Hematopoiesis Lecture 2 PDF

MT 61 | BSMLS-3A-3D | A.Y. 2024-2025 HEMATOPOIESIS STEM CELL THEORIES ❖ Monophyletic Theory 🖝 All blood cells are derived from single Pluripotent Hematopoietic stem...

MT 61 | BSMLS-3A-3D | A.Y. 2024-2025 HEMATOPOIESIS STEM CELL THEORIES ❖ Monophyletic Theory 🖝 All blood cells are derived from single Pluripotent Hematopoietic stem cell 🖝 Most widely accepted ❖ Polyphyletic Theory 🖝 Each of the blood cell lineages is derived from its own unique stem cell Noncommitted or Undifferentiated Hematopoietic Stem Cells ❖ capable of self-renewal ❖ have a high degree of proliferative capability ❖ pluripotent ❖ morphologically unrecognizable cells ❖ give rise to differentiated progenitor cells Committed or Differentiated Progenitor Cells ❖ descendants of stem cells that can differentiate further into a specific cell lineage ❖ morphologically unrecognizable cells ❖ Two types of Multilineage-specific Progenitor Cells 1. Commo Myeloid Progenitor 2. Common Lymphoid Progenitor ❖ Multilineage progenitors → Unilineage progenitors → give rise to precursor cells Culture-Derived Colony-Forming Units (CFUs) Abbreviation Cell Line CFU-GEMM Granulocyte, erythrocyte, megakaryocyte, monocyte CFU-E Erythrocyte CFU-Meg Megakaryocyte CFU-M Monocyte CFU-GM Granulocyte, monocyte CFU-Baso Myeloid to basophil CFU-Eo Myeloid to eosinophil CFU-G Myeloid to neutrophil CFU-pre-T T lymphocyte CFU-pre-B B lymphocyte PREPARED BY: KAREN B. ROSETE, RMT 1  MT 61 | BSMLS-3A-3D | A.Y. 2024-2025 Precursor Cells ❖ committed to forming a particular type of blood cell ❖ morphologically recognizable cells ❖ lineage-specific MODEL OF HEMATOPOIESIS ❖ Pluripotent HSCs → Common Myeloid Progenitor → Granulocytic, Monocytic, Erythrocytic, Megakaryocytic Lineage ❖ Pluripotent HSCs → Common Lymphoid Progenitor → T, B, NK-Lymphocytes, Dendritic Lineages ❖ Stem Cell Markers CD 34: Lymphoid & Myeloid Precursors CD 33 & CD38: Committed Myeloid Progenitor CD 10 & CD 38: Committed Lymphoid Progenitors CD 7: T-lymphoid Progenitor cells CD 19: B-lymphoid Progenitor Cells THREE POSSIBLE FATES OF HEMATOPOIETIC STEM CELL ❖ Self-renewal ❖ Differentiation Symmetric Division ❖ Apoptosis 🖝 HSCs divide → 2 identical daughter cells → both daughter cells leave the stem cell pool → undergo differentiation Asymmetric Division 🖝 HSCs divide → 2 identical daughter cells → 1 daughter cell remains in the stem cell pool | 1 daughter cell leaves the stem cell pool → undergo differentiation Apoptosis  HSCs divide → 2 identical daughter cells → undergo apoptosis THEORIES ON THE FATE OF THE STEM CELL ❖ Stochastic Model (Till and McCulloch) 🖝 HSC randomly commits to self-renewal or differentiation ❖ Instructive Model 🖝 Microenvironment in the BM determines whether the HSC will self-renew or differentiate Note: Currently, a combination of both theories is accepted. Initial decision: HSC randomly commits to self-renewal or differentiation (Stochastic) → decision to proceed with lineage differentiation in the presence of various signals from the hematopoietic inductive microenvironment of the BM (Instructive) → cell differentiation and maturation occur PREPARED BY: KAREN B. ROSETE, RMT 2  MT 61 | BSMLS-3A-3D | A.Y. 2024-2025 MORPHOLOGIC CHANGES THAT OCCUR AS CELL DIFFERENTIATES AND MATURES ❖ Overall decrease in cell volume and decrease in the ratio of nucleus and cytoplasm (N:C ratio) ❖ Changes in the nucleus Loss of nucleoli ↓ diameter of nucleus Condensation of nuclear chromatin Shape of nucleus Loss of nucleus ❖ Changes in the cytoplasm ↓ in basophilia ↑ proportion of cytoplasm Possible appearance of granules in the cytoplasm SIGNALS FROM THE HEMATOPOIETIC INDUCTIVE MICROENVIRONMENT ❖ Intrinsic Factors 🖝 