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目的:探讨过表达GATA-4小鼠骨髓间充质干细胞(BMSCs)通过分泌外排体(exosome)修复心肌损伤的机制.方法:构建过表达GATA-4的小鼠BMSCs并提取其分泌的exosome.而后将GATA-4-BMSCs-ex-osome与BMSCs共同培养,空载体-BMSCs-exosome与BMSCs共同培养,BMSCs-exosome与BMSCs共同培养、BMSCs单独培养及小鼠心肌细胞单独培养48 h,采用Q-PCR定量检测心肌肌钙蛋白T(cTnT)、α肌动蛋白(α-actin)、连接蛋白43 (connexin 43)、结蛋白(Desmin)心肌特异性抗原表达量.再将过表达GATA-4BMSCs分泌的exosome与心肌细胞共培养,空载体-BMSCs分泌的exosome与心肌细胞共培养,BMSCs分泌的exosome与心肌细胞共培养及心肌细胞单独用于低氧培养无血清培养诱导细胞凋亡作为阳性对照培养48 h诱导细胞凋亡.采用流式细胞技术检测各组细胞的凋亡率.进一步采用TMT标记定量蛋白质组学分析过表达GATA-4小鼠BMSCs分泌exosome内有关细胞分化及抗凋亡的蛋白.结果:Q-PCR显示:过表达GATA-4-BMSCs分泌的exosome可以有效促进BMSCs向心肌细胞转化并具有极强的抗凋亡能力.蛋白质谱提示有8个蛋白有关细胞分化.有6个蛋白有关细胞调亡.其中Slit homolog 2 protein及Connective tissue growth factor蛋白既涉及细胞凋亡又涉及细胞分化.结论:过表达GATA-4-BMSCs分泌的exosome可以促进BMSCs向心肌细胞分化并具有抗凋亡能力.Slit homolog 2 protein及Connective tissue growth factor蛋白既涉及细胞凋亡又涉及细胞分化.“,”Objective:The present study aims to explore the mechanism of GATA-4-overexpressed mouse bone marrow mesenchymal stem cells (BMSCs) for cardiac repair via the exosomes.Method:Mouse bone marrow mesenchymal stem cells (BMSCs) were cultured and then transfected with GATA-4 gene by lentivirus-mediated way.Exosomes were extracted from cultured GATA-4-BMSC cell supernatants.The BMSCs were treated with GATA-4-BMSC-exosomes,free-vector-BMSC-exosomes,or BMSC-exosomes for 48 h,and then cocultured with mouse myocardial cells for another 48h.The expression levels of cTnT,α-actin,connexin 43,and the myocardial-specific antigen desmin were assessed by quantitative polymerase chain reaction (qPCR).Mouse myocardial cells were also treated with GATA-4-BMSC-exosomes,free-vector-BMSC-exosomes,or BMSC-exosomes for 48 h and then subjected to a hypoxic medium or a serum-free medium.The cell apoptosis rates were determined by flow cytometry.The proteins associated with cellular differentiation or anti-apoptosis were later analyzed by tandem mass tag (TMT) proteomics.Result:The qPCR results showed that the exosomes secreted from the BMSCs overexpressed with GATA-4 effectively facilitated the differentiation of BMSCs to form myocardial cells.The flow cytometry results suggested that the exosomes secreted from the BMSCs overexpressed with GATA-4 significantly inhibited apoptosis.The protein mass spectrometry data showed that there were eight key proteins associated with cellular differentiation and six proteins associated with apoptosis.Among them,the slit homolog 2 protein and connective tissue growth factor were associated with both apoptosis and cellular differentiation.Conclusion..Exosomes secreted from the BMSCs overexpressed with GATA-4 effectively facilitated the differentiation of BMSCs into myocardial cells and inhibited cell apoptosis.The proteins,slit homolog 2 protein and connective tissue growth factor,were associated with both apoptosis and cellular differentiation.