Isolation and Analysis of Tumor-Derived Exosomes.

A method for isolation of exosomes from tumor cell supernatants or cancer patients' plasma is presented. Tumor-derived exosomes (TEX) are defined as a subset of extracellular vesicles (EVs) sized at 30 to 150 nm and originating from multivesicular bodies (MVBs). The method utilizes size exclusion chromatography (SEC) for recovery of exosomes from cell-line supernatants or cancer patients' plasma. The recovered exosomes are morphologically intact, aggregate-free, and functionally competent. Their molecular content parallels that of the parent tumor cells and they carry various immunoregulatory ligands known to modulate functions of immune cells. All exosomes isolated from tumor cell lines are TEX, while those isolated from plasma of cancer patients have to be fractionated into TEX and non-TEX. Mini-SEC allows for exosome isolation and recovery in quantities sufficient for molecular profiling, functional studies, and, in the case of plasma, further fractionation into TEX and non-TEX. The mini-SEC method can also be used for comparative studies of the exosome content in serial specimens of cancer patients' body fluids.