O'Neil, A. L. | bioRxiv Science

bioRxiv2026

Alzheimer's Disease Brain Organoids as a Source of Disease Relevant Amyloid-Beta Oligomers

Amyloid plaques are a hallmark of Alzheimers disease (AD) progression; however, the early stages of plaque formation and the specific amyloid-beta (A{beta}) species involved remain difficult to study. While post-mortem tissue provides insight into end-stage mature plaques, therapeutic development requires targeting the earliest A{beta} oligomers to arrest plaque formation. Furthermore, inherently toxic soluble A{beta} oligomers off-pathway from plaque formation are implicated as a driving force of AD pathology. It also remains unclear if the specific nature of key disease-relevant species can be accurately replicated in preparations of synthetic peptides.. To bridge this gap, we utilize brain organoids carrying AD mutations as a biologically authentic source for A{beta} peptides and oligomers. We demonstrate that these mutations do not disrupt organoid development and that the resulting conditioned media contains A{beta} oligomers with disease-relevant structures. Finally, we show that these oligomers can be concentrated and segregated via differential ultracentrifugation for further experimental applications.

neuroscience↗

bioRxiv2025

Exposure to the organochlorine pesticide cis-chlordane induces ALS-like mitochondrial perturbations in stem cell-derived motor neurons

Amyotrophic Lateral Sclerosis (ALS) is a debilitating and incurable neurodegenerative disease with unsolved etiology. Due to the large proportion of patients lacking direct disease inheritance, understanding the environmental factors that contribute to ALS development is of high priority. Epidemiological studies have implicated pesticides and other environmental exposures as possible contributors to ALS pathogenesis. Recently, our group determined that the organochlorine pesticide cis-chlordane is toxic to human motor neurons in a dose-dependent manner, causing an ALS-like phenotype in culture and animals with a mode of action independent of its known GABAA antagonism. Here, we aimed to characterize downstream motor neuron phenotypes associated with cis-chlordane treatment. We performed bulk RNA sequencing, live imaging, immunofluorescent labeling, and real-time metabolic assays on stem cell-derived motor neurons to assess chlordane-associated phenotypes in vitro. We demonstrate that cis-chlordane treatment causes a highly altered mitochondrial phenotype in motor neurons, including increased production of reactive oxygen species, decreased OCR and ATP production, and loss of mitochondrial membrane potential. We further implicate cis-chlordane as a possible mediator of potent motor neuron damage, with exposure to the pesticide inducing mitochondrial phenotypes akin to those seen in ALS. We suggest that future studies investigating the role of pesticides in ALS development center upon the organochlorine molecules.

neuroscience↗