Lesson 2 - Stem Cells

Question 1

When do Symmetric and Asymmetric cell division occur?

Answer 1

• during development and in adult stem cells

Question 2

What happens in symmetrical cell division (primary cells/ cells used in culture) ?

Answer 2

• one cell divides into two and those two cells are identical

Question 3

How does cell division occur in stem cells?

Answer 3

• divides into two cells that are unique from the original cell or one the same/ one unique
• important for cells to specialize
• important for giving rise to fresh cells to renew the tissue in adult stem cells
• occurs more in stem cells in embryonic development or in adult tissues

Question 4

What is a progenitor cell

Answer 4

• the two cells that divide from a stem cell can either be a differentiated cell or a progenitor cell
• progenitor cells give rise to differentiated cells, differentiated cells have reached their final state and function in their designated part of the body

Question 5

Why is asymmetric division important

Answer 5

• asymmetric division renews stem cells populations or gives rise to multitudes of different types of cells

Question 6

What are embryonic stem cells?

Answer 6

• pluripotent cells and can be grown indefinitely in culture under appropriate conditions

Question 7

What is a blastocyst?

Answer 7

• clustering of cells (inner cell mass)
• pipettes take out the inner cell mass and put them onto a plate of fibroblast cells
• fibroblast secrete factors and cytokines to ensure the survival of the inner cell mass cells
• inner cell mass cells have a high number of pluripotent stem cells

Question 8

How are the embryonic stem cells in culture established?

Answer 8

• inner cell mass cells are put onto the fibroblast with varying pluripotentcy
• cells divide and form colonies
• colonies are put onto a fresh feeder and grow them in suspension cultures
• the ones that go back to the embryonic state are the ones that we want

Question 9

What are adult stem cells required to do ?

Answer 9

• maintain and repair tissue

- self renew and differentiate

Question 10

What happens with the stem cells in the intestine?

Answer 10

• found in the crypts
• adult stem cells divide and give rise to another stem cell/ differentiate themselves
• excessive division/differentiation results in cells piling on top of one another and pushing towards the top
• they become functional epithelial intestinal cells which are important for absorbing nutrients from the lumen
• at the top they die

Question 11

How can pluripotent stem cells be obtained from differentiated normal cells?

Answer 11

• by taking differentiated cells and introducing transcription factors which are highly expressed in ES cells
• taking the transcription factors and overexpressing them in differentiated cells

Question 12

What is the Yamanaka factor?

Answer 12

• taking differentiated cells and reverting them back to a pluripotent state

Question 13

What are the uses of iPS cells?

Answer 13

• we can take cells from an individual and reprogram them to induced pluripotent stem cells and differentiate the cells to a certain cell type to help repair a certain tissue that’s diseased or has died off - they wont be rejected
• taking cells form an individual, reprogramming them by genetic means and using them for differentiation for repairing damaged tissue

Question 14

What are the genes that are the characteristics of ES cells?

Answer 14

• Oct4, Sox2, Klf4, c-Myc

- c-Myc is expressed in cancer cells and dysregulates cell cycle which could lead to a transformed phenotype

Question 15

What are two ways that you can help a patient that has loss of neurons, using yamanaka factors?

Answer 15

1) - take the skin from the person, culture them and introduce Yamanaka factors and turn them ints iPS
- stem cells could be genetically corrected using genome editing technology
- repair mutation by taking corrected cells and differentiate them into healthy neurons, and replenish the lost neurons
2) - take iPS cells, differentiate them into neurons, then try to figure out whats wrong
- take gen. corrected cells and differentiate them into neurons and compare them to the patient derived neurons
- when correcting mutations by gen. editing, you can see how the healthy cells do better than the diseased cells

Question 16

Primary cell - division, differentiation capability and therapeutic potential?

Answer 16

• symmetric, differentiated, limited

- straight from the tissue

Question 17

transformed cell - division, differentiation capability, therapeutic potential?

Answer 17

• symmetric, differentiated, no

- HeLa calls, artificially introduced oncogene

Question 18

ES cell - division, differentiation capability, therapeutic potential?

Answer 18

• sym/assym, pluripotent, restricted by ethical considerations (could result in rejection)

Question 19

AS cell - division, differentiation capability, therapeutic potential?

Answer 19

• symmetric/asymm, multipotent, yes
• have been used for bone marrow transplant
• important for renewal

Question 20

Induced pluripotent cells - division, differentiation capability, therapeutic potential?

Answer 20

• symm/asymm, pluripotent, yes but safety concerns

- division is dependant on cytokinins, safety concerns with therapy

Question 21

What are pluripotent cells?

Answer 21

• give rise to 3 germ layers, endo, meso and ecto, give rise to all tissues in our body