Reconstituted SCD mouse BM cells lead to vascular defects and disrupt the CXCL12⁺ hematopoietic niche in the BM. Eight-week-old C57BL/6 WT (A-C) or CXCL12-GFP⁺ healthy (D-E) mice were reconstituted with BM cells (1 × 10⁶ cells per mouse) from AA or SS mice after lethal-dose whole-body irradiation. Four weeks after transplantation, reconstituted SCD mice were euthanized for BM niche analysis. (A) Representative 3D reconstructed confocal images of the femoral diaphysis, as described in Figure 1A. Scale bar = 200 μm. (B) HbS analysis of PB by HPLC (left panels). Spleen images from AA → WT or SS → WT chimera mice (right panel). (C) Hypoxia-induced signaling was analyzed in digested BM (dBM) cells, as described in Figure 3C. Representative blots of 4 independent experiments are shown. Fold change (Δ) in band intensity of proteins and p44/42 MAPK phosphorylation were normalized to β-actin and p44/42 MAPK protein loading, respectively, and shown as mean ± standard error of the mean (SEM) (n = 4; 12 weeks old, 2 female mice and 2 male mice). (D) Representative 2D images of the femoral diaphyses are shown from reconstituted AA → CXCL12-GFP⁺ or SS → CXCL12-GFP⁺ healthy mice using LaSC. Femoral sections of 12-week-old chimera mice were stained with endoglin, followed by nuclear DAPI staining. Endoglin⁺ sinusoidal events and CXCL12-GFP^hi CAR events are contoured by iCys LaSC software, as shown in supplemental Figure 5. (E) Quantitative analysis of perisinusoidal CXCL12-GFP^hi CAR numbers was performed using iCys LaSC software. Data are mean + SEM (n = 4; 12 weeks old; 2 female mice and 2 male mice). *P < .05, **P < .01, ***P < .001, 2-tailed unpaired Student t test. M.W., molecular weight.