Toward a Better Testing Paradigm for Developmental Neurotoxicity: OECD Efforts and Regulatory Considerations

Sachana, Magdalini; Shafer, Timothy J.; Terron, Andrea

doi:10.3390/biology10020086

Cited by 37 publications

(20 citation statements)

References 43 publications

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“…However, there is a paucity of data on DNT. Of the 350,000 chemicals in use globally (Wang et al, 2020), DNT data is only available for approximately 110-140 compounds (Sachana et al, 2021). Current data requirements for in vivo DNT testing are considered insufficient to adequately screen and characterize compounds potentially hazardous for the human developing brain (Bal-Price et al, 2015a).…”

Section: Discussionmentioning

confidence: 99%

Motor dysfunction in Drosophila melanogaster as a biomarker for developmental neurotoxicity

Cabrita

Pereira

et al. 2021

Preprint

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Humans interact with numerous chemical compounds with direct health implications, with several able to induce developmental neurotoxicity (DNT), which bear developmental, behavioral, and cognitive consequences from a young age. Current guidelines for DNT testing are notably costly, time consuming, and unsuitable for testing large numbers of chemicals. Therefore, there is a need for adequate alternatives to conventional animal testing for neurotoxicity and DNT. Here we show that detailed kinematic analysis can provide a strong indicator for DNT, using known (chlorpyrifos, CPS) or putative (β-N-methylamino-L-alanine, BMAA) neurotoxic compounds. We exposed Drosophila melanogaster to these compounds during development and evaluated for common general toxicity — notably developmental survival and pupal positioning, together with the FlyWalker system, a detailed adult kinematics evaluation method.At concentrations that do not induce general toxicity, the solvent DMSO had a significant effect on kinematic parameters. Nonetheless, CPS not only induced developmental lethality but also significantly impaired coordination in comparison to DMSO, altering 16 motor parameters, validating the usefulness of our kinematic approach.Interestingly, BMAA, although not lethal during development, induced a dose-dependent motor decay, targeting most parameters in young adult animals, phenotypically resembling normally aged, non-exposed flies. This effect was subsequently attenuated during ageing, indicating an adaptive response. Furthermore, BMAA induced an abnormal terminal differentiation of leg motor neurons, without inducing degeneration, underpinning the observed altered mobility phenotype. Overall, our results support our kinematic approach as a novel, highly sensitive and reliable tool to assess potential DNT of chemical compounds.

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Section: Discussionmentioning

confidence: 99%

Motor dysfunction in Drosophila melanogaster as a biomarker for developmental neurotoxicity

Cabrita

Pereira

et al. 2021

Preprint

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“…While these systems offer an important approach to address issues of neurotoxicity, they are not devoid of limitations that require attention if these systems are to be put forth as a stand-alone approach to evaluate potential for human neurotoxicity. The applicability of these systems to address questions related to neurotoxicity and developmental neurotoxicity screening has been reviewed in recent articles ( Rosca et al, 2020 ; Sachana et al, 2021 ) as have limitations ( US EPA, 1994a ). Given the focus of the current special issue it is anticipated that many of these model systems proposed for neurotoxicity assessment will be discussed in methodological detail in other articles.…”

Section: In Vitro Model Systems In Neurotoxicity Assessmentmentioning

confidence: 99%

“…These include various in vitro model systems primarily focused on neuronal cells and non-mammalian model systems such as, zebrafish and C. elegans . Many of these model systems are likely covered in accompanying manuscripts in this special issue and have been extensively presented in multiple recent publications ( Schmidt et al, 2017 ; Pistollato et al, 2020 ; Pistollato et al, 2021 ; Sachana et al, 2021 ). However, with this transition comes the need to formulate specific experiments to demonstrate validity of the assays to represent, in vivo , the proposed underlying biological process.…”

Section: Introductionmentioning

confidence: 99%

Roadbumps at the Crossroads of Integrating Behavioral and In Vitro Approaches for Neurotoxicity Assessment

Harry¹,

McBride²,

Witchey³

et al. 2022

Front. Toxicol.

