In vitro micronucleus assay for cigarette smoke using a whole smoke exposure system
Previous studies on the biological assessment of cigarette smoke mainly, focused on the total particulate matter (TPM) collected with a Cambridge filter or gas vapor phase (GVP) bubbled through phosphate buffered saline (PBS). However, these extracted fractions of cigarette smoke may not completely reflect the biological effects of the actual aerosol. To research the effects of native cigarette smoke in vitro, direct exposure methods have been developed recently. Meanwhile, in vitro micronucleus (MN) assays have been reported to evaluate the mutagenicity of cigarette smoke. The objective of this research was to investigate the MN-inducing activity of whole smoke (WS) and GVP casing a whole smoke exposure system, CULTEX®, which allows direct exposure of cultured cells to native cigarette smoke. Smoke was generated according to International Organization for Standardization (ISO; 35ml puff volume, 2 sec duration, once per minute) or Health Canada Intensive (HCI; 55ml puff volume, 2 sec duration, once per 30 sec, with complete blocking for filter ventilation) conditions and exposed to Chinese hamster lung cells (CHL/IU) cultured on microporous membranes. Dosages were adjusted according to the amount of smoke introduced into the exposure position. The unit of the dosage was indicated as the percentage of cigarette smoke (% of cig.). Under both ISO and HCI smoking conditions, WS and GVP from K2R4F reference cigarettes showed doserelated micronucleus responses and dosages which indicated that the highest micronucleus frequency in WS exposure was about one half that of GVP. The CULTEX® system provides insights into biological effects caused by native cigarette smoke in vitro .