Neuropilin 1 regulates bone marrow vascular regeneration and hematopoietic reconstitution

AbstractIonizing radiation and chemotherapy deplete hematopoietic stem cells and damage the vascular niche wherein hematopoietic stem cells reside. Hematopoietic stem cell regeneration requires signaling from an intact bone marrow (BM) vascular niche, but the mechanisms that control BM vascular niche regeneration are poorly understood. We report that BM vascular endothelial cells secrete semaphorin 3 A (SEMA3A) in response to myeloablation and SEMA3A induces p53 – mediated apoptosis in BM endothelial cells via signaling through its receptor, Neuropilin 1 (NRP1), and activation of cyclin dependent kinase 5. Endothelial cell – specific deletion of Nrp1 or Sema3a or administration of anti-NRP1 antibody suppresses BM endothelial cell apoptosis, accelerates BM vascular regeneration and concordantly drives hematopoietic reconstitution in irradiated mice. In response to NRP1 inhibition, BM endothelial cells increase expression and secretion of the Wnt signal amplifying protein, R spondin 2. Systemic administration of anti - R spondin 2 blocks HSC regeneration and hematopoietic reconstitution which otherwise occurrs in response to NRP1 inhibition. SEMA3A – NRP1 signaling promotes BM vascular regression following myelosuppression and therapeutic blockade of SEMA3A – NRP1 signaling in BM endothelial cells accelerates vascular and hematopoietic regeneration in vivo.

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Transplanted adult hematopoietic stems cells differentiate into functional endothelial cells

Blood ◽

10.1182/blood-2003-05-1684 ◽

2004 ◽

Vol 103 (1) ◽

pp. 13-19 ◽

Cited By ~ 188

Author(s):

Alexis S. Bailey ◽

Shuguang Jiang ◽

Michael Afentoulis ◽

Christina I. Baumann ◽

David A. Schroeder ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Endothelial Cells ◽

Endothelial Cell ◽

Hematopoietic Stem Cells ◽

Blood Vessels ◽

Cell Potential ◽

Hematopoietic Stem ◽

Adult Bone Marrow ◽

Adult Bone

Abstract During early embryogenesis, blood vessels and hematopoietic cells arise from a common precursor cell, the hemangioblast. Recent studies have identified endothelial progenitor cells in the peripheral blood, and there is accumulating evidence that a subset of these cells is derived from precursors in the bone marrow. Here we show that adult bone marrow–derived, phenotypically defined hematopoietic stem cells (c-kit+, Sca-1+, lineage–) give rise to functional endothelial cells. With the exception of the brain, donor-derived cells are rapidly integrated into blood vessels. Durably engrafted endothelial cells express CD31, produce von Willebrand factor, and take up low-density lipoprotein. Analysis of DNA content indicates that donor-derived endothelial cells are not the products of cell fusion. Self-renewal of stem cells with hematopoietic and endothelial cell potential was revealed by serial transplantation studies. The clonal origin of both hematopoietic and endothelial cell outcomes was established by the transfer of a single cell. These results suggest that adult bone marrow–derived hematopoietic stem cells may serve as a reservoir for endothelial cell progenitors.

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Pleiotrophin Regulates the Retention and Self-Renewal of Hematopoietic Stem Cells in the Bone Marrow Vascular Niche

Cell Reports ◽

10.1016/j.celrep.2012.09.002 ◽

2012 ◽

Vol 2 (4) ◽

pp. 964-975 ◽

Cited By ~ 80

Author(s):

Heather A. Himburg ◽

Jeffrey R. Harris ◽

Takahiro Ito ◽

Pamela Daher ◽

J. Lauren Russell ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Hematopoietic Stem Cells ◽

Self Renewal ◽

Hematopoietic Stem ◽

Vascular Niche ◽

Bone Marrow Vascular Niche

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The Dynamic Interface Between the Bone Marrow Vascular Niche and Hematopoietic Stem Cells in Myeloid Malignancy

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.635189 ◽

2021 ◽

Vol 9 ◽

Author(s):

Laura Mosteo ◽

Joanna Storer ◽

Kiran Batta ◽

Emma J. Searle ◽

Delfim Duarte ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Hematopoietic Stem Cells ◽

