Study On Experimental Choroidal Neovascularization And CNV Inhibition With Intravitreal Bevacizumab (Avastin) Injection

Objective1. This study was designed to establish an experimental CNV model in BN rats by laser infusion in order to establish the foundation for studying the mechanism of CNV during 4 weeks.2. The total mRNA of VEGF was detected by RT-PCR. Exam FⅧ-Rag protein expression in CNV and investigate the relationship between VEGF and CNV development.3. Study the evolution of CNV during 3 weeks with intravitreal injection of Bevacizumab(Avastin)1μl(25μg/1μl), so make a preliminary investigation of the treatment effect of Bevacizumab(Avastin)on experimental CNV.Methods1. Five groups of 40 BN rats was photocoagulated by krypton laser in one eye to induce CNV, the laser spots were placed separately using a setting of 50 um diameter, 0.05 second duration ,and 360 mW intensity, surrounding the optic nerve at the posterior pole.2. Fluorescein angiography was performed from 3 day to 4 weeks after laser photocoagulation .The CNV area was measured by early phase FFA. Then the rats were sacrificed immediately, the eyes were enucleated and processed for histopathologic examination and RT-PCR. Exam the FⅧ-Rag protein expression in CNV .Observe the expression of VEGF protein in rat retinal and the lesion of CNV.3. Tow groups of 48 BN rats was photocoagulated by krypton laser in one eye to induce CNV model in one eye, in which 1 group received intravitreal injection of Bevacizumab(Avastin)1μl(25μg/1μl)after photocoagulation one week and the other group received the same volume intravitreal injection of BSS as control. FFA examinations occurred on 1,2,3 week and the eyes were enucleated and processed for histopathologic examination. The area of CNV were measured in early phase FFA. FⅧ-Rag were investigated with immunohistochemistry and were semiquantitatively analyzed.4. The experimental data were expressed as the mean±S.D. and statistical significance was determingd by t-test.Results1. Disciform fluorescein leakage was observed and confirmed the formation of CNV.The immunostaining of FⅧ-Rag and FFA show the persistent increase of the CNV development during 4 weeks.2. During the CNV development,the expression of FⅧ-Rag and VEGF increase gradually. V EGF expression was mainly observed in the Vascular endothelial cells , the ganglion cells , the inner nuclear layers , the retinal pigment epithelial cells in normal retina and the vascular endothelial cells of normal choroids of BN rat . VEGF expressed in the ganglion cells , the inner nuclear layers , lesion of outer nuclear layers inretina after photocoagulation .3. The area and the leakage of CNV in Bevacizumab(Avastin)treated BN rat eyes obviously reduced compared with the control group at each interval. In the treatment group,the expression of FⅧ-Rag depressed. The examination of FⅧ-Rag and FFA verified the depression of CNV compared with the control group at each interval.The density of treatment is lower than that of control group(P<0.05)Conclusion1. krypton laser photocoagulation can be successfully used to produce CNV experimental model in the BN rat. CNV pathologic structure possesses stability.2. VEGF play the important role in CNV development.3. Intravitreal Bevacizumab(Avastin)Injection can inhibit the development of CNV...