TiO2 Nanoparticles Induce Dysfunction and Activation of Human Endothelial Cells

Nanoparticles can reach the blood and cause inflammation, suggesting that nanoparticles-endothelial cells interactions may be pathogenically relevant. We evaluated the effect of titanium dioxide nanoparticles (TiO2) on proliferation, death, and responses related with inflammatory processes such as monocytic adhesion and expression of adhesion molecules' (E- and P-selectins, ICAM-1, VCAM-1, and PECAM-1) and with inflammatory molecules (tissue factor, angiotensin-II, VEGF, and oxidized LDL receptor-1) on human umbilical vein endothelial cells (HUVEC). We also evaluated the production of reactive oxygen species, nitric oxide production, and NF-kappa B pathway activation. Aggregates of TiO2 of 300 nm or smaller and individual nanopartides internalized into HUVEC inhibited proliferation strongly and induced apoptotic and necrotic death starting at 5 mu g/cm(2). Besides, TiO2 induced activation of HUVEC through an increase in adhesion and in expression of adhesion molecules and other molecules involved with the inflammatory process. These effects were associated with oxidative stress and NF-kappa B pathway activation. In conclusion, TiO2 induced HUVEC activation, inhibition of cell proliferation with increased cell death, and oxidative stress.