Hematopoietic Stem ◽

Vascular Niche ◽

Dynamic Interface ◽

Bone Marrow Vascular Niche ◽

Bidirectional Interactions ◽

Vascular Compartment

Hematopoietic stem cells interact with bone marrow niches, including highly specialized blood vessels. Recent studies have revealed the phenotypic and functional heterogeneity of bone marrow endothelial cells. This has facilitated the analysis of the vascular microenvironment in steady state and malignant hematopoiesis. In this review, we provide an overview of the bone marrow microenvironment, focusing on refined analyses of the marrow vascular compartment performed in mouse studies. We also discuss the emerging role of the vascular niche in “inflamm-aging” and clonal hematopoiesis, and how the endothelial microenvironment influences, supports and interacts with hematopoietic cells in acute myeloid leukemia and myelodysplastic syndromes, as exemplar states of malignant myelopoiesis. Finally, we provide an overview of strategies for modulating these bidirectional interactions to therapeutic effect in myeloid malignancies.

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Hemangiogenic Role of ELF4 in Bone Marrow Post Myeloablation.

Blood ◽

10.1182/blood.v108.11.1783.1783 ◽

2006 ◽

Vol 108 (11) ◽

pp. 1783-1783

Author(s):

Mariela Sivina ◽

Takeshi Yamada ◽

Natalie Dang ◽

H. Daniel Lacorazza

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Endothelial Cells ◽

Hematopoietic Stem Cells ◽

Blood Vessels ◽

Progenitor Cells ◽

Endothelial Progenitor Cells ◽

Bone Marrow Cells ◽

Hematopoietic Stem ◽

Huvec Cells

Abstract Bone marrow suppression is an important cause of death in patients exposed to radiation or in cancer patients treated with conventional chemotherapeutic agents. Myeloablative treatments (i.e. 5-fluorouracil administration) lead to apoptosis of blood forming cells and to regression of blood vessels in bone marrow. It is well known that hematological recovery post-bone marrow insult depends on the capacity of hematopoietic stem cells to regenerate the entire hematopoietic system, however, the transcriptional machinery involved in the regeneration of sinusoidal blood vessels in bone marrow from endothelial progenitor cells is largely unknown. Endothelial cells express the Tie2 receptor tyrosine kinase (a.k.a. Tek), which is involved in the angiogenic remodeling and vessel stabilization. Gene targeting of Tie2 showed that it is not required for differentiation and proliferation of definitive hematopoietic lineages in the embryo although Tie2 is needed during postnatal bone marrow hematopoiesis. ELF is a subgroup of the ETS family of transcription factors composed by ELF1, ELF2 (a.k.a. NERF), ELF3, ELF4 (a.k.a. MEF) and ELF5. ELF1 and ELF2 have been shown to regulate Tie2 expression in vitro. Recently we showed that ELF4 modulates the exit of hematopoietic stem cells (HSC) from quiescence (Lacorazza et al., Cancer Cell2006, 9:175–187). Given the high homology between ELF1 and ELF4 and the same origin of HSC and endothelial progenitor cells, we hypothesize that ELF4 regulates proliferation and Tie2 expression of endothelial cells. We used a luciferase gene reporter system in COS-7 and HEK cells to examine the capacity of ELF proteins to activate Tie2. ELF4 is the strongest activator of Tie2 expression following the hierarchy ELF4>ELF1>ELF2 variant 1>ELF2 variant 2. Site directed mutagenesis of each of the five ETS-binding sites (EBS) present in the Tie2 promoter shows that ELF4 binds preferentially to EBS 1, 3 and 5. Binding of ELF4 to the Tie2 promoter was confirmed by chromatin immunoprecipitation and EMSA. Although Elf1 gene expression is essentially normal in Elf4−/− bone marrow cells collected after 5-FU treatment, we detected diminished Tie2 expression compared to Elf4+/+ bone marrow cells. The association of this effect to human endothelial cells derived from umbilical cord (HUVEC cells) was investigated. All-trans retinoic acid (ATRA) and vascular-endothelial growth factor (VEGF) induced ELF4 expression in HUVEC cells in a dose and time dependent manner which was followed by increased Tie2 expression, suggesting that expression of ELF4 is modulated by angiogenic signals. Moreover, endothelial cells treated with ATRA showed rapid wound colonization in a wound assay. Expression of the pan-endothelial marker MECA-32 was determined by immunohistochemistry to correlate Tie2 with the regeneration of blood vessels: myeloablated Elf4−/− femurs exhibited a reduction of MECA-32 positive arterioles. Finally, temporal and spatial expression of Tie2 during hematological recovery post ablation was measured in bone marrow using transgenic Tie2-LacZ mice crossed to Elf4−/− mice. Collectively, our data suggests that ELF4 regulates Tie2 expression in endothelial cells but most importantly their proliferative capacity in response to angiogenic signals.

