Abstract 18804: A Saline Containing Charge-Stabilized Nanostructures Inhibits Apoptosis of Cardiomyocytes Subjected to Ischemia/Reperfusion Injury

Background: Inflammation and apoptosis contribute to ischemia/reperfusion (I/R) injury after acute myocardial infarction (AMI). RNS60 is an isotonic saline solution containing charged-stabilized nanostructures introduced by Taylor-Couette Poiseuille flow in the presence of an elevated oxygen concentration. RNS60 has shown anti-inflammatory and cytoprotective effects across models of pulmonary and neuro-inflammation and significantly reduced infarct size in a pig model of AMI. Objective: To investigate whether RNS60 reduces tissue damage after AMI by effects on cardiomyocyte apoptosis. Methods: Groups of male pigs (25-35 kg) were subjected to myocardial ischemia for 60 minutes and treated with RNS60 or normal saline (NS) by single intracoronary injection (0.1 mL/kg) at time of reperfusion and by continuous intravenous infusion (1.0 mL/kg/hour) for 4 days. Apoptosis in the peri-infarct region was quantified by counting the number of caspase 3-positive cells. The expression of proteins of the reperfusion injury salvage kinase pathway was measured by Western blot. Results: Ischemia for 60 minutes followed by reperfusion for 4 days caused infarcts measuring 44% 6% of the area at risk in NS-treated animals (n=14). RNS60 treatment reduced the infarct size by 32 % (n=13, P <0.001). The number of caspase 3-positive cells in the peri-infarct region was significantly reduced in the RNS60-group ( P <0.05). At 4 days after reperfusion, the expression of phospho-Akt, Bcl-2, Bcl-xl, and phospho-GSK3 was not different between the groups. Interestingly, however, RNS60 treatment significantly reduced the expression of HSP90 ( P <0.01), which has recently been linked to a reduction of I/R injury by post-conditioning in pig hearts. Conclusion: Treatment with RNS60, a physically modified saline devoid of an active pharmaceutical ingredient, reduces I/R injury in a pig model of AMI, at least in part through inhibition of apoptosis and modulation of the stress protein response in cardiomyocytes. These findings suggest the possibility to develop a new class of therapeutics to limit cardiac damage after coronary revascularization procedures in AMI patients.