Flavor-induced inflammation and cytotoxicity in human aortic smooth muscle cells: Potential implications for E-cigarette safety

Electronic nicotine delivery systems (ENDS), commonly known as e-cigarettes, are considered safer alternatives to tobacco smoking, yet their long-term health effects, particularly on cardiovascular health, remain unclear. The aim of this study was to investigate the cytotoxic and pro-inflammatory effects of device power, nicotine content and flavor molecules on human aortic smooth muscle cells. AoSMCs cells were exposed to e-liquids and e-cigarette aerosol condensates containing different ratios of propylene glycol (PG) and vegetable glycerin (VG), nicotine (0, 10, 20 mg/mL), and flavors (cinnamon, menthol, tobacco), with the devices operated at different power levels (10 W, 15 W, 25 W). After a 24 h incubation, cytotoxicity was evaluated using lactate dehydrogenase (LDH) release, while pro-inflammatory effects were measured by interleukin-8 (IL-8) production. The results showed no significant cytotoxicity or inflammation in cells exposed to PG/VG base or nicotine-containing e-liquids. However, e-liquids as well as aerosol condensates containing flavors induced significant increases in IL-8 production compared to controls without flavor. Moreover, the pro-inflammatory response was more pronounced in response to aerosol condensates than to the corresponding e-liquids. Cinnamon, in particular, produced the highest inflammatory response, and the effect was enhanced at higher power settings (25 W), which also induced cytotoxicity, particularly at high concentrations. These findings demonstrate that flavors, especially cinnamon, and device power levels are key factors influencing the inflammatory potential and cytotoxicity of e-cigarette aerosols. Further studies are needed to explore the long-term cardiovascular risks associated with ENDS use and the role of flavor molecules and of their thermal degradation products.