Fig. 1

Vascular remodeling of the leukemic BM niche. a CD31 (FITC) and Sca-1 (PE) immunofluorescence (IF) staining (left) and quantification (right) of CD31⁺Sca-1^high EC-lined vessels (i.e., arterioles) in the femurs from normal wt and AML mouse (n = 3 mice per group). b Representative plots (left) and aggregate results (right) of BM EC Sca-1^high and Sca-1^low subfractions from normal wt and AML mouse by flow cytometry analysis (n = 4 mice per group). c CD31 (FITC) and Sca-1 (PE) IF staining (left) and quantification (right) of CD31⁺Sca-1^high EC-lined vessels (i.e., arterioles) in the tibias from wt recipient mice receiving BM mononuclear cells (MNCs) from normal mice (Normal or NL to wt, 1 × 10⁶/mouse, n = 4 mice) or from diseased Mll^PTD/WT/Flt3^ITD/ITD AML mice (AML to wt, 1 × 10⁶/mouse, n = 4 mice). d Representative plots (left) and aggregate results (right) of BM EC Sca-1^high and Sca-1^low subfractions from the same mice as in (c). e Confocal imaging of EC-tdTomato and Sca-1-GFP (left) and quantification (right) of Sca-1-GFP^high EC-lined vessels (i.e., arterioles) in the tibias from tamoxifen-treated Tie2-CreER/TdTomato/Tg(Ly6a-GFP) recipient mice receiving BM MNCs from normal wt mice (Normal or NL to reporter, 1 × 10⁶/mouse, n = 4 mice) or from leukemic Mll^PTD/WT/Flt3^ITD/ITD mice (AML to reporter, 1 × 10⁶/mouse, n = 4 mice). BM engraftment rates were more than 70% when the mice were analyzed. f Representative plots (left) and aggregate results (right) of BM Sca-1-GFP^high and Sca-1-GFP^low subfractions in BM ECs (CD45⁻Ter119⁻tdTomato⁺) from the same mice as in (e). g CD31 (FITC) and Sca-1 (PE) IF staining (left) and quantification (right) of CD31⁺Sca-1^high EC-lined vessels (i.e., arterioles) in the tibias from NSGS mice receiving CB CD34⁺ cells (1 × 10⁵/mouse, n = 3 mice) or receiving human FLT3-ITD+ AML blasts (2 × 10⁶/mouse, n = 3 mice). BM engraftment rates were more than 70% when the mice were analyzed. h Representative plots (left) and aggregate results (right) of BM EC Sca-1^high and Sca-1^low subfractions from the same mice as in (g). For a, c, and g: yellow arrows indicate CD31⁺Sca-1^high EC-lined vessels; white arrows indicate CD31⁺Sca-1^low EC-lined vessels; for e: yellow arrows indicate Sca-1^high EC-lined vessels (i.e., tdTomato⁺GFP^high); white arrows indicate Sca-1^low EC-lined vessels (i.e., tdTomato⁺GFP^low); scale bars represent a size of 100 µm. Results represent mean ± SEM. Significance values: *p < 0.05; **p < 0.01; ***p < 0.001; ns not significant