Experimental model for development of proliferative retinopathy after injection of intravitreal VEGF-A 165 in rabbits

Abstract

 

Purpose

 

To develop a proliferative retinopathy experimental model by intravitreal injection of VEGF in pigmented rabbits.

 

Methods

 

A prospective, controlled, comparative, interventional study. Six pigmented rabbits were submitted to intravitreal injection of VEGF-165 in their right eye. Left eye was used as control. In group 1, four rabbits received a 10μg injection and, in group 2, two received 20μg. At baseline and week 1, 2 and 5 all were analyzed with anterior biomicroscopy, retinography, fluoresceinic angiography and OCT images. In the fifth week after the injection the rabbits were euthanized and the eyes were enucleated and submitted to a histological evaluation. The ocular examination was analyzed according to the anatomy of the vessels and evaluated for: disc hyperemia, vascular dilatation and tortuosity, vitreal or retinal leakage, formation of neovascular membrane, vascular narrowing, disc pallor, abnormal vascular pattern, retinal distortion and elevation or capillary non-perfusion.

 

Results

 

Seven days after the intravitreal VEGF-165 injection, all rabbits developed intense neovascularization of the retina and anterior segment. The neovascularization of the posterior pole was similar in both groups, and the anterior segment was more important in group 2. During week 1 and 2, the neovascularization was maintained with minor decrease of conjunctival hyperemia in both groups. At week 5 there was a partial regression of the neovascularization of posterior pole, more prominent in group 1 than group 2, with persistent anterior neovascularization in both groups. After a five-week period, ocular histopathological evaluation showed intense neovascularization in group 2.

 

Conclusions

 

The pilot study for model of neovascularization through intravitreal VEGF-165 injection in pigmented rabbits show that both doses of 10 and 20µg were successful to develop retina and anterior segment vascular growth, and therefore can be used for evaluation of drugs efficacy in future studies.

 

 

Figure 1 A) Colored fundus Retinography and C) Fluorescein Angiography showing intense neovascularization seven days after the VEGF-165 intravitreous injection B) Colored fundus Retinography and C) Fluorescein Angiography showing normal findings

 

 

Figure 2 A)Spectral-Domain OCT showing normal retinal and choroidal layers B)Spectral-Domain OCT showing vitreous opacities and disorganization of the retinal layers.

 

Keywords: 748 vascular endothelial growth factor • 700 retinal neovascularization