scholarly journals HOXB4 Enforces Equivalent Fates of ES-Cell-Derived and Adult Hematopoietic Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 494-494 ◽  
Author(s):  
Sandra Pilat ◽  
Carotta Sebastian ◽  
Schiedlmeier Bernhard ◽  
Modlich Ute ◽  
Kamino Kenji ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Bone Marrow ◽  
Bone Marrow Cells ◽  
Es Cells ◽  
Es Cell ◽  
Somatic Gene Therapy ◽  
Adult Bone Marrow ◽  
Somatic Gene ◽  
Adult Bone

Abstract In the context of somatic gene therapy of the hematopoietic system, transplantation of molecularly defined and, hence, “safe” clones would be highly desirable. However, techniques which allow gene targeting, subsequent <i>in vitro</i> selection and clonal expansion are only available for embryonic stem (ES−) cells. Previously, it has been shown that <i>in vitro</i> differentiated ES-cells engraft when ectopically expressing HOXB4, but it remained unclear whether these cells could fully resemble adult bone marrow function after transplantation<sup>1</sup>. We here demonstrate for the first time the functional equivalence of <i>in vitro</i> differentiated ES-cells and adult bone marrow cells mediated by HOXB4. Differentiated ES-cells expressing HOXB4 from a retroviral vector and grown <i>in vitro</i> for 20 days, recapitulated the growth and differentiation properties of adult bone marrow cells after transplantation into Rag2<sup>(−/−)</sup>γC<sup>(−/−)</sup> and C57Bl/6J recipient mice. Furthermore, we show that the amount of ectopically expressed HOXB4 influences differentiation in both systems in a similar manner. HOXB4 enforced myeloid and suppressed T-lymphoid development over a wide range of expression levels, whereas only high expression levels of HOXB4 were detrimental for erythroid development (P-values for C57Bl/6J mice, Student’s t-test, 2-sided: CD3 + : eGFP<sup>low</sup> vs. HOX<sup>low</sup> = 0.003; eGFP<sup>high</sup> vs. HOX<sup>high</sup> = 0.021; Ter119 +: eGFP<sup>low</sup> vs. HOX<sup>low</sup> = 0.920; eGFP<sup>high</sup> vs. HOX<sup>high</sup> = 0.0122; HOX<sup>low</sup> vs. HOX<sup>high</sup> = 0.005). Incompatibility of high levels of HOXB4 expression with erythroid differentiation was also directly demonstrated using a recently described <i>in vitro</i> ES-cell differentiation system<sup>2</sup>. Histological analysis of the “HOXB4-transplanted” mice revealed increased granulopoiesis both in sternal bone marrow and in spleen sections. However, all stages of granulocytic differentiation were present and neither were immature cells detected in the periphery nor was leukemic infiltration detected in other organs. Hence, none of the animals became leukemic during the observation period. In summary, ES-cells should be considered a promising alternative to bone marrow stem cells carrying the potential of safe somatic gene therapy, provided that human ES-cells can be similarly manipulated. Nonetheless, advanced cell therapy will certainly require regulated expression of HOXB4 to avoid unwanted effects such as disturbed lineage differentiation. This work was supported by the German Research Foundation (KL1311/2-3 and 2-4), German Cancer Aid (10-1763-OS5) and the Austrian Industrial Research Promotion Fund (808714).

Hematopoietic Repopulation, In Vivo, with Genetically Defined Clones Derived from HOXB4 Expressing ES-Cells.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 196-196
Author(s):  
Sandra Pilat ◽  
Sebastian Carotta ◽  
Bernhard Schiedlmeier ◽  
Kenji Kamino ◽  
Andreas Mairhofer ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Bone Marrow ◽  
Es Cells ◽  
Es Cell ◽  
Somatic Gene Therapy ◽  
Hematopoietic System ◽  
Somatic Gene

