Changes in the Morphology, Number, and Pathological Protein Levels of Plasma Exosomes May Help Diagnose Alzheimer's Disease.

Exosomes are nano-sized extracellular vesicles that are secreted by cells and usually found in body fluids. Since they freely cross the blood-brain barrier, neuronal exosomes respond directly to changes in the brain's environment. Recent studies have shown that exosomes contain both amyloid-β (Aβ) and tau proteins and have a controversial role in the Alzheimer's disease (AD) process. In this study, enzyme-linked immunosorbent assay was used to detect the levels of P-S396-tau and Aβ1-42 in plasma exosomes. We found that levels of P-S396-tau and Aβ1-42 in plasma exosomes of AD patients were significantly higher compared to those in matched healthy controls. The difference between plasma exosomes of AD patients and those of matched healthy controls was determined using transmission electron microscopy and nanoparticle tracking analysis. Exosomes from AD patients were smaller and lower in quantity. These data together may provide a basis for early diagnosis of AD.