Effects of vitamin A on retinal pigment epithelial cells in vitro

Human retinal pigment epithelial (RPE) cell monolayers were used in an in vitro wound-healing experiment. Wound closure were studied over time in the presence of various concentrations of all-trans retinol (vitamin A). It was found that 5-20 micrograms/ml (17.5-70 mumol/l) of vitamin A significantly inhibited wound closure by inhibiting cell migration and proliferation. In a collagen gel-contraction model, similar doses of vitamin A partially inhibited cell contractility. Cellular morphology, as assessed by phase-contrast microscopy, changed from a regular polygonal shape to an elongated stellate shape. Indirect immunofluorescence patterns of fibronectin, actin, tubulin, and vimentin were altered after exposure to vitamin A. All these effects were reversible after removal of the drug from the medium. Modulation of RPE growth and cell-mediated contraction may be useful in the treatment of ocular proliferative diseases.