Ultrastructural Analysis of α-Synuclein Propagation and Pathology in Human Brain Organoids by Electron Microscopy

초록

Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by the degeneration of dopaminergic neurons and the pathological accumulation of α-synuclein (α-syn) aggregates, which form Lewy bodies. To gain deeper insight into the ultrastructural features and cellular effects of α-syn aggregation, we used a midbrain-striatum assembloid model that recapitulates key aspects of PD pathology in a three-dimensional, human-relevant context. To investigate the structural and functional connectivity within the assembloid model, we used large-area correlative light and electron microscopy (CLEM) combined with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to visualise α-syn aggregates with high spatial precision. CLEM combines the wide-field capabilities of light microscopy with the high-resolution power of electron microscopy, enabling precise analysis of α-syn aggregation patterns, their intracellular localization, and their impact on organelle integrity and neural network connectivity. Our results reveal that α-syn aggregates are frequently associated with organelle damage and impaired neural connectivity, suggesting their direct involvement in the neurodegenerative process. These findings underscore the power of SEM-TEM–based CLEM in elucidating the structural dynamics of PD pathology and highlight its potential for identifying novel therapeutic targets.