Effects of avastin on expression of AQP4 in Müller cells under hypoxia.

The aim of this study was to investigate the effects of Avastin on aquaporin4 (AQP4) expression in human retinal Müller cells in vitro under hypoxia, so as to explore the mechanism of Avastin treating retinal edema. The human Müller cells were cultured using the enzymatic digestion method. Müller cells were identified under the transmission electron microscopy and by using immunofluorescence staining. By using semi-quantitative reverse transcription polymerase chain reaction (RT-PCR), the expression of AQP4 mRNA and VEGF mRNA in Müller cells cultured with 500 μmol/L CoCl(2) for 0, 3, 6, 12 and 24 h, and with 0, 100, 300, 500 and 700 μmol/L CoCl(2) for 24 h was detected. The expression of AQP4 mRNA in Müller cells cultured with 50 ng/mL exogenous vascular endothelial growth factor (VEGF) for 0, 0.5, 1, 2 and 4 h, and with 0, 25, 50 and 75 ng/mL VEGF for 24 h was detected. Amplified cDNA products of AQP4 mRNA in Müller cells cultured with 500 μmol/L CoCl(2) and 200 μg/mL Avastin for 24 h were detected. The results showed that more than 95% cells displayed positive immunofluorescence reaction. Characteristic 8-10 nm intracellular filaments could be seen in the cytoplasm under the transmission electron microscopy. In the CoCl(2) experimental groups, the expression of AQP4 mRNA and VEGF mRNA in Müller cells was increased as compared with the control group. Alteration of AQP4 mRNA and VEGF mRNA levels showed a significantly positive correlation (r (2)=0.822, P<0.05). The expression of AQP4 mRNA in Müller cells was increased by VEGF. The expression of AQP4 mRNA was significantly decreased by Avastin as compared with the control group. It is suggested that Avastin can decrease the expression of AQP4 mRNA in human Müller cells under chemical hypoxic conditions partially via VEGF path, which may be one of the mechanisms of Avastin treating retinal edema.