Multiple endpoint in vitro toxicity assessment of a prototype heated tobacco product indicates substantially reduced effects compared to those of combustible cigarette. (February 2023)

• Record Type: Journal Article
• Authors: Chapman, Fiona; Sticken, Edgar Trelles; Wieczorek, Roman; Pour, Sarah Jean; Dethloff, Ole; Budde, Jessica; Rudd, Kathryn; Mason, Elizabeth; Czekala, Lukasz; Yu, Fan; Simms, Liam; Nahde, Thomas; O'Connell, Grant; Stevenson, Matthew
• Is Part Of: Toxicology in vitro. Volume 86(2023)
• Publication Date: 2023-02
• Subjects: Heated tobacco -- Cigarette -- Aerosol chemistry -- Genotoxicity -- Mutagenicity -- High content screening; ALI Air-liquid interface -- bPBS (Smoke/ aerosol) bubbled phosphate buffered saline -- ECMN3 Concentration required to reach three-fold micronucleus induction above background levels -- GSH Glutathione -- GSSG Glutathione disulphide -- HCI Health Canada Intense (smoking regime) -- HCS High content screening -- HPHCs Harmful and potentially harmful constituents -- HTP Heated tobacco product -- LOGEL Lowest observed genotoxic effect level -- MMP Mitochondrial membrane potential -- MN Micronucleus/ micronuclei -- NGP Next generation product -- NNK N-nitrosonornicotine -- NNK Nicotine-derived nitrosamine ketone -- NRU Neutral red uptake (assay) -- p-HTP Prototype heated tobacco product -- PAH Polycyclic aromatic hydrocarbon -- RPD Relative population doubling -- RWD Relative wound density -- RWD50 Time taken for the initial wound to close to 50% of its original area -- SAEIVS Smoke aerosol exposure in vitro system -- THR Tobacco harm reduction -- TPM Total particulate matter -- TSNAs Tobacco specific nitrosamines; Toxicity testing -- In vitro -- Periodicals; Toxicology -- Periodicals; 615.9
• DOI: 10.1016/j.tiv.2022.105510
• Languages: English
• ISSNs: 0887-2333

Abstract

Abstract: This study aimed to compare the aerosol chemistry and in vitro toxicological profiles of two prototype Heated Tobacco Product (p-HTP) variants to the 1R6F Reference Cigarette. In the neutral red uptake screen the p-HTPs were 37–39-fold less potent than 1R6F, in the micronucleus assay, responses to the p-HTPs were 8–22-fold less, and in the Ames test mutagenicity was weak or removed compared to 1R6F. The cardiovascular scratch wound assay revealed 58-fold greater wound healing impairment following exposure to 1R6F smoke extracts than the p-HTPs. Furthermore, in seven cell stress-related high content screening endpoints (cell count, cytochrome c release, mitochondrial membrane potential, GSH depletion, NFkB translocation, phosphorylation of c-jun and phosphorylation of H2AX), at 4 and 24 h, responses were substantially greater to 1R6F smoke extracts at comparable nicotine levels. The reduced in vitro effects of the p-HTPs were attributed to substantial reductions (90–97%) in selected HPHCs measured compared to in 1R6F smoke. The multiple endpoint in vitro assessment approach provides greater mechanistic insight and the first reported toxicological characterisation of these p-HTPs in the literature. Overall, the findings contribute to the growing weight of evidence that HTPs may offer a reduced harm mode of nicotine delivery to adult smokers. Highlights: Prototype heated tobacco product (p-HTP) aerosols and 1R6F cigarette smoke were compared. Substantially reduced levels of harmful and potentially harmful constituents in p-HTP aerosols. Outcomes in five in vitro assays were assessed. Substantially reduced effects observed in vitro following p-HTP aerosol exposure compared to 1R6F. Findings contribute to weight of evidence for HTP tobacco harm reduction potential.