In vitro acute and developmental neurotoxicity screening: an overview of cellular platforms and high-throughput technical possibilities

Abstract

Neurotoxicity and developmental neurotoxicity are important issues of chemical hazard assessment. Since the interpretation of animal data and their extrapolation to man is challenging, and the amount of substances with information gaps exceeds present animal testing capacities, there is a big demand for in vitro tests to provide initial information and to prioritize for further evaluation. During the last decade, many in vitro tests emerged. These are based on animal cells, human tumour cell lines, primary cells, immortalized cell lines, embryonic stem cells, or induced pluripotent stem cells. They differ in their read-outs and range from simple viability assays to complex functional endpoints such as neural crest cell migration. Monitoring of toxicological effects on differentiation often requires multiomics approaches, while the acute disturbance of neuronal functions may be analysed by assessing electrophysiological features. Extrapolation from in vitro data to humans requires a deep understanding of the test system biology, of the endpoints used, and of the applicability domains of the tests. Moreover, it is important that these be combined in the right way to assess toxicity. Therefore, knowledge on the advantages and disadvantages of all cellular platforms, endpoints, and analytical methods is essential when establishing in vitro test systems for different aspects of neurotoxicity. The elements of a test, and their evaluation, are discussed here in the context of comprehensive prediction of potential hazardous effects of a compound. We summarize the main cellular characteristics underlying neurotoxicity, present an overview of cellular platforms and read-out combinations assessing distinct parts of acute and developmental neurotoxicology, and highlight especially the use of stem cell-based test systems to close gaps in the available battery of tests.

New experimental models of the blood-brain barrier for CNS drug discovery

“…Both, pluripotent and adult stem cells exhibit significant self-renewal capacity and can acquire any specialized cell genotype/phenotype under cue-directed differentiation for high throughput in vitro disease modeling and toxicity testing [105, 106, 107, 108, 109]. The inherent potential of human induced (iPSC) or embryonic (ESC) pluripotent and progenitor stem cells have been exploited to develop highly functional and physiologically relevant in vitro human BBB models [84, 110, 111].…”

A human brain microphysiological system derived from induced pluripotent stem cells to study neurological diseases and toxicity

“…There is a lack of mechanistic understanding of processes related to (developmental) neurotoxicity (Smirnova et al, 2014; Schmidt et al, 2016) and neurological disorders, partly due to limited representative models of humans. Animal-based models have poor predictivity for human health (Hartung, 2013, 2008), and do not always mimic human pathology.…”

Toxicity, recovery, and resilience in a 3D dopaminergic neuronal in vitro model exposed to rotenone

“…Current in vitro models (cancer cell lines, immortalized cell lines, primary cell cultures or stem cells) offer the advantage of a controlled environment to study molecular pathways involved in neurotoxicity (Hogberg et al 2013; Falkenburger et al 2016). Understanding the limitations of each model is important to determine whether it can answer the question being posed (Schmidt et al 2017). Although iPSC-derived 3D models would be the most representative of the human brain due to their multicellular composition (Pamies et al 2017), their complexity makes it difficult to attribute mechanisms to the respective cell type.…”