Abstract In the context of somatic gene therapy of the hematopoietic system, transplantation of molecularly defined and, hence, “safe” clones would be highly desirable. However, techniques which allow gene targeting, subsequent in vitro selection and clonal expansion are only available for embryonic stem (ES) cells. After in vitro differentiation, some of their progeny cells are capable of mediating long term hematopoietic repopulation after transplantation into immunodeficient recipient mice, in vivo. This is especially efficient when the homeodomain transcription factor HOXB4 is ectopically expressed (1). We have recently shown that HOXB4-ES-cell derivatives behave similar to bone marrow cells also expressing this transcription factor ectopically, both in vitro and in vivo (2). Here we demonstrate that long term repopulation (>6 months) in Rag2(−/−)γ C(−/−) mice can be achieved with ES-cell derived hematopoietic cells (ES-HCs) obtained from single, molecularly characterized ES-clones, in which the insertion sites of the retroviral expression vector had been defined. Clones expressing HOXB4 above a certain level showed a high extent of chimerism in the bone marrow of transplanted mice (average 75%; range 45–95%, n=4) whereas ES-HC clones expressing lower levels only repopulated with very low efficiency (average 2.5% chimerism, range 1–4%, n=6 mice). These results suggest that the capability of long-term repopulation, in vivo, is highly dependent on the expression levels of HOXB4 in the transplanted clones. Only mice reconstituted with ES-HC clones expressing high amounts of HOXB4 and thus showing substantial chimerism, recapitulated the morphohistological phenotype observed in polyclonally reconstituted mice. This included the bias towards myelopoiesis, “benign” myeloid proliferation in spleen and the incompatibility of HOXB4 expression with T-cell poiesis (2). In summary, we demonstrate that repopulation of the hematopoietic system can be achieved with preselected clones of genetically manipulated stem cells in which a) the insertion site of the retroviral (gene therapy) vector has been characterized prior to transplantation and b) in which ectopic HOXB4 has to be expressed above a certain threshold level. Thus, ES cells carry the potential for performing safe somatic gene therapy when using integrating gene therapy vectors. Nevertheless, advanced cell therapy will certainly require the expression of HOXB4 in a regulated manner to avoid unwanted effects such as disturbed lineage differentiation.

scholarly journals In vitro tolerance induction of neonatal murine B cells as a probe for the study of B-cell diversification.

1977 ◽  
Vol 145 (5) ◽  
pp. 1382-1386 ◽  
Author(s):  
E S Metcalf ◽  
N H Sigal ◽  
N R Klinman
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
B Cell ◽  
Bone Marrow Cells ◽  
Tolerance Induction ◽  
Adult Bone Marrow ◽  
Late Expression ◽  
Adult Bone ◽  
Marrow Cells

The susceptibility to in vitro tolerance induction has been implicated as a characteristic of B cells early in their development, since DNP-reactive B cells are tolerizable only during the first days after birth, and 25% of adult bone marrow cells are tolerizable. In the present study, a modification of the in vitro splenic focus technique was utilized to determine if PC-specific B cells, by virtue of their late expression (approximately 1 wk post-parturition), also display susceptibility to tolerance induction. The results demonstrate that at 7-10 days after birth, when over 90% of the DNP-specific splenic B cells are resistant to tolerance induction, the majority of PC-specific B cells are tolerizable. These results re-emphasize tolerance susceptibility as a characteristic of developing clones, confirm the late acquisition of PC-specific B cells, and support the contention that the acquisition of the specificity repertoire is a highly ordered, specifically predetermined process which is independent of antigen-driven events.

scholarly journals Consistent activation of fetal hemoglobin synthesis in cultured adult bone marrow cells

Blood ◽  
1978 ◽  
Vol 51 (4) ◽  
pp. 671-679 ◽  
Author(s):  
T Papayannopoulou ◽  
PE Nute ◽  
S Kurachi ◽  
G Stamatoyannopoulos
Keyword(s):  
Bone Marrow ◽  
Cultured Cells ◽  
Bone Marrow Cells ◽  
Fetal Hemoglobin ◽  
Exchange Chromatography ◽  
Plasma Clot ◽  
Adult Bone Marrow ◽  
Adult Bone ◽  
Marrow Cells

