EMBER multidimensional spectral microscopy enables quantitative determination of disease- and cell-specific amyloid strains.

In neurodegenerative diseases, proteins fold into amyloid structures with distinct conformations (strains) that are characteristic of different diseases. However, there is a need to rapidly identify amyloid conformations in situ. Here, we use machine learning on the full information available in fluorescent excitation/emission spectra of amyloid-binding dyes to identify six distinct different conformational strains in vitro, as well as amyloid-ß (Aß) deposits in different transgenic mouse models. Our EMBER (excitation multiplexed bright emission recording) imaging method rapidly identifies conformational differences in Aß and tau deposits from Down syndrome, sporadic and familial Alzheimer's disease human brain slices. EMBER has in situ identified distinct conformational strains of tau inclusions in astrocytes, oligodendrocytes, and neurons from Pick's disease. In future studies, EMBER should enable high-throughput measurements of the fidelity of strain transmission in cellular and animal neurodegenerative diseases models, time course of amyloid strain propagation, and identification of pathogenic versus benign strains.