In-tissue structural biology of the brain: A focus on Alzheimer's disease pathology.

The structure of biology spans length scales from meters to Ångstroms - from whole organisms to the atomic positions of macromolecules. Cryo-electron microscopy is well-established for determining the structures of individual macromolecules in isolation, including pathological aggregates from post-mortem donor Alzheimer's disease brain. Recent advances integrating cryo-fluorescence microscopy, sample preparation and cryo-electron tomography are revealing macromolecular structures in the context of cells and anatomically intact tissues. In this chapter, we describe experimental workflows for targeting the in-tissue structure of Alzheimer's disease pathology. We discuss associated practical considerations and limitations of fluorescence labelling, vitrification, sample thinning by cryo-ultramicrotomy and cryo-focused ion-beam scanning electron microscopy (cryoFIB-SEM), cryogenic correlated light and electron microscopy (cryoCLEM), cryo-electron tomography (cryoET) and in-tissue subtomogram averaging (STA). These experimental considerations may be useful and applicable to amyloids, diseases and fundamental structural biology research questions more broadly.