You Fei, Shen Yibo, Hao Yuanyuan
Department of Cardiology, Xi'an Central Hospital No. 161 Xiwu Road, Xincheng District, Xi'an 710004, Shaanxi, China.
School of Medicine, Yan'an University No. 580 Shengdi Road, Baota District, Yan'an 716000, Shaanxi, China.
Am J Transl Res. 2024 Nov 15;16(11):6528-6539. doi: 10.62347/VXND1945. eCollection 2024.
To elucidate the regulatory effect of exosomes secreted by bone marrow mesenchymal stem cells (BMSCs-exosomes) on cardiomyocyte apoptosis through miRNA-let-7i-5p in myocardial infarction.
BMSCs-exosomes were extracted, and their morphology and size distribution were analyzed using transmission electron microscope. Expression of exosome surface markers was determined by western blot. H9C2 cells were randomly assigned into five groups, namely control, OGD, OGD+exos, OGD+exos+miR-let-7i-5p inhibitor and OGD+exos+miR-let-7i-5p inhibitor NC. Hypoxic cardiomyocytes were induced using glucose-free Dulbecco's Modified Eagle Medium (DMEM). Mice were randomly assigned into sham, myocardial infarction (MI), MI+exos, MI+exos+miR-let-7i-5p inhibitor and MI+exos+miR-let-7i-5p inhibitor NC groups. MI model was established by ligation of the left anterior descending (LAD) coronary artery. Subsequently, BMSCs-exosomes or BMSCs-exosomes transfected with miRNA-let-7i-5p inhibitor were incubated with hypoxia cardiomyocytes or injected into the MI mouse model. Cell survival was accessed by CCK-8 assay. Cardiomyocyte apoptosis was accessed with V-FITC/PI and TUNEL. Heart function of MI mice was evaluated by echocardiography. Myocardial infarct size was calculated through TTC staining. Relative miRNA-let-7i-5p expression level was determined by RT-qPCR. Expression of apoptosis-related proteins in myocardial tissue were detected by western blot.
Exosomes secreted from BMSCs were successfully extracted. In H9C2 cells, miRNA-let-7i-5p expression was significantly upregulated, cell survival rate was increased, and the apoptosis rate was decreased after incubation with BMSCs-exosomes. In MI mice, injection of BMSCs-exosomes markedly upregulated miRNA-let-7i-5p level, reduced infarct size, improved cardiac function, and decreased apoptotic rate. BMSCs-exosomes treatment downregulated Bax and upregulated Bcl-2 protein expression. These effects were reversed by transfection with the miRNA-let-7i-5p inhibitor.
BMSCs-exosomes inhibit myocardial apoptosis, attenuate MI progression, and protect against myocardial infarction both and through miRNA-let-7i-5p.
阐明骨髓间充质干细胞分泌的外泌体（BMSCs-外泌体）通过miRNA-let-7i-5p对心肌梗死中心肌细胞凋亡的调节作用。
提取BMSCs-外泌体，用透射电子显微镜分析其形态和大小分布。通过蛋白质印迹法检测外泌体表面标志物的表达。将H9C2细胞随机分为五组，即对照组、氧糖剥夺组（OGD）、OGD+外泌体组、OGD+外泌体+miR-let-7i-5p抑制剂组和OGD+外泌体+miR-let-7i-5p抑制剂阴性对照组。使用无糖杜氏改良 Eagle 培养基（DMEM）诱导缺氧心肌细胞。将小鼠随机分为假手术组、心肌梗死组（MI）、MI+外泌体组、MI+外泌体+miR-let-7i-5p抑制剂组和MI+外泌体+miR-let-7i-5p抑制剂阴性对照组。通过结扎左冠状动脉前降支（LAD）建立MI模型。随后，将BMSCs-外泌体或转染了miRNA-let-7i-5p抑制剂的BMSCs-外泌体与缺氧心肌细胞孵育或注射到MI小鼠模型中。通过CCK-8法检测细胞存活率。用V-FITC/PI和TUNEL法检测心肌细胞凋亡。通过超声心动图评估MI小鼠的心功能。通过TTC染色计算心肌梗死面积。通过RT-qPCR测定相对miRNA-let-7i-5p表达水平。通过蛋白质印迹法检测心肌组织中凋亡相关蛋白的表达。
成功提取了BMSCs分泌的外泌体。在H9C2细胞中，与BMSCs-外泌体孵育后，miRNA-let-7i-5p表达显著上调，细胞存活率增加，凋亡率降低。在MI小鼠中，注射BMSCs-外泌体显著上调miRNA-let-7i-5p水平，减小梗死面积，改善心功能，并降低凋亡率。BMSCs-外泌体处理下调Bax表达并上调Bcl-2蛋白表达。用miRNA-let-7i-5p抑制剂转染可逆转这些作用。
BMSCs-外泌体通过miRNA-let-7i-5p抑制心肌细胞凋亡，减轻MI进展，并预防心肌梗死。