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Hematopoietic Stem Cells Mediate the Repair of Damaged Endothelium

Blood ◽

10.1182/blood.v112.11.5458.5458 ◽

2008 ◽

Vol 112 (11) ◽

pp. 5458-5458

Author(s):

Dana L. Pfaffle ◽

Shuguang Jiang ◽

Devorah C. Goldman ◽

William H. Fleming

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Endothelial Cells ◽

Portal Vein ◽

Hematopoietic Stem Cells ◽

Retention Capacity ◽

Hematopoietic Stem ◽

Chase Period ◽

Portal Veins ◽

Short Term Experiment

Abstract Recent studies indicate that vascular endothelium is an important component of the hematopoietic niche. As endothelial cells (ECs) are sensitive to radiation-induced damage, we evaluated the potential role of hematopoietic stem cells to enhance EC proliferation and repair. To test this hypothesis, lethally irradiated mice were transplanted with either 200–500 c-kit+, Sca+, lineage- (KSL) cells or an equivalent dose of unfractionated bone marrow (BM) cells (1×106 cells). Control groups included irradiated, non-transplanted, and non-irradiated, non-transplanted mice. Immediately after irradiation, all recipients were maintained on 0.8mg/ml Bromodeoxyuridine (BrdU) -containing water. Eleven days following irradiation, liver tissue was harvested and the fraction of proliferating BrdU+ ECs in the portal vein was assessed by immunostaining using both light and fluorescence microscopy. In irradiated, non-transplanted mice, 0.95% ± 0.17 SEM of portal vein ECs demonstrated the incorporation of BrdU. Transplantation of KSL cells increased the frequency of proliferating endothelial cells 2.5-fold to 2.5% ± 0.20 (p<0.0006). The transplantation of an equivalent number of unfractionated BM cells further increased the frequency of proliferating ECs by more than 3.5-fold (3.75% ± 0.21; p<0.0005). In non-transplanted, non-irradiated mice, BrdU+ ECs were detected at an intermediate level (2.30% ± 0.24) that is significantly higher than irradiated nontransplant recipients (p<0.006). To gain a better understanding of how hematopoietic stem cells (HSCs) influence the label retention capacity of ECs, we performed a BrdU pulse-chase experiment. Lethally irradiated mice were transplanted with 200 KSL cells, allowed 4 weeks for recovery, and then maintained on BrdU drinking water for 4 weeks. Consistent with our findings from the short term experiment described above, significantly more BrdU+ ECs were detected in the portal veins of KSL transplanted mice (15.36% ± 2.07) compared to those in non-transplanted, non-irradiated mice (8.68% ± 0.54; p<0.04) at the start of the chase period. During the first 24 weeks of the washout phase, BrdU+ ECs declined at a greater rate in the KSL recipients than in controls, indicating increased EC turnover. Interestingly, however, in both experimental groups, BrdU retention plateaued at 24 weeks and remained constant through 36 weeks. Taken together, our results indicate that radiation damage suppresses the incorporation of BrdU into ECs compared to steady state conditions and that this suppression can be reversed by the transplantation of either hematopoietic stem cells or unfractionated bone marrow. The extent to which BM derived ECs contribute to the proliferating EC pool will be addressed in future studies.

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Donor-Derived Hematopoietic Stem Cells Repair the Bone Marrow Sinusoids Following Bone Marrow Transplant.

