Abstract 15125: Myocardial Protection from Ischemia-Reperfusion Injury by a Novel Necrosis Inhibitor (NecroX): In vitro and in vivo Study
Background: A novel necrosis inhibitor (NecroX) blocks the opening of mitochondrial permeability transition pore, consequently inhibits necrosis which is the main pathophysiology of ischemia-reperfusion (IR) injury. This study investigated the effect of NecroX on infarct size reduction through inhibition of necrosis, not apoptosis, in vitro and in vivo IR injury model.
Methods: In vitro study, H9C2 cells were incubated in hypoxic condition, followed by oxidative stress with pretreatment of NecroX or 0.01% DMSO. The cells were stained by FDA or mitotracker with PI and necrotic cells were counted by FACS. In vivo rat model was obtained by ligation of LAD for 45 minutes followed by reperfusion and 5% dextrose or 5.0 mg/kg of cyclosporine A (CsA) or 0.3 mg/kg of NecroX was injected intravenously 5 minutes before reperfusion. Necrosis area was measured at 12 hours after IR injury, using anti-myosin heavy chain antibody. Echocardiography was performed at baseline, 3rd, 7th, and 14th day, and myocardial fibrosis area was measured at 14th day.
Results: The necrosis inhibitor significantly reduced necrotic cells in IR injury model of H9C2 cells (14.1±1.8% [NecroX] vs. 43.9±3.2% [DMSO]; P<0.01). Mitotracker/PI staining showed swollen mitochondria with extensive cell necrosis in DMSO group, in contrast to the intact mitochondria without necrotic cells in NecroX group. Necrosis area measured at 12 hours after IR injury was significantly lower (1.5±1.0% [NecroX] vs. 9.0±4.5% [CsA] vs. 16.5±5.0% [dextrose]; P<0.01). In echocardiography, LV systolic function was preserved (LVEF at 14th day; 56.5±1.4% [NecroX] vs. 48.2±1.2% [CsA] vs. 46.8±1.4% [dextrose]; P<0.01), while remodeling was attenuated (LVESD at 14th day; 4.7±1.4 mm [NecroX] vs. 5.3±0.5 mm [CsA] vs. 5.6±1.9 mm [dextrose]; P<0.01). Also, myocardial fibrosis area was smallest (4.5±1.5% [NecroX] vs. 18.5±2.5% [CsA] vs. 25.5±3.0% [dextrose]; P<0.01). By administration of various dosages, we found a minimal effective dose of NecroX.
Conclusion: A novel necrosis inhibitor (NecroX) suppressed cell necrosis through inhibition of mitochondrial swelling in vitro and reduced myocardial infarct size in vivo IR injury model.
- © 2012 by American Heart Association, Inc.