Previous in vitro studies have shown the antiproliferative effect of 5-FU on rabbit conjunctival epithelial cells,
28 29 30 31 human scleral fibroblasts,
32 and human Tenon’s capsule fibroblasts.
33 Antiproliferative effects have also been shown on rabbit corneal epithelial cells,
29 32 34 bovine corneal endothelial cells,
35 rabbit lens epithelial cells,
36 and human retinal pigment epithelial cells.
37 However, these studies have never been conducted in the same experimental conditions. Therefore, the comparison of in vitro studies
(Table 2)is difficult because of the difference in cell culture conditions, growth times, and evaluation methods used. In most of the published in vitro studies, the cells were grown to confluence in serum-containing medium in the presence of 5-FU, after which cell numbers were evaluated by a hemocytometer or a Coulter counter. Growth times varied in most of the studies from 2 to 3 days to 5 to 6 days. The estimated EC
50 is in the same concentration range—approximately 5 × 10
−4 mg/mL. The EC
50 in the present study was higher (∼5 × 10
−2 mg/mL) most likely due to shorter exposure times. In a recent study of a human conjunctival cell line (Wong-Kilbourne derivate of Chang conjunctiva), 5-FU induced an apoptonecrotic cell death with an IC
50 of 7 × 10
−3 mg/mL after 72 hours of exposure.
38 In the same study with the MTT cytotoxicity test, 5-FU was shown to induce significant inhibition in proliferating rabbit Tenon’s fibroblasts at the concentrations of 1 × 10
−2 mg/mL or greater after 24-hour exposure.
38