血管生成素-1对猪慢性缺血心肌中功能性新生血管增生的促进作用

Promotional effects of angiopoietin-1 on functional neovascularization in a swine model with chronic myocardial ischemia

目的对比血管生成素-1(angiopoietin-1,ANG-1)和血管内皮细胞生长因子(vascular endothelial growth factor,VEGF)在猪慢性心肌缺血模型中的促血管再生效果。方法利用Ameroid血管压缩环建立26只猪慢性心肌缺血研究模型,4周后分成3组:腺病毒携带ANG-1组(Ad ANG-1,n=9),腺病毒携带VEGF组完全恢复灌注术后4周仍然保持缺血状态(Ad VEGF,n=10)和空载体对照组(n=7)。分别在腺病毒介导的基因移植4和12周后,利用荧光微球法测定缺血心肌的局部血流量,并同时进行免疫组化检测。结果基因移植后4周,Ad ANG-1组左心室心肌缺血区的灌注量[(3.25±0.16)m Lmin-1g-1]明显高于Ad VEGF组[(1.09±0.13)m Lmin-1g-1]和对照组[(1.20±0.03)m Lmin-1g-1](P<0.05)。基因移植后12周,Ad ANG-1组和Ad VEGF组的左心室缺血区心肌微血管密度分别为(19.61±1.76)/0.572 mm2心肌组织和(18.17±1.43)/0.572 mm2心肌组织,均明显高于对照组的(13.53±0.92)/0.572 mm2心肌组织(P<0.05)。但就直径50~100μm小动脉密度而言,Ad ANG-1组较空载体对照组显著增加[(1.9±0.4)/0.572 mm2心肌组织切面vs.(0.7±0.2)/0.572 mm2心肌组织切面,P<0.05],而VEGF组与空载体对照组相较则无明显差异。Ad ANG-1组增加了心肌微血管的密度进而提高了局部心肌灌注。结论 VEGF和ANG-1基因转移均可促进血管再生,但只有ANG-1可以促进功能性小血管的再生,从而稳定有效地增加了心肌灌注,并为心功能的改善提供了必要的组织解剖学基础。

Objective To investigate the long-term angiogenic effects of angiopoietin-1（ANG-1） and vascular endothelial growth factor（VEGF） in a swine model with chronic myocardial ischemia.Method Four-weeks after gradual occlusion of the left circumflex coronary artery by Ameroid constrictor,animals were injected with recombinant adenoviral vectors carrying either human ANG-1（Ad ANG-1 group,n= 9）,human VEGF 165（Ad VEGF group,n = 10） or empty vector（n = 7） into the left ventricle free wall supplied by the constricted artery. Four and twelve weeks after the gene transfer mediated by the adenovirus,regional blood flow in ischemic myocardium were respectively measured with fluorescent microsphere while immunohistochemical study were also conducted accordingly. Results Left ventricular perfusion in animals in the Ad ANG-1 group [（3. 25 ± 0. 16） m Lmin-1g-1] were significantly higher than that in the Ad VEGF group [（1. 09 ± 0. 13） m Lmin-1g-1]and empty vector group[（1. 20 ±0. 03） m Lmin-1g-1]4 weeks after gene tranfer（P〈 0. 05）. Microvascular densities in the left ventricles of animals in the Ad ANG-1 group [（19. 61 ± 1. 76）/0. 572 mm2 myocardial tissue] and the Ad VEGF group [（18. 17 ± 1. 43）/0. 572 mm2 myocardial tissue]were significantly higher than animals that received empty vector [（13. 53 ± 0. 92）/0. 572 mm2 myocardial tissue]12 weeks after gene transfer（P 〈0.05）. ANG-1,but not VEGF,contributed to enhanced regional perfusion by increasing arteriolar density [（1.9 ± 0. 4）/0. 572 mm2 myocardial tissue vs.（0. 7 ± 0. 2）/0. 572 mm2 myocardial tissue,P 〈0. 05] of largesized（50-100 μm） arterioles. Conclusions Gene transfer of ANG-1 and VEGF can enhance angiogenesis,but only ANG-1 promotes sustained improvement of ventricular perfusion that expedites recovery of ischemic myocardium via arteriogenesis,which provides histoanatomical prerequisite to expedite recovery of ischemic myocardium.