Abstract 018: Rat Ckit+ Cardiac Progenitor Cells Release Pro-survival Micrornas In Exosomes Following Hypoxic Stimulation.
Introduction: Cardiovascular disease is the leading cause of morbidity and mortality among developed nations, and acute myocardial infarction is the major subgroup. The need exists for cardiac therapeutic systems that mitigate tissue damage and induce regeneration within and around the infarcted region. Cardiac progenitor cells (CPCs) and other stem cell types have been attractive candidates for therapies. However, results suggest that regenerative or protective effects may occur through paracrine mechanisms. One such way may be through cell-cell transfer of microRNA (miR) via cell-secreted exosomes, which contain protein, mRNA, and miR. Cell-based therapies face substantial limitations, and therapies avoid these limitations and mimic paracrine efforts—such as delivery of harvested exosomes—have yet to be developed due in part to lack of characterization.
Hypothesis: We hypothesized that in response to hypoxic conditions, CPCs secrete a pro-regenerative miRnome within exosomes.
Methods: We used an Affymetrix MicroRNA GeneChip microarray to identify the miR populations that were present in CPC-conditioned media after hypoxic and normoxic treatments. Exosomes were isolated via ultracentrifugation (100,000xG) and validated by anti-CD9 immunohistochemistry and dynamic light scattering. We used RT-qPCR to quantify levels of miR upregulation in secreted exosomes.
Results: We found seven miRs upregulated (1.3- to 7.9-fold) due to hypoxia stimulation. Within that miRnome, two miRs ([[Unable to Display Character: ‐]]20a, [[Unable to Display Character: ‐]]210) are known to exert cardioprotection in infarct models, providing evidence of a potential beneficial paracrine effect from CPCs. Four of the remaining miRs (-15b, -17, -103, -199a) have been shown to regulate angiogenesis, proliferation, apoptosis, and fibrosis in various cell and tissue types. One miR ([[Unable to Display Character: ‐]]292) has been largely unexplored, but predicted mRNA targets include CTGF, which is involved in cell adhesion and fibrosis.
Conclusions: The strong evidence of anti-apoptotic and anti-fibrotic potential of this miRnome indicates that the cocktail may serve as a powerful modulator of cardiac remodeling. Future work will investigate applying miR-containing exosomes from hypoxia-stimulated CPCs as a therapy to rescue the infarcted heart.
- © 2013 by American Heart Association, Inc.