VEGF-C promotes BM EC proliferation and increases the expression of hematopoietic-regenerative factors after irradiation. (A) Experimental setup for evaluating the effects of Vegfc in the BM upon irradiation. Vegfc was deleted from the BM in 10-week-old Rosa26-CreER^T2;Vegfc^flox/flox mice using tamoxifen injections. Vc^iΔR26 and Vc^fl/fl mice received 4-Gy irradiation after a 2-week tamoxifen washout. Niche cells were isolated from irradiated (IR) Vc^iΔR26 and Vc^fl/fl mice and their nonirradiated (N-IR) controls 7 days after irradiation and analyzed using scRNA-seq. (B-C) UMAP plot showing the clustering of integrated nonhematopoietic BM stroma cells from IR Vc^iΔR26 and Vc^fl/fl mice and their N-IR controls. UMAP plot showing nonhematopoietic BM stroma cells from irradiated Vc^iΔR26 and Vc^fl/fl mice and their N-IR controls separately. Note that damaged ECs (green arrowhead) and Aqp1^hi ECs (blue arrowhead) are increased after irradiation. (D) Percentages of the clusters (damaged ECs, Aqp1^hi ECs, and Cxcl10 ECs) and quantification of ECs in S phase. (E) Dot plot showing selected differentially expressed genes in SECs (SEC-1, SEC-2, and Cxcl10 ECs), damaged ECs, Aqp1^hi ECs, and AECs. Analysis of differentially expressed genes was performed between IR;Vc^fl/fl vs N-IR;Vc^fl/fl and IR;Vc^iΔR26 vs N-IR;Vc^iΔR26.