Figure 4

Kinetic distribution of Adv-Stat3(-)-loaded MSCs in a breast orthotopic tumor model. (A) MSCs labeled with 5 μM Cell Tracker Red. The cells were observed under a fluorescent microscope after 24 hours (upper panel). The corresponding bright field is shown in the lower panel. Scale bar = 15 μm. (B) Labeling efficiencies of MSCs with Cell Tracker Red at the indicated time points as evaluated by FACS were expressed as mean ± SD in three independent experiments. (C) Representative images showing the distribution of Adv-Stat3(-)-loaded MSCs in an orthotopic tumor. 1 × 10⁶ Cell Tracker Red labeled MSCs were infected with 500 MOI Ade-Stat3(-). Six hours later, these cells were intravenously injected into tumor-bearing mice. The mice were sacrificed and frozen sections of tumor prepared and incubated with FITC-labeled adenovirus hexon antibody after 24 (upper panels), 48 (middle panels), and 72 (lower panels) hours. The sections were counterstained with DAPI and observed under a fluorescent microscope. Scale bar = 20 μm. (D) Cell number of MSCs in normal tissue from the mice in panel c at the indicated time points. After incubating frozen sections with FITC-labeled adenovirus hexon antibody, the sections were observed under a fluorescent microscope. The number of MSCs were counted under ×20 HPF in five random fields and expressed as mean ± SD (n = 3).