Inhibition of 14q32 MicroRNAs miR-329, miR-487b, miR-494 and miR-495 Increases Neovascularization and Blood Flow Recovery after Ischemia
Rationale: Effective neovascularization is crucial for recovery after cardiovascular events.
Objective: As microRNAs regulate expression of up to several hundred target genes, we set out to identify microRNAs that target genes in all pathways of the multifactorial neovascularization process. Using www.targetscan.org, we performed a reverse target prediction analysis on a set of 197 genes involved in neovascularization. We found enrichment of binding sites for 27 microRNAs in a single microRNA gene cluster. MicroArray analyses showed upregulation of 14q32 microRNAs during neovascularization in mice following single femoral artery ligation.
Methods and Results: Gene Silencing Oligonucleotides (GSOs) were used to inhibit four 14q32 microRNAs, miR-329, miR-487b, miR-494 and miR-495, one day prior to double femoral artery ligation. Blood flow recovery was followed by Laser Doppler Perfusion Imaging. All 4 GSOs clearly improved blood flow recovery after ischemia. Mice treated with GSO-495 or GSO-329 showed increased perfusion already after 3 days (30% perfusion vs. 15% in control) and those treated with GSO-329 showed a full recovery of perfusion after 7 days (vs. 60% in control). Increased collateral artery diameters (arteriogenesis) were observed in adductor muscles of GSO-treated mice, as well as increased capillary densities (angiogenesis) in the ischemic soleus muscle. In vitro, treatment with GSOs led to increased sprout formation and increased arterial endothelial cell proliferation, as well as to increased arterial myofibroblast proliferation.
Conclusions: The 14q32 microRNA gene cluster is highly involved in neovascularization. Inhibition of 14q32 microRNAs miR-329, miR-487b, miR-494 and miR-495 provides a promising tool for future therapeutic neovascularization.
- Received July 3, 2014.
- Revision received July 30, 2014.
- Accepted August 1, 2014.