Magnesium lithospermate B enhances the potential of human-induced pluripotent stem cell-derived cardiomyocytes for myocardial repair

Background:We previously reported that activation of the cell cycle in human-induced pluripotent stem cell-derived cardiomyocytes(hiPSC-CMs)enhances their remuscularization capacity after human cardiac muscle patch transplantation in infarcted mouse hearts.Herein,we sought to identify the effect of magnesium lithospermate B(MLB)on hiPSC-CMs during myocardial repair using a myocardial infarction(MI)mouse model.Methods:In C57BL/6 mice,MI was surgically induced by ligating the left anterior descending coronary artery.The mice were randomly divided into five groups(n=10 per group);a MI group(treated with phosphate-buffered saline only),a hiPSC-CMs group,a MLB group,a hiPSC-CMs+MLB group,and a Sham operation group.Cardiac function and MLB therapeutic efficacy were evaluated by echocardiography and histochemical staining 4 weeks after surgery.To identify the associated mechanism,nuclear factor(NF)-κB p65 and intercellular cell adhesion molecule-1(ICAM1)signals,cell adhesion ability,generation of reactive oxygen species,and rates of apoptosis were detected in human umbilical vein endothelial cells(HUVECs)and hiPSC-CMs.Results:After 4 weeks of transplantation,the number of cells that engrafted in the hiPSC-CMs+MLB group was about five times higher than those in the hiPSC-CMs group.Additionally,MLB treatment significantly reduced tohoku hospital pediatrics-1(THP-1)cell adhesion,ICAM1 expression,NF-κB nuclear translocation,reactive oxygen species production,NF-κB p65 phosphorylation,and cell apoptosis in HUVECs cultured under hypoxia.Similarly,treatment with MLB significantly inhibited the apoptosis of hiPSC-CMs via enhancing signal transducer and activator of transcription 3(STAT3)phosphorylation and B-cell lymphoma-2(BCL2)expression,promoting STAT3 nuclear translocation,and downregulating BCL2-Associated X,dual specificity phosphatase 2(DUSP2),and cleaved-caspase-3 expression under hypoxia.Furthermore,MLB significantly suppressed the production of malondialdehyde and lactate dehydrogenase and the reduction in glutathione content induced by hypoxia in both HUVECs and hiPSC-CMs in vitro.Conclusions:MLB significantly enhanced the potential of hiPSC-CMs in repairing injured myocardium by improving endothelial cell function via the NF-κB/ICAM1 pathway and inhibiting hiPSC-CMs apoptosis via the DUSP2/STAT3 pathway.

Antioxidant properties of magnesium lithospermate B contribute to the cardioprotection against myocardial ischemia/reperfusion injury in vivo and in vitro

OBJECTIVE： To determine the cardioprotective ef- fect of magnesium lithospermate B （MLB） on myo- cardial ischemia/reperfusion （MI/R） injury and to in- vestigate the antioxidant potential in vivo and in vitro. METHODS： MI/R injury was induced by the occlu- sion of left anterior descending coronary artery for 30 min followed by reperfusion for 3 h in rats. After reperfusion, hearts were harvested to assess infarct size, histopathological damages, the levels of superoxide dismutase （SOD）, catalase （CAT）, glutathione peroxidase （GPx）, reduced glutathione （GSH） and malondialdehyde （MDA）. Blood samples were collected to determine serum levels of creatine kinase-MB （CK-MB）, cardiac troponin （cTnl） and lactate dehydrogenase （LDH）. Furthermore, simulatedischemia/reperfusion （SI/R） injury in vitro was established by oxygen and glucose deprivation （OGD） for 2 h followed by 24-hour recovery period in cardiomyocytes. The activity of LDH in the cultured su- pernatant and the levels of intracellular reactive oxygen species （ROS）, SOD and MDA in cardiomyo- cytes were also measured. Finally, cardiomyocytes apoptosis was determined with flow cytometry. RESULTS： MLB significantly limited infarct size, ameliorated histopathological damages and prevented leakage of CK-MB, cTnl and LDH. Additional- ly, SOD, CAT, GPx and GSH activities were notably increased by MLB, along with the MDA content decreased as compared with the model group in rats. In vitro study, MLB also decreased LDH activity in the cultured supernatant, increased SOD activity in cardiomyocytes, reduced intracellular ROS and MDA levels, and significantly suppressed cardiomyocytes apoptosis. CONCLUSION： MLB possessed remarkably cardioprotective effects on MI/R injury in vivo and in vitro. The protection of MLB may contribute to its antioxidant properties.