Hematopoietic Stem Cells in the Mouse Spleen

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2421-2421 ◽  
Author(s):  
Akiko Iseki ◽  
Yohei Morita ◽  
Hiromitsu Nakauchi ◽  
Hideo Ema
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Hematopoietic Stem Cells ◽  
Low Frequency ◽  
Extramedullary Hematopoiesis ◽  
Spleen Cells ◽  
Hematopoietic Stem ◽  
Hematopoietic Organ ◽  
Physiological Conditions ◽  
Cell Niche

Abstract The spleen is a hematopoietic organ in mice. Hematopoietic stem cells (HSCs) migrate into the spleen around embryonic day 14, and then migrate into the bone marrow (BM) around embryonic day 17. Thereafter, HSCs reside in both BM and spleen throughout the life of a mouse. The spleen is the major site of extramedullary hematopoiesis in pathological conditions. The spleen serves as an active hematopoietic organ in lethally irradiated mice for a while after transplantation with BM cells. Osteoblasts are considered to be one of the stem cell niche components. Because there are no osteoblasts in the spleen, niches in the spleen possibly functions differently from ones in the BM. The regulation of HSCs likely differs between the BM and spleen. In order to understand a role of spleen HSCs in physiological conditions, we have characterized HSCs in the spleen as compared with those in the BM. BM and spleen cells were obtained from 8–10 week-old C57BL/6 mice. Competitive repopulation showed that the repopulating activity per 106 BM cells was significantly greater than that per 106 spleen cells (about 10-fold). Limiting analysis showed that the frequency of long-term repopulating cells in BM cells was significantly higher than that in spleen cells (about 10-fold). As a result, the mean activity per BM stem cell was similar to that per spleen stem cell. Similarly to BM, CD34-negative, c-Kit-positive, Sca-1-positive, lineage markers-negative (CD34−KSL) cells were highly enriched in HSCs in the spleen. The frequency of CD34−KSL cells in the spleen was significantly lower than that in the BM. These data indicate that functionally equivalent HSCs exist in the spleen but at a low frequency. Data from single cell-transplantation supported this notion. The proportion of pyronin Y-negative G0 cells among BM CD34−KSL cells was greater than that among spleen CD34−KSL cells at any one time. BrdU-uptake analysis showed that spleen CD34− KSL cells were cycling more rapidly than BM CD34−KSL cells. These data suggest that spleen HSCs contribute to hematopoiesis to some extent under physiological conditions. BM and spleen HSCs may be interchangeable via the circulation. When BM HSCs are in the spleen, they are possibly under the control of spleen niches different from BM niches.

Zeb2-Defficiency in the Adult Murine Hematopoietic Precursor Cells Leads to Differentiation Defects in Multiple Hematopoietic Lineages and a Myeloproliferative-Like Phenotype

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1199-1199
Author(s):  
Tamara Riedt ◽  
Steven Goossens ◽  
Ines Gütgemann ◽  
Carmen Carrillo-Garcia ◽  
Hichem D Gallala ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Stem Cell ◽  
Hematopoietic Stem Cells ◽  
Hematopoietic Cells ◽  
Extramedullary Hematopoiesis ◽  
Independent Effect ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Reticular Fibers

