Refining In Vitro Toxicity Models: Comparing Baseline Characteristics of Lung Cell Types

There is an ever-evolving need in the field of in vitro toxicology to improve the quality of experimental design, ie, from ill-defined cell cultures to well-characterized cytotoxicological models. This evolution is especially important as environmental health scientists begin to rely more heavily on cell culture models in pulmonary toxicology studies. The research presented in this study analyzes the differences and similarities of cells derived from two different depths of the human lung with varying phenotypes. We compared cell cycle and antioxidant-related mRNA and protein concentrations of primary, transformed, and cancer-derived cell lines from the upper and lower airways. In all, six of the most commonly used cell lines reported in in vitro toxicology research papers were included in this study (ie, PTBE, BEAS-2B, A549, PSAE, Met-5A, and Calu-3). Comparison of cell characteristics was accomplished through molecular biology (q-PCR, ELISA, and flow cytometry) and microscopy (phase and fluorescence) techniques as well as cellular oxidative stress endpoint analyses. After comparing the responses of each cell type using statistical analyses, results confirmed significant differences in background levels of cell cycle regulators, inherent antioxidant capacity, pro-inflammatory status, and differential toxicological responses. The analyzed data improve our understanding of the cell characteristics, and in turn, aids in more accurate interpretation of toxicological results. Our conclusions suggest that in vitro toxicology studies should include a detailed cell characterization component in published papers.