an approach to testing undiluted e-cigarette aerosol in vitro using 3D reconstituted human airway epithelium

Introduction:
This article presents a study on the use of undiluted e-cigarette aerosol in vitro exposures for toxicological evaluation of e-cigarettes. The study compares the cytotoxic response of Mucilair cultures exposed to undiluted 3R4F cigarette smoke using two different standard smoking regimes, ISO and hCI. The authors also demonstrate the sensitivity of this exposure model and provide an acceptability benchmark for individual product risk assessment by testing an aerosol-based positive control.

Key Points:

* The study demonstrates that undiluted e-cigarette aerosol exposures can be used to generate a full cytotoxicity dose-response curve.
* The authors show a 7.5-fold difference in the absolute amount of sample deposited required for eBox aerosol to elicit a response, doubled to a 14-fold difference in exposure length.
* The study also demonstrates that undiluted aerosol generation is repeatable and reliable across independent experimental days.
* The authors found that the removal of diluting airflow did not affect the uniformity of aerosol delivery to each position in the module.
* The study shows that undiluted aerosol exposure conditions delivered significantly more nicotine dose to the aLI compared to traditional operating parameters.
* The results suggest that e-cigarette product differences and puffing regimes will change source aerosol nicotine concentration, even with the same e-liquid.
* The authors found that undiluted e-cigarette aerosols caused reductions in revertant numbers, indicating toxicity.

Main Message:
The study highlights the potential of undiluted e-cigarette aerosol exposures for toxicological evaluation of e-cigarettes. The authors demonstrate that undiluted aerosol exposures can generate a full cytotoxicity dose-response curve, and the removal of diluting airflow does not affect the uniformity of aerosol delivery to each position in the module. The study also shows that undiluted aerosol exposure conditions delivered significantly more nicotine dose to the aLI compared to traditional operating parameters. These findings suggest that in vitro exposure techniques should evolve to more accurately assess the effects of e-cigarette aerosols, as the products are different, and the same exposure principles for cigarette smoke testing do not necessarily apply to e-cigarette aerosol testing.

Bishop, E., L. haswell, J. adamson, S. Costigan, D. Thorne, and M. Gaca. “an approach to Testing Undiluted E-Cigarette aerosol in Vitro Using 3D Reconstituted human airway Epithelium.” Toxicology in Vitro 54 (February 2019): 391–401. https://doi.org/10.1016/j.tiv.2018.01.010.