低氧增强骨髓间充质干细胞对缺氧诱导心肌细胞凋亡的可能性

背景：骨髓间充质干细胞移植入缺血心肌后存活率低,而低氧有可能增强骨髓间充质干细胞的增殖,促进其存活。目的：体外模拟心肌细胞缺血微环境,探索低氧预处理后,骨髓间充质干细胞对持续缺氧诱导的心肌细胞凋亡的保护作用。方法：取第4代SD大鼠骨髓间充质干细胞用于制备条件培养液。取胚胎大鼠心肌细胞株,随机分成4组：对照组：心肌细胞正常培养组;模型组：心肌细胞单纯缺氧;骨髓间充质干细胞组：心肌细胞与骨髓间充质干细胞条件培养液共缺氧;低氧组：心肌细胞与骨髓间充质干细胞低氧条件培养液共缺氧。MTT检测各组细胞活力变化,AnnexinV-FITC双染标记心肌细胞凋亡,免疫组化检测各组Bax和Bcl-2蛋白的表达。结果与结论：免疫组化显示,低氧组的Bcl-2表达较其他各组增强,而Bax的表达比模型组和骨髓间充质干细胞组减弱,Bcl-2/Bax比值最大。与对照组和骨髓间充质干细胞组相比,低氧组的细胞活力高（P〈0.05）,凋亡率降低（P〈0.05）。提示低氧可能是通过增强旁分泌机制,从而对Bax和Bcl-2进行调节,对心肌细胞凋亡有保护效应。

Probability of bone marrow mesenchymal stem cells enhanced by hypoxia precondition against cardiomyocyte apoptosis induced by hypoxia

BACKGROUND：Bone marrow mesenchymal stem cells（BMSCs） have a lower survival rate after implanted into the ischemic myocardium.However,hypoxia precondition may enhance BMSCs proliferation and promote its survival rate.OBJECTIVE：To stimulate the micro-environment of myocardial ischemia in vitro,and to investigate the protective effect of BMSCs on cardiomyocytes apoptosis continually induced by hypoxia after the hypoxia precondition（HP）.METHODS：The 4th passage SD rats BMSCs were used to prepare conditioned medium.Embryonic cardiomyocytes from rats were randomly divided into 4 groups：cardiomyocytes culture under normal condition alone（normal group）,cardiomyocytes culture under hypoxia condition alone（model group）,cardiomyocytes co-cultured with conditioned medium of BMSCs under normal condition（BMSCs group）,cardiomyocytes co-cultured conditioned medium of BMSCs under hypoxia precondition（HP group）.Changes in cell viability were measured by MTT assay,cardiomyocytes apoptosis was labeled by Annexin V-FITC/PI staining,and the protein expression of Bax and Bcl-2 were detected by immunohistochemisty staining in each group.RESULTS AND CONCLUSION：The immunohistochemisty demonstrated that Bcl-2 expression in HP group was increased（P 0.05）,compared with control group,model group,and BMSCs group;While,compared with model group and BMSCs group,Bax expression in HP group was reduced,and the ratio of Bcl-2/Bax is maximum.Compared with control group and BMSCs group,cell viability in HP group was increased（P 0.05）,the apoptosis rate was reduced（P 0.05）.It suggested that HP may regulate Bax and Bcl-2 through the enhancement of paracrine mechanism,and which has a protective effect on cardiomyocytes apoptosis.