低幅高频振动促进骨质疏松性骨折愈合的血管新生机制

Bone fracture, especially osteoporotic fracture, has become a major health issue due to its increase in morbidity, mortality and the financial burden of medical care. Our previous studies confirmed low-magnitude high-frequency vibration (LMHFV) (magnitude=0.3g, frequency=35Hz), providing non-invasive, systemic mechanical stimulation, can promote both normal and osteoporotic fracture healing in rats. However, the mechanism of its positive osteogenic effect is still unclear.Based on previous studies, we hypothesize that LMHFV can stimulate the angiogenesis at the fracture site in both normal and osteoporotic rats with different extent, hence to accelerate the healing process.With compared to the control groups, the effect of LMHFV on angiogenesis and osteogenesis will be assessed in normal and osteoporotic fractures of rats. At 1, 2, 4 and 8 weeks post-treatment, X-ray, microCT-based microangiography, real-time PCR and immunohistochemistry will be performed to assess the osteogenic and angiogenic outcomes at the fracture site. This will be the first study to look into the mechanism of LMHFV on fracture healing in angiogenesis quantitatively. Meanwhile, this may provide evidences to explain the impaired fracture healing in osteoporotic bones. The findings will consolidate the application of LMHFV for routine treatment of fracture healing.

鉴于发病率、死亡率及医疗财政负担的不断增加，骨折，尤其是骨质疏松性骨折，成为当今日益严峻的社会问题。我们的前期研究表明低幅高频振动（low-magnitude high-frequency vibration, LMHFV）（振幅0.3g，频率35Hz）可促进正常骨折与骨质疏松性骨折的愈合，但其正性成骨作用机制尚不明了。基于既往研究，我们推测LMHFV可不同程度地增加正常和骨质疏松性骨折端的血管新生，从而促进愈合。本课题拟通过与对照组比较，观察LMHFV治疗正常和骨质疏松性大鼠骨折端成血管与成骨状况。治疗期分为1、2、4、8周，采用X线、microCT微血管造影术、Real-time PCR、免疫组化等技术定性、定量评估骨折端骨组织与新生血管情况。本实验首次探讨了LMHFV对骨折端血管新生的影响，并试图揭示骨质疏松性骨折愈合延迟的机制，为推广该新型治疗手段提供理论基础。

骨质疏松性骨折的愈合能力较正常人降低。我们的前期研究证明低幅高频振动（LMHFV）可以促进正常及骨质疏松性骨折的愈合。鉴于血管新生是骨折愈合的重要因素，本课题主要探讨LMHFV是否是通过促进骨折段血管新生来增强骨愈合能力，并研究骨质疏松性骨折延迟愈合的可能机制。本实验以9月龄卵巢切除（OVX）与假切除（Sham）的SD大鼠为研究对象，构建闭合性股骨干横断骨折模型，平均随机分成LMHFV治疗组（Sham-V, OVX-V）与对照组（Sham-C, OVX-C）。每周记录测量骨痂形成情况。在治疗第2、4、8周，大鼠的后肢采取Microfil灌注，测量分析骨折段新生血管及骨痂定性定量数据。免疫组化技术用来分析骨痂内血管内皮生长因子（VEGF）的表达量。MicroCT血管造影术的结果显示：振动组骨折段新生血管量显著高于对照组，OVX组的血管新生能力较Sham组弱。骨生成的结果变化（X线、MicroCT）与血管新生趋于一致。免疫组化分析也显示在骨折愈合早期，振动组VEGF表达较对照组上调。由此证明，骨质疏松性骨折的骨折段血管新生能力较正常骨质减弱。LMHFV可以促进骨折段血管新生，从而增强骨折愈合能力。该研究有助于进一步揭示血管新生在LMHFV促进骨折愈合过程中所起的作用，并发现骨质疏松将损害血管新生能力从而延缓愈合。未来LMHFV在临床上促进骨折、伤口愈合以及治疗某些血管疾患可能存在巨大的应用潜力。