Purpose: To study the toxicity of triamcinolone acetonide (Kenalog; Bristol-Meyers Squibb, Princeton, NJ) on retinal pigment epithelial (ARPE-19) and retinal neurosensory (R28) cells.
Methods: ARPE-19 and R28 were grown in tissue culture in Dulbecco's modified Eagle's medium (DMEM) containing 10% fetal bovine serum. Cells were treated with 50, 100, and 200 microg/mL concentration of triamcinolone acetonide for 2, 6, and 24 hours. The cells were also treated with the steroid without the vehicle and with the vehicle alone, in which triamcinolone acetonide was suspended. Toxicity was determined by trypan blue dye-exclusion and WST-1 mitochondrial dehydrogenase assays.
Results: Vehicle alone did not reduce the viability of ARPE-19 or R28 cells and also did not affect the mitochondrial dehydrogenase activity of the cells. The mean cell viability of ARPE-19 and R28 cells after exposure to triamcinolone acetonide with vehicle 200 microg/mL for 24 hours was 70.7% +/- 10.61% and 75.35% +/- 12.42%, respectively compared with the untreated ARPE-19 (92.7% +/- 6.24%, P < 0.01) and R28 cells (90.63% +/- 5.62%, P < 0.001). The mean cell viability of ARPE-19 cells after exposure to triamcinolone acetonide (200 microg/mL) alone without the vehicle was 84.96% +/- 0.32%, 85.2% +/- 3.26%, and 84.73% +/- 2.71% at 2, 6, and 24 hours, respectively, compared with the untreated ARPE-19 cells (P < 0.001). The R28 cells exposed to triamcinolone acetonide (200 microg/mL) without the vehicle also had a significant reduction in the mean cell viability at 24 hours (86.42% +/- 3.87%, P < 0.001) and 6 hours (89.03% +/- 1.01%, P < 0.01). There was a significant reduction in the mitochondrial dehydrogenase activity in the ARPE-19 cells when treated with both triamcinolone acetonide, with or without the vehicle at a concentration of 200 microg/mL at all time points (P < 0.01). R28 cells did not have any significant reduction in mitochondrial dehydrogenase activity when treated with triamcinolone acetonide without the vehicle at any of the doses, but there was a significant reduction when the R28 cells were treated with triamcinolone acetonide with vehicle (200 microg/mL) for 24 hours (P < 0.05). Triamcinolone acetonide with vehicle caused a greater reduction in cell viability and mitochondrial dehydrogenase activity than did triamcinolone without vehicle, in both cell lines, although the difference was not statistically significant.
Conclusions: Triamcinolone acetonide is toxic to proliferating cells of retinal origin in vitro at doses normally used in clinical practice. The vehicle by itself appears to be nontoxic to the cells, but may have a potentiating effect on the cytotoxicity of triamcinolone acetonide. The results of this in vitro study cannot be directly extrapolated to clinical practice, but, based on these data, further studies may be warranted.