Day 14, Lecture 2 (Sept 9): Human Development: Stem Cells

Question 1

New Stem Cell Biology

Answer 1

• New Stem Cell Biology
  
  • developmental Biology
  • presence of adult stem cells
  • Differentiation occurring in adult
• Cancer
  
  • Cancer stem cells
• Regenerative Medicine
  
  • Tissues/cells for transplantation
  • Tissues/cells for testing therapeutics or toxicity testing
  • Study cell differentiation

Question 2

Answer 2

Question 3

Definition of Stem Cell

Answer 3

• Self-renewing
  
  • when it divides
    
    • one cell retains undifferentiated character (stemness)
    • Second cell can undergo one or more paths of differentiation

Question 4

Symmetrical versus non-symmetrical division

Answer 4

Question 5

Potential of Progenitor Cells

Answer 5

Question 6

Transit Amplifying Cell

Answer 6

• Different than stem cell
• Not capable of unlimited self-renewal
• Has the capacity to divide only a few times before differentiating

Question 7

Differences between adult and embryonic stem cells

Answer 7

Question 8

Adult Stem Cells

Answer 8

• Very difficult to grow in culture

Question 9

Question 10

Define Stem cell niche

Answer 10

• During development special environment set aside for stem cell to divide
  
  • examples:
    
    • hematopoetic stem cell niche
    • Epidermal skin cell niche
    • Intestinal cell niche

Question 11

Control differentiation of stem cells

Answer 11

• combination of paracrine factors and extracellular matrix produced by niche cells
• Too much differentiation depletes stem cells and promotes aging and decay

Question 12

Why is it diffucult to grow adult stem cells in culture

Answer 12

They need a very specific niche

Question 13

Mesenchymal Stem Cells

Answer 13

• Found in numerous tissues
  
  • bone marrow
  • fat
  • muscle
  • thymus
  • dental pulp
  • umbilical cord (note most of the stem cells in cord blood are hematopoetic stem cells)
• Have more potenital than most other adult stem cells
  
  • multipotential
• in vitro can form:
  
  • bone
  • cartilage
  • muscle
  • fat
  • neurons
• not yet know range of plasticit in vivo
  
  • major role may be to produce paracrine factors that aid adult stem cells to divide and repair tissue

Question 14

New perspectives on Organogenis

Answer 14

Question 15

Embryonic Stem Cells

Answer 15

• Derived from inner cell mass of blastocyst
  
  • Pluripotent
    
    • can differentiate into all types of adult cells, tissues and organs
    • can differentiate into all three germ layers
  • Obtain blastocyst needed for isolation of embryonic stem cels from frozen in vitro fertilization embryos donated by parents
  • Grow in culture and can be maintained for a long time

Question 16

Answer 16

Question 17

Potential Clinical Use for Embryonic Stem Cells

Answer 17

Question 18

If you inject a patient with embryonic stem cells what will happen

Answer 18

you will end up a teratomma (a tumor with all 3 germ layers)

Question 19

Answer 19

Question 20

Induced Pluripotent Stem Cells (iPS)

Answer 20

• Adult differentiated cells can be transfected with transcription factors present in embryonic stem cells
• Differentiated cell will form pluipotent embryonic stem cell
• iPs cells are different than ES cells
  
  • During differentiation genetic material is modified by epigenetic changes
  • Epigenetic changes remain even after differentiated cell is induced to be pluripotential
  • Unclear effect this will have upon ability of iPS cells to differentiate and form normal cells, tissues, and organs

Question 21

Question 22

Answer 22

Question 23

If you put Mesenchymal cells into a person what will happen

Answer 23

• They will home in to damaged tissue but do not participate in repair
• may provide the enviroment to assist adult stem cells in repair

Question 24

Answer 24

Question 25