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

Introduction:
This article presents a study on the adaptation of a Vitrocell VC 10 smoking robot to generate and deliver undiluted cigarette and e-cigarette aerosol to ALI respiratory cultures. The study compares the aerosol concentration of diluted and undiluted cigarettes and e-cigarettes and assesses the cytotoxicity of e-cigarette aerosol with and without the addition of a flavour compound. The study aims to increase the sensitivity of the ALI-exposed 3D reconstituted human airway tissue model to differentiate responses from aerosols produced from different e-liquids.

Key Points:

* The study used a Vitrocell VC 10 smoking robot to expose 3D respiratory tissues to undiluted cigarette and e-cigarette aerosols.
* The concentration of aerosol was a fixed parameter, with duration of exposure being the controlling variable.
* The study compared the nicotine delivery between products and across different smoking regimes.
* The study assessed the cytotoxicity of e-cigarette aerosol with and without the addition of a flavour compound.
* The study found that there is a significant difference in deposited nicotine concentration between diluted and undiluted aerosol for both cigarettes and e-cigarettes.
* The study found that the eBox e-cigarette aerosol showed an IC 50 at 30 minutes exposure, whereas 3R4F cigarette smoke demonstrated an IC 50 within 2.1 minutes of exposure.
* The study found that the addition of cinnamaldehyde to the e-liquid standard formulation resulted in an 80% loss of cell viability.

Main Message:
The study demonstrates the feasibility of generating and delivering undiluted aerosols from cigarette and e-cigarettes using a Vitrocell VC 10 smoking robot. The study highlights the potential of using undiluted aerosols to increase the sensitivity of the ALI-exposed 3D reconstituted human airway tissue model to differentiate responses from aerosols produced from different e-liquids. The study also suggests that the use of a 'safe benchmark' can inform what are supportable levels of flavour ingredients from a respiratory irritation and local cellular acute toxicity perspective. Overall, the study provides valuable insights for regulatory agencies and the e-cigarette industry to ensure the safety and quality of e-cigarette products.

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.