Utility of Extracellular Vesicles and Their MicroRNA Cargo As Biomarkers for Alzheimer's Disease

AbstractBackgroundAlzheimer’s disease (AD) is the most common cause of dementia. Developing effective therapies is dependent on the availability of biomarkers that accurately diagnosis AD and track disease progression. MiRNAs, which can be sorted into extracellular vesicles (EVs), reflect the disease state of many neurological disorders and have the potential to serve as biomarkers.MethodCerebrospinal fluid (CSF) from AD, Parkinson’s disease (PD), and control (n=10/group) participants was analyzed by vesicle flow cytometry for size, concentration, and subtypes of EVs. In matching CSF and isolated CSF‐EVs we measured the expression of 34 miRNAs (previously validated candidate AD biomarkers) and assessed magnitude of fold change and classification potential for AD.ResultThe EVs in CSF from AD and PD were significantly larger than control CSF and there were fewer microvesicles. CSF‐EVs had 25 detectable miRNAs out of 34 assayed; while 30 were detectable in total CSF. For the detectable miRNAs in CSF‐EVs, 52% had at least a 1.5 fold change in expression in AD, relative to control. In total CSF, 30% of the assayed miRNAs had a 1.5 fold change in AD versus control. Classification performance for AD from controls was improved for CSF‐EV miRNAs, compared to total CSF. Four of the CSF‐EV miRNAs also had an AUC > 0.7 for classifying AD from PD.ConclusionEV biogenesis in neurodegenerative diseases is disrupted compared to neurologically normal controls, which leads to an altered EV profile in CSF. Further, the miRNA expression profile of CSF‐EVs improves the performance of candidate AD biomarkers.