Exosome/metformin-loaded self-healing conductive hydrogel rescues microvascular dysfunction and promotes chronic diabetic wound healing by inhibiting mitochondrial fission

Chronic diabetic wounds remain a globally recognized clinical challenge.They occur due to high concentrations of reactive oxygen species and vascular function disorders.A promising strategy for diabetic wound healing is the delivery of exosomes,comprising bioactive dressings.Metformin activates the vascular endothelial growth factor pathway,thereby improving angiogenesis in hyperglycemic states.However,multifunctional hydrogels loaded with drugs and bioactive substances synergistically promote wound repair has been rarely reported,and the mechanism of their combinatorial effect of exosome and metformin in wound healing remains unclear.Here,we engineered dual-loaded hydrogels possessing tissue adhesive,antioxidant,self-healing and electrical conductivity properties,wherein 4-armed SH-PEG cross-links with Ag^(+),which minimizes damage to the loaded goods and investigated their mechanism of promotion effect for wound repair.Multiwalled carbon nanotubes exhibiting good conductivity were also incorporated into the hydrogels to generate hydrogen bonds with the thiol group,creating a stable three-dimensional structure for exosome and metformin loading.The diabetic wound model of the present study suggests that the PEG/Ag/CNT-M+E hydrogel promotes wound healing by triggering cell proliferation and angiogenesis and relieving peritraumatic inflammation and vascular injury.The mechanism of the dual-loaded hydrogel involves reducing the level of reactive oxygen species by interfering with mitochondrial fission,thereby protecting F-actin homeostasis and alleviating microvascular dysfunction.Hence,we propose a drug-bioactive substance combination therapy and provide a potential mechanism for developing vascular function-associated strategies for treating chronic diabetic wounds.

The Notch pathway attenuates burn-induced acute lung injury in rats by repressing reactive oxygen species

Background:Acute lung injury(ALI)is a common complication following severe burns.The underlying mechanisms of ALI are incompletely understood;thus,available treatments are not sufficient to repair the lung tissue after ALI.Methods:To investigate the relationship between the Notch pathway and burn-induced lung injury,we established a rat burn injury model by scalding and verified lung injury via lung injury evaluations,including hematoxylin and eosin(H&E)staining,lung injury scoring,bronchoalveolar lavage fluid and wet/dry ratio analyses,myeloperoxidase immunohistochemical staining and reac-tive oxygen species(ROS)accumulation analysis.To explore whether burn injury affects Notch1 expression,we detected the expression of Notch1 and Hes1 after burn injury.Then,we extracted pulmonary microvascular endothelial cells(PMVECs)and conducted Notch pathway inhibition and activation experiments,via aγ-secretase inhibitor(GSI)and OP9-DLL1 coculture,respectively,to verify the regulatory effect of the Notch pathway on ROS accumulation and apoptosis in burn-serum-stimulated PMVECs.To investigate the regulatory effect of the Notch pathway on ROS accumulation,we detected the expression of oxidative-stress-related molecules such as superoxide dismutase,nicotinamide adenine dinucleotide phosphate(NADPH)oxidase(NOX)2,NOX4 and cleaved caspase-3.NOX4-specific small interfering RNA(siRNA)and the inhibitor GKT137831 were used to verify the regulatory effect of the Notch pathway on ROS via NOX4.Results:We successfully established a burn model and revealed that lung injury,excessive ROS accumulation and an inflammatory response occurred.Notch1 detection showed that the expression of Notch1 was significantly increased after burn injury.In PMVECs challenged with burn serum,ROS and cell death were elevated.Moreover,when the Notch pathway was suppressed by GSI,ROS and cell apoptosis levels were significantly increased.Conversely,these parameters were reduced when the Notch pathway was activated by OP9-DLL1.Mechanistically,the inhibition of NOX4 by siRNA and GKT137831 showed that the Notch pathway reduced ROS production and cell apoptosis by downregulating the expression of NOX4 in PMVECs.Conclusions:The Notch pathway reduced ROS production and apoptosis by downregulating the expression of NOX4 in burn-stimulated PMVECs.The Notch-NOX4 pathway may be a novel therapeutic target to treat burn-induced ALI.

Overexpression of miR-101 suppresses collagen synthesis by targeting EZH2 in hypertrophic scar fibroblasts

Background:MicroRNA-101(miR-101)is a tumor suppressor microRNA(miRNA)and its loss is associated with the occurrence and progression of various diseases.However,the biological function and target of miR-101 in the pathogenesis of hypertrophic scars(HS)remains unknown.Methods:We harvested HS and paired normal skin(NS)tissue samples from patients and cultured their fibroblasts(HSF and NSF,respectively).We used quantitative reverse transcriptase polymerase chain reaction(qRT-PCR),fluorescence in situ hybridization(FISH),enzyme-linked immunosorbent assays(ELISA)and Western blot analyses to measure mRNA levels and protein expression of miR-101,enhancer of zeste homolog 2(EZH2),collagen 1 and 3(Col1 and Col3)andα-smooth muscle actin(α-SMA)in different in vitro conditions.We also used RNA sequencing to evaluate the relevant signaling pathways and bioinformatics analysis and dual-luciferase reporter assays to predict miR-101 targets.We utilized a bleomycin-induced fibrosis mouse model in which we injected miR-101 mimics to evaluate collagen deposition in vivo.Results:We found low expression of miR-101 in HS and HSF compared to NS and NSF.Overexpressing miR-101 decreased Col1,Col3 andα-SMA expression in HSF.We detected high expression of EZH2 in HS and HSF.Knockdown of EZH2 decreased Col1,Col3 andα-SMA in HSF.Mechanistically,miR-101 targeted the 3-untranslated region(3UTR)of EZH2,as indicated by the decreased expression of EZH2.Overexpressing EZH2 rescued miR-101-induced collagen repression.MiR-101 mimics effectively suppressed collagen deposition in the bleomycin-induced fibrosis mouse model.Conclusions:Our data reveal that miR-101 targets EZH2 in HS collagen production,providing new insight into the pathological mechanisms underlying HS formation.