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Platelets: Histology

Platelets are small cell fragments involved in hemostasis Hemostasis Hemostasis refers to the innate, stepwise body processes that occur following vessel injury, resulting in clot formation and cessation of bleeding. Hemostasis occurs in 2 phases, namely, primary and secondary. Primary hemostasis involves forming a plug that stops the bleeding temporarily. Secondary hemostasis involves the activation of the coagulation cascade. Hemostasis. Thrombopoiesis takes place primarily in the bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types marrow through a series of cell differentiation and is influenced by several cytokines Cytokines Non-antibody proteins secreted by inflammatory leukocytes and some non-leukocytic cells, that act as intercellular mediators. They differ from classical hormones in that they are produced by a number of tissue or cell types rather than by specialized glands. They generally act locally in a paracrine or autocrine rather than endocrine manner. Adaptive Immune Response. Platelets are formed after fragmentation Fragmentation Chronic Apophyseal Injury of the megakaryocyte cytoplasm. As a result, platelets have a diameter of 2–3 μm. Nuclei are not present; however, a variety of organelles Organelles A cell is a complex unit that performs several complex functions. An organelle is a specialized subunit within a cell that fulfills a specific role or function. Organelles are enclosed within their own lipid bilayers or are unbound by membranes. The Cell: Organelles are present and aid in different platelet functions.

Last updated: Aug 15, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Overview

Definition

Platelets are small cell fragments without nuclei, but with a variety of organelles Organelles A cell is a complex unit that performs several complex functions. An organelle is a specialized subunit within a cell that fulfills a specific role or function. Organelles are enclosed within their own lipid bilayers or are unbound by membranes. The Cell: Organelles. Platelets are involved in primary hemostasis Hemostasis Hemostasis refers to the innate, stepwise body processes that occur following vessel injury, resulting in clot formation and cessation of bleeding. Hemostasis occurs in 2 phases, namely, primary and secondary. Primary hemostasis involves forming a plug that stops the bleeding temporarily. Secondary hemostasis involves the activation of the coagulation cascade. Hemostasis by adhering to damaged blood vessels and aggregating with one another ( platelet plug Platelet plug Hemostasis).

Description:

  • Diameter: 2–3 µm 
  • Lens-shaped biconvex discoid
  • Normal count: 150,000–450,000 platelets/µL
  • Lifespan: up to 10 days

