MRI评价骨髓间质干细胞治疗猪急性心肌梗死效果的实验研究

MRI assessment of acute myocardial infarction with transplantation of autologous mesenchymai stem cells in swine：an experimental study

目的 应用MRI评价经冠状动脉途径移植猪自体骨髓间质干细胞（BM—MSCs）治疗急性心肌梗死（AMI）的治疗效果。方法8月龄中华小型猪14只[（27±3）kg]，平均分成移植组与对照组。胶圈套扎左前降支第一对角支分叉以远90min后松开，建成AMI模型。心肌梗死后1周进行细胞移植，将干细胞悬液（移植组：1×10^3／ml×10ml）或无血清培养液（DMEM）（对照组10ml）经微导管注入前降支。AMI术后1周（基线）和MSCs移植后6周（终点）各行1次MR扫描，评价移植前后心脏形态、功能、心肌灌注及延迟增强。第2次MR扫描后立即处死动物，分别行冰冻切片、石蜡切片和电镜观察。结果与对照组比较，移植组在移植6周后左心室整体功能较前明显改善，实验组与对照组比较，左心室平均射血分数（EF）值从（42．7±7．5）％升至（50．1±10．1）％（P〈0．01），左心室节段运动异常数平均减少4个（P〈0．01）、梗死面积减少3．2cm^2（P〈0．01），心脏重量指数增加4．1s／m^2（P〈0．05）。病理证实移植组梗死区和梗死周边的病变情况显著轻于对照组，有大量存活心肌，纤维化程度显著减轻；并且可见核大、边集，胞质丰富的幼稚细胞；在梗死区和梗死周边区组织的冰冻切片上可见4-6-二脒基二苯基吲哚（DAPI）阳性的移植细胞存活。免疫荧光检测进一步表明大部分DAPI阳性细胞表达心肌特异性肌钙蛋白T（troponinT），并且表达间隙连接蛋白43（connexin43）。部分DAPI阳性细胞表达平滑肌肌动蛋白（smooth muscleactin）和血管性血友病因子（Yon Wiilebrand），移植组梗死周边区毛细血管密度显著高于对照组[分别为（8．7±2．0）、（4．9±1．3）个／高倍镜]（P〈0．01）。结论 MRI可作为猪BM-MSCs在体移植前后评价其治疗效果的可靠影像检查方法。

Objective To investigate the effects of autologous bone marrow-derived mesenchymal stem cells （ MSCs ） transplantation on acute myocardial infarction in swine models using MRI. Methods Fourteen Chinese mini-pigs （27 ± 3 kg） were divided into control group （n = 7 ） and transplantation group （ n = 7）. Acute myocardial infarction （AMI） model was made by occlusion of the left anterior descending coronary artery for 90 minutes, and then 10 ml autologous MSCs （3 × 10^6 cell / ml） were injected into LAD by over-wire-balloon catheter after one week. MRI was performed to assess the cardiac function and myocardial perfusion 1 week after AMI and 6 weeks after transplantation. The implanted cells in vitro were analyzed by immunofluorescence. Results The left ventricular ejection fraction （LVEF） in transplantation group was increased from （42. 7 ±7.5） % to （50. 1 ±10. 1 ） % , which was significantly different from that in control group （P 〈0. 01 ）. In addition, the dyskinetic segments in infarcted region and the infarcted area were decreased by 4 and 3.2 cm^2 respectively （ P 〈 0.01 ）, and the left ventricular weight index was increased by 4. 1 g/m^2 in transplantation group（ P 〈0.05 ） compared with control group. The DAPI-labeled cells in infarcted and peri-infarcted region indicated the survived MSCs. Immunofluorescence also confirmed that those cells expressed cardiomyocyte-specific troponin T, connexin 43 and vessel-specific smooth muscle actin. Capillary density in both infarcted and peri-infarcted region were higher in transplantation group than the control group （P 〈 0. 01 ）. Conclusion MRI is a reliable imaging method for assessing the effects of stem cell transplantation in acute myocardial infartion of swine models.