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Regulating temperature and relative humidity in air-liquid interface in vitro systems eliminates cytotoxicity resulting from control air exposures
Citation:
Zavala, J., R. Greenan, Todd Krantz, D. DeMarini, M. Higuchi, Ian Gilmour, AND P. White. Regulating temperature and relative humidity in air-liquid interface in vitro systems eliminates cytotoxicity resulting from control air exposures. Toxicology Research. Royal Society of Chemistry, London, Uk, 6(4):448-459, (2017). https://doi.org/10.1039/c7tx00109f
Impact/Purpose:
The International Agency for Research on Cancer (IARC) has classified both DE and outdoor air pollution as group l (known) human lung carcinogens (TARC, 2013, Loomis et al., 2013). In addition to cancer, a wide variety of other health effects are associated with air pollution, including cardiovascular disease, asthma, chronic obstructive pulmonary disease, low birth weight, upper-respiratory infections in children, and premature mortality (Dockery et al., 1993, Brook , 2008, Stieb et al., 2012, Anderson et al., 2013a, Gan et al., 20 13). Although much is known regarding the mechanisms by which air pollution and its various components cause these diseases, deeper understanding has been hampered by the lack of suitable methods for exposing lung cells in vitro at an air-liquid interface (ALI) that mimic in vivo exposure conditions. A suitable in vitro exposure system would help, for example, assess the relative toxicity of multi-pollutant mixtures containing both particle- and gas-phase components that interact with each other and produce secondary reaction products (Zavala, 2014). The use of in vitro studies for characterizing the relative changes between exposure conditions has become a necessity due to the cost and technical complexity of in vivo methods.
Description:
VITROCELL® systems permit cell exposures at the air-liquid interface (ALI); however, there are inconsistent methodologies in the literature for their operation. Some studies find that exposure to air (vehicle control) induced cytotoxicity relative to incubator controls; others do not mention if any cytotoxicity was encountered. We sought to test whether temperature and relative humidity (temp/RH) influence cytotoxicity with an unmodified (Conditions A & B) and modified (Condition C) VITROCELL® 6 CF with temp/RH controls to permit conditioning of the sampled air flow. We exposed BEAS-2B cells for 1 h to air and measured viability (WST-1 cell proliferation assay) and lactate dehydrogenase (LDH) release 6 h post-exposure. Relative to controls, cells exposed to air at (A) 22°C and 18% RH had a 47.9% ± 3.2% (p 75% RH showed no changes in cell viability and no increase in LDH release. Cells exposed to air at 37°C and >75% RH 24 h post-exposure showed no changes in viability or LDH release relative to incubator controls. Thus, reductions in cell viability were induced under conditions used typically in the literature (Condition A & B). However, our modifications (Condition C) overcome this shortcoming by preventing cell desiccation; regulating temp/RH is essential for conducting adequate ALI exposures.
URLs/Downloads:
DOI: Regulating temperature and relative humidity in air-liquid interface in vitro systems eliminates cytotoxicity resulting from control air exposures