Extracellular vesicle miRNA from cerebrospinal fluid as potential biomarkers for neurodegeneration

Abstract

AbstractBackgroundExtracellular vesicles (EVs) are a diverse group of small membranous particles classified by protein and nucleic acid content, size, method of biogenesis, and cellular origin. The need for predictive biomarkers for neurodegenerative disease is critical for early detection and potential therapeutic intervention. We have previously identified multiple high ranking miRNAs in total cerebrospinal fluid (CSF) in patients with Alzheimer's disease (AD). To investigate whether these miRNAs are released from cells within EVs, we developed a pipeline to isolate and analyze EV miRNA.MethodEVs are isolated by size exclusion chromatography (SEC) from CSF collected from living donors. EV counts and sizes are determined by nanoparticle tracking analysis (NTA). Immunoblots are used to characterize EV composition and assess purity. Transmission electron microscopy (TEM) is used to assess size and EV structural characteristics. EV total RNA is isolated using commercial based methods. Quantitative PCR (qPCR) is performed using TaqMan Low Density Array (TLDA) miRNA cards.ResultThe CSF EV isolation protocol developed here is capable of isolating pure vesicles of the appropriate size and protein composition. Following miRNA qPCR, more than half of the high ranking miRNAs identified in total CSF from AD patients were observed in the isolated EV population.ConclusionThis pipeline is suitable for isolating EVs and assessing miRNA content in lumbar CSF. A large number of miRNAs isolated from EVs appear to correlate well with previously published data from total CSF, indicating a potential role for EV miRNA cargo as biomarkers for neurodegenerative diseases such as AD.