Human ocular posterior segments free of any known ocular disease were obtained from Chongqing Eye Bank (Chongqing, China). The retina was torn from RPE with forceps, and the RPE was rubbed off of the choroid with a cotton swab. Choroids were torn from sclera, and endothelial cells were isolated from 2 choroids of 1 donor by treatment with 0.2% type II collagenase in minimum essential medium (Gibco, Grand Island, NY, USA) at 37°C and 5% CO2 until the tissue was visibly digested. The cell suspension was filtered through sterile 70-mm and 40-mm filters (BD Biosciences, Franklin Lakes, NJ, USA). The filtered suspension was centrifuged at 300g and resuspended in isolation medium containing anti-CD31 magnetic beads (Miltenyi Biotec, Bergisch Gladbach, Germany) according to product instructions. The isolated cells were resuspended in endothelial growth medium-2 (EGM-2 MV; Lonza, Basel, Switzerland) with 5% fetal bovine serum (FBS) and seeded onto 6-well plates (Corning, Tewksbury, MA, USA) coated with fibronectin (BD Biosciences). Choroidal endothelial cells were incubated at 37°C and 5% CO2 in a humidified atmosphere. Medium was changed every 4 days. Cells were passaged with 0.025% trypsin and 0.01% EDTA in sterile phosphate-buffered saline (PBS). Choroidal endothelial cells between passages 3 and 5 were used for experiments.