The production of fetal hemoglobin was investigated in plasma clot cultures of adult bone marrow cells from normal donors and from individuals with homozygous HbS or HbC disease. Synthesis of gamma and beta chains was assessed either by 35S-methionine labeling of cultures and measurement of the radioactivity incorporated into the methionine- containing tryptic peptides of the gamma and beta subunits or by 3H- leucine labeling and measurement of the radioactivity incorporated into the globin chains of Hbs F0 and A0 isolated by ion-exchange chromatography. The cultures from all individuals responded with increased production of HbF. Cultured cells from subjects without a hemoglobinopathy produced an average of 8.2% gamma chains (range 3.1%– 20.3%), while cultured cells from subjects homozygous for HbS or HbC produced an average of 16.6% gamma chains (range 12.2%–20.4%). These findings indicate that fetal Hb production was regularly enhanced in adult bone marrow cells triggered in vitro to clonal growth in the plasma clot culture system.

scholarly journals Consistent activation of fetal hemoglobin synthesis in cultured adult bone marrow cells

Blood ◽  
1978 ◽  
Vol 51 (4) ◽  
pp. 671-679 ◽  
Author(s):  
T Papayannopoulou ◽  
PE Nute ◽  
S Kurachi ◽  
G Stamatoyannopoulos
Keyword(s):  
Bone Marrow ◽  
Cultured Cells ◽  
Bone Marrow Cells ◽  
Fetal Hemoglobin ◽  
Exchange Chromatography ◽  
Plasma Clot ◽  
Adult Bone Marrow ◽  
Adult Bone ◽  
Marrow Cells

Abstract The production of fetal hemoglobin was investigated in plasma clot cultures of adult bone marrow cells from normal donors and from individuals with homozygous HbS or HbC disease. Synthesis of gamma and beta chains was assessed either by 35S-methionine labeling of cultures and measurement of the radioactivity incorporated into the methionine- containing tryptic peptides of the gamma and beta subunits or by 3H- leucine labeling and measurement of the radioactivity incorporated into the globin chains of Hbs F0 and A0 isolated by ion-exchange chromatography. The cultures from all individuals responded with increased production of HbF. Cultured cells from subjects without a hemoglobinopathy produced an average of 8.2% gamma chains (range 3.1%– 20.3%), while cultured cells from subjects homozygous for HbS or HbC produced an average of 16.6% gamma chains (range 12.2%–20.4%). These findings indicate that fetal Hb production was regularly enhanced in adult bone marrow cells triggered in vitro to clonal growth in the plasma clot culture system.

scholarly journals The Translocation t(7;12)(q36;p13) Induces Myeloid Leukemia in Immuno-Compromised but Not Immunocompetent Mice

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2707-2707
Author(s):  
Ahmed Waraky ◽  
Anders Östlund ◽  
Laleh Arabanian ◽  
Tina Nilsson ◽  
Linda Fogelstrand ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Bone Marrow Cells ◽  
Fetal Liver ◽  
Liver Cells ◽  
Adult Bone Marrow ◽  
Leukemia Development ◽  
Fetal Liver Cells ◽  
Immunocompetent Mice ◽  
Adult Bone

