A Pilot Study of Urinary Exosomes in Alzheimer’s Disease

Background: Exosomes are nano-sized extracellular vesicles secreted by most cell types and abundantly present in body fluids, including blood, saliva, urine, cerebrospinal fluid, and breast milk. Exosomes can spread toxic amyloid-beta (Aβ) and hyperphosphorylated tau between cells, contributing to neuronal loss in Alzheimer’s disease (AD). Objective: To explore changes in the morphology, number, and pathological protein levels of urinary exosomes in AD patients compared with age-matched healthy subjects. Methods: In this study, enzyme-linked immunosorbent assay was used to detect the levels of Aβ1–42 and P-S396-tau (normalized by CD63) in urinary exosomes of AD patients and matched healthy subjects. We used transmission electron microscopy and nanoparticle tracking analysis to observe the exosomes. Results: We found that the levels of Aβ1–42 and P-S396-tau in the urinary exosomes of AD patients were higher than those of matched healthy controls. Exosomes taken from AD patients were more numerous. Conclusion: The differences in levels of Aβ1–42 and P-S396-tau and the quantity of urinary exosomes between AD patients and healthy controls may provide a basis for early diagnosis of AD.