Study On The Experimental Choroidal Neovascularization

Objective: l.This study was designed to establish an experimental CNV model in BN rats,which could exhibit high reproducibility. and to determine if Ang-2 , Tie-2, VEGF-B and Flt-1 might play a role in the development of BN rats CNV. and if endostatin might inbibit the development of BN rats CNV.Method: 1.10 BN rats were received krypton red laser. The development of CNV was examined by FFA and the histology after photocoagulation. 2. 15 BN rats were photocoagulated by krypton laser in double eyes as the experiment group,the other 15 BN rats were dilated the pupil but not photocoagulated as the control. The retina was processed for immunohistochemistry of Ang-2, Tie-2, VEGF-B and Flt-1 and in situ hybridization of Ang-2mRNA and VEGF-BmRNA on days 7, 14, 28,56 and 84 days after photocoagulation. 3.The double eyes of 12 were received krypton laser to induce CNV. In the treatment group, endostatin 100μl(0. 5mg/ml) was administered to 12 rats retrobulbarly immediately after laser for 3 times every 2 days. The control rats were received BSS 100μl in the same method. CNV was evaluated on days 7 and 14 after photocoagulation by FFA.The rats were killed on the 14^thday after photocoagulation.The CNV area was measured .The expression of FVIIIR:Ag was detected . The results were semi-quantified and analyzed.4.The experimental data were expressed as the mean±S.D. and statistical significance was determined by ANOVA or t-test.Results: 1. Disciform fluorescein leakage was observed and confirmed the formation of CNV.CNV could be sustaining to 84 days. 2. Ang-2 mRNA was not detected in normal retina. Ang-2 mRNA expressed in the ganglion cells, the inner nuclear layers and the lesion of CNV after photocoagulation.Ang-2 mRNA positive staining density is the highest at the 7th day after photocoagulation(P<0.05).There was no significant changes from days 14 to 84 (P>0.05 ) .The positive staining location and variational trend of Ang-2 and Tie-2 were the same as that of Ang-2 mRNA in laser eyes.Ang-2 was not detected but Tie-2 expressed in the choroidal vascular endothelial cells in normal eye.VEGF-BmRNA expressed in the ganglion cells, the inner nuclear layers ,the RPE and the retinal and choroidal vascular endothelial cells in normal eyes. In laser retina ,it was found in the ganglion cells, inner nuclear layers , RPE , retinal and choroidal vascular endothelial cells and the lesion of CNV.Its positive staining was the strongest at the 14th day(P<0.01) and didn't changed evidently in 28 to 84 days ( P>0.05 ) .VEGF-B expressed in the same way as that of VEGF-BmRNA.Flt-1 expressed in the RPE,outer limiting membrane and outer plexiform layer in normal eye.And there was light staining in outer nuclear layer and the inner part of photoreceptor.7 days after photocoagulation Flt-1 was detected in the ganglion cells,inner nuclear layer,lesion of outer nuclear layer and CNV region.The variable trend is similar to that of VEGF-B. 3. FFA demonstrated that the incidence of CNV in treatment group is lower than control group (P<0.05 ) .Histological examination showed the CNV area is also smaller in treatment group than in control group (P<0.05 ) . FVIIIR:Ag positive staining was detected in vascular endothelial cells of retinal big vessel,small vessel of neural fiber layer and choroidal vascular tube in the normal and non-photocoagulation eyes. 14 days after photocoagulation, FVIIIR:Ag was still found in these places. At the CNV region FVIIIR:Ag red staining of was very strong.The density of treatment is lower than that of control group (P<0.05 ) . Conclusion :1.Krypton laser photocoagulation can be successfully used to produce CNV experimental model in the BN rat. CNV pathologic structure possesses stability and lasts long. The model exhibit high...