经冠状动脉移植自体骨髓单个核细胞治疗犬急性心肌梗死

Autologous bone marrow mononuclear cells for treating canine acute myocardial infarction through coronary artery transplantation

背景:近年的研究表明,细胞移植可以修复受损的心肌组织,促进缺血区域新生血管的形成,改善缺血心肌的灌注和收缩功能。目的:观察自体骨髓单个核细胞经冠状动脉移植至犬心肌梗死模型后在体内的分化及对心功能的影响。设计、时间及地点:随机对照动物实验,于2006-09/2008-04在天津泰达国际心血管病医院动物实验室完成。材料:成年杂种犬16只,体质量15～25kg,通过结扎冠状动脉前降支中段建立急性心肌梗死模型。方法:16只杂种犬投币法随机分为移植组(n=10)和对照组(n=6),移植组于心肌梗死后2h经冠状动脉内移植CM-DiI标记的骨髓单个核细胞;对照组注射等量生理盐水。冠状动脉结扎后2h及6周时行超声心动图检查,移植后6周处死所有动物于梗死区及其邻近部位取材。主要观察指标:①心肌梗死后6周两组心功能指标比较。②荧光显微镜下观察骨髓单个核细胞在心肌组织中的分化情况。③透射电镜观察移植组梗死区心肌组织的变化。结果:纳入杂种犬16只,全部存活。左前降支结扎2h后可见结扎点远端心肌组织变紫,室壁活动减弱,心电图出现ST段弓背样抬高。①对照组心肌梗死后6周和心肌梗死后2h相比各项指标均无显著改善(P>0.05)。移植组术后6周时左心室射血分数、左心室收缩期末内径及左心室短轴缩短率均较心肌梗死后2h有明显改善(P<0.01),其中左心室射血分数与对照组相比亦有明显改善(P<0.05),移植组射血分数较对照组提高7%左右。②荧光显微镜下可见移植组自体骨髓单个核细胞经冠状动脉移植后可分布于梗死区及梗死周边区,并表达肌球蛋白重链;正常心肌组织及对照组心肌组织内未见移植细胞。③透射电镜下可见移植组分化完全的血管内皮细胞及类心肌样细胞。结论:骨髓单个核细胞可在梗死区梗死周边区存活并逐渐分化成心肌样细胞,促进缺血心肌血管新生,改善心功能。

BACKGROUND： Cell transplantation can repair damaged myocardial tissue, promote formation of new vessels in ischemic region, and improve perfusion and systolic function of ischemic myocardium. OBJECTIVE： To study differentiation of autologous bone marrow mononuclear cells （BM-MNCs） and its effects on cardiac function through coronary artery transplantation in dog myocardial infarction models. DESIGN, TIME AND SETTING： The randomized controlled animal study was conducted at the Animal Laboratory of TEDA International Cardiovascular Hospital from September 2006 to April 2008. MATERIALS： Sixteen hybrid canines weighing 15 25 kg were used to establish acute myocardial infarction models through ligating the middle piece of anterior descending coronary artery. METHODS： Sixteen hybrid canines were randomly divided into the cell transplantation group（n=10） and the control group （n=6）. BM-MNCs labeled with CM-Dil previously were transplanted into myocardium via coronary artery 2 hours after acute myocardial infarction in the cell transplantation group and the saline in the control group. Cardiac function was evaluated 2 hours and 6 weeks after transplantation by echocardiography. All animals were sacrificed 6 weeks following transplantation at infarct region and surrounding the infarct region. MAIN OUTCOME MEASURES： Heart functional parameters were compared between both groups 6 weeks following myocardial infarction. Differentiation of BM-MNCs was observed under a fluorescence microscope. Changes in muscular tissues at infarct regions in the transplantation group were observed with a transmission electron microscope. RESULTS： A total of 16 canines were included, no death. 2 hours following ligation, purple muscle tissues were found in distal end of ligation point; ventricle wall activity became weaken. Electrocardiogram showed higher ST segment. Compared with the control group, no significant difference was detected in each indice 6 weeks and 2 hours following myocardial infarction （P 〉 0.05）. Left ventdcular ejection fraction, left ventricular end-systolic dimension and left ventricular shortening fraction were significantly improved between 6 weeks and 2 hours in the transplantation group （P 〈 0.01 ）, and left ventricular ejection fraction was significantly improved compared with the control group （P 〈 0.05）. Left ventdcular ejection fraction was 7% higher in the transplantation group compared with the control group. Under a fluorescence microscope, BM-MNCs were distributed in and surrounding the infarct region, and expressed myosin heavy chain. No transplanted cells were found in normal myocardial tissue and control group. Vascular endothelial cells and cardiomyogenic cells could be found in the transplantation group by transmission electron microscopy. CONCLUSION： BM-MNCs can differentiate into cardiomyogenic cells in and surrounding the infarct region, and can promote angiogenesis and improve cardiac function.