Fig. 4. Neutron capture therapy with boron capsule induces tumour regression in mice.

A Dynamic positron emission tomography-computed tomography (PET-CT) 3D projection images of B16F10 tumour-bearing mice at the indicated time points after intratumoural injection of [⁸⁹Zr]boron capsule (n = 3 mice). B Representative TEM images show the excessive cyto-distribution of boron capsule in B16F10 tumour tissue. Nu, nucleus; BC, boron capsule (n = 3 mice). C Dose composition of normal and tumour tissues during neutron irradiation. Dosimetry evaluation of irradiation was based on mean boron concentrations of tumour and normal tissues 24 h post-administration (n = 3 mice). D–G Assays of tumour growth in mice treated with neutron capsule+neutron irradiation. The mice were treated by boron capsule, PEG-B-COF, imiquimod or PBS with (+N) or without neutron irradiation (n = 6 mice). Data shown as mean ± SD. (two-tailed unpaired Student’s t-test, (****P < 0.0001). Treatments began when the tumour volume reached 100  ± 25 mm³. D, F Average tumour volumes in the mice inoculated with B16F10 xenografts (D) and MC38 xenografts (F), respectively. E, G Bodyweight of each group of mice. H Hematoxylin-Eosin (HE) analysis of B16F10 tumour slices at 7 days after the indicated treatment. Remarkable shrinkage of the nuclei is observed in the BNCT treatment groups. I DNA degradation assay in tumours at 1 day after the indicated treatment. Representative confocal images of tumour slices are shown. DNA fragments were assayed with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL, green fluorescence) and the nuclei were stained with DAPI (blue). J Representative immunofluorescence staining images of FITC-conjugated boron capsule in B16F10 tumour-bearing mice. The experiments for H, I and J were repeated three times independently (n  =  3 mice) with similar results. Source data are provided as a Source Data file.