Early megakaryocyte lineage-committed progenitors in adult mouse bone marrow.

Hematopoietic stem cells (HSCs) have been considered to progressively lose their self-renewal and differentiation potentials prior to the commitment to each blood lineage. However, recent studies have suggested that megakaryocyte progenitors (MkPs) are generated at the level of HSCs. In this study, we newly identified early megakaryocyte lineage-committed progenitors (MgPs) mainly in CD201CD48 cells and CD48 cells separated from the CD150CD34KitSca-1Lin HSC population of the bone marrow in adult mice.

Myelodysplastic syndromes are multiclonal diseases derived from hematopoietic stem and progenitor cells.

Myelodysplastic syndromes (MDS) are generally considered as a group of clonal diseases derived from hematopoietic stem cells, but a number of studies have suggested that they are derived from myeloid progenitor cells. We aimed to identify the cell of origin in MDS by single-cell analyses. Targeted single-cell RNA sequencing, covering six frequently mutated genes (U2AF1, SF3B1, TET2, ASXL1, TP53, and DNMT3A) in MDS, was developed and performed on individual cells isolated from the CD34 and six lineage populations in the bone marrow of healthy donors (HDs) and patients with MDS.

Multiple cells of origin in common with various types of mouse N-Myc acute leukemia.

Little is known regarding whether the cell of origin differs among different leukemia types. To address this fundamental issue, we determined the cell of origin in five distinct types of acute leukemia induced by N-Myc overexpression in mice. CD150CD48CD41CD34c-KitSca-1Lin (KSL) (HSC1) cells, CD150CD48CD41CD34KSL (HSC2) cells, CD150CD41CD34KSL (HPC1) cells, CD150CD41CD34KSL (HPC2) cells, and CD150CD41CD34KSL (HPC3) cells were purified from the bone marrow of adult C57BL/6 mice, transduced with the N-Myc retrovirus vector, and transplanted into lethally irradiated mice.

Expansion of Quiescent Hematopoietic Stem Cells under Stress and Nonstress Conditions in Mice.

Hematopoietic stem cells (HSCs) are maintained in the quiescent state for protection from stress. How quiescent HSCs expand in vivo under stress and nonstress conditions, however, is poorly understood. Using the fluorescent ubiquitination-based cell cycle indicator (Fucci) mice, we analyzed quiescent and cycling HSCs in the bone marrow after transplantation and during development and aging.

Lymphoid-biased hematopoietic stem cells and myeloid-biased hematopoietic progenitor cells have radioprotection activity.

Radioprotection was previously considered as a function of hematopoietic stem cells (HSCs). However, recent studies have reported its activity in hematopoietic progenitor cells (HPCs). To address this issue, we compared the radioprotection activity in 2 subsets of HSCs (nHSC1 and 2 populations) and 4 subsets of HPCs (nHPC1-4 populations) of the mouse bone marrow, in relation to their in vitro and in vivo colony-forming activity.

[Application and Research Progress of Lineage Tracing in Differentiation Mechanism of Hematopoietic Stem Cells--Review].

Hematopoietic stem cells (HSCs) reside at the top of the hierarchy and have the ability to differentiate to variety of hematopoietic progenitor cells (HPCs) or mature hematopoietic cells in each system. At present, the procress of HSC and HPC differentiating to the complete hematopoietic system under physiological and stressed conditions is poorly understood. In vivo lineage tracing is a powerful technique that can mark the individual cells and identify the differentiation pathways of their daughter cells, it takes as a strong technical system to research HSC.

Gene knockout in highly purified mouse hematopoietic stem cells by CRISPR/Cas9 technology.

The CRISPR/Cas9 system has been used for genome editing of human and mouse cells. In this study, we established a protocol for gene knockout (KO) in mouse hematopoietic stem cells (HSCs). HSCs were highly purified from the bone marrow of tamoxifen-treated Cas9-EGFP/Cre-ER transgenic mice, maintained in serum-free polyvinyl alcohol culture with cytokines, lentivirally transduced with sgRNA-Crimson, and transplanted into lethally irradiated mice with competitor cells.

Analysis and Isolation of Mouse Leukemic Stem Cells.

