Glia Cells Are Selectively Sensitive to Nanosized Titanium Dioxide Mineral Forms

Nanosized titanium dioxide is widely used by the industry, e.g., in pigments, suncreams, and food colors. Its environmental and biological effects have been investigated in the past; however, few studiesd have focused on its crystal structure-specific effects. In our experiments, the toxicity of two types of synthetic nanoparticles was examined on primary neural cultures with different cell compositions using MTT and LDH assays. Primary murine cell cultures containing only astroglia cells originated from two brain regions, as well as mixed neurons and glia cells or microglia cells exclusively, were treated with anatase (15.8 ± 1.7 nm average diameter) and rutile (46.7 ± 2.2 nm average length and 13.7 ± 0.7 nm average diameter) TiO₂ nanoparticles at varying concentrations for 24 or 48 h. Our results show that neither anatase nor rutile nanoparticles reduced viability in cell cultures containing a mixture of neurons and glial cells, independently of the applied concentration and treatment time. Rutile but not anatase form induced cell death in cortical astroglia cultures already at 24 h of treatment above 10 µg/mL, while hippocampus-derived glial cultures were much less sensitive to rutile. The rutile form also damaged microglia. These findings suggest that products containing rutile-form nano-titanium particles may pose a targeted risk to astroglia and microglial cells in the central nervous system.