Structure

  • Outer membrane: Receptors Receptors Receptors are proteins located either on the surface of or within a cell that can bind to signaling molecules known as ligands (e.g., hormones) and cause some type of response within the cell. Receptors facilitate platelet aggregation Aggregation The attachment of platelets to one another. This clumping together can be induced by a number of agents (e.g., thrombin; collagen) and is part of the mechanism leading to the formation of a thrombus. Coagulation Studies and adhesion Adhesion The process whereby platelets adhere to something other than platelets, e.g., collagen; basement membrane; microfibrils; or other ‘foreign’ surfaces. Coagulation Studies to endothelial surfaces.
  • Open canalicular system: tunnels from membranes to platelet interior:
    • For entry of exterior elements
    • For granule release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology
    • For storage of glycoproteins Glycoproteins Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins. Basics of Carbohydrates
  • In the cytoplasm:
    • α granules (most abundant) contain: 
      • Proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis for primary hemostasis Hemostasis Hemostasis refers to the innate, stepwise body processes that occur following vessel injury, resulting in clot formation and cessation of bleeding. Hemostasis occurs in 2 phases, namely, primary and secondary. Primary hemostasis involves forming a plug that stops the bleeding temporarily. Secondary hemostasis involves the activation of the coagulation cascade. Hemostasis (e.g., integrin)
      • Proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis such as von Willebrand Factor von Willebrand factor A high-molecular-weight plasma protein, produced by endothelial cells and megakaryocytes, that is part of the factor VIII/von Willebrand factor complex. The von Willebrand factor has receptors for collagen, platelets, and ristocetin activity as well as the immunologically distinct antigenic determinants. It functions in adhesion of platelets to collagen and hemostatic plug formation. The prolonged bleeding time in von Willebrand diseases is due to the deficiency of this factor. Hemostasis (vWF), fibrinogen Fibrinogen Plasma glycoprotein clotted by thrombin, composed of a dimer of three non-identical pairs of polypeptide chains (alpha, beta, gamma) held together by disulfide bonds. Fibrinogen clotting is a sol-gel change involving complex molecular arrangements: whereas fibrinogen is cleaved by thrombin to form polypeptides a and b, the proteolytic action of other enzymes yields different fibrinogen degradation products. Hemostasis, factor V Factor V Heat- and storage-labile plasma glycoprotein which accelerates the conversion of prothrombin to thrombin in blood coagulation. Factor V accomplishes this by forming a complex with factor Xa, phospholipid, and calcium (prothrombinase complex). Hemostasis, and factor XI (needed for secondary hemostasis Secondary hemostasis The coagulation cascade is a series of reactions that ultimately generates a strong, cross-linked fibrin clot. Hemostasis)
      • May have antiangiogenic-protein populations
      • May have proangiogenic-protein populations (e.g., vascular endothelial growth factor Vascular endothelial growth factor A family of angiogenic proteins that are closely-related to vascular endothelial growth factor a. They play an important role in the growth and differentiation of vascular as well as lymphatic endothelial cells. Wound Healing (VEGF))
    • δ granules contain:
      • Mediators of vascular tone: serotonin Serotonin A biochemical messenger and regulator, synthesized from the essential amino acid l-tryptophan. In humans it is found primarily in the central nervous system, gastrointestinal tract, and blood platelets. Serotonin mediates several important physiological functions including neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. Receptors and Neurotransmitters of the CNS, calcium Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Electrolytes 
      • ADP and ATP
    • Lysosomes Lysosomes A class of morphologically heterogeneous cytoplasmic particles in animal and plant tissues characterized by their content of hydrolytic enzymes and the structure-linked latency of these enzymes. The intracellular functions of lysosomes depend on their lytic potential. The single unit membrane of the lysosome acts as a barrier between the enzymes enclosed in the lysosome and the external substrate. The activity of the enzymes contained in lysosomes is limited or nil unless the vesicle in which they are enclosed is ruptured or undergoes membrane fusion. The Cell: Organelles with hydrolytic enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes:
      • Digest cytosolic contents
      • Participate in fibrinolysis and destruction of the extracellular matrix Extracellular matrix A meshwork-like substance found within the extracellular space and in association with the basement membrane of the cell surface. It promotes cellular proliferation and provides a supporting structure to which cells or cell lysates in culture dishes adhere. Hypertrophic and Keloid Scars
  • The cytoskeleton Cytoskeleton The network of filaments, tubules, and interconnecting filamentous bridges which give shape, structure, and organization to the cytoplasm. The Cell: Cytosol and Cytoskeleton (including actin Actin Filamentous proteins that are the main constituent of the thin filaments of muscle fibers. The filaments (known also as filamentous or f-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 amino acids long. This is known as globular or g-actin. In conjunction with myosins, actin is responsible for the contraction and relaxation of muscle. Skeletal Muscle Contraction, spectrin, tubulin Tubulin A microtubule subunit protein found in large quantities in mammalian brain. It has also been isolated from sperm flagellum; cilia; and other sources. Structurally, the protein is a dimer with a molecular weight of approximately 120, 000 and a sedimentation coefficient of 5. 8s. It binds to colchicine; vincristine; and vinblastine. Flucytosine, Griseofulvin, and Terbinafine, and filamin) is involved in:
    • Changing shape 
    • Motility Motility The motor activity of the gastrointestinal tract. Gastrointestinal Motility towards the site of injury 
    • Granule release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology
  • Contains: the Golgi complex Golgi complex A stack of flattened vesicles that functions in posttranslational processing and sorting of proteins, receiving them from the rough endoplasmic reticulum and directing them to secretory vesicles, lysosomes, or the cell membrane. The movement of proteins takes place by transfer vesicles that bud off from the rough endoplasmic reticulum or golgi apparatus and fuse with the golgi, lysosomes or cell membrane. The Cell: Organelles, elements of the rough endoplasmic reticulum Endoplasmic reticulum A system of cisternae in the cytoplasm of many cells. In places the endoplasmic reticulum is continuous with the plasma membrane (cell membrane) or outer membrane of the nuclear envelope. If the outer surfaces of the endoplasmic reticulum membranes are coated with ribosomes, the endoplasmic reticulum is said to be rough-surfaced; otherwise it is said to be smooth-surfaced. The Cell: Organelles (RER), mitochondria Mitochondria Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive ribosomes, transfer RNAs; amino Acyl tRNA synthetases; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs. Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. The Cell: Organelles, and glycogen granules
Platelet granule exocytosis

