<scp>3D</scp> imaging of neuronal inclusions and protein aggregates in human neurodegeneration by multiscale x‐ray phase‐contrast tomography

This study leverages x-ray phase-contrast tomography (XPCT) for detailed analysis of neurodegenerative diseases, focusing on the three-dimensional (3D) visualization and quantification of neuropathological features within fixed human postmortem tissue. XPCT with synchrotron radiation offers micrometer and even sub-micron resolution, enabling us to examine intra- and extraneuronal aggregates and inclusions such as Lewy bodies (LBs), granulovacuolar degeneration (GvD), Hirano bodies (HBs), neurofibrillary tangles (NFTs), β-amyloid plaques, and vascular amyloid deposits in three dimensions. In the reconstructions, we identified the highest electron densities in Hirano and LBs, while NFTs exhibited no significant increase in XPCT contrast. Using cutting-edge high-resolution x-ray synchrotron beamlines, we were now able to detect even detect subcellular differences in electron densities found in GvD. Small-scale inhomogeneities of the electron density were also detected in LBs, potentially relating to inclusions of organelles. Additionally, we reveal here a peculiar 3D geometry of HBs and demonstrate the co-occurrence with GvD in the same neuron. These findings underscore the potential of XPCT as a powerful, label-free tool for spatially resolved neuropathological investigations, opening new avenues for the systematic 3D characterization of inclusions and aggregates in neurodegeneration.