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Stem Cells and Stem Cell Therapy.pdf

  1. 1. Stem Cells and Stem Cell Therapy
  2. 2. Cell – A complex Organ  Cell Theory: all living things are composed of one or more cells……..  Cells fall into two basic types prokaryotic and eukaryotic.  Prokaryotic cells are smaller and lack much of the internal compartmentalizin and complexity of eukaryotic cells.
  3. 3. Diversity of Human Cells Adult humans consist of more than 200 kinds of cells. They are nerve cells (neurons), muscle cells (myocytes), skin (epithelial) cells, blood cells (erythrocytes, monocytes, lymphocytes, etc.), bone cells (osteocytes), and cartilage cells (chondrocytes). cells essential for embryonic development but not incorporated into the body of the embryo, include the extra-embryonic tissues, placenta, and umbilical cord. All of these cells are generated from a single, totipotent cell, the zygote, or fertilized egg.
  4. 4. What Are Stem Cells? Stem cells are the raw material from which all of the body’s mature, differentiated cells are made. Stem cells give rise to brain cells, nerve cells, heart cells, pancreatic cells, etc.
  5. 5. One Cell - Several lineages
  6. 6. Features of Stem Cells 1. Stem Cells are very unique cells. 2. Stem Cells have the amazing ability to develop into several distinct cell types in the body. 3. Stem Cells can be used as a repair system for the body. 4. Stem Cells can theoretically divide without limit in a living organism in order to replenish various types of cells. 5. When a stem cell divides, each new cell has the potential to either remain a stem cell or become another type of cell with a more specialized function (i.e. a muscle cell, a red blood cell, a brain cell, etc.).
  7. 7. Sources of embryonic type stem cells * Embryos - Embryonic stem cells are obtained by harvesting living embryos which are generally 5-7 days old. The removal of embryonic stem cells invariably results in the destruction of the embryo. * Fetuses - Another kind of stem cell, called an embryonic germ cell, can be obtained from either miscarriages or aborted fetuses.
  8. 8. Sources of adult type stem cells  Umbilical Cords, Placentas and Amniotic Fluid - Adult type stem cells can be derived from various pregnancy-related tissues.  Adult Tissues - In adults, stem cells are present within the bone marrow, liver, epidermis, retina, skeletal muscle, intestine, brain, dental pulp and elsewhere.  Cadavers - Neural stem cells have been removed from specific areas in post-mortem human brains as late as 20 hours following death.
  9. 9. Types of Stem cells
  10. 10. Totipotent stem cells 1. The fertilized egg is said to be totipotent from the Latin totus, meaning “entire”.. 2. It has the potential to generate all the cells and tissues that make up an embryo. 3. It supports embryonic development in utero.
  11. 11. Pluripotent stem cells Pluripotent stem cells are descendants of the totipotent stem cells of the embryo. These cells develop about four days after fertilization They can differentiate into any cell type, except for totipotent stem cells and the cells of the placenta.
  12. 12. Pluripotent stem cells “Pluri” is derived from the Latin plures means several or many. Thus, pluripotent cells have the potential to give rise to any type of cell.
  13. 13. Pluripotent stem cells  These cells cannot re-create a complete organism but differentiate to a large number of mature tissue types, for example, brain and muscle.
  14. 14. Multipotent stem cells Multipotent stem cells are descendents of pluripotent stem cells and antecedents of specialized cells in particular tissues. For example, hematopoietic stem cells, which are found primarily in the bone marrow, give rise to all of the cells found in the blood,including red blood cells, white blood cells, and platelets.
  15. 15. History of Adult Stem Cell Research  Since the 1970’s, bone marrow transplants have been used for treatment of Immunodeficiency disorder and leukemia.
