Purpose
To assess if two different breeds of rabbits, New Zealand white (NZW) albino versus pigmented Dutch belt, demonstrate differences in the degree of inducible experimental choroidal neovascularization (CNV) since differential experimental retinal neovascularization was seen between NZW rabbits and pigmented rabbits.
Methods
Young adult NZW white rabbits (12) and Dutch belt pigmented female rabbits (12) weighing between 2 and 3 kg were utilized. All animals were kept on a normal 12 hr light/dark cycle and fed ad libitum. Color fundus and fluorescein angiography (FA) were performed prior to implantation of the VEGF/bFGF pellet and at wks 1,2,3, and 4. Photography was performed with a Topcon 50EX retinal digital camera system. The 1.5 mm VEGF/bFGF implant was placed between the 9 and 10 o'clock position in the suprachoroidal space, which was created by passing a cyclodialysis spatula between the choroid and sclera. Analysis of the angiographic leakage was based on severity of leakage over time. Enucleation was accomplished at week 4 with general histologic evaluation being performed.
Results
Both time course and robustness of CNV were similar in these two animal species. Average leakage for NZW rabbits and Dutch belts were 2.5 and 2.75, respectively. No significant differences were noted between NZW rabbits and Dutch belt female animals with sustained release VEGF/bFGF implants (p< 0.001). Negative controls consisting of blank implants for both types of animals were 0 by week 4. General morphologic analysis also was similar for both types of animals.
Conclusions
This study indicates that two different breeds of rabbits (New Zealand albino vs Dutch belt) display similar experimental choroidal NV responses to the same amounts of both VEGF and bFGF unlike experimental retinal NV. Lack of pigmentation in the albino rabbit allows for observation of the choroidal vasculature and its patterns during the time course of experimental CNV. Since genetic heterogeneity most likely exists for angiogenic responses, defining the genetic role in the regulation of ocular angiogenesis will lead to the design of more effective drugs. However, suitability of this animal model for AMD drug development does not seem to be compromised by choice of genetically different animals.
Keywords: 453 choroid: neovascularization •
609 neovascularization •
700 retinal neovascularization