Schematic diagram of a platelet:
The platelet is a 2–3 μm discoid cell containing α-granules, dense granules Dense granules Hemostasis, lysosomes Lysosomes A class of morphologically heterogeneous cytoplasmic particles in animal and plant tissues characterized by their content of hydrolytic enzymes and the structure-linked latency of these enzymes. The intracellular functions of lysosomes depend on their lytic potential. The single unit membrane of the lysosome acts as a barrier between the enzymes enclosed in the lysosome and the external substrate. The activity of the enzymes contained in lysosomes is limited or nil unless the vesicle in which they are enclosed is ruptured or undergoes membrane fusion. The Cell: Organelles, and mitochondria Mitochondria Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive ribosomes, transfer RNAs; amino Acyl tRNA synthetases; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs. Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. The Cell: Organelles. Tunnel invaginations of the plasma membrane Plasma membrane A cell membrane (also known as the plasma membrane or plasmalemma) is a biological membrane that separates the cell contents from the outside environment. A cell membrane is composed of a phospholipid bilayer and proteins that function to protect cellular DNA and mediate the exchange of ions and molecules. The Cell: Cell Membrane form a complex membrane network, the open canalicular system, which courses throughout the platelet interior.

Image: “Platelet Granule Exocytosis Exocytosis Cellular release of material within membrane-limited vesicles by fusion of the vesicles with the cell membrane. The Cell: Cell Membrane” by Jennifer L Fitch-Tewfik and Robert Flaumenhaft. License: CC BY 3.0

Related videos

Thrombopoiesis

Platelet production

  • Hematopoiesis Hematopoiesis The development and formation of various types of blood cells. Hematopoiesis can take place in the bone marrow (medullary) or outside the bone marrow (extramedullary hematopoiesis). Bone Marrow: Composition and Hematopoiesis location:
    • 1st–2nd month in utero: mesoderm Mesoderm The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube. Gastrulation and Neurulation of the yolk sac Yolk Sac The first of four extra-embryonic membranes to form during embryogenesis. In reptiles and birds, it arises from endoderm and mesoderm to incorporate the egg yolk into the digestive tract for nourishing the embryo. In placental mammals, its nutritional function is vestigial; however, it is the source of intestinal mucosa; blood cells; and germ cells. It is sometimes called the vitelline sac, which should not be confused with the vitelline membrane of the egg. Embryoblast and Trophoblast Development
    • 2nd month: liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy and spleen Spleen The spleen is the largest lymphoid organ in the body, located in the LUQ of the abdomen, superior to the left kidney and posterior to the stomach at the level of the 9th-11th ribs just below the diaphragm. The spleen is highly vascular and acts as an important blood filter, cleansing the blood of pathogens and damaged erythrocytes. Spleen: Anatomy
    • 5th month: bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types marrow, which becomes the predominant source of blood cells
  • As with other blood cells, thrombopoiesis starts with multipotent hematopoietic stem cells Hematopoietic stem cells Progenitor cells from which all blood cells derived. They are found primarily in the bone marrow and also in small numbers in the peripheral blood. Bone Marrow: Composition and Hematopoiesis (HSCs).
  • HSCs → multipotent progenitor ( MPP MPP Specialized stem cells that are committed to give rise to cells that have a particular function; examples are myoblasts; myeloid progenitor cells; and skin stem cells. Bone Marrow: Composition and Hematopoiesis) cells → common myeloid progenitor (CMP) or colony-forming unit–granulocyte, erythrocyte, monocyte, megakaryocyte (CFU-GEMM) → fragmentation Fragmentation Chronic Apophyseal Injury of megakaryocyte (platelets)
Bone marrow hematopoiesis

