Figure 4.

Ex vivo analysis of brain tumors and control organs show tumor-specific IL-6 and NIS protein expression

(A, upper and lower panel) IL-6 protein expression was confirmed in GL261 tumors and throughout the tumor stroma (DAB-positive stain is shown in brown). (B) NIS immunofluorescence staining is shown with ×1 magnification to demonstrate tumor mass and the implantation site in the right caudate putamen. Tumor is encircled in yellow dotted lines. (C) No detectable NIS protein expression is observed in non-tumor brain tissue (close-up view: pink window in B). (D, upper and lower panel) Close-up view (indicated by the white window in B) shows NIS-specific immunoreactivity within the tumor stroma, with areas of high and low NIS protein expression, after systemic application of IL-6-NIS-MSCs, while tumors of mice that had received (E, upper and lower panel) WT-MSCs did not show detectable NIS expression. (F–I) No NIS protein expression was detected in control organs such as liver, lung, spleen, and kidney after IL-6-NIS-MSC administration. A representative image is shown in each.