Is there a difference between exosomes recovered by an isolation reagent kit and ultracentrifugation? How do I determine which protocol is "best"?
Ultimately, the “best” method for exosome isolation is the one that works best with your samples, in your laboratory and in your hands. Therefore, there is no one-size-fits-all answer. However, there are some universal truths that may help you to narrow down your options.
Generally speaking, ultracentrifugation is considered to be the gold standard for exosome isolation, while other methods are newer and less widely adopted. Ultracentrifugation is able to selectively isolate bodies within a narrow size window and relies on differences in flotation to minimize the amount of non-exosome co-precipitates of a similar size concentrated in the sample. Isolation reagent kits generally rely on immunophenotype-based enrichment of the exosome sample, which requires antibodies to bind with surface proteins on the exosome. The antibodies are usually bound to beads, which enables the rapid density-based isolation of bead-bound exosomes.