Hemin Enhances The Cardioprotective Effects Of Mesenchymal Stem Cell-derived Exosomes Against Myocardial Infarction

ObjectiveMesenchymal stem cell-derived exosomes(MSC-EXO)has been demonstrated to be a novel therapeutic strategy for myocardial infarction(MI).Our previous study revealed that pretreatment with Hemin,a potent heme oxygenase-1(HO-1)inducer,enhanced the effects of MSCs for recovery of cardiac functions in a mouse model of MI.This study aimed to examine the cardioprotective effects of EXO derived from Hemin-pretreated MSCs(Hemin-MSC-EXO)on MI and explore the potential mechanisms.MethodsMSC-EXO and Hemin-MSC-EXO were isolated and purified.Myocardial infarction was induced by ligation of left anterior descending coronary artery.The heart function of mice was examined by echocardiography among different groups.The percentage of infarct size was determined by Masson’s Trichrome staining.The senescence of heart sections was evaluated by SA-β-gal staining、Troponin/p21 double staining and Western Blotting.The mitochondrial dynamics were examined by Transmission Electron Microscope(TEM).In vitro,we used MitoTracker Green staining to detect the mitochondrial morphology of neonatal mice cardiomyocytes(NMCMs)under serum deprivation and hypoxic(SD/H)condition.The cellular senescence of NMCMs was determined by SA-β-gal assay.miRNA-seq analysis revealed the differentially expressed miRNAs between MSC-EXO and Hemin-MSC-EXO.The level of miR-183-5p was measured by RT-PCR.ResultsMSC-EXO and Hemin-MSC-EXO were both successfully isolated.There were no significant differences in morphology,size and size distribution between MSCEXO and Hemin-MSC-EXO.Hemin enhanced the particle concentration and the level of exosomal molecular markers.Compared with MSC-EXO,injection of Hemin-MSC-EXO signifcantly improved cardiac function and reduced fibrosis.In vitro and in vivo,the cardiomyocyte senescence and mitochondrial fission were ameliorated in both MSC-EXO and Hemin-MSC-EXO group.Compared with MSC-EXO,Hemin-MSC-EXO exhibited better cardioprotective effects.The level of miR-183-5p was higher in Hemin-MSC-EXO than in MSC-EXO by the MicroRNA sequencing.Knockdown of miR-183-5p reduced the protective effects of Hemin-MSC-EXO and partially abrogated the attenuating mitochondrial fission and cellular senescence of cardiomyocytes induced by SD/H.The abundance of the high mobility group box-1(HMGB1)was lower in Hemin-MSC-EXO group.HMGB1 was one of the potential target genes of miR-183-5p.The mechanism of Hemin-MSC-EXO inhibited SD/H induced cardiomyocyte senescence was partially mediated by miR-183-5p via regulation of the HMGB1/ERK/Drp1 signaling pathway.miR-183-5p knockdown reduced the cardioprotective effects of Hemin-MSC-EXO in MI.ConclusionsOur results show that Hemin signifificantly enhanced the therapeutic efficacy of MSC-EXO for treatment of MI.Hemin-MSC-EXO could inhibit cardiomyocyte senescence through miR-183-5p.Exosomal miR-183-5p facilitates cardiac repair via regulation of the HMGB1/ERK/Drpl pathway.These results may provide a new insight into the applications of MSC-EXO in the therapy of MI.