Introduction: Non-random cytogenetic aberrations are often involved in the development of AML in children and several aberrations can serve as diagnostic markers, prognosis predictors and impact choice of therapy. In infant AML, a chromosomal translocation t(7;12)(q36;p13) has been found in up to 20-30 % of the cases, making it the second most common genetic aberration in this age group after KMT2A (MLL) rearrangements. Previous studies indicate that this patient group has a dismal prognosis with virtually no event-free survival. Limiting the chances to improve this is the lack of understanding how the t(7;12)(q36;p13) is involved in leukemia development. The translocation leads to a gene fusion MNX1-ETV6 but also to increased MNX1 gene expression. Although both ETV6 and MNX1 are expressed in normal hematopoietic tissues, the role of the fusion protein MNX1-ETV6in the development of AML is not established. Also unclear is whether the driver of leukemogenesis is the fusion itself or the simultaneous overexpression of MNX1. The aim of this study was to assess the transformation capacity and the molecular mechanism of the MNX1-ETV6 fusion and the overexpressed MNX1in vitro and in vivo using murine transplantation models. Material and methods: In a liquid culture system, we introduced the MNX1-ETV6 fusion, MNX1 overexpression, or empty vector into primary murine (C57BL/6) hematopoietic progenitor cells with retroviral transfection. Cells were isolated from either adult bone marrow after 5-FU stimulation, or from fetal liver at E14.5. After enrichment by fluorescence activated cell sorting based on vector co-expressed green/yellow fluorescence protein, transfected cells were used for in vitro experiments and for transplantation into lethally irradiated immunocompetent C57BL/6 mice or sub-lethally irradiated immunocompromised NSGW41 mice. In vitro, cells were assessed with RNA sequencing for gene expression, gamma H2AX assay for DNA double strand brakes, flow cytometry for lineage marker expression, apoptosis and proliferation, and with colony forming unit assay. Results: Upon transplantation, only fetal liver cells transduced with MNX1 or with MNX1-ETV6 fusion were able to induce leukemia in immunocompromised (NSGW41) mice. When MNX1 or MNX1-ETV6 transduced cells were transplanted into immunocompetent mice (C57BL/6) mice, no leukemia development was seen, when either fetal liver or adult bone marrow cells were used for transduction. However, when immunocompromised mice were transplanted with MNX1 or MNX1-ETV6 fusion expressing cells they typically developed signs of disease after 1-2 months and exhibited leukocytosis and elevated blast cells in blood and bone marrow, severe anemia, and enlarged spleens with infiltration of leukemic cells. The cells showed expression of predominantly myeloid markers. In vitro, cells with overexpression of MNX1 or MNX1-ETV6 fusion expression also showed altered lineage differentiation in favor of myeloid differentiation. In addition, MNX1 overexpressing cells, but not MNX1-ETV6 expressing cells, exhibited increased proliferation and colony formation capacity. Both MNX1 overexpressing and MNX1-ETV6 fusion expressing cells showed increased DNA damage as evident from an increased gamma-phosphorylated H2AX in fetal liver and adult bone marrow transduced cells respectively, accompanied with G1 arrest, compared to cells transduced with empty vectors. Both MNX1 and MNX1-ETV6 also led to increased apoptosis in adult bone marrow (3-fold) and to a lesser extent in fetal liver cells (1.5-fold). Results from transcriptome sequencing showed enrichment for specific pathways in G2/M transition of cell cycle in cells transduced by either MNX1or the MNX1-ETV6 fusion. Further investigations to elucidate the molecular mechanisms and pathways through which MNX1 and/or MNX1-ETV6 induce leukemia is ongoing. Conclusions: MNX1 overexpression and MNX1-ETV6 fusion, both characteristics of infant AML with t(7;12)(q36;p13), induced leukemogenic effects in both fetal liver cells and adult bone marrow cells, but could cause a myeloid leukemia only under immunocompromised conditions. This may be of importance for the exclusive prevalence of this AML subtype in young children, with the highest peak during the first six months of life when the immune system is less developed. Disclosures No relevant conflicts of interest to declare.

scholarly journals Human fetal liver MSCs are more effective than adult bone marrow MSCs for their immunosuppressive, immunomodulatory, and Foxp3+ T reg induction capacity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yi Yu ◽  
Alejandra Vargas Valderrama ◽  
Zhongchao Han ◽  
Georges Uzan ◽  
Sina Naserian ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Immune Responses ◽  
Molecular Mechanisms ◽  
Fetal Liver ◽  
Cytotoxic T Cells ◽  
Cell Contact ◽  
Adult Bone Marrow ◽  
Adult Bone

