Six hours of exposure to cigarette smoke resulted in almost complete death of tested cells while the same exposure to e-cigarette vapor did not affect tissue viability.
Tested from two different types of e-cigarettes, the vapor produced had no cytotoxic impact on human respiratory tract tissue, according to a new published in vitro toxicology study (DOI: 10.1016 / j.tiv .2015.05.018).
Scientists British American Tobacco et MatTek Corporation used a unique combination of tests to study the potential adverse effects of the vapor produced by the e-cigarette on the airway tissue and compared it to cigarette smoke. "Using a smoke machine and a laboratory-based test using respiratory tissue, it was possible to measure the irritancy of an aerosol and to prove that the various aerosols present in the e-cigarette used in this study have no effect cytotoxic on respiratory tract tissues in humans "Says the spokesman Dr. Marina Murphy.
This new method could be used to help develop new standards for these types of products in the future.
The vapor produced by the e-cigarette may contain nicotine, humectants, flavorings and products resulting from thermal degradation, so it is important to understand the potential impact on biological systems. Until now, there have been no studies proving potential adverse effects of e-cigarette vapor on in vitro models used that perfectly mimic the structure, function and exposure of normal human respiratory tissues.
The researchers combined an 3D model of commercially available respiratory epithelial tissue and the "Vitrocell" robot usually used for this type of test with "smoke" to evaluate the irritation potential of e-cigarette vapor two models available commercially. The results show that, despite hours of continuous exposure, the impact of e-cigarette vapor on the airway tissue is similar to that of air. In addition, the study represents an initial move towards socialization and launches the debate on potential guidelines for the industry.
The airway tissue model " EpiAirway Includes human tracheal / bronchial epithelial cells that have been cultured to form differentiated layers resembling epithelial tissue of the respiratory tract. The system " Vitrocell Mimics the exposure of an inhalant human by providing data on produced emissions of cigarettes or e-cigarettes. It can also simply return the inhalation to the tissues EpiAirway".
The researchers first tested the biological system with known irritants applied in a liquid form. Then they exposed the tissues EpiAirway cigarette smoke and aerosols generated from two types of e-cigarettes for six hours. Meanwhile, cell viability was measured every hour using an established colorimetric test. The amount of mass of particles deposited on the cell surface was also quantified (using dosimetry tools) to prove that smoke or vapor reached the tissue throughout the exposure.
The results show that the cigarette smoke reduces cell viability to 12% (close to complete cell death) after six hours. In contrast, none of the e-cigarette aerosols showed any significant decrease in cell viability. Despite 6 hours of continuous exposure, the results were similar to those of control cells exposed only to air . And even with aggressive exposure, vapors of e-cigarettes do not reduce cell viability.
«Currently, there are no standards for in vitro e-cigarette aerosol tests.says Marina Trani, head of R & D for nicotine products of the next generation of British American Tobacco. But, she adds, "Our protocol could be very useful in helping the process to progress.»
This study shows that in this model of human respiratory tissue, cytotoxicity is not affected by e-cigarette aerosols, but further studies will be needed to compare the effects of different other commercially available products. and formulations.
source : Eurekalert.org