Abstract 15845: Intracoronary Delivery of Exosomes Secreted by Cardiosphere-Derived Cells Confers Cardioprotection wWth Delayed Administration After Ischemia-Reperfusion Injury in Rats
Introduction: Cardiosphere-Derived Cells (CDCs) exert both regenerative and cardioprotective effects following ischemic insult to the myocardium despite limited cell engraftment. Here we demonstrate that exosomes (30-150nm lipid bilayer vesicles) secreted from human CDCs (hCDCs) confer a dose-dependent reduction in infarct size and preservation of cardiac function when infused into the coronary circulation in rats following ischemia/reperfusion (IR) injury.
Methods & Results: To examine the safety and efficacy of CDC-exosomes (EXOCDC), we performed a dose-finding study in Wistar-Kyoto rats (WKY; aged 8-12 weeks). Briefly, conditioned media was collected from hCDCs grown in serum-free media for 4 days then EXOCDCs were precipitated using ExoQuick-TC (SBI). As a starting dose, EXOCDCs were isolated from an equivalent, and previously-validated, CDC dose for intracoronary delivery following IR (3mL/3x105 CDCs). EXOCDC protein quantity was determined (~700ug/10mL) and doses were titrated. For in vivo analyses, WKY rats underwent 45 minutes of ischemia followed by 20 minutes of reperfusion. Animals were then randomly allocated to receive either PBS or a titrated dose of EXOCDC (derived from 10mL, 3mL, or 1mL CDC-conditioned media). Two days following injury, all EXOCDC doses (10mL, 3mL, and 1mL) conferred a significant reduction in percent infarct mass relative to PBS control (PBS: 13.56% vs. 10mL: 6.38%; 3mL: 6.94%; 1mL: 8.03% p<0.05). Similarly, ejection fraction was preserved in the lower doses (PBS: 43.07% vs. 10mL: 57.40%; 3mL: 58.17%; 1mL: 55.49%; p<0.05). Interestingly, these EXOCDC express a unique surface protein signature comprising some generic markers from exosomes (CD63, HSP70, but not CD9 or CD81) as well as CDC-specific markers (CD105).
Conclusions: Cell-free EXOCDC, delivered via the intracoronary route 20 min post-IR, are cardioprotective. The evaluation of efficacy at 48 hours rules out regenerative effects, which become manifest over weeks. The ability to delay administration after IR renders the protocol clinically-realistic. Thus, EXOCDC may be useful cardioprotective therapeutic candidates adjunctive to routine therapy for myocardial infarction.
Author Disclosures: G. de Couto: None. P. Durvasula: None. A. Ibrahim: None. E. Marbán: Ownership Interest; Significant; Capricor Inc..
- © 2014 by American Heart Association, Inc.