同种异体骨髓间充质干细胞移植对大鼠急性心肌梗死后Cx43、Cx45mRNA表达的影响

背景：细胞移植可以修复受损的心肌组织，但移植细胞是否和宿主细胞形成有效的电-机械偶联，并引起移植后细胞缝隙连接蛋白重构及心律失常等尚缺乏系统观察。目前只有少数研究发现心肌梗死后缝隙连接蛋白45表达上调，而对于骨髓间充质干细胞移植后缺血区缝隙连接蛋白45的表达尚无报道。 目的：课题组假设通过改变缝隙连接蛋白水平、干预异常的GJ通道，来尝试治疗心肌梗死后心律失常，为此探讨同种异体骨髓间充质干细胞移植对心肌梗死大鼠缝隙连接蛋白43及缝隙连接蛋白45 mRNA表达的影响。 设计、时间及地点：随机对照动物实验，于2008-01/2009-05在广西医科大学实验中心完成。 材料：健康Wistar大鼠180只，随机分为正常对照组、假手术组、心肌梗死组、细胞移植组，45只/组。各组按干预后4，8，12周又分为3个亚组，15只/亚组。另取1月龄健康雄性Wistar大鼠20只，用于分离培养骨髓间充质干细胞。 方法：取传至第3代的大鼠骨髓间充质干细胞，加入10 μmol/L 5-氮胞苷进行诱导，4周后用于移植，在移植前2 h行DAPI标记。心肌梗死组、细胞移植组大鼠建立急性心肌梗死模型，假手术组只穿线不结扎冠状动脉。造模后7 d，细胞移植组将2×1010 L-1骨髓间充质干细胞悬液分多点注射到心肌梗死的边缘区和中心区，心肌梗死组、正常对照组、假手术组均注射等量生理盐水。 主要观察指标：荧光定量PCR法检测缝隙连接蛋白43及缝隙连接蛋白45 mRNA的表达。 结果：①干预后4，8，12周，各组正常区缝隙连接蛋白43、缝隙连接蛋白45 mRNA表达基本相似。②与正常区比较，心肌梗死组、细胞移植组缺血区的缝隙连接蛋白43 mRNA表达均显著减少(P < 0.01)，缝隙连接蛋白45 mRNA表达均显著增加(P < 0.01)。③同一时间点与心肌梗死组比较，细胞移植组缺血区缝隙连接蛋白43 mRNA表达显著增高(P < 0.01)，缝隙连接蛋白45 mRNA表达显著减少(P < 0.01)。 结论：课题创新性证实急性心肌梗死导致心肌缝隙连接蛋白43 mRNA水平下降，缝隙连接蛋白45 mRNA水平升高。5-氮胞苷诱导的同种异体骨髓间充质干细胞移植后，能上调梗死边缘区缝隙连接蛋白43 mRNA的表达，并下调边缘区缝隙连接蛋白45 mRNA的表达。

mRNA expression of connectin 43 and connectin 45 following transplantation of allogenic bone marrow mesenchymal stem cells in rats with acute myocardial infarction

BACKGROUND: Cell transplantation can repair damaged myocardial tissue. However, whether transplanted cells and host cells formed an effective electricity and mechanical couple or whether reconstruction of connexin (Cx) and arrhythmia formed, are still unclear. OBJECTIVE: It is hypothesized that arrhythmia can be treated by changing Cx levels and intervening abnormal GJ channel. Moreover, to explore the effects of bone marrow mesenchyma stem cells (MSCs) on the expression of Cx43 and Cx45 in rats with myocardial infarction. DESIGN, TIME AND SETTING: The randomized controlled animal study was performed at the Experimental Center, Guangxi Medical University from January 2008 to May 2009. MATERIALS: A total of 180 Wistar rats were randomly divided into four groups: normal control, sham operation, myocardial infarction, and MSCs, with 45 animals in each group. Each group was then divided into 3 subgroups (n=15) according to 4 weeks, 8 weeks and 12 weeks post-transplantation. Additional 20 healthy, Wistar rats, aged 1 month, were selected to harvest MSCs. METHODS: The third passage of MSCs was induced by 5-aza like cardiomyocytes for 4 weeks, labeled with DAPI at 2 hours before transplantation. Models of acute myocardial infarction were established in all groups except sham operation group. At day 7 after model preparation, 2×1010/L MSCs were infused into the edge and center of myocardial infarcted region by multipoint injection. Rats in the myocardial infarction group were subjected to an equal volume of saline as well as those in the normal control and sham operation groups. MAIN OUTCOME MEASURES: The mRNA expressions of Cx43, Cx45 were assayed by fluorescence quantitative PCR. RESULTS: The mRNA expression of Cx43 among each groups had no difference at weeks 4, 8 and 12 after intervention in the normal areas. Compared to the normal areas, Cx43 mRNA reduced significantly at ischemic zone in the myocardial infarction group and MSCs group (P < 0.01), with notably increased of Cx45 mRNA expression (P < 0.01). Compared to myocardial infarction group, Cx43 mRNA expression was statistically higher in the MSCs group at the same points (P < 0.01), and the Cx45 mRNA dramatically declined (P < 0.01). CONCLUSION: Acute myocardial infarction reduces the mRNA expression of Cx43 and increases the Cx45 mRNA expression. The exogenous cells transplantation can upturn the mRNA expression of Cx43 in the border-zone of the infarcted area, and down-regulate the Cx45 mRNA expression in the border-zone of the infarcted area.