All are generated ultimately from a common stem cell located in the bone marrow

All are generated ultimately from a common stem cell

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All are generated ultimately from a common stem cell located in the bone marrow, as well as in umbilical cord blood and placental tissue Bone marrow gives rise to all the blood cell and stromal cell types: Myeloid (monocytes and macrophages, neutrophils, basophils, eosinophils, erythrocytes, megakaryocytes/platelets, dendritic cells) Lymphoid (T-cells, B-cells, NK-cells) Other Mesenchymal cells such as Osteoclasts, Adipocytes etc…
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Red Blood Cells Are All Alike; White Blood Cells Can Be Grouped in Three Main Classes
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Red Blood Cells Are All Alike; White Blood Cells Can Be Grouped in Three Main Classes
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The Production of Each Type of Blood Cell in the Bone Marrow Is Individually Controlled WBCs function in tissues outside of blood Inflammation or injury attracts WBCs to the affected region Damaged tissues secrete chemokines that attract WBCs towards them Other signal molecules escape into the blood and stimulate the bone marrow to produce more WBCs and release them into the blood stream Similarly in anemic conditions increase in RBCs occur
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Bone Marrow Contains Multipotent Hematopoietic Stem Cells, Able to Give Rise to All Classes of Blood Cells Complex arrangement of blood cells, very difficult to identify stem cells So, how were stem cells first identified?
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Bone Marrow Contains Multipotent Hematopoietic Stem Cells, Able to Give Rise to All Classes of Blood Cells Sort cells taken from bone marrow based on cell surface markers. How? Transfuse different cell fractions back into irradiated mice The fraction that rescues the mice must contain hematopoietic stem cells Helps in obtaining pure stem cell populations. About 1 cell in 50000-100000 THIS IS ENOUGH!! A single cell injected is sufficient to reconstitute the entire hematopoietic system!! A similar procedure is used in the treatment of Leukemia in human patients by bone marrow transplantation
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Bone Marrow Contains Multipotent Hematopoietic Stem Cells, Able to Give Rise to All Classes of Blood Cells Commitment happens before ceasing proliferation Therefore, committed progenitors can go through many rounds of cell division to amplify the number of specialized cells
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Stem Cells Depend on Contact Signals From Stromal Cells Hematopoietic stem cells depend on signals from their niche Losing contact with the niche can lead to loss of stem cell potential The committed progeny do not depend on the niche to the same degree as the stem cells Therefore, these cells can be cultured in vitro by adding factors called colony stimulating factors (CSFs) to identify their developmental pathway Eg: Erythropoietin for erythrocyte development
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Mesenchymal stem cells (MSCs) MSC bone marrow committed progenitors Bone (osteoblasts) Cartilage (chondrocytes) Fat (adipocytes) specialized cells These stem cells will differentiate into: cartilage cells (chondrocytes) muscle cells (myocytes) fat cells (adipocytes) tendons, ligaments, and connective tissue (epithelial cells including osteoblasts) These cells are located throughout the body Bone marrow, fat, and cord blood are easiest to isolate
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New evidence on bone marrow stem cells?
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