# Glia Cells Are Selectively Sensitive to Nanosized Titanium Dioxide Mineral Forms

## TL;DR

Nanosized titanium dioxide particles, especially rutile form, may harm specific brain cells like astroglia and microglia, raising concerns about their safety in consumer products.

## Contribution

The study reveals that rutile TiO2 nanoparticles selectively harm glial cells, depending on brain region and cell type.

## Key findings

- Rutile TiO2 nanoparticles caused cell death in cortical astroglia at concentrations above 10 µg/mL after 24 hours.
- Hippocampal astroglia and mixed neuron-glia cultures were less affected by rutile or anatase nanoparticles.
- Rutile nanoparticles also damaged microglial cells, suggesting a specific vulnerability to this cell type.

## Abstract

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.