Effects of Media Captured Vaporized E-Liquid on Oral Epithelial Cells

Objectives: E-cigarette use is becoming increasingly popular as a form of “safer smoking”. While much is known about the harmful effects of cigarettes on oral tissues, there is less evidence on the effects of vaping on the oral cavity, specifically on the oral epithelium. The nature of vaping allows exposure to high levels of e-liquid combustion products, and there is research suggesting that these contain harmful molecules. A system was established to model the effects of e-cigarette byproducts on oral epithelial cells in the liquid-tissue interface of the oral cavity.
Methods: An apparatus was constructed which allowed controlled exposure of keratinocyte culture media to e-cigarette smoke. Briefly, this consisted of a Smok G-priv 4™ e-cigarette filled with 3% freebase nicotine e-liquid connected to a media chamber, which was supplied with negative pressure through a submerged outflow using a standard pump. This allowed controlled bursts of vaporized e-liquid to be ‘bubbled’ through the culture media. Media was exposed for varying numbers of 8 second ‘puffs’: 30, 5 and 1. Control media was left unexposed. Exposed and control media were then used to culture (OKF-4) cells. Cell vitality was assessed by Trypan blue staining and proliferative capacity by tracking population doublings over time.
Results: OKF-4 cells in control media maintained 92-95% viability. Cells in media exposed to 30 puffs died within 72 hours, showing 21% vitality and a highly disrupted morphology after 48 hours. Cells cultured in media exposed to 5 puffs showed disrupted morphology, 75% vitality after 48 hours, and high cell death within 6 days. Cells cultured in media exposed to 1 puff maintained similar vitality to controls, but demonstrated half of their proliferation over 6 days.
Conclusions: E-cigarette vapor captured in culture media has exposure-level determined deleterious effects on the vitality and proliferative capacity of OKF-4 Cells.