The retinal pigment epithelial (RPE) cell is exposed to chronic oxidative stress in part from exposure to high partial pressures of oxygen and in part, from its high level of oxygen

The retinal pigment epithelial (RPE) cell is exposed to chronic oxidative stress in part from exposure to high partial pressures of oxygen and in part, from its high level of oxygen metabolism which generates large amounts of reactive oxygen intermediates (ROI) [1,2]. Several in vitro models have been developed to study the effects of oxidative stress on RPE cells, but most of these utilize the acute, high level administration of a chemical oxidant [3,4]. While these chemical oxidants induce a specific cellular oxidative stress that is useful for studying cellular responses to individual ROIs, the applicability of these acute chemical effects to the in vivo condition is open to question. An alternative and perhaps more applicable approach to studying the effects of oxidative stress on RPE cells would apply chronic and lower levels of oxidative stress than the acute levels resulting from chemical oxidants. Recently, von Zglinicki et al. used chronic hyperoxia treatment to induce long term oxidative stress on lung fibroblasts [5]. The purpose of our study was to develop and characterize a model using chronic hyperoxia treatment of the RPE cell that induces mild oxidative stress without causing cell death. Our laboratory and others have studied in depth, the characteristics of one cell line, designated RPE340 [6-9]. In this study, we have utilized RPE340 cells, and compared their response to WI38 lung fibroblasts, a cell line that has been utilized in oxidative stress studies, for comparison.