Overview of in vitro methods used to assess e-cigarettes based on “Toxicity Testing in 21st Century” principles
When the National Academies of Sciences released “Toxicity Testing in the 21st Century: A Vision and a Strategy” a new toxicological paradigm was created, focusing on the use of human cell lines and the disruption of key cellular pathways. In keeping with these principles we have sought novel assays for the biological assessment of our products. Due to the evolving regulatory landscape and dynamic nature of innovation with e-cigarettes, new assays are required to quickly determine the subtle biological response of these products for stewardship purposes. The published literature reveals that e-cigarette aerosols display a lack of significant cytotoxic and genotoxic responses in the CORESTA in vitro test battery.
For the stewardship of novel e-liquid ingredients, we screen all ingredients for carcinogenic, mutagenic and reproductive (CMR) properties and respiratory sensitising potential, from the scientific literature or using in silico predictions. If no major alerts are detected, the ingredients are assessed in a panel of biologically relevant assays. Examples of these assays include High Content Screening (HCS), in vitro human cell biomarkers, dermal sensitisation and irritation assays. Should assessment of the e-cigarette aerosol be required, 3D lung cell models can be exposed at the air-liquid interface to understand cytotoxic, inflammatory and oxidative response of the aerosol.
This presentation will discuss the various methods described above and will present some of the data generated so far for e-liquids with or without nicotine and the impact of flavours. Briefly, we have observed that lung cells employed in HCS and in in vitro human cell biomarker assay can detect increases in nicotine concentration in an e-liquid formulation. Moreover, characteristic fingerprint responses have been detected for certain e-liquid flavours, suggesting that flavours can play a role in the in vitro biological responses. These assays can greatly contribute to our current knowledge of e-liquid ingredients and aerosols and should form part of a weight of evidence approach for the assessment of this category of products.