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

Abstract

The data presented here show that to provide an estimate of the relative cytotoxicity and therefore potency of e-cigarettes, 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 ICs 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 IC 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 e-liquid 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.

A Case Study for the Comparison ofIn VitroData Across Multiple Aerosol Exposure Studies with Extrapolation to Human Dose

“…Studies were selected on the basis of several key criteria: (1) data were generated solely from Kentucky 3R4F reference cigarettes; (2) International Organization for Standardization (ISO) guidelines for puffing regimens and cigarette conditioning [ISO, 1999, 2012] were used consistently throughout; (3) Azzopardi et al 2015 36 Neilson et al 2015 37 Bishop et al 2018 38…”

“…Cytotoxicity data from contrasting and independent whole smoke studies were analyzed and presented using a consistent measure of dose (lg/cm 2 deposited mass and mg nicotine). Data from four previously published studies [35][36][37][38] were reanalyzed and combined with a previously unpublished data set using a comparative study design. Cytotoxicity data were supplemented with newly measured deposited mass of undiluted cigarette smoke, specifically obtained for this study to characterize the dilution principle.…”

“…In brief, Studies 1-4 are reanalyzed data. [35][36][37][38] Study Five is previously unpublished data. All percentage mass deliveries and fold dilutions are based on newly obtained data ( Fig.…”

“…37 MucilAir (Epithelix Sàrl, Plan-les-Ouates, Switzerland) was of nasal origin, from a healthy nonsmoking female Caucasian donor (MD006501). 38 Smoke generation and exposure-Vitrocell VC 10 and VC 01…”

Incoming Flow Turbulence Reduction Increases the Efficiency of Aerosolized Medication Delivery to 3D Oral Mucosal Tissue Models.

“…In recent years progress has been made in constructing 3D tissue models and using them for various research and clinical applications [18][19][20][21]. This allowed for departure from the use of animal tissue models, and for obtaining data in realistic physiologic conditions [21][22][23][24][25][26][27].…”