Size-Dependent Cytotoxicity and Reactive Oxygen Species of Cerium Oxide Nanoparticles in Human Retinal Pigment Epithelia Cells

PURPOSE: The use of cerium oxide nanoparticles (CeO(2) NPs), a lanthanide element oxide and bivalent compound, has been growing continuously in industry and biomedicine. Due to their wide application, the potential human health problems of CeO(2) NPs have attracted attention, but studies on the toxicity of this compound to human eyes are lacking. This study investigated the cytotoxicity and reactive oxygen species (ROS) of CeO(2) NPs in human retinal pigment epithelial cells (ARPE-19 cells). METHODS: Using the transmission electron microscope (TEM), the size distribution and shape of CeO(2) NPs were characterized. To explore the effect of CeO(2) NP size on ophthalmic toxicity in vitro, three sizes (15, 30 and 45 nm) of CeO(2) NPs were investigated using ATP content measurement, LDH release measurement and cell proliferation assay in ARPE-19 cells. ROS values and mitochondrial membrane potential depolarization were evaluated by H(2)DCF-DA staining and JC-1 staining. Morphology changes were detected using a phase-contrast microscope. RESULTS: The cytotoxicity of 15 nm CeO(2) NPs was found to be the highest and hence was further explored. Treatment with 15 nm CeO(2) NPs caused the morphology of ARPE-19 cells to change in a dose- and time-dependent manner. Moreover, the treatment induced excessive ROS generation and mitochondrial membrane potential depolarization. In addition, cytotoxicity was attenuated by the application of a ROS scavenger N-acetyl-L- cysteine (NAC). CONCLUSION: CeO(2) NPs induced cytotoxicity in ARPE-19 cells and excessive production of ROS and decreasing mitochondrial membrane potential. The Overproduction of ROS partially contributes to CeO(2) NP-induced cytotoxicity.