Rapid and efficient homing of human CD34+CD38−/lowCXCR4+stem and progenitor cells to the bone marrow and spleen of NOD/SCID and NOD/SCID/B2mnull mice

Abstract

Stem cell homing into the bone microenvironment is the first step in the initiation of marrow-derived blood cells. It is reported that human severe combined immunodeficient (SCID) repopulating cells home and accumulate rapidly, within a few hours, in the bone marrow and spleen of immunodeficient mice previously conditioned with total body irradiation. Primitive CD34 ؉ CD38 ؊/low CXCR4 ؉ cells capable of engrafting primary and secondary recipient mice selectively homed to the bone marrow and spleen, whereas CD34 ؊ CD38 ؊/low Lin ؊ cells were not detected. Moreover, whereas freshly isolated CD34 ؉ CD38 ؉/high cells did not home, in vivo stimulation with granulocyte colony-stimulating factor as part of the mobilization process, or in vitro stem cell factor stimulation for 2 to 4 days, potentiated the homing capabilities of cytokinestimulated CD34 ؉ CD38 ؉ cells. Homing of enriched human CD34 ؉ cells was inhibited by pretreatment with anti-CXCR4 antibodies. Moreover, primitive CD34 ؉ -CD38 ؊/low CXCR4 ؉ cells also homed in response to a gradient of human stromal cell-derived factor 1 (SDF-1), directly injected into the bone marrow or spleen of nonirradiated NOD/SCID mice. IntroductionDuring development hematopoietic stem cells migrate from the fetal liver into the bone marrow (BM) and continuously produce maturing hematopoietic cells that are released into the blood circulation. Hematopoietic stem cells are functionally defined, based on their ability to home to the BM microenvironment and to durably repopulate transplanted recipients with both myeloid and lymphoid cells. [1][2][3] In vivo repopulating assays for human stem cells have been developed by several groups, including ours. [4][5][6][7] In these assays human severe combined immunodeficient (SCID) repopulating cells (SRCs), characterized as CD34 ϩ CD38 Ϫ or as CD34 ϩ CD38 Ϫ/low cells, engraft the BM of sublethally irradiated immune-deficient NOD/ SCID and NOD/SCID/B2m null mice with high levels of myeloid and lymphoid cells. 7,8 Other primitive cells such as CD34 ϩ CD38 ϩ or CD34 Ϫ CD38 Ϫ cells were also found to have limited repopulation potential. 9,10 The chemokine stromal cell-derived factor 1 (SDF-1), which is also secreted by stromal cells in the BM microenvironment, was shown to attract human CD34 ϩ cells in vitro. [11][12][13] Recently we reported that engraftment of human SRC is dependent on the expression of SDF-1 and its receptor CXCR4, recharacterizing SRCs as CD34 ϩ CD38 Ϫ/low CXCR4 ϩ cells with major stem cell properties. 14 To home from the blood circulation into the BM microenvironment, hematopoietic stem and progenitor cells must first roll on E and P selectins, which are expressed on the BM vascular endothelial cells. [15][16][17] Following firm arrest and adhesion to the vessel wall under shear flow, a process mediated by the major integrins (VLA-4, VLA-5, and LFA-1) and their vascular ligands (VCAM-1 and ICAM-1), the cells extravasate through the endothelium into the hematopoietic compartment. 18-22 SDF-1 is constitutively expressed by ...

CXCR4 chemokine receptors (CD184) and α4β1 integrins mediate spontaneous migration of human CD34+ progenitors and acute myeloid leukaemia cells beneath marrow stromal cells (pseudoemperipolesis)

“…A CXCR4-negative progenitor cell line (Kasumi-1) did not display pseudoemperipolesis. The SDF-1/ CXCR4 axis and binding of a4b1 and a5b1 integrins has recently been demonstrated to be involved in the transendothelial migration of haematopoietic progenitor cells (HPC) (Mohle et al, 1998;Jo et al, 2000;Peled et al, 2000), in the rolling and arrest of HPC on vascular endothelial cells under shear flow (Peled et al, 1999b), and in human HPC mobilization and homing (Prosper et al, 1998;Peled et al, 1999a;Kollet et al, 2001). It has also been demonstrated that HSC are uniquely selective in their chemotactic responsiveness to SDF-1, suggesting that this chemokine is the key factor for homing of HSC to the marrow that cooperates with integrins, in particular a4b1 integrins (Wright et al, 2002).…”

“…During this multistep process, circulating HSC must first interact with marrow endothelial cells, followed by rolling, firm adhesion and extravasation into the haematopoietic compartment. Pretreatment of human HSC with anti-CXCR4 or anti-VLA-4 or anti-VLA-5 mAbs prevented engraftment in NOD/SCID mice (Peled et al, 1999a(Peled et al, , 2000Kollet et al, 2001), and systemic SDF-1 overexpression results in the mobilization of HSC (Hattori et al, 2001). Collectively, these observations indicate that, in vivo, a gradient of SDF-1 attracts and retains HSC within the marrow microenvironment.…”

Characterization of the growth modulatory activities of osteoblast conditioned media on cord blood progenitor cells

“…cells than MSC. Culture of CB cells in M-OST CM (OCM) and to a lesser extent MSC CM also resulted in increased frequency of cells positive for the cell-surface expression of C-X-C chemokine receptor type 4 (CxCR4) implicated in the HSPC homing to the BM (Peled et al 1999;Kollet et al 2001;Peled et al 2000). Importantly, OCM was shown to modulate the engraftment properties of expanded HSPC.…”

The CXCR4 antagonist AMD3100 impairs survival of human AML cells and induces their differentiation

“…7,8 In transplanted NOD/SCID mice, homing and subsequent engraftment of human normal or AML stem cells are dependent on the expression of cell surface CXCR4 and SDF-1 produced within the murine. [9][10][11][12] In addition to controlling cell motility, SDF-1 regulates cell proliferation, induces cell cycle progression and acts as a survival factor for normal human stem cells and AML cells. [13][14][15][16] CXCR4 blockage in AML cells, using the polypeptide RCP168, enhanced chemotherapy-induced apoptosis in vitro.…”