Objectives: The aim of this study was to compare the TiO2 NP uptake into an in vitro three-dimensional normal and cancer human oral mucosa model.
Methods: organotypic 3D cell culture models of two types - normal and cancer oral mucosa - were constructed in vitro. The normal model was created by using primary cells isolated from oral mucosa of healthy patients, while a model of oral cancer was build up by cancer cells (CaLH3 cell line). After 10 days of co-culture both models were exposed to 5 mg/l TiO2 NPs (spherical, 40nm, rutile, American Elements®, USA) for 24 hours. The models were then washed with Phosphate Buffer Saline, fixed in 4% formaldehyde for 24 hours, rinsed in distilled water, dehydrated and embedded in paraffin. Sections with a 3µm thickness were made and stained with H&E. Ultrahigh resolution imaging (URI) microscopy (CytoViva™, Auburn, USA) was used to assess the amount and depth of NPs penetration into reconstructed 3D tissues. Penetration depth was measured using the software Olympus DP.Soft 5.0.
Results: URI microscopy demonstrated similar uptake of TiO2 NPs in both normal and cancer models. NPs were located mainly within the epithelial part of both models. NPs penetrated deeper in the epithelium of the cancer (7,9 ± 5,14 µm) than of the normal models (2,9 ± 2,53 µm).
Conclusion: NP uptake and localization was similar in both normal and cancer reconstructed models of oral mucosa, while the penetration depth was higher in cancer models.