Fig. 5: EC-specific deletion of Nrp1 accelerates BM vascular and hematopoietic regeneration.

a qRT-PCR analysis for Nrp1 expression in VE-cadherin⁺ BM ECs from Nrp1^fl/fl mice and Cdh5-Cre-ERT2;Nrp1^fl/fl mice following tamoxifen treatment (n = 4–5 mice/group, p < 0.0001). Nrp1 expression was normalized to Gapdh levels and then replicates were normalized relative to the Nrp1^fl/fl group. b Representative microscopic images of VE-cad⁺ BM vessels (red) in femur sections from Nrp1^fl/fl mice and Cdh5-Cre-ERT2;Nrp1^fl/fl mice at day +7 following 500 cGy TBI. Scale bar, 100 µm. c BM cell counts in Nrp1^fl/fl mice and Cdh5-Cre-ERT2;Nrp1^fl/fl mice at day +10 following 500 cGy (n = 10 mice/group; p = 0.001). d Representative flow cytometric analysis of CD45⁻CD31⁺ BM ECs within BM lin⁻ cells from Nrp1^fl/fl mice and Cdh5-Cre-ERT2;Nrp1^fl/fl mice are shown at day +10. At right, representative percentages of Annexin⁺7AAD⁻ and Annexin⁺7AAD⁺ cells within the BM EC population are shown. e At left, mean percentages of CD31⁺ BM ECs within the BM lin⁻ population at day +10 and at right, numbers of femoral CD31⁺ BM ECs at day +10 following 500 cGy TBI (n = 5 mice/group; %BM ECs: p < 0.0001; number BM ECs: p = 0.0056). f Mean percentages of live, apoptotic, and necrotic BM ECs at day +10 following 500 cGy in the groups shown (n = 5 mice/group; p < 0.0001). g PB WBC, NEU, and LYMPHS at day +10 following 500 cGy TBI in Nrp1^fl/fl mice and Cdh5-Cre-ERT2;Nrp1^fl/fl mice (n = 10 mice/group; WBC: p < 0.0001; NEU: p = 0.0014; LYMPH: p = 0.0327). h At left, representative flow cytometric analysis of BM c-kit⁺sca1⁻lin⁻ progenitors and KSL stem/progenitor cells at day +10 following 500 cGy TBI. At right, number of c-kit⁺sca1⁻lin⁻ progenitors and KSL cells at day +10 in the groups shown (n = 10 mice/group, p < 0.0001). i CFC quantification from 10,000 BM cells isolated from mice at day +10 following IR (n = 10 replicates, data are presented as mean values +/− SEM, p < 0.0001). a, c, e, h Student’s unpaired two-sided t-test, f, g, i Two-way ANOVA with Holm-Sidak’s multiple comparison two-sided t-tests. *p < 0.05, **p < 0.01, ****p < 0.0001. Source data are provided as a Source Data file.