骨髓间充质干细胞和心脏Sca1阳性细胞移植治疗心肌梗死的效果比较及其机制研究

目的探讨骨髓来源的间充质干细胞(MSCs)和心脏来源的Sca1阳性干细胞移植对小鼠急性心肌梗死后的心功能恢复的影响。方法分别从成年C57BL/C小鼠的骨髓分离获取骨髓间充质干细胞,从心脏利用流式分选获取Sca1阳性干细胞,并在体外进行培养、扩增。C57BL/C小鼠雄性小鼠24只,按照以下方式分组,每组6只,假手术组,生理盐水对照组,MSCs治疗组和Sca1阳性细胞治疗组。小鼠麻醉后开胸,利用结扎心脏冠状动脉的左前降支建立急性心肌梗死模型,建模成功后分别在梗死区周围心肌内注射上述细胞或者生理盐水,假手术组小鼠不结扎冠状动脉。4周后,利用心脏超声观察小鼠左心室射血分数(LVEF)以及左心室舒张末期容积,以此评估心功能改变。细胞培养至第4代,采用荧光半定量PCR的方式分析细胞表达血管内皮生长因子(VEGFa和VEGFb)的情况。结果分离培养的骨髓MSCs贴壁生长,呈梭形;Sca1阳性干细胞在心脏组织的阳性率约为18%,培养后细胞贴壁生长,成短梭形,形态较MSCs更饱满。在细胞移植治疗后,与Sca1阳性干细胞治疗相比,MSCs治疗可以增加心梗后小鼠的存活率。细胞移植治疗4周后,骨髓来源MSCs治疗组的LVEF明显高于心脏来源Sca1阳性干细胞,且更有利于减少心梗后左心室舒张末期容积的扩大,改善心肌重塑。骨髓来源的MSCs表达VEGFa和VEGFb明显高于Sca1阳性细胞。结论心脏来源的Sca1阳性干细胞和骨髓来源的MSCs均可提高LVEF,促进心功能的恢复,且后者优于前者,这可能与MSCs高表达VEGF有关。

Comparison of the effect and mechanism of transplantation of bone marrow mesenchymal stem cells and cardiac sca1-positive stem cells on myocardial infarction

Objective　To investigate the therapeutic effect of bone marrow mesenchymal stem cell (MSCs) and cardiac-derived Sca1 positive stem cell on acute myocardial infarction model in mice.　Methods　Bone marrow mesenchymal stem cells were isolated from the femur bone marrow of adult C57BL/C mice, and Sca1 positive stem cells were harvested from the heart by flow cytometry. Twenty-four male C57BL/C mice were divided into four groups: sham group, control group, bone marrow MSCs treated group and Sca1 positive cells treated group. After anesthesia, the mouse thorax was opened and the left anterior descending coronary artery (LAD) was ligated to establish the acute myocardial infarction model. After successful LAD ligation, cells were injected into the infarcted myocardium. Four weeks later, cardiac ultrasound was used to observe heart function: the left ventricular ejection fraction (LVEF) and left ventricular (LV) end dilated volume. In addition, quantitative PCR was used to evaluate the RNA expression of VEGFa and VEGFb in cultured cells.　Results　The cultured bone marrow MSCs adhered to the dish and showed a spindle shape. The positive rate of Sca1 positive stem cells was about 18 %, and they also adhered to the dish while showed a short shuttle-like shape. Compared with Sca1positive stem cell therapy, MSCs treatment increased the survival rate of mice after myocardial infarction. After 4 weeks of cell transplantation therapy, the LVEF of the bone marrow-derived MSCs treatment group was significantly higher than that of the cardiac-derived Sca1 positive stem cell treatment group, while the LV end dilated volume was lower. The expression of VEGFa and VEGFb was significantly higher in bone-derived MSCs. 　Conclusion　Both bone marrow-derived MSCs and Cardiac-derived Sca1positive stem cells are beneficial to the improvement of cardiac function after infarction, and bone marrow-derived MSCs are superior in improving LVEF and inhibiting enlargement of left ventricular after myocardial infarction in mice, which may be caused by the high expression of VEGF in bone marrow derived MSC.