Flow cytometry has been widely used in basic and clinical research for analysis of a variety of normal and malignant cells. Hematopoietic stem cells (HSCs) and leukemic stem cells (LSCs) can be highly purified by flow cytometry. Isolated HSCs and LSCs can be functionally identified by transplantation assays and can also be studied at the molecular level.

[Hematopoietic Stem Cells Differentiate into the Megakaryocyte Lineage--Review].

Abstract　　Hematopoietic stem cells are able to self-renewal and differentiate to all blood lineages. With the development of new technologies, recent studies have proposed the revised versions of hematopoiesis. In the classical model of hematopoietic differentiation, HSCs were located at the apex of hematopoietic hierarchy.

Differentiation of transplanted haematopoietic stem cells tracked by single-cell transcriptomic analysis.

How transplanted haematopoietic stem cells (HSCs) behave soon after they reside in a preconditioned host has not been studied due to technical limitations. Here, using single-cell RNA sequencing, we first obtained the transcriptome-based classifications of 28 haematopoietic cell types. We then applied them in conjunction with functional assays to track the dynamic changes of immunophenotypically purified HSCs in irradiated recipients within the first week after transplantation.

Granulocyte colony-stimulating factor directly acts on mouse lymphoid-biased but not myeloid-biased hematopoietic stem cells.

Granulocyte colony-stimulating factor (G-CSF) is widely used in clinical settings to mobilize hematopoietic stem cells (HSCs) into the circulation for HSC harvesting and transplantation. However, whether G-CSF directly stimulates HSCs to change their cell cycle state and fate is controversial. HSCs are a heterogeneous population consisting of different types of HSCs, such as myeloid-biased HSCs and lymphoid-biased HSCs.

[Research Advance on In Vitro Generation of Human Hematopoietic Stem Cells for Transplantation--Review].

Abstract　　Currently, hematopoietic stem cell (HSC) transplantation is widely used in the therapy of hematological malignancies, non-malignant refractory anemia, genetic diseases and certain tumors with satisfactory therapeutic efficacy. HSC sources used for transplantation include bone marrow, mobilized peripheral blood and neonate umbilical cord blood. However, for many patients, sufficient number of human leukocyte antigen (HLA) -matched HSC cannot be found for transplantation, because the number of HSC in these tissues is small and HLA-identical donors are rare.

Successful ex vivo expansion of mouse hematopoietic stem cells.

Ex vivo expansion of hematopoietic stem cells (HSCs) is considered the holy grail in stem cell biology and therapy, as it has long been difficult to make this procedure possible. Yamazaki's research team has established new, polyvinyl alcohol-based culture conditions and shown a significant expansion of mouse HSCs from a small number of cells after a month of culture. Surprisingly, expanded HSCs were able to reconstitute unconditioned normal mice.

Interleukin-12 supports in vitro self-renewal of long-term hematopoietic stem cells.

Hematopoietic stem cells (HSCs) self-renew or differentiate through division. Cytokines are essential for inducing HSC division, but the optimal cytokine combination to control self-renewal of HSC in vitro remains unclear. In this study, we compared the effects of interleukin-12 (IL-12) and thrombopoietin (TPO) in combination with stem cell factor (SCF) on in vitro self-renewal of HSCs.

Lineage marker expression on mouse hematopoietic stem cells.

Whether hematopoietic stem cells (HSCs) express lineage markers is controversial. In this study, we highly purified HSCs from the adult bone marrow of C57BL/6 mice and examined their gene expression and reconstitution potential. We first focused on the integrin family.

[Emerging role of Mitochondria in Maintenance of Hematopoietic Stem Cells--Review].

Mitochondria are double-membrane organelles existing only in eukaryotic cells. Mitochondria perform various important functions，such as producing energy，regulating signal transduction，and contributing to stress response. Recent studies have highlighted an important role of mitochondria in the determination of hematopoietic stem cells （HSC） fate.

Mouse acute leukemia develops independent of self-renewal and differentiation potentials in hematopoietic stem and progenitor cells.

