Effects of hydroquinone on retinal and vascular cells in vitro

Aim: To explore the molecular pathophysiology that might explain the epidemiologic association between cigarette smoke and age-related macular degeneration (AMD) by examining the effects of hydroquinone (HQ), a toxic compound present in high concentration in cigarette smoke-related tar, on human retinal pigment epithelial cells (ARPE-19), rat retinal neurosensory cells (R-28), and human microvascular endothelial cells (HMVEC). Materials and Methods: ARPE-19, R-28, and HMVEC were treated for 24 h with four different concentrations of HQ (500 mu M, 200 mu M, 100 mu M, 50 mu M). Cell viability, caspase-3/7 activation, DNA laddering patterns, and lactate dehydrogenase (LDH) levels were analyzed. Results: At 50 mu M HQ, R-28 cells showed a significant decrease in cell viability compared with the dimethyl sulfoxide (DMSO)treated controls. At the 100-500 mu M concentrations, all three cell lines showed significant cell death (P < 0.001). In the ARPE-19, R-28, and HMVEC cultures, the caspase-3/7 activities were not increased at any of the HQ concentration. Conclusion: Our findings suggest that the mechanism of cell death in all three cell lines was through non-apoptotic pathway. In addition, neuroretinal R-28 cells were more sensitive to HQ than the ARPE-19 and HMVEC cultures.