L2 6 Mar 2019

Question 1

stem cell

Answer 1

• self renewal
• differentiate into many different cell types

Question 2

stem cell status in adults

Answer 2

most are quiescent, there are active ones in the gut though

Question 3

blastocyst

Answer 3

used to derive pluripotent stem cells –> from inner cell mass

Question 4

purpose of dissecting inner cell mass out of blastocysts

Answer 4

can create stem cell lines, used for cloning

Question 5

what is the significance of which germ layer a stem cell comes from?

Answer 5

usually cells from the same germ layer can be “converted” (in some way) into each other

Question 6

major stem cell types

Answer 6

• embryonic stem cells
• embryonic germ cells
• adult stem cells
• umbilical cord and placenta stem cells

Question 7

stem cell niches (in tissues and organs)

Answer 7

stem cells naturally exist in a microenvironment, which acts as maintenance and supports normal function

Question 8

examples of stem cell niches

Answer 8

• haematopoietic stem cells are surrounded by stromal stem cells
• brain stem cells are in the subventricular zone –> close to ependymal cells and close to blood vessels
• skin stem cells in hair follicle bulge, called “bulge stem cells”

Question 9

microglia

Answer 9

macrophage like cells in the brain

Question 10

stem cell activation in the brain

Answer 10

1. microglial activation
2. activates astrocytes
3. activates neural stem cells
4. activates neural stem cells, however this won’t lead to a complete recovery due to the fact that we have limited stem cells
5. always leads to some scarring (glial scar)

Question 11

SCNT

Answer 11

• asexual reproduction by somatic cell nuclear transfer
• no sperm
• transfers nucleus from mature cell to donor egg
• requires stimulus to begin dividing
• *functionally different* from regular egg

Question 12

stem cell therapies

Answer 12

“autologist transplants” taking patient’s own cells and putting them back into the patient after cloning or something

Question 13

molecular reprogramming

Answer 13

goal: manipulate somatic cell’s potency (increase it)

Question 14

factors that can reverse normal adult cell to iPS (induced pluripotent cells)

Answer 14

Oct 3/4, Sox2, c-Myc, Klf4

Question 15

adult stem cell

Answer 15

• typically in or near their tissue
• capable of giving rise to functional cells in their tissue
• typically found in tissues with regular turnover
• decrease in both number and activity as you age

Question 16

embryonic stem cells

Answer 16

• from inner cell mass
• capable of giving rise to all of the cell types in the body (incl. non-regenerative)
• can be divided many times in culture to make many cells

Question 17

umbilical cord and placenta stem cells

Answer 17

• isolated immediately after birth
• more flexible (pluripotent)
• limited research tho
• easily isolated and banked

Question 18

stem cell activation in the liver

Answer 18

up to 90% of the liver is restored

1. priming: Kupffer cells release cytokines (IL-6) which acto on hepatocytes so parenchymal cells will receive and respond to growth factor signals
2. growth factor: HGF and TGF-α act on hepatocytes, which take several hours to progress from G₀ to G₁ to S phases in the cell cycle
3. after hepatocyte replication, nonparenchymal cell replication: Kupffer cells, endothelial cells and stromal cells
4. termination: hepatocytes return to quiescence

Question 19

Pros and cons of cell souce for stem cell therapies

Answer 19

• ES: grows well and is pluripotent; non-self and directed differentation
• iPSC-self: grow well, pluripotent and self; directed differentiation, labour intensice and inefficient
• neonatal: good availability, can be self; poor growth, numbers and cell type
• adult: limited plasticity, can be self; poor growth, poor numbers/accessibility