Development of a gaseous exposure system to assess in vitro cytotoxicity of MucilAir™ tissues following exposure to airway irritants/non-irritants

LIVe 2024 -- This study was initiated to investigate a continuous flow gaseous exposure system to three gaseous compounds. There is a current push to investigate products in a more physiologically relevant environment (continuous flow versus static). 3D airway tissue models are a relevant method for analysis of toxicity for these gaseous products. These tissues have increased physiological relevance over monolayer cell cultures as they have attributes that represent the respective regions of the human respiratory tract that are generally only seen in vivo. MucilAir™ (Epithelix Sarl, Switzerland) tissues were exposed using a gaseous exposure system with Vitrocell® 24/4 modules to ethylene oxide (EtO), nitric oxide (NO) and sulphur hexafluoride (SF6) for a total of 60 minutes. Gas was diluted at varying concentration with flowing air and presented as parts per million (ppm). In this study, we used the lactate dehydrogenase (LDH) release, WST-8 (2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt), trans-epithelial electrical resistance (TEER), cilia beat frequency and a pro-inflammatory cytokine panel were used to assess cytotoxicity. Post-exposure tissues were left for 24hr recovery after treatment prior to analysis. EtO decreases greater than 50% versus concurrent control were observed for WST-8 and LDH, but not for NO or SF6. Significant changes were observed for CBF and TEER, but not for SF6. Significant increases/decreases were observed in cytokine release for all test articles. This study demonstrates the potential of the gaseous exposure system to differentiate between test articles exposed in a physiologically relevant environment and to provide insight into the different biological pathways affected.