The Effect Of HIF-1α Over-expressed Mesenchymal Stem Cells-derived Exosomes In Myocardial Infarction

Aim:Ischemic heart Diseases(IHD)greatly threat people’s health due to their high mortality and morbidity.Traditional therapies,such as drugs,interventional surgery and open surgery could not reverse the ventricular remodeling after myocardial infarction.With the gradual loss of myocardial cells,end-stage cardiac failure will eventually happen,causing catastrophic consequences.The stem cell therapy is a promising method for myocardial infarction treatment.Researchers transplant stem cells into injury area to repair the damaged tissues via differentiation,angiogenesis or vascularization.A lot of achievements have been accomplished by restoring the normal biological function of injured tissue.However,recent researches reported low retention and survival rate of transplanted cells.In addition,the ischemic microenvironment is not favored for stem cells to differentiate into functional cells.Also,studies have indicated that the repair process is mostly attributed to the paracrine effect of stem cells rather than the direct differentiation ability.During this process,exosome plays a pivotal role.Exosome is a kind of extracellular vesicles that cells secret,with the diameter of 30-150 nm.Exosomes contribute a lot to the tissue damage repair and could carry various functional molecules,like proteins,mRNAs,microRNAs.In recent years,the protective effect of hypoxia inducible factor-1α(Hif-1α)in ischemic heart diseases treatment has been widely reported.Hif-1α could activate iNOS pathway and exert the protective effect.Based on these previous reports,this study aims to investigate the role of Hif-1α over-expressing exosomes in myocardial infarction treatment.Methods:In this study,we transduced Hif-1α mRNA into bone marrow-derived mesenchymal stem cells(MSCs)using lenti-virus.After the verification of eleveted Hif-1αexpression levelin exosomes,we isolated exosome from these MSCs,and further determined size distribution,morphology and membrane markers ofexosomes using Nanosight Tracking Analysis(NTA),transmission electron microscope(TEM)and western blot,respectively.For in vitro assays,we co-cultured exosome with hypoxia-injured human umbilical vascular endothelial cells(HUVEC)and determined the protective effect of exosomes via transwell assay and tube formation assay.For in vivo study,we injected exosomes through tail vein to myocardial infarcted rats.We performed ultrasound detection,H&E staining,masson’s trichrome staining,immunochemistry staining to determine the curative effect of exosomes.Results:The results showed that lenti-virus infection has elevated the expression of Hif-1α expression level in MSCs and MSC-derived exosomes.In vitro assays reported thatHif-1α over-expressed exosomes could reverse the injured migratory ability and tube formation ability of ischemic-injured HUVEC.In vivo assays indicated that Hif-la overexpressed exosomes could elevate the cardiac function of MI rats.Conclusion:Hif-la over-expressed exosomes could protect HUVEC from ischemic injury.Hif-la over-expressed exosomes could also restore the cardiac function,reduce fibrosis and increase neovascularization of ischemic area.