Comparison of in vitro safety profiles of vancomycin and cefuroxime on human corneal endothelial cells for intracameral use

Purpose: To evaluate and compare the cytotoxic and apoptotic properties of cefuroxime and vancomycin on cultured human corneal endothelial cells (HCECs) to determine their safety for intracameral use. Methods: Human corneal endothelial cells were harvested from human donor eyes and exposed to various concentrations of cefuroxime and vancomycin (0.15 to 15 mg/mL). For cytotoxicity testing, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test was performed. Annexin V binding combined with propidium iodide (PI) co-staining was used for the distinction of viable, early, and late apoptotic cells. Odds ratios (ORs) and confidence intervals were calculated for the control group (without drug exposure) for 2.75 mg/mL and 15 mg/mL. Cell morphology and immunolocalization of zonula occludens 1 (ZO1) were assessed after 24 hours of drug exposure. Results: Reduction in cell viability was observed in a dose-dependent manner after exposure to both drugs. Cefuroxime concentrations higher than 2.75 mg/mL and vancomycin concentrations higher than 5.0 mg/mL led to significant reduction in cell viability. The mean number of annexin V-positive and PI-positive cells was not significantly increased at 2.75 mg/mL for either antibiotic agent. After exposure to 15.0 mg/mL, however, the late apoptotic/necrotic cells predominated, with higher ORs indicating accelerated cell death. Increasing concentrations of both antibiotic agents resulted in fading immunopositivity for ZO1. Conclusions: These data suggest a dose-dependent toxicity of cefuroxime and vancomycin on HCECs in vitro with a narrow range of safety. Although the clinically used concentrations seem to be safe, slightly higher concentrations might induce irreversible cell death and thus should be avoided.