After surgery, wound recovery in diabetic patients may be disrupted due to delayed inflammation, which can lead to undesired consequences, and there is currently a lack of effective measures to address this issue. Mesenchymal stem cell (MSC)-derived exosomes (Exo) have been proven to be appropriate candidates for diabetic wound healing through the anti-inflammatory effects. In this study, we investigated whether melatonin (MT)-pretreated MSCs-derived exosomes (MT-Exo) could exert superior effects on diabetic wound healing, and we attempted to elucidate the underlying mechanism. For the evaluation of the anti-inflammatory effect of MT-Exo, in vitro and in vivo studies were performed. For in vitro research, we detected the secreted levels of inflammation-related factors, such as IL-1β, TNF-α and IL-10 via ELISA and the relative gene expression of the IL-1β, TNF-α, IL-10, Arg-1 and iNOS via qRT-PCR and investigated the expression of PTEN, AKT and p-AKT by Western blotting. For in vivo study, we established air pouch model and streptozotocin (STZ)-treated diabetic wound model, and evaluated the effect of MT-Exo by flow cytometry, optical imaging, H&E staining, Masson trichrome staining, immunohistochemical staining, immunofluorescence, and qRT-PCR (α-SMA, collagen I and III). MT-Exo significantly suppressed the pro-inflammatory factors IL-1β and TNF-α and reduced the relative gene expression of IL-1β, TNF-α and iNOS, while promoting the anti-inflammatory factor IL-10 along with increasing the relative expression of IL-10 and Arg-1, compared with that of the PBS, LPS and the Exo groups in vitro. This effect was mediated by the increased ratio of M2 polarization to M1 polarization through upregulating the expression of PTEN and inhibiting the phosphorylation of AKT. Similarly, MT-Exo significantly promoted the healing of diabetic wounds by inhibiting inflammation, thereby further facilitating angiogenesis and collagen synthesis in vivo. MT-Exo could promote diabetic wound healing by suppressing the inflammatory response, which was achieved by increasing the ratio of M2 polarization to M1 polarization through activating the PTEN/AKT signalling pathway, and the pretreatment of MT was proved to be a promising method for treating diabetic wound healing.

中文翻译：

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褪黑素刺激的MSC衍生的外泌体通过靶向PTEN / AKT途径来调节巨噬细胞M1和M2极化，从而改善糖尿病伤口的愈合。

手术后，由于延迟发炎，糖尿病患者的伤口恢复可能会中断，这可能导致不良后果，并且目前缺乏解决此问题的有效措施。骨髓间充质干细胞（MSC）衍生的外泌体（Exo）已被证明可通过抗炎作用成为糖尿病伤口愈合的合适候选者。在这项研究中，我们调查了褪黑素（MT）预处理的MSCs衍生的外泌体（MT-Exo）是否可以对糖尿病伤口愈合产生更好的作用，并且我们试图阐明其潜在机制。为了评估MT-Exo的抗炎作用，进行了体外和体内研究。在体外研究中，我们检测到了炎症相关因子（例如IL-1β，ELISA法检测TNF-α和IL-10的表达，qRT-PCR检测IL-1β，TNF-α，IL-10，Arg-1和iNOS的相对基因表达，并通过PTEN，AKT和p-AKT的表达进行研究。蛋白质印迹。对于体内研究，我们建立了气囊模型和链脲佐菌素（STZ）处理的糖尿病伤口模型，并通过流式细胞仪，光学成像，H＆E染色，Masson三色染色，免疫组织化学染色，免疫荧光和qRT评估了MT-Exo的效果-PCR（α-SMA，I型和III型胶原）。MT-Exo显着抑制促炎因子IL-1β和TNF-α并降低IL-1β，TNF-α和iNOS的相对基因表达，同时促进抗炎因子IL-10并同时增加相对表达与PBS，LPS和Exo组的体外IL-10和Arg-1相比。通过上调PTEN的表达并抑制AKT的磷酸化，M2极化与M1极化的比率增加，从而介导了这种作用。同样，MT-Exo通过抑制炎症反应显着促进了糖尿病伤口的愈合，从而进一步促进了体内血管生成和胶原蛋白的合成。MT-Exo可以通过抑制炎症反应来促进糖尿病伤口的愈合，这是通过激活PTEN / AKT信号通路增加M2极化与M1极化的比率来实现的，事实证明MT的预处理是一种有前途的治疗方法糖尿病伤口愈合。MT-Exo通过抑制炎症反应显着促进了糖尿病伤口的愈合，从而进一步促进了体内血管生成和胶原蛋白的合成。MT-Exo可以通过抑制炎症反应来促进糖尿病伤口的愈合，这是通过激活PTEN / AKT信号通路增加M2极化与M1极化的比率来实现的，事实证明MT的预处理是一种有前途的治疗方法糖尿病伤口愈合。MT-Exo通过抑制炎症反应显着促进了糖尿病伤口的愈合，从而进一步促进了体内血管生成和胶原蛋白的合成。MT-Exo可以通过抑制炎症反应来促进糖尿病伤口的愈合，这是通过激活PTEN / AKT信号通路增加M2极化与M1极化的比率来实现的，事实证明MT的预处理是一种有前途的治疗方法糖尿病伤口愈合。