Dear Simona,

First, we have never attempted to stain internal exosomal cargo components with antibodies.

However, since exosomes are similar in composition to the cell membrane itself, I would give a try to a standard cell fixation and permeabilization protocol. Comparing the hydrodynamic radius of an antibody to the average radius of an exosome, one might suspect that “cargo” specific staining might not be very efficient. But of course that's just a thought...

thanks a lot Sigurd!