Intrinsic regulation involves genes TAL1 – expressed in the cells in the hemangioblast (bipotential progenitor cell of mesodermal origin) GATA2 – expressed in late-appearing HSCs 🖝 TAL1 and GATA2 are essential for primitive and definitive hematopoiesis ❖ Extrinsic Factors 🖝 Extrinsic regulation involves growth factors/cytokines ❖ Regulatory Signaling Factors 🖝 Allow HSCs to respond to hematopoietic inductive microenvironment Notch-1 Notch-2 HEMATOPOIETIC GROWTH FACTORS OR CYTOKINES ❖ group of specific glycoproteins that regulate the proliferation, differentiation and maturation of hematopoietic precursor cells ❖ Cytokines include: interleukins (ILs), lymphokines, monokines, interferons, chemokines, and colony-stimulating factors (CSFs) ❖ have stimulatory or inhibitory effects 🖝 Cytokines that exert positive influence (stimulatory) KIT ligand FLT3 ligand GM-CSF IL-1 IL-3 IL-6 IL-11 🖝 Cytokines that exert negative influence (inhibitory) Growth factor-β Tumor necrosis factor- Interferons PREPARED BY: KAREN B. ROSETE, RMT 3  MT 61 | BSMLS-3A-3D | A.Y. 2024-2025 ❖ Roles of Cytokines 1. Inhibit apoptosis 2. Stimulate cells to divide by ↓ the transit time from G0 to G1 of the cell cycle 3. Regulate cell differentiation into the various cell lineages Apoptosis  Programmed cell death  Natural physiologic process  Eliminates unwanted, abnormal or harmful cells  When cells do not receive the appropriate cytokines necessary to prevent cell death, apoptosis is initiated COLONY-STIMULATING FACTORS Examples: GM-CSF (Granulocyte-Macrophage Colony stimulates formation of CFU-GM (colony-forming unit for Stimulating Factor) granulocyte & monocyte/macrophage also known as Granulocyte-Monocyte Progenitor) M-CSF (Macrophage-Stimulating Factor) stimulates formation of CFU-M (colony-forming unit- monocyte) G-CSF (Granulocyte-Stimulating Factor) stimulates formation of CFU-G (colony-forming unit- granulocyte) EARLY-ACTING MULTILINEAGE GROWTH FACTORS ❖ KIT Ligand (Stem Cell Factor) 🖝 Receptor: KIT Receptor-type tyrosine-protein kinase expressed on HSCs Downregulated with differentiation ❖ FLT3 Ligand 🖝 Receptor: FLT3 INTERLEUKINS ❖ Protein molecules that regulate hematopoiesis ❖ They have synergistic interactions with other cytokines to stimulate proliferation and differentiation of specific cell lines ❖ Effective at very low concentrations Note: Please refer to Turgeon, M.L. (2012). Clinical Hematology: Theory and Procedures. (5th Ed.). Philadelphia: Lippincott Williams & Wilkins, pp. 80-82 for the Summary of Interleukins PREPARED BY: KAREN B. ROSETE, RMT 4  MT 61 | BSMLS-3A-3D | A.Y. 2024-2025 SELECTED HEMATOPOIETIC GROWTH FACTORS OR CYTOKINES Cytokine/Growth Primary Cell Source Primary Target Cell Biological Activity Factor ❖ Kidney (peritubular ❖ Bone marrow ❖ Simulates proliferation of EPO interstitial cell) erythroid erythroid progenitors and progenitors (BFU-E prevents apoptosis of CFU-E and CFU-E) ❖ Endothelial cells ❖ Neutrophil ❖ Stimulates granulocyte G-CSF ❖ Placenta precursors colonies ❖ Monocytes ❖ Fibroblasts ❖ Differentiation of progenitors ❖ Macrophages ❖ Leukemic toward neutrophil lineage myeloblasts ❖ Stimulation of neutrophil maturation GM-CSF ❖ T cells ❖ Bone marrow ❖ Promotes antigen presentation ❖ Macrophages progenitor cells ❖ T cell homeostasis ❖ Endothelial cells ❖ Dendritic cells ❖ Hematopoietic cell growth ❖ Fibroblasts ❖ Macrophages factor ❖ Mast cells ❖ NKT cells IL-2 ❖ CD4+ T cells ❖ T cells ❖ Cell growth/activation of CD4+ ❖ NK cells ❖ NK cells and CD8+ T cells ❖ B cells ❖ B cells ❖ Suppress Treg responses ❖ Monocytes ❖ Mediator of immune tolerance ❖ Activated T cells ❖ Hematopoietic stem ❖ Proliferation of hematopoietic IL-3 ❖ NK cells cells and