The association of blue light-induced human retinal pigment epithelium cell damage with intercellular free Ca2+ change in vitro

Abstract

Background Investigating the association of blue light-induced damage of retinal pigmenepithelial (RPE) cellwith intracellulaCa2+ conteniimportanfounderstanding the mechanism of retinal disorders.Objective Thistudy wato establish blue light-induced damage model of human RPE celland explore the relationship between the damage of RPE cell and intracellulaCa2+ content.MethodHuman RPE cellwere cultured and passaged.Cell vitality waassayed by trypan blue staining.Fourth-generation cellwere used in these experiments.The cellwere exposed to blue lighwith an intensity of (2000±500)lx fo3,6,9 o12 hours,and the rate of apoptosiwaassayed by TUNEL to assesthe optimal irradiation time focellcultured.The cellwere then randomized into the withouirradiation group,irradiation only group,nifedipine group,ligh+ nifedipine group,(-) BayK8644 group and ligh+ (-) BayK8644 group.The laseconfocal microscope waused to determine the fluorescence intensity of intracellulafree Ca2+ aan excitation wavelength of 488 nm and an emission wavelength of 505 nm.The cell imagewere analyzed using computesoftware.The differenceof fluorescence intensity among the differengroupwere compared by one-way analysiof variance.ResultTrypan blue staining showed thathe viability of RPE cellwamore than 90％ afteculturing and passaging.No apoptoticell waseen aftelighexposure fo3 hours.However,differennumberof apoptoticellappeared aftelighexposure fo6,9 and 12 hours.The fluorescence intensity of intracellulafree Ca2+ in the nifedipine group wasignificantly lowethan thaof the withouirradiation group othe ligh+ nifedipine group(both aP=0.000).Lasescanning confocal microscopy showed thathe fluorescence intensitieof intracellulafree Ca2+ in the irradiation only group,(-) BayK8644 group,ligh+ (-)BayK8644 group were highethan thaof the withouirradiation group,with statistical significancebetween them(all P=0.000).No significandifferencewere found in the fluorescence intensity of intracellulafree Ca2+ between the ligh+ nifedipine group and withouirradiation group awell abetween the (-)BayK8644 group and the ligh+(-) BayK8644 group(P =0.339,P =0.410).ConclusionThe optical conditionfoblue light-induced RPE cell damage were exposure of blue-ligha(2000± 500) lx fo6 hourand culturing the cellfo24 hours.Blue lighexposure can induce damage of human RPE cellprobably by triggering the increase of intracellulafree Ca2+ concentration. Key words: Light/damage; Retinal pigmented epithelium; Calcium ion/intercellular, free, antagonist,agonist ; Apoptosis