下肢缺血性血管新生的血管内皮生长因子受体-2超声分子成像研究

Ultrasound molecular imaging of endothelial vascular endothelial growth factor recptor-2 expression during hind-limb ischemia-mediated angiogensis

目的 探讨应用携血管内皮生长因子受体-2（vascular endothelial growth factor receptor-2,VEGFR-2）分子探针的超声分子成像评价小鼠下肢缺血性血管新生的可行性.方法 12只实验小鼠结扎一侧下肢股动脉制备下肢缺血模型,另一侧下肢作为对照组.术后第7d所有小鼠均随机先后间隔30 min经尾静脉注入携抗小鼠VEGFR-2单抗的靶向微泡（MBVEGFR-2）和携同型抗体的对照微泡（MBIso）,并于8min后行对比超声检查,测量双侧下肢的显影强度（video intensity,VI）,最后处死小鼠取下肢骨骼肌行免疫组化检查.结果 对比超声图像显示MBVEGFR-2组缺血下肢可见明显的超声显影,VI值高达（25.6±4.3）U,而在MBIso组缺血下肢仅可见轻度的超声显影,VI值为（6.7±1.6）U,两者之间的差异有统计学意义（P＜0.05）.但无论MBVEGFR-2还是MBISO,缺血下肢VI值均显著高于非缺血下肢VI值（P＜0.05）.两组微泡在非缺血下肢的VI值差异无统计学意义（P＞0.05）.免疫组化检查显示缺血下肢血管内皮表达大量的VEGFR-2,而非缺血下肢未见VEGFR 2表达.结论 应用VEGFR-2分子探针的超声分子成像可有效评价下肢缺血性血管新生,将为评价治疗性或相关的血管新生提供新的技术手段.

Objective To explore the feasibility of evaluation of mice hind limb ischemia-mediated angiogenesis with ultrasound molecular imaging using molecular probes targeted to angiogenesis endothelial marker VEGFR-2.Methods A mice model of unilateral hind-limb ischemia was induced by femoral artery excision in 12 experimental mice.Ultrasound molecular imaging of the ischemia and contralateral non-ischemia hind-limbs was performed in all mice on day 7 after surgery at 8 minutes after intravenous injection of either VEGFR-2 targeting microbubbles or isotype control microbubbles in random with 30 min interval,and the video intensity （VI） was measured.Following ultrasound imaging,the hind-limb was harvested for immunohistochemical analysis.Results As expected,VI in the ischemia hind-limb was significantly higher （P ＜0.05） for MBvEGFR-2 [（25.6 ± 4.3）U] as compared with MBIso[（6.7 ± 1.6）U].However,the ultrasound signal in the non-ischemia hind-limb was low for both MBvEGFR-2 [4.4 ± 1.5）U] and MBIso [（4.6 ± 1.6）U].A marked endothelial VEGFR-2 expression in ischemia hind-limb was confirmed by immunohistochemistry.Conclusions Ultrasound molecular imaging using molecular probes targeted to angiogenesis endothelial VEGFR-2 can effectively evaluate ischemia-mediated angiogenesis.