Setting Up Choroidal Neovascularization Animal Models On Tree Shrews By Laser Inducing

Objective: To explore the feasibility and morphological and histological changesof establishing choroidalneovascularizationanimal model on tree shrews through laser inducing.Methods:1. To establish animal models of laser-induced damage.Healthy adult tree shrews were divided into six groups (Group 1-6), and each group had 4 tree shrews (8 eyes). Group 6 was the blank control group and received no treatment. After injecting of sodium pentobarbital anesthesia into tree shrews’abdominal cavity, eyeswere dilated three times using compound tropicamide on. Oxybuprocaine hydrochloride eye drops were applied to anesthetize ocular surface. All the 5 groups received krypton red laser retinal photocoagulation.Eight laser spots were made about 1PD from the laser disc on each eye. When there were blisters on blasting sound and retinal bubble shown, it’s considered that brunch membrane was damaged.2. Judgement of successful modelingLaser photocoagulation surgery bubbles formation was thesign of Bruch’s membrane rupture and the basis for the formation of CNV. The measurement of success is fluorescein leakageappeared in FFA.3. Evaluation of the model(1).FFA: FFA examination separately was performed on 3,7,14,21, and 28 days after laser. Regarding CNV determine, observe CNV leakage by late image of radiography, then computer image analysis system is calculated for each time point CNV fluorescein leakage integrated area.(2) Immunohistochemistry include:VEGF-A, PIGF, Ⅷ factor4. Statistical AnalysisTo Make overall evaluation of laser-induced CNV model on tree shrews by analyzing the success rate of animal, the clinical manifestations and pathological manifestations and similarity of the process of human diseases.Results:1. At the same time but different early, middle and late stage, from the FFAfluorescein leakagearea, the earlier stage is the smallest,p<0.05. There are difference leakage areas between these three stage, whose difference has the statistically significance. FFAatdifferenttime pointsduring the same periodshowed a7to 14 days forleakageareaduring the peak period, with 3 days,7 days,14 days,21 days, an increase of 28 daystime, FFA leakagearea is increased, p<0.005. FFAleakagearea has relation with timepoints, whose difference also has statistically significance.2. Tree shrew is non-humanprimate, whose retinalstructure is very similar to humans and HEstaining can be seen. Normal tree shrews’Choroidal layers in blank contrast group is clear and complete and can be divided into 10 layers, which are nerve fiber layer, ganglion cell layer, inner plexiform layer, outer plexiformlayer, externalplexiformlayer, outer nuclear layer, external limiting membrane, conerodcell layer, bruch film from inside to outside. On the former 5 groups, after laser damage, it can see the retinal layers widely vasodilation and congestionwithin the lumen.3. After the laser photocoagulation, make comparison between experimental group and blank contrast group in PIGF,VEGF-A and Ⅷ factor staining. Using SPSS 17.0 software, the experimental resultswere expressed as mean±standard deviation, Levene F test on color intensity, color area and total scores after lasering, result isP<0.05. According to T test, after PIGF, VEGF-Astaining, prolonged expression of experimental group and blank contrast group were significantlyin-creased with modeling time goes by. (P<0.05) ThroughT test,Ⅷcytokine staining expression in experimentalgroup started to increase at the 14th day, so then there are statistically significant differences betweenthe control groupfrom14 days. (P< 0.05).Therefore, it can be considered that tree shrews’VEGF, PIGF-1, Ⅷfactorwere significantlyincreased afterretina was damaged by laser.Conclusion1.The red laser retinal photocoagulation caninduce the formation of tree shrew schoroidal neovascularization.2.FFA confirmed that modeling success rate of 60%, HE staining showed only extensive retinal ganglion cell layer and inner tube vasodilatation congestion, no mechanical damage be seen, failed to showthe growth ofchoroidal neovascularization, which may be related to inaccuracy of pathological based site.3.After thelaserdamage totree shrews’ retinal, along withobservationtime, thecorrelation factor VEGF retinal neovascularization, PIGF-1, Ⅷ factor were significantly increased.