Abstract

‍

This study investigates the neurodevelopmental toxicity of rotenone, a mitochondrial Complex I inhibitor, using a 3D human iPSC-derived brain model known as BrainSpheres. By exposing spheroids at various stages of neural differentiation to rotenone, researchers observed dose- and time-dependent impacts on mitochondrial function, reactive oxygen species (ROS) production, and gene expression. Findings showed increased vulnerability during early differentiation, particularly among dopaminergic neurons, supporting the use of BrainSpheres as a model to assess human-specific developmental neurotoxicity (DNT).

‍

Key Learnings
‍

• BrainSpheres exhibit stage-specific sensitivity to rotenone, with early-stage spheroids showing heightened vulnerability.
• Rotenone selectively impairs dopaminergic neurons even at non-cytotoxic concentrations.
• Disruption of mitochondrial function, calcium reabsorption, and PPAR signaling pathways may underlie observed DNT effects.
• Transcriptomic and metabolomic analyses reveal that rotenone exposure alters key neuronal pathways, especially those tied to synaptogenesis and neurodevelopment.
• The model’s reproducibility and relevance to human neurobiology make it suitable for high-impact toxicology and regulatory science applications.

‍

Methods
‍

Researchers generated BrainSpheres from neural progenitor cells derived from human induced pluripotent stem cells (iPSCs). Differentiated over 2, 4, and 8 weeks, BrainSpheres were exposed to varying concentrations of rotenone for up to 48 hours. A suite of assays—including cell viability, ROS, mitochondrial activity (MitoTracker), immunofluorescence, transcriptomics (microarray), and metabolomics (LC-MS)—was conducted to evaluate cellular and molecular responses.

‍

Conclusions
‍

The study demonstrates that rotenone has a pronounced neurotoxic effect on human brain development in vitro, particularly affecting early-stage neurons and dopaminergic populations. BrainSpheres effectively mimic critical aspects of brain development, providing a valuable tool for screening potential neurodevelopmental toxicants. Results highlight the importance of incorporating human-relevant models in toxicology to better understand environmental risk factors and support regulatory alternatives to animal testing.

‍

Reference

Pamies D, Block K, Lau P, et al. Rotenone exerts developmental neurotoxicity in a human brain spheroid model. Toxicol Appl Pharmacol. 2018;354:101–114. doi:10.1016/j.taap.2018.02.003