Optimization of siRNA therapeutics targeting MIAT for cardioprotection in myocardial ischemia/reperfusion injury

Myocardial ischemia/reperfusion (MI/R) injury is a leading cause of heart failure, and novel therapeutic strategies are urgently needed to improve patient outcomes. Long non-coding RNA (lncRNA) myocardial infarction-associated transcript (MIAT) has been implicated in exacerbating myocardial damage during ischemia, making it an attractive target for RNA interference. In this study, we designed and optimized small interfering RNAs (siRNAs) to silence MIAT expression and evaluated their cardioprotective effects <i>in vitro</i> and <i>in vivo</i>. Through bioinformatics analysis, we identified conserved target sites within MIAT sequences across humans, rats, and mice. We demonstrated that siRNA targeting MIAT, particularly siMIAT-20mer-UU-3, significantly improved cell viability in human and rat myocardial cells subjected to hypoxia/reoxygenation (H/R) injury, with dose-dependent effects. Furthermore, siMIAT treatment alleviated key pathological processes, including calcium overload, oxidative stress, and mitochondrial dysfunction. In a rat MI/R model, siMIAT-20mer-UU-3 significantly reduced infarct size by 49.26%, stabilized cardiac function, and improved histopathological features. Transcriptomic analysis revealed that siMIAT modulated the cAMP/protein kinase A (PKA) and NADPH/reactive oxygen species (ROS) pathways, highlighting its role in restoring myocardial homeostasis. These findings provide strong evidence for the therapeutic potential of MIAT-targeting siRNAs in treating MI/R injury and offer a comprehensive approach to the development of RNA-based therapeutics for cardiovascular diseases.