Abstract
The Caco-2 cell line is derived from a human colon adenocarcinoma and is generally used in toxicity assays. The ingestion of soil or dust is a significant route of human exposure to potential harmful elements (PHE), and assays of bioaccessibility or bioavailability can be used to measure the potential hazard posed by exposure to toxic substances. The in vitro digestion (UBM method) and Caco-2 cell model were used to investigate the bioaccessibility and absorption by intestinal cells of the PHE in four matrices (two urban soils and two soils with lead (Pb)—mining tailings) along with the guidance material for bioaccessibility measurements, BGS 102. The gastrointestinal (GI) compartment was simulated, and the resulting material added to Caco-2 cells. In the GI, the average bioaccessibility was 24% for cadmium (Cd), 17% for copper (Cu), 0.2% for Pb, 44% for manganese (Mn) and 6% for zinc (Zn). The poor reproducibility was attributed to the pH (6.3) and the highly complex GI fluid that formed PHE precipitates and complexes. In 2 h, Caco-2 cells absorbed 0.2 ng mg−1 of cellular protein for Cd, 13.4 ng mg−1 for Cu, 5 ng mg−1 for Mn and 31.7 µg mg−1 for Zn. Lead absorption was lower than the limit of quantification (< 2 µg L−1). Cd was presented in the cell monolayer and could interfere in the intracellular accumulation of Cu, Mn and Zn. The use of in vitro assays allowed for an estimation of the absorption of Cd, Cu, Mn and Zn from environmental matrices to be made, and except for Mn, it had a positive correlation with bioaccessible concentration, suggesting a common association of these elements in the cellular environment.
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Acknowledgements
This study was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Grant 2015/19332-9 and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES) - Finance Code 001. We thank Dr Mark Cave (British Geological Survey) for help in statistical analyses. We also thank Dr Carla Patinha (GeoBiotec, University of Aveiro) for support the first author’s laboratory training with oral bioaccessibility assays. Finally, we are grateful to José Eduardo Amaral, Larissa Torres, Flávia Paggiaro and Talita Negri (Luiz de Queiroz College of Agriculture, ESALQ), for their technical support on Caco-2 cells assays. We also thank to Dr Paulo Roberto Araújo Berni, for helpful advices on Caco-2 cell culture.
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Boim, A.G.F., Wragg, J., Canniatti-Brazaca, S.G. et al. Human intestinal Caco-2 cell line in vitro assay to evaluate the absorption of Cd, Cu, Mn and Zn from urban environmental matrices. Environ Geochem Health 42, 601–615 (2020). https://doi.org/10.1007/s10653-019-00394-4
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DOI: https://doi.org/10.1007/s10653-019-00394-4