Currently there is no consensus around a general exosome marker. The current recommendation from the research community is therefor to combine detection of many membrane bound or membrane associated proteins in order to verify the presence of membranes. Our own experience is that targets such as the CD63 and CD81 are found in many different exosome preparations – however, for CD9 we detected at least 2 different cell lines releasing exosomes which were CD9 negative (Jurkat cells and several B-cell lymphoma cells, Oksvold et al 2014). Equally important is to document the absence of contaminating vesicles by staining for markers known to be expressed in compartments such as ER, Golgi or nucleus.
It is also important to characterize the host cell in terms of the same markers. From our own work and also others, the expression level in the host cells will vary a great deal depending on the type...which is the case for CD63 as well. So I can only recommend to test this.
for the testing I would strongly recommend to use the following WB detection Abs:
Exosome – anti-Human CD9 (for Western), Cat No. 10626D
Exosome – anti-Human CD81 (for Western), Cat No. 10630D
Exosome – anti-Human CD63 (for Western), Cat No. 10628D
These Abs have been through heavy testing for a very long period of time so we know they work well both on cell lysate and exosome lysate