PEDF Modulation of Schlemm's Canal Barrier Function

Abstract

Purpose: The role of pigment epithelium-derived factor (PEDF) in glaucoma is unknown. There is a higher risk of glaucoma among people of African descent, also the reason for which is unknown. The goal of this study was to measure and compare levels of PEDF in human aqueous humor from Caucasians and African Americans and examine PEDF effects on the permeability of Schlemm’s Canal (SC) endothelia, part of the blood-aqueous barrier. Methods: Eight African American and 10 Caucasian aqueous humor samples were assayed for PEDF using ELISA. SC cells plated at confluence on Transwell filters were exposed to human retinal pigment epithelia media or purified PEDF and assayed for transendothelial electrical resistance (TEER) using an ohmmeter at 0, 24, and 48 hour time points. Results: PEDF levels in aqueous humor were detected in 14/18 samples, ranging from non detectible levels to 374.11ng/ml. PEDF maintained net TEER of human SC endothelial monolayers from 11 ± 2 to 10.16 ± 3.31Ωcm² in hRPE media (3.38ng/mL) and 13.7 ± 0.6 to 15.7±0.6Ωcm2 in purified PEDF (1μg/mL). Conclusions: There is no statistically significant relationship between PEDF content and race of donor for aqueous humor. PEDF increases and stabilizes resistance in SC and has an effect on the blood-aqueous barrier.