Fig. 1

Irradiated GBM cell-derived exosomes reduced their phagocytic capacity by inducing the M2 polarization of microglia. A The sketch map showed that GBM and HMC-3 were implanted in the co-culture system. B A phagocytosis assay proved that 2 Gy irradiation significantly decreased the phagocytic capability of HMC3 cells in the U251–HMC3 co-culture system. C A phagocytosis assay proved that 2 Gy irradiation significantly decreased the phagocytic capability of HMC3 cells in the U87–HMC3 co-culture system. D Exosomes from irradiated U251 cells significantly decreased the phagocytic capability of HMC3 cells. E Exosomes from irradiated U87 cells significantly decreased the phagocytic capability of HMC3 cells. F RT-PCR demonstrated that TGFβ, CCL2, IL-1, IL-10, and CD163 expression increased in HMC3 cells that phagocytized exosomes from irradiated GBM cells, whereas TNFα expression decreased. The opposite results were observed in HMC3 cells that phagocytized exosomes from non-irradiated GBM cells. G In 12 pairs of GBM tissues including primary and recurrent GBM, immunohistochemistry demonstrated that the expression of CD163, which is a marker of M2 polarization, significantly increased in recurrent GBM. H Three representative pathological cases