Exosomes and microvesicles in general have gained significant attention, both for liquid biopsy applications as well as potential treatments. One limitation to understanding and purifying these sub-cellular particles is the limits of technology to characterise particles of such small size. FACS analysis is a well-established method for quantifying numerous proteins, however the sensitivity of these instruments limits their use to larger objects. Not only does the size of the particles limit accurate analysis, the sensitivity of detection is limited to 1000s of target molecules, far beyond the level that may be expressed in smaller (<50nm) particles.
Employing a bead array approach to the analysis of microvesicles, exosomes in particular, we have overcome these limits and now provide an easy to use kit that allows identification and relative quantification of 37 different surface markers. The flexibility of the kit allows for sorting of specific populations for determination of molecular payloads and substitution of detection reagents to characterise novel markers on mixed populations. Here we present data showing marker expression on exosomes derived from cancer cell cultures, isolated blood cells and urine.
Screening of exosomes isolated from the blood of melanoma patients, we have identified a unique signature compared to healthy controls, an approach that may prove fruitful for non-invasive diagnostics and assessment of treatment. Moreover, varying assay conditions unveils heterogeneity in the surface markers expressed on the exosomes secreted by different cell types. This kit represents an easy to use, affordable solution for researchers in all areas of microvesicle research.