大鼠骨髓间充质干细胞经热休克处理后对损伤心肌的修复作用

目的 探讨大鼠骨髓间充质干细胞(MSC)经热休克处理后对低血清培养的耐受性变化及对心肌梗死大鼠心功能的改善作用.方法 将体外培养的MSC经热休克处理(42℃、30 min)后,用免疫印迹方法检测热休克蛋白70(HSP-70)的表达;处理后的MSC进行低血清培养,Annexln试剂盒检测培养不同时间后MSC的凋亡率及死亡率.制作大鼠心肌梗死模型,并移植经热休克处理后的MSC,用超声心动及血流动力学方法检测大鼠心功能的变化.结果 经热休克处理后的MSC表达CD90、CD44、CD105、CD54,不表达CD34、CD45、CD31等与造血细胞和内皮细胞相关的抗原,表达水平与未处理组无显著性差异.与未经处理的MSC比较,经热休克处理后的MSC HSP-70表达量明显增高;在低血清培养条件下,48、72和96 h的细胞凋亡率较未处理组相应时间明显降低;培养72和96 h后的细胞死亡率较未处理组明显降低.急性心肌梗死大鼠移植经热休克处理后的MSC,8周后左室射血分数(LVEF)、左室收缩压峰值(LVSP)、左室压力最大上升或下降速率(+dp/dtmax,-dp/dtmax)较移植对照组均明显升高,左室舒张末压(LVEDP)明显下降;短轴缩短率(FS)有升高趋势,但无统计学意义.结论 MSC经热休克处理后,免疫表型未发生变化,但热休克蛋白表达量增高,能提高对低血清培养条件的耐受性;心肌梗死大鼠移植经热休克处理后的MSC可以明显改善心功能.

Repair potential of heat-treated rat bone marrow mesenchymal stem cells in infarcted myocardium

Objective To study the effects of heat shock treatment of rat bone marrow mesenehymal stem cells(MSCs),the apoptosis ratio of treated-cells under low serum condition and the treated-cells transplantation on left ventricular function in rats with myocardiaIinfarction.Methods MSC8 were heat-treated under 42℃for 30 min,then the heat shock protein-70(HSP-70)was detected bv Western blot.The apoptosis ratio of heat-treated MSCs under low serum condition was tested by Annexin kit.The treated-MSCs labeled with Dil were transplanted into infarcted myocardium and 8 weeks later,the cardiac function of rats in each group was evaluated by echocardiography and cardiac catheterization.Results The immunophenotype of heat-treated MSCs did not vary,Western blot confirmed a higher level expression of HSP-70 in the treated-MSCs group as compared with that in the control group.The early apoptosis ratio was lower in treated-MSCs measured by flow cytometry with annexin staining than that of MSCs when cultured with low serum medium.After 8 weeks,LVEF,LVSP,+dp/dtmax,and-dp/dtmax were significantly higher,and the LVEDP was significantly lowar in heat-treated MSCs transplantation group than that in the control group.Conclusions Heat shock pretreatment of MSCs enhances the tolerance of MSCs to low serum medium,whereas does not lcad to the change of the cell immunophenotype.Transplantation of heattreated MSCs might improve the cardiac function in a rat myocardialinfarction model.