The use of in vitro human biomarkers from relevant primary cell lines, to assess the effects of increasing nicotine concentration in e-liquids
As part of the ongoing stewardship of electronic cigarettes, and in line with the National Academies of Sciences “Toxicity Testing in the 21st Century: A Vision and a Strategy”, Fontem Ventures B.V. have investigated the utility of a series of endpoints in human primary cells. In the first instance, base e-liquids were used to determine the suitability of the test system.
DiscoverX Corporation, is a leading supplier of cell-based assays and services for drug discovery and development. The BioMAP® product was chosen, consisting of 12 primary human cell-based systems from multiple tissues. Cells are cultured either alone or as co-cultures and stimulated with a combination of biological proprietary factors (e.g. cytokines, growth factors, mediators, etc.) to recapitulate the multi-component signalling networks associated with disease states. The Diversity PLUS panel consists of 148 biomarker readouts and has been used as a tool for phenotypic drug discovery, competitive analysis and comparison to clinical standards of care.
Initial results of a base e-liquid (BL) containing only 50:50 propylene glycol and vegetable glycerine; BL containing 2.5 % nicotine and BL with a content of 4.5 % nicotine were tested at eight concentrations ranging between 0.031 to 4 % added directly to the cell media. BL with nicotine added to cell media at concentrations above 0.5 % lead to a characteristic fingerprint of biomarkers and showed a good dose response relationship with increasing concentration. This lead to an exaggeration of the fingerprint profile in selected cell panels, above that for the base e-liquid itself. The most sensitive cell panel in all cases was found to be the BT cell line composed of B cell and peripheral blood mono nuclear cells.
The results demonstrate that the use of BioMAP® is a sensitive and powerful tool, capable of detecting the addition of nicotine to e-liquids in a panel of human relevant primary cell lines. The next step is to assess the e-liquid aerosol, following stability trials of aerosol trapped in phosphate buffered saline.