High spatial-resolution imaging of label-free in vivo protein aggregates by VISTA

Amyloid aggregation, formed by aberrant proteins, is a pathological hallmark for neurodegenerative diseases, including Alzheimer's disease and Huntington's disease. High-resolution holistic mapping of the fine structures from these aggregates should facilitate our understanding of their pathological roles. Here, we achieved label-free high-resolution imaging of the polyQ and the amyloid-beta (A beta) aggregates in cells and tissues utilizing a sample-expansion stimulated Raman strategy. We further focused on characterizing the A beta plaques in 5XFAD mouse brain tissues. 3D volumetric imaging enabled visualization of the whole plaques, resolving both the fine protein filaments and the surrounding components. Coupling our expanded label-free Raman imaging with machine learning, we obtained specific segmentation of aggregate cores, peripheral filaments together with cell nuclei and blood vessels by pre-trained convolutional neural network models. Combining with 2-channel fluorescence imaging, we achieved a 6-color holistic view of the same sample. This ability for precise and multiplex high-resolution imaging of the protein aggregates and their micro-environment without the requirement of labeling would open new biomedical applications.

Automated summary

Amyloid aggregation, a pathological hallmark in neurodegenerative diseases, was studied using label-free high-resolution imaging and machine learning for specific segmentation of aggregate cores and peripheral filaments. This non-invasive imaging technology allows precise and multiplex high-resolution imaging of protein aggregates and their micro-environment, opening up new biomedical applications.