Presentation on theme: "Adult Stem Cells Stem Cells, Bone Marrow and Blood"— Presentation transcript:
1 Adult Stem Cells Stem Cells, Bone Marrow and Blood Potent Biology: Stem Cells, Cloning and RegenerationJuly 10-13, 2007
2 Stem CellsEmbryonic – undifferentiated cells from the embryo that have the potential to become a wide variety of specialized cell typesZygote (totipotent)Morula (totipotent-pluripotent)Blastocyst (pluripotent)Inner Cell Mass (ICM) (pluripotent)Gastrula (multipotent)
3 Adult Stem Cells What are adult stem cells? Somatic cells that are unspecializedDepending on the tissue, the cells have different properties.What is the role of adult stem cells?Maintain and repair the bodies tissueStem cells share 2 characteristicsProliferate - capable of long-term self-renewalDifferentiate into mature cellsProgenitor cellsPrecursor cellsAdult stem cells are capable of self-renewal and give rise to daughter cells that are specialized to form the cell types found in the original body part.
4 Stem CellsWhere are they found?InfantsAdultsBone marrow (BM)
5 Bone Marrow, Stem Cells and Blood Hiroshima and Nagasaki 1943RadiationCompromised hematopoietic systemCouldn’t produce white blood cells (WBC’s)Couldn’t produce plateletsMouse studiesIrradiation to whole body resulted in death of the miceBM cells from normal mouseinjected into lethally irradiatedmicePrevented death frombone marrow failureMcColloch and Till; Radiation Research 13, ; 1960
6 Why Did This Bone Marrow Transplant Work? Bone Marrow is the site of blood cell (red blood cells, white blood cells, and platelets) production… Hematopoiesis.
7 Hematopoiesis: Stem Cell Hierarchy Process begins with Hematopoietic Stem Cells (HSCs) capable ofProliferationDifferentiationDifferentiation of HSCs follows 2 cell lines.MyeloidLymphoidHematopoieticStem Cell
8 Hematopoiesis: Stem Cell Hierarchy Cells in either line differentiate along an irreversible succession or hierarchy of precursor cellsEach descendent cell has progressively limited potential.
9 Hematopoiesis: Stem Cell Hierarchy How do HSC’s know which pathway to follow or which cell to become?Differentiation is directed by signal molecules (growth factors known as cytokines and interleukins)Bone marrow stromal cells are the major source of these growth factors.Bm CONTains 3 sc POPULATions HSCs, StROMAL CELLS, AND ENDOThelial progenitOR CELLS
10 Hematopoiesis: Stem Cell Hierarchy Cytokines are a family of proteins that direct differentiation of a particular lineage.Combinations of cytokines can stimulateProliferation and/orDifferentiation
12 SummaryThe development of different blood cell types from bone marrow stem cells is an example of how the body uses adult stem cells.Different types of blood cells (RBC, WBC, platelets) have very different functions.All types of human blood cells differentiate from bone marrow stem cells.The differentiation of human blood cells is hierarchical and irreversible.An early division in the differentiation of human blood cells is along two (myeloid and lymphoid) precursor stem cell lines.Differentiation is directed by signaling moleculesThe signaling molecule(s) to which a stem cell is exposed determines which blood cell it becomes.