Comparison of effects of oxygen and antioxidative enzymes on cell growth between retinal pigment epithelial cells and vascular endothelial cells in vitro.

We assayed the proliferation of porcine retinal pigment epithelial (RPE) cells, bovine melanotic and amelanotic RPE cells, and bovine aortic endothelial cells exposed to 20, 10 and 5% oxygen and compared their responses to oxygen and antioxidative enzymes (superoxide dismutase and catalase). Irrespective of the cell type, the cell growth was optimal in 10% oxygen that is most closely approximating to the oxygen concentration prevailing in the cellular environment of the choroid and the retina in vivo. However, the effects of oxygen concentrations were cell specific because bovine endothelial cells were influenced by lowering of oxygen concentrations more significantly than bovine and porcine RPE cells. Moreover, addition of antioxidative enzymes caused significant improvement in growth of porcine RPE cells, but had no significant effects on bovine RPE cells. On the contrary, the bovine vascular endothelial cells represented the only one cell type significantly inhibited by antioxidative enzymes, i.e., a decrease in reactive intermediates of oxygen was seen in the media. Our results show that responses of vascular endothelial cells to reactive species of oxygen were distinctly different from those of RPE cells and more easily influenced by the environment related to hypoxia than RPE cells.