AIM: To examine the effect of timolol maleate, a topical anti-glaucoma drug, on in vitro cultured human corneal endothelial(HCE)cells and lay foundations for its secure medication clinically.

METHODS: After in vitro cultured HCE cells treated with timolol maleate at different concentrations, the situation of cellular growth, proliferation, and morphology was checked under an inverted light microscope. And plasma membrane permeability, DNA fragmentations, and ultra-structure of HCE cells were detected by acridine orange/ethidium bromide(AO/EB)double fluorescent staining, DNA agarose gel electrophoresis, and transmission electron microscopy(TEM), respectively.

RESULTS: After treated with timolol maleate at concentrations from 0.15625g/L to 5g/L, in vitro cultured HCE cells showed typical characteristics of apoptosis, including growth retarding, number decreasing, cytoplasmic shrinking, vacuolation, falling off from well bottom of culture plate, plasma membrane permeability increasing, chromatin condensation, DNA fragmentation, appearance of apoptotic body, and so on. The apoptosis-inducing effect of timolol maleate was in dose- and time-dependent manners. The greatest apoptosis-inducing effect of timolol maleate on HCE cells was found at the clinic medication concentration of 2.5-5g/L, and their induced apoptotic rate of HCE cells at 28 hours reached 83.23%-96.71%, respectively.

CONCLUSION: Timolol maleate within the concentration of 0.15625-5g/L has an obvious apoptosis-inducing effect on HCE cells, and has tremendous toxicity to HCE cells at clinic medication dosage. Timolol maleate should be carefully utilized in ophthalmic clinic.