Deep sequencing of circulating exosomal microRNA allows non-invasive glioblastoma diagnosis

Characterization of serum exosomes isolated in fractions 8–10 by size exclusion chromatography prior to miRNA sequencing. a Size distribution of particles as analyzed by nanoparticle tracking analysis. b Transmission electron microscopy allowed visualization of vesicles with sizes ranging from 60 to 110？nm in diameter, scale bars？=？500？nm (b-1, wide field) and 200？nm (b-2, close-up). c-1 Mass spectrometry-based proteome analysis of size chromatographic elution fractions 8–10 identified all top 10 exosome marker proteins and c-2 showed significant enrichment of proteins characteristic of exosomes and blood microparticles. Proteins identified in fractions 8–10 showed limited, non-significant associations with compartments like the nucleolus, where certain miRNA species are concentrated. d Bioanalyzer trace of RNA extracted from serum exosomes shows the main population of small RNA and no ribosomal RN