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Evaluation of air-liquid interface exposure systems for in vitro assessment of airborne pollutants
Citation:
Zavala, J. AND M. Higuchi. Evaluation of air-liquid interface exposure systems for in vitro assessment of airborne pollutants. Genetics and Environmental Mutegenesis Society (GEMS), Research Triangle Park, NC, November 09, 2016.
Impact/Purpose:
This abstract will be presented at the Genetics and Environmental Mutagenesis Society (GEMS) meeting, November 9, 2016, Research Triangle Park, NC
Description:
Exposure of cells to airborne pollutants at the air-liquid interface (ALI) is a more realistic approach than exposures of submerged cells. The published literature, however, describes irreproducible and/or unrealistic experimental conditions using ALI systems. We have compared five ALI systems for their ability to deliver both particulate matter (PM) and gases to cells cultured on porous membrane inserts. The ALI systems use different mechanisms to deliver pollutants to the inserts: diffusion, sedimentation, electrostatic precipitation (ESP), and thermophoresis (THP). We used fluorescent polystyrene latex spheres (PSLs) as a surrogate for PM to assess the efficacy of particle deposition in each system. PM loading in each insert was determined by dissolving the PSLs in ethyl acetate and measuring the fluorescence. Results show that using ESP as an external force enhances deposition of 50-nm PSLs by 5.5-fold and 11-fold for 1-µm PSLs when compared to diffusion alone. Similarly, THP enhances deposition of 50-nm and 1-µm PSLs by 4.5-fold and 2.7-fold, respectively. The interaction of ozone with an indigo dye on the surface of the insert showed that diffusion alone permitted gas-cell interaction. For each system there were various design and operational factors, such as the flow rate, surface materials and flow path geometry that adversely affected performance. Increased flow rates correlated with increased efficacy of the systems to deliver the gas to the inserts. Our results provide insights as to why inconsistent or unrealistic experimental conditions have been used with similar ALI exposure systems. [Abstract does not reflect the policies of the EPA.]