progenitors progenitors ❖ T cells ❖ T cells ❖ Co-stimulation with other IL-6 ❖ Macrophages ❖ B cells cytokines ❖ Fibroblasts ❖ Liver ❖ Cell growth/activation of T cells and B cells ❖ Megakaryocyte maturation ❖ Neural differentiation ❖ Acute phase reactant ❖ CD4+, Th2 T cells ❖ T cells ❖ Inhibits cytokine production IL-10 ❖ CD8+ T cells ❖ Macrophages ❖ Inhibits macrophages ❖ Monocytes ❖ Macrophages IL-12 ❖ Macrophages ❖ T cells ❖ T cell, Th1 differentiation ❖ CD4+ T cells ❖ CD4+/CD8+ T cell IL-15 ❖ Activated CD4+ T ❖ CD8+ T cells proliferation cells ❖ NK cells ❖ CD8+/NK cell cytotoxicity ❖ Dendritic cells ❖ Macrophages ❖ Antiviral IFN- ❖ NK cells ❖ NK cells ❖ Enhances MHC expression ❖ T cells ❖ B cells ❖ Macrophages ❖ Fibroblasts ❖ Endothelial cells PREPARED BY: KAREN B. ROSETE, RMT 5  MT 61 | BSMLS-3A-3D | A.Y. 2024-2025 ❖ Osteoblasts BFU-E, Burst-forming unit–erythroid; CFU-E, colony-forming unit–erythroid; EPO, erythropoietin; G-CSF, granulocyte colony- stimulating factor; GM-CSF, granulocyte-macrophage colony-stimulating factor; IFN, interferon; IL, interleukin; NK, natural killer; NKT, natural killer T cells; Th1, T helper, type 1; Th2, T helper, type 2; T reg, regulatory T cells LINEAGE-SPECIFIC HEMATOPOIESIS ERYTHROPOIESIS ❖ Production of erythrocytes Pluripotent HSC → Common Myeloid Progenitor/CFU-GEMM → BFU-E → CFU-E → Erythroid Precursor Cells → Mature erythrocytes Note: Burst-Forming Unit – Erythroid (BFU-E): contains few receptors for EPO Colony-Forming Unit – Erythroid (CFU-E): contains many receptors for EPO ❖ Erythropoietin (EPO) 🖝 Lineage-specific glycoprotein hormone produced specifically by the peritubular interstitial cells of the kidney 🖝 A small amount of it is produced in the liver 🖝 Stimulus for production and secretion of EPO: oxygen availability in the kidneys  ↓ oxygen → ↑ EPO production 🖝 Stimulates RBC production by: 1. Recruitment of CFU-E from BFU-E 2. Preventing apoptosis of erythroid progenitors 3. Inducing hemoglobin synthesis LEUKOPOIESIS ❖ Production of leukocytes Two Major Categories ❖ Myelopoiesis → production of monocytes and granulocytes (neutrophils, basophil, eosinophil) CFU-Eo → Precursor Cells → Eosinophil Pluripotent HSC → CMP/CFU-GEMM CFU-Baso → Immature Basophil → Mature Basophil CFU-GM/GMP CFU-G → Precursor Cells → Neutrophil CFU-M → Precursor Cells → Monocyte PREPARED BY: KAREN B. ROSETE, RMT 6  MT 61 | BSMLS-3A-3D | A.Y. 2024-2025 Note: CFU-Eo: Colony-Forming-Unit – Eosinophil/Eosinophil Progenitor CFU-Baso: Colony-Forming-Unit – Basophil/Basophil Progenitor CFU-GM: Colony-Forming-Unit – Granulocyte & Monocyte/Macrophage; it is also known as Granulocyte- Monocyte/Macrophage Progenitor (GMP) ❖ Lymphopoiesis → production of lymphocytes Natural Killer (NK) cells Pluripotent HSC → Common Lymphoid Progenitor CFU-pre-B → Precursor Cells → Mature B cells CFU-pre-T → Precursor Cells → Mature T cells MEGAKARYOPOIESIS ❖ Production of platelets Pluripotent HSC → CMP/CFU-GEMM → Megakaryocyte progenitors (Burst-Forming Unit-Meg/BFU-Meg → CFU- Meg → Light Density-CFU-Meg/LD-CFU-Meg) → Precursor cells → Platelets MAIN REFERENCES: ❖ Keohane, E.M., Otto, C.N., Walenga, J.M. (2020). Rodak’s Hematology: Clinical Principles and Applications. (6th Ed.). Singapore: Elsevier ❖ Keohane, E.M., Smith, L.J., Walenga, J.M. (2016). Rodak’s Hematology: Clinical Principles and Applications. (5th Ed.). Missouri: Elsevier Saunders ❖ Steininger, C.A., Martin, E. S., Koepke, J.A. (1992). Clinical Hematology: Principles, Procedures, Correlations. Philadelphia: J.B. Lippincott Company ❖ Turgeon, M.L. (2012). Clinical Hematology: Theory and Procedures. (5th Ed.). Philadelphia: Lippincott Williams & Wilkins PREPARED BY: KAREN B. ROSETE, RMT 7