Abstract Background Mesenchymal stem cells (MSCs) exhibit active abilities to suppress or modulate deleterious immune responses by various molecular mechanisms. These cells are the subject of major translational efforts as cellular therapies for immune-related diseases and transplantations. Plenty of preclinical studies and clinical trials employing MSCs have shown promising safety and efficacy outcomes and also shed light on the modifications in the frequency and function of regulatory T cells (T regs). Nevertheless, the mechanisms underlying these observations are not well known. Direct cell contact, soluble factor production, and turning antigen-presenting cells into tolerogenic phenotypes, have been proposed to be among possible mechanisms by which MSCs produce an immunomodulatory environment for T reg expansion and activity. We and others demonstrated that adult bone marrow (BM)-MSCs suppress adaptive immune responses directly by inhibiting the proliferation of CD4+ helper and CD8+ cytotoxic T cells but also indirectly through the induction of T regs. In parallel, we demonstrated that fetal liver (FL)-MSCs demonstrates much longer-lasting immunomodulatory properties compared to BM-MSCs, by inhibiting directly the proliferation and activation of CD4+ and CD8+ T cells. Therefore, we investigated if FL-MSCs exert their strong immunosuppressive effect also indirectly through induction of T regs. Methods MSCs were obtained from FL and adult BM and characterized according to their surface antigen expression, their multilineage differentiation, and their proliferation potential. Using different in vitro combinations, we performed co-cultures of FL- or BM-MSCs and murine CD3+CD25−T cells to investigate immunosuppressive effects of MSCs on T cells and to quantify their capacity to induce functional T regs. Results We demonstrated that although both types of MSC display similar cell surface phenotypic profile and differentiation capacity, FL-MSCs have significantly higher proliferative capacity and ability to suppress both CD4+ and CD8+ murine T cell proliferation and to modulate them towards less active phenotypes than adult BM-MSCs. Moreover, their substantial suppressive effect was associated with an outstanding increase of functional CD4+CD25+Foxp3+ T regs compared to BM-MSCs. Conclusions These results highlight the immunosuppressive activity of FL-MSCs on T cells and show for the first time that one of the main immunoregulatory mechanisms of FL-MSCs passes through active and functional T reg induction.

Treatment of Inherited Neurometabolic Diseases: The Future

1992 ◽  
Vol 7 (1_suppl) ◽  
pp. S132-S140 ◽  
Author(s):  
Pinar T. Ozand ◽  
Generoso G. Gascon
Keyword(s):  
Gene Therapy ◽  
Bone Marrow ◽  
Autologous Bone Marrow ◽  
Marrow Transplant ◽  
Somatic Gene Therapy ◽  
Autologous Bone Marrow Transplant ◽  
Somatic Gene ◽  
Dividing Cells ◽  
Normal Gene ◽  
Religious Considerations

The past 10 years' experience with bone marrow transplantation from normal, immunologically compatible donors indicates its possible use in various neurometabolic diseases, particularly in a patient who has not suffered irreparable brain damage. This experience may be a prelude to treatment by somatic gene therapy. This can be applied as an autologous bone marrow transplant, grafting the patient's own stem cells inserted with the normal gene. Although somatic gene therapy will be relatively easy for tissues with dividing cells, its application to target tissues with little or no cell division may pose difficulties. Meanwhile, techniques for the preservation, culture, and grafting of fetal neurons in humans have been developed and have been used in the treatment of Parkinson's disease. These procedures could readily be transferred to the treatment of other neurodegenerative diseases that cause significant morbidity, but ethical, legal, and religious considerations must be taken into account. All these efforts promise novel and improved management of inborn neurometabolic errors. (J Child Neurol 1992;7(Suppl):S132-S140.)

