Cigarette smoking is a risk factor for many diseases including cardiovascular disease, lung disease, and cancer. Recently there has been an increase in the development and consumer acceptance of novel nicotine and tobacco products including tobacco-heating products (THPs) and vapour products such as e-cigarettes.

Using a panel of in vitro test methods, recently outlined as part of a framework to substantiate the risk reduction potential of novel tobacco and nicotine products, we have assessed the biological effects of two commercially available THPs, designed to reduce toxicant exposures. Responses were compared to a 3R4F reference cigarette.

Exposure matrices assessed included total particulate matter (TPM), whole aerosol (WA), and aqueous aerosol extracts (AqE) obtained after machine-puffing using the Health Canada Intense smoking regime. Endpoints assessed included cytotoxicity (neutral red uptake viability assay), oxidative stress (antioxidant response element (ARE) activation in lung epithelial reporter cells) and endothelial cell migration (wound healing). In addition, we used a high content screening (HCS) approach to assess ten different toxicity endpoints in primary human bronchial epithelial cells (HBEC).

THPs had little or no activity across all the in vitro assays when compared to the 3R4F reference product. WA from THPs induced cytotoxicity in H292 cells, but only at much higher doses than 3R4F WA. Similarly, the response to TPM treatment in the ARE assay and HCS was significantly lower for THPs than for 3R4F, at both 4 hour and 24 hours. AqE from TPM did not significantly inhibit endothelial wound healing, while 3R4F AqE exhibited a concentration-related response in this assay.

Together, these in vitro assays have enabled the biological assessment of THPs, and results suggest the products demonstrate reduced health risks. Further pre-clinical and clinical assessments are required to understand further the risk reduction of these novel products at individual and population levels.