Fig. 3
From: Subtyping of circulating exosome-bound amyloid β reflects brain plaque deposition
Preferential association between Aβ aggregates and exosomes. a Schematics of Aβ protein aggregation. We varied the degree of clustering and used filtration approaches to prepare small and big Aβ42 aggregates, respectively. b Characterization of Aβ protein aggregates. (Left) Transmission electron micrographs showed globular morphology of the prepared Aβ42 aggregates. (Right) Dynamic light scattering analysis confirmed the unimodal size distribution of the different-sized preparations. c Schematics of the exosome-Aβ association analysis. Aβ42 aggregates (small vs. big) were immobilized onto the APEX sensors and treated with equal concentrations of exosomes derived from neuronal cells (SH-SY5Y) to determine the association kinetics. All exosome binding data were normalized against respective Aβ42 aggregate surface areas immobilized onto the sensors (see Methods for details). d Real-time sensorgrams of exosome binding kinetics. In comparison to similar-sized bovine serum albumin (BSA) control aggregates (see Supplementary Fig. 10), exosomes associated more strongly with the Aβ42 aggregates. Importantly, as compared to their binding affinity to the smaller Aβ42 aggregates (left), exosomes demonstrated a much stronger affinity to the bigger Aβ42 aggregates (right). Note the difference in scale on the y axis. All binding affinities (KD) were determined from normalized exosome binding data and relative to BSA controls. KD(small) / KD(big) = 5.27. e Differential association of various extracellular vesicles to Aβ42 aggregates. Vesicles were derived from different cell origins, namely neurons, glial cells, endothelial cells, monocytes, erythrocytes, platelets, and epithelial cells, respectively, and used in equal concentrations for the binding analysis. Employing the APEX platform, we first measured the vesicles’ direct binding with the Aβ42-functionalized sensor (direct). Next, for each cell origin, we labeled the bound vesicles for origin-specific marker (cell origin-specific marker) or pan-exosome marker (i.e., CD63, pan-exosome marker), and measured the associated APEX signal amplification. All measurements were made relative to IgG isotype control antibodies, and performed in triplicate. The data are displayed as mean ± s.d. in (e). Source data are provided as a Source Data file
