Background: 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. Methods: 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). Results: 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. Conclusions: 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. Graphical MT-Exo promotes diabetic wound healing by regulating M1 and M2 macrophage polarization.:

Background: 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. Methods: 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. Results: 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. Conclusions: 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.

Accumulating evidences showed metformin and berberine, well‐known glucose‐lowering agents, were able to inhibit mitochondrial electron transport chain at complex I. In this study, we aimed to explore the antihyperglycaemic effect of complex I inhibition. Rotenone, amobarbital and gene silence of NDUFA13 were used to inhibit complex I. Intraperitoneal glucose tolerance test and insulin tolerance test were performed in db/db mice. Lactate release and glucose consumption were measured to investigate glucose metabolism in HepG2 hepatocytes and C2C12 myotubes. Glucose output was measured in primary hepatocytes. Compound C and adenoviruses expressing dominant negative AMP‐activated protein kinase (AMPK) α1/2 were exploited to inactivate AMPK pathway. Cellular NAD⁺/NADH ratio was assayed to evaluate energy transforming and redox state. Rotenone ameliorated hyperglycaemia and insulin resistance in db/db mice. It induced glucose consumption and glycolysis and reduced hepatic glucose output. Rotenone also activated AMPK. Furthermore, it remained effective with AMPK inactivation. The enhanced glycolysis and repressed gluconeogenesis correlated with a reduction in cellular NAD⁺/NADH ratio, which resulted from complex I suppression. Amobarbital, another representative complex I inhibitor, stimulated glucose consumption and decreased hepatic glucose output in vitro, too. Similar changes were observed while expression of NDUFA13, a subunit of complex I, was knocked down with gene silencing. These findings reveal mitochondrial complex I emerges as a key drug target for diabetes treatment. Inhibition of complex I improves glucose homoeostasis via non‐AMPK pathway, which may relate to the suppression of the cellular NAD⁺/NADH ratio.

Although metabolomics are desirable to understand the pathophysiology of gestational diabetes mellitus (GDM), comprehensive metabolomic studies of GDM are rare. We aimed to offer a holistic view of metabolites alteration in GDM patients and investigate the possible multimarker models for GDM diagnosis. Biochemical parameters and perinatal data of 131 GDM cases and 138 controls were collected. Fasting serum samples at 75 g oral glucose tolerance test were used for metabolites by ultra performance liquid chromatography-quadrupole-time of flight-mass spectrometry, ultra performance liquid chromatography-triple triple-quadrupole-mass spectrometry and gas chromatography- time-of- flight mass spectrometry platforms. Significant changes were observed in free fatty acids, bile acids, branched chain amino acids, organic acids, lipids and organooxygen compounds between two groups. In receiver operating characteristic (ROC) analysis, different combinations of candidate biomarkers and metabolites in multimarker models achieved satisfactory discriminative abilities for GDM, with the values of area under the curve (AUC) ranging from 0.721 to 0.751. Model consisting of body mass index (BMI), retinol binding protein 4 (RBP4), n-acetylaspartic acid and C16:1 (cis-7) manifested the best discrimination [AUC 0.751 (95% CI: 0.693-0.809), P<0.001], followed by model consisting of BMI, Cystatin C, acetylaspartic acid and 6,7-diketoLCA [AUC 0.749 (95% CI: 0.691-0.808), P<0.001]. Metabolites alteration reflected disorders of glucose metabolism, lipid metabolism, amino acid metabolism, bile acid metabolism as well as intestinal flora metabolism in GDM state. Multivariate models combining clinical markers and metabolites have the potential to differentiate GDM subjects from healthy controls.

Diabetic wounds remain a serious clinical challenge whereas current therapies have limited effects on reducing the high disability and morbidity. Impaired vascularization is closely associated with delayed healing of diabetic wounds and liraglutide (Lira), a GLP-1R receptor agonist, has been reported to promote the angiogenic ability of endothelial cells. However, its application is hindered owing to the unsustainable drug concentration. In this study, we prepared a poly (lactic-co-glycolic acid)/gelatin (PLGA/Gel) nanofibrous mat scaffold to sustain the release of Lira for skin tissue engineering through 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxy sulfosuccinimide (EDC/NHS), a green cross-linking-graft integration method. The incorporation of Lira into PLGA/Gel increased the pore size, hydrophilicity, elasticity and degradation properties of nanofibrous mats, which were advantageous to wound healing. In addition, the effects on diabetic wound healing, vascularization and its underlying mechanism were evaluated. The results revealed that PLGA/Gel/Lira remarkably improved the healing efficiency of diabetic dermal wounds characterized by shortened wound closure time, increased blood vessel density, and elevated collagen deposition and alignment. In vitro, Lira reversed the inhibitory effects on proliferation, migration, tube differentiation, and VEGF secretion of endothelial cells induced by high glucose (HG). As for the underlying mechanism, Lira specifically decreased the level of miR-29b-3p, targeting the AKT/GSK-3β/β-catenin pathway to regulate the biological function of endothelial cells. In conclusion, for the first time this study combined PLGA/Gel with Lira to take advantage of their synergistic effects to promote vascularization, a promising strategy to accelerate diabetic wound repair.