Fig. 1.

Generation and characterization of B2M^–UMSCs. a Schematic diagram of the recombinant lentiCRISPRv2 plasmid targeting B2M. b Western blots of B2M expression in UMSCs with B2M-knockout. c Flow cytometric analyses showing that UMSCs and B2M⁻UMSCs were both positive for CD90 and CD105, but negative for CD34 and CD45. d B2M^–UMSCs and UMSCs showed similar morphology under an optical microscope (scale bars, 200 μm). e Positive immunofluorescence staining of HLA-I expression on the surface of UMSCs, but not on the surface of B2M^–UMSCs with and without IFN-γ. f Flow cytometric analysis of HLA-I expression in UMSCs and B2M^–UMSCs with and without IFN-γ (25 ng/mL)