Fig. 3

Ex vivo analysis of [18F]FHBG uptake in mice with different sr39tk expression profiles. a–c Representative [18F]FHBG autoradiographs from various organs of (a) Pf4/sr39tk (Pf4-Cre), (b) CD4/sr39tk (CD4-Cre) and (c) Myh6/sr39tk (Myh6-Cre) mice. sr39tk-expressing mice (sr39tk+; genotype: Cre[tg/+],R26[sr39tk/+]) were compared with Cre-negative control mice (sr39tk−; genotype: Cre[+/+],R26[sr39tk/+]); ‘+’ denotes the wild-type allele. Twenty-micrometer cryosections were used except for lymph nodes (b), which were not cut before autoradiography. Autoradiographs of the same organs from sr39tk+ and sr39tk− mice were derived from the same phosphor screen, but they were not normalized between organs or Cre lines. Organs were not cleared from blood before analysis. Similar results were obtained with organs from ≥3 animals of each genotype. d–f Biodistribution analysis of [18F]FHBG uptake into organs isolated from (d) Pf4/sr39tk (Pf4-Cre), (e) CD4/sr39tk (CD4-Cre) and (f) Myh6/sr39tk (Myh6-Cre) mice with (sr39tk+, black symbols) or without (sr39tk−, open symbols) expression of sr39tk. Uptake was normalized to injected tracer dose (ID) and tissue weight, except for bone marrow (BM, d), which was flushed from one tibia and femur per mouse with 1 mL PBS. Data points represent individual animals. Inset for skeletal muscle in d shows uptake between 0 and 0.2 %ID per g tissue and insets for skeletal muscle in e and lung in f show [18F]FHBG uptake between 0 and 0.5 %ID per g tissue. One-way ANOVA was used to compare [18F]FHBG uptake into organs of sr39tk+ and sr39tk− animals (**p < 0.01 and ***p < 0.001, respectively). Organs were not cleared from blood before analysis. BM, bone marrow; SkM, skeletal muscle