Abstract Rationale Although electronic cigarette (e-cigarette) vaping was initially considered a “safe” alternative to cigarette smoking, the relative lack of data on its health effects, compared with the abundant evidence of harm from cigarette smoking, has led to conflicting messages about vaping safety. E-cigarette liquid is typically composed of nicotine, propylene glycol (PG) and vegetable glycerol (VG), and mixtures of flavoring agents. This study aims to determine whether aerosolized nicotine and PG/VG lead to cell cytotoxicity, inflammation, and disruption of mucociliary clearance (MCC) in well differentiated primary human nasal epithelial cells (hNECs). Methods hNECs (n = 3) obtained by nasal brushings were expanded in culture and differentiated to a mucociliary phenotype at an air-liquid interface (ALI). After 28 days in ALI, using the University of North Carolina Vaping Product Exposure System (VaPES), hNECs were exposed to flavorless STLTH e-cigarette (Ontario, Canada) aerosol containing PG/VG with or without 20 mg/mL nicotine, while air controls were not exposed to any e-cigarette aerosol. Each condition was exposed for two weeks at a 6.5-second puff every five minutes, totaling 40 puffs per day. Following the exposure, apical washes were collected for lactate dehydrogenase (LDH) cytotoxicity assay, and basolateral media was collected and pooled every 7 days for IL-8 measurements by ELISA. Ciliary beat frequency (CBF) was measured using a Nikon Eclipse Ti2-E microscope and analyzed with the MATLAB-based Cilia-X software. Results After two weeks of exposure, hNECs released significantly more LDH in response to aerosolized PG/VG without nicotine than in air controls (P 0.05). PG/VG with nicotine induced higher IL-8 production than air controls during the second week of exposure. (P 0.05). There was no difference in CBF among the groups. Conclusions A 2-week exposure to aerosolized PG/VG with or without 20 mg/mL nicotine results in airway cell cytotoxicity and inflammation. However, there was no significant difference in CBF between e-cigarette exposure and controls. This is a pilot study with a limited sample size n = 3. Thus, we will recruit more subjects in future studies and will also investigate the effects of longer e-cigarette exposure on cell toxicity, inflammation, mucociliary clearance, and the underlying mechanisms. This abstract is funded by: PSI Foundation
Duan et al. (Fri,) studied this question.