Keshtkar Somayeh, Kaviani Maryam, Sarvestani Fatemeh Sabet, Ghahremani Mohammad Hossein, Aghdaei Mahdokht Hossein, Al-Abdullah Ismail H, Azarpira Negar
Department of Molecular Medicine, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran.
Transplant Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
EXCLI J. 2020 Aug 3;19:1064-1080. doi: 10.17179/excli2020-2451. eCollection 2020.
Islet cell death and loss of function after isolation and before transplantation is considered a key barrier to successful islet transplantation outcomes. Mesenchymal stem cells (MSCs) have been used to protect isolated islets owing to their paracrine potential partially through the secretion of vascular endothelial growth factor (VEGF). The paracrine functions of MSCs are also mediated, at least in part, by the release of extracellular vesicles including exosomes. In the present study, we examined (i) the effect of exosomes from human MSCs on the survival and function of isolated mouse islets and (ii) whether exosomes contain VEGF and the potential impact of exosomal VEGF on the survival of mouse islets. Isolated mouse islets were cultured for three days with MSC-derived exosomes (MSC-Exo), MSCs, or MSC-conditioned media without exosomes (MSC-CM-without-Exo). We investigated the effects of the exosomes, MSCs, and conditioned media on islet viability, apoptosis and function. Besides the expression of apoptotic and pro-survival genes, the production of human and mouse VEGF proteins was evaluated. The MSCs and MSC-Exo, but not the MSC-CM-without-Exo, significantly decreased the percentage of apoptotic cells and increased islet viability following the downregulation of pro-apoptotic genes and the upregulation of pro-survival factors, as well as the promotion of insulin secretion. Human VEGF was observed in the isolated exosomes, and the gene expression and protein production of mouse VEGF significantly increased in islets cultured with MSC-Exo. MSC-derived exosomes are as efficient as parent MSCs for mitigating cell death and improving islet survival and function. This cytoprotective effect was probably mediated by VEGF transfer, suggesting a pivotal strategy for ameliorating islet transplantation outcomes.
胰岛在分离后和移植前的细胞死亡及功能丧失被认为是胰岛移植成功的关键障碍。间充质干细胞（MSCs）已被用于保护分离的胰岛，这部分归因于其通过分泌血管内皮生长因子（VEGF）发挥的旁分泌潜能。MSCs的旁分泌功能至少部分是由包括外泌体在内的细胞外囊泡的释放介导的。在本研究中，我们检测了（i）人MSCs来源的外泌体对分离的小鼠胰岛存活和功能的影响，以及（ii）外泌体是否含有VEGF以及外泌体VEGF对小鼠胰岛存活的潜在影响。将分离的小鼠胰岛与MSCs来源的外泌体（MSC-Exo）、MSCs或不含外泌体的MSCs条件培养基（MSC-CM-without-Exo）一起培养三天。我们研究了外泌体、MSCs和条件培养基对胰岛活力、凋亡和功能的影响。除了凋亡和促存活基因的表达外，还评估了人和小鼠VEGF蛋白的产生。MSCs和MSC-Exo，但不是MSC-CM-without-Exo，在下调促凋亡基因和上调促存活因子以及促进胰岛素分泌后，显著降低了凋亡细胞的百分比并提高了胰岛活力。在分离的外泌体中观察到了人VEGF，并且在用MSC-Exo培养的胰岛中，小鼠VEGF的基因表达和蛋白产生显著增加。MSCs来源的外泌体在减轻细胞死亡、改善胰岛存活和功能方面与亲代MSCs一样有效。这种细胞保护作用可能是由VEGF转移介导的，这提示了一种改善胰岛移植结果的关键策略。
