Jeremie Gafner , Christelle Lamboley , Louise Neilson
JT International SA, Scientific & Regulatory Affairs, Geneva, Switzerland
The study’s objective was to investigate the use of an air-liquid interface (ALI) exposure system to evaluate the biological response of 3D reconstructed human airway tissue (MucilAir™ from Epithelix, Geneva) when exposed to the aerosol of a commercialized waterpipe sample generated by the Vitrocell® waterpipe testing device combined with the Vitrocell® 12/6 exposure module system. These types of exposure systems have previously been extensively characterized for the evaluation of cigarettes and Reduced-Risk Tobacco Products (RRP) and shows promise in supplementing or replacing in vivo toxicity testing. As far as waterpipe aerosols are concerned, limited studies are available for their evaluation. To develop a method to evaluate waterpipe aerosols, one key step is to define a method to reliably estimate the dose deposited on cells. To this end, several methods are available and have been previously described (Miller-Holt et al. 2022). In this study, fluorescence trapped in a DMSO solution was assessed as a surrogate to assess waterpipe aerosol deposition since it was previously described as an easy, fast, and efficient way to assess exposure (Fields et al. 2017). A preliminary analysis was carried out to measure the fluorescence obtained from five different aerosol concentrations to select two concentrations resulting in a high and low exposure for the biological testing. However, fluorescence on its own does not provide any insight into an actual dose that could be used for in vitro extrapolation. Therefore, a filter pad was used to assess the fluorescence of Total Collected Matter (TCM). As a second step, a number of biological endpoints were measured following repeated exposure of waterpipe aerosol on MucilAir™ tissues, including the transepithelial electrical resistance (TEER), Lactate dehydrogenase (LDH) release, cell viability (Resazurin assay) and ciliary beating frequency (CBF).