Fig. 5

MSCs migrate to metastatic breast cancer in vivo. a Frozen sections of the lungs from Luc-231 tumor-bearing and tumor-free mice sacrificed 24 h after MCS.AdLuc.LentiR infusion were stained with anti-PD-L1 (red) for lung metastasis, anti-Luc (green) for luciferase expressed by MSCs, and DAPI (blue). White arrows indicate the co-localization of lung metastatic sites and MSCs. Scale bar, 50 μm. b Representative images show the homing capability of different virus-loaded MSCs to tumor sites. MSC.AdLuc.E1A or MSC.AdLuc.LentiR. were intravenously injected into mice hosting MDA-MB-231 in the lung or tumor-free control. Luciferase signal was monitored by bioluminescence imaging using Xenogen imaging system at indicated time. c Quantification of luciferase activity of MSCs in the lungs of MDA-MB-231 tumor-bearing or tumor-free mice at different time after MSCs infusion. Relative Luc activity (RLA) = Log₂ [(luciferase ROI of the mice infused with MSC.AdLuc.E1A or MSC.AdLuc.LentiR.)/(luciferase ROI of control mice infused with PBS)], (n = 3)