Mesenchymal stem cell (MSC)-derived exosomes emerge as promising candidates for treating delayed wound healing in diabetes due to the promotion of angiogenesis. Preconditioned MSC with chemical or biological factors could possibly enhance the biological activities of MSC-derived exosomes. The purpose of this research focused on whether exosomes derived from the bone marrow MSC (BMSC) pretreated with atorvastatin (ATV), could exhibit better pro-angiogenic ability in diabetic wound healing or not and its underlying molecular mechanism. We isolated exosomes from non-pretreated BMSC (Exos) and ATV pretreated BMSC (ATV-Exos) and evaluated their characterization by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and Western blotting. In vivo, we made full-thickness skin defects in streptozotocin (STZ)-induced diabetic rats and the defects received multiple-point injection with PBS, Exos, or ATV-Exos. Two weeks later, histological analysis was conducted to evaluate the impact of different treatments on wound healing and the neovascularization was measured by micro-CT. In vitro, cell proliferation, migration, tube formation, and vascular endothelial growth factor (VEGF) secretion were measured in human umbilical vein endothelial cells (HUVEC). The role of miRNAs and AKT/eNOS signaling pathway in the promoted angiogenesis of ATV-Exos were assessed with their inhibitors. No significant difference in morphology, structure, and concentration was observed between ATV-Exos and Exos. In STZ-induced diabetic rats, ATV-Exos exhibited excellent abilities in facilitating the wound regeneration by promoting the formation of blood vessels compared with Exos without influencing liver and kidney function. Meanwhile, ATV-Exos promoted the proliferation, migration, tube formation, and VEGF level of endothelial cells in vitro. And AKT/eNOS pathway was activated by ATV-Exos and the pro-angiogenic effects of ATV-Exo were attenuated after the pathway being blocked. MiR-221-3p was upregulated by ATV-Exos stimulation, and miR-221-3p inhibitor suppressed the pro-angiogenesis effect of ATV-Exos. Exosomes originated from ATV-pretreated MSCs might serve as a potential strategy for the treatment of diabetic skin defects through enhancing the biological function of endothelial cells via AKT/eNOS pathway by upregulating the miR-221-3p.

中文翻译：

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来自阿托伐他汀预处理的MSC的外泌体通过增强经由AKT / eNOS途径的血管生成来加速糖尿病伤口的修复。

间充质干细胞（MSC）衍生的外来体由于促进血管生成而成为治疗糖尿病中延迟伤口愈合的有希望的候选者。具有化学或生物学因素的预处理MSC可能会增强MSC衍生的外泌体的生物学活性。这项研究的目的集中在用阿托伐他汀（ATV）预处理的骨髓MSC（BMSC）衍生的外泌体能否在糖尿病伤口愈合中表现出更好的促血管生成能力及其潜在的分子机制。我们从未预处理的BMSC（Exos）和ATV预处理的BMSC（ATV-Exos）中分离了外泌体，并通过透射电子显微镜（TEM），纳米颗粒跟踪分析（NTA）和Western印迹评估了它们的表征。体内，我们在链脲佐菌素（STZ）诱导的糖尿病大鼠中制作了全层皮肤缺损，并用PBS，Exos或ATV-Exos进行了多点注射。两周后，进行组织学分析以评估不同治疗方法对伤口愈合的影响，并通过微型CT测量新生血管形成。在体外，在人脐静脉内皮细胞（HUVEC）中测量细胞增殖，迁移，管形成和血管内皮生长因子（VEGF）的分泌。用其抑制剂评估了miRNA和AKT / eNOS信号通路在ATV-Exos促进血管生成中的作用。在ATV-Exos和Exos之间没有观察到形态，结构和浓度的显着差异。在STZ诱导的糖尿病大鼠中，与Exos相比，ATV-Exos在促进血管形成方面具有出色的促进伤口再生的能力，并且不影响肝肾功能。同时，ATV-Exos促进了内皮细胞的增殖，迁移，管形成和VEGF水平。AKT / eNOS途径被ATV-Exos激活，阻断后，ATV-Exo的促血管生成作用减弱。ATV-Exos刺激上调了MiR-221-3p，miR-221-3p抑制剂抑制了ATV-Exos的促血管生成作用。源自ATV预处理的MSC的外泌体可能通过上调miR-221-3p通过AKT / eNOS途径增强内皮细胞的生物学功能，从而成为治疗糖尿病皮肤缺损的潜在策略。