67 5.13: Future Directions

Future Directions

Despite this study’s contribution to the vast enigma of the pathological mechanisms of e-cigarettes, many unknowns still remain. For instance, despite the high prevalence of THC e-liquid use among EVALI patients (CDC; Kalininskiy et al.), it is yet to be determined if THC augments the effects of nicotine or if it induces pathology through an alternate pathway (Kalininskiy et al.). Another constitutive element of e-liquids with a possibly toxic effect is vitamin E acetate (CDC). This compound was recently identified by the CDC as a potential toxin in e-liquids, as vitamin E acetate was detected in the pulmonary fluid samples of 100% of the hospitalized EVALI patients tested (Blount et al.; CDC). Future studies should quantify amounts of vitamin E acetate present in e-liquids, such as through high performance liquid chromatography (HPLC), and compare cellular effects of different concentrations (Bahl et al., 2012). The cellular responses to e-liquids containing THC or vitamin E acetate should be explored, perhaps beginning with e-cigarette aerosol within in vitro studies.

Future studies should focus on the constituent chemicals of e-cigarette aerosols, which are the route of exposure for users (Farsalinos et al.).

To expand beyond in vitro studies, researchers could conduct in vivo studies. For example, mice could be exposed to e-cigarettes via a method that is representative of human exposure: through aerosols, from both nicotine-free and nicotine containing electronic cigarettes. A novel, inexpensive exposure method could be utilized (Hilpert et al.). Additional groups of mice could be exposed to either room air or traditional cigarette smoke, to serve as negative and positive controls, respectively. This study model was used by Madison et al. to examine the effects of e-cigarettes on pulmonary macrophages (2019). After exposure, neural cells or lung respiratory epithelial cells could be harvested and analyzed for evidence of SIMH and oxidative stress.

If e-cigarette use has a detrimental effect on neural stem cells in vivo, this could increase incidence of neurodegenerative diseases among chronic e-cigarette users (Zahedi et al.). Following the accumulation of more evidence to support this relationship, a prospective study could be designed to follow both e-cigarette users and non-users and monitor differential incidence of neurodegenerative diseases. If this hypothesis were to be confirmed, this could inform public health prevention efforts and identify at-risk populations.