Comparative in vitro and in ovo study of the cytotoxic profile of nicotine from electronic cigarettes versus chewing gum

This study aimed to assess and compare the cytotoxic and vascular effects of e-liquid used in electronic cigarette (e-liquid) and nicotine containing chewing gum (NCG) using in vitro models of keratinocytes and cardiomyocytes, as well as in ovo models using the chorioallantoic membrane of developing chicken embryos. In the in vitro experiments, both cell lines were exposed to e-liquid and NCG at similar and relevant concentrations for in vivo administration. The results demonstrated that e-liquid exerted a more pronounced cytotoxic impact when compared to NCG. E-liquid caused a significant decrease in cell viability (up to about 46%) and induced substantial alterations in cellular morphology and nuclei. This finding implies an elevated risk linked to the use of electronic cigarettes, emphasizing that the cumulative content of harmful substances in these devices, beyond nicotine, contributes to their potential adverse effects. Additionally, in the in ovo evaluation, e-liquid revealed alarming signs of vascular irritation, including haemorrhage, lysis and intravascular coagulation within the chorioallantoic membrane. These findings underscore the vascular and skin health risks associated with e-liquid, prompting a need for comprehensive investigation into the long-term consequences for users. As a conclusion, the study outcomes highlight that, in vitro, the eliquid used in electronic cigarette exerts heightened toxic effects on both keratinocytes and cardiomyocytes in comparison to the impact observed with nicotine containing chewing gum.