A SEMA3E MUTANT RESISTANT TO CLEAVAGE BY FURINS (UNCL-SEMA3E) INHIBITS LASER INDUCED CHOROIDAL NEOVASCULARIZATION

Abstract

 

Purpose

 

Abnormal subretinal choroidal neovascularization (CNV) is a major blinding consequence of the exudative form of age-related macular degeneration (AMD). Anti-angiogenic agents may be useful in preventing CNV formation. A point mutated form of semaphorin-3E resistant to cleavage by furin like pro-protein convertases (UNCL-Sema3E) is known to display potent anti-angiogenic properties. UNCL-Sema3E is unique by its action of counteracting activities of angiogenic growth factors other than VEGF, such as affecting receptors of neuropilin and plexin. The purpose of this study is to determine if UNCL-Sema3E may be used in-vivo to inhibit CNV formation.

 

Methods

 

Cultured vascular endothelial cells were stimulated with VEGF (10 ng/ml) in the presence or absence of UNCL-Sema3E/Fc (1.5 μg/ml). After 10 min. at room temperature the cells were lysed and ERK1/2 phosphorylation determined. CNV was induced in the eyes of Evans-Long rats by laser photocoagulation (n=128) followed by an intravitreal injection of either UNCL-Sema3E (125 μg/5 μl), avastin (125 μg5 μl), or vehicle (5 μl) as control. After a week flat whole mounts of retinas where used to determine CNV frequency and size. Results were assessed by the staining of blood vessels with isolectin and calculating the area of stained blood vessels using the Image-J morphometric software.

 

Results

 

UNCL-Sema3E inhibits efficiently both VEGF and bFGF induced signal transduction in cultured vascular endothelial cells. UNCL-Sema3E injected into the vitreous cavity reduced the area of laser induced CNV (n=65) by 50% (64040 ± 7321 μm² for controls (n=61) vs 32720 ±- 2369 μm², P<0.0001) displaying efficacy similar to that of bevacizumab[SS3] (n=54).

 

Conclusions

 

UNCL-Sema3E inhibits laser induced CNV formation in the rat model as efficiently as bevacizumab. This suggest that UNCL-Sema3E may be considered as a possible therapeutic agent for the treatment of exudative AMD that is resistant to current anti-VEGF treatments because it acts on a different anti-angiogenic pathway.