MicroRNA-15a and MicroRNA-16 Impair Human Circulating Pro-Angiogenic Cell (PAC) Functions and are Increased in the PACs and Serum of Patients with Critical Limb Ischemia
Rationale: Circulating Proangiogenic Cells (PACs) support post-ischemic neovascularization. Cardiovascular disease and diabetes impair PAC regenerative capacities via not fully known molecular mechanisms. We hypothesize a role for microRNAs (miRs). Circulating miRs are currently investigated as potential diagnostic and prognostic biomarkers.
Objective: 1) To profile miR expression in PACs from critical limb ischemia (CLI) patients; 2) To demonstrate that miR-15a and miR-16 regulate PAC functions; 3) To characterize circulating miR-15a and miR-16 and to investigate their potential biomarker value.
Methods and Results: Twenty-eight miRs potentially able to modulate angiogenesis were measured in PACs from CLI patients with/out diabetes and controls. miR-15a and miR-16 were further analyzed. CLI-PACs expressed higher level of mature miR-15a and miR-16 and of the primary transcript primiR-15a/16-1. miR-15a/-16 overexpression impaired healthy PACs survival and migration. Conversely, miR-15a/-16 inhibition improved CLI-PAC defective migration. VEGF-A and AKT-3 were validated as direct targets of the two miRs and their protein levels were reduced in miR-15a/-16-overexpressing healthy PACs and in CLI-PACs. Transplantation of healthy PACs ex-vivo engineered with anti-miR-15a/-16 improved post-ischemic blood flow recovery and muscular arteriole density in immunodeficient mice. miR-15a and miR-16 were present in human blood, including conjugated to Argonaute-2 and in exosomes. Both miRs were increased in the serum of CLI patients and positively correlated with amputation after restenosis at 12 months post-revascularization of CLI-T2D patients. Serum miR-15a additionally correlated with restenosis at follow-up.
Conclusions: 1) Ex-vivo miR-15a/16 inhibition enhances PAC therapeutic potential; 2) circulating miR-15a deserves further investigation as prognostic biomarker in CLI patients undergoing revascularization.
- pro-angiogenic cells (PACs)/endothelial progenitor cells (EPCs)
- peripheral vascular disease
- progenitor cell
- diabetes mellitus
- Received November 1, 2012.
- Revision received November 30, 2012.
- Accepted December 11, 2012.
- Copyright © 2012, Circulation Research