Production and differentiation of the cells in the bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types marrow: Hematopoiesis Hematopoiesis The development and formation of various types of blood cells. Hematopoiesis can take place in the bone marrow (medullary) or outside the bone marrow (extramedullary hematopoiesis). Bone Marrow: Composition and Hematopoiesis or the production of all blood cells starts with a hematopoietic stem cell, which is prompted to divide and differentiate with appropriate chemical stimuli (hemopoietic growth factors).
CFU-GEMM: colony-forming unit–granulocyte, erythrocyte, monocyte, megakaryocyte
CFU-GM: colony-forming unit–granulocyte-macrophage
GM-CSF GM-CSF An acidic glycoprotein of mw 23 kda with internal disulfide bonds. The protein is produced in response to a number of inflammatory mediators by mesenchymal cells present in the hemopoietic environment and at peripheral sites of inflammation. GM-CSF is able to stimulate the production of neutrophilic granulocytes, macrophages, and mixed granulocyte-macrophage colonies from bone marrow cells and can stimulate the formation of eosinophil colonies from fetal liver progenitor cells. GM-CSF can also stimulate some functional activities in mature granulocytes and macrophages. White Myeloid Cells: Histology: granulocyte-macrophage colony-stimulating factor
M-CSF M-CSF A mononuclear phagocyte colony-stimulating factor (M-CSF) synthesized by mesenchymal cells. The compound stimulates the survival, proliferation, and differentiation of hematopoietic cells of the monocyte-macrophage series. M-CSF is a disulfide-bonded glycoprotein dimer with a mw of 70 kda. It binds to a specific high affinity receptor. White Myeloid Cells: Histology: macrophage colony-stimulating factor Macrophage colony-stimulating factor A mononuclear phagocyte colony-stimulating factor (M-CSF) synthesized by mesenchymal cells. The compound stimulates the survival, proliferation, and differentiation of hematopoietic cells of the monocyte-macrophage series. M-CSF is a disulfide-bonded glycoprotein dimer with a mw of 70 kda. It binds to a specific high affinity receptor. White Myeloid Cells: Histology
G-CSF: granulocyte colony-stimulating factor Granulocyte colony-stimulating factor A glycoprotein of mw 25 kda containing internal disulfide bonds. It induces the survival, proliferation, and differentiation of neutrophilic granulocyte precursor cells and functionally activates mature blood neutrophils. Among the family of colony-stimulating factors, G-CSF is the most potent inducer of terminal differentiation to granulocytes and macrophages of leukemic myeloid cell lines. White Myeloid Cells: Histology
NK: natural killer
TPO: thrombopoietin

Image by Lecturio. License: CC BY-NC-SA 4.0

Stages of platelet development

Development takes 1 week on average:

  1. Megakaryoblast:
    • Basophilic cytoplasm with a large, ovoid-, or kidney-shaped nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles
    • May have several nucleoli
  2. Megakaryocyte:
    • Giant cells Giant cells Multinucleated masses produced by the fusion of many cells; often associated with viral infections. In aids, they are induced when the envelope glycoprotein of the HIV virus binds to the CD4 antigen of uninfected neighboring T4 cells. The resulting syncytium leads to cell death and thus may account for the cytopathic effect of the virus. Giant Cell Arteritis (up to 150 μm in diameter)
    • Less basophilic
    • Long, branching cytoplasmic projections/extensions (proplatelets)
  3. Platelets: 
    • Results from megakaryocyte-cytoplasm fragmentation Fragmentation Chronic Apophyseal Injury
    • Fragmented-cell remains become apoptotic and removed by macrophages Macrophages The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood monocytes. Main types are peritoneal macrophages; alveolar macrophages; histiocytes; kupffer cells of the liver; and osteoclasts. They may further differentiate within chronic inflammatory lesions to epithelioid cells or may fuse to form foreign body giant cells or langhans giant cells. Innate Immunity: Phagocytes and Antigen Presentation.

