Radiation response of porcine RPE cells in vitro

Purpose. To investigate the antiproliferative effect of ionizing radiation on retinal pigment epithelial (RPE) cells that are supposed to play a major role in the pathogenesis of proliferative vitreoretinopathy (PVR). Methods. RPE cells from pig eyes were irradiated with doses ranging from 4 to 16 Gy (1 Gray = 1 Joule/kilogram). Cells were counted at 1, 2, 3, and 4 weeks (Experiment 1) or 1, 2, 4, and 6 weeks (Experiment 2) after treatment. In Experiment 3, cells were trypsinized 24 h after radiation and seeded again. Colonies were counted 10 days later, and the surviving fraction was determined. Results. The numbers of cells and colonies were inversely correlated to the doses applied. In Experiment 2, cell numbers of radiated cultures remained stable during the time of follow-up, whereas, in Experiment 1, significant proliferation occurred in treated cultures as well as in controls. This may be due to the higher growing rate that was found in the cultures of Experiment 2, compared to those of Experiment 1, at the time of radiation. In Experiment 3, a D-0 value of 0.72 Gy was found. Conclusions Proliferation of RPE cells can be suppressed by irradiation in a dose-dependent manner. Therefore, radiotherapy may be useful in the treatment of PVR. Its effect probably depends on the stage or activity of PVR at the time of radiation.