Effect of mitomycin-C on human retinal pigment epithelium in culture

Purpose. To determine the effect of mitomycin-C on confluent and non-confluent human retinal pigment epithelium (RPE) in tissue culture. Methods. The effect of mitomycin-C on confluent RPE was determined by treating first passage confluent cells with 0.01, 0.1, 1, 10, 100 or 1000 micromolar (mu M) mitomycin-C for 1, 3. or 7 days. The cell viablility after treatment was determined by using an esterase stain. The effect of mitomycin-C on proliferating RPE was determined by incubating non-confluent cells with the above concentrations of mitomycin-C for 20 min, 1 hour or 24 hours. Results. Mitomycin-C can be toxic to a confluent RPE monolayer, and the LD50 is 421, 28.8 or 0.0632 mu M when cells are continually exposed to mitomycin-C for 1, 3 or 7 days, respectively. Exposure to mitomycin-C at concentrations greater than or equal to 10 mu M for 20-60 min significantly inhibits proliferation of non-confluent RPE. A 24 hour exposure of RPE to 1 mu M mitomycin-C markedly inhibits proliferation of non-confluent RPE with minimal toxicity to confluent RPE. Conclusions. Since exposure of human RPE to mitomycin-C for 24 hours can inhibit cell proliferation at concentrations which are well-tolerated by confluent RPE, mitomycin-C may be a suitable agent for inhibiting RPE proliferation in vivo.