Bone Marrow Niches for Skeletal Progenitor Cells and their Inhabitants in Health and Disease

The bone marrow hosts skeletal progenitor cells which have most widely been referred to as Mesenchymal Stem or Stromal Cells (MSCs), a heterogeneous population of adult stem cells possessing the potential for self-renewal and multilineage differentiation. A consensus agreement on minimal criteria has been suggested to define MSCs in vitro, including adhesion to plastic, expression of typical surface markers and the ability to differentiate towards the adipogenic, osteogenic and chondrogenic lineages but they are critically discussed since the differentiation capability of cells could not always be confirmed by stringent assays in vivo. However, these in vitro characteristics have led to the notion that progenitor cell populations, similar to MSCs in bone marrow, reside in various tissues. MSCs are in the focus of numerous (pre)clinical studies on tissue regeneration and repair.Recent advances in terms of genetic animal models enabled a couple of studies targeting skeletal progenitor cells in vivo. Accordingly, different skeletal progenitor cell populations could be identified by the expression of surface markers including nestin and leptin receptor. While there are still issues with the identity of, and the overlap between different cell populations, these studies suggested that specific microenvironments, referred to as niches, host and maintain skeletal progenitor cells in the bone marrow. Dynamic mutual interactions through biological and physical cues between niche constituting cells and niche inhabitants control dormancy, symmetric and asymmetric cell division and lineage commitment. Niche constituting cells, inhabitant cells and their extracellular matrix are subject to influences of aging and disease e.g. via cellular modulators. Protective niches can be hijacked and abused by metastasizing tumor cells, and may even be adapted via mutual education. Here, we summarize the current knowledge on bone marrow skeletal progenitor cell niches in physiology and pathophysiology. We discuss the plasticity and dynamics of bone marrow niches as well as future perspectives of targeting niches for therapeutic strategies.

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Involvement of the Integrin Alpha 6 Receptor in the Homing and Engraftment of Hematopoietic Stem and Progenitor Cells to Bone Marrow.

Blood ◽

10.1182/blood.v104.11.1293.1293 ◽

2004 ◽

Vol 104 (11) ◽

pp. 1293-1293

Author(s):

Hong Qian ◽

Sten Eirik W. Jacobsen ◽

Marja Ekblom

Keyword(s):

Bone Marrow ◽

Stem Cell ◽

Progenitor Cells ◽

Progenitor Cell ◽

Bone Marrow Cells ◽

Hematopoietic Stem ◽

Stem And Progenitor Cells ◽

Functional Blocking

Abstract Within the bone marrow environment, adhesive interactions between stromal cells and extracellular matrix molecules are required for stem and progenitor cell survival, proliferation and differentiation as well as their transmigration between bone marrow (BM) and the circulation. This regulation is mediated by cell surface adhesion receptors. In experimental mouse stem cell transplantation models, several classes of cell adhesion receptors have been shown to be involved in the homing and engraftment of stem and progenitor cells in BM. We have previously found that integrin a6 mediates human hematopoietic stem and progenitor cell adhesion to and migration on its specific ligands, laminin-8 and laminin-10/11 in vitro (Gu et al, Blood, 2003; 101:877). Using FACS analysis, the integrin a6 chain was now found to be ubiquitously (>95%) expressed in mouse hematopoietic stem and progenitor cells (lin−Sca-1+c-Kit+, lin−Sca-1+c-Kit+CD34+) both in adult bone marrow and in fetal liver. In vitro, about 70% of mouse BM lin−Sca-1+c-Kit+ cells adhered to laminin-10/11 and 40% adhered to laminin-8. This adhesion was mediated by integrin a6b1 receptor, as shown by functional blocking monoclonal antibodies. We also used a functional blocking monoclonal antibody (GoH3) against integrin a6 to analyse the role of the integrin a6 receptor for the in vivo homing of hematopoietic stem and progenitor cells. We found that the integrin a6 antibody inhibited the homing of bone marrow progenitors (CFU-C) into BM of lethally irradiated recipients. The number of homed CFU-C was reduced by about 40% as compared to cells incubated with an isotype matched control antibody. To study homing of long-term repopulating stem cells (LTR), antibody treated bone marrow cells were first injected intravenously into lethally irradiated primary recipients. After three hours, bone marrow cells of the primary recipients were analysed by competitive repopulation assay in secondary recipients. Blood analysis 16 weeks after transplantation revealed an 80% reduction of stem cell activity of integrin a6 antibody treated cells as compared to cells treated with control antibody. These results suggest that integrin a6 plays an important role for hematopoietic stem and progenitor cell homing in vivo.

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Integrin alpha 6 Is Essential for Fetal Hematopoietic Progenitor, but Not Fetal Stem Cell Homing to Bone Marrow.

Blood ◽

10.1182/blood.v106.11.1387.1387 ◽

2005 ◽

Vol 106 (11) ◽

pp. 1387-1387

Author(s):

Hong Qian ◽

Sten Eirik W. Jacobsen ◽

Marja Ekblom

Keyword(s):

Bone Marrow ◽

Stem Cell ◽

Progenitor Cells ◽

Progenitor Cell ◽

Fetal Liver ◽

Hematopoietic Stem ◽

Stem And Progenitor Cells ◽

Integrin Alpha 6

Abstract Homing of transplanted hematopoietic stem cells (HSC) in the bone marrow (BM) is a prerequisite for establishment of hematopoiesis following transplantation. However, although multiple adhesive interactions of HSCs with BM microenviroment are thought to critically influence their homing and subsequently their engraftment, the molecular pathways that control the homing of transplanted HSCs, in particular, of fetal HSCs are still not well understood. In experimental mouse stem cell transplantation models, several integrins have been shown to be involved in the homing and engraftment of both adult and fetal stem and progenitor cells in BM. We have previously found that integrin a6 mediates human hematopoietic stem and progenitor cell adhesion to and migration on its specific ligands, laminin-8 and laminin-10/11 in vitro (Gu et al, Blood, 2003; 101:877). Furthermore, integrin a6 is required for adult mouse HSC homing to BM in vivo (Qian et al., Abstract American Society of Hematology, Blood 2004 ). We have now found that the integrin a6 chain like in adult HSC is ubiquitously (>99%) expressed also in fetal liver hematopoietic stem and progenitor cells (lin−Sca-1+c-Kit+, LSK ). In vitro, fetal liver LSK cells adhere to laminin-10/11 and laminin-8 in an integrin a6b1 receptor-dependent manner, as shown by function blocking monoclonal antibodies. We have now used a function blocking monoclonal antibody (GoH3) against integrin a6 to analyse the role of the integrin a6 receptor for the in vivo homing of fetal liver hematopoietic stem and progenitor cells to BM. The integrin a6 antibody inhibited homing of fetal liver progenitors (CFU-C) into BM of lethally irradiated recipients. The number of homed CFU-C in BM was reduced by about 40% as compared to the cells incubated with an isotype matched control antibody. To study homing of long-term repopulating stem cells, BM cells were first incubated with anti-integrin alpha 6 or anti-integrin alpha 4 or control antibody, and then injected intravenously into lethally irradiated primary recipients. After three hours, BM cells of the primary recipients were analysed by competitive repopulation assay in secondary recipients. Blood analysis up to 16 weeks after transplantation showed that no reduction of stem cell reconstitution from integrin a6 antibody treated cells as compared to cells treated with control antibody. In accordance with this, fetal liver HSC from integrin a6 gene deleted embryos did not show any impairment of homing and engraftment in BM as compared to normal littermates. These results suggest that integrin a6 plays an important developmentally regulated role for homing of distinct hematopoietic stem and progenitor cell populations in vivo.

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Dendritic Cells Direct Specific Stimulation of Hematopoietic Stem/Progenitor Cells Generating a Potentially Therapeutic Cell Population

Blood ◽

10.1182/blood.v118.21.483.483 ◽

2011 ◽

Vol 118 (21) ◽

pp. 483-483

Author(s):

Yael Porat ◽

Efrat Assa-Kunik ◽

Michael Belkin ◽

Shlomo Bulvik

Keyword(s):

Bone Marrow ◽

Progenitor Cells ◽

Hind Limb ◽

Progenitor Cell ◽

Limb Ischemia ◽

Hematopoietic Stem ◽

Equity Ownership ◽

Medium Group

Abstract Abstract 483 Background: Recent data show that dendritic cells (DCs) are important component of stem cell niches in the bone marrow and spleen, and as such may have a role in stem/progenitor cell homeostasis and in pro- and anti-angiogenic processes (Gabrilovich, 1996; Dikov, 2005; Sozzani, 2007). For the first time we report a process in which human Hematopoietic Stem/Progenitor Cells (HSPC) are specifically stimulated by activated DCs. This newly developed process makes it possible to use even unmobilized blood cells as a source for sufficient numbers of potentially therapeutic stem/progenitor cells, thus eliminating the need for surgical bone marrow harvesting and G-CSF mobilization. Goal: To show that DCs can direct the generation of an Enriched Endothelial Progenitor Cell (EnEPC) population, which includes Endothelial Progenitor Cells (EPC) and HSPCs, addressed to treat blood vessel malfunction. Methods: Samples of 250 ml blood from both healthy and diabetic patients were collected under hospital's IRB (Bulvik 15/150109) and used as the cell source. Selected immature plasmacytoid and myeloid DCs were alternatively activated for 2–24 hours in order to induce pro-angiogenic signals before being co-cultured with HSPCs. Cultures of up to 66 hours resulted in the generation of EnEPC in a formulation named BC1. BC1 was tested in-vitro by FACS, tube formation, colony forming units (CFU) and cytokine secretion tests. In-vivo BC1 was tested in the hind limb ischemia model (Goto, 2006; Kang, 2009) of critical limb ischemia (CLI) in order to evaluate its therapeutic potential, dosing levels and bio-distribution following intramuscular transplantation (IM). The study applied a genetically modified SCID/Nude mice model supporting evaluation of both safety and efficacy of BC1 treatment. A 21-day controlled blinded experiment included a control medium group (N=10); unprocessed cells (PreBC1, N=5); two BC1 groups of 2.5×10^6/mouse, BC1-1 (N=10) cultured for 1day and BC1-3 (N=10) for 3 and a lower cell dose group of 0.5×10^6/Mouse BC1-31 (N=5). Results: DC directed BC1 containing 70 ±5×10^6 cells with a viability of 96.9±1.9% is composed of a mixture of 40.2±11.9% EPC (expressing Ulex-lectin and uptake of AcLDL, CD202b (Tie2), CD309 (VEGGFR-2; KDR), CD31 and VEGFR1) and 29.8±14.3% HSPC (co-expressing CD34 and the migration/homing marker CD184 /CXCR4-R). In-vitro functional tests demonstrated angiogenic and hematopoietic potential and secretion of IL-8, VEGF, and IL-10 but not TNF and IFN. In-vivo BC1 was found efficient and safe in the hind-limb ischemia model. Evaluation of clinical signs revealed an improvement in limb function and score in all BC1 treated groups over the control medium group. BC1 treatment doubled the blood flow (BF) to the legs from an average of 23±5% after injury to an average of 51±3.1% on day 21 after treatment (p<0.005). Conclusions: The presented data show that activated DCs can direct in-vitro cellular interactions resulting in a potentially therapeutic EnEPC population after a short-term culture of HSPC. This process makes it possible to use unmobilized blood as the raw material for generating stem/progenitor cell products. The method described here is far safer for patients and much more convenient for clinicians compared to existing methods, such as G-CSF mobilization or bone marrow and fat cells harvesting. Further research needs to be done in order to test the safety and efficacy of these cells in patients suffering from cardiovascular diseases and blood vessel malfunctions. Disclosures: Porat: BioGenCell: Employment, Equity Ownership, Research Funding; Laniado Hospital: Consultancy. Assa-Kunik:BioGenCell: Employment; Laniado Hospital: Employment. Belkin:BioGenCell: Consultancy, Equity Ownership.

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Abstract 15440: Dynamics of Adipocyte and Endothelial Progenitor Cell Pools in Expanding Adipose Tissue

Circulation ◽

10.1161/circ.130.suppl_2.15440 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

Candice R Holden ◽

Marcin Wysoczynski ◽

Brian Sansbury ◽

Jason Hellmann ◽

Nagma Zafar ◽

...

Keyword(s):

Bone Marrow ◽

Adipose Tissue ◽

Stem Cell ◽

Progenitor Cells ◽

Progenitor Cell ◽

Stromal Vascular Fraction ◽

Cell Populations ◽

Adipose Organ ◽

The Impact

Objective: Obesity is a major risk factor for the development of several chronic diseases including type 2 diabetes and cardiovascular disease. Proper fat storage in white adipose tissue (WAT) is required to maintain insulin sensitivity and to preserve (cardio)vascular health. We hypothesize that endothelial and adipocyte progenitor cell populations (EPCs and APCs, respectively) must be appropriately balanced for physiological, as opposed to pathological, remodeling of WAT. Methods and Results: To determine the impact of nutrient excess on stem/progenitor cells in epididymal WAT, male C57BL/6J mice were placed on a high fat diet (HFD; 60% fat) for 12 weeks and changes in WAT stem cell populations were measured in the stromal vascular fraction by flow cytometry. Although the APC (CD24+/CD29+/Sca+/CD14-/CD45-) population, which has the capacity to differentiate into adipocytes both in vitro and in vivo , was not significantly changed with diet, Flk+/Sca+ EPCs were diminished, promoting a 4-fold decrease in the EPC/APC ratio (p <0.05, n = 6/group). To determine whether this deficit may be due to poor stem cell recruitment, mice were irradiated, and the bone marrow was repopulated with GFP+ donor marrow. The transplanted mice were then placed on a low fat diet (LFD; 10% fat) or HFD for 12 weeks, and WAT progenitor cells were again measured. Greater than 95% of the putative APCs in the WAT of HF-fed mice were GFP+ (p<0.0001, n=7-8/group), indicating a bone marrow-derived origin. Unexpectedly, less than 1% of the EPCs were GFP+ (p<0.001, n=7-8/group), which suggests that EPCs present in WAT are not derived from bone marrow in adult mice. Confocal analysis of WAT from HF-fed, bone marrow-transplanted mice showed little evidence of significant APC differentiation into triglyceride-laden adipocytes, suggesting that conditions associated with nutrient excess may impair the ability of the adipose organ to store fat properly. Conclusions: These results demonstrate that putative APCs, and not EPCs, in epididymal WAT are derived from bone marrow. Furthermore, our data suggest that conditions of nutrient excess promote an imbalance in EPCs and APCs, the stoichiometry of which may be critical for the development of new adipocytes and for proper storage of fat.

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Candidate Human Primary Mesenchymal Stem/Progenitor Cells Are Highly Enriched in Linneg/CD45neg/CD271pos/PDGFRαneg Bone Marrow Cells

Blood ◽

10.1182/blood.v120.21.3460.3460 ◽

2012 ◽

Vol 120 (21) ◽

pp. 3460-3460

Author(s):

Hongzhe Li ◽

Roshanak Ghazanfari ◽

Nicholas Ditzel ◽

Moustapha Kassem ◽

Stefan Scheding

Keyword(s):

Bone Marrow ◽

Stem Cell ◽

Progenitor Cells ◽

Stromal Cells ◽

Human Bone ◽

Human Bone Marrow ◽

Surface Markers ◽

Facs Analysis

Abstract Abstract 3460 Human bone marrow (BM) contains a rare population of non-hematopoietic mesenchymal stem cells (BM-MSC) which can differentiate toward skeletal lineages such as osteoblasts, adipocytes, chondrocytes and hematopoiesis-supporting stromal cells. In vivo, BM-MSC are essential constituents of the hematopoietic stem cell niche, thus playing an important role in supporting, maintaining and controlling hematopoiesis. We and others have previously shown that primary BM-MSC were exclusively found in the linneg/CD45neg/CD271pos cell fraction in human bone marrow, and we furthermore reported that expression of CD146 on BM-MSC correlated with in-situ localization (Tormin et al., Blood 2011,117[19]:5067–5077). Although BM-MSC were highly enriched in linneg/CD45neg/CD271pos cells as reflected by CFU-F frequencies of about 1 in 20, there was still a considerable fraction of non-colony forming cells present in this population. Therefore, the current study aimed to identify novel MSC markers that would allow for a more precise definition of the candidate stromal stem cell population in human bone marrow. Human bone marrow linneg/CD45neg cells were sorted based on CD271 expression and comparative gene expression profiling was performed using the Illumina Human HT-12 expression v4 BeadChip comprising 48,107 probes. In total, 215 genes were found to be significantly up-regulated in the linneg/CD45neg/CD271pos subset compared to linneg/CD45neg/CD271neg cells, whereas 97 genes were down-regulated. Twenty eight of the upregulated genes correlated to surface markers and expression of thirteen of them could be verified by FACS. Several of the surface markers identified by this approach, such as CD140b, CD10 and CD106 were previously described in the context of MSC isolation. However, the majority of them represented novel MSC markers including molecules such as CD151, CD81, IFNGR2, LEPR, TGFBR3, IL1R1, CD18, CD140a, and FGFR3. FACS analysis of these markers on linneg/CD45neg/CD271pos cells revealed two staining patterns, i.e. A) marker expression either correlated directly with CD271 expression, or B) the novel maker was only expressed on a fraction of linneg/CD45neg/CD271pos cells. CD151 and CD106 are examples for pattern A markers and, as expected, CFU-F frequencies in sorted linneg/CD45neg/CD271pos/CD151pos and linneg/CD45neg/CD271pos/CD106pos cells were comparable with linneg/CD45neg/CD271pos cells. Furthermore, proliferation and in-vitro/in-vivo differentiation capacities were comparable. On the other hand, using CD140a (platelet-derived growth factor receptor α, PDGFRα) - one of the pattern B markers - allowed to clearly identify a population of linneg/CD45neg/CD271pos/CD140aneg cells which were highly enriched for CFU-F (24.15 ± 4.51 CFU-Fs per 100 plated cells, n=6) compared to linneg/CD45neg/CD271pos/CD140apos cells (1.13 ± 0.65 CFU-Fs per 100 plated cells, n=6). The high CFU-F frequency in CD140aneg cells was furthermore confirmed in single cell sorting and limiting dilution experiments. Quantitative RT-PCR of sorted primary CD140neg MSC showed considerably higher expression of ALPL, PPARγ, and ACAN as well as Oct4, Sox2 and Nanog compared to CD140apos cells, and multicolor FACS analysis revealed that linneg/CD45neg/CD271pos/CD140aneg cells co-expressed typical primary MSC markers (CD90, CD105, CD140b, STRO-1), but not CD31 and CD34. Furthermore, linneg/CD45neg/CD271pos/CD140aneg cells (bulk and single cell sorted) gave rise to typical cultured MSC (expression of standard surface markers, in-vitro differentiation capacity). Moreover, linneg/CD45neg/CD271pos/CD140aneg -derived stromal cells formed bone, adipocytes and hematopoietic stroma when transplanted s.c. into NOD-SCID mice. Taken together, sorting of linneg/CD45neg/CD271pos cells based on CD140a (PDGFRα) expression enabled to isolate CFU-F with thus far unmet precision. Linneg/CD45neg/CD271pos/CD140aneg cells had typical BM-MSC properties, thus possibly representing a close to pure population of the candidate human primary mesenchymal stem/progenitor cells. These findings will enable to better characterize native BM-MSC and establish their physiological role in vivo. Disclosures: No relevant conflicts of interest to declare.

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Persistence of myeloid progenitor cells expressing BCR-ABL mRNA after allogeneic bone marrow transplantation for chronic myelogenous leukemia

Blood ◽

10.1182/blood.v84.7.2109.bloodjournal8472109 ◽

1994 ◽

Vol 84 (7) ◽

pp. 2109-2114

Author(s):

G Pichert ◽

EP Alyea ◽

RJ Soiffer ◽

DC Roy ◽

J Ritz

Keyword(s):

Bone Marrow ◽

Bone Marrow Transplantation ◽

Marrow Transplantation ◽

Progenitor Cell ◽

Allogeneic Bone Marrow Transplantation ◽

Allogeneic Bone Marrow ◽

Myeloid Differentiation ◽

Allogeneic Bone

Previous studies have shown that tumor-specific bcr-abl mRNA can often be detected by polymerase chain reaction. (PCR) for months to years after allogeneic bone marrow transplantation (BMT) for chronic myelocytic leukemia (CML). Nevertheless, the presence of bcr-abl mRNA by itself does not invariably predict for clinical relapse post-BMT. This has led to the hypothesis that bcr-abl mRNA might be expressed in cells that have lost either proliferative or myeloid differentiation potential. To directly characterize the cells detected by PCR in patients with CML after allogeneic BMT, we first identified five individuals in whom PCR-positive cells could be detected at multiple times post-BMT. Bone marrow samples from these individuals were cultured in vitro and single erythroid, granulocytic, and macrophage colonies, each containing 50 to 100 cells, were examined for the presence of bcr-abl mRNA by PCR. PCR-positive myeloid colonies could be detected in four of five individuals in marrow samples obtained 5 to 56 months post-BMT. Overall, 7 of 135 progenitor cell colonies (5.2%) were found to be PCR-positive. The expression of bcr-abl mRNA appeared to be equally distributed among committed erythroid, macrophage, and granulocyte progenitors. These patients have now been followed-up for an additional 20 to 33 months from the time of progenitor cell PCR analysis but only one of these individuals has been found to have cytogenetic evidence of recurrent Ph+ cells. These results show that long-term persistence of PCR-detectable bcr-abl mRNA after allogeneic BMT can be caused by the persistence of CML-derived clonogenic myeloid precursors that have survived the BMT preparative regimen. These cells continue to have both proliferative and myeloid differentiation capacity in vitro. Nevertheless, these PCR-positive cells do not appear to either expand or differentiate in vivo for prolonged periods, suggesting the presence of mechanisms for suppression of residual clonogenic leukemia cells in vivo.

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Heparanase regulates retention and proliferation of primitive Sca-1+/c-Kit+/Lin− cells via modulation of the bone marrow microenvironment

Blood ◽

10.1182/blood-2007-10-116145 ◽

2008 ◽

Vol 111 (10) ◽

pp. 4934-4943 ◽

Cited By ~ 27

Author(s):

Asaf Spiegel ◽

Eyal Zcharia ◽

Yaron Vagima ◽

Tomer Itkin ◽

Alexander Kalinkovich ◽

...

Keyword(s):

Bone Marrow ◽

Stem Cell ◽

Progenitor Cells ◽

Progenitor Cell ◽

Cathepsin K ◽

Hematopoietic Progenitors ◽

Hematopoietic Progenitor ◽

Cell Mobilization ◽

Tumor Growth And Metastasis

Abstract Heparanase is involved in tumor growth and metastasis. Because of its unique cleavage of heparan sulfate, which binds cytokines, chemokines and proteases, we hypothesized that heparanase is also involved in regulation of early stages of hematopoiesis. We report reduced numbers of maturing leukocytes but elevated levels of undifferentiated Sca-1+/c-Kit+/Lin− cells in the bone marrow (BM) of mice overexpressing heparanase (hpa-Tg). This resulted from increased proliferation and retention of the primitive cells in the BM microenvironment, manifested in increased SDF-1 turnover. Furthermore, heparanase overexpression in mice was accompanied by reduced protease activity of MMP-9, elastase, and cathepsin K, which regulate stem and progenitor cell mobilization. Moreover, increased retention of the progenitor cells also resulted from up-regulated levels of stem cell factor (SCF) in the BM, in particular in the stem cell–rich endosteum and endothelial regions. Increased SCF-induced adhesion of primitive Sca-1+/c-Kit+/Lin− cells to osteoblasts was also the result of elevation of the receptor c-Kit. Regulation of these phenomena is mediated by hyperphosphorylation of c-Myc in hematopoietic progenitors of hpa-Tg mice or after exogenous heparanase addition to wildtype BM cells in vitro. Altogether, our data suggest that heparanase modification of the BM microenvironment regulates the retention and proliferation of hematopoietic progenitor cells.

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Thrombopoietin, but not erythropoietin promotes viability and inhibits apoptosis of multipotent murine hematopoietic progenitor cells in vitro

Blood ◽

10.1182/blood.v88.8.2859.bloodjournal8882859 ◽

1996 ◽

Vol 88 (8) ◽

pp. 2859-2870 ◽

Cited By ~ 76

Author(s):

OJ Borge ◽

V Ramsfjell ◽

OP Veiby ◽

MJ Jr Murphy ◽

S Lok ◽

...

Keyword(s):

Bone Marrow ◽

Progenitor Cells ◽

Bone Marrow Cells ◽

Interleukin 1 ◽

Calf Serum ◽

Myeloid Cell ◽

Promoting Effect ◽

Multipotent Progenitors

The recently cloned c-mpl ligand, thrombopoietin (Tpo), has been extensively characterized with regard to its ability to stimulate the growth, development, and ploidy of megakaryocyte progenitor cells and platelet production in vitro and in vivo. Primitive hematopoietic progenitors have been shown to express c-mpl, the receptor for Tpo. In the present study, we show that Tpo efficiently promotes the viability of a subpopulation of Lin-Sca-1+ bone marrow progenitor cells. The ability of Tpo to maintain viable Lin-Sca-1+ progenitors was comparable to that of granulocyte colony-stimulating factor and interleukin-1, whereas stem cell factor (SCF) promoted the viability of a higher number of Lin-Sca-1+ progenitor cells when incubated for 40 hours. However, after prolonged (> 40 hours) preincubation, the viability-promoting effect of Tpo was similar to that of SCF. An increased number of progenitors surviving in response to Tpo had megakaryocyte potential (37%), although almost all of the progenitors produced other myeloid cell lineages as well, suggesting that Tpo acts to promote the viability of multipotent progenitors. The ability of Tpo to promote viability of Lin-Sca-1+ progenitor cells was observed when cells were plated at a concentration of 1 cell per well in fetal calf serum-supplemented and serum-depleted medium. Finally, the DNA strand breakage elongation assay showed that Tpo inhibits apoptosis of Lin-Sca-1+ bone marrow cells. Thus, Tpo has a potent ability to promote the viability and suppress apoptosis of primitive multipotent progenitor cells.

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Influence of albuterol on erythropoietin production and erythroid progenitor cell activation

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1979.236.3.h422 ◽

1979 ◽

Vol 236 (3) ◽

pp. H422-H426 ◽

Cited By ~ 1

Author(s):

F. Przala ◽

D. M. Gross ◽

B. Beckman ◽

J. W. Fisher

Keyword(s):

Bone Marrow ◽

Progenitor Cell ◽

Cell Activation ◽

Plasma Clot ◽

Erythroid Progenitor ◽

Erythroid Progenitor Cell ◽

Adrenergic Blocker ◽

Rabbit Bone

The effect of albuterol, a potent beta2-adrenergic agonist, on kidney production of erythropoietin (Ep) was studied. Its effects on erythroid colony (CFU-E) formation in vitro in rabbit bone marrow cultures were also assessed. Albuterol produced a significant increase in plasma Ep levels in conscious rabbits following 7 h intravenous infusion (50 (microgram/kg)/min). This effect was blocked by pretreatment of the rabbits with butoxamine (5 mg/kg ip), a potent beta2-adrenergic blocker. Albuterol in doses of 10(-10) to 10(-8) M in combination with Ep was also found to produce a significant increase in the numbers of CFU-E in the plasma clot culture system of rabbit bone marrow. This effect was blocked completely by DL-propranolol (10(-8) M) and by butoxamine (10(-8) M). The data presented suggest that albuterol, a potent activator of beta2-adrenergic receptors, increases kidney production of Ep in vivo and also produces a direct effect in combination with Ep on the proliferation of the erythroid progenitor cell compartment.

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Two classes of murine granulocyte progenitor cells expressed in plasma clot diffusion chamber cultures

Blood ◽

10.1182/blood.v59.4.838.838 ◽

1982 ◽

Vol 59 (4) ◽

pp. 838-843 ◽

Cited By ~ 6

Author(s):

HN Steinberg ◽

PL Page ◽

SH Robinson

Keyword(s):

Bone Marrow ◽

Progenitor Cells ◽

Cytosine Arabinoside ◽

Diffusion Chamber ◽

Velocity Sedimentation ◽

Mouse Bone Marrow ◽

Plasma Clot ◽

Residual Concentration

Abstract Two distinct classes of granulocyte progenitor cells present in normal mouse bone marrow are expressed sequentially in the vivo plasma clot diffusion chamber culture system. By several criteria, progenitor cells giving rise to granulocyte colonies on day 4 of culture (CFU-D4) are different from those giving rise to colonies on day 7 (CFU-D7). These differences include: cell cycle activity as measured by in vitro incubation with cytosine arabinoside, residual concentration in the bone marrow after in vivo treatment of donor mice with cytosine arabinoside or methotrexate, resistance to osmotic lysis, size as determined by velocity sedimentation, and the morphology of the granulocyte colonies to which these cells give rise. The CFU-D7 appears to represent an earlier progenitor cell than the CFU-D4 in the differentiation pathway of the granulocyte and is analagous in many respects to the BFU-E in the erythroid pathway.

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