|
|
||||||||
1From the Department of Ophthalmology, School of Medicine, University of California, Irvine, California; the 2Department of Ophthalmology, The Ross Eye Institute, and the 3Department of Physiology and Biophysics, The State University of New York, Buffalo, New York.
| Abstract |
|---|
|
|
|---|
METHODS. ARPE-19 and R28 were grown in tissue culture in Dulbeccos modified Eagles medium (DMEM) containing 10% fetal bovine serum. Cells were treated with 50, 100, and 200 µg/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 µg/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 µg/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 µg/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 µg/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 µg/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.
The common adverse effects of ocular steroid therapy are glaucoma and cataract.3 12 13 In addition, given that the commonly used formulation of triamcinolone acetonide (Kenalog; Bristol-Meyers Squibb)), is not formulated for the eye, there is a known risk of pseudoendophthalmitis and a hypothetical potential for clinical retinal toxicity from the vehicle when it is injected intravitreally.14 15 16 There have been reports of toxicity of triamcinolone acetonide on retinal pigment epithelial cells in vitro17 18 whereas ex vivo19 and in vivo20 21 studies have failed to show any significant toxicity in the retina. Triamcinolone acetonide also causes phototoxicity of erythrocytes in vitro and may also have weak photosensitizing properties in vivo.22 We performed this study on retinal pigment epithelial (ARPE-19) and neurosensory retinal (R28) cell lines using two different assays to measure the cytotoxicity of triamcinolone acetonide. The toxicity of triamcinolone acetonide suspension with its vehicle, vehicle alone, and the drug alone without the vehicle were studied separately.
| Materials and Methods |
|---|
|
|
|---|
The cells were plated onto 96-well ELISA plates or 35-mm tissue culture dishes and incubated at 37°C in 5% CO2 to reach 70% to 80% confluence before being exposed to the drug.
Exposure to Triamcinolone Acetonide
Cells were treated with 50, 100, and 200 µg/mL concentration of triamcinolone acetonide (Kenalog; Bristol Meyers Squibb) for 2, 6, and 24 hours. ARPE-19 and R28 cells were also treated with the steroid alone, resuspended in the culture medium at the same concentrations, after removal by centrifugation of the vehicle used for the suspension of triamcinolone acetonide. Triamcinolone acetonide was centrifuged at 5000 rpm for 45 seconds, and the supernatant containing the vehicle was pipetted out. The pellet of triamcinolone was resuspended in an equivalent amount of culture medium to achieve the same concentrations of triamcinolone (50, 100, and 200 µg/mL). The cells were also exposed to the highest concentration of the vehicle that was removed after centrifugation of 200 µg/mL triamcinolone.
Cell Viability Assay
Cell viability assay was performed as previously described.26 Briefly, cells were harvested from the 35-mm dishes by treatment with 0.2% trypsin-EDTA and incubating them at 37°C for 5 minutes. The cells were centrifuged at 1000 rpm for 1 minute and then resuspended in 1 mL of culture medium. Automated cell viability analysis was performed (ViCell analyzer; Beckman Coulter Inc., Fullerton, CA). The analyzer performs an automated trypan blue dye-exclusion assay and gives the percentage viability of cells.
Mitochondrial Dehydrogenase Assay
To assess mitochondrial function, mitochondrial dehydrogenase (succinate-tetrazolium-reductase) activity was determined with the WST-1 (4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate) colorimetric assay (Roche Diagnostics, Indianapolis, IN), as previously described.26 WST-1 is a tetrazolium dye containing an electron coupling reagent that is cleaved by the mitochondrial dehydrogenase enzyme to a formazan dye, and this reaction directly correlates with the number of metabolically active cells. Ten microliters of the formazan dye was added to each well containing cells and medium and incubated for 2 hours at 37°C. Absorbance was measured at 490 nm on a multiwell spectrophotometer (Perkin Elmer, Wellesley, MA). Control wells with culture medium and different concentrations of triamcinolone acetonide but without any cells were also studied, since triamcinolone acetonide is opaque, and as a result influences the spectrophotometer reading. The colorimetric values from these wells were subtracted from the values obtained from the wells containing the cells treated with corresponding concentrations of triamcinolone acetonide to derive the actual colorimetric value. The data presented are from three separate experiments.
Statistical Analysis
Data were subjected to statistical analysis by ANOVA (Prism, ver. 3.0; GraphPad Software Inc., San Diego, CA). Newman-Keuls multiple-comparison test was done to compare the data within each experiment. P < 0.05 was considered statistically significant. Error bars in the graphs represent SEM with experiments performed in triplicate.
| Results |
|---|
|
|
|---|
|
|
|
|
|
|
Mitochondrial Dehydrogenase Assay
ARPE-19 Cells.