Abstract Abstract 1199 The life long replenishment of highly specialized blood cells by a small number of hematopoietic cells (HSC) requires a strict regulation between self-renewal and differentiation in the immature compartment of the bone marrow. Perturbation of this equilibrium can result in stem cell loss or hematologic malignancies. This balance is at least in part controlled by a network of transcription factors. Zeb2 is a transcriptional repressor and plays an important role during the embryonic development as a modulator of the epithelial to mesenchymal transition (EMT) as well as tumor progression and metastasis. We have previously identified the essential role of Zeb2 in murine embryonic hematopoiesis, where selective Zeb2 deficiency in the hematopoietic stem cells resulted in early lethality around day 12.5. The aim of this study was to analyze whether Zeb2 plays a specific role in the regulation of homeostasis in the adult hematopoietic system. Using the Mx1-Cre based inducible Zeb2 conditional knock out mouse model we analyzed the impact of Zeb2 loss on adult hematopoietic stem cell function. Upon the induction of Zeb2 deletion we found a significant decrease in most cell lineages of the peripheral blood, except the neutrophil granulocytes. However, the reduction of mature cells in the blood was not accompanied by reduced bone marrow cellularity, as the cellularity was similar between Zeb2Δ/Δ Mx1-Cre (Zeb2 conditional KO) mice and the control animals (Zeb2+/+Mx1-Cre). However, in the bone marrow of the Zeb2Δ/Δ Mx1-Cre animals the granulocytic lineage was dominating, whereas other lineages e.g. red blood cell precursors and B-lymphoid precursors were drastically reduced. Histological sections of the bone marrow cavity revealed megacaryocytes with abnormal morphology reflecting maturation defects and an increased production of reticular fibers in the BM of Zeb2Δ/Δ Mx1-Cre mice. In addition Zeb2Δ/Δ Mx1-Cre mice displayed a two to three fold increase in spleen size compared to control animals due to an extramedullary hematopoiesis. Analysis of the primitive hematopoietic compartment in the bone marrow and spleens revealed that Zeb2 deletion resulted in a pronounced increase in the most immature hematopoietic cells, defined as Lin-Sca1+cKit+CD48-CD150+ population, and perturbation in different lineage restricted progenitor subpopulations. No difference in cell cycling or apoptotic rate in the stem cell enriched bone marrow population (Lin-Sca1+cKit+CD48-CD150+) was detectable between the genotypes. Upon transplantation into lethally irradiated wild type recipients, Zeb2 deficient stem cells demonstrated significantly reduced ability to differentiate into multiple hematopoietic lineages indicating a niche independent effect of Zeb2 in promoting differentiation of hematopoietic stem cells. On the molecular level, gene expression analysis of hematopoietic stem and progenitor cells using microarray approach revealed increased transcripts of downstream targets of Wnt/ß-Catenin signaling, suggesting increased Wnt signaling activity in absence of Zeb2 in the hematopoietic compartment, which at least in part might be responsible for the observed phenotype. These data indicate that Zeb2 is involved in the regulation of the balance between self-renewal and differentiation at multiple stages of hematopoietic cell maturation. Furthermore the lack of Zeb2 in the hematopoietic compartment leads to a phenotype that resembles the features of human myeloproliferative disorders, especially the early stages of primary myelofibrosis with dominant granulopoiesis, production of reticular fibers in the bone marrow, and morphological abnormalities in megacaryocytes, accompanied by extramedullary hematopoiesis. Disclosures: No relevant conflicts of interest to declare.

Does primary myelofibrosis involve a defective stem cell niche? From concept to evidence

Blood ◽  
2008 ◽  
Vol 112 (8) ◽  
pp. 3026-3035 ◽  
Author(s):  
Jean-Jacques Lataillade ◽  
Olivier Pierre-Louis ◽  
Hans Carl Hasselbalch ◽  
Georges Uzan ◽  
Claude Jasmin ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Cell Proliferation ◽  
Stem Cell ◽  
Hematopoietic Stem Cells ◽  
Stem Cell Niche ◽  
Primary Myelofibrosis ◽  
Hematopoietic Stem ◽  
Stem Cell Proliferation ◽  
Cell Niche

Abstract Primary myelofibrosis (PMF) is the rarest and the most severe Philadelphia-negative chronic myeloproliferative syndrome. By associating a clonal proliferation and a mobilization of hematopoietic stem cells from bone marrow to spleen with profound alterations of the stroma, PMF is a remarkable model in which deregulation of the stem cell niche is of utmost importance for the disease development. This paper reviews key data suggesting that an imbalance between endosteal and vascular niches participates in the development of clonal stem cell proliferation. Mechanisms by which bone marrow niches are altered with ensuing mobilization and homing of neoplastic hematopoietic stem cells in new or reinitialized niches in the spleen and liver are examined. Differences between signals delivered by both endosteal and vascular niches in the bone marrow and spleen of patients as well as the responsiveness of PMF stem cells to their specific signals are discussed. A proposal for integrating a potential role for the JAK2 mutation in their altered sensitivity is made. A better understanding of the cross talk between stem cells and their niche should imply new therapeutic strategies targeting not only intrinsic defects in stem cell signaling but also regulatory hematopoietic niche–derived signals and, consequently, stem cell proliferation.

Aging of hematopoietic stem cells is regulated by the stem cell niche

2008 ◽  
Vol 43 (11) ◽  
pp. 974-980 ◽  
Author(s):  
Wolfgang Wagner ◽  
Patrick Horn ◽  
Simone Bork ◽  
Anthony D. Ho
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Hematopoietic Stem Cells ◽  
Stem Cell Niche ◽  
Hematopoietic Stem ◽  
Cell Niche

scholarly journals Long-Term Human Hematopoietic Stem Cell Culture in Microdroplets

Micromachines ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 90
Author(s):  
Pilar Carreras ◽  
Itziar González ◽  
Miguel Gallardo ◽  
Alejandra Ortiz-Ruiz ◽  
Maria Luz Morales ◽  
...  
Keyword(s):  
Stem Cells ◽  
Cell Culture ◽  
Stem Cell ◽  
Hematopoietic Stem Cells ◽  
Hematopoietic Stem Cell ◽  
Stem Cell Niche ◽  
Hematopoietic Stem ◽  
Stem Cell Culture ◽  
Cell Niche