Regulation

Table: Regulation
Cytokines Cytokines Non-antibody proteins secreted by inflammatory leukocytes and some non-leukocytic cells, that act as intercellular mediators. They differ from classical hormones in that they are produced by a number of tissue or cell types rather than by specialized glands. They generally act locally in a paracrine or autocrine rather than endocrine manner. Adaptive Immune Response/growth factors Activities Source
Stem cell factor Stem cell factor A hematopoietic growth factor and the ligand of the cell surface c-kit protein (proto-oncogene proteins c-kit). It is expressed during embryogenesis and is a growth factor for a number of cell types including the mast cells and the melanocytes in addition to the hematopoietic stem cells. Bone Marrow: Composition and Hematopoiesis (SCF) Stimulates all hematopoietic progenitor cells Bone-marrow stromal cells
Granulocyte-macrophage colony-stimulating factor ( GM-CSF GM-CSF An acidic glycoprotein of mw 23 kda with internal disulfide bonds. The protein is produced in response to a number of inflammatory mediators by mesenchymal cells present in the hemopoietic environment and at peripheral sites of inflammation. GM-CSF is able to stimulate the production of neutrophilic granulocytes, macrophages, and mixed granulocyte-macrophage colonies from bone marrow cells and can stimulate the formation of eosinophil colonies from fetal liver progenitor cells. GM-CSF can also stimulate some functional activities in mature granulocytes and macrophages. White Myeloid Cells: Histology) Stimulates myeloid progenitor cells Myeloid progenitor cells Stem cells derived from hematopoietic stem cells. Derived from these myeloid progenitor cells are the megakaryocytes; erythroid cells; myeloid cells; and some dendritic cells. Acute Myeloid Leukemia Endothelial cells, T cells T cells Lymphocytes responsible for cell-mediated immunity. Two types have been identified – cytotoxic (t-lymphocytes, cytotoxic) and helper T-lymphocytes (t-lymphocytes, helper-inducer). They are formed when lymphocytes circulate through the thymus gland and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen. T cells: Types and Functions
Thrombopoietin (TPO) Stimulates thrombopoiesis Kidney, liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy
Interleukin-3 (IL-3) Mitogen for all granulocyte and megakaryocyte-erythrocyte progenitor cells T helper cells

Clinical Relevance

  • Thrombocytopenia Thrombocytopenia Thrombocytopenia occurs when the platelet count is < 150,000 per microliter. The normal range for platelets is usually 150,000-450,000/µL of whole blood. Thrombocytopenia can be a result of decreased production, increased destruction, or splenic sequestration of platelets. Patients are often asymptomatic until platelet counts are < 50,000/µL. Thrombocytopenia: The patient presents with circulating platelets in the bloodstream below normal levels (< 150,000 platelets/µL).
  • Von Willebrand disease Von Willebrand disease Von Willebrand disease (vWD) is a bleeding disorder characterized by a qualitative or quantitative deficiency of von Willebrand factor (vWF). Von Willebrand factor is a multimeric protein involved in the plate adhesion phase of hemostasis by forming a bridge between platelets and damaged portions of the vessel wall. Von Willebrand Disease ( vWD vWD Von Willebrand disease (vWD) is a bleeding disorder characterized by a qualitative or quantitative deficiency of von Willebrand factor (vWF). Von Willebrand factor is a multimeric protein involved in the plate adhesion phase of hemostasis by forming a bridge between platelets and damaged portions of the vessel wall. Von Willebrand Disease): The most frequently inherited bleeding disorder among humans. Von Willebrand factor von Willebrand factor A high-molecular-weight plasma protein, produced by endothelial cells and megakaryocytes, that is part of the factor VIII/von Willebrand factor complex. The von Willebrand factor has receptors for collagen, platelets, and ristocetin activity as well as the immunologically distinct antigenic determinants. It functions in adhesion of platelets to collagen and hemostatic plug formation. The prolonged bleeding time in von Willebrand diseases is due to the deficiency of this factor. Hemostasis (vWF) allows platelet aggregation Aggregation The attachment of platelets to one another. This clumping together can be induced by a number of agents (e.g., thrombin; collagen) and is part of the mechanism leading to the formation of a thrombus. Coagulation Studies and contributes to the formation of fibrin Fibrin A protein derived from fibrinogen in the presence of thrombin, which forms part of the blood clot. Rapidly Progressive Glomerulonephritis clots. Different types of vWD vWD Von Willebrand disease (vWD) is a bleeding disorder characterized by a qualitative or quantitative deficiency of von Willebrand factor (vWF). Von Willebrand factor is a multimeric protein involved in the plate adhesion phase of hemostasis by forming a bridge between platelets and damaged portions of the vessel wall. Von Willebrand Disease (types 1, 2, and 3) are based on qualitative or quantitative defects in vWF. The condition may also be acquired (e.g., lupus and myeloproliferative disorders). 
  • Essential thrombocythemia Essential thrombocythemia Essential thrombocythemia (ET) is a type of myeloproliferative neoplasm characterized by the clonal thrombocytosis linked to somatic mutations involving Janus kinase 2 (JAK2), calreticulin (CALR), and myeloproliferative leukemia virus oncogene (MPL). Patients can be asymptomatic or present with vasomotor symptoms. Essential Thrombocythemia (ET): a myeloproliferative neoplasm characterized by the clonal thrombocytosis Clonal Thrombocytosis Essential Thrombocythemia linked to somatic mutations involving JAK2, CALR, and MPL oncogene. The presentation can be complicated by thrombohemorrhagic events, and progression to myelofibrosis and acute myeloid leukemia Acute Myeloid Leukemia Acute myeloid leukemia (AML) is a hematologic malignancy characterized by the uncontrolled proliferation of myeloid precursor cells. Seen predominantly in older adults, AML includes an accumulation of myeloblasts and a replacement of normal marrow by malignant cells, which leads to impaired hematopoiesis. Acute Myeloid Leukemia. The diagnosis is by laboratory finding of thrombocytosis, bone-marrow biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma, and genetic studies. Treatment aims to reduce platelet counts Platelet counts The number of platelets per unit volume in a sample of venous blood. Coagulation Studies with cytoreductive agents ( hydroxyurea Hydroxyurea An antineoplastic agent that inhibits DNA synthesis through the inhibition of ribonucleoside diphosphate reductase. Antimetabolite Chemotherapy) and decrease thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus with aspirin Aspirin The prototypical analgesic used in the treatment of mild to moderate pain. It has anti-inflammatory and antipyretic properties and acts as an inhibitor of cyclooxygenase which results in the inhibition of the biosynthesis of prostaglandins. Aspirin also inhibits platelet aggregation and is used in the prevention of arterial and venous thrombosis. Nonsteroidal Antiinflammatory Drugs (NSAIDs) and systemic anticoagulation Anticoagulation Pulmonary Hypertension Drugs.

