Figure 3.

¹⁸F-TFB uptake of brain tumors is elevated after systemic IL-6-NIS-MSC delivery

Representative images of ¹⁸F-TFB-PET imaging (horizontal planes; SUV_bw = 1.6) are shown 1 h after tracer injection of GBM-bearing mice after (A) single IL-6-NIS-MSC injection (n = 5), (B) two IL-6-NIS-MSC injections (n = 5), after (C) WT-MSC injection (n = 3), which served as a control, and (D) no MSC injection (n = 1). Brain area is encircled in red dotted lines and tumor is marked with a white arrow. (E) Tumoral radionuclide accumulation showed significantly higher levels after IL-6-NIS-MSC delivery as compared with WT-MSC control mice 1 h post ¹⁸F-TFB injection. (F–I) Exemplary images of co-registration of anatomical MRI and PET imaging of the brain of the same mice as demonstrated in (A)–(D) showing tumor-selective tracer accumulation. A strong tumoral ¹⁸F-TFB accumulation is revealed after systemic IL-6-targeted MSC-mediated NIS gene transfer (F–G), while tumors after WT-MSC injection did not show levels above background level (H) as well as compared with non-treated tumor (I). Tumors are encircled in yellow dotted lines. Results are expressed as % of the injected dose per mL (volume assessed by MRI) and mean ± SEM is given (two-tailed Student’s t test at each time point; ∗p < 0.05). sg = salivary glands.