Fig. 4

Characterization and microRNA expression analysis of human exosomes isolated from the plasma of patient-derived xenograft (PDX) mice. Exosomes were isolated from the plasma of Huntsman Cancer Institute human breast cancer orthotopic xenograft (HCI-PDX) and nod scid gamma (NSG) mice. a Exosomes were characterized by nanoparticle tracking analysis of 500X diluted exosomes (n = 3). b-c Exosomes were isolated from the mouse plasma exosome sample by magnetic-bead based immunoaffinity isolation using an antibody against human CD63, the total RNA was extracted and the expression of miR-1246 and miR-122 were evaluated by qRT-PCR analysis (absolute quantitation) in the immunoaffinity isolated human CD63-positive exosomes from the plasma of three NSG (n = 3, in triplicate) and nine HCI-PDX models (with available biological replicates as indicated in c, in triplicate); Student’s t test; ***p < 0.001. The corresponding clinical biomarkers including the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor 2 (HER2) amplification status and the PAM50 subtype of the human tumor (if known) are indicated and are available in Additional file 2