Activated Protein C (APC) and 3K3A-APC-Induced Regression of Choroidal Neovascularization (CNV) Is Accompanied by Vascular Endothelial Growth Factor (VEGF) Reduction.

Tami Livnat,John H Griffin,Dov Weinberger,José A Fernández,Gili Kenet,Alaa Bashir,Gil Ben-David,Sarina Levy-Mendelovich,Yael Nisgav,Ivan Budnik,Yehonatan Weinberger,Dahlia Palevski

doi:10.3390/biom11030358

Abstract

The activated protein C (APC) ability to inhibit choroidal neovascularization (CNV) growth and leakage was recently shown in a murine model. A modified APC, 3K3A-APC, was designed to reduce anticoagulant activity while maintaining full cytoprotective properties, thus diminishing bleeding risk. We aimed to study the ability of 3K3A-APC to induce regression of CNV and evaluate vascular endothelial growth factor (VEGF) role in APC’s activities in the retina. CNV was induced by laser photocoagulation on C57BL/6J mice. APC and 3K3A-APC were injected intravitreally after verification of CNV presence. CNV volume and vascular penetration were evaluated on retinal pigmented epithelium (RPE)-choroid flatmount by fluorescein isothiocyanate (FITC)-dextran imaging. VEGF levels were measured using immunofluorescence anti-VEGF staining. We found that 3K3A-APC induced regression of pre-existing CNV. VEGF levels, measured in the CNV lesion sites, significantly decreased upon APC and 3K3A-APC treatment. Reduction in VEGF was sustained 14 days post a single APC injection. As 3K3A-APC retained APCs’ activities, we conclude that the anticoagulant properties of APC are not mandatory for APC activities in the retina and that VEGF reduction may contribute to the protective effects of APC and 3K3A-APC. Our results highlight the potential use of 3K3A-APC as a novel treatment for CNV and other ocular pathologies.

Highlights

Vascular endothelial growth factor (VEGF) is the main protein that contributes to the stimulation of choroidal neovascularization (CNV) and the breakdown of the outer blood–retina barrier [1,2]
We previously demonstrated that activated protein C (APC) has the ability to inhibit the growth of newly formed CNV, inhibit pathological leakage from CNV, and tighten the outer blood–retina barrier (oBRB)
The protective effects of APC and 3K3A-APC in the retina seem to be promising as potential treatment for CNV and nAMD

Summary

Introduction

Choroidal neovascularization (CNV) is the pathological growth of neovascular blood vessels from the choroid underlying the retinal pigmented epithelium (RPE) towards the sensory retina. Vascular endothelial growth factor (VEGF) is the main protein that contributes to the stimulation of CNV and the breakdown of the outer blood–retina barrier (oBRB) [1,2]. Most patients with CNV are treated with intravitreal administration of drugs targeting VEGF, there remains a large unmet need for additional and alternative therapies to address the limited visual outcomes and the treatment burden with anti-VEGF therapy [3].

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