Exosomes were isolated from the plasma of AML patients and from supernatants of leukemia cell lines (Kasumi-1, ThP1, MLL-1) using mini size-exclusion chromatography (mini-SEC) on Sepharose 2B columns as previously described by us [12 (link), 27 (link)]. Plasma was centrifuged at 2000 × g for 10 min at 4 °C and then at 10,000–14,000 × g for 30 min at 4 °C. Clarified plasma was passed through 0.22 μm-pore Millipore filter and used for exosome isolation by SEC performed using 1.5 cm × 12 cm columns (Bio-Rad, Hercules, CA, USA; Econo-Pac columns) packed with Sepharose 2B (Sigma-Aldrich, St. Louis, MO, USA). The column bed volume was 10 mL. Clarified plasma (0.5–1.0 mL) was loaded onto the column and eluted with PBS. 1 ml fractions were collected. Exosomes that eluted, in fraction #4 were harvested and their protein content, size, nanoparticle numbers, morphology, and molecular content were determined as previously described by us [12 (link), 27 (link)]. The protein content in fraction #4 was determined using the Pierce BCA protein assay kit (Pierce Biotechnology, Rockford, IL), and the exosome protein concentration was expressed as μg protein/ml of precleared plasma loaded onto each mini-SEC column.