Fig. 2: NRP1 inhibition accelerates BM vascular regeneration in vivo.

Representative confocal images of VE-cadherin⁺ (magenta) and CD31⁺ (green) BM vessels, and nuclei (blue) in femurs from a non-IRR mice and at b day +3 and day +7 following 500 cGy and treatment with IgG (10 µg/dose) or anti-NRP1 (10 µg/dose). Left image shows full view taken using 20× lens and right images display individual channels from magnified yellow box. Scale bar 50 µm; magnified view scale bar, 20 µm. c Quantification of VE-Cadherin vascular area from the images in a, b. Dotted line represents mean Non-IRR vascular area. Data presented as mean values +/− SEM. (n = 2 independent experiments, d3 IgG n = 4 fields of view, d3 anti-NRP1 n = 5 fields, d7 IgG n = 7 fields, d7 anti-NRP1 n = 7 fields; IgG d3: p = 0.016, anti-NRP1 d3: p = 0.0467, IgG d7: p = 0.0349, anti-NRP1 d7: p = 0.9694. d BM cell counts at day +7 following 500 cGy and treatment with IgG or anti-NRP1 (n = 5 mice/group, p = 0.0025). Dotted line shows cell counts of non-IRR BM. e At left, representative flow cytometric analysis of CD45⁻VE-cad⁺ BM ECs within BM lin⁻ cells from the groups shown. At right, percentages of BM ECs at day +7 following 500 cGy. Dotted line represents %VE-cad⁺ ECs in non-IRR controls (n = 5 mice/group). f At left, representative histograms of % activated caspase 3/7⁺ cells within lin⁻CD45⁻VE-cad⁺ BM ECs at day +7 following 500 cGy. At right, mean % activated caspase 3/7⁺ BM ECs at day +7 following 500 cGy (n = 5/group). Dotted line represents % activated caspase 3/7⁺ ECs in non-IRR controls. g Levels of Evans Blue Dye (EBD) in the BM extracellular space at +24 h following 500 cGy and treatment with IgG or anti-NRP1 (n = 5–6 mice/group, non-IRR vs. IgG: p = 0.0024, IgG vs. anti-NRP1: p = 0.188, non-IRR vs. anti-NRP1 p = 0.2679). d–f Data assessed by Student’s two-tailed t-test, g One-way ANOVA with Holm-Sidak’s multiple comparison two-sided t-test, c Two-sided one-sample t-test and Wilcoxon test used to compare sample means to the mean of non-IRR samples, *p < 0.05, **p < 0.01, ****p < 0.0001. Source data provided as a Source Data file.