Abstract 572: Inhibition of MicroRNA-199a-5p Enhances Perfusion Recovery and Arteriogenesis Following Femoral Arterial Ligation

Abstract

We have recently reported that a subset of collateral artery segments in the mouse hindlimb are exposed to both a 2-fold increase in shear stress magnitude and reversed flow direction (“reversed” flow) following femoral arterial ligation (FAL). These segments experiencing a reversed flow subsequently undergo a disproportionate amplification of collateral growth (i.e. arteriogenesis) after FAL. Interestingly, a subset of microRNAs, including miR-199a-5p, are significantly down-regulated in endothelial cells exposed to a shear stress waveform biomimetic of this pro-arteriogenic “reversed flow” condition in-vitro. Here, we hypothesized that the inhibition of miR-199a-5p would lead to enhanced arteriogenesis and/or perfusion recovery following arterial occlusion. To test this hypothesis, Balb/c mice were treated with either anti-miR-199a-5p or non-targeting control locked-nucleic acid (LNA) immediately following FAL. Treatment efficacy was determined via RT-PCR for expression of miR-199a-5p and its downstream targets’ expression. Laser Doppler perfusion imaging and both whole mount and cross-sectional analysis of vascular casted gracilis muscles were used to assess vascular remodeling. We found that anti-miR-199a-5p LNA markedly reduced miR-199a-5p expression in the gracilis muscle by over 80%, 7 days post-FAL (n=4). By day 21 post-FAL, perfusion recovery was significantly improved in anti-miR-199a-5p treated mice (101.5±1.8% vs. 87.8±1.8%, p≤0.05, n=6). Moreover, both lumenal diameter (106.5±7.2μm vs. 78.4±2.9 μm, p≤0.0001, n=6) and wall area (1770±147μm 2 vs. 1163±41μm 2 , p≤0.0001, n=6) were significantly enhanced in anti-miR-199a-5p treated mice compared to controls. We therefore conclude that the inhibition of miR-199a-5p leads to enhanced perfusion recovery and arteriogenesis following arterial occlusion and could represent a novel strategy for therapeutic arteriogenesis.