Figure 4.

Successful retargeting of Ad5 to FAP-expressing fibroblasts in vivo

(A) HER2-overexpressing NCI-N87 tumor cells and GFP-labeled, mFAP-expressing NIH3T3mFAP fibroblast cells were co-injected subcutaneously into the flank of SCID/beige mice. After tumor establishment (200 mm³ tumor volume), mice were treated intratumorally with 3 × 10⁹ PFU FAP-retargeted or untargeted Ad5 encoding TdTomato. Three days post injection, tumors were harvested and analyzed by flow cytometry. Transduced cells were detected via TdTomato expression and further characterized by cell surface marker staining or GFP expression. Each data point represents a single mouse. Bars represent mean ± SD of five mice per group. Statistics: unpaired t test; ∗p < 0.05. Representative data of two independent experiments are shown. (B) Quantification of (A), indicating mean values of transduced cells. (C) Immunohistochemical analysis of (A) to investigate the cell specificity of FAP-retargeted Ad5. Representative immunofluorescence images of tumor tissues stained for HER2 (cyan) and counter-stained with DAPI (blue) for nuclei staining. FAP⁺ cells were detected via GFP expression (green), and cells transduced with Ad5 were detected via TdTomato expression (magenta). Scale bars 1 mm.