Fig. 5
In vivo target engagement of four nanobody constructs after iv injection. A–F In situ labeling of biotinylated M1R56H, P96H, Y102H-13A7-13A7-Nb80 injected iv into wild-type mice at 600 nmol/kg body weight at 30 min showing largely labelling in structures with morphologies consistent with capillaries, and at 1, 2, 4, 8 and 16 h showing cellular labeling in hippocampus. G Positive control: ex vivo staining of naïve mouse brain slice with 50 nM biotinylated M1R56H, P96H, Y102H-13A7-13A7-Nb80. H Negative control: no in situ labeling after intravenous injection of 600 nmol/kg M1AA-13A7-13A7-Nb80 which does not bind mTfR. I Negative control: trace in situ labeling of structures with morphologies consistent with capillaries after intravenous injection of 600 nmol/kg M1R56H, P96H, Y102H-Nb3-Nb3-Nb80. Nb3 has no known targets in wild-type mouse brain