Abstract 17373: MicroRNA-155 Over-expression Inhibits Angiogenesis Of Lin-/cd34+ Cells From Human CAD Patients and HUVECs
Introduction: In the cellular hypothesis of atherosclerosis, bone marrow (BM) derived EPCs contribute to vascular repair and regeneration, and defects in number and/or function of EPCs may contribute to the progression of atherosclerosis and coronary artery disease (CAD). Autologous stem cell therapy for CAD requires functionally competent EPCs. Micro-RNAs (miRs) have been implicated in the regulation of angiogenesis; miR-155 is activated by inflammatory cytokines.
Hypothesis: Dysregulated expression of miR-155 in response to an inflammatory environment within the BM of CAD patients causes functional defects in BM-derived EPCs that promote CAD progression and impairment of autologous stem cell therapy.
Objective: To quantify the level of miR-155 in EPCs from CAD patients and functionally characterize the effects of miR 155 over-expression on the angiogenic potential of Lin-/CD34+ cells and HUVECs.
Methods: BM was collected from 5 CAD, 4 non-CAD patients and healthy volunteers; Lin-/CD34+ cells were isolated and subjected to microarray and micro-RNA profiling. HUVECs were transfected with pre and anti-miRs of miR-155. HUVEC tube formation, proliferation and cell death were quantified. Protein and RNA were quantified by western blot and RT-PCR.
Results: Microarray and RT-PCR confirmed >5-fold up regulation of miR-155 in Lin-/CD34+ cells of CAD patients compared with non-CAD (p<0.05). MiR-155 knockdown in HUVECs increased HIF1alpha and CCND1 protein as measured by western blot (p<0.05). MiR-155 over-expression using precursor molecules significantly inhibited tube formation and cell proliferation of HUVECs (both p<0.01). LDH assay revealed an increase in cell death of HUVECs transfected with pre-miR-155 (p<0.05). The results are consistent with other studies showing that miR-155 regulates multiple biological processes including cell differentiation, survival, and cell migration and extrapolate this to suppression of angiogenesis.
Conclusion: The expression of miR-155 is markedly increased in CD34+/Lin- EPCs from patients with CAD. miR-155 over expression represses angiogenesis and may drive disease progression. Neutralization of miR-155 over-expression in EPCs is predicted to improve autologous stem cell therapy for CAD.
- © 2011 by American Heart Association, Inc.