 2 μg(0. 1μg/μl)pIRES-hVEGF165-hBMP2 in group A, with recombinant plasmid pIRES-hBMP2 in group B, with recombinant plasmid pIRES-hVEGF165 in group C, with pIRES in group D, and with normal saline (NS) in group E. After injection, electroporation was performed in all the groups. After 1 week, 2 weeks, 4 weeks and 8 weeks of consolidation, all the animals underwent X-ray and quantitative computed tomography (QCT). The new-formed bone in distraction gap was selected as regions of interest (ROI) to measure the bone mineral density( BMD). Then the rabbits were sacrificed and the new-formed bone samples were harvested to detect 3-point crushing strength. Results BMD of newly formed bone in group A, B and C was markedly higher than that in group D and E (P < 0. 01 ). After 2 weeks of consolidation, BMD in group A was much higher than that in the other groups, but there was no difference between group B and C. After 4 weeks of consolidation, BMD in group A and B was markedly higher than that in group C, D and E ( P < 0. 01 ). After 8 weeks of consolidation, BMD in group A was markedly higher than that in the other groups. While the BMD was not significantly different between group B and C, but the BMD in group B and C was higher than that in group D and E ( P < 0. 01 ). After 4 weeks of consolidation, the 3-point crushing strength of newly formed bone in group A was markedly higher than that in group B,C, D and E ( P < 0. 01 ) , which was still the same after 8 weeks of consolidation. And the crushing strength in group B was higher than that in group C, D and E ( P < 0.05 ). Conclusions Electroporation-mediated transfection of recombinant plasmid pIRES-hVEGF165-hBMP2 could greatly enhance osteogenesis and calcification. A combination of VECF and BMP may promote osteogenesis and angiogenesis simultaneously, so as to magnify the effect of each growth factor, resulting a synergetic effect.%目的 探索电穿孔介导的基因治疗对下颌骨DO过程中牵引间隙新生骨密度与强度的影响,从而为促进下颌骨DO新骨生成,缩短牵引周期,减少并发症提供新思路.方法 以新西兰大白兔为实验动物模型,于术后3 d开始下颌骨牵引,每天0.8 mm,连续牵引7 d后,将实验动物分为5组.A组:在牵引区注射2 μg(O.1μg/μl)重组质粒pIRES-hVEGF165-hBMP2;B组:在牵引区注射2 μg(0.1μg/μl)重组质粒pIRES-hBMP2;C组:在牵引区注射2 μg(0.1μg/μl)重组质粒pIRES-hVEGF165;D组:在牵引区注射2 μg(0.1μg/μl)空质粒pIRES;E组:在牵引区注射相同剂量的生理盐水.5组实验动物均施加电穿孔刺激.各组分别于固定期第1、2、4、8周行X线及QCT检查.选整个牵张间隙新生骨痂部分为兴趣区,测定骨密度.然后处死动物.取材测量牵引区新生骨的三点抗压强度.结果 A、B、C组新生骨痂密度各时相点新生骨痂密度明显高于D、E组(P<0.01).固定2周,A组明显高于各组,但B、c组间比较差异无统计学意义.固定4周,A、B组明显高于C、D、E组(P<0.01).固定8周A组明显高于B、c、D、E组(P<0.01).B、C组间比较差异无统计学意义,但高于D、E组(P<0.01).固定4周,A组新生骨的三点抗压强度明显高于B、C、D、E组(P<0.01).固定8周,A组仍明显高于各组(P<0.01),且B组也明显高于c、D、E组(P<0.05).结论 电脉冲介导的pIRES-hVEGF165-hBMP2重组质粒体内转染可使牵引区获得较满意的骨再生和骨化成熟进程,其新骨骨化、改建过程均超过对照组.提示联合应用BMP与VEGF,可能会实现成骨与血供的联合重建,并且使单一生长因子的效应放大,使骨愈合的速度加快.
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