We previously reported a new approach for micromanipulation and encapsulation of human stem cells using a droplet-based microfluidic device. This approach demonstrated the possibility of encapsulating and culturing difficult-to-preserve primary human hematopoietic stem cells using an engineered double-layered bead composed by an inner layer of alginate and an outer layer of Puramatrix. We also demonstrated the maintenance and expansion of Multiple Myeloma cells in this construction. Here, the presented microfluidic technique is applied to construct a 3D biomimetic model to recapitulate the human hematopoietic stem cell niche using double-layered hydrogel beads cultured in 10% FBS culture medium. In this model, the long-term maintenance of the number of cells and expansion of hHSCS encapsulated in the proposed structures was observed. Additionally, a phenotypic characterization of the human hematopoietic stem cells generated in the presented biomimetic model was performed in order to assess their long-term stemness maintenance. Results indicate that the ex vivo cultured human CD34+ cells from bone marrow were viable, maintained, and expanded over a time span of eight weeks. This novel long-term stem cell culture methodology could represent a novel breakthrough to improve Hematopoietic Progenitor cell Transplant (HPT) as well as a novel tool for further study of the biochemical and biophysical factors influencing stem cell behavior. This technology opens a myriad of new applications as a universal stem cell niche model potentially able to expand other types of cells.

G-CSF Induced Expansion and Mobilization of Hematopoietic Stem Cells Is Altered by the Matrix Protein Osteopontin.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1400-1400
Author(s):  
Randolf Forkert ◽  
Yon Ko ◽  
Thomas Neuhaus ◽  
Elisabeth Gruenewald ◽  
Silke Schoeneborn ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Stem Cell ◽  
Hematopoietic Stem Cells ◽  
Peripheral Blood ◽  
Stem Cell Niche ◽  
Wild Type ◽  
Hematopoietic Stem ◽  
Cell Mobilization ◽  
Cell Niche

Abstract Stem cells reside in a physical microenvironment or niche where a balance of signals controls their proliferation, differentiation and death. Components of the specialized microenvironment have generally been defined in terms of cells and signaling pathways affecting stem cell maintenance or expansion. We have defined a role for a matrix glycoprotein that provides a constraining function on hematopoietic stem cells within the bone marrow microenvironment. Osteopontin (OPN) is an abundant glycoprotein in bone that modifies primitive hematopoietic cell number and function in a stem cell non-autonomous manner. Here we analyzed the role of OPN for regulating stem cell mobilization and pool size in times of G-CSF induced marrow stress, a context close to the clinical setting of stem cell mobilization not well understood so far. Bone marrow stromal cells show an enhanced expression of OPN under stimulation with G-CSF, which prompted us to analyze the role of OPN in G-CSF mediated activation of the stem cell niche. First we treated OPN deficient mice and their wild-type littermates with G-CSF for 5 days. We could observe a significant increased stem cell fraction in the peripheral blood and in the bone marrow in the absence of OPN in comparison to the wild-type controls. To evaluate, if this effect is stroma dependent, we first transplanted wild-type bone marrow into wild-type or OPN-deficient recipients. 6 weeks after transplantation we treated these mice with G-CSF for 5 days and analyzed the peripheral blood and the bone marrow for the contents of primitive hematopoietic cells. Here we could detect a significantly increased stem cell fraction in peripheral blood and bone marrow of the OPN−/− recipients in comparison to wild type controls detected by FACS and functional in vitro stem cell assays. We then transplanted the stressed bone marrow in a competitive repopulation assay into wild-type recipients and observed a significant increase of CD45.2 cells from OPN−/− recipient mice up to 12 weeks after transplantation in comparison to wild-type controls, demonstrating an enhanced G-CSF induced expansion of hematopioetic stem cells in the OPN-deficient stem cell niche. Furthermore, we could observe an enhanced expression of Angiopoietin and N-Cadherin in OPN-deficient bone marrow stromal cells after stimulation with G-CSF in comparison to wild-type controls, supporting the stroma dependent expansion of stem cells in the absence of OPN in the G-CSF stimulated stem cell niche. Therefore, OPN is a restricting element of the stem cell niche limiting the size of the stem cell pool and may provide a dynamic mechanism by which excess stem cell expansion is prevented during times of niche stimulation. These findings may provide new insight into expansion and mobilization of hematopoietic stem cells by G-CSF mediated by components of the stem cell niche.

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