Effects Of MicroRNA-206 Downregulation On The Sublethal Oxidative Stress Induced Premature Senescence In Mesenchymal Stem Cells

Aim:Coronary heart disease is prevalent in the elderly and easily causes myocardial infarction,acting as an important killer of human health.The current methods for treating coronary heart disease include drug therapy,surgical treatment,stem cell therapy,etc.Among these,stem cells(especially bone marrow-derived mesenchymal stem cells,BMSCs)therapy have received more attention,and are widely used in the treatment of heart diseases due to their easy availability,low immunogenicity and strong regenerative capacity.However,BMSCs obtained from elderly patients have limited therapy efficacy.Compared with young BMSCs,senescent BMSCs are less effective in treating myocardial infarction,which may be related to their decreased ability in proliferation,differentiation and cytokines secretion.At present,enormous studies have focused on how to optimize stem cells,thereby improving their regenerative capability and enhancing their therapy potential.Presently,miR-206 was confirmed to play an important role in the physiological process of cells,including cell proliferation,migration,apoptosis and survival.However,whether miR-206 is involved in the senescent process of BMSCs and by which molecular mechanisms remains unknown.In this study,we aimed to elucidate effects of miR-206 on the senescent process of BMSCs as well as the underlying mechanisms.Methods:In this study,we firstly treated BMSCs with hydrogen peroxide(H2O2)to conduct senescent model,and then performed EdU and transwell assay to detect the proliferation ability and migration ability of senescent BMSCs.Meanwhile,we predicted the target gene of microRNA-206 through the bio-information database(www.Targetscan.org).Later,we explored the effects of microRNA-206 and its target genes on the proliferation,migration,and paracrine ability of senescent BMSCs.In vivo experiments,we constructed rat myocardial infarction(MI)model,and then injected PBS,BMSCs treated with H2O2 and BMSCs treated with H2O2+microRNA-206 inhibitor near the ligation site(3-4 sites/heart)in the free wall of the left ventricle.The cardiac EF and FS values of the rats were measured by echocardiography at 28 days after surgery.Thereafter,we sacrificed the rats to obtain heart tissus and performed H&E staining,masson's trichrome staining,immunochemistry staining to determine the curative effect of microRNA-206 modified BMSCs in the treatment of MI.Results:We found that microRNA-206 was up-regulated in H2O2-induced senescent BMSCs.Besides,down-regulation of microRNA-206 could alleviate the migration and paracrine ability impairment by modulating the target gene alkaline phosphatase(Alpl).In vivo assay,we demonstrated that senescent BMSCs with lower microRNA-206 expression exhibited enhanced therapy potential for treating MI.Conclusion:In summary,we demonstrated that microRNA-206/Alpl axis could protect BMSCs from oxidative stress induced senescence and the cascade migration and paracrine ability impairment,further improving its therapy potential in MI treatment.