Cytotoxicity, Mutagenicity and Genotoxicity of Electronic Cigarettes Emission Aerosols Compared to Cigarette Smoke: the REPLICA project

During the last decade electronic cigarettes (e-cigarettes) have been studied as an alternative devices to the tobacco cigarette, but with better safety for the health of smokers, so as to create a new approach to smoking addiction, such as the “smoking harm reduction”. This new approach, suggested by a part of the scientific world, aroused interest and debates in the regulatory field, involving all the major regulatory bodies and often creating divergences from nation to nation on the rules driving the production, distribution and consumption of these alternative products. Many studies have been conducted both in vitro and in vivo, to clarify the effects of the e-cigarette compared to the classic one. In this context, the Center of Excellence for the Acceleration of HArm Reduction (CoEHAR) was established within the University of Catania (Italy) and the multi-center project, created under its leadership, the REPLICA project, which aims to replicate in vitro studies originally conducted by tobacco and e-cigarette manufacturers, in order to verify the robustness and replicability of the data. In this work the REPLICA Team replicated part of the work published by Rudd and colleagues in 2020, which aims to establish the aerosol-induced cytotoxicity, mutagenesis and genotoxicity of a pod system e-cigarette aerosol compared to tobacco cigarette smoke. As in the original paper, we performed Neutral Red Test (NRU) for the evaluation of cytotoxicity, AMES test for the evaluation of mutagenesis and In Vitro Micronuclei (IVM) assay for the evaluation of genotoxicity on cells treated with cigarette smoke or e-cigarette aerosol. The results obtained showed high cytotoxicity, mutagenicity and genotoxicity induced by cigarette smoke, but slight or no cytotoxic, mutagenic and genotoxic effects induced by the e-cigarette aerosol. The data obtained support those previously presented by Rudd and colleagues, although we have highlighted some methodological flaws of their work. Overall, we can affirm that the results obtained by Rudd and colleagues have been established and our data also confirm the idea that e-cigarette aerosol is much safer and less harmful than e-cigarette smoking, making it a useful device in smoking harm reduction.