Blood ◽

10.1182/blood.v106.11.1714.1714 ◽

2005 ◽

Vol 106 (11) ◽

pp. 1714-1714

Author(s):

William B. Slayton ◽

Xiao-Miao Li ◽

Steven M. Guthrie ◽

Marda L. Jorgensen ◽

John R. Wingard ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Endothelial Cells ◽

Hematopoietic Stem Cells ◽

Y Chromosome ◽

Marrow Transplant ◽

Green Fluorescence ◽

Hematopoietic Stem ◽

Post Transplant ◽

Megakaryocyte Progenitors

Abstract Marrow sinusoidal capillaries provide a niche for megakaryocyte progenitors and possibly hematopoietic stem cells. We sought to determine the fate of host sinusoidal capillaries during marrow transplant. We transplanted whole bone marrow, 2000 sorted Linneg Sca-1pos c-kitpos (SKL) hematopoietic stem and progenitor cells, or single SKL cells (along with rescue marrow) from male mice expressing green fluorescent protein into lethally irradiated female C57/BL6 hosts. We used green fluorescence and the presence of the Y-chromosome to identify donor-derived cells. Sinusoidal engraftment was studied from day 5 up to 1 year post-transplant and in secondary transplants. We identified numerous donor-derived cells based on green fluorescence or presence of the Y chromosome lining the sinusoids, but it was unclear whether these cells were vascular or hematopoietic. Furthermore, we were unable to demonstrate expression of von Willebrand factor, CD31 and MECA-32 using immunohistochemistry in healthy sinusoids. We used two methods to definitively identify donor-derived endothelial cells. First, we identified these cells based on location, characteristic shape and nuclei on H&E stained sections. Serial high power fields were photographed and then the same sections were stained with X and Y FISH probes. Second, we identified donor endothelial cells based on uptake of intravenously injected Ac-LDL which was endocytosed predominantly by sinusoidal endothelial cells four hours after injection. Flushed femoral bone marrow was treated with dispase and collagenase, and disaggregated cells were lineage depleted with a standard lineage cocktail containing Mac-1 antibody. Cytospins were photographed, Ac-LDL staining cells identified, and the same cytospins were stained with X and Y FISH probes. We counted numerous donor-derived endothelial cells whether 2X106 whole bone marrow (n=6 ), 2X104 SKL cells (n=6), or single SKL cells (n=2) were transplanted. These donor-derived endothelial cells were functional based on their ability to uptake DiI AcLDL. These cells appeared adjacent to mature, donor-derived megakaryocytes, suggesting function as a niche for megakaryocyte progenitors. Furthermore, donor-derived endothelial cells were present at levels similar to hematopoietic engraftment in every animal analyzed, suggesting robust levels of repair. Single cell transplants were assessed at seven and nine months, and in secondary transplants, establishing that these cells self-renew. To determine the mechanism whereby HSC’s repair the bone marrow sinusoids, we measured the expression of stromal derived factor-1 (SDF-1) at various time points during the first two weeks post-transplant by semi-quantitative RT-PCR, ELISA, and immunohistochemistry. SDF-1 expression peaked 3 days post-transplant and was expressed primarily by damaged blood vessels. The temporal and spatial pattern of engraftment matched expression patterns of SDF-1. This study demonstrates repair of host sinusoids by donor-derived endothelial cells following transplant, with levels of reconstitution similar to that of the hematopoietic system. This repair may be mediated by expression of SDF-1 by damaged marrow vasculature. Repair of sinusoidal capillaries may be a primary role of the HSC during transplant that is necessary for successful hematopoietic engraftment.

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The Endothelial Antigen ESAM Marks Hematopoietic Stem Cells throughout Life

Blood ◽

10.1182/blood.v112.11.727.727 ◽

2008 ◽

Vol 112 (11) ◽

pp. 727-727 ◽

Cited By ~ 1

Author(s):

Takafumi Yokota ◽

Kenji Oritani ◽

Stefan Butz ◽

Koichi Kokame ◽

Paul W Kincade ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Endothelial Cell ◽

