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Introduction to stem cell
- 2. DEFINITION • A cellthat has the ability to continuously divide and differentiate (develop) into various other kind(s) of cells/tissues. • the body is made up of about 200 different kinds of specialised cells such as muscle cells, nerve cells, fat cells and skin cells. • all cells in the body come from stem cells. • a stem cell is a cell that is not yet specialised. • the process of specialisation is called differentiation. • once the differentiation pathway of a stem cell has been decided, it can no longer become another type of cell on its own.
- 3. STEM CELL HISTORY 1998- Researchers first extract stem cells from human embryos 1999 - First Successful human transplant of insulin-making cells from cadavers 2001 - President Bush restricts federal funding for embryonic stem-cell research 2002 - Juvenile Diabetes Research Foundation International creates $20 million fund-raising effort to support stem-cell research 2002 - California stem cell research 2004 - Harvard researchers grow stem cells from embryos using private funding 2004 - Ballot measure for $3 Billion bond for stem cells
- 4. STEM CELL CHARACTERISTICS ‘Blank cells’ (unspecialized) Capable of dividing and renewing themselves for long periods of time (proliferation and renewal) Have the potential to give rise to specialized cell types (differentiation)
- 6. TYPES OF STEMCELL 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
- 7. KINDS OF STEMCELL 1. Embryonic stem cells come from a five to six-day-old embryo. They have the ability to form virtually any type of cell found in the human body. 2. Embryonic germ cells are derived from the part of a human embryo or foetus that will ultimately produce eggs or sperm (gametes). 3. Adult stem cells are undifferentiated cells found among specialised or differentiated cells in a tissue or organ after birth. Based on current research they appear to have a more restricted ability to produce different cell types and to self-renew.
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- 9. WHY ARE STEMCELLS SPECIAL? Stem cells can: 1. self-renew to make more stem cells. 2. differentiate into a specialised cell type. Embryonic stem cells (pluripotent) Stem cells that can become many types of cells in the body are called pluripotent Tissue stem cells (multipotent) Stem cells that can become only a few types of cells are called multipotent
- 10. TISSUE STEM CELLS •often known as adult stem cells • also includes stem cells isolated from fetal and cord blood • reside in most tissues of the body where they are involved in repair and replacement • generally very difficult to isolate • already used to treat patients (haematological malignancies, diseases of the immune system) Bone marrow Kidney Lung
- 11. 8-cell blastocystfertilised egg 2-cellegg Day 0Day 1 Day 2 Day 3 Day 6 • Donated excess IVF embryos Images from www.advancedfertility.com Where do embryonic stem cells come from? Inner cell mass
- 12. Embryonic stem cells •derived from donated IVF embryos • can be grown indefinitely in the laboratory in an unspecialised state • retain ability to specialise into many different tissue types – know as pluripotent • can restore function in animal models following transplantation Human embryonic stem cells can become any cell in the body including these beating heart cells human embryonic stem cells
- 13. INDUCED PLURIPOTENT STEMCELLS • derived from adult cells in 2007 - very recent discovery! • can be grown indefinitely in culture in an undifferentiated state • similar properties to embryonic stem cells as can differentiate into many different tissue types – pluripotent • can create stem cells directly from a patient for research Induced change in gene expression pluripotent stem cells Starting cells from donor tissue iPS Cells
- 14. WHAT MAKES STEMCELLS SO VALUABLE? Cell Therapy Research New Drugs Pluripotent stem cells Tissue stem cells No one stem cell type fits all applications. Research must continue using all types of stem cells.
- 17. APPLICATIONS Disease • Diabetes,Spinal cord injury, Parkinson’s disease, heart disease Genetic based Disease • Cystic fibrosis, Huntington’s
- 18. CHALLENGES TO STEMCELL/CLONING RESEARCH 1. Stem cells need to be differentiated to the appropriate cell type(s) before they can be used clinically. 2. Recently, abnormalities in chromosome number and structure were found in three human ESC lines. 3. Stem cell development or proliferation must be controlled once placed into patients. 4. Possibility of rejection of stem cell transplants as foreign tissues is very high. 5. Contamination by viruses, bacteria, fungi, and Mycoplasma possible. 6. The use of mouse “feeder” cells to grow ESC could result in problems due to xenotransplantation.
- 19. UNKNOWNS IN STEMCELL/CLONING RESEARCH • It is uncertain that human embryonic stem cells in vitro can give rise to all the different cell types of the adult body. • It is unknown if stem cells cultured in vitro (apart from the embryo) will function as the cells do when they are part of the developing embryo
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