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With the appreciation that behavior represents the integration and complexity of the nervous system, neurobehavioral phenotyping and assessment has seen a renaissance over the last couple of decades, resulting in a robust database on rodent performance within various testing paradigms, possible associations with human disorders, and therapeutic interventions. The interchange of data across behavior and other test modalities and multiple model systems has advanced our understanding of fundamental biology and mechanisms associated with normal functions and alterations in the nervous system. While there is a demonstrated value and power of neurobehavioral assessments for examining alterations due to genetic manipulations, maternal factors, early development environment, the applied use of behavior to assess environmental neurotoxicity continues to come under question as to whether behavior represents a sensitive endpoint for assessment. Why is rodent behavior a sensitive tool to the neuroscientist and yet, not when used in pre-clinical or chemical neurotoxicity studies? Applying new paradigms and evidence on the biological basis of behavior to neurobehavioral testing requires expertise and refinement of how such experiments are conducted to minimize variability and maximize information. This review presents relevant issues of methods used to conduct such test, sources of variability, experimental design, data analysis, interpretation, and reporting. It presents beneficial and critical limitations as they translate to the in vivo environment and considers the need to integrate across disciplines for the best value. It proposes that a refinement of behavioral assessments and understanding of subtle pronounced differences will facilitate the integration of data obtained across multiple approaches and to address issues of translation.

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“…There is a vast amount of data on different compound classes including metals, pesticides, and drugs linking compound exposure to adverse neurodevelopmental outcomes in children, like a drop in IQ or memory and attention deficits ( Vorhees et al, 2018 ). Nevertheless, so far only 110–140 chemicals have been evaluated using in vivo DNT guideline studies ( Makris et al, 2009 ; Paparella et al, 2020 ), while for the majority of the human exposome this data is lacking ( Sachana et al, 2021a ). Moreover, the contribution of chemical exposure to human neurodevelopmental diseases like autism spectrum or attention deficit hyperactivity disorder has so far only been heavily discussed on an associative basis but not finally mechanistically substantiated ( Grandjean and Landrigan, 2006 ; Abbasi, 2016 ; Bennett et al, 2016 ; Gould et al, 2018 ; Moosa et al, 2018 ; Cheroni et al, 2020 ; Masini et al, 2020 ).…”

Section: Introductionmentioning

confidence: 99%

Scientific Validation of Human Neurosphere Assays for Developmental Neurotoxicity Evaluation

et al. 2022

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There is a call for a paradigm shift in developmental neurotoxicity (DNT) evaluation, which demands the implementation of faster, more cost-efficient, and human-relevant test systems than current in vivo guideline studies. Under the umbrella of the Organisation for Economic Co-operation and Development (OECD), a guidance document is currently being prepared that instructs on the regulatory use of a DNT in vitro battery (DNT IVB) for fit-for-purpose applications. One crucial issue for OECD application of methods is validation, which for new approach methods (NAMs) requires novel approaches. Here, mechanistic information previously identified in vivo, as well as reported neurodevelopmental adversities in response to disturbances on the cellular and tissue level, are of central importance. In this study, we scientifically validate the Neurosphere Assay, which is based on human primary neural progenitor cells (hNPCs) and an integral part of the DNT IVB. It assesses neurodevelopmental key events (KEs) like NPC proliferation (NPC1ab), radial glia cell migration (NPC2a), neuronal differentiation (NPC3), neurite outgrowth (NPC4), oligodendrocyte differentiation (NPC5), and thyroid hormone-dependent oligodendrocyte maturation (NPC6). In addition, we extend our work from the hNPCs to human induced pluripotent stem cell-derived NPCs (hiNPCs) for the NPC proliferation (iNPC1ab) and radial glia assays (iNPC2a). The validation process we report for the endpoints studied with the Neurosphere Assays is based on 1) describing the relevance of the respective endpoints for brain development, 2) the confirmation of the cell type-specific morphologies observed in vitro, 3) expressions of cell type-specific markers consistent with those morphologies, 4) appropriate anticipated responses to physiological pertinent signaling stimuli and 5) alterations in specific in vitro endpoints upon challenges with confirmed DNT compounds. With these strong mechanistic underpinnings, we posit that the Neurosphere Assay as an integral part of the DNT in vitro screening battery is well poised for DNT evaluation for regulatory purposes.

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Toward a Better Testing Paradigm for Developmental Neurotoxicity: OECD Efforts and Regulatory Considerations

Cited by 37 publications

References 43 publications

Motor dysfunction in Drosophila melanogaster as a biomarker for developmental neurotoxicity

Motor dysfunction in Drosophila melanogaster as a biomarker for developmental neurotoxicity

Roadbumps at the Crossroads of Integrating Behavioral and In Vitro Approaches for Neurotoxicity Assessment

Scientific Validation of Human Neurosphere Assays for Developmental Neurotoxicity Evaluation

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