Abstract 11511: Stem Cell-Derived Exosome Nebulization Therapy (SCENT) Promotes Cardiac Repair After Myocardial Infarction by Inhibiting CD36

Introduction: Stem cell-derived exosomes are promising therapeutics for cardiac repair after injury. Since they have short half-life in vivo, efficient exosome therapies need repeated dosing. Here, we develop a noninvasive and repeatable method for exosome delivery via a nebulizer after myocardial infarction (MI), named Stem Cell-Derived Exosome Nebulization Therapy (SCENT). Methods: Lung spheroid cell-derived-exosomes were isolated from secretome by ultrafiltration and characterized by a Zetasizer. We labelled them with a NIR-680 dye, before delivering them to C57BL/6 mice with MI model via a nebulizer for 7 consecutive days. IVIS live imaging and fluorescent microscopy was used to detect the biodistribution of exosomes in vivo and ex vivo. Echocardiographies were performed to monitor the cardiac function after SCENT in MI mouse and histological analysis helped investigating the myocardial repair, in comparison with the controls. Single-cell sequencing of the whole heart was performed to explore the mechanism of action after SCENT. Results: Homing of exosomes to the ischemic heart after SCENT was detected by immunofluorescence microscopy (Fig. 1a). SCENT led to significantly improved left ventricular function to our mouse MI model at 2 weeks (EF: 66.97 ± 2.49%), compared to that of MI control (EF: 36.13 ± 3.57%) (Fig. 1b) , along with reduced infarct size (Fig. 1c). Single-cell sequencing revealed a significant downregulation of CD36 in cardiac endothelial cells, which suppressed the transport and uptake of fatty acids in myocardium, leading to a compensatory increase in glucose utilization and cardiomyocyte proliferation (Fig. 1d,e) . Conclusions: Exosomes delivered by SCENT were recruited to the ischemic heart, which promoted function recovery and cardiac repair in a mouse MI model. This therapeutic effect was attributed to the inhibition of endothelial CD36. SCENT gives a promising solution for the repeatable and noninvasive treatment for heart repair.