A two-step model of TiO2 nanoparticle toxicity in human liver tissue

- The cell-response model is proposed to study hepatotoxicity of TiO2 nanoparticles in the cellular level.
- The model explains how the cell population responds to the deposited nanoparticles.
- For low nanoparticle doses, tissue damage is negligible due to renewal through cell division.
- For larger doses, larger fractions of cells must participate in the cell cycle to recover the original tissue mass.

We examine the toxicity of titanium dioxide (TiO2) nanoparticles on human liver through a two-step approach, including a physiologically-based pharmacokinetic (PBPK) model and a cell-response model. The PBPK model predicts the bio-distribution of nanoparticles that remain in the human body after exposure, with special attention to their accumulation in liver tissue. The cell-response model predicts liver cell death as a consequence of the accumulated TiO2 nanoparticles by considering cell fate dynamics through the interplay between cellular uptake of the nanoparticles and their dilution due to cell division. The results suggest that tissue damage from a low nanoparticle dose is negligible due to renewal cell division, but for higher doses larger fractions of cells must participate in the cell cycle to recover the original tissue mass. By combining the two models, it becomes possible to explain the liver cell viability and cell death after TiO2 nanoparticle exposure.

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