Next generation product aerosol bubbled extracts show little to no effect in high content screening endpoints when compared to cigarette smoke bubbled extracts
Tobacco-based and tobacco-free next generation products (NGPs) are understood to be a less harmful alternative to conventional combustible cigarettes.
The objective of this study was to compare the in vitro biological response of cigarette smoke and a selection of NGP aerosols bubbled through Phosphate Buffered Saline (PBS). Normal Human Bronchial Epithelial cells were exposed to smoke/aerosol in PBS from Kentucky reference cigarette (3R4F), a tobacco heating product (THP), a hybrid product (HYB) and a myblu™ e-cigarette (Tobacco Flavour 1.6 % Nicotine). In vitro response of each extract was determined after 4 and 24 hours exposure using high content screening.
The 3R4F and THP were smoked using the Health Canada Intense method. HYB and myblu™ were vaped according to CRM 81. The smoke and aerosols were bubbled through a series of three impingers containing PBS. For every test day, fresh PBS solutions with 1.8 puffs/ml and 4 puffs/ml for the 3R4F and NGP samples respectively were produced. Chemical analysis of the 3R4F PBS solutions detected nicotine with an average of 86 ± 12 µg/ml. The three NGP solutions contained nicotine levels from 70 ± 1 µg/ml (HYB), over 150 ± 17 µg/ml (THP) to 175 ± 17 µg/ml (myblu™).
The 3R4F smoke/aerosol in PBS caused a significant dose dependent decrease in cell count and significantly altered y-H2AX, NfKB, p-c-Jun and oxidative stress endpoints (at concentrations > 1 %). The THP solution induced a few similar endpoints to 3R4F, however the concentration of THP used to produce a response was considerably higher (2-4-fold) with lower effect (2-3 fold) than with 3R4F. By contrast, myblu™ and HYB extracts did not induce any significant activity in all the parameters tested at the maximum concentration used (10 % for THP, max of 4 % for 3R4F).
This data suggests that the extracts from NGPs elicit little to no in vitro biological activity, even at higher exposure concentrations, compared to combustible cigarettes under the conditions tested.