Hematopoietic Stem Cells ◽

Blood Cells ◽

Fetal Liver ◽

Side Population ◽

Expression Profiles ◽

Hematopoietic Stem

Abstract Hematopoietic stem cells (HSC) are an important cell type with the capacity for self-renewal as well as differentiation into multi-lineage blood cells, maintaining the immune system throughout life. Many studies have attempted to identify unique markers associated with these extremely rare cells. In bone marrow of adult mice, the Lin-c-kitHi Sca1+ CD34−/Lo Thy1.1Lo subset is known to include HSC with long-term repopulating capacity. However, several of these parameters differ between strains of mice, change dramatically during developmental age and/or are expressed on many non-HSC during inflammation. Efficient HSC-based therapies and the emerging field of regenerative medicine will benefit from learning more about what defines stem cells. We previously determined that the most primitive cells with lymphopoietic potential first develop in the paraaortic splanchnopleura/aorta-gonad-mesonephros (AGM) region of embryos using Rag1/GFP knock-in mice. We also reported that Rag1/GFP-c-kitHi Sca1+ cells derived from E14.5 fetal liver (FL) reconstituted lympho-hematopoiesis in lethally irradiated adults, while Rag1/GFPLo c-kitHi Sca1+ cells transiently contributed to T and B lymphopoiesis. To extend those findings, microarray analyses were conducted to search for genes that characterize the initial transition of fetal HSC to primitive lymphopoietic cells. The comparisons involved mRNA from Rag1Lo ckitHi Sca1+, early lymphoid progenitors (ELP) and the HSC-enriched Rag1-ckitHi Sca1+ fraction isolated from E14.5 FL. While genes potentially related to early lymphopoiesis were discovered, our screen also identified genes whose expression seemed to correlate with HSC. Among those, endothelial cell-selective adhesion molecule (ESAM) attracted attention because of its conspicuous expression in the HSC fraction and sharp down-regulation on differentiation to ELP. ESAM was originally identified as an endothelial cell-specific protein, but expression on megakaryocytes and platelets was also reported (J. Biol. Chem., 2001, 2002). Flow cytometry analyses with anti-ESAM antibodies showed that the HSC-enriched Rag1-c-kitHi Sca1+ fraction could be subdivided into two on the basis of ESAM levels. The subpopulation with the high density of ESAM was enriched for c-kitHi Sca1Hi cells, while ones with negative or low levels of ESAM were found in the c-kitHi Sca1Lo subset. Among endothelial-related antigens on HSC, CD34 and CD31/PECAM1 were uniformly present on Rag1-c-kitHi Sca1+ cells in E14.5 FL and neither resolved into ESAMHi and ESAM−/Lo fractions. Expression profiles of Endoglin and Tie2 partially correlate with ESAM. The primitive ESAMHi fraction uniformly expressed high levels of Endoglin and Tie2, but many of the more differentiated ESAM−/Lo cells still retained the two markers. ESAM expression correlated well with HSC activity. Cells in the ESAMHi Rag1-ckitHi Sca1+ fraction formed more and larger colonies than those in the ESAM-/Lo Rag1-ckitHi Sca1+ fraction. Particularly, most CFU-Mix, primitive progenitors with both myeloid and erythroid potential, were found in the ESAMHi fraction. In limiting dilution stromal cell co-cultures, we found that 1 in 2.1 ESAMHi Rag1-ckitHi Sca1+ cells and 1 in 3.5 ESAM−/Lo Rag1-ckitHi Sca1+ cells gave rise to blood cells. However, while only 1 in 125 ESAM−/Lo Rag1-ckitHi Sca1+ cells were lymphopoietic under these conditions, 1 in 8 ESAMHi Rag1-ckitHi Sca1+ cells produced CD19+ B lineage cells. In long-term reconstituting assays, ESAMHi Rag1-ckitHi Sca1+ cells contributed highly to the multi-lineage recovery of lympho-hematopoiesis in recipients, but no chimerism was detected in mice transplanted with ESAM−/Lo Rag1-ckitHi Sca1+ cells. These results suggested that HSC in E14.5 FL are exclusively present in the ESAMHi fraction. Tie2+ c-kit+ lympho-hematopoietic cells of E10.5 AGM also expressed high levels of ESAM. Furthermore, ESAM expression in adult bone marrow was detected on primitive progenitors and cells in the side population within the Lin-ckitHi Sca1+ fraction. Interestingly, the expression was up-regulated in aged mice. Based on these observations, we conclude that ESAM marks HSC throughout life in mice. We also observed that many of human cord blood CD34+ CD38− cells express ESAM, suggesting potential application for the purification of human HSC.

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Connexin-43 Expression Regulates the Migration of Hematopoietic Stem Cells and Progenitors towards and From Bone Marrow.