The cell of origin, defined as the normal cell in which the transformation event first occurs, is poorly identified in leukemia, despite its importance in understanding of leukemogenesis and improving leukemia therapy. Although hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) were used for leukemia models, whether their self-renewal and differentiation potentials influence the initiation and development of leukemia is largely unknown. In this study, the self-renewal and differentiation potentials in 2 distinct types of HSCs (HSC1 [CD150CD41CD34LineageSca-1c-Kit cells] and HSC2 [CD150CD41CD34LineageSca-1c-Kit cells]) and 3 distinct types of HPCs (HPC1 [CD150CD41CD34LineageSca-1c-Kit cells], HPC2 [CD150CD41CD34LineageSca-1c-Kit cells], and HPC3 [CD150CD41CD34LineageSca-1c-Kit cells]) were isolated from adult mouse bone marrow, and examined by competitive repopulation assay.

TGF-β1 Negatively Regulates the Number and Function of Hematopoietic Stem Cells.

Transforming growth factor β1 (TGF-β1) plays a role in the maintenance of quiescent hematopoietic stem cells (HSCs) in vivo. We asked whether TGF-β1 controls the cell cycle status of HSCs in vitro to enhance the reconstitution activity. To examine the effect of TGF-β1 on the HSC function, we used an in vitro culture system in which single HSCs divide with the retention of their short- and long-term reconstitution ability.

PDK1 plays a vital role on hematopoietic stem cell function.

3-Phosphoinositide-dependent protein kinase 1 (PDK1) is a pivotal regulator in the phosphoinositide 3-kinase (PI3K)-Akt signaling pathway that have been shown to play key roles in the functional development of B and T cells via activation of AGC protein kinases during hematopoiesis. However, the role of PDK1 in HSCs has not been fully defined. Here we specifically deleted the PDK1 gene in the hematopoietic system and found that PDK1-deficient HSCs exhibited impaired function and defective lineage commitment abilities.

An All-Recombinant Protein-Based Culture System Specifically Identifies Hematopoietic Stem Cell Maintenance Factors.

Hematopoietic stem cells (HSCs) are considered one of the most promising therapeutic targets for the treatment of various blood disorders. However, due to difficulties in establishing stable maintenance and expansion of HSCs in vitro, their insufficient supply is a major constraint to transplantation studies. To solve these problems we have developed a fully defined, all-recombinant protein-based culture system.

Chasing the precursor of functional hematopoietic stem cells at the single cell levels in mouse embryos.

Background: Adult hematopoietic stem cells (HSCs), the ideal system for regenerative research, were isolated at single cell levels decades ago, whereas studies on embryonic HSCs are much more difficult.

Methods: Zhou et al identified a new pre-HSC cell surface marker, CD201, by which they isolated pre-HSCs at single cell levels for further analyses.

Results: The novel expression pattern of HSC development is revealed, including the fundamental role of mammalian targets of rapamycin (mTOR) signaling pathway in HSCs emergence, and the repopulation potential of S/G2/M phase pre-HSCs.

A novel lymphoid progenitor cell population (LSK(low)) is restricted by p18(INK4c).

The cyclin-dependent kinase inhibitor CDKN2C (p18(INK4c)) restrains self-renewal in hematopoietic stem cells (HSCs) and participates in the development and maturation of lymphoid cells. Deficiency in p18 predisposes mice and humans to hematopoietic lymphoid malignancies such as T-cell leukemia and multiple myeloma. However, the mechanism by which p18 regulates differentiation from HSCs to lymphoid cells is poorly understood.

Promotion of Expansion and Differentiation of Hematopoietic Stem Cells by Interleukin-27 into Myeloid Progenitors to Control Infection in Emergency Myelopoiesis.

Emergency myelopoiesis is inflammation-induced hematopoiesis to replenish myeloid cells in the periphery, which is critical to control the infection with pathogens. Previously, pro-inflammatory cytokines such as interferon (IFN)-α and IFN-γ were demonstrated to play a critical role in the expansion of hematopoietic stem cells (HSCs) and myeloid progenitors, leading to production of mature myeloid cells, although their inhibitory effects on hematopoiesis were also reported. Therefore, the molecular mechanism of emergency myelopoiesis during infection remains incompletely understood.