Evaluation of Differential Oral Cell-specific Responses to the E-cigarette Component Nicotine

Objectives: The recent introduction of electronic cigarettes (EC) or e-cigarettes, also known as the electronic nicotine delivery device (ENDD), has been promoted as a safer alternative to tobacco products and smoking. Many groups have advocated for the use of ECs or ENDDs as a tool to reduce carcinogenic potential, while simultaneously promoting strategies and protocols for smoking and nicotine cessation. Based upon this information, the main objective of this study was to determine the biological effects of the most basic aerosol component of all ECs and ENDDs (nicotine) on cells and tissues specifically derived from the oral cavity. The working hypothesis was that no discernable effects would be apparent at the concentrations typically associated with EC and ENDD use.

Experimental Methods: In brief, oral cell lines were obtained, which included normal, non-cancerous Human Gingival Fibroblasts (HGF-1) and two oral squamous cell carcinomas (SCC25, CAL27). Cells were exposed to nicotine at concentrations equivalent to those found in e-cigarette mixtures (5.77 x 10-5 M) for five day proliferation and viability assays.

Results: The results of this study strongly suggest that nicotine may have negative effects on both cellular viability and cellular proliferation among cancerous and non-cancerous cells. Moreover, these effects appear to become more pronounced over time, suggesting that short-term exposure to vaping solutions comprised of water with small amounts of nicotine may be sufficient to induce these effects – at least in this experimental or in vitro setting.

Conclusions: In summary, these data provide further evidence that nicotine administration may present significant risks to cell viability and growth over time. In addition, this study demonstrated that these effects were evident in both cancerous and non-cancerous cells – a finding that may suggest more research in this area is needed to determine the mechanisms that might be shared between these differing cell types, which may also suggest more caution may be needed when advertising or marketing ECs or ENDDs are low- or no-risk alternatives to cigarette smoking.