Abstract:

To investigate the cytotoxicity of silica nanoparticles on vascular endothelial cells,and to clarify its action mechanism.Methods The 60 nm silica nanoparticle was selected and the in vitro cultured human umbilical vein endothelial cells (HUVECs) were used as cell model.The HUVECs  were divided into control and silica nanoparticle exposure groups with  concentrations of 12.5,25.0， and 100.00 mg•L^-1.MTT assay was used for the determination of cell viability,lactate dehydrogenase (LDH) release assay for membrane integrity,flow cytometry (FCM) for intracellular reactive oxygen species (ROS) content,and real-time PCR assay for intracellular NF-E2-related factor 2 (Nrf2),heme oxygenase-1 (HO-1),superoxide  dismutase 2 (SOD2) and glutamate-cysteine ligase catalytic subunit (GCLC) mRNA levels.Results The MTT results showed that the cell viabilities in each silica nnaoparticle exposure group were decreased compared with control group in a dose-dependent manner.Upon the silica nanoparticle exposure for 12 h,the cell viability was declined significantly only in 100 mg•L^-1 exposure group compared with control group (P<0.05).When  exposured for 24 h,the cell viabilities in 25.0,50.0, and 100.0 mg•L^-1 exposure groups were declined significantly  compared with control group (P<0.05).Under the exposure to silica nanoparticle with the same dose,the cell viabilities were decreased along with the elongation of exposure time. LDH assay and FCM showed that except for that in 12.5 mg•L^-1 exposure group,both the LDH activities in media and intracellular ROS levels in other exposure groups were increased compared with control group (P<0.05).The results of real-time fluorescence PCR showed that the mRNA levels of Nrf2,HO-1,SOD2 and GCLC in  100 mg•L^-1 silica nanoparticle exposure group were increased significantly compared with control group (P<0.05).Conclusion Silica nanoparticles have toxicity to vascular endothelial cells,which includes reducing cell viability,membrane integrity destruction,induction of ROS generation,and tranSCriptional regulation of redox-related factors.Oxidative damage is one of the mechanisms of vascular endothelial toxicity mediated by silica nanoparticles.
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Key words: silica nanoparticle, cytotoxicity, oxidative damage, reactive oxygen species, vascular endothelial cells