Abstract Background Acute myocardial infarction (AMI) is one of the leading causes of death worldwide, however, there is still no clinically approved drug that effectively protects the heart during ischemia-reperfusion (I/R) injury. Such potential drugs could be microRNAs (miRNAs), which are small, non-coding RNA molecules, that play a key role in post-transcriptional gene regulation. We identified cardioprotective miRNA candidates termed ProtectomiRs in a translational porcine model of AMI. Among them, miR-450a was selected for further development. Purpose Here, we aimed to validate the cardiocytoprotective effect of miR-450a across species and explore the potential molecular mechanism of its action. Methods ProtectomiR candidates were identified in a translational porcine model of AMI and validated in neonatal rat cardiomyocytes and human AC16 cells under simulated I/R conditions. The effect of miR-450a mimic was assessed in different concentrations (25-100 nM) using cell viability measurements. To find the most appropriate dose for in vivo testing, miR-450a was further validated in lower concentrations as well (0.75-12.5 nM). Target genes of miR-450a were predicted by miRNAtarget™ software and pathways were analysed by KEGG and GO enrichment. Results Dose-response of miR-450a showed a bell-shaped curve, with 3.125 and 25 nM significantly enhanced cell viability in both cell culture models under simulated I/R. The predicted strongest target genes of miR-450a include SMAD family member 2 (SMAD2), death associated protein kinase 2 (DAPK2), superoxide dismutase 2 (SOD2), which are involved in TGFß signalling, apoptosis and redox regulation, respectively. GO and KEGG pathway analysis revealed mTOR and phosphatidylinositol signalling pathways which contribute to the cardioprotective effect of miR-450a. Conclusions MiR-450a represents a promising therapeutic candidate, exerting cardiocytoprotective effects in both rat and human cardiomyocytes through the regulation of gene network implicated in multiple cardioprotective signalling pathways. These findings suggest that miR-450a ProtectomiR is a potential lead molecule for the development of novel cardioprotective interventions.
Szabo et al. (Fri,) studied this question.