Inhibition of human retinal pigment epithelial cell attachment, spreading, and migration by the human lectin galectin-1

PURPOSE Adhesion and migration of dislocated retinal pigment epithelial (RPE) cells are initial steps in the pathogenesis of proliferative vitreoretinopathy (PVR). The role of the endogenous lectin, galectin-1, in attachment, spreading, and migration of human RPE cells was investigated from a therapeutic perspective. METHODS Human RPE cells were treated with galectin-1 concentrations that ranged 0-250 microg/ml. Cell viability was tested by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazoliumbromide (MTT) assay. Galectin-1 binding to the RPE cells was investigated by immunocytochemistry. Attachment of RPE cells was assessed on 96-well plates coated with laminin, or fibronectin, or galectin-1, or the glycoprotein-lectin combinations and subsequent MTT-testing. RPE migration in the absence or presence of galectin-1 on the respective substrates was tested using a modified Boyden chamber assay with platelet derived growth factor (PDGF)-BB as the chemoattractant. Cellular spreading was characterized by cytoplasmic halo formation of RPE cells after three hours in contact with the surface coating. RESULTS Galectin-1 bound to the cell surface. Binding could be inhibited by a beta-galactoside. MTT assays revealed no toxicity within control limits for the concentration range tested. When added to the medium, galectin-1 dose-dependently inhibited RPE cell attachment, spreading, and migration by more than 70%, irrespective of the substratum tested. When coated onto the plastic surface, galectin-1 alone impaired spreading and migration of RPE cells, and reduced attachment to and migration on fibronectin by up to 80%. CONCLUSIONS Galectin-1 inhibits RPE cell attachment, migration, and spreading in vitro with no apparent cytotoxicity. This activity of the endogenous effector deserves consideration as a potential therapeutic agent for the prevention of PVR.