携抗ICAM-1靶向微泡定向转染Ang-1基因治疗急性心肌梗死的实验研究

Targeted transfection of Ang-1 gene via microbubbles carrying ICAM-1 antibody to acute myocardial infarction

目的探讨携抗ICAM-1的靶向微泡定向转染基因至心肌细胞的能力及其作为新型载体治疗急性心肌梗死的可行性。方法37只家兔制备急性心肌梗死模型。3只经耳缘静脉注射携ICAM-1抗体靶向微泡，心肌组织冷冻切片后观察其对受损血管内皮的吸附。余34只兔随机分为3组：IM组（心肌注射Ang-1基因组）、ICAM-1组（注射携抗ICAM-1靶向微泡＋Ang-1基因组）、对照组（空白对照），于基因转染前后分别行常规超声心动图检查，处死后取心肌组织及ICAM-1组家兔肝、肾组织行RT—PCR及Western—Blot分别检测目的基因及蛋白表达；免疫组化Ⅷ因子染色检测其新生毛细血管密度。结果IM组、ICAM-1组基因转染后2周左室射血分数（LVEF）均较转染前显著提高（P〈0．05），其中IM组及ICAM-1组之间差异无统计学意义；IM组及ICAM-1组行RT-PCR及Western-Blot均可检测出目的基因及蛋白表达，且两组之间表达量差异无统计学意义；对照组及IcAM-1组肝肾组织未见明显Ang-1tuRNA及蛋白表达。心肌组织Ⅷ因子染色后高倍镜下显示IM组及ICAM-1组均可见大量新生毛细血管，其中相对于ICAM-1组，IM组新生毛细血管计数更高。结论携抗ICAM-1的靶向微泡可定向转染Ang-1基因至心肌细胞，其转染效率与目前认为最高效的心肌内注射基因的转染效率近似，可作为新型靶向载体定向转染血管新生基因，对急性心肌梗死具有治疗作用。

Objective To explore the capability of Ang-1 gene delivery to acute myocardial infarction using targeted microbubbles carrying ICAM-1 antibody. Methods Thirty-seven rabbits＇ left circumfles branch coronary arteries were ligated for models. Three rabbits were injected with microbubbles carrying ICAM-1 to detect the ability of targeting. Thirty-four rabbit models were divided into 3 groups randomly as follow ： IM group （ n = 12, accept direct intramuscular injection）, ICAM-1 group （ n = 12, accept intravenous injection of targeted microbubbles and Ang-1） and control group （n = 10, without any treatment）. Ultrasonography were executed on all animals before and 2 weeks after the treatment. All rabbits were killed after 2 weeks and examined for Ang-1 mRNA and protein by RT-PCR and Western-Blot respectively. Microvessel density （MVD） counting of infracted myocardium, observed by factor Ⅷ immunochemical staining,was performed to value the proangiogenesis effect of Ang-1 delivered by targeted microbubbles carrying ICAM-1 antibody. The liver and the kidney in ICAM-1 group were taken to assess the systemic delivery. Results IM and ICAM-1 group showed significantly improvement in the ejection fraction （ P 0.05） while control group did not. Ang-1 mRNA and protein could be detected in IM and ICAM-1 group; however,the expression between the two groups showed no siginificant difference. None of the control animals showed Ang-1 expression. Compared with ICAM-1 group,the MVD was greater in IM group. Ang- 1 was not detected either in liver or in kidney in ICAM-1 group. Conchtsions Targeted microbubbles carrying ICAM-1 antibody can deliver Ang-1 gene to ischemic myocardium directly. Meanwhile, it＇s as effective as IM injections besides the greater angiogenesis effect. This strategy improves the perfusion of acute myocardial infarction and the function of heart.