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Interest in the toxicological assessment of iterations of e-cigarette devices, e-liquid formulations and flavour use is increasing. Here, we describe a multiple test matrix and in vitro approach to assess the biological impact of differing e-cigarette activation mechanism (button vs. puff-activated) and heating technology (cotton vs. ceramic wick). The e-liquids selected for each device contained the same nicotine concentration and flavourings. We tested both e-liquid and aqueous extract of e-liquid aerosol using a high throughput cytotoxicity and genotoxicity screen. We also conducted whole aerosol assessment both in a reconstituted human airway lung tissue (MucilAir) with associated endpoint assessment (cytotoxicity, TEER, cilia beat frequency and active area) and an Ames whole aerosol assay with up to 900 consecutive undiluted puffs. Following this testing it is shown that the biological impact of these devices is similar, taking into consideration the limitations and capturing efficiencies of the different testing matrices. We have contextualised these responses against previous published reference cigarette data to establish the comparative reduction in response consistent with reduced risk potential of the e-cigarette products tested in this study as compared to conventional cigarettes.

We have developed a novel vaping product (NVP) IS1.0(TT), which utilises a stainless-steel mesh to transfer and vaporise the e-liquid, mitigating some of the potential sources of toxicants that can be generated using the more traditional ‘wick and coil’ approach. The emissions from IS1.0(TT) have previously been found to have lower levels of toxicants overall when directly compared with a commercial wick and coil e-cig. This current study assessed the toxicological responses to aerosols from this NVP. Responses induced by IS1.0(TT)were compared to those from a 3R4F reference cigarette, using in vitro test methods which included regulatory genetic toxicological assays as well as some more contemporary screening approaches. The experimental conditions were designed to facilitate the testing of aerosol from this vaping product at doses that in most cases greatly exceeded those of the 3R4F comparator showed little to no toxicological responses and demonstrated significantly reduced effects in these in vitro assays when compared to 3R4F. Furthermore, the extreme doses tested in the present study indicate that the toxicant profile of this NVP translates to lower biological activity in vitro, and suggests that the absolute risk hazard level associated with electronic cigarettes can be reduced through continuous improvement as the technology evolves.

Consumer demands and innovation have led to an increasingly diverse range of nicotine delivery systems, driven by a desire to reduce risk associated with traditional combustible cigarettes. This speed of change provides a mandate for rapid new product assessment. We have used the validated technology ToxTracker®, to assess biomarkers of DNA damage, protein misfolding, oxidative and cellular stress, across the categories of cigarette (1R6F), tobacco heating product (THP 1.4) and electronic cigarette (ePen 3). In addition, we compared the commonly used test matrices for tobacco and nicotine products; whole aerosol aqueous extracts (AqE) and gas vapour phase (GVP), determining their suitability across the product categories. We demonstrated a significant reduction in oxidative stress and cytotoxicity for THP 1.4 over cigarette, further reduced for ePen 3, when assessed by both dilution and nicotine dosimetry. We also identified that while the extraction matrices AqE and GVP from combustible products were equivalent in the induced responses, this was not true of the other category examples, moreover THP 1.4 GVP demonstrates a >50 % reduction in both toxicity and cytotoxicity endpoints over AqE. This indicates that unlike cigarette, the active components or toxicants for THP and electronic cigarette are associated with the aerosol fraction of these categories., (Copyright © 2022 The Author(s). Published by Elsevier B.V. All rights reserved.)

Thin spin-coated polymer films of amphiphilic copolymer obtained by partial acetalization of poly (vinyl alcohol) are used as humidity-sensitive media. They are deposited on polymer substrate (PET) in order to obtain a flexible humidity sensor. Pre-metallization of substrate is implemented for increasing the optical contrast of the sensor, thus improving the sensitivity. The morphology of the sensors is studied by surface profiling, while the transparency of the sensor is controlled by transmittance measurements. The sensing behavior is evaluated through monitoring of transmittance values at different levels of relative humidity gradually changing in the range 5-95% and the influence of up to 1000 bending deformations is estimated by determining the hysteresis and sensitivity of the flexible sensor after each set of deformations. The successful development of a flexible sensor for optical monitoring of humidity in a wide humidity range is demonstrated and discussed.

Isolated myofibers offer the possibility of in vitro study of satellite cells in their niche. We describe a mouse myofiber isolation assay to assess satellite cell activation by quantifying myofiber-derived satellite cell progeny. The assay allows isolation of myofibers from a mouse using standard equipment and reagents. It can be used to compare satellite cells across different mouse models or to evaluate their response to treatments, offering a valuable complementary tool for in vitro experimentation., Competing Interests: The authors declare no competing interests., (© 2021 The Author(s).)

Electronic cigarettes (e-cigarettes) and tobacco heating products (THPs) have reduced yields of toxicants and have recently emerged as a potentially safer alternative to combustible cigarettes. To understand if reduced toxicant exposure is associated with reductions in biological responses, there is a need for high-quality pre-clinical in vitro studies. Here, we investigated the cytotoxic response of human umbilical vein endothelial cells to conventional cigarette aqueous aerosol extracts (AqE) and highly concentrated AqEs from e-cigarettes (two generations of atomisers) and THPs (two variants). All AqE samples were generated by a standardized methodology and characterized for nicotine, propylene glycol and vegetable glycerol. The cigarette AqE caused a maximum 100 ± 0.00 % reduction in cell viability at 35 % dose (2.80 puffs) as opposed to 96.63 ± 2.73 % at 50 % (20 puffs) and 99.85 ± 0.23 % at 75 % (30 puffs) for the two THP variants (glo Bright Tobacco, glo Rich Tobacco), and 99.07 ± 1.61 % at the neat ePen2.0 e-cigarette (200 puffs). The AqE of the remaining e-cigarettes either resulted in an incomplete dose-response or did not elicit any response. The methods utilized were suitably sensitive to not only differentiate between cigarette, THP and e-cigarette aerosols but also to distinguish between products within each product category., Competing Interests: Declaration of Competing Interest The authors were employees of British American Tobacco at the time of study conduct. All experimental work was funded by British American Tobacco., (Copyright © 2020. Published by Elsevier B.V.)