TiO2 nanoparticles disrupt cell adhesion and the architecture of cytoskeletal networks of human osteoblast-like cells in a size dependent manner.

Human exposure to titanium dioxide nanoparticles (nano-TiO2 ) is increasing. An internal source of nano-TiO2 is represented by titanium-based orthopedic and dental implants can release nanoparticles (NPs) upon abrasion. Little is known about how the size of NPs influences their interaction with cytoskeletal protein networks and the functional/homeostatic consequences that might follow at the implant-bone interface with regard to osteoblasts. We investigated the effects of size of anatase nano-TiO2 on SaOS-2 human osteoblast-like cells exposed to clinically relevant concentrations (0.05, 0.5, 5 mg/L) of 5 and 40 nm spherical nano-TiO2 . Cell viability and proliferation, adhesion, spread and migration were assessed, as well as the orientation of actin and microtubule cytoskeletal networks. The phosphorylation of focal adhesion kinase (p-FAKY397 ) and the expression of vinculin in response to nano-TiO2 were also assessed. Treatment with nano-TiO2 disrupted the actin and microtubule cytoskeletal networks leading to morphological modifications of SaOS-2 cells. The phosphorylation of p-FAKY397 and the expression of vinculin were also modified depending on the particle size, which affected cell adhesion. Consequently, the cell migration was significantly impaired in the 5 nm-exposed cells compared to unexposed cells. The present work shows that the orientation of cytoskeletal networks and the focal adhesion proteins and subsequently the adhesion, spread and migration of SaOS-2 cells were affected by the selected nano-TiO2 in a size dependent manner.