Romanian Journal of Morphology and Embryology 2010, 51(2):327–336 ORIGINAL PAPER VEGF-induced corneal neovascularisation in a rabbit experimental model L. COMAN 1) , OANA ANDREIA COMAN 2) , H. PĂUNESCU 2) , FL. DRĂGHIA 3) , I. FULGA 2) 1) Department of Physiology 2) Department of Pharmacology and Pharmacotherapy 3) Department of Anatomy Faculty of Medicine, “Carol Davila” University of Medicine and Pharmacy, Bucharest Abstract Introduction and Purpose: Various conditions may cause vascularization of the normally avascular cornea. The aim of the present study was to create a reproducible experimental model that could enable the investigation of the phenomena leading to corneal vascularization. This involved creating a software to record the experimental data, enabling a subsequent digital analysis based on the growth models. The VEGF-induced pattern of neovascularization was also investigated. Material and Methods: Twenty-seven rabbits divided in groups were used for the purposes of the present study. Some of them underwent intracorneal implants with or without vascular endothelial growth factor (VEGF) pellets, using an original microsurgical technique. Central and peripheral corneal burns were induced to other groups of animals in order to mimic the neovascularization process induced by inflammation. Finally, Dexamethasone (Maxidex) was given intraocularly, on days 1 and 3 after the onset of neovascularisation, in rabbit groups with both corneal burns and VEGF-implants. Video recording and data analysis of the corneal vascularization were made with an advanced biomicroscope, a computerized imaging system and a special software. A histochemical study of the animals’ eyes was also carried out. Results and Discussion: The recorded data showed the simplicity and reproducibility of the present experimental model. The results showed the importance of VEGF as an initiator and promoter of corneal vascularization through a non-inflammatory mechanism, quite different from the inflammation illustrated by the corneal burn. At the same time, Dexamethasone therapy proved its effectiveness in corneal angiogenesis induced by thermal burn, but not by VEGF-implant. Keywords: corneal vascularization, VEGF, corneal burn, corneal inflammatory process.  Introduction The issue of angiogenesis is relevant not only in physiology, but also in the physiopathology of many illnesses. The genesis of neovessels is crucial in normal growth and development of any tissue. This process is particularly significant in the setting of tumor growth and metastasis, of chronic inflammatory and/or metabolic diseases. During adulthood, this vascularization is im- portant for wound healing and reproduction. The deve- lopment of the angiogenetic phenotype is a complex process, involving the ability of normal or tumoral cells to secrete angiogenetic factors [1]. Angiogenesis is practically a synonym to vascular sprouting. The sprout- ting of new vessel segments follows a well-defined program: degradation of basement membrane, endo- thelial cell proliferation, formation of solid sprouts of endothelial cells connecting a neighboring vessel, and restructuring of the sprout into a lumen lined by endothelial cells and integrated in the vascular network. [2]. This process results in the apparition of intact neovessels, with a permeable channel. It is controlled by a large number of molecules, classified as angiogenic and angiostatic [3]. The angiogenic and angiostatic factors are ennumerated elsewhere (Chang JH et al., 2001) [4]. Angiogenic agents include various growth factors and cytokines, such as b-FGF, VEGF, IL-8, selectine E. Angiostatic molecules, such as thrombo- spodine, angiostatine, and platelet factor 4, hold the same significance [4–7]. The term neovascularization might be used to describe the installation of new vascular structures in previously avascular areas. Within the eye, neovessels are directly responsible for most of the destructive events that are characteristic for certain diseases, such as proliferative retinopathies and age-induced macular degeneration [8–12]. Several laboratories have tried to explain the main role of VEGF as regulator of normal and abnormal angiogenesis [13–16]. Complete and detailed infor- mation on the biologic and clinical implications of VEGF are given in the reviews published by Ferrara N et al. [14, 17, 18]. VEGF (also named VEGF-A) belongs to a gene family that includes placental growth factor (PlGF), VEGF-B, VEGF-C, and VEGF-D. VEGF-A binds to VEGFR1 and VEGFR2, while placental growth factor (PlGF) and VEGF-B binds only to VEGFR1. VEGF-C and VEGF-D bind to VEGFR2 and VEGFR3 [18]. VEGFR1, VEGFR2 and VEGFR3 are receptor tyrosine kinases.