同种异体骨髓间充质干细胞移植对大鼠心肌梗死后心电生理异常和左室重构的影响

背景:目前干细胞移植修复梗死心肌及改善心脏功能这一作用已被接受,但移植细胞是否和宿主细胞形成有效的电一机械藕联,是否易形成一个有收缩功能的相对电独立体系,并产生移植后严重的恶性室性心律失常等尚缺乏系统观察.目的:观察心肌梗死大鼠行同种异体骨髓间充质干细胞移植后,其心电生理异常及左室重构情况.设计、时间及地点;随机对照动物实验,于2005-12/2008-10在广西医科大学实验中心完成.材料:健康Wistar大鼠120只,随机分为正常对照组、假手术组、盐水对照组、细胞移植组,30只/组.另取1月龄健康Wistar大鼠数只用于抽取骨髓.方法:取体外培养的第3代大鼠骨髓间充质干细胞,加入诱导剂5一氮胞苷使之转化为心肌样细胞,在移植前2 h行DAPI标记.盐水对照组、细胞移植组大鼠结扎冠状动脉左前降支建立心肌梗死模型,假手术组只穿线不结扎冠状动脉.结扎后7 d,细胞移植组将2×10L<'-1>骨髓间充质干细胞分多点注射到心肌梗死的边缘区和中心区,其余3组注射等量生理盐水.主要观察指标:体表ECG及心电生理检测,UCG检测左室功能,左室病理检查测定梗死面积,荧光显微镜下观察DAPI标记的供体细胞迁移、分布情况.结果:骨髓间充质干细胞体外诱导可分化为自发搏动的心肌样细胞,表达心肌特异性肌钙蛋白T,并形成肌丝结构.细胞移植后4,8,12周与盐水对照组比较,细胞移植组PR间期、QRS时限和心室有效不应期缩短,而室颤阈值增加(P<0.05);左室收缩末期内径减小,左室射血分数、左室短轴缩短率均显著增加(P<0.05);移植后8,12周心肌梗死面积明显缩小(P<0.05).移植后4周,在荧光显微镜下梗死区可见DAPI标记带蓝色荧光的移植骨髓间充质干细胞细胞核,至12周仍然存在,但随移植时间延长荧光强度逐渐减弱.结论:骨髓间充质干细胞具有分化为心肌样细胞的可塑性,同种异体骨髓间充质干细胞移植可有效改善心肌梗死后的心电生理异常和左室重构.

Effects of allogenic bone marrow mesenchymal stem cell transplantation on electrophysiological abnormality and left ventricular remodeling in rats with myocardial infarction

BACKGROUND: Stem cell transplantation in repairing infarct myocardium and in improving cardiac function has been widely accepted. However, whether transplanted cells and host cells formed an effective electricity and mechanical couple, whether a relevant independent electrical system with contractile function formed or whether severe malignant ventricular arrhythmia formed, are still unclear.OBJECTIVE: To investigate electrophysiological abnormaltiy and left ventricular remodeling in rats with myocardial infarction following allogenic bone marrow mesenchymal stem cell (BMSC) transplantation.DESIGN, TIME AND SETTING: The randomized controlled animal study was performed at the Experimental Center, Guangxi Medical University from December 2005 to October 2008.MATERIALS: A total of 120 healthy Wistar rats were equally randomized into normal control, sham operation, saline control and cell transplantation groups. Healthy Wister rats aged 1 month were selected to harvest bone marrow.METHODS: At the third passage, rat BMSCs were collected and treated with 5-aza, and differentiated into cerdiomyocytes.BMSCs were labeled with DAPI at 2 hours before transplantation. In the saline control and cell transplantation groups, rat models of myocardial infarction were established by ligating the left anterior descending coronary artery. In the sham operation group, the coronary artery was not ligated, but only braid. At 7 days following ligation, BMSCs in the cell transplantation group at 2×10-1/L were infused into the edge and center of myocardial infarct region by multipoint injection. Rats in the other three groups were subjected to an equal volume of saline.MAIN OUTCOME MEASURES: Electrocardiogram and cardiac electrophysiology were performed. Ultrasonic cardiography was used to detect left ventricular function. Infarct size was determined. DAPl-labeled donor cell migration and distribution was observed with a fluorescence microscope.RESULTS: BMSCs could differentiate into cardiacmuscle cell-like cells which were capable of pulsing spontaneously, expressing cardiactoponin T and forming myofilament in vitro. Compared with the saline control group, PR interval, QRS duration and ventdcular effective refractory period shortened, ventricular fibrillation threshold increased at 4, 8 and 12 weeks (P < 0.05); left ventricular internal diameter at end-systole reduced, and left ventricular ejection fraction and shortening traction was significantly increased (P< 0.05). At 8 and 12 weeks, infarct size was significantly smaller (P < 0.05). At 4 weeks, DAPl-labeled BMSCs could be seen under the fluorescence microscope, and still could he detected at 12 weeks. However, the fluorescence became weak with prolonged time.CONCLUSION: BMSCs have the plasticity of differentiating into cardiac muscle cell-like cells, which can modulate theelectrophysiological abnormality and left ventricular remodeling following myocardial infarction.