Blood ◽

10.1182/blood.v114.22.562.562 ◽

2009 ◽

Vol 114 (22) ◽

pp. 562-562

Author(s):

Daniel Gonzalez-Nieto ◽

Kyung-Hee Chang ◽

Anja Koehler ◽

Jorden Arnett ◽

Susan Dunn ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Endothelial Cells ◽

Hematopoietic Stem Cells ◽

Connexin 43 ◽

Cell Types ◽

Loss Of Function ◽

Hematopoietic Stem ◽

Hematopoietic Microenvironment ◽

Deficient Mice

Abstract Abstract 562 In the bone marrow (BM) cavity, the migratory traffic of hematopoietic stem cells and progenitors (HSC/P) from the endosteal niches to circulation and viceversa depends on their response to chemokine gradients and interaction with endothelial and mesenchymal pre-osteoblastic cells located at the endosteal niches, forming the hematopoietic microenvironment (HM). Several lines of evidence have pointed out the possible role of the gap junction-forming protein connexin-43 (Cx43) in the control of stem cell and progenitor migration. Our group previously demonstrated that Cx43 expression in the hematopoietic microenvironment (HM) is critical in the fetal liver and BM hematopoietic regeneration after administration of 5-fluorouracil (5-FU) and other investigators have shown that Cx43 is crucial controlling the migration of neural progenitors along radial glial during brain development. We hypothesized that Cx43 could regulate the bidirectional migration of HSC/P in the BM stroma. Since Cx43 is expressed by mesenchymal cells, endothelial cells and hematopoietic stem cells and progenitors, we decided to analyze the Cx43 contribution in the control of HSC/P migration in cell-specific conditional knock-out mice. To achieve this objective, we have used mice that were selectively deficient for Cx43 in the osteoblast/stromal cells (Collagen 1a-Creflox/flox; O/S-Cx43-deficient), in endothelial cells (Tek-Creflox/flox; E-Cx43-deficient) or in hematopoietic cells (Vav1-Creflox/flox; H-Cx43-deficient). O/S-Cx43-deficient mice have been shown to be a model of osteoblast loss of function (Chung DJ et al., J. Cell. Sci., 2006) and E-Cx43-deficient mice have been shown to be a model of arterial hypotension induced by both increase nitric oxide and angiotensin levels (Liao Y et al, PNAS 2001). Analysis with reporter crossings with Rosa-loxP-Stop-LoxP-LacZ mice showed anatomical specificity of the Cre recombinase expression in different cell types of BM, and western-blot and RT-PCR expression indicated practical abolishment of the expression of Cx43 in each of the specific cell types. First, we analyzed whether there were changes in the levels of circulating progenitors in O/S-, E- or H-Cx43-deficient mice. While H-Cx43-deficient mice did not show any change in the levels of circulating HSC/P, E-Cx43-deficient mice showed a 3.5-fold and 4.7-fold, respectively, increase of circulating CFU-C and competitive repopulating units while maintaining normal repopulation ability of BM HSC. O/S-Cx43-deficient mice showed a 30% reduction in basal conditions which was more accentuated when administered G-CSF (50% reduction on day +6), compared with their WT counterparts. Interestingly, while osteoblast loss-of-function was induced in O/S Cx43-deficient mice, the intramarrow expression levels of CXCL12a/b and mesenchymal progenitor content (CFU-F) were increased (4- and 2-fold, respectively). In correlation with the increased levels of CXCL12, the distance to endosteum of transplanted CFSE+/lin-/c-kit+ BM cells into non-myeloablated O/S-Cx43-deficient mice was dramatically decreased (36.1±4.3 vs 23.2±2.1 mm, p<0.01), suggesting a major change in the cellular composition and chemokinesis within the hematopoietic microenvironment “in vivo”. Interestingly, the 16-hour homing of HSC/P transplanted into lethally irradiated O/S-Cx43KO recipient mice showed a ∼60% reduction and a significantly decreased survival in a limiting-dose transplantation radioprotection assay (50% survival in WT mice vs 0% survival in O/S Cx43-deficient recipients). The homing/engraftment defect of these mice correlated with a reversal of the increased levels of CXCL12 in irradiated BM and a 50% reduction of the migration of WT HSC/P through O/S-Cx43-deficient stroma in response to CXCL12. Altogether, these data indicate that intercellular communication through Cx43 shares distinct functions between the different cell components of the hematopoietic microenvironment, and mediates CXCL12-dependent and CXCL12-independent mechanisms in control of the BM homing and retention of HSC/P. Disclosures: No relevant conflicts of interest to declare.

