Preventing pathological angiogenesis in the retina using a microRNA that regulates endothelial cell survival

Abstract

Purpose : Hypoxic stress induces pathological angiogenesis in neovascular retinal diseases. Targeting central signaling molecules that regulate sprouting endothelial cell survival represents a promising therapeutic approach for these diseases. We previously reported that microRNA-34-5p (miR-34-5p) is an important survival factor for isolated endothelial cells. In this study, we examine the effects of miR-34a-5p modulators (mimics and inhibitors) on vascular stability during development (hyaloid regression) and pathologic angiogenesis (oxygen-induced retinopathy; OIR) in mice.

Methods : Postnatal day 11 (P11) pups were injected intravitreally with miR-34-5p mimics or inhibitors. Hyaloidal vasculature was visualized by fluorescein angiography and branching points were quantified at P14. miR-34 modulators were also injected in OIR mice at P12 and the area of neovascularization (NV) and vaso-obliteration (VO) was quantified at P17. Fluorescent-tagged miR-34a oligonucleotides were injected to identify miR-34a target cells. Retinal flat mounts were examined 1 to 5 days post injection, and electroretinography (ERG) was performed 6 weeks post injection to examine the effects of miR-34a modulators on established vascular and neuronal networks.

Results : Hyaloid regression was significantly accelerated by injecting miR-34a-5p mimics while anti-miR-34a-5p delayed hyaloid regression significantly. In OIR mice miR-34a-5p mimics improved the vascular phenotype at OIR P17 by reducing retinal NV by 50% (p=0.005) and decreasing the VO area by 20% (p=0.04). Following intravitreal injection, fluorescent-tagged miR-34 oligonucleotides localized specifically to the hyaloid vasculature and pre-retinal tufts. ERGs and retinal morphology recorded 6 weeks post injection with miR-34a-5p mimics were normal.

Conclusions : miR-34a-5p is a potent mediator of vascular endothelial cell proliferation and apoptosis. miR-34a-5p modulators can effectively enhance or delay vascular regression and pathologic vaso-proliferation in vivo without eliciting vision threatening effects on established vascular or neuronal networks. Therefore, miR-34a mimics and inhibitors may have therapeutic potential for either stabilizing normal vessels or accelerating the clearance of regressing vascular networks depending on the specific stages of disease.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.