  16. 16. History of Human Embryonic Stem Cell Research In 1998, James Thomson (University of Wisconsin-Madison) isolated cells from the inner cell mass of the blastocyst, and developed the first human embryonic stem cell line in culture. Isolate inner cell mass Culture cells Inner cell mass (forms fetus) Day 5-6 Blastocyst
  17. 17.  In 1998, James Thomson (University of Wisconsin-Madison) isolated cells from the inner cell mass of the early embryo, and developed the first human embryonic stem cell lines, History of Human Embryonic Stem Cell Research  In 1998, John Gearhart (Johns Hopkins University) derived human embryonic germ cells from cells in fetal gonadal tissue (primordial germ cells).  Pluripotent stem cell “lines” were developed from both sources
  18. 18. Embryonic stem (ES) cells  ES cells are found at the blastocyst stage, four to five days after the union of the sperm and egg, before the embryo implants in the uterus.
  19. 19. Day 1 In Vitro Fertilization
  20. 20. Day 1 In Vitro Development
  21. 21. Day 2 In Vitro Development
  22. 22. Day 2 In Vitro Development
  23. 23. Day 3 In Vitro Development
  24. 24. Day 4 In Vitro Development
  25. 25. Embryonic Stem Cells Day 5 In Vitro Development
  26. 26.  Specific regions of the embryo give rise to the specific organ systems  Ectoderm generates the outer layer of the embryo and produces the surface layer (epidermis) of the skin and forms the nerves  Endoderm becomes the innermost layer of the embryo and produces the digestive tube and its associated organs (including the lungs)  Mesoderm becomes sandwiched between the ectoderm and endoderm and generates the blood, heart, kidney, gonads, bones, and connective tissues.
  27. 27. Placenta a Source of Stem Cells  Placental stem cells, like umbilical cord blood and bone marrow stem cells, can be used to cure chronic blood-related disorders such as sickle cell disease, Thalasemia, and leukaemia.
  28. 28. Umbilical Cord Blood Stem Cell Transplant  Umbilical cord blood stem cell transplants are less prone to rejection than either bone marrow or peripheral blood stem cells. This is probably because the cells have not yet developed the features that can be recognized and attacked by the recipient's immune system
  29. 29. Kinds of Stem Cells Stem cell type Description Examples Totipotent Each cell can develop into a new individual Cells from early (1-3 days) embryos Pluripotent Cells can form any (over 200) cell types Some cells of blastocyst (5 to 14 days) Multipotent Cells differentiated, but can form a number of other tissues Fetal tissue, cord blood, and adult stem cells
  30. 30. What’s So Special About Stem Cells? They have the potential to replace cell tissue that has been damaged or destroyed by severe illnesses. They can replicate themselves over and over for a very long time. Understanding how stem cells develop into healthy and diseased cells will assist the search for cures.
  31. 31. Two Kinds of Stem Cells Embryonic (also called “pluripotent”) stem cells are capable of developing into all the cell types of the body. Adult stem cells are less versatile and more difficult to identify, isolate, and purify.
  32. 32. How Does Cell Therapy Work?  Stem cells can be used to generate healthy and functioning specialized cells, which can then replace diseased or dysfunctional cells.  It is similar to the process of organ transplantation only the treatment consists of transplanting cells instead of organs.
  33. 33. How Does Cell Therapy Work?  Bone marrow transplants are an example of cell therapy in which the stem cells in a donor's marrow are used to replace the blood cells of the victims of leukemia.  Cell therapy is also being used in experiments to graft new skin cells to treat serious burn victims, and to grow new corneas for the sight-impaired.  In all of these uses, the goal is for the healthy cells to become integrated into the body and begin to function like the patient's own cells.
  34. 34. What Diseases Can be Cured by Stem Cell Therapies  Any disease in which there is tissue degeneration can be a potential candidate for stem cell therapies
  35. 35. Major Progress in Several Important Health problems  Alzheimer’s disease  Parkinson’s disease  Spinal cord injury  Heart disease  Severe burns  Diabetes
  36. 36. Ethical debate  Harvesting ES cells destroys the blast cyst  “This is murder”  ES cell research requires human cells  Could create a commercial market for human cells  “This devalues life” Reproduced by permission of Dave Catrow and Copley News Service
  37. 37. Research on Stem Cells is progressing in spite of several restrictions