Cardioprotective effects of redox regulator MnTnBuOE-2-PyP ⁵⁺ in myocardial ischemia/reperfusion injury

BACKGROUND: Myocardial infarction is a leading cause of death worldwide and occurs due to decrease or complete blockage of coronary blood flow. Re-establishment of blood flow after a brief period of ischemia is accompanied by exacerbation of the cardiomyocytes and its death, a phenomenon known as myocardial ischemia-reperfusion (I/R) injury. Much evidence suggests that oxidative stress is involved in the pathogenesis of myocardial ischemia-reperfusion injury and is potential target for therapeutic interventions. The aim of this study is to evaluate cardioprotective role of redox active Mn(III) N-n-butoxyethylpyridinium-2-yl)porphyrin, MnTnBuOE-2-PyP5+ (BMX-001) in myocardial I/R injury. This drug is now in 4 Phase II clinical trials where the radioprotection of normal issue and anticancer efficacy have been evaluated. METHODS: Myocardial I/R injury in mice C57BL/6 was induced by ligating left anterior descending artery for 1 hour followed by 24 hours of reperfusion. At the end of reperfusion, hearts were sectioned (1mm) and stained with 1% 2, 3, 5-Triphenyltetrazolium chloride (TTC) to determine infarct size. Cardiac function was evaluated by M-mode echocardiography at the end of the reperfusion. For in vitro model, H9c2 cells were subjected to hypoxia for 3 hours followed by 24 hours of reperfusion. Cell apoptosis was measured by TUNEL assay. Mitochondrial superoxide and Cardiolipin peroxidation were measured by using MitoSOX and 10-N-nonyl-Acridin Orange, respectively. RESULTS: In the current study, we demonstrated that treatment with MnTnBuOE-2-PyP5+ (2mg/kg) 4 hours before I/R injury in mice ameliorate cardiac injury as evident by limited infarct size and improved cardiac function (P<0.05). Consistently, MnTnBuOE-2-PyP5+ improved mitochondrial SOD2 expression (P<0.05) and reduced cardiomyocytes apoptosis in mice heart (P<0.05). In our in vitro model of hypoxia/reoxygenation injury in H9c2 cells, treatment with MnTnBuOE-2-PyP5+ (10µM) 24 hours before hypoxia/ reoxygenation injury decreased cardiolipin peroxidation, mitochondrial superoxide level and 4-HNE adducted proteins (P<0.01). Additionally we explored role of MnTnBuOE-2-PyP5+ on cell apoptosis following ischemia/reperfusion injury in H9c2 cells. Redox regulator significantly reduced TUNEL positive cells following I/R injury indicating reduced cardiomyocytes apoptosis (p<0.05). In-vitro, redox-active Mn porphyrin improved cell viability and lactate dehydrogenase release following hypoxia/reoxygenation in H9c2 cells (p<0.05). CONCLUSION: This result provided evidence that MnTnBuOE-2-PyP5+ elicited cytoprotective effects through reduction of mitochondrial oxidative stress and cardiomyocyte apoptosis suggesting prospective therapeutics in myocardial I/R Injury.

Duke Scholars

Author Ines Batinic-Haberle Radiation Oncology