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

January 15, 2018
E. Bishop, L. Haswell, J. Adamson, S. Costigan, D. Thorne, M. Gaca
British American Tobacco, R&D, Southampton, Hampshire SO15 8TL, UK

A reconstituted 3D human airway epithelium was exposed to undiluted aerosols at the air-liquid interface, using a Vitrocell VC 10 under ISO and HCI conditions. A 3R4F reference cigarette and a commercially available e-cigarette product were tested on their effect on CBF and TEER.

The data presented here show that to provide an estimate of the relative cytotoxicity and therefore potency of ecigarettes, undiluted aerosol techniques can be used. With the emergence of electronic nicotine delivery systems, fit-for-purpose in vitro screening methods are required. Reconstituted 3D human airway epithelium, was exposed to undiluted aerosols at the air-liquid interface, using a Vitrocell VC 10. TEER, cilia beat frequency and cytotoxic responses were assessed. Using two smoking regimes (ISO and HCI) a 3R4F reference cigarette, produced IC50s of 5.2 and 2.1 min, 1458 ng/mL and 1640 ng/ mL nicotine respectively. Using an open tank e-cigarette device, a full cytotoxicity dose-response curve was obtained giving an IC50 of 30 min with corresponding nicotine of 10,957 ng/mL, 6–14 times less cytotoxic than cigarette smoke.
A commonly used e-liquid flavourant cinnamaldehyde and known skin sensitizer was added to the standard eliquid formulation and used as an aerosolised positive control, at 0.1, 0.025, 0.01 and 0%, demonstrating a full dose response. The delivery of undiluted aerosols in vitro has resulted in increased method sensitivity, throughput and quantitative e-cigarette comparisons. A positive control aerosol generated from a ‘safe’ e-liquid benchmark can inform risk assessments on supportable levels of flavour ingredients.

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