Comparison of in vitro toxicity of aerosolized engineered nanomaterials using air-liquid interface mono-culture and co-culture models

February 25, 2020


Yifang Wanga, Andrea,Adamcakova-Doddb, Benjamin R.Steinesb, Xuefang Jingb, Aliasger K.Salemc, Peter S.Thorneab
a Human Toxicology Interdisciplinary Program, University of Iowa, Iowa City, IA, USA
b Occupational and Environmental Health, University of Iowa, Iowa City, IA, USA
c College of Pharmacy, University of Iowa, Iowa City, IA, USA


• An in vitro co-culture model utilizing endothelial and epithelial cells and differentiated macrophages was established.
• Air-liquid interface exposures to Ag-SiO2 and CuO nanoparticles produced cell death, oxidative stress and cytokine release.
• Mono- and co-culture models showed comparable excposure outcomes except that cytokines were higher in the co-culture system.
• Compared to epithelia cells or macrophages alone, responses to CuO in the co-culture model indicated cellular interaction


Airborne engineered nanomaterials (ENMs) can readily enter the human body through inhalation potentially leading to adverse health effects such as cardiovascular and pulmonary diseases. Our group has previously utilized and validated an integrated low flow system capable of generating and depositing airborne ENMs directly onto cells at an air-liquid interface (ALI). To further improve this ALI method for an even closer representation of the in vivo system, a co-culture model containing epithelial, endothelial and macrophage cell lines (A549, EA.hy 926, and THP-1 differentiated macrophages) was established and validated for testing ENMs toxicity. In the co-culture model, cells were exposed to citrate-capped gold (Au), 15% silver on silica (Ag-SiO2) and copper oxide (CuO) ENMs under the same protocol (4 h ALI exposure with a target concentration of 3.5 mg/m3) and compared to responses with A549 cells only or THP-1 differentiated cells only. The toxicological profile was assessed by measuring cell viability, reactive oxygen species (ROS) production, lactate dehydrogenase (LDH) release, and interleukin (IL)-8 concentration. Results showed that 15% Ag-SiO2 induced more oxidative stress-related toxicity in the co-culture than in A549 cells alone. Both 15% Ag-SiO2 and CuO exposure produced significantly higher levels of IL-8 in the co-culture compared with A549 cells alone. Citrate-capped Au was largely inert. Further exposures of CuO on macrophages alone provided evidence of cell-cell interaction in the co-culture model. In addition, the co-culture model exhibited a similar response to primary human bronchial epithelial cells in terms of ROS and IL-8 responses after CuO exposure, suggesting a more advanced refinement of the conventional model for in vitro inhalation study.

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