scholarly journals The Characterization, Molecular Cloning, and Expression of a Novel Hematopoietic Cell Antigen From CD34+ Human Bone Marrow Cells

Blood ◽  
1997 ◽  
Vol 89 (8) ◽  
pp. 2706-2716 ◽  
Author(s):  
Nobuko Uchida ◽  
Zhi Yang ◽  
Jesse Combs ◽  
Olivier Pourquié ◽  
Megan Nguyen ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Molecular Cloning ◽  
Bone Marrow Cells ◽  
Hematopoietic Cell ◽  
Cell Antigen ◽  
Adult Bone Marrow ◽  
Cd34 Cells ◽  
Adult Bone ◽  
Marrow Cells ◽  
Myeloid Progenitors

Abstract The adhesion molecule BEN/SC1/DM-GRASP (BEN) is a marker in the developing chicken nervous system that is also expressed on the surface of embryonic and adult hematopoietic cells such as immature thymocytes, myeloid progenitors, and erythroid progenitors. F84.1 and KG-CAM, two monoclonal antibodies to rat neuronal glycoproteins with similarity to BEN, cross-react with an antigen on rat hematopoietic progenitors, but F84.1 only also recognizes human blood cell progenitors. We have defined the antigen recognized by F84.1 as the hematopoietic cell antigen (HCA). HCA expression was detected on 40% to 70% of CD34+ fetal and adult bone marrow cells and mobilized peripheral blood cells. Precursor cell activity for long-term in vitro bone marrow cell culture was confined to the subset of CD34+ cells that coexpress HCA. HCA is expressed by the most primitive subsets of CD34+ cells, including all rhodamine 123lo, Thy-1+, and CD38−/lo CD34+ adult bone marrow cells. HCA was also detected on myeloid progenitors but not on early B-cell progenitors. We also describe here the cloning and characterization of cDNAs encoding two variants of the human HCA antigen (huHCA-1 and huHCA-2) and of a cDNA clone encoding rat HCA (raHCA). The deduced amino acid sequences of huHCA and raHCA are homologous to that of chicken BEN. Recombinant proteins produced from either human or rat HCA cDNAs were recognized by F84.1, whereas rat HCA but not human HCA was recognized by antirat KG-CAM. Expression of either form of huHCA in CHO cells conferred homophilic adhesion that could be competed with soluble recombinant huHCA-Fc. The molecular cloning of HCA and the availability of recombinant HCA should permit further evaluation of its role in human and rodent hematopoiesis.

scholarly journals Thrombopoietin Is Synthesized by Bone Marrow Stromal Cells

Blood ◽  
1997 ◽  
Vol 90 (9) ◽  
pp. 3444-3455 ◽  
Author(s):  
Anastasia Guerriero ◽  
Lydia Worford ◽  
H. Kent Holland ◽  
Gui-Rong Guo ◽  
Kevin Sheehan ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Progenitor Cells ◽  
Stromal Cells ◽  
Cell Sorting ◽  
Bone Marrow Cells ◽  
Adult Bone Marrow ◽  
Hla Dr ◽  
Adult Bone ◽  
Marrow Cells

