Week 10 - Stem Cells and Applications

Week 10 - Stem Cells and Applications

1. Properties of a Stem Cell

   • When it divides, each daughter cell has a choice:
     • Remain a stem cell; SELF-RENEW
     • Begin the pathway to differentiate; DIFFERENTIATED CELLS
   • It is not differentiated (specialised)

2. Where do Stem Cells come from?

   • Adult Tissues
   • Embryonic/Fetal
     • Amniotic Fluid - Stem Cell
     • Umbilical Cord Blood - Stem Cell
     • Blastocyst - Embryonic Stem Cell

3. Potency

   • Multipotent
     • Fetal Stem Cells
     • Cord Blood Stem Cells
     • Adult Stem Cells
   • Pluripotent
     • Induced-Pluripotent Stem Cells
     • Embryonic Stem Cells
   • Totipotent
     • Fertilised Egg

4. Multipotent Stem Cells

   • Found in both fetal and adult tissues
   • Restricted potency
   • Associated with niches within organ tissues to regulate stem cell maintenance and differentiation

5. Hematopietic Stem Cells

   • Derived from bone marrow
   • Give rise to all blood cell types
   • A lot of self-renewal in the progenitor stages

6. Mesenchymal Stem Cells

   • Derived from bone marrow, adipose tissue, cartilage
   • Generates bone, adipose and cartilage cells
   • Used in stem cell therapies (regulated and unregulated)

7. Neural Stem Cells

   • Derived from fetal tissue
   • Gives rise to both neurons and Glia

8. Adult Neural Stem Cells

   • SubGranular Zone (SGZ) Niche
     • SGZ astrocytes divide to generate intermediate precursor cells (type D) which progressively generate more differentiated cells; D1, D2, D3 which mature into granule neurons
   • SubVentricular Zone (SVZ) Niche
     • Region in the brain where neural stem cells still exist and self-renew
     • B (Glia) cells can self-renew or differentiate into transit amplifying cells (TA) which then differentiate into neuroblasts
     • Neuroblasts migrate along the Rostral Migratory Stream to the Olfactory Bulb where they differentiate into neurons
     • In the case of injury, neuroblasts leave the migratory system and migrate to the site of injury where they differentiate to form scar tissue

9. Stem Cell Niche

   • Niche can be in vivo or in vitro stem cell microenvironments
   • Describes the microenvironment in which stem cells are found and which interacts with stem cells to regulate stem cell fate

10. Culturing ES Cells

    • Cultures on mouse/human fibroblast feeder layers OR a specialised extracellular matirx
    • Different culture requirements for mouse and human ES cells

11. Pluripotency: Derivation of Cell Types from Primary 3 Germ Layers

    • Endoderm
      • Pancreatic cell
      • Thyroid cell
      • Lung cell
    • Ectoderm
      • Skin cells
      • Neuron (brain)
      • Pigment cell
    • Mesoderm
      • Cardiac muscle
      • Skeletal muscle
      • Tubule cell (kidney)
      • Red blood cell
      • Smooth muscle

12. Test for Pluripotent Stem Cells

    • Directed differentiation to 3 germ layers
    • Cultures of embryoid bodies
    • Differentiate spontaneously in vitro into derivatives of the 3 germ layers

13. ES and iPS Cells

    • Similar
      • Morphology
      • Age-related telomeres
      • Surface markers
      • Overall gene expression
    • Differences
      • Takes a long time to make iPS cells and very few reprogrammed
      • Need human oocytes to derive human ES cells