骨髓间充质干细胞移植对心肌梗死后正常心肌细胞凋亡的影响

Effects of bone marrow mesenchymal stem cell transplantation on apoptosis of normal cardiomyocytes after myocardial infarction

背景:目前的研究显示,骨髓间充质干细胞移植在治疗缺血性心血管疾病中起到了重要的作用,但干细胞移植后改善缺血心肌功能的详细机制尚不明确。目的:观察骨髓间充质干细胞移植对急性心肌梗死后大鼠正常心肌细胞凋亡的影响。设计、时间及地点:随机对照动物实验,于2008-02/08在福建省高血压研究所完成。材料:密度梯度离心法和贴壁筛选法获得SD大鼠骨髓间充质干细胞。2周龄雄性清洁级SD大鼠16只,体质量200～250g,用于制备心肌梗死模型。方法:16只SD大鼠随机区组法分为2组,对照组:结扎冠状动脉前降支,未进行干细胞移植,只在梗死心肌周围注入等量(200μL)的生理盐水;实验组:在心肌梗死1h后,向梗死心肌的周围分4点(200μL)注入同种异体骨髓间充质干细胞1×1011L-1;每组8只。于移植4周后处死动物,取梗死边缘正常心肌组织,TUNEL法检测心肌细胞凋亡形态,并计算心肌细胞凋亡率。主要观察指标:①凋亡心肌细胞的形态变化。②实验组和对照组心肌细胞的凋亡率。结果:①造模后4周,TUNEL检测显示凋亡的心肌细胞核呈深浅不一的深褐色,细胞轮廓清楚,而正常增殖的心肌细胞不被染色。②经显微镜结合计算机显微图像分析系统检测对照组、实验组心肌细胞凋亡率分别是(1.12±0.06)%,(0.81±0.02)%,两者相比差异有显著性意义(P<0.05)。结论:骨髓间充质干细胞移植在一定程度上可以抑制急性心肌梗死后正常心肌细胞凋亡的发生。

BACKGROUND： Present studies have shown that bone marrow mesenchymal stem cell （BMSC） transplantation plays an important role in treatment of ischemic cardiovascular disease. However, the mechanism of improving ischemic myocardial function remains unclear following transplantation. OBJECTIVE： To investigate the effects of BMSC transplantation on apoptosis of rat normal cardiomyocytes after acute myocardial infarction. DESIGN, TIME AND SETTING： The randomized controlled animal study was performed at the Fujian Provincial Hypertension Institute from February to August 2008. MATERIALS： BMSCs were harvested from Sprague Dawley rats by the density gradient centrifugation and adherence screening method. A total of 16 clean male Sprague Dawley rats, aged 2 weeks, weighing 200-250 g, were used to create myocardial infarction models. METHODS： Rats were randomly and equally divided into 2 groups. In the control group, anterior descending of the coronary artery was ligated. 200 μ L of saline was infused into the surrounding regions of infarcted myocardium. In the experimental group 200 μ L of BMSCs （1 × 10^11/L） were injected into the surrounding regions （4 different points） of infarcted myocardium following 1 hour myocardial infarction. Four weeks after the injection, animals were sacrificed to collect normal myocardial tissues surrounding the infarcted regions. The morphology and apoptotic rate of cardiomyocytes were observed by TUNEL. MAIN OUTCOME MEASURES： Morphological changes of apoptotic cardiomyocytes and apoptotic rate of cardiomyocytes in the experimental and control groups were measured. RESULTS： Four weeks after transplantation, TUNEL showed that nuclei of apoptotic cardiomyocytes were brown, with clear outline, and normal cardiomyocytes were not stained. Using the microscope and computer micrograph analytical system, the apoptotic rates of the control and experimental groups were （1.12±0.06）% and （0.81±0.02）% （P 〈 0.05）. CONCLUSION： BMSC transplantation could reduce apoptosis of normal cardiomyocytes following acute myocardial infarction.