促血管生成素-1在心肌梗死大鼠脐血干细胞移植促进血管新生中作用

Effects of angiopoietin-1 on angiogenesis in umbilical cord blood stem cell transplantation in rats with myocardial infarction

目的探讨人脐血干细胞移植于心肌梗死大鼠后是否通过促血管生成素-1(Ang-1)介导血管再生。方法雄性Sprague-Dawley大鼠40只,随机分为3组,经手术干预后死亡10只,假手术组(9只)、对照组(11只)及移植组(10只)。假手术组仅开胸,冠状动脉前降支(LAD)挂线不结扎;对照组结扎LAD造成心肌梗死后,经静脉注射生理盐水;移植组结扎LAD造成心肌梗死后,经静脉注射等量干细胞悬液,术后4周处死大鼠,留取心脏左室组织。免疫组化染色人特异性心肌肌钙蛋白T(c Tn T)、人主要组织相容性复合体(hMHC)、VⅢ因子、Ang-1蛋白,RT-PCR检测心肌组织Ang-1的mRNA表达水平。结果在移植组可见胞浆呈褐色的cTnT和hMHC阳性细胞。与假手术组比较,对照组和移植组Ang-1免疫组化染色积分光密度(IOD)值明显增加,差异有统计学意义(P<0.05);与对照组相比,移植组Ang-1免疫组化染色IOD值明显增加,差异有统计学意义(P<0.01)。与假手术组比较,对照组和移植组Ang-1 mRNA的相对表达明显增加,同时与对照组相比,移植组Ang-1 mRNA相对表达也明显增加,差异有统计学意义(P均<0.01)。Ⅷ因子为心肌毛细血管密度测定指标,移植组梗死周边区毛细血管密度较对照组明显增加,而假手术组无明显变化。结论经静脉移植人脐血干细胞能在心肌梗死大鼠梗死心肌存活并表达心肌特异性收缩蛋白,同时心肌毛细血管密度增加,其机制可能为Ang-1表达增加进而促进血管新生。

Objective To discuss whether human umbilical cord blood stem cells（UCBSC） inducing angiogenesis through angiopoietin-1（Ang-1） in rats with myocardial infarction after the transplantation of human UCBSC. Methods Male SD rats（n=40） were randomly divided into sham-operation group（n=9）, control group（n=11） and transplantation group（n=10）. The sham-operation group was only give treatment of chest-open without ligation of anterior descending coronary artery, control group was given intravenous injection of normal saline solution after the ligation for inducing myocardial infarction, and transplantation group was given intravenous injection of human UCBSC suspension after the ligation for inducing myocardial infarction. After 4 w, the rats were killed for collecting left ventricular tissues. The human-specific cardiac troponin T（c Tn T）, human major histocompatibility complex（h MHC）, VIII factor and Ang-1 were stained by using immunohistochemistry technique, and expression of Ang-1 m RNA was detected by using reverse transcription-polymerase chain reaction（RT-PCR）. Results There were positive cells of c Tn T and h MHC with brown cytoplasma observed in transplantation group. Compared with sham-operation group, integral optical density（IOD） of Ang-1 increased significantly in control group and transplantation group（P〈0.05）. Compared with control group, IOD of Ang-1 increased significantly in transplantation group（P〈0.01）. Compared with sham-operation group, the expression of Ang-1 m RNA increased significantly in control group and transplantation group, and compared with control group, the expression of Ang-1 m RNA increased significantly in transplantation group（all P〈0.05）. VIII factor, as the index for detecting myocardial capillary density, increased significantly in transplantation group compared with control group, and had no significant changes in sham-operation group. Conclusion The intravenous transplanted human UCBSC can survive and express myocardial-specific contractile protein, and at the same time myocardial capillary density increases at cardiac infarction area in rats with myocardial infarction, and the mechanism maybe related to that the increase of Ang-1 expression can promote angiogenesis.