A New Cell Culture Exposure System (CCES) for Studying the Toxicity of Volatile Chemicals at the Air-Liquid Interface
Citation:
Zavala-Mendez, J., A. Ledbetter, D. Morgan, L. Dailey, E. Puckett, S. McCullough, AND M. Higuchi. A New Cell Culture Exposure System (CCES) for Studying the Toxicity of Volatile Chemicals at the Air-Liquid Interface. INHALATION TOXICOLOGY. Taylor & Francis, Inc., Philadelphia, PA, 30(4):169-177, (2018). https://doi.org/10.1080/08958378.2018.1483983
Impact/Purpose:
A wide range of in vitro and in vivo exposure assessment tools have been employed to experimentally assess the toxicological activity of aerosols, vapors, and gases. Although in vivo inhalation exposure studies permit cause and effect assessments, in order to determine the range required to induce adverse biological responses real time toxicological studies of air pollutants conducted in a laboratory usually necessitate use of elevated exposure concentrations, relative to what is found in the ambient air. In vitro tools offer an attractive alternative, but assessments of airborne contaminants are challenging because cultured cells are often grown in a liquid suspension or adhered to a solid substrate covered with liquid medium.
Description:
A cell culture exposure system (CCES) was developed to expose cells established at an air-liquid interface (ALI) to volatile chemicals. We characterized the CCES by exposing indigo dye-impregnated filter inserts inside culture wells to 125 ppb ozone (O3) for 1 h at flow rates of 5 and 25 mL/min/well; the reaction of O3 with an indigo dye produces a fluorescent product. A 5-fold increase in fluorescence at 25 mL/min/well versus 5 mL/min/well was observed, suggesting higher flows were more effective. We then exposed primary human bronchial lung epithelial cells (HBECs) to 0.3 ppm acrolein for 2 h at 3, 5, and 25 mL/min/well and compared our results against well-established in vitro exposure chambers at the U.S. EPA’s Human Studies Facility (HSF Chambers). We measured transcript changes of heme oxygenase-1 (HMOX1) and interleukin-8 (IL8), as well as lactate dehydrogenase (LDH) release, at 0, 1, and 24 h post-exposure. Comparing responses from HSF Chambers to the CCES, differences were only observed at 1 h post-exposure for HMOX1. Here, the HSF Chamber produced a ~6-fold increase while the CCES at 3 and 5 mL/min/well produced a ~1.7-fold increase. Operating the CCES at 25 mL/min/well produced a ~4.5-fold increase; slightly lower than the HSF Chamber. Our biological results, supported by our comparison against the HSF Chambers, agree with our fluorescence results, suggesting that higher flows through the CCES are more effective at delivering volatile chemicals to cells. This new CCES will be deployed to screen the toxicity of volatile chemicals in EPA’s chemical inventories.
URLs/Downloads:
DOI: A New Cell Culture Exposure System (CCES) for Studying the Toxicity of Volatile Chemicals at the Air-Liquid Interface