A comparative study of toxicity of TiO 2 , ZnO, and Ag nanoparticles to human aortic smooth-muscle cells

Abstract

Purpose: To evaluate the adverse vascular effects of nanoparticles (NPs) in vitro, extensive studies have investigated the toxicity of NPs on endothelial cells, but the knowledge of potential toxicity on human smooth-muscle cells (SMCs) is currently limited. Methods: This study compared the toxicity of TiO 2 , ZnO, and Ag NPs to human aortic SMCs. Results: Only ZnO NPs significantly induced cytotoxicity, accompanied by increased intracellular reactive oxygen species, Zn ions, and endoplasmic reticulum stress biomarkers (DDIT3 expression and p-Chop proteins). All the NPs significantly promoted the release of soluble VCAM1 and soluble sICAM1, but not IL6, which suggested that metal-based NPs might promote inflammatory responses. Furthermore, KLF4 expression (a transcription factor for SMC-phenotype switch) was significantly induced by TiO 2 NPs and modestly by ZnO NPs, but the expression of CD68 remained unaltered. Conclusion: Our data indicated that ZnO NPs were more cytotoxic to human aortic SMCs than TiO 2 and Ag NPs at the same mass concentrations, which might have been associated with intracellular reactive oxygen species, Zn ions, and endoplasmic reticulum stress.