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A data-driven assessment of the need for harmonization as a path forward for increasing confidence in in vitro air-liquid interface systems for chemical testing
Citation:
McCullough, S. A data-driven assessment of the need for harmonization as a path forward for increasing confidence in in vitro air-liquid interface systems for chemical testing. Society of Toxicology Annual Meeting, San Diego, CA, March 27 - 31, 2022.
Impact/Purpose:
Present information addressing the development and deployment of in vitro new approach methodologies for safety evaluation of inhaled chemicals.
Description:
Air-liquid interface (ALI) cultures afford an invaluable level of biological relevance for examining the effects of chemical exposures in the respiratory tract; however, their use is subject to variability that can confound data interpretation and inhibit their acceptance and use in toxicological testing and research. Commercially available tissues are a valuable resource for inhaled chemical testing, but their use incurs high costs, dependence on tissue providers, and limited transparency of proprietary reagents and construction methods. “Open source” models have the potential to improve accessibility to high-quality in vitro tissues, but their use faces other challenges such as variation in methods and reagents across users. Harmonizing core aspects of the construction, use, and reporting of both commercial and “open source” approaches to the use of in vitro reconstructed ALI tracheobronchial tissues is critical to building confidence in these systems for chemical safety testing. Here, data from our studies examining the pre- and post-exposure variability of these endpoints will be presented to highlight critical considerations facing the wide-spread use of both commercial and open source in vitro reconstructed ALI tracheobronchial tissues. Specifically, this presentation will discuss: 1) differences in exposure-induced pro-inflammatory and oxidative stress gene expression between immortalized and primary bronchial epithelial cells; 2) impacts of common methodological differences on trans-epithelial electrical resistance (TEER) measurements; 3) the effect of donor variability on gene induction, TEER, mucus production, and ciliary beat frequency; 4) the effect of re-submersion of differentiated ALI cultures on global gene expression and biological pathway activation in primary bronchial epithelial cells and co-cultured lung fibroblasts; and 5) incorporation of aspects of the cellular microenvironment (i.e., stromal cells and extracellular matrix proteins) on bronchial epithelial culture physiology and exposure outcomes (culture morphology, exposure-responsive gene expression, TEER, and cytotoxicity). Addressing key biological factors through harmonization of in vitro systems and endpoint assays will be critical for the development of confidence in their predictive value and thus for their utility in regulatory decision making. Does not reflect EPA policy