Fig. 4

Phagocytosis and endosomal escape of PMVs. a PMVs were generated from hUCMSCs after incubation with Calcein-AM (green) for 30 min. Fusogenic VSV-G viral membrane glycoprotein was prepared from Ad293 cells after transfection with pLP-VSVG for 48 h. PMVs were incubated with or without VSV-G for 20 min and then added into HepG2 cell culture in 96-wells. Cells were stained with Hoechst (blue) at 24 h, harvested, and examined by confocal microscopy (upper panel, scale bar = 20 μm). An enlarged view of typical endosomal release is shown in the lower panel (scale bar = 10 μm). b Percentage of cells with fluorescence green signal in the cytoplasm (top, indicating endosomal escape of PMVs) and green dot per cell (bottom, number of PMVs being phagocytosed) are shown as mean ± SEM (n = 3 experiments). Student’s t test is performed between cultures with or without the addition of VSV-G. ***P < 0.001; **P < 0.01; *P < 0.05. c PMVs were generated from hUCMSCs after staining with MitoTracker-Green for 30 min. PMVs were incubated with or without VSV-G for 20 min and then added to HepG2 cell culture in 96-wells. Cells were stained with Hoechst (blue) at 24 h, harvested, and examined by confocal microscopy, scale bar = 10 μm