Zinc Oxide Nanoparticles Induced Apoptosis and Necrosis in Human Neuroblastoma and Astrocytoma Cells

摘要

Because of their escalating uses in industrial and biomedical applications, humans are increasingly exposed to nanoparticles in occupational and other environmental settings. However, the environmental safety and health impact of such particles have not been elucidated. Previously, we have shown that many nanoparticles of metallic and non-metallic oxides exert cytotoxicity in human and other mammalian neural and non-neural cells. In this study, we have investigated the hypothesis that apoptosis is one mechanism underlying the toxicity of zinc oxide (ZnO) nanoparticles in human neuroblastoma SK-N-SH (neurons-like) and astrocytoma U87 (astrocytes-like) cells. Our results demonstrate the nanoparticles induced dose-related decreases in survival of both cell types. Furthermore, flow cytometric findings reveal that at higher treatment concentrations of 20-50 μg/mL of ZnO nanoparticles, both SK-N-SH and U87 cells were undergoing apoptosis and necrosis. However, significant proportions of SK-N-SH cells were at the late apoptotic state after treatment with the nanoparticles at 5, 10 and 25 μg/mL. Thus, our results strongly suggest both apoptosis and necrosis are cell death mechanisms underlying the differential cytotoxicity of ZnO nanoparticles in human neural SK-N-SH and U87 cells. As such they may have pathophysiological implications in the biocompatibility and health hazard of ZnO nanoparticles.