Fig. 6. Immune cell-derived exosomes in cancer inhibition. Cytolytic activity of CAR exosomes in vitro. (a) Flow cytometry analyses of CAR exosomes linked to latex beads (4 mm diameter) or CAR-T cells stained with the indicated primary Abs. The histograms shown in black correspond to the isotype controls of the respective Abs, whereas the red histograms indicate positive fluorescence. (b) Immunoblots for perforin and granzyme B expression in CAR exosomes and CAR-T cells. (c) Killing activity of CAR exosomes in response to tumor cells. (d) Confocal microscopy analysis of MCF-7 EGFR cells (up) and MCF-7 HER2 cells (down) after incubation with NHS-Rhodamine (Rho)-labelled CAR-EXO-CTX for 2 h, CAR exosomes have notable anti tumor activity in vivo. (e) Tumor volumes of MDA-MB-231 (left), HCC827 (middle) and SK-BR-3 (right) tumor xenografts after treatment with the indicated treatment, (f) and (g) tumor volumes of MDA-MB-231 (b) and SK-BR-3 (c) tumor xenografts after treatment with the indicated CAR exosome treatment with or without blocking recombinant antigen, and (h) cancer cell lines or patient-derived tumour tissue fragments established as subcutaneous xenografts (reproduced with permission under Creative Commons CC BY 4.0 license from ref. 74 Copyright@2019 The Authors).