New research by British American Tobacco comparing the effects of cigarette smoke and electronic cigarette vapor has shown that, at equivalent or higher doses of nicotine, acute exposure to electronic cigarette vapor has very limited impact on gene expression when compared to the impact of cigarette smoke.
A BAT press note said that the human genome had tens of thousands of genes, and that the profile of genes that were switched on and off could be used to understand whether exposure to an aerosol had had a toxic effect.
‘Scientists at British American Tobacco used nicotine as a reference point and exposed MucilAir™, a realistic in vitro 3D model of a human airway, to e-cigarette vapor and cigarette smoke to assess their comparative effect on gene expression,’ the press note said.
‘The MucilAir™ human respiratory tissue was exposed to smoke from a reference cigarette (3R4F) or vapor from an e-cigarette (Vype ePen) continuously for an hour. Two doses of vapor were tested, matching or doubling the amount of nicotine reaching the cells compared to smoke. Then, to measure the cell response, the scientists mapped the genes that were switched on and off at 24 hours and 48 hours after the one-hour exposure.
‘In the tissue exposed to smoke, the scientists found 873 and 205 genes were affected after 24 and 48 hours of recovery, respectively. However, significantly fewer genes – only 3 and 1, respectively – were affected after exposure to e-cigarette vapour.’
Further analysis was said to have revealed that the exposure to cigarette smoke had caused changes in the expression of genes involved in the development of lung cancer, inflammation and fibrosis, while the test electronic cigarette vapor had caused only minor changes in genes known to be involved in cell metabolism and oxidative stress mechanisms.
“Our results clearly show that cigarette smoke has an adverse effect on cells, triggering a robust gene expression response,’ said Dr. James Murphy, head of reduced risk substantiation at BAT. “However,” he said, “even at equivalent or higher dose of nicotine, acute exposure to the test e-cigarette vapor has very limited impact on gene expression compared to cigarette smoke exposure – it’s a striking difference.”
These results, which were published in Scientific Reports (DOI: 10.1038/s41598-017-00852-y), were said to add to an increasing weight of evidence that electronic cigarette vapor caused less damage to cells than did cigarette smoke.
‘Previous research conducted by British American Tobacco has shown that Vype ePen vapor contains around 95 percent less toxicants (Chem. Res. Toxicol, DOI: 10.1021/acs.chemrestox.6b00188) compared to cigarette smoke from a reference cigarette (in terms of the priority list of nine toxicants which the World Health Organization recommends to reduce),’ the press note said.