Effect of VEGF and Anti-VEGF Compounds on Retinal Pigment Epithelium Permeability: An in vitro Study

Abstract

Purpose: : The purpose of this study was to evaluate the effect of two VEGF isoforms (121 and 165) and two anti-VEGF compounds (ranibizumab and pegaptanib sodium) on the permeability of retinal pigment epithelium (RPE) cells in vitro.

Methods: : RPE permeability was assessed on ARPE19 cells grown onto inserts of polytetrafluoroethylene previously treated with ammonia gas plasma. Paracellular permeability to ions was measured by means of transepithelial electrical resistance (TEER). Permeability to non-ionic molecules was gathered by the amount of 4kDa or 70 kDa fluorescein dextran (FD) passing across the monolayer within 2 hours. VEGF isoforms, ranibizumab and pegaptanib sodium were added at the culture media singularly or as a combination (VEGF + anti-VEGF compound) before each permeability assay. Doses were: for recombinant human VEGF121 and VEGF165 10ng/ml, for ranibizumab 0.125mg/ml and pegaptanib sodium 0.08 mg/ml. Control wells contained standard culture media with 1% fetal bovine serum and IgG from human serum 0.1mg/ml, respectively. All the experiments were performed in triplicate with the final value being averaged.

Results: : Only VEGF165 applied at the apical side of the monolayer induced a statistically significant decrease of TEER (p=0.001). No changes in TEER were observed when pegaptanib sodium or ranibizumab were apically administered together with VEGF165.Both VEGF isoforms significantly increased permeability to 4kDa dextran (p<0.01). Apical administration of ranibizumab or pegaptanib sodium per se as well as co-administration with VEGF121 induced a statistically significant increase of permeability to 4 kDa FD (p=0.001, p=0.009, p=0.0003, p=0.006, respectively). Little or no effect on permeability was noted after co-administration of VEGF165 with pegaptanib (p=0.02) or ranibizumab (p=0.07).

Conclusions: : Both VEGF isoforms and anti-VEGF compounds seem to have an effect on human RPE permeability in vitro. The extent and the characteristics of this effect is however complex and requires further investigations.

Keywords: retinal pigment epithelium • vascular endothelial growth factor