Fig. 1

Characterization of a lethal WBI model in NUDE mice. a–c NUDE mice were subjected to 15 Gy, 13 Gy, 12 Gy, and 10 Gy lethal doses of WBI. a The survival rate of the mice was evaluated. Each value represents the cumulative data of 3 independent experiments (N = 3, 31 mice in the 15-Gy WBI group, 21 mice in the 13-Gy group WBI, 15 mice in the 12-Gy WBI group, and 23 mice in the 10-Gy WBI group). Mouse survival curves were calculated using the Kaplan-Meier method, and the p value was determined by the log-rank test and Cox model, ^$p ≤ 0.05 and ^$$p ≤ 0.001 compared to the 10-Gy WBI group. b, c Three days after WBI, small intestinal sections were stained with hematoxylin-eosin-safran (HES). Morphometric analysis was performed: b quantitative assessment of the small intestinal crypt viability to determine the percentage of surviving crypts containing 10 or more adjacent chromophilic cells and a lumen, and c villus height (μm). Each value represents the average of 30–100 independent measurements (where the decreasing doses we observed in each section increased the number of measurable crypts and villi) coming from 3 independently repeated experiments (N = 3, 4 to 6 animals per group and experiment). **p ≤ 0.001 compared with the non-irradiated group, ^$$p ≤ 0.001 compared with the 10-Gy WBI group. d Nude mice received 15 Gy or 10 Gy WBI. At 3 days, non-irradiated and irradiated mice were orally gavaged with 75 mg/ml of 4 kDa FITC-labeled dextran, and 5 h later, blood samples were collected. Small intestinal permeability was determined by a plasmatic dosage of 4 kDa FITC-labeled dextran (mg/ml). Each value represents the average value coming from 2 independently repeated experiments (N = 2, 5 to 10 animals per group and experiment). *p ≤ 0.05, **p ≤ 0.001 compared with the non-irradiated group