Shinkichi Ishikawa, Kazushi Matsumura, Nobumasa Kitamura, Kanae Ishimori, Yuichiro Takanami, Shigeaki Ito
Scientific Product Assessment Center, Japan Tobacco Inc., 6-2, Umegaoka, Aoba-Ku, Yokohama, Japan
This Poster shows the exposure of nicotine and TPM in the mainstream aerosols from 3R4F and novel tobacco vapor on MucilAir™ cells using the Vitrocell® exposure system. The results are shown in cytotoxicity, IL-8, IL-1ß and gene expression.
The development of appropriate in vitro test methods can help to minimize the costs and time required for toxicological testing. For these reasons, various in vitro approaches have been developed for the field of inhalation toxicology. A unique characteristic of such models is the ability to directly expose the air–liquid interface of cultured cells to fresh aerosols. The Vitrocell® exposure system is one such system that consists of three steps: the generation of cigarette smoke (CS) by a smoking machine, dilution of the CS by dilution flow, and the introduction of smoke to the specially designed module by exposure flow (Fig. 1A). Furthermore, recent advances in cell culture technology have enabled the reproduction of mucociliary differentiated human bronchial epithelium in vitro from primary cells. The application of an organotypic airway tissue culture to the Vitrocell® exposure system has the potential to reproduce tissue level responses to CS exposure in vitro (Fig. 1B). In this study, we introduced a commercially available human organotypic bronchial epithelial culture MucilAir™ into the Vitrocell® exposure system to develop an in vitro inhalation toxicological model system. We exposed CS from research reference cigarette 3R4F to MucilAir™ and analyzed the effect on cytotoxicity, histology, cytokine secretion and global gene expression. By adjusting the dilution flow and the number of cigarettes smoked, we exposed cells to five different doses of 3R4F smoke to determine the dose-dependent effect on each biological endpoint. The vapor from a novel tobacco vapor (NTV) product, which we recently developed (Yuki et al., 2017; Takahashi et al., 2018), was also exposed to MucilAir™ in the same dilution flow as used for the 3R4F smoke exposure to examine its effect on each endpoint. We also estimated the amount of total particulate matter (TPM) delivered to the cells by measuring the amount of nicotine delivered to the exposure surface of the cell culture insert under each exposure condition. The dosimetry data indicate the exposure dose to the tissue, which correlates directly to the analyzed biological effects.