Delayed endothelial healing after drug eluting stent (DES) implantation is a critical clinical problem in treatment of coronary artery diseases. Exosomes exhibit proangiogenic potential in a variety of ischemic diseases. However, the association of exosomes with endothelial regeneration after DES implantation has been rarely reported. In this study, we aimed to investigate the therapeutic effects of mesenchymal stem cell (MSC)-derived exosomes on endothelial cells treated with rapamycin and explore the potential mechanisms of MSC-derived exosomes in promoting endothelial regeneration. Exosomes were isolated from MSCs by ultracentrifugation and identified by transmission electron microscopy, nanoparticle tracking analysis, and Western blot assay. The in vitro effects of MSC-derived exosomes on the proliferation and migration of endothelial cells treated with rapamycin were evaluated by integrated experiment, cell counting kit-8, scratch, tube formation, and transwell assays. And the apoptosis of rapamycin-induced endothelial cells loaded with MSC-derived exosomes was detected using TUNEL and Annexin-V FITC and PI double-staining assays. The microRNA (miRNA) cargo of MSC-derived exosomes was identified by high-throughput RNA sequencing. Pro-angiogenic miRNAs and key pathways were further characterized. Our results indicated that MSC-derived exosomes could be ingested into umbilical vein endothelial cells (HUVECs) and significantly enhanced cell proliferation rate, migratory and tube-forming capabilities in vitro. MSC-derived exosomes also inhibited the apoptosis of HUVECs induced by rapamycin. A distinct class of exosomal miRNAs was further identified, including six miRNAs tightly related to neovasculogenesis. Silencing the expression of exosomal miRNA-21–5p and let-7c-5p attenuated the pro-proliferative and pro-migratory capacity of MSC-derived exosomes. Moreover, functional enrichment analysis indicated that metabolic pathways might contribute to reendothelialization. This study highlights a proregenerative effect of MSC-derived exosomes in vitro, which may be partly explained by the delivery of pro-angiogenic miRNAs to endothelial cells.

药物洗脱支架（DES）植入后内皮的延迟愈合是治疗冠状动脉疾病的关键临床问题。外泌体在多种缺血性疾病中均表现出促血管生成的潜力。然而，很少有人报道外泌体与DES植入后的内皮再生有关。在这项研究中，我们旨在研究间充质干细胞（MSC）衍生的外泌体对雷帕霉素处理的内皮细胞的治疗作用，并探索MSC衍生的外泌体在促进内皮再生中的潜在机制。通过超速离心从MSC中分离外来体，并通过透射电子显微镜，纳米颗粒跟踪分析和Western印迹分析进行鉴定。在体外通过综合实验，细胞计数试剂盒8，刮擦，管形成和Transwell分析评估了MSC衍生的外来体对雷帕霉素处理的内皮细胞增殖和迁移的影响。并使用TUNEL和Annexin-V FITC和PI双重染色法检测载有MSC来源的外来体的雷帕霉素诱导的内皮细胞的凋亡。MSC来源的外泌体的microRNA（miRNA）货物是通过高通量RNA测序鉴定的。促血管生成的miRNA和关键途径得到了进一步表征。我们的研究结果表明，MSC衍生的外来体可以被摄取到脐静脉内皮细胞（HUVECs）和显著增强细胞增殖率，迁移和管形成的能力在体外。MSC衍生的外来体也抑制雷帕霉素诱导的HUVEC的凋亡。进一步鉴定出一类独特的外泌体miRNA，包括与新生血管生成紧密相关的六个miRNA。沉默外泌体miRNA-21-5p和let-7c-5p的表达可减弱MSC来源的外泌体的增殖和迁移能力。此外，功能富集分析表明代谢途径可能有助于内皮重塑。这项研究强调了MSC来源的外泌体在体外的促增殖作用，这可以部分由促血管生成的miRNA传递至内皮细胞来部分解释。