Purpose
Cefuroxime is used to prevent postoperative endophthalmitis, commonly at the intracameral dose of 1 mg/mL at the end of cataract surgery. For its application in vitroretinal surgery, this study investigated cefuroxime toxicity in human retinal pigment epithelium (RPE) cells.
Methods
Cultured human ARPE-19 cells were exposed to culture medium alone (control) or with cefuroxime (0.25, 0.75, 2.5, 7.5, 25, 75, or 250 mg/mL) for 1, 2, 6, or 24 hours. Cytoxicity was assessed by trypan blue staining, viability, TUNEL staining, propidium iodide/annexin V-FITC staining, caspase inhibition assay, and TEM.
Results
On the trypan blue staining, exposure to 0.75 mg/mL cefuroxime for 24 hours resulted in dead and shrunken RPE cells; the numbers increased in a dose- and time-dependent manner. On the viability assay, exposure to 0.25 mg/mL cefuroxime for 24 hours or 25 mg/mL for 1 hour impaired the mitochondrial function. On the TUNEL staining, exposure to 7.5 or 25 mg/mL cefuroxime caused DNA fragmentation, characteristic of late apoptosis. On the propidium iodide/annexin V-FITC staining and flow cytometry, cefuroxime led to dose- and time-dependent cell death by both apoptosis (more) and necrosis (less). On the caspase inhibition assay, pre-treatment with inhibitors of caspase-1, 2, 3, or 9 reduced the percentages of apoptotic cells, as well as reduced by cyclosporine A, a mitochondrial stabilizer. Ultrastructural study showed that exposure to 2.5 mg/mL cefuroxime for 24 hours lead to swollen organelles, and higher concentrations induced remarkable swelling, disorganization of organelles, disruption of cell membranes, and cell lysis.
Conclusions
Cefuroxime causes time- and dose-dependent damage to RPE cells by apoptosis and necrosis. One of the apoptotic pathways is via caspase-2, mitochondria, and caspase-3. Ultrastructure and mitochondria function are impaired within 24 hours. Exposure to 2.5 mg/mL cefuroxime, the commonly used intracameral concentration, is detrimental to RPE cells. We recommend safety precautions to decrease the risk of RPE toxicity.