Abstract We have previously characterized stromal progenitor cells contained in fetal bone marrow by fluorescence-activated cell sorting (FACS) using the differential expression of CD34, CD38, and HLA-DR, and found that a small number were contained within the CD34+ cell fraction. In the present study, the frequency of stromal progenitors in both the CD34+ and CD34− subpopulations from samples of fetal and adult bone marrow was approximately one in 5,000 of the mononuclear cell fraction. Using multiparameter single-cell sorting, one in 20 fetal bone marrow cells with the CD34+, CD38−, HLA-DR−, CDw90+ phenotype were clonogenic stromal progenitors, whereas greater than one in five single cells with the CD34−, CD38−, HLA-DR−, CDw90+ phenotype formed stromal cultures. We found that cultures initiated by hematopoietic and stromal progenitors contained within the CD34+ fraction of bone marrow cells formed mixed hematopoietic/stromal cell cultures that maintained the viability of the hematopoietic progenitor cells for 3 weeks in the absence of added hematopoietic cytokines. We characterized some of the hematopoietic cytokines synthesized by stromal cultures derived from either CD34+ or CD34− bone marrow cells using reverse transcriptase–polymerase chain reaction (RT-PCR) amplification of interleukin-3 (IL-3), stem cell factor (SCF), CD34, Flt3/Flk2 ligand (FL), and thrombopoietin (TPO) mRNA sequences. We found ubiquitous expression of TPO mRNA in greater than 90% of stromal cultures initiated by either CD34+ or CD34− cells, and variable expression of SCF, FL, and CD34 mRNA. In particular, SCF and CD34 mRNA were detected only in stromal cultures initiated by CD34+ bone marrow cells, although the differences between CD34+ and CD34− stromal cells were not statistically significant. IL-3 mRNA was not found in any stromal cultures. An enzyme-linked immunosorbent assay (ELISA) of soluble SCF and TPO present in culture supernatants demonstrated that biologically significant amounts of protein were secreted by some cultured stromal cells: eight of 16 samples of conditioned media from stromal cultures initiated by fetal and adult bone marrow contained more than 32 pg/mL SCF (in the linear range of the ELISA), with a median value of 32 pg/mL (range, 9 to 230), while 13 of 24 samples of conditioned media had more than 16 pg/mL TPO (in the linear range of the ELISA), with a median of 37 pg/mL (range, 16 to 106). Our data indicate that stromal cultures initiated by single bone marrow cells can make FL, SCF, and TPO. Local production of early-acting cytokines and TPO by stromal cells may be relevant to the regulation of hematopoietic stem cell self-renewal and megakaryocytopoiesis in the bone marrow microenvironment.

scholarly journals B-lymphocyte heterogeneity: ontogenetic development and organ distribution of B-lymphocyte populations defined by their density of surface immunoglobulin.

1976 ◽  
Vol 144 (2) ◽  
pp. 494-506 ◽  
Author(s):  
I Scher ◽  
S O Sharrow ◽  
R Wistar ◽  
R Asofsky ◽  
W E Paul
Keyword(s):  
Bone Marrow ◽  
B Lymphocytes ◽  
B Lymphocyte ◽  
Bone Marrow Cells ◽  
Large Population ◽  
Organ Distribution ◽  
Spleen Cells ◽  
Adult Bone Marrow ◽  
Flow Microfluorometry ◽  
Adult Bone

The density of total Ig and of IgM, IgG1, IgG2, and IgA on the surface of adult murine splenic B lymphocytes was measured using the technique of rapid flow microfluorometry. In addition, the density of total surface Ig and of IgM on B lymphocytes derived from adult bone marrow, lymph nodes, and Peyer's patches, and from neonatal spleen was determined. Adult spleen and lymph node B lymphocytes are characterized by the presence of a large population of cells with a low-to-intermediate density of total surface Ig, which is seen as a peak in the fluorescence profiles when these cells are labeled with fluorescein-conjugated (F1) anti-Ig. This peak is not detected when neonatal spleen or adult bone marrow are examined; the development of this peak among spleen cells occurs during the first 4 wk of life. Although the characteristic fluorescence intensity peak is not seen when adult spleen cells are labeled with Fl anti-mu, changes in the density of surface IgM do occur during the first few weeks of life and are detected as a decrease in the frequency of cells which have relatively large amounts of surface IgM. The differences seen in the fluorescence patterns of adult spleen cells labeled with Fl anti-Ig and Fl anti-mu may be due to the appearance of IgD on the surface of mature splenic B lymphocytes. This is supported by the similarity of the fluorescence profiles of adult bone marrow cells stained with Fl anti-Ig and Fl anti-mu, as the latter population of cells is reported to lack surface IgD.

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