Fig. 9

Plasmid DNAs could be packaged by stem cells and transported to recipient cells through exosomes. a Plasmid DNAs were labeled with POPO-3 (POPO-pDNA), and observed in donor hMSCs, secreted exosomes and recipient hMSCs. Exosomes were labeled with Dio green fluorescent dye. b Visualization of POPO-pDNA in hMSCs during liposome mediated transfection under fluorescent microscopy at 2, 6, 24, and 48 h. Scale bar: 200 μm. c Exosomes were collected from culture medium after transfection (PO-MSC-BMP2-Exo) and performed flow cytometry to analyze the amount of POPO-pDNA in exosomes. MSC-Exo was analyzed for baseline, and MSC-Exo containing free POPO-3 iodide was used as control (PO-MSC-Exo). Chloroquine was added in culture medium to inhibit lysosome dependent degradation (CQ-MSC-PO-BMP2-Exo). d Quantitative analysis of ratios of exosomes carrying POPO-pDNAs as determined by flow cytometry, n = 3. e PO-MSC-BMP2-Exo were then incubated with recipient hMSCs and observed by confocal microscopy. Exosomes were labelled by Dio (Green) and cell nucleus was stained by DAPI (Blue). Some exosomes carrying plasmid DNAs (exhibited yellow color) were found to accumulate around the nucleus (yellow arrows). Green arrow: exosomes, red arrow: plasmid DNA, yellow arrow: exosomes carrying plasmid DNA. Scale bar: 25 μm. **p < 0.01, ***p < 0.001