APOPTOSIS AND MORPHOLOGIC CHANGES IN DRUG-TREATED TRABECULAR MESHWORKCELLS IN-VITRO

Using an in vitro culture system, we investigated whether bovine trabe cuIar meshwork cells undergo apoptosis (programmed cell death) followi ng exposure to anti-glaucoma medications (timolol, pilocarpine and epi nephrine) and known inducers of apoptosis (5-fluorouracil, mitomycin-C and dexamethasone). Third to fifth passage bovine trabecular meshwork cells were grown to confluence and incubated for 1-12 days in growth media with timolol (1-1000 mu M), pilocarpine (15-15000 mu M), epineph rine (5-5000 mu M), 5-fluorouracil (10-100 mu g ml(-1)), mitomycin-C ( 0.01-100 mu g ml(-1)) and dexamethasone (0.01-100 mu M). The cultures were evaluated for apoptosis by phase-contrast microscopy, transmissio n electron microscopy and in situ apoptosis labeling. 5-Fluorouracil ( 10-100 mu g ml(-1)), mitomycin-C (0.1-100 mu g ml-l) and epinephrine ( 500-5000 mu M) induced apoptosis in a dose and time-dependent manner. Timolol, pilocarpine, and dexamethasone-treated specimens did not show evidence of apoptosis at any of the concentrations tested. Trabecular meshwork cells incubated in timolol (100-1000 mu M) developed cytopla smic granules, and specimens treated with pilocarpine (15000 mu M) dev eloped cytoplasmic vacuoles. These granules and vacuoles have the appe arance of secondary lysosomes. Dexamethasone-treated cells developed a n increased number of mitochondria. This study suggests that the trabe cular meshwork may undergo apoptosis following exposure to 5-fluoroura cil, mitomycin-C and epinephrine. Timolol, pilocarpine and dexamethaso ne did not induce apoptosis. However, these drugs can incite character istic morphologic changes in cultured trabecular meshwork cells. (C) 1 998 Academic Press Limited.