Exosomes, (50-150 nm sized vesicles), are secreted by all cells and found in all body fluids investigated. Isolation and characterization of exosomes from cell culture systems and body fluids provide valuable information about the biological system. The level of exosomes in human serum will vary depending on many factors such as age, sex, time of sample collection (circadian rhythm/nutrition status) , and of particular interest during diseased conditions. Such information may possibly be used for early detection of disease, monitoring of disease and/or effect of treatment.
The established standard for exosome isolation is differential ultracentrifugation a method which cannot discriminate between exosome subpopulations or other particles with similar size and density.
Here researcher from Oslo University Hospital have established a direct method for specific isolation of exosomes from cell culture supernatant suitable for a range of different downstream applications. Magnetic beads targeting human CD9 or CD81, common exosomal markers, were used to first isolate and characterize pre-enriched exosomes addressing critical factors (volume, time and exosome concentrations) to establish optimal and comparable isolation conditions. Finally, exosomes were isolated and characterized directly from cell culture media.
Analysis of precipitated exosomes.