Abstract 15431: Engineered Nanovesicles With Microrna-126 Cargo Improve Cardiac Repair After Myocardial Infarction in a Rat Ischemia-Reperfusion Model

Abstract

Introduction: Ckit+ progenitor cells (CPCs) produce small extracellular vesicles (sEVs) which are pivotal for CPC-based cardiac repair after myocardial infarction (MI). sEVs encapsulate potent RNA cargo within a bilayer membrane which aids with sEV uptake. However, despite established benefits, sEV therapies are limited by inconsistent sEV release from cells and variable cargo encapsulation. Further, although synthetic sEV mimics allow cargo tunability, they suffer rapid clearance when administered. We have developed an sEV-like vesicle (ELV) which maintains an sEV-like membrane, important for efficient uptake, but allows cargo control like that of sEV-mimics. We hypothesize that ELVs with proangiogenic microRNA (miR) cargo improve cardiac repair in a rat ischemia-reperfusion (IR) model compared to sEVs and that this occurs in a dose-dependent manner. Methods: sEVs were isolated from CPC conditioned media via ultracentrifugation and sEV inherent cargo was depleted with sonication. ELVs with miR-126 cargo were synthesized from sEVs using square-wave electroporation and characterized. miR-126+ELVs and sEVs (at 5 μg/kg or 10 μg/kg) were administered intramyocardially to the failing left-ventricle (LV) of Sprague Dawley rats after 30-minute IR injury. Infarct size was quantified with TTC/Evans blue staining after 24 hours. LV global and segmental hemodynamic parameters were assessed at baseline, Day 7, 14, and 28. After 28 days, LV fibrosis, hypertrophy and vessel formation were assessed with picrosirius red, wheat germ agglutinin and isolectin staining, respectively. Results: miR-126+ELVs were of similar size and concentration to CPC-sEVs. Upon administration, all groups reduced infarct size 24 hours post-treatment compared to IR-only. Further, ELV groups improved global hemodynamic parameters compared to controls with a dose-dependent segmental response across the LV. Finally, miR-126+ELVs increased vessel density compared to sEVs. Conclusion: ELVs with an sEV-like membrane but tailored cargo allow for cardiac repair after MI in a rat IR model, with both global and regional hemodynamic improvements and tunable histological responses. This work highlights the scope of miR+ELV therapies for cardiac diseases even beyond MI.