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Role of microvascular endothelial cells on proliferation, migration and adhesion of hematopoietic stem cells

Bioscience Reports ◽

10.1042/bsr20192104 ◽

2020 ◽

Vol 40 (3) ◽

Author(s):

Fanli Lin ◽

Shuyue Wang ◽

Hao Xiong ◽

Yang Liu ◽

Xiaoming Li ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Endothelial Cells ◽

Hematopoietic Stem Cells ◽

Ex Vivo ◽

Microvascular Endothelial Cells ◽

Cell Contact ◽

Hematopoietic Stem ◽

Direct Cell ◽

Cell Cell

Abstract Background: The present study investigated the effects of microvascular endothelial cells (MECs) on the chemotaxis, adhesion and proliferation of bone marrow hematopoietic stem cells (HSCs) ex vivo. Methods and Results: MECs were collected from the lung tissue of C57BL/6 mice, and HSCs were isolated with immunomagnetic beads from bone marrow of GFP mice. MECs and HSCs were co-cultured with or without having direct cell–cell contact in Transwell device for the measurement of chemotaxis and adhesion of MECs to HSCs. Experimental results indicate that the penetration rate of HSCs from the Transwell upper chamber to lower chamber in ‘co-culture’ group was significantly higher than that of ‘HSC single culture’ group. Also, the HSCs in co-culture group were all adherent at 24 h, and the co-culture group with direct cell–cell contact had highest proliferation rate. The HSC number was positively correlated with vascular endothelial growth factor (VEGF) and stromal cell-derived factor-1 (SDF-1) levels in supernatants of the culture. Conclusions: Our study reports that MECs enhance the chemotaxis, adhesion and proliferation of HSCs, which might be related to cytokines SDF-1 and VEGF secreted by MECs, and thus MECs enhance the HSC proliferation through cell–cell contact. The present study revealed the effect of MECs on HSCs, and provided a basis and direction for effective expansion of HSCs ex vivo.

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Primary endothelial cells isolated from the yolk sac and para-aortic splanchnopleura support the expansion of adult marrow stem cells in vitro

Blood ◽

10.1182/blood-2003-03-0729 ◽

2003 ◽

Vol 102 (13) ◽

pp. 4345-4353 ◽

Cited By ~ 46

Author(s):

Weiming Li ◽

Scott A. Johnson ◽

William C. Shelley ◽

Michael Ferkowicz ◽

Paul Morrison ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Endothelial Cells ◽

Endothelial Cell ◽

Ex Vivo ◽

Yolk Sac ◽

Hematopoietic Progenitor Cell ◽

Hematopoietic Progenitor ◽

Hematopoietic Stem

AbstractThe embryonic origin and development of hematopoietic and endothelial cells is highly interdependent. We hypothesized that primary endothelial cells from murine yolk sac and para-aortic splanchnopleura (P-Sp) may possess the capacity to expand hematopoietic stem cells (HSCs) and progenitor cells ex vivo. Using Tie2-GFP transgenic mice in combination with fluorochrome-conjugated monoclonal antibodies to vascular endothelial growth factor receptor-2 (Flk1) and CD41, we have successfully isolated pure populations of primary endothelial cells from 9.5-days after coitus (dpc) yolk sac and P-Sp. Adult murine bone marrow Sca-1+c-Kit+lin- cells were cocultured with yolk sac or P-Sp Tie2-GFP+Flk-1+CD41- endothelial cell monolayers for 7 days and the total number of nonadherent cells increased 47- and 295-fold, respectively, and hematopoietic progenitor counts increased 9.4- and 11.4-fold, respectively. Both the yolk sac and P-Sp endothelial cell cocultures facilitated long-term (> 6 months) HSC competitive repopulating ability (2.8- to 9.8-fold increases, respectively). These data suggest that 9.5-dpc yolk sac- and P-Sp-derived primary Tie2-GFP+Flk-1+CD41- endothelial cells possess the capacity to expand adult bone marrow hematopoietic progenitor cell and HSC repopulating ability ex vivo. (Blood. 2003;102:4345-4353)

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