Influence of silica particle internalization on adhesion and migration of human dermal fibroblasts

In spite of significant advantages exhibiting in the applications of silicon dioxide particles in biological and medicine fields, their adverse effects still remain a big concern. Herein monodisperse spherical SiO2 particles with diameters of 80 nm and 500 nm were used to study their interactions with human dermal fibroblasts. Both the particles were readily internalized into the fibroblasts within a short time. The 500 nm particles were taken up in a larger amount through macropinocytosis and clathrin-mediated endocytosis pathways, whereas uptake of the 80 nm SiO2 particles was mediated corporately by macropinocytosis, clathrin-mediated and caveolae-mediated endocytosis. The particles mainly dispersed in the cytoplasm or resided within the lysosomal vesicles, but could not enter into the cell nucleus within 24 h culture in vitro. Treatment with the 80 nm SiO2 particles caused apparently decrease of cell viability and also weakened the mitochondrial membrane potential. Further experiments demonstrated that the cell adhesion and migration were greatly affected by uptake of the SiO2 particles regardless of their size. RT-PCR results indicated down regulation of the mRNA expression of adhesion relevant genes, i.e. fibronectin, laminin and focal adhesion kinase (FAK).