Aerosolized e‐liquid base constituents induce cytotoxicity and genotoxicity in oral keratinocytes

Abstract

AbstractObjectiveElectronic cigarette (e‐cigarette) use among adults in the United States continues to rise. Particularly concerning is the impact of e‐cigarette aerosol inhalation on the oral mucosa. Aerosols are derived from a heated e‐liquid base of propylene glycol/glycerin (PG/G) often mixed with nicotine and chemical flavors. Of note, harmful and potentially harmful constituents (HPHCs), including metals and volatile organic compounds, have been detected in e‐cigarette aerosols. It remains unknown, however, whether aerosols exclusively derived from e‐liquid PG/G are detrimental to oral keratinocytes. The present study analyzed toxicological outcomes in normal oral keratinocytes exposed to model nicotine‐free, unflavored PG/G e‐liquid aerosols.Materials and MethodsCell viability/cytotoxicity, genotoxicity, and immunoblotting assays were conducted in NOKSI, a gingiva‐derived oral keratinocyte cell line, following exposure to model e‐liquid aerosols or non‐aerosolized controls. The HPHC acrolein, reported to form DNA adducts in the buccal mucosa from e‐cigarette users, was also used in similar assays.ResultsPG/G e‐liquid aerosol extracts significantly enhanced cytotoxic and DNA damaging responses in NOKSI cells when compared to non‐aerosolized e‐liquid treatment. Acrolein treatment led to similar results.ConclusionsThe aerosolization process of PG/G e‐liquid is a critical determinant of marked cytotoxic and genotoxic stimuli in oral keratinocytes.