Objective      To determine the effect of retinal pigment epithelial (RPE) cells with adenovirus-slit2 (Ad-slit2) transfection on the migration and tube formation of choroidal vascular endothelial (RF/6A) cells in a co-culture system.        Methods      After RPE cells were transfected with ad-slit2 or ad-null for 24 and 48 h

the expression of slit2 and vascular endothelial growth factor (VEGF) at mRNA and protein levels was quantified by RT-PCR and Western blotting

and the level of secreted VEGF protein from the media of RPE cells were investigated by ELISA. Coculture models (RPERF/6A) were used to observe the effects of RPE cells transfection with ad-slit2 on the migration and tube formation of RF/6A by Transwell chamber test and Matrigel invasion assay respectively.        Results      After ad-slit2 transfected to RPE cells for 24 and 48 h

the expression of slit2 and VEGF at mRNA and protein levels was obviously increased. At the same time

the level of secreted VEGF protein from the media of RPE cells was also elevated. In the coculture system

the number of RF/6A migrated was 40.6±4.5

36.7±3.5

67.7±4.2

36.0±3.6 and 79.7±3.5 in the blank control group

ad-null for 24 h group

ad-slit2 for 48 h group

ad-null for 48 h and ad-slit2 for 48 h group respectively

the total length of tube formation of RF/6A was 3.95±0.31

4.53±0.26

6.04±0.34

4.09±0.18

7.27±0.45 mm respectively

and the number of tube was 8.7±3.2

8.9±3.6

15.9±4.2

8.3±2.4

and 23.3±4.5 respectively. There were significant differences in the above indexes between the ad-slit2 for 24 h group

ad-slit 2 for 48 h group with blank control group respectively (P0.05).        Conclusion      RPE cells with ad-slit2 transfection promote the migration and tube formation of RF/6A in vitro. Slit2 gene in the RPE cells may take part in the formation process of choroidal neovascularization.