Abstract 17202: Synthetic Modified RNA Driven Delivery of Insulin-Like Growth Factor-1 Promotes Early Cardiomyocyte Survival Post-Acute Myocardial Infarction

Abstract

To extend the temporal window for cytoprotection in cardiomyocytes undergoing apoptosis after hypoxia and myocardial infarction (MI), a synthetic modified RNA (modRNA) was used to drive delivery of insulin-like growth factor-1 (IGF1) within the area at risk in a murine model of MI. Transient transfection of synthetic GFP modRNA as an tracking indicator, with polyethylenimine (PEI)-based nanoparticle, showed efficient delivery of modRNA derived protein and minimum cytotoxicity in HL-1 cardiomyocytes (CM; 44±5%). ModRNA-IGF1 protein expression and secreted levels increased 3.5 fold ( p <0.05) at 24 hours and peaked at 48 hours post-transfection. The expression efficiency of modRNA was further enhanced (~2 fold at 24 hours post-transfection; p <0.05) under hypoxia-induced apoptosis conditions. ModRNA augmented secreted and cell associated IGF1 promoting CM survival and abrogating cell apoptosis (71±5% in controls to 37±7%, p <0.05). Translation of modRNA-IGF1 was sufficient to induce downstream increases in Akt and Erk phosphorylation (3 fold and 2 fold, respectively; p <0.01). Downregulation of IGF1 specific miRNA-1 and -133 (52% and 56%, respectively; p <0.01) but not miR-145 expression, was also confirmed. As proof of concept, intramyocardial delivery of modRNA-IGF1 but not control modRNA-GFP significantly decreased in TUNEL-positive cells within the infarct border zone (BZ) at 24 hours (22±3% versus 53±8% in controls, p <0.01). Akt phosphorylation was augmented while caspase-9 activity and cleavage was downregulated in the infarct BZ compared to controls ( p <0.05). These findings demonstrate extended in vivo cytoprotective effect of IGF1 24 hours post-MI driven by synthetic modRNA delivery. This provides a novel strategy to reduce ischemic injury by controlled release of IGF1 using a controllable bioactive nanoparticle for ‘short burst’ IGF1 cytoprotective therapy.