hematopoietic stem cells

(noun)

Multipotent stem cells that give rise to all the blood cell types from the myeloid (monocytes and macrophages, neutrophils, basophils, eosinophils, erythrocytes, megakaryocytes/platelets, and dendritic cells), and lymphoid lineages (T-cells, B-cells, and NK-cells).

Related Terms

Examples of hematopoietic stem cells in the following topics:

  • Development of Blood

    • Hematopoietic stem cells reside in the bone marrow and have the unique ability to differentiate into all mature blood cell types.
    • Hematopoietic stem cells (HSCs) reside in the bone marrow and have the unique ability to give rise to all of the different mature blood cell types.
    • For the stem cells and other undifferentiated blood cells in the bone marrow, blood cells are determined to specific cell types at random.
    • Colony-stimulating factors (CSFs) are secreted glycoproteins that bind to receptor proteins on the surfaces of hematopoietic stem cells, thereby activating intracellular signaling pathways that can cause the cells to proliferate and differentiate into a specific kind of blood cell.
    • A comprehensive diagram showing the development of different blood cells from hematopoietic stem cell to mature cells.

  • Development of Blood and Blood Vessels

    • Endothelial stem cells (ESCs) are one of three types of stem cells found in bone marrow.
    • They give rise to endothelial progenitor cells (EPCs), intermediate stem cells that lose potency.
    • Progenitor stem cells are committed to differentiating along a particular cell developmental pathway.
    • The lineages arising from the EPC and the hematopoietic progenitor cell (HPC) form the blood circulatory system.
    • Hematopoietic stem cells can undergo self-renewal and give rise to erythrocytes (red blood cells), megakaryocytes/platelets, mast cells, T-lymphocytes, B-lymphocytes, dendritic cells, natural killer cells, monocyte/macrophage, and granulocytes.

  • Medical Uses of Hematopoietic Growth Factors

    • Hemopoetic growth factors regulate the growth, differentiation, and proliferation of progenitor cells in the blood and bone marrow.
    • Hemopoietic growth factors regulate the differentiation and proliferation of particular progenitor cells.
    • Erythropoietin is a sialoglycoprotein hormone produced by peritubular cells of kidney.
    • G-CSF stimulates the production of white blood cells (WBC).
    • G-CSF is also used to increase the number of hematopoietic stem cells in the blood of the donor before collection by leukapheresis for use in hematopoietic stem cell transplantation.

  • Maturation of T Cells

    • T cells originate from hematopoietic stem cells in the bone marrow and undergo positive and negative selection in the thymus to mature.
    • They are distinguished from other lymphocytes, such as B cells and natural killer cells (NK cells), by the presence of a T cell receptor (TCR) on the cell surface.
    • All T cells originate from hematopoietic stem cells in the bone marrow, which are capable of differentiating into any type of white blood cell.
    • A T cell is then signaled by the thymus to become a CD4+ cell by reducing expression of its CD8 cell surface receptors.
    • The remaining cells exit the thymus as mature naive T cells.

  • Ruptured Spleen

    • Current knowledge of its purpose includes the removal of old red blood cells and platelets, and the detection of and fight against certain bacteria.
    • It is also known to function as a site for the development of new red blood cells from their hematopoietic stem cell precursors, particularly in situations in which the bone marrow (the normal site for this process) has been compromised by a disorder such as leukemia.

  • Clonal Selection and T-Cell Differentiation

    • The increased binding affinity may be why memory cells can eliminate a pathogen more rapidly than the original generation of effector cells.
    • Cloned daughter cells differentiate into either effector T cells or memory T cells.
    • Cytotoxic effector T cells are finished, but helper T cells continue to differentiate into individual subsets of helper T cells.
    • A hematopoietic stem cell undergoes differentiation and genetic rearrangement to produce lymphocytes in the immune system.
    • Clonal selection of lymphocytes: 1) A hematopoietic stem cell undergoes differentiation and genetic rearrangement to produce 2) immature lymphocytes with many different antigen receptors.

  • Cancer Immunology

    • Cancer immunology examines the interaction between cancer cells and the immune system.
    • Lymphocytes act as sentinels in recognizing and eliminating continuously-arising, nascent transformed cells.
    • Topical immunotherapy utilizes an immune enhancement cream (imiquimod) which is an interferon producer causing the patients own killer T cells to destroy warts, actinic keratoses, basal cell cancer, vaginal intraepithelial neoplasia, squamous cell cancer, cutaneous lymphoma, and superficial malignant melanoma.
    • Various cells that participate in immune functions.
    • Note that even though hematopoietic stem cell, erythrocyte, maegakaryocyte and platelets are found in the blood, they do not participate in immune functions.

  • Aging and the Immune System

    • Hematopoietic stem cells (HSC) provide the regulated lifelong supply of leukocyte progenitors that in turn differentiate into specialized immune cells (including lymphocytes, antigen-presenting dendritic cells and phagocytes).
    • With age, these stem cells diminish in their self-renewal capacity due to the accumulation of oxidative damage to DNA by cellular metabolic activity and shortening of telomeric terminals of chromosomes.
    • The cytotoxicity of natural killer (NK) cells and the antigen-presenting function of dendritic cells also diminish.
    • After birth, the decline of T-cell function begins with the progressive involution of the thymus, the organ essential for T-cell maturation following the migration of precursor cells from the bone marrow.
    • This age-associated decrease of thymic epithelial volume results in a reduction of the number of thymocytes (i.e. pre-mature T-cells), thus reducing output of peripheral naïve T-cells.

  • Development of the Immune System

    • Antigen-presenting cells in newborns have a reduced capability to activate T cells, proliferate poorly, and produce very small amounts of cytokines like IL-2, IL-4, IL-5, IL-12, and IFN-g.
    • B cells develop early in gestation but are not fully active.
    • There is some evidence that cell surface receptors on B cells and macrophages may detect sex hormones in the system.
    • The lymphoid vs. myeloid model of lymphopoiesis has the virtue of relative simplicity and agreement with nomenclature and terminology, as well as validity for tests with mice. pHSC pluripotent, self-renewing, hematopoietic stem cells give rise to MPP multipotent progenitors (these give rise to ELP, or PRO, prolymphocytes); early lymphoid progenitors; and finally to the CLP common lymphoid progenitor, a cell type fully committed to the lymphoid lineage. pHSC, MPP and ELP cells are not fully committed to the lymphoid lineage because if one is removed to a different location, it may differentiate into non-lymphoid progeny.
    • NK cells Dendritic cells (lymphoid lineage; DC2) Progenitor B cells Pro-B cells => Early Pro (or pre-pre)-B cells => Late Pro (or pre-pre)-B cells Large Pre-B cells => Small Pre-B cells Immature B cells B Cells => (B1 cells; B2 cells) Plasma cells Pro-T cells T-cells.

  • WBC Formation

    • Haematopoiesis refers to the formation of blood cells components.
    • All cellular blood components are derived from haematopoietic stem cells located within the bone marrow.
    • Haematopoietic stem cells (HSCs) reside in the bone marrow and have the unique ability to give rise to all mature blood cell types through differentiation into other progenitor cells.
    • When they proliferate, at least some daughter cells remain HSCs, so the pool of stem cells does not become depleted over time.
    • The lymphocyte lineage derives from common lymphoid progenitor cells, which in turn become lymphoblasts before differentiating into T cells, B cells, and NK cells.