A 3D co-culture of three human cell lines to model the inflamed intestinal mucosa for safety testing of nanomaterials

Abstract

Oral exposure to nanomaterials is a current concern, asking for innovative biological test systems to assess their safety, especially also in conditions of inflammatory disorders. Aim of this study was to develop a 3D intestinal model, consisting of Caco-2 cells and two human immune cell lines, suitable to assess nanomaterial toxicity, in either healthy or diseased conditions. Human macrophages (THP-1) and human dendritic cells (MUTZ-3) were embedded in a collagen scaffold and seeded on the apical side of transwell inserts. Caco-2 cells were seeded on top of this layer, forming a 3D model of the intestinal mucosa. Toxicity of engineered nanoparticles (NM101 TiO₂, NM300 Ag, Au) was evaluated in non-inflamed and inflamed co-cultures, and also compared to non-inflamed Caco-2 monocultures. Inflammation was elicited by IL-1β, and interactions with engineered NPs were addressed by different endpoints. The 3D co-culture showed well preserved ultrastructure and significant barrier properties. Ag NPs were found to be more toxic than TiO₂ or Au NPs. But once inflamed with IL-1β, the co-cultures released higher amounts of IL-8 compared to Caco-2 monocultures. However, the cytotoxicity of Ag NPs was higher in Caco-2 monocultures than in 3D co-cultures. The naturally higher IL-8 production in the co-cultures was enhanced even further by the Ag NPs. This study shows that it is possible to mimic inflamed conditions in a 3D co-culture model of the intestinal mucosa. The fact that it is based on three easily available human cell lines makes this model valuable to study the safety of nanomaterials in the context of inflammation.

• Caco-2
• cytotoxicity
• intestine
• nanoparticles

Acknowledegments

We thank the Electron Microscopy Unit for Biological Sciences, Department of Biosciences, University of Oslo. Thanks to Dr Wolfgang Kreyling from Helmholtz Zentrum, Munich, for providing the 15 and 80 nm Au nanoparticles. Thanks to Prof. Vicki Stone and Dr Birgit Gaiser from Heriot-Watt University, Edinburgh, for helpful discussions about FACS results. We also thank Dr. Sarah Gordon from Helmholtz Institute for Pharmaceutical Research, Saarbrücken, for proof-reading the manuscript and Petra König (Helmholtz Institute for Pharmaceutical Research) and Marijas Jurisic (Saarland University) for their help in cell culture and FACS experiments.

Declaration of interest

This work was funded from the EU FP7 project InLiveTox (NMP4-SL-2009-228625).

Supplementary material available online

Supplementary Tables S1, S2 Figures S1-S7.