I agree that the characterization of rRNA in exosome samples is interesting, but do you think the current study justifies use of this protocol for biomarker applications?

For example, most of the genes selected for qPCR validation show high expression levels in several normal tissue types in BioGPS. Likewise, Figure 7 shows that most genes expressed in both cellular and exosomal MDA-MB-231 samples are also expressed in MDA-MB-436 exosomes. Do you think that it is safe to assume that genes uniquely expressed in MDA-MB-231 exosomes are also uniquely expressed in MDA-MB-231 cellular samples (in comparison to MDA-MB-436 exosomes and cellular samples, respectively)?

Also, do you think there will be differences between cell line exosome extraction and patient exosome extraction (in regards to protocol and/or resulting RNA quantities)?