title: STED imaging of tau filaments in Alzheimer's disease cortical grey matter.
abstract: Alzheimer's disease (AD) involves the propagation of filaments of tau protein throughout the cerebral cortex. Imaging tau filaments and oligomers in human brain at high resolution would help contribute insight into the mechanism and progression of tauopathic diseases. STED microscopy is a nano-scale imaging technique and we aimed to test the abilities of this method for resolving tau structures within human brain. Using autopsied 50μm AD brain sections, we demonstrate that STED microscopy can resolve immunolabelled tau filaments at 77nm resolution. Ribbon-like tau filaments imaged by STED appeared smooth along their axis with limited axial undulations. STED also resolved 70-80nm wide tau puncta. Of the fluorophores tested, STAR635p was optimal for STED imaging in this tissue. This was in part due to brain tissue autofluorescence within the lower wavelength ranges (488-590nm). Further, the stability and minimal photobleaching of STAR635p allowed STED z-stacks of neurons packed with tau filaments (neurofibrillary tangles) to be collated. There was no loss of x-y image resolution of individual tau filaments through the 20μm z-stack. This demonstrates that STED can contribute to nano-scale analysis and characterisation of pathologies within banked human autopsied brain tissue. Resolving tau structures at this level of resolution provides promising avenues for understanding mechanisms of pathology propagation in the different tauopathies as well as illuminating what contributes to disease heterogeneity.
authors.affiliation: Biomedical Imaging Facility, The University of New South Wales, Sydney, Australia; Imaging Methods Core Facility, BIOCEV, Faculty of Science, Charles University Prague, Czech Republic.
authors.forename: Aleš
authors.initials: A
authors.lastname: Benda
authors.affiliation: Discipline of Anatomy and Histology, School of Medical Sciences, The University of Sydney, Australia.
authors.forename: Hayden
authors.initials: H
authors.lastname: Aitken
authors.affiliation: Discipline of Anatomy and Histology, School of Medical Sciences, The University of Sydney, Australia.
authors.forename: Danielle S
authors.initials: DS
authors.lastname: Davies
authors.affiliation: Biomedical Imaging Facility, The University of New South Wales, Sydney, Australia. Electronic address: r.whan@unsw.edu.au.
authors.forename: Renee
authors.initials: R
authors.lastname: Whan
authors.affiliation: Discipline of Anatomy and Histology, School of Medical Sciences, The University of Sydney, Australia. Electronic address: claire.goldsbury@sydney.edu.au.
authors.forename: Claire
authors.initials: C
authors.lastname: Goldsbury
mesh_terms: D000544:Alzheimer Disease / Q000000981:diagnostic imaging* / Q000473:pathology; D066128:Gray Matter / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D016874:Neurofibrillary Tangles / Q000473:pathology / Q000648:ultrastructure; D061848:Optical Imaging; D013194:Staining and Labeling; D016875:tau Proteins / Q000737:chemistry* / Q000648:ultrastructure
chemical_list: C054369:MAPT protein, human; D016875:tau Proteins
keywords: AD; Alzheimer’s disease; Human tissue; PHF; STED; Super resolution; Tau filament; Tau protein