Y RNA fragment in extracellular vesicles confers cardioprotection via modulation of IL‐10 expression and secretion

Cardiosphere‐derived cells (CDCs) reduce myocardial infarct size via secreted extracellular vesicles (CDC‐EVs), including exosomes, which alter macrophage polarization. We questioned whether short non‐coding RNA species of unknown function within CDC‐EVs contribute to cardioprotection. The most abundant RNA species in CDC‐EVs is a Y RNA fragment (EV‐YF1); its relative abundance in CDC‐EVs correlates with CDC potency in vivo . Fluorescently labeled EV‐YF1 is actively transferred from CDCs to target macrophages via CDC‐EVs. Direct transfection of macrophages with EV‐YF1 induced transcription and secretion of IL‐10. When cocultured with rat cardiomyocytes, EV‐YF1‐primed macrophages were potently cytoprotective toward oxidatively stressed cardiomyocytes through induction of IL‐10. In vivo, intracoronary injection of EV‐YF1 following ischemia/reperfusion reduced infarct size. A fragment of Y RNA, highly enriched in CDC‐EVs, alters Il10 gene expression and enhances IL‐10 protein secretion. The demonstration that EV‐YF1 confers cardioprotection highlights the potential importance of diverse exosomal contents of unknown function, above and beyond the usual suspects (e.g., microRNAs and proteins). Synopsis A Y RNA fragment enriched in extracellular vesicles from cardiosphere‐derived cells was identified and found to increase IL‐10 expression and secretion in macrophages. The fragment confers cardioprotection after ischemic injury in a rat model. A Y RNA fragment is the most abundant small RNA species in extracellular vesicles secreted from cardiosphere‐derived cells. When overexpressed in macrophages, this Y RNA fragment increases Il‐10 gene expression and secretion of IL‐10 protein, rendering macrophages cardioprotective. When administrated in a rat model of myocardial infarction, this Y RNA fragment confers cardioprotection. Graphical Abstract A Y RNA fragment enriched in extracellular vesicles from cardiosphere‐derived cells was identified and found to increase IL‐10 expression and secretion in macrophages. The fragment confers cardioprotection after ischemic injury in a rat model.