RADIATION RESPONSE OF PORCINE RPE CELLS IN-VITRO

Purpose. To investigate the antiproliferative effect of ionizing radia tion on retinal pigment epithelial (RPE) cells that are supposed to pl ay a major role in the pathogenesis of proliferative vitreoretinopathy (PVR). Methods. RPE cells from pig eyes were irradiated with doses ra nging 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 (Experi ment 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 ce lls and colonies were inversely correlated to the doses applied. In Ex periment 2, cell numbers of radiated cultures remained stable during t he time of follow-up, whereas, in Experiment 1, significant proliferat ion occurred in treated cultures as well as in controls. This may be d ue to the higher growing rate that was found in the cultures of Experi ment 2, compared to those of Experiment 1, at the time of radiation. I n Experiment 3, a D-0 value of 0.72 Gy was found. Conclusions Prolifer ation of RPE cells can be suppressed by irradiation in a dose-dependen t manner. Therefore, radiotherapy may be useful in the treatment of PV R. Its effect probably depends on the stage or activity of PVR at the time of radiation.