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

Poster Board Number: E38

Sudha Sharma (Louisiana State University Health Sciences Center), Foram Patel (Louisiana Tech University), Susmita Bhattarai (Louisiana State University Health Sciences Center), Hosne Ara (Louisiana State University Health Sciences Center), Utsab Subedi (Louisiana State University Health Sciences Center), Md. Shenuarin Bhuiyan (Louisiana State University Health Sciences Center), Ines Batinic-Haberle (Duke University), Manikandan Panchatcharam (Louisiana State University Health Sciences Center), Sumitra Miriyala (Louisiana State University Health Sciences Center)

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 (Plt;0.05). Consistently, MnTnBuOE-2-PyP5+ improved mitochondrial SOD2 expression (Plt;0.05) and reduced cardiomyocytes apoptosis in mice heart (Plt;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 (Plt;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 (plt;0.05). In-vitro, redox-active Mn porphyrin improved cell viability and lactate dehydrogenase release following hypoxia/reoxygenation in H9c2 cells (plt;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.

110101074A HL141998 and HL141998-01S1, P20GM121307 AA025744, AA026708, and AA025744- 02S1 AA023610 to HS, HL122354 and HL145753, Malcolm Feist Predoctoral fellowship to Sudha Sharma.