The mean mitochondrial dehydrogenase activity of ARPE-19 cells treated with 200 µg/mL triamcinolone acetonide with vehicle for 24 hours was significantly less than the activity of the untreated cells (absorbance at 490 nm 0.112 ± 0.074 vs. 0.541 ± 0.016, respectively; P < 0.01). There was also a significant reduction in the mitochondrial dehydrogenase activity of ARPE-19 cells when treated with 200 µg/mL triamcinolone acetonide with vehicle for 2 and 6 hours (P < 0.01, Fig. 3A ). The reduction in the enzyme activity of the cells when treated with 50 and 100 µg/mL triamcinolone acetonide with vehicle at any of the time points was not significant. The mitochondrial dehydrogenase activity of cells treated with vehicle alone was 0.488 ± 0.092, which was not significantly different from the untreated ARPE-19 cells (0.541 ± 0.016).
|
R28 Cells.
R28 cells treated with 200 µg/mL triamcinolone acetonide with vehicle for 24 hours had a mean mitochondrial dehydrogenase activity of 0.018 ± 0.039, which was significantly less than the mean activity in the untreated R28 cells (0.271 ± 0.016; P < 0.05). Cells treated with 100 and 50 µg/mL triamcinolone acetonide with vehicle for 24 hours had a mean mitochondrial dehydrogenase activity of 0.079 ± 0.061 and 0.080 ± 0.114, respectively, which was not significantly less than the activity in the untreated R28 cells (Fig. 4A) . Cells treated with triamcinolone acetonide for 2 and 6 hours also did not have any significant reduction in mitochondrial dehydrogenase activity. R28 cells treated with vehicle alone did not have any significant reduction in mitochondrial dehydrogenase activity (0.239 ± 0.034) compared with the untreated cells (P > 0.05). Cells treated with triamcinolone acetonide without the vehicle did not have any significant reduction in their mean mitochondrial dehydrogenase activity at any of the three concentrations and time points (Fig. 4B) .
|
| Discussion |
|---|
|
|
|---|
Triamcinolone acetonide has been shown to be toxic to retinal pigment epithelial cells in vitro,17 18 whereas ex vivo19 and in vivo20 21 studies have failed to show any significant toxicity to the retina. Yeung et al.17 reported that triamcinolone acetonide with the vehicle was toxic to ARPE-19 cells and human glial cells (SVG cells) by the mitochondrial dehydrogenase (MTT) assay, but the effect of triamcinolone acetonide without the vehicle was not studied. They studied three concentrations of 10, 100, and 1000 µg/mL over days 1, 3, and 5, and found that there was significant reduction in the mitochondrial dehydrogenase activity of SVG cells at 24 hours at 100 and 1000 µg/mL. They did not find a significant reduction in the absorbance of ARPE-19 cells at 24 hours with any of the concentrations. In contrast, we found in our study that ARPE-19 cells had a significant reduction in the mitochondrial dehydrogenase activity when exposed to 200 µg/mL triamcinolone acetonide with the vehicle for even 2 hours. In addition, we found that 200 µg/mL triamcinolone acetonide without the vehicle also caused a significant reduction in the enzyme activity at 24 hours. We also performed the cell viability assay in our study, and triamcinolone acetonide without the vehicle was toxic to ARPE-19 cells at concentrations of 100 and 200 µg/mL at all three time points, including the earliest time point of 2 hours. Similarly, we found that 200 µg/mL triamcinolone acetonide, with or without the vehicle, was toxic to R28 cells according to the dye-exclusion assay.
Citing concerns about the toxicity of the preservative used in triamcinolone (Kenalog; Bristol-Meyers Squibb),15 27 28 Bakri and Beer29 in a small retrospective, noncomparative series showed that preservative free triamcinolone acetonide was nontoxic to the retina. They used a formulation that did not contain benzyl alcohol as a preservative, but used a vehicle containing polysorbate 80, dibasic and monobasic sodium phosphate, polyglycol, and sodium chloride. Hida et al.30 in 1986 showed that the vehicle (including the preservative) of triamcinolone acetonide was nontoxic to the retina of rabbits even when injected in double strength, although the vehicles of betamethasone sodium phosphate, methylprednisolone acetate, dexamethasone acetate, and sodium phosphate caused retinal damage. We found in our study by two different assays that the vehicle itself was nontoxic to both ARPE-19 and R28 cells. This finding is in agreement with the results reported by Yeung et al.17 Also, in our study, triamcinolone acetonide with vehicle showed a trend of being more cytotoxic than did triamcinolone acetonide without the vehicle, although the difference was not statistically significant.
