Hydrogen Peroxide Preconditioning Enhances The Therapeutic Efficacy Of Umbilical Cord Mesenchymal Stem Ceil Transplantation After Myocardial Infarction

Human umbilical cord Wharton's Jelly is an ideal alternative source formesenchymal stem cell (MSC). However, no study has reported transplantation ofMSC derived from Wharton's Jelly (WJ-MSC) for the treatment of ischemic heartdisease. Oxidative stress involves in the pathological process of myocardialinfarction (MI) and ischemia/reperfusion. Studies have shown that exposure tosublethal concentrations of hydrogen peroxide (H₂O₂) can alleviate subsequentoxidative stress-induced injuries of cells. Here we assessed the therapeuticefficacy of WJ-MSC and the effect of H₂O₂preconditioning on the therapeuticpotential of WJ-MSC in a mouse model of myocardial infarction.Firstly, we isolated WJ-MSC from fresh human umbilical cords and identifiedthe characterization. Mice underwent left anterior descending coronary artery(LAD) ligation, and received injection of150μl PBS (MI group, n=6),1×10⁶WJ-MSC (WJ-MSC group, n=6), or1×10⁶MSC derived from human bonemarrow (BM-MSC group, n=6)3h later via tail vein. The sham operated group(n=8) received either WJ-MSC or BM-MSC. Echocardiographic measurements at0,7,14, and28d revealed a significant improvement in the left ventricularcontractility of the WJ-MSC group compared to the MI group, as measured bydecreased LVESd (p<0.001), decreased LVEDd (p<0.05), and increased LVFS(p<0.001). Histological analysis revealed reduced collagen volume in theWJ-MSC group compared to MI group. There were no significant differencesbetween WJ-MSC group and BM-MSC group. Secondly, WJ-MSC were incubated in the media for2h with200μM H₂O₂.3hafter LAD ligation, mice received injection of PBS (MI group, n=8),1×10⁶WJ-MSC (WJ-MSC group, n=8), or1×10⁶H₂O₂preconditioned WJ-MSC(WJ-MSC-H₂O₂group, n=8) via tail vein. The sham operated group (n=8)received either WJ-MSC or WJ-MSC-H₂O₂. Transthoracic echocardiographyshowed that compared to the WJ-MSC group, WJ-MSC-H₂O₂transplantationmore markedly preserved cardiac function. Histological analysis revealedincreased neovascularization and reduced myocardial fibrosis in theWJ-MSC-H₂O₂group compared to the WJ-MSC group. In vitro, we measured theconcentrations of HGF, VEGF, IL-6and TNF-α in the cell culture supernatantusing ELISA. Pretreatment of WJ-MSCs with H₂O₂increased the concentration ofIL-6by approximately25-fold. Furthermore, the culture supernatant fromWJ-MSC-H₂O₂significantly increased the migration and proliferation ofendothelial cells in the Transwell migration and MTT assays; these effects couldbe partly blocked by an anti-IL-6antibody.This study demonstrates that WJ-MSC transplantation can well preservecardiac function after MI. H₂O₂preconditioning can enhance the therapeuticpotential of WJ-MSC, possibly by stimulating the production of IL-6by WJ-MSC,which may cause migration of endothelial cells to ischemic myocardium andstimulate endothelial cells proliferation and neovascularization. From a clinicalperspective, H₂O₂preconditioning may provide a simple and effective strategy toincrease the therapeutic efficiency of MSC-based treatments for MI.