WHAT ARE STEM CELLS? They are unspecialized cells with 2 defining properties: 1] Self renewal 2] Unlimited potency STEM CELLS EMBRYONIC ADULT / SOMATIC EMBRYONIC STEM CELLS Are the inner mass cells of the blastocyst Derived from embryos that develop from eggs that have been fertilized in vitro Are pluripotent ie. can become any cell type By directing their differentiation into specific cell types – may be able to treat certain disease such as Parkinson's disease, diabetes, traumatic spinal cord injury, Purkinje cell degeneration, Duchenne's muscular dystrophy, heart disease, and vision and hearing loss (Kondziolka, 2002; Daley et al., 2003; Bethesda1, 2008) ADULT STEM CELLS Undifferentiated cells found in adult tissues or organs Can replicate and differentiate to form specialized cells of a tissue or organ Found in the brain, bone marrow, peripheral blood, blood vessels, skeletal muscle, skin and liver (Bethesda2, 2008) By manipulating them into generating specific cell types – could be used for potential treatments such as replacing the dopamine- producing cells in the brains of Parkinson's patients, developing insulin-producing cells for type I diabetes and repairing damaged heart muscle following a heart attack with cardiac muscle cells (Daley et al., 2003; Bethesda2, 2008) NORMAL DIIFERENTIATION PATHWAYS OF ADULT STEM CELLS (Bethesda2, 2008) Hematopoietic stem cells – give rise to all types of blood cells Bone marrow stromal cells / mesenchymal stem cells – gives rise to bone cells, cartilage cells, fat cells and other types of connective tissue cells Neural stem cells – give rise to nerve cells and non-neuronal cells Epithelial stem cells – give rise to absorptive cells, goblet cells and enteroendocrine cells INORDER FOR TISSUE REGENERATION TO TAKE PLACE, WE NEED STEM CELLS TO (Bethesda3, 2008): Multiply extensively and generate sufficient amounts of tissue Differentiate into the desired cell type Survive in the recipient after transplant Integrate into the surrounding tissue after transplant Function appropriately Not harm the recipient in any way Bethesda1 , M.D.: National Institutes of Health, U.S. Department of Health and Human Services. 2008. Stem cell information - Stem Cell Basics: What are embryonic stem cells? [online]. Available: http://stemcells.nih.gov/info/basics/basics3 [accessed 25 September 2008]. Bethesda2 , M.D.: National Institutes of Health, U.S. Department of Health and Human Services. 2008. Stem cell information - Stem Cell Basics: What are adult stem cells? [online]. Available: http://stemcells.nih.gov/info/basics/basics4 [accessed 25 September 2008]. Bethesda3 , M.D.: National Institutes of Health, U.S. Department of Health and Human Services. 2008. Stem cell information - Stem Cell Basics: What are the potential uses of human stem cells and the obstacles that must be overcome before these potential uses will be realized? [online]. Available: http://stemcells.nih.gov/info/basics/basics6 [accessed 25 September 2008]. Daley, G.Q., Goodell, M.A., Snyder, E.Y. 2003. Realistic prospects for stem cell therapeutics. American Society of Hematology. 398-418. Kondziolka, D., Wechsler, L., Achim, C. 2002. Neural transplantation for stroke. Journal of Clinical Neuroscience. 9, 225-230.