Abstract 17184: Exosomes From iPSC-Derived Cardiomyocytes Restore the Injured Murine Myocardium
Background: Pluripotent stem cell-derived cardiomyocytes (iCMs) represent a potential therapeutic to restore the injured myocardium; however, little is known about the underlying mechanism of action. Longitudinal studies of iCMs to treat myocardial injury (MI) show low engraftment despite significant functional restoration. Studies from our group demonstrated that the iCM secretome contains cardioprotective factors to restore the injured myocardium. We propose that the putative effects of iCMs are mediated by exosomes, which are enriched in cardioprotective microRNAs (miRNAs), to modulate the gene expression in the recipient cardiomyocytes and salvage the peri-infarct region.
Methods: Serum-free supernatant of the contractile iCMs was collected. Exosomes were isolated by PEG precipitation and verified by CD63 immunoblotting and Nanosight. MiRNA cargo was detected by microarray and qRT-PCR. The resultant miRNA regulatory networks were determined by Affymetrix Expression Console and Ingenuity Pathway Analysis software. Severe combined immune deficiency (SCID) mice underwent left anterior descending artery ligation and were injected with iCM exosomes or saline (control) in the peri-infarct region. Gene expression in the peri-infarct myocardium at week 4 was examined by qRT-PCR. MRI assessed myocardial viability, left ventricular volumes, and ejection function (LVEF) at two and four weeks post-MI.
Results: iCM exosomes were enriched in miRNAs involved in proliferation, cardiac hypertrophy, and hypoxia signaling pathways (miR-19, -24, -214, -92a-3p, -1246, -3665, -3960). Modulation of downstream gene expression of these pathways was seen in the injured murine myocardium. MLC2v, VEGF and TGF-b gene was up-regulated while collagen 3 and fibronectin were down-regulated. The exosome- vs. control-treated mice had significantly improved LVEF (week 2: 34.4±6.6%* vs. 24.1±5.9% and week 4: 35.7±4.1%* vs. 19.8±5.7%; p<0.01) and enhanced myocardial viability (week 2: 65.6±8.0% vs. 58.9±10.1% and week 4: 76.7±6.6%* vs. 46±8.4%; *p<0.01).
Conclusion: Exogenous administration of iCM-derived exosomes restores the injured myocardium. The cardioprotective miRNA cargo may underlie the mechanism of action.
Author Disclosures: M. Santoso: None. A. Tachibana: None. J. Jung: None. R.G. Sierra: None. A.B. Goldstone: None. B.B. Edwards: None. S. Wakatsuki: None. J. Woo: None. P.C. Yang: None.
- © 2016 by American Heart Association, Inc.