Interference of several classes of environmental chemicals with human neural crest migration

Abstract

Introduction: The neural crest is a multipotent stem cell population that arises at the neural plate border during early fetal development. Neural crest cells (NCCs) migrate to target sites in the periphery, where they differentiate into multiple cell types, including melanocytes, cranial bones and peripheral neurons. Failure of NCC migration can lead to severe disorders, such as Hirschsprung’s disease.Aim: To test whether toxicants interfere with human NCC migration, a high-throughput migration assay was established. This test system was used to screen an 80 compound library of potential developmental toxicants.Methods: NCCs were derived from human embryonic stem cells. The cells were allowed to migrate for 24 h before toxicants were added to the cells. Migration and viability of the cells were then measured after another 24 h by high-content image analysis and a custom-developed software package.Results: The screening library was assembled by the US national toxicology program (NTP) and consisted of different substance classes, e.g. organophosphates, organochlorines, drug-like compounds, pesticides and polycyclic aromatic hydrocarbons (PAHs). Out of the tested potential developmental toxicants, 26 compounds reduced NCC migration at non-cytotoxic concentrations. Hit-confirmation testing confirmed 23 of the compounds as concentration-dependent inhibitors of NCC migration. Among the potential developmental toxicants identified here, there were several organophosphates (e.g. chlorpyriphos) and drug-like compounds as well as polybrominated diphenyl ethers (PBDEs) and organochlorine pesticides (e.g. DDT and dieldrin), while none of the tested PAHs inhibited NCC migration. The negative controls in the screening library, like acetylsalicylic acid, acetaminophen and saccharin, proved to be non-toxic.Conclusion/Outlook: The newly established test system allows screening of potential developmental toxicants in a high throughput manner for interference with human NCC migration. Confirmation in other types of migration assays is ongoing, and selected compounds from amongst the screen hits are undergoing mechanistic evaluation.