Characterization of extracellular vesicles and miRNA released by cerebral organoids.

Environmental toxicants can contribute to the development of several neurodegenerative diseases. However, the mechanisms behind this pathology are still incompletely understood. Prompt diagnosis of impending neurodegeneration is crucial for early interventions to prevent cognitive decline. Towards this end, accurate biomarkers for early neurodegenerative processes and exposure risk are needed. Extracellular vesicles (EVs) are lipid particles released by cells which contain many bioactive molecules including miRNAs. EVs may serve both as a route of propagating neurotoxic phenotypes and as a source of biomarkers for neurological disease. However, the exact mechanisms though which EVs could spread the deleterious effects of toxicants and the full spectrum of their usage as biomarkers remain unclear. Organoid models have several advantages, including potential for use in high-throughput toxicant testing and applications in personalized medicine and disease models. However, few studies have examined EV release in brain organoids to determine if the EVs could contain useful biomarkers. We employed several technologies to characterize EVs released by human cerebral organoids and their associated miRNAs. We identified that cerebral organoids consistently release EV-associated miRNA in quantities sufficient for robust analysis with NanoString. Further, pathway analyses revealed that terms related to neurodegenerative disease and nervous system signaling are associated with the recovered miRNAs. Together, these data suggest that cerebral organoids have utility as a tool for the discovery of EV-associated miRNAs involved in neurodegenerative disease and neurotoxicity.