Purpose:
Angiogenesis or neovascularization can be defined as to the development of new vessels. Pathological retinal and choroidal neovascularization causes bleeding, edema and fibrosis being responsable of visual impairment and blindness. There are various diseases in which neovascularization plays a key role, being the most common ones diabetic retinopathy, retinal vein occlusion, retinopathy of prematurity and age related macular degeneration. Vascular endothelial growth factor (VEGF) has been associated to ocular neovascularization in these pathologies. VEGF promotes blood vessel formation by binding and activating VEGF receptors and increases vascular permeability. It also contributes to endothelial-cell survival and proliferation in blood and lymphatic vessels. Retinal pigment epithelium cells and Muller cells are the major sources of VEGF and endothelial cells the primary targets of VEGF in the retina. Our aim was to evaluate retinal vascular endothelial growth factor (VEGF) expression by means of a molecule that is composed by an antibody against VEGF labeled with fluorescein isothiocyanate (URMI, Uruguayan Retinal Molecular Imaging) in a rabbit eye isquemia model induced by laser.
Methods:
Ten rabbits had their right nasal retinal vein oclussion with Argon laser, 72 hours later an angiography was performed by intravenous inyection of URMI. Five of those 10 rabbits received intravenous Avastin® 10 mg/kg one hour prior URMI injection. All rabbits had URMI angiographies performed with fluorescent filter.
Results:
URMI angiography showed the pattern of a normal dynamic angiography being able to characterize all of the angiogram phases. Twenty four hours postinjection persisted a clear fluorescent area surrounding the lesion previously performed with laser. In those rabbits that were previously treated with Avastin® the URMI angiography was similar to the ones performed to the other rabbits, but we were unable to detect fluorescent surrounding the lesions twenty four hours postinjection. The parameters of the angiographies were maintained in order to reproduce the technique.
Conclusions:
URMI angiography has a similar angiographic pattern as the one performed with sodium fluorescein but has a specific binding to VEGF that allows recognition of VEGF production areas. This fact would enable angiographic diagnosis of different ophthalmic disorders and could be used to guide their pharmacologically treatment or act as a target for laser beam therapy.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: non-clinical • vascular endothelial growth factor