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,Annexin V-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.