Abstract 16109: A Selective Cargo of Non-coding RNAs Mediate Therapeutic Potential of Human CD34+ Stem Cell-derived Exosomes
Introduction: Clinical application of human CD34+ stem cells is associated with improved exercise tolerance and therapeutic angiogenesis in patients with myocardial ischemia. We reported the first description of independent therapeutic potential of CD34+ stem cell-derived exosomes (CD34Exo) to that of parent cell by mechanisms that still remain poorly understood.
Hypothesis: Herein, we tested the hypothesis that CD34Exo may selectively carry non-coding RNA (ncRNA) cargo targeted for pro-angiogenic signaling and ischemic tissue repair.
Methods and Results: Murine models of myocardial ischemia employed throughout the study. Cell-free CD34Exo replicated the therapeutic activity of their parent cells by significantly improving myocardial ischemia (ejection fraction, 42±4 v 22±6%; capillary density, 113±7 v 66±6/HPF; fibrosis, 27±2 v 48±7%; p<0.05, n=7-12) compared with a PBS control. Confocal imaging and flow cytometry analyses revealed that CD34Exo was selectively internalized into endothelial cells and cardiomyocytes in the CD34Exo-injected ischemic hearts. MicroRNA (miR) profiling identified several pro-angiogenic miRs including miR-126 that are selectively enriched in CD34Exo. Mice injected with CD34Exo show elevated miR-126 and several pro-angiogenic mRNAs in ischemic myocardium, however did not affect endogenous miR-126 synthesis suggestive of direct CD34Exo-mediated miR-126 transfer. Depletion of miR-126 reduced the therapeutic efficacy of CD34Exo both in vitro and in vivo indicating a critical role for miR-126. Using fluorescent-tagged miR-126, we monitored in real-time the uptake and transfer of miR-126 by endothelial cells both in vitro and in vivo. We finally provide novel insights underlying CD34Exo function in regulating endothelial proliferation through identification of novel pathways regulated by miR-126 in endothelial cells.
Conclusion: Our results reveal specific CD34Exo-shuttled microRNAs and pathways regulated in the ischemic myocardium. Our work presents a molecular framework for CD34Exo mechanism and function in therapeutic angiogenesis. Precise understanding of CD34Exo mechanisms could significantly amplify the therapeutic benefits of CD34Exo in ischemic tissue regeneration and repair.
Author Disclosures: P. Mathiyalagan: None. Y. Liang: None. D. Kim: None. D.W. Losordo: None. R.J. Hajjar: None. S. Sahoo: Research Grant; Significant; AHA-SDG, NIH R01.
- © 2015 by American Heart Association, Inc.