Abstract 11255: Adenosine Stimulates the Migration of Human Endothelial Progenitor Cells through Regulation of miR-150 and CXCR4
Purpose: Endothelial progenitor cells (EPC) represent a promising option to regenerate the infarcted myocardium. This therapy is limited by the number of cells recruited to injured sites. Mobilization of EPC from the bone marrow and migration are mainly under the control of the chemokine stromal cell-derived factor 1α (SDF-1α), which binds to the cell surface receptor CXCR4. Adenosine is pro-angiogenic but its effect on CXCR4 is unknown. Therefore, we determined whether adenosine affects the CXCR4-SDF-1α pathway.
Methods: EPC were obtained from peripheral blood mononuclear cells of healthy volunteers seeded onto human fibronectin-coated plates and cultured in endothelial cell-specific medium for 4 days. Expression of chemokines and their receptors was evaluated using microarrays and quantitative PCR. Cell surface expression of CXCR4 was assessed by flow cytometry. A modified Boyden chamber assay was used to measure the migration of EPC.
Results: Microarrays and PCR experiments showed that adenosine increased CXCR4 mRNA expression (3-fold, P<0.001). Cell surface expression of CXCR4 was also increased. Expression of miR-150, a microRNA known to regulate CXCR4 expression, was decreased (2-fold, P<0.001). We determined that EPC express A3, A2A and A2B adenosine receptors. Using pharmacological inhibitors of signaling pathways and RNA interference, we identified the A2B receptor as mediator of the effect of adenosine on CXCR4. EPC migration towards recombinant SDF-1α or conditioned medium from human primary cardiac fibroblasts was enhanced by pre-incubation of the cells with 10µmol/L adenosine. This effect was abolished by pre-incubation with anti-CXCR4 blocking antibodies. Adenosine also increased CXCR4 under ischemic conditions, and decreased miR-150 expression. Binding of miR-150 to the 3’ untranslated region of CXCR4 was verified by luciferase assay.
Conclusion: Adenosine increases the migration of EPC through decreased expression of miR-150 and increased expression of CXCR4. These results suggest that adenosine may be used to enhance the capacity of EPC to revascularize the ischemic heart.
- © 2012 by American Heart Association, Inc.