Runt相关基因2修饰的骨髓间充质干细胞促进兔下颌骨牵张成骨的研究

Mesenchymal stem cells modified with Runt-related transcription factor 2 promote bone regeneration in rabbit mandibular distraction osteogenesis

目的探讨Runt相关基因2(Runx2)修饰的自体骨髓间充质干细胞(MSCs)促进兔下颌牵张成骨新骨形成的可行性。方法将48只成年雄性新西兰大白兔随机分为3组:A组为Runx2重组质粒组,B组为不含Runx2重组质粒组,C组为生理盐水对照组。建立兔下颌牵张成骨模型;于牵张的第5天,A组兔牵张间隙内注射转染重组质粒adv-h Runx2-gfp的自体骨髓MSCs;B组注射转染adv-gfp质粒的自体骨髓MSCs;C组注射同体积生理盐水。在牵张结束后第8周处死所有动物,进行大体、影像学、组织学观察和三点弯曲测试。结果 CT平扫及组织学结果表明,A组牵张间隙内新骨形成和骨痂密度均明显高于B、C组;双能X线及三点弯曲测试表明,A组牵张间隙内新生骨组织密度、新生骨矿物质含量及最大载荷均高于B、C组(P<0.01)。结论基于MSCs的Runx2体外基因治疗可有效地促进牵张成骨新骨形成,从而缩短固定期,为临床颅颌面骨缺损的重建提供一个极具价值的修复策略。

Objective This work investigated mesenchymal stem cells（MSCs） modified with Runt-related transcription factor 2（Runx2） therapy for bone regeneration in rabbit mandibular distraction osteogenesis. Methods Forty-eight New Zealand mature white rabbits were randomly divided into three groups after the rabbit model of mandibular distraction osteogenesis was established： reconstruction plasmid modified with Runx2（group A）, plasmid without Runx2（group B）, and the same dose of saline as control（group C）. At the fifth day of distraction phase, MSCs with reconstruction plasmid modified with adv-h Runx2-gfp were injected into the distraction gap of group A. MSCs with reconstruction plasmid modified with adv-gfp was injected into the distraction gap of group B, whereas group C was injected with the same dose of saline. At 8 weeks after injection, all animals were sacrificed, and the distracted mandibles were harvested. The general imaging histological observation and three-point bending test were used for evaluation. Results CT plain scan and histological analysis confirmed that the amount of new bone forming in the distraction gap of group A was significantly higher than those in groups B and C. Dual-energy X ray and three-point bending test results also showed that the bone mineral density, bone mineral content, and maximum load of the distraction gap of group A were significantly higher than those of groups B and C（P〈0.01）. Conclusion Runx2-ex vivo gene therapy based on MSCs can effectively promote the bone regeneration in rabbit mandibular distraction osteogenesis and shorten the stationary phase. Therefore, reconstruction of craniofacial fracture would be a valuable strategy.