不同时间点移植自体骨髓间充质干细胞对心肌梗死后心功能改善的MRI研究

MRI study of transplanting autologous bone marrow mesenchymal stem cells at different time points on cardiac function amelioration following myocardial infarction

目的:观察心肌梗死后在不同时间点经冠状动脉自体移植骨髓间充质干细胞后对心功能的影响,并初步探讨其机制。方法:30只健康太湖梅山猪(分为6组)建立心肌梗死模型,并分离培养自体骨髓间充质干细胞。3组(每组5只)分别在心肌梗死后3h、2周及4周(分别简称为G1、G2、G4)经冠状动脉移植骨髓间充质干细胞。每组设立对照组(5只)在各对应时间点经冠状动脉注射DMEM培养基。在心肌梗死前,移植前及实验终点(心肌梗死8周)时对每只猪行MRI及心超检查以观察心功能的改变。在细胞移植前后不同时间点检测血清血管内皮生长因子值。实验终点时获取猪心,通过免疫组织化学检测移植细胞在心肌内定植及分化情况,并检测心肌血管密度。结果:G1组心功能与各对照组相比无显著性差异。G2、G4组与相应对照组相比,心功能指标有改善,且G4优于G2(P<0.05)。G1及各对照组心肌梗死面积减小百分比绝对值差异无显著性意义,G4组较G2组心肌梗死面积减小百分比绝对值大,差异有显著性意义(P<0.05)。G2、G4组血清血管内皮生长因子水平上升明显,而G1及各对照组血清血管内皮生长因子水平无明显变化,G4组上升幅度较G2组高(P<0.05)。G1及各对照组心肌切片免疫组织化学未见移植细胞定植及分化,G2、G4组心肌切片免疫组织化学显示有移植细胞定植及分化,且G4较G2优(P<0.05)。G1及各对照组心肌血管密度差异无显著性意义,心肌血管密度各实验组比较有显著性差异,G4组高于G1及G2组(P<0.05)。结论:心肌梗死后不同时间点移植骨髓间充质干细胞对心功能影响效果有差异;急性期移植对心功能无明显影响,非急性期移植能改善心功能。心肌梗死后4周移植治疗效果较优。MRI可以显示梗死心肌的部位及范围,并可以反映心功能的变化。

OBJECTIVE：To study the effect of transplanting autologous bone marrow mesenchymal stem cells （BMSCs） at different time point after myocardial infarction on cardiac function,and to approach its mechanism.METHODS：Thirty healthy Taihu Meishan swine were prepared for myocardial infarction models,and divided into 6 experimental groups,with 5 animals in each group.BMSCs were transplanted into 3 groups through coronary artery at 3 hours,2 weeks and 4 weeks after myocardial infarction,named G1,G2 and G4,respectively.Meantime,DMEM culture medium was injected in the control group at correspond periods.Each swine was examined by MRI and Doppler before infarction,before transplantation,and at 8 weeks after infarction,respectively,to observe the change of cardiac function.The VEGF values of blood serum in different periods after transplantation were detected.All swine hearts were harvested after 8 weeks （the experimental terminus）,and the planting and differentiation of transplanted cells in cardiac muscle were detected by the method of immunity histochemistry.The density of blood vessels in cardiac muscle was acquired simultaneously.RESULTS：There was no statistic difference of cardiac function between G1 and its control groups.The groups of G2 and G4 could improve cardiac function compared to the control groups,and G4 was superior to G2 （P 〈0.05）.There was no statistics difference of the decreased absolute value of myocardial infarcted area between G1 and the control groups.The myocardial infarcted area of G4 was greater than G2 （P〈0.05）.The value of blood serum VEGF rose obviously in the G2 and G4,while G1 and all control groups did not present any marked changes,the rising amplitude of G4 was larger than G2 （P〈0.05）.There were not any planting and differentiation of transplanted stem cells in G1 and all control groups at 8 weeks after infarction,but G2 and G4 could display,especially in G4 group （P〈0.05）.There was no statistic difference of the density of blood vessels in cardiac muscle between G1 and all control groups at 8 weeks after infarction,but the differences were significant in all experimental groups,which was superior in G4 group to G1 and G2 groups （P〈0.05）.CONCLUSION：There is disparity of transplanting BMSCs at different time point after myocardial infarction on cardiac function.Transplantation in acute period of myocardial infarction has no significant effect,but transplantation in non-acute period can ameliorate cardiac function.The therapeutic effect of transplanted at 4 weeks is superior to other time point.The MRI can display the location and compass of infarct cardiac muscle,and reflect the variation of cardiac function.