References

  1. Italiano Jr., J.E., Whiteheart, S.W., Bray, P.F., Li, Z., Coller, B.S., Smyth, S.S. (2021). Platelet morphology, biochemistry, and function. Kaushansky K., Prchal J.T., Burns L.J., Lichtman M.A., Levi M., Linch D.C. (Eds.), Williams Hematology, 10e. McGraw-Hill. https://accessmedicine.mhmedical.com/content.aspx?bookid=2962&sectionid=252535907
  2. Kaushansky K. (2021). Megakaryopoiesis and thrombopoiesis. Kaushansky K., Prchal J.T., Burns L.J., Lichtman M.A., Levi M., Linch, D.C. (Eds.), Williams Hematology, 10e. McGraw-Hill. https://accessmedicine.mhmedical.com/content.aspx?bookid=2962&sectionid=252535799
  3. Mescher, A.L. (Ed.), (2021). Hemopoiesis. Junqueira’s Basic Histology Text and Atlas, 16e. McGraw-Hill. https://accessmedicine.mhmedical.com/content.aspx?bookid=3047&sectionid=255121548
  4. Shin, E.K., Park, H., Noh, J.Y., Lim, K.M., Chung, J.H. (2017). Platelet Shape Changes and Cytoskeleton Dynamics as Novel Therapeutic Targets for Anti-Thrombotic Drugs. Biomolecules & Therapeutics, 25(3), 223–230. https://doi.org/10.4062/biomolther.2016.138
  5. Twomey, L., Wallace, R., Cummins, P., Degryse, B., Sheridan, S., Harrison, M., Moyna, N., Meade-Murphy, G., Navasiolava, N., Custaud, M., Murphy, R. (2018). Platelets: From Formation to Function, Homeostasis-An Integrated Vision, Fernanda Lasakosvitsch and Sergio Dos Anjos Garnes, IntechOpen. https://www.intechopen.com/books/homeostasis-an-integrated-vision/platelets-from-formation-to-function

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