Savvina Chortarea,1 Hana Barosova,1 Martin James David Clift,2 Peter Wick,3 Alke Petri-Fink,1,4 and Barbara Rothen-Rutishauser,1
1BioNanomaterials, Adolphe Merkle Institute, University of Fribourg, CH-1700 Fribourg, Switzerland
2In Vitro Toxicology Group, Swansea University Medical School, Swansea SA2 8PP, Wales, U.K.
3Laboratory for Materials-Biology Interactions, Empa, Swiss Federal Laboratories for Materials, Science and Technology, 9014 St Gallen, Switzerland
4Department of Chemistry, University of Fribourg, CH-1700 Fribourg, Switzerland
The aim of this study was to realistically mimic subchronic inhalation of multiwalled carbone nanotubes in vitro, using the air−liquid interface cell exposure system for aerosol exposures on reconstituted human bronchial tissue from healthy and asthmatic donors. Cytotoxicity, cell morphology, cilia beating frequency, mucociliary clearance, gene expression analysis of oxidative stress and (pro‑)inflammatory markers as well as (pro‑)inflammatory cytokine secretion were successfully observed.
Although acute pulmonary toxicity of carbon nanotubes (CNTs) has been extensively investigated, the knowledge of potential health effects following chronic occupational exposure is currently limited and based only upon in vivo approaches. Our aim was to realistically mimic subchronic inhalation of multiwalled CNTs (MWCNTs) in vitro, using the air−liquid interface cell exposure (ALICE) system for aerosol exposures on reconstituted human bronchial tissue from healthy and asthmatic donors. The reliablity and sensitivity of the system were validated using crystalline quartz (DQ12), which elicited an increased (pro‑)inflammatory response, as reported in vivo. At the administrated MWCNT doses relevant to human occupational lifetime exposure (10 μg/cm2 for 5 weeks of repeated exposures/5 days per week) elevated cilia beating frequency (in both epithelial cultures), and mucociliary clearance (in asthmatic cells only) occurred, whereas no cytotoxic reactions or morphological changes were observed. However, chronic MWCNT exposure did induce an evident (pro‑)inflammatory and oxidative stress response in both healthy and asthmatic cells. The latter revealed stronger and more durable long-term effects compared to healthy cells, indicating that individuals with asthma may be more susceptible to adverse effects from chronic MWCNT exposure. Our results highlight the power of occupationally relevant subchronic exposures on human in vitro models in nanosafety hazard assessment.