Alternatives to Animal Testing

This assay evaluates the impact of product samples on human endothelial cells (the single layer-thick cells that line all human blood vessels) that are essential for healthy cardio-vascular function. In this assay a scratch is made in the cell layer and the time taken for the normal cell response of filling – or ‘healing’ – the ensuing gap is measured. Cigarette smoke has been shown to delay wound healing, inhibiting endothelial cell normal migratory behaviour.

In marked contrast, our research shows exposure e-vapour aerosol has no notable inhibiting impact and was near identical to the control conditions – even at the highest concentrations – under the test conditions. Likewise, diluted heated tobacco aerosol similarly showed significantly lower inhibiting impact to endothelial cells when compared to those exposed in cigarette smoke.

CTAs can detect potential carcinogens (substances capable of causing cancer). These complex assays look at certain traits observed in cancer cells, such as assessing cells’ ability to detach from their container (normal behaviour), or remove contact inhibition (cells keep multiplying when they would normally stop growing when they reach the edge of the container they are in).

Our research using this method shows combustible cigarettes exhibited a tumour promotion response. In stark comparison, NGPs demonstrated drastically reduced bioactivity in terms of cellular promotion, with no statistically significant increase in tumour promotion response following exposure to heated tobacco and blu aerosols.”

This suite of stem-cell based assays provides insight into the mechanisms by which chemicals can interact with cells, using mechanisms that potentially cause DNA damage compared to those such as protein folding that do not interact with DNA. These assays help assess how product samples may impact cellular functioning across various reporter cell lines, picking up the tell-tale molecular signs of potential harm. These indicators may include oxidative stress, DNA and protein damage, as well as activation of the p53 gene that has a role in cell cycle regulation and tumour suppression.

Our published research using this methodology shows that undiluted vape e-liquids, and their aerosol extracts, exhibited entirely absent or vastly reduced indications of potential DNA damage in cells, compared to smoke from combustible cigarettes. Our 2021 ToxTracker study was the first to publish results using the assay for the assessment of vape e-liquids and aerosols.

3D Lung Model: A 3D organotypic model (characteristic of the bronchiole tissue in humans) is exposed to cigarette smoke/NGP aerosols, and various endpoints measured to observe any effects. Assays include examining mucus production and measuring the beat frequency of cilia – the mobile, hair-like structures that line the larger airways clearing them of mucus and dirt and trapped particles.

We’ve published several studies using 3D lung models, and all provide promising evidence of harm reduction potential of NGPs for lung health compared to combustible cigarettes. Following exposure e-vapour aerosols in our research, there was no recorded decrease in either the number of cilia, or the number of ciliated cells. The observations were in notable contrast to cigarette smoke, which negatively impacted ciliated lung cells at much lower concentrations. When tested in an equivalent assay, diluted heated tobacco aerosol showed marked reductions in cellular damage when compared to the combustible cigarette comparator.

These approaches observe the interaction between different system biology networks, including genomics, transcriptomics, proteomics and metabolomics. By studying the relationship between genes and molecules, these approaches shed light on how molecular interactions influence events such as disease initiation and progression.

Our research using this technique shows vape aerosol elicits significantly less biological response to human lung cells in vitro than the equivalent exposure to combustible cigarette smoke.

This assay combines automated imaging and quantitative data analysis to provide rich systems biology information, detecting cellular events in human cell lines in response to test materials.

In numerous pieces of research using this methodology, we’ve shown that e-vapour e-liquids elicit lower biological activity when compared to cigarette smoke.

These assays assess the potential for substances to interfere with normal pre-natal development using metabolomics.

To asses developmental toxicity potential, and critically if and at what concentration this occurs, we use a human cell model assay looking at both cytotoxicity and the disruption of key metabolites in the cell.

Our research so far suggests NGPs show significantly reduced developmental toxicity potential compared to combusted cigarettes.

Using transcriptional profiles of genomic biomarkers (molecules that indicate normal or abnormal processes that may be a sign of an underlying condition or disease), these techniques can identify the respiratory and skin sensitisation potential of various substances.

In the first ever vape-related application of this method, our published research shows how Genomic Allergen Rapid Detection assays may effectively differentiate and broadly classify e-liquids based on their sensitisation potential. This suggests such methods could, in the future, be applied to e-liquid testing to raise industry standards and improve product quality for adult smokers.

These assays use a selection of human primary cells from different body organs to test the actions of different chemicals on biomarkers in each cell system.

Our research using this method suggests various NGPs, including e-vapour, are likely less toxic than combustible cigarette smoke, that caused toxicity signatures for thrombosis, as well as immune suppression and skin irritation at higher doses. In contrast, none of the NGPs caused any toxicity signatures during the same testing regime.