Figure 1. Endothelial cells and perivascular stromal cells are the major sources of Cxcl12 in bone marrow.

a–c, In Cxcl12^DsRed/+ mice, DsRed was primarily expressed by perivascular cells throughout the bone marrow. d–f, Cxcl12-DsRed and Scf-GFP expression strongly overlapped around sinusoids throughout the bone marrow of Scf^gfp/+; Cxcl12^DsRed/+ mice. g–i, Col2.3-GFP⁺ bone-lining osteoblasts expressed Cxcl12-DsRed in the bone marrow of Col2.3-GFP⁺; Cxcl12^DsRed/+ mice. Nuclei were stained with 4′, 6-diamidino-2-phenylindole (DAPI, blue) in c, f and i. j, CD45/Ter119⁻Scf-GFP⁺ perivascular stromal cells expressed Cxcl12-DsRed in Scf^gfp/+; Cxcl12^DsRed/+ (blue histogram) but not in Scf^gfp/+ control marrow (red histogram). k, CD45/Ter119⁻Cxcl12-DsRed^high cells expressed Scf-GFP in Scf^gfp/+; Cxcl12^DsRed/+ (blue) but not in Cxcl12^DsRed/+ control marrow (red). l, CD45/Ter119⁻PDGFRα⁺ perivascular stromal cells expressed Cxcl12-DsRed in Cxcl12^DsRed/+ (blue) but not control (+/+; red) marrow. m, VE-cadherin⁺ endothelial cells expressed Cxcl12-DsRed in Cxcl12^DsRed/+ (blue) but not control (+/+; red) marrow. n, 0.5% of CD45/Ter119⁺ haematopoietic cells expressed Cxcl12-DsRed in Cxcl12^DsRed/+ but not in control marrow (Supplementary Fig. 1g). o, CD45/Ter119⁻Col2.3-GFP⁺ osteoblasts from enzymatically dissociated bone expressed Cxcl12-DsRed in Col2.3-GFP; Cxcl12^DsRed/+ (blue) but not Col2.3-GFP control (red) mice. p, Cxcl12 transcript levels by qRT-PCR in different subpopulations of bone marrow cells (n=3–6). BM, whole bone marrow cells. Peri, EYFP⁺ perivascular stromal cells from Lepr-cre; loxpEYFP mice. Endo, VE-cadherin⁺ bone marrow endothelial cells. Ob, Col2.3-GFP⁺ osteoblasts. Hema, CD45/Ter119⁺Cxcl12-DsRed⁺ haematopoietic cells. All data represent mean±s.d. from at least three independent experiments. Two-tailed student’s t-tests were always used to assess statistical significance (*P<0.05, **P<0.01, ***P<0.001). Scale bars are 20 um.