Evaluation of E-cigarette liquid vapor and mainstream cigarette smoke after direct exposure of primary human bronchial epithelial cells

• Published in: International journal of environmental research and public health Vol. 12; no. 4; pp. 3915 - 3925
• Main Authors: Scheffler, Stefanie, Dieken, Hauke, Krischenowski, Olaf, Förster, Christine, Branscheid, Detlev, Aufderheide, Michaela
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 08.04.2015; MDPI
• Subjects: Bronchi - drug effects; Electronic cigarettes; Electronic Nicotine Delivery Systems - adverse effects; Epithelial Cells - drug effects; Health hazards; Humans; Nicotine - adverse effects; Public health; Smoke - adverse effects; Smoking
• ISSN: 1660-4601; 1661-7827; 1660-4601
• DOI: 10.3390/ijerph120403915

E-cigarettes are emerging products, often described as "reduced-risk" nicotine products or alternatives to combustible cigarettes. Many smokers switch to e-cigarettes to quit or significantly reduce smoking. However, no regulations for e-cigarettes are currently into force, so that the quality and safety of e-liquids is not necessarily guaranteed. We exposed primary human bronchial epithelial cells of two different donors to vapor of e-cigarette liquid with or without nicotine, vapor of the carrier substances propylene glycol and glycerol as well as to mainstream smoke of K3R4F research cigarettes. The exposure was done in a CULTEX® RFS compact  module, allowing the exposure of the cells at the air-liquid interface. 24 h post-exposure, cell viability and oxidative stress levels in the cells were analyzed. We found toxicological effects of e-cigarette vapor and the pure carrier substances, whereas the nicotine concentration did not have an effect on the cell viability. The viability of mainstream smoke cigarette exposed cells was 4.5-8 times lower and the oxidative stress levels 4.5-5 times higher than those of e-cigarette vapor exposed cells, depending on the donor. Our experimental setup delivered reproducible data and thus provides the opportunity for routine testing of e-cigarette liquids to ensure safety and quality for the user.