Ethyl pyruvate treatment mitigates oxidative stress damage in cultured trabecular meshwork cells

PURPOSE Oxidative stress plays a key role in the pathophysiology of glaucoma. This study was designed to assess ethyl pyruvate (EP) as a novel antioxidative agent in cultured human trabecular meshwork (hTM) cells. METHODS Primary hTM cells were cultured on collagen matrices. Tolerance to EP was assessed at various concentrations using fluorescent vital dyes (live/dead) and metabolic (1-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays. After the candidate doses were identified, cells received either preincubation with EP before hydrogen peroxide stressing or pre- and coincubation with EP before and during stressing. Live/dead and metabolic activity assays were used to quantify oxidative damage. RESULTS Cultured hTM cells were well tolerant of EP concentrations at or below 10 mM while higher doses showed significant levels of cytotoxicity. In the peroxide stress assays, samples that received pre- and cotreatment with all concentrations of EP showed significantly increased cell survival and maintenance of metabolic activity. However, samples that received only pretreatment did not show a significant increase in survival rates and lost nearly all metabolic activity after peroxide-induced stressing. CONCLUSIONS This work suggests that EP is a potent antioxidant that is well tolerated by hTM cells; however, EP's potential as a therapeutic agent for glaucoma is limited by its inability to enhance endogenous antioxidant capacity. A continuous drug delivery system may be needed to realize the full therapeutic potential of EP for treatment of glaucoma.