This study shows that triamcinolone acetonide in the Kenalog formulation (Bristol-Meyers Squibb) is toxic to retinal cells at various concentrations at short exposure times, whereas the vehicle including the preservative benzyl alcohol is not toxic. However, the observation that triamcinolone without the vehicle was less toxic than triamcinolone with the vehicle suggests that the vehicle may have a potentiating effect on the toxicity of triamcinolone acetonide, although the mechanism is unknown. The concentrations used in this study cannot be directly extrapolated to clinical practice, as this study was performed in vitro, and also because the steroid does not distribute evenly in the vitreous gel due to its depot formulation. In addition, the cells used were still capable of proliferation, which is different from normal clinical conditions and may limit the interpretation of the results. Regardless, the results of this study suggest that clinically used doses of triamcinolone acetonide, with or without the vehicle may cause cytotoxicity in retinal neurosensory and pigment epithelial cells, potentially blunting the clinically observed benefit of triamcinolone acetonide.
| Footnotes |
|---|
Supported by Research to Prevent Blindness, The Discovery Eye Foundation, the Skirball Molecular Ophthalmology Program, and the Iris and B. Gerald Cantor Foundation.
Submitted for publication June 20, 2005; revised August 10, 2005; accepted December 5, 2005.
Disclosure: R. Narayanan, None; J.K. Mungcal, None; M.C. Kenney, None; G.M. Seigel, None; B.D. Kuppermann, None
The publication costs of this article were defrayed in part by page charge payment. This article must therefore be marked "advertisement" in accordance with 18 U.S.C.
1734 solely to indicate this fact.
Corresponding author: Baruch D. Kuppermann, UCI Department of Ophthalmology, 118 MedSurge I, Irvine, CA 92697; bdkupper{at}uci.edu.
| References |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
G Weigert, S Michels, S Sacu, A Varga, F Prager, W Geitzenauer, and U Schmidt-Erfurth Intravitreal bevacizumab (Avastin) therapy versus photodynamic therapy plus intravitreal triamcinolone for neovascular age-related macular degeneration: 6-month results of a prospective, randomised, controlled clinical study Br. J. Ophthalmol., March 1, 2008; 92(3): 356 - 360. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Lorenzo Carrero, M. Gonzalez Barcia, and I. Perez Flores Sterile Endophthalmitis After Benzyl Alcohol Filtered Triamcinolone Acetonide Injection Arch Ophthalmol, January 1, 2008; 126(1): 142 - 143. [Full Text] [PDF] |
||||
![]() |
H. Chung, J. J. Hwang, J. Y. Koh, J.-g. Kim, and Y. H. Yoon Triamcinolone Acetonide-Mediated Oxidative Injury in Retinal Cell Culture: Comparison with Dexamethasone Invest. Ophthalmol. Vis. Sci., December 1, 2007; 48(12): 5742 - 5749. [Abstract] [Full Text] [PDF] |
||||
![]() |
I. Kozak, L. Cheng, G. A. Silva, and W. R. Freeman Testing of Intraocular Drugs for Clinical Use Invest. Ophthalmol. Vis. Sci., November 1, 2007; 48(11): 4861 - 4863. [Full Text] [PDF] |
||||
![]() |
Y.-S. Chang, C.-L. Wu, S.-H. Tseng, P.-Y. Kuo, and S.-Y. Tseng Cytotoxicity of Triamcinolone Acetonide on Human Retinal Pigment Epithelial Cells Invest. Ophthalmol. Vis. Sci., June 1, 2007; 48(6): 2792 - 2798. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. Scorolli, M. Morara, A. Meduri, L. B. Reggiani, G. Ferreri, S. Z. Scalinci, and R. A. Meduri Treatment of Cystoid Macular Edema in Retinitis Pigmentosa With Intravitreal Triamcinolone Arch Ophthalmol, June 1, 2007; 125(6): 759 - 764. [Abstract] [Full Text] [PDF] |
||||
![]() |
R Obata, A Iriyama, Y Inoue, H Takahashi, Y Tamaki, and Y Yanagi Triamcinolone acetonide suppresses early proangiogenic response in retinal pigment epithelial cells after photodynamic therapy in vitro Br. J. Ophthalmol., January 1, 2007; 91(1): 100 - 104. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. E. Hartnett, D. J. Martiniuk, Y. Saito, P. Geisen, L. J. Peterson, and J. R. McColm Triamcinolone Reduces Neovascularization, Capillary Density and IGF-1 Receptor Phosphorylation in a Model of Oxygen-Induced Retinopathy Invest. Ophthalmol. Vis. Sci., November 1, 2006; 47(11): 4975 - 4982. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |