The ability of bone marrow progenitor cells to form colonies in ex vivo culture of MDS patients

The results of in vitro hematopoiesis studies have provided most of the knowledge about the organization, regulation, and development of the human hematopoietic system over the past three to four decades. However, due to the impossibility of an appropriate assessment of hematopoietic stem cells (HSC) in humans and because of the shortcomings of methodological approaches to determining the role of hematopoietic progenitor cells in the pathogenesis of MDS and to predicting the course of the pathological process, semiliquid agar cultures of bone marrow from patients with myelodysplastic syndrome were used. Myelodysplastic syndrome (MDS) refers to a clinically, morphologically, and genetically heterogeneous group of diseases characterized by clonalism and arising from mutations at the level of hematopoietic progenitor cells. Proliferation of such a mutated stem cell progenitors leads to ineffective maturation of myeloid lineage cells and dysplastic changes in the bone marrow (BM). The aim of the study was to establish the relationship between the functional activity of hematopoietic progenitor cells in the ex vivo culture and the activity of the pathological process in the myelodysplastic syndrome. We studied bone marrow samples from patients with the myelodysplastic syndrome, namely refractory anemia with excess blasts I (MDS RAEB I) and refractory anemia with excess blasts II (MDS RAEB II) and AML under conditions in vitro, as well as their clinical laboratory data. It was found that the percentage of blasts and myeloblasts in the samples of patients with AML and MDS RAEB II increased, compared to the samples of patients with MDS RAEB I (63.5±3.9 %, 18.05±1.01 % and 9.49±1.53 % respectively). An increase in the number of erythrocytes and hemoglobin content was noted in the group of patients with MDS RAEB I compared with MDS RAEB II (2.9±1.4×1012 / l and 105.04±3.6 g / l versus 9±0.8×1012 / l and 84.5±4.8 g / l, respectively). The analysis of the results of BM studies of patients with MDS in in vitro culture indicated a significant lag in the formation of cell aggregates during cultivation and a pronounced inhibition of the colony-forming ability of progenitor cells, compared to the control. A noticeable decrease in the colony-forming ability was observed in patients with MDS RAEB I, MDS RAEB II and AML in this sequence – 4.1±1.2 per 1×105 explanted cells, 3.2±0.9 per 1×105 explanted cells and 2.0±0.6 per 1×105 explanted cells, respectively. The analysis of hematological parameters and the results of BM cells cultivation at different stages of MDS indicates that the colony-forming ability of progenitor cells correlates with the depth of the pathological process.

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Chemotactic and chemokinetic activities of stem cell factor on murine hematopoietic progenitor cells

Blood ◽

10.1182/blood.v87.10.4100.bloodjournal87104100 ◽

1996 ◽

Vol 87 (10) ◽

pp. 4100-4108 ◽

Cited By ~ 61

Author(s):

N Okumura ◽

K Tsuji ◽

Y Ebihara ◽

I Tanaka ◽

N Sawai ◽

...

Keyword(s):

Bone Marrow ◽

Stem Cell ◽

Progenitor Cells ◽

Stromal Cells ◽

Stem Cell Factor ◽

Hematopoietic Progenitor Cells ◽

Hematopoietic Progenitor ◽

Murine Bone Marrow ◽

Checkerboard Assay

We investigated the effects of stem cell factor (SCF) on the migration of murine bone marrow hematopoietic progenitor cells (HPC) in vitro using a modification of the checkerboard assay. Chemotactic and chemokinetic activities of SCF on HPC were evaluated by the numbers of HPC migrated on positive and negative gradients of SCF, respectively. On both positive and negative gradients of SCF, HPC began to migrate after 4 hours incubation, and their numbers then increased time- dependently. These results indicated that SCF functions as a chemotactic and chemokinetic agent for HPC. Analysis of types of colonies derived from the migrated HPC showed that SCF had chemotactic and chemokinetic effects on all types of HPC. When migrating activities of other cytokines were examined, interleukin (IL)-3 and IL-11 also affected the migration of HPC, but the degrees of each effect were lower than that of SCF. The results of the present study demonstrated that SCF is one of the most potent chemotactic and chemokinetic factors for HPC and suggest that SCF may play an important role in the flow of HPC into bone marrow where stromal cells constitutively produce SCF.

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Long-term generation and expansion of human primitive hematopoietic progenitor cells in vitro

Blood ◽

10.1182/blood.v81.3.661.661 ◽

1993 ◽

Vol 81 (3) ◽

pp. 661-669 ◽

Cited By ~ 92

Author(s):

EF Srour ◽

JE Brandt ◽

RA Briddell ◽

S Grigsby ◽

T Leemhuis ◽

...

Keyword(s):

Bone Marrow ◽

Progenitor Cells ◽

Bone Marrow Cells ◽

Fold Increase ◽

Hematopoietic Progenitor Cells ◽

Proliferative Potential ◽

Hematopoietic Progenitor ◽

Hla Dr

Abstract Although sustained production of committed human hematopoietic progenitor cells in long-term bone marrow cultures (LTBMC) is well documented, evidence for the generation and expansion of human primitive hematopoietic progenitor cells (PHPC) in such cultures is lacking. For that purpose, we attempted to determine if the human high proliferative potential colony-forming cell (HPP-CFC), a primitive hematopoietic marrow progenitor cell, is capable of generation and expansion in vitro. To that effect, stromal cell-free LTBMC were initiated with CD34+ HLA-DR-CD15- rhodamine 123dull bone marrow cells and were maintained with repeated addition of c-kit ligand and a synthetic interleukin-3/granulocyte-macrophage colony-stimulating factor fusion protein. By day 21 of LTBMC, a greater than twofold increase in the number of assayable HPP-CFC was detected. Furthermore, the production of HPP-CFC in LTBMC continued for up to 4 weeks, resulting in a 5.5-fold increase in HPP-CFC numbers. Weekly phenotypic analyses of cells harvested from LTBMC showed that the number of CD34+ HLA-DR- cells increased from 10(4) on day 0 to 56 CD34+ HLA-DR- cells increased from 10(4) on day 0 to 56 x 10(4) by day 21. To examine further the nature of the in vitro HPP-CFC expansion, individual HPP- CFC colonies were serially cloned. Secondary cloning of individual, day 28 primary HPP-CFC indicated that 46% of these colonies formed an average of nine secondary colony-forming unit--granulocyte-macrophage (CFU-GM)--derived colonies, whereas 43% of primary HPP-CFC gave rise to between one and six secondary HPP-CFC colonies and 6 to 26 CFU-GM. These data show that CD34+ HLA-DR- CD15- rhodamine 123dull cells represent a fraction of human bone marrow highly enriched for HPP-CFC and that based on their regeneration and proliferative capacities, a hierarchy of HPP-CFC exists. Furthermore, these studies indicate that in the presence of appropriate cytokine stimulation, it is possible to expand the number of PHPC in vitro.

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Flt3 Ligand Negatively Regulates In Vitro Migration, Intracellular Signaling Activated by SDF-1α/CXCR4 and In Vivo Homing of Hematopoietic Progenitor Cells.

Blood ◽

10.1182/blood.v104.11.2674.2674 ◽

2004 ◽

Vol 104 (11) ◽

pp. 2674-2674

Author(s):

Seiji Fukuda ◽

Hal E. Broxmeyer ◽

Louis M. Pelus

Keyword(s):

Bone Marrow ◽

Progenitor Cells ◽

Hematopoietic Progenitor Cells ◽

Leukemia Cells ◽

Flt3 Ligand ◽

Hematopoietic Progenitor ◽

Short Term ◽

Hematopoietic Stem

Abstract The Flt3 receptor tyrosine kinase (Flt3) is expressed on primitive normal and transformed hematopoietic cells and Flt3 ligand (FL) facilitates hematopoietic stem cell mobilization in vivo. The CXC chemokine SDF-1α(CXCL12) attracts primitive hematopoietic cells to the bone marrow microenvironment while disruption of interaction between SDF-1α and its receptor CXCR4 within bone marrow may facilitate their mobilization to the peripheral circulation. We have previously shown that Flt3 ligand has chemokinetic activity and synergistically increases migration of CD34+ cells and Ba/F3-Flt3 cells to SDF-1α in short-term migration assays; this was associated with synergistic phosphorylation of MAPKp42/p44, CREB and Akt. Consistent with these findings, over-expression of constitutively active ITD (internal tandem duplication) Flt3 found in patients with AML dramatically increased migration to SDF-1α in Ba/F3 cells. Since FL can induce mobilization of hematopoietic stem cells, we examined if FL could antagonize SDF-1α/CXCR4 function and evaluated the effect of FL on in vivo homing of normal hematopoietic progenitor cells. FL synergistically increased migration of human RS4;11 acute leukemia cells, which co-express wild-type Flt3 and CXCR4, to SDF-1α in short term migration assay. Exogenous FL had no effect on SDF-1α induced migration of MV4-11 cells that express ITD-Flt3 and CXCR4 however migration to SDF-1α was partially blocked by treatment with the tyrosine kinase inhibitor AG1296, which inhibits Flt3 kinase activity. These results suggest that FL/Flt3 signaling positively regulates SDF-1α mediated chemotaxis of human acute leukemia cells in short-term assays in vitro, similar to that seen with normal CD34+ cells. In contrast to the enhancing effect of FL on SDF-1α, prolonged incubation of RS4;11 and THP-1 acute myeloid leukemia cells, which also express Flt3 and CXCR4, with FL for 48hr, significantly inhibited migration to SDF-1α, coincident with reduction of cell surface CXCR4. Similarly, prolonged exposure of CD34+ or Ba/F3-Flt3 cells to FL down-regulates CXCR4 expression, inhibits SDF-1α-mediated phosphorylation of MAPKp42/p44, CREB and Akt and impairs migration to SDF-1α. Despite reduction of surface CXCR4, CXCR4 mRNA and intracellular CXCR4 in Ba/F3-Flt3 cells were equivalent in cells incubated with or without FL, determined by RT-PCR and flow cytometry after cell permeabilization, suggesting that the reduction of cell surface CXCR4 expression is due to accelerated internalization of CXCR4. Furthermore, incubation of Ba/F3-Flt3 cells with FL for 48hr or over-expression of ITD-Flt3 in Ba/F3 cells significantly reduced adhesion to VCAM1. Consistent with the negative effect of FL on in vitro migration and adhesion to VCAM1, pretreatment of mouse bone marrow cells with 100ng/ml of FL decreased in vivo homing of CFU-GM to recipient marrow by 36±7% (P<0.01), indicating that FL can negatively regulate in vivo homing of hematopoietic progenitor cells. These findings indicate that short term effect of FL can provide stimulatory signals whereas prolonged exposure has negative effects on SDF-1α/CXCR4-mediated signaling and migration and suggest that the FL/Flt3 axis regulates hematopoietic cell trafficking in vivo. Manipulation of SDF-1α/CXCR4 and FL/Flt3 interaction could be clinically useful for hematopoietic cell transplantation and for treatment of hematopoietic malignancies in which both Flt3 and CXCR4 are expressed.

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FDA-Approved Pharmacological Agents, Romiplostium and Oprelvekin, Synergistically Promote Megakaryocytic Differentiation From Human iPSCs In a Chemically Defined System

Blood ◽

10.1182/blood.v122.21.1208.1208 ◽

2013 ◽

Vol 122 (21) ◽

pp. 1208-1208

Author(s):

Yanfeng Liu ◽

Yongxing Gao ◽

Sid Shah ◽

Lewis Becker ◽

Linzhao Cheng ◽

...

Keyword(s):

Bone Marrow ◽

Progenitor Cells ◽

Embryoid Bodies ◽

Hematopoietic Progenitor Cells ◽

Patient Specific ◽

Hematopoietic Progenitor ◽

Free System ◽

Serum Free ◽

Megakaryocytic Differentiation

Abstract Platelets, anucleate cells derived from megakaryocytes (MKs) that are generated within the bone marrow, play an important role in the process of physiological hemostasis and in vascular repair. Low platelets in the blood stream result in bleeding risk in thrombocytopenic patients with liver failure, leukemia, or undergoing chemotherapy. Platelet transfusions remain the mainstay of treatment and require a constant supply of platelets. Because platelets from donor blood have a short life-span (only few days in storage), platelets are always in a short supply. In vitro generation of MKs and platelets from human induced pluripotent stem cells (hiPSCs) would provide a patient-specific renewable cell source of MKs and platelets to treat thrombocytopenic patients at risk of hemorrhage. We derived integration-free hiPSCs from peripheral blood cells of more than 20 individuals, and examined two methods of in vitro differentiation into MKs: i) co-culture on 10T1/2 cells or OP9 cells first developed by Takayama et al. (2010), and ii) a feeder-free and serum-free system by first forming embryoid bodies (EBs) in a chemically defined condition, similar to the recently published method of Pick et al. (2013). Although both methods gave rise with similar efficiency to CD41a+CD42a+ MKs with large cell size and high-ploidy DNA, we chose to focus on the feeder-free system that began with EB formation with centrifugal aggregation of hiPSCs (spin-EBs) because it is cheaper, faster, easier to scale up, and represents a chemically defined system. To investigate the effect of growth factors on hiPSC differentiation to MKs, we modified the spin-EB system to three steps: i) mesoderm induction and hematopoietic commitment in the presence of BMP4, VEGF, bFGF and SCF (day 0 to day 11), ii) hematopoietic progenitor and MK differentiation by adding TPO (day 11 to 14), and iii) MK maturation (day 14 to 19). To assess whether the FDA-approved pharmacological agent, Romiplostium (Nplate®, TPO analog), has a similar effect to TPO on MK differentiation from hiPSCs, we isolated hematopoietic progenitor cells at day 14, and differentiated them into MKs with Romiplostium or TPO. Our data demonstrated that Romiplostium (50 ng/ml) gave a 3-fold increase of CD41a+CD42a+ MKs, with similar dose-dependent kinetics as TPO. IL-11 has also been reported to enhance MK development. To test whether FDA-approved pharmacological IL-11, Oprelvekin (Neumega®), further stimulated MK differentiation from hiPSCs, we cultured hematopoietic progenitor cells from day 14 in the presence of Romiplostium and Oprelvekin for 5 days. Our data showed that Romiplostium and Oprelvekin synergistically promote megakaryocytic differentiation. In the presence of Romiplostium, 60 to 95 % of cells were CD41a+CD42a+ MKs. Addition of Oprelvekin significantly increased the number of CD41a+CD42a+ MKs, but not the percentage of CD41a+CD42a+ MKs, suggesting that Oprelvekin enhanced a proliferation of MK progenitors. So far, 10 hiPSC lines from several individuals have been tested using the combination of Romiplostium and Oprelvekin in the feeder-free and serum-free differentiation condition. We are currently investigating if the MKs and platelets generated by this defined and scalable system are as fully functional as those generated from bone marrow CD34+ cells from healthy donors. * The first three authors contributed equally; This study is supported in part by an NIH grant U01 HL-107446 and 2012-MSCRFII-0124 (to ZZ Wang). Disclosures: No relevant conflicts of interest to declare.

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Murine Hematopoietic Progenitor Cells With Colony-Forming or Radioprotective Capacity Lack Expression of the β2-Integrin LFA-1

Blood ◽

10.1182/blood.v93.1.107.401k14_107_112 ◽

1999 ◽

Vol 93 (1) ◽

pp. 107-112 ◽

Cited By ~ 2

Author(s):

Johannes F.M. Pruijt ◽

Yvette van Kooyk ◽

Carl G. Figdor ◽

Roel Willemze ◽

Willem E. Fibbe

Keyword(s):

Bone Marrow ◽

Steady State ◽

Progenitor Cells ◽

Mononuclear Cells ◽

Hematopoietic Progenitor Cells ◽

Colony Stimulating Factor ◽

Hematopoietic Progenitor ◽

Β2 Integrin ◽

Stimulating Factor

Recently, we have demonstrated that antibodies that block the function of the β2-integrin leukocyte function-associated antigen-1 (LFA-1) completely abrogate the rapid mobilization of hematopoietic progenitor cells (HPC) with colony-forming and radioprotective capacity induced by interleukin-8 (IL-8) in mice. These findings suggested a direct inhibitory effect of these antibodies on LFA-1–mediated transmigration of stem cells through the bone marrow endothelium. Therefore, we studied the expression and functional role of LFA-1 on murine HPC in vitro and in vivo. In steady state bone marrow ± 50% of the mononuclear cells (MNC) were LFA-1neg. Cultures of sorted cells, supplemented with granulocyte colony-stimulating factor (G-CSF)/granulocyte-macrophage colony-stimulating factor (GM-CSF)/IL-1/IL-3/IL-6/stem cell factor (SCF) and erythropoietin (EPO) indicated that the LFA-1neg fraction contained the majority of the colony-forming cells (CFCs) (LFA-1neg 183 ± 62/7,500 cells v LFA-1pos 29 ± 17/7,500 cells,P < .001). We found that the radioprotective capacity resided almost exclusively in the LFA-1neg cell fraction, the radioprotection rate after transplantation of 103, 3 × 103, 104, and 3 × 104 cells being 63%, 90%, 100%, and 100% respectively. Hardly any radioprotection was obtained from LFA-1pos cells. Similarly, in cytokine (IL-8 and G-CSF)–mobilized blood, the LFA-1neg fraction, which comprised 5% to 10% of the MNC, contained the majority of the colony-forming cells, as well as almost all cells with radioprotective capacity. Subsequently, primitive bone marrow-derived HPC, represented by Wheat-germ-agglutinin (WGA)+/Lineage (Lin)−/Rhodamine (Rho)− sorted cells, were examined. More than 95% of the Rho− cells were LFA-1neg. Cultures of sorted cells showed that the LFA-1neg fraction contained all CFU. Transplantation of 150 Rho− LFA-1neg or up to 600 Rho−LFA-1pos cells protected 100% and 0% of lethally irradiated recipient mice, respectively. These results show that primitive murine HPC in steady-state bone marrow and of cytokine-mobilized blood do not express LFA-1.

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The Sialomucin CD164 (MGC-24v) Is an Adhesive Glycoprotein Expressed by Human Hematopoietic Progenitors and Bone Marrow Stromal Cells That Serves as a Potent Negative Regulator of Hematopoiesis

Blood ◽

10.1182/blood.v92.8.2613.420k15_2613_2628 ◽

1998 ◽

Vol 92 (8) ◽

pp. 2613-2628 ◽

Cited By ~ 1

Author(s):

Andrew C.W. Zannettino ◽

Hans-Jörg Bühring ◽

Silvana Niutta ◽

Suzanne M. Watt ◽

M. Ann Benton ◽

...

Keyword(s):

Bone Marrow ◽

Cell Surface ◽

Progenitor Cells ◽

Stromal Cells ◽

Functional Characterization ◽

Negative Regulator ◽

Hematopoietic Progenitor Cells ◽

Expression Cloning ◽

Hematopoietic Progenitor

Mucin-like molecules represent an emerging family of cell surface glycoproteins expressed by cells of the hematopoietic system. We report the isolation of a cDNA clone that encodes a novel transmembrane isoform of the mucin-like glycoprotein MGC-24, expressed by both hematopoietic progenitor cells and elements of the bone marrow (BM) stroma. This molecule was clustered as CD164 at the recent workshop on human leukocyte differentiation antigens. CD164 was identified using a retroviral expression cloning strategy and two novel monoclonal antibody (MoAb) reagents, 103B2/9E10 and 105.A5. Both antibodies detected CD164/MGC-24v protein expression by BM stroma and subpopulations of the CD34+ cells, which include the majority of clonogenic myeloid (colony-forming unit–granulocyte-macrophage [CFU-GM]) and erythroid (blast-forming unit-erythroid [BFU-E]) progenitors and the hierarchically more primitive precursors (pre-CFU). Biochemical and functional characterization of CD164 showed that this protein represents a homodimeric molecule of approximately 160 kD. Functional studies demonstrate a role for CD164 in the adhesion of hematopoietic progenitor cells to BM stromal cells in vitro. Moreover, antibody ligation of CD164 on primitive hematopoietic progenitor cells characterized by the cell surface phenotype CD34BRIGHTCD38− results in the decreased recruitment of these cells into cell cycle, suggesting that CD164 represents a potent signaling molecule with the capacity to suppress hematopoietic cell proliferation. © 1998 by The American Society of Hematology.

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Evaluation of ex vivo expansion potential of cord blood and bone marrow hematopoietic progenitor cells using cell tracking and limiting dilution analysis

Blood ◽

10.1182/blood.v85.8.2059.bloodjournal8582059 ◽

1995 ◽

Vol 85 (8) ◽

pp. 2059-2068 ◽

Cited By ~ 115

Author(s):

CM Traycoff ◽

ST Kosak ◽

S Grigsby ◽

EF Srour

Keyword(s):

Bone Marrow ◽

Cord Blood ◽

Progenitor Cells ◽

Cell Tracking ◽

Ex Vivo ◽

Hematopoietic Progenitor Cells ◽

Hematopoietic Progenitor ◽

Cells In Culture ◽

Cd34 Cells ◽

Limiting Dilution

In the absence of conclusive assays capable of determining the functionality of ex vivo expanded human hematopoietic progenitor cells, we combined cell tracking with the membrane dye PKH2, immunostaining for CD34, and limiting dilution analysis to estimate the frequency of long-term hematopoietic culture-initiating cells (LTHC-ICs) among de novo-generated CD34+ cells. Umbilical cord blood (CB) and bone marrow (BM) CD34+ cells were stained with PKH2 on day 0 and cultured with stem cell factor (SCF) and interleukin-3 (IL-3) in short-term stromal cell-free suspension cultures. Proliferation of CD34+ cells in culture was tracked through their PKH2 fluorescence relative to day 0 and the continued expression of CD34. As such, it was possible to identify cells that had divided while maintaining the expression of CD34 (CD34+PKH2dim) and others that expressed CD34 but had not divided (CD34+PKH2bright). In all such cultures, a fraction of both BM and CB CD34+ cells failed to divide in response to cytokines and persisted in culture for up to 10 days as CD34+PKH2bright cells. Between days 5 and 7 of culture, CD34+PKH2bright and CD34+PKH2dim cells were sorted in a limiting dilution scheme into 96-well plates prepared with medium, SCF, IL-3, IL-6, granulocyte-macrophage colony-stimulating factor, and erythropoietin. Cells proliferating in individual wells were assayed 2 weeks later for their content of clonogenic progenitors and the percentage of negative wells was used to calculate the frequency of LTHC-ICs in each population. Among fresh isolated BM and CB CD34+ cells, the frequencies of LTHC-ICs were 2.01% +/- 0.98% (mean +/- SEM) and 7.56% +/- 2.48%, respectively. After 5 to 7 days in culture, 3.00% +/- 0.56% of ex vivo-expanded BM CD34+PKH2bright cells and 4.46% +/- 1.10% of CD34+PKH2dim cells were LTHC-ICs. In contrast, the frequency of LTHC-IC in ex vivo expanded CB CD34+ cells declined drastically, such that only 3.87% +/- 2.06% of PKH2bright and 2.29% +/- 1.75% of PKH2dim cells were determined to be initiating cells after 5 to 7 days in culture. However, when combined with a calculation of the net change in the number of CD34+ cells in culture, the sum total of LTHC-ICs in both BM and CB cells declined in comparison to fresh isolated cells, albeit to a different degree between the two tissues.(ABSTRACT TRUNCATED AT 400 WORDS)

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Evidence for nonclonal hematopoietic progenitor cell populations in bone marrow of patients with myelodysplastic syndromes

Blood ◽

10.1182/blood.v84.2.588.588 ◽

1994 ◽

Vol 84 (2) ◽

pp. 588-594 ◽

Cited By ~ 34

Author(s):

H Asano ◽

H Ohashi ◽

M Ichihara ◽

T Kinoshita ◽

T Murate ◽

...

Keyword(s):

Bone Marrow ◽

Progenitor Cells ◽

X Chromosome ◽

Myelodysplastic Syndromes ◽

Hematopoietic Progenitor Cells ◽

Refractory Anemia ◽

Hematopoietic Progenitor Cell ◽

Colony Stimulating Factor ◽

Hematopoietic Progenitor ◽

Stimulating Factor

Abstract Clonality of marrow hematopoietic progenitor cells in myelodysplastic syndromes (MDS) was analyzed by X-chromosome inactivation pattern using polymerase chain reaction (PCR). Five female patients were included in this study; two with refractory anemia (RA) and three with RA with excess blasts (RAEB). They were heterozygous for BstXI restriction fragment length polymorphisms (RFLP) of the X-chromosome-linked phosphoglycerate kinase (PGK) gene. In each patient, erythroid and nonerythroid colonies, grown in the presence of erythropoietin and granulocyte-macrophage colony-stimulating factor (GM-CSF), exhibited no remarkable difference in clonal constitution. Two patients showed only one methylation pattern, suggesting the monoclonal origin of hematopoietic progenitor cells. Colonies of two other patients exhibited predominant and minor methylation patterns in PGK gene, indicating that nonclonal progenitor cells remain a minor population. The bone marrow of one patient appeared to contain a greater proportion of nonclonal progenitors. Stem cell factor (SCF), a potent colony- stimulating factor, enhanced both erythroid and nonerythroid colony formation. However, it did not notably alter the clonal constitutions. We conclude that nonclonal hematopoietic progenitor cells can persist in a substantial number of MDS patients.

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Murine Hematopoietic Progenitor Cells With Colony-Forming or Radioprotective Capacity Lack Expression of the β2-Integrin LFA-1

Blood ◽

10.1182/blood.v93.1.107 ◽

1999 ◽

Vol 93 (1) ◽

pp. 107-112 ◽

Cited By ~ 29

Author(s):

Johannes F.M. Pruijt ◽

Yvette van Kooyk ◽

Carl G. Figdor ◽

Roel Willemze ◽

Willem E. Fibbe

Keyword(s):

Bone Marrow ◽

Steady State ◽

Progenitor Cells ◽

Mononuclear Cells ◽

Hematopoietic Progenitor Cells ◽

Colony Stimulating Factor ◽

Hematopoietic Progenitor ◽

Β2 Integrin ◽

Stimulating Factor

Abstract Recently, we have demonstrated that antibodies that block the function of the β2-integrin leukocyte function-associated antigen-1 (LFA-1) completely abrogate the rapid mobilization of hematopoietic progenitor cells (HPC) with colony-forming and radioprotective capacity induced by interleukin-8 (IL-8) in mice. These findings suggested a direct inhibitory effect of these antibodies on LFA-1–mediated transmigration of stem cells through the bone marrow endothelium. Therefore, we studied the expression and functional role of LFA-1 on murine HPC in vitro and in vivo. In steady state bone marrow ± 50% of the mononuclear cells (MNC) were LFA-1neg. Cultures of sorted cells, supplemented with granulocyte colony-stimulating factor (G-CSF)/granulocyte-macrophage colony-stimulating factor (GM-CSF)/IL-1/IL-3/IL-6/stem cell factor (SCF) and erythropoietin (EPO) indicated that the LFA-1neg fraction contained the majority of the colony-forming cells (CFCs) (LFA-1neg 183 ± 62/7,500 cells v LFA-1pos 29 ± 17/7,500 cells,P < .001). We found that the radioprotective capacity resided almost exclusively in the LFA-1neg cell fraction, the radioprotection rate after transplantation of 103, 3 × 103, 104, and 3 × 104 cells being 63%, 90%, 100%, and 100% respectively. Hardly any radioprotection was obtained from LFA-1pos cells. Similarly, in cytokine (IL-8 and G-CSF)–mobilized blood, the LFA-1neg fraction, which comprised 5% to 10% of the MNC, contained the majority of the colony-forming cells, as well as almost all cells with radioprotective capacity. Subsequently, primitive bone marrow-derived HPC, represented by Wheat-germ-agglutinin (WGA)+/Lineage (Lin)−/Rhodamine (Rho)− sorted cells, were examined. More than 95% of the Rho− cells were LFA-1neg. Cultures of sorted cells showed that the LFA-1neg fraction contained all CFU. Transplantation of 150 Rho− LFA-1neg or up to 600 Rho−LFA-1pos cells protected 100% and 0% of lethally irradiated recipient mice, respectively. These results show that primitive murine HPC in steady-state bone marrow and of cytokine-mobilized blood do not express LFA-1.

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Colony growth of human hematopoietic progenitor cells in the absence of serum is supported by a proteinase inhibitor identified as antileukoproteinase.

Journal of Experimental Medicine ◽

10.1084/jem.184.4.1305 ◽

1996 ◽

Vol 184 (4) ◽

pp. 1305-1312 ◽

Cited By ~ 12

Author(s):

H M Goselink ◽

J van Damme ◽

P S Hiemstra ◽

A Wuyts ◽

J Stolk ◽

...

Keyword(s):

Bone Marrow ◽

Growth Factors ◽

Progenitor Cells ◽

Conditioned Medium ◽

Proteinase Inhibitor ◽

Hematopoietic Progenitor Cells ◽

Hematopoietic Progenitor ◽

Serum Free ◽

Accessory Cells

Serum contains many growth factors and nutrients that stimulate colony formation of hematopoietic progenitor cells (HPC) in semisolid cultures. In the absence of serum, no proliferation of HPCs could be obtained in semisolid medium cultures of partially purified bone marrow cells in the presence of multiple hematopoietic growth factors, insulin, cholesterol, and purified clinical-grade human albumin. This appeared to be due to a suppressive activity induced by monocyte- and T lymphocyte-depleted accessory cells on CD34+ HPCs. Serum-free conditioned medium from the bladder carcinoma cellline 5637 could replace serum to support the growth of HPCs in these cultures. After gel filtration and reverse-phase high-performance liquid chromatography of 5637 supernatants, this activity could be attributed to a 15-kD protein that was further identified by NH2-terminal sequence analysis as the serine proteinase inhibitor antileukoproteinase (ALP). The growth-supportive activity from the 5637 conditioned medium and the (partially) purified fractions could be completely neutralized by a polyclonal rabbit IgG antibody against human ALP (huALP). Similar supportive effects on the growth of HPC could be obtained in the presence of recombinant huALP. We demonstrated that the COOH-terminal domain of ALP containing the proteinase inhibitory activity was responsible for this effect. alpha-1 proteinase inhibitor was capable of similar support of in vitro HPC growth. These results illustrate that proteinase inhibitors play an important role in the in vitro growth of hematopoietic cells by the neutralization of proteinases produced by bone marrow accessory cells. This may be of particular relevance for in vitro expansion of human hematopoietic stem cells in serum-free media.

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