Can I tell exosomes apart from other microvesicles?

Exosomes are smaller (30-120 nm) than other small microvesicles (100-1,000 nm). Density gradient ultracentrifugation and dynamic light scattering analysis provides an accurate way to enrich and analyze exosomes in solution, while excluding other small microvesicles and macromolecules, based on size analysis. Samples can also be directly analyzed by electron microscopy however, this requires extensive sample preparation and fixation of the samples. While there are no markers that exclusively stain exosomes, there are common markers that should be present on your exosomes (CD-63, CD-81, CD-9, HSP70, HSP90, MHC Class II), but will not necessarily be found on non-exosome microvesicles.