stem cells

• Zygote


  Fertilised egg
• Morula


  16 cell stage ~3-4 days after fertilisation
• Blastocyst


  5 days until implantation into uterus
• Gastrula


  Days 15 – 17
• Stem Cell


  A cell that is not differentiated itself but can undergo unlimited division to form other cells, which either remain as stem cells or differentiate to form specialised cells
• Stem Cells


  • They have the potential to divide and become either more stem cells or specialised cells
• Stem Cell Niche


  The specific micro environment that stem cells live in, made of specialized cell structures that protect the stem cell and regulate its growth/replication
• Stem Cells


  • Are capable of self-renewal
  • Can replicate themselves as new stem cells, as well as, differentiating into distinct cell types
  • Certain stem cells are able to divide indefinitely in order to replace cells
• Embryonic Stem Cells


  The undifferentiated or relatively undifferentiated cells of embryos, from the zygote to blastocyst stage
• Adult Stem Cells


  Present in small numbers in some adult tissues, remain as stem cells throughout an individual's life, give rise to only a limited range of cells, purpose is repair and regeneration of damaged and aged tissues
• Totipotent


  Capable of giving rise to any cell type or even another embryo (Zygote to 16 cell Morula stage)
• Pluripotent


  Can differentiate into any of the three germ layers: Endoderm, Mesoderm, Ectoderm (Blastocyst stage and also primordial germ cells that produce gametes)
• Multipotent


  Have the ability to give rise to multiple, but limited, cell types
• Unipotent


  Can only differentiate into one cell type found in a specific tissue but can divide repeatedly
• Induced Pluripotent Stem Cells (iPSC)

  Adult stem cells that are genetically programmed to become embryonic stem cells again, thus becoming pluripotent
• Advantages and Disadvantages


  • Embryonic Stem Cells
  • Adult Stem Cells
  • Induced Pluripotent Stem Cells
• Stem cells must be able to replicate themselves in cultures within a laboratory
• Stem cells must be able to differentiate into the particular cells required to treat the disease or disorder
• Stem cells must not remain as self-renewing stem cells with the potential to grow out of control
• The immune system must not reject the stem cells or tissue created from stem cells
• Research into the possible uses of stem cells is continuing
• To be used in a range of treatments eg- bone marrow, cord blood etc.
• Most likely conditions to be effectively treated by stem cell therapy are those where a small and defined cell population is damaged