Intro to Stem Cells and Regeneration

Question 1

What are the criteria for being a stem cell?

Answer 1

Stem cells can self-renew and differentiate

Question 2

Define self-renewing

Answer 2

When stem cell divides and the cell retains all of its existing properties = remaining in undifferentiated state

Question 3

Define differentiation

Answer 3

When a stem cell receive a signal from the environment it responds by expressing a certain set of genes

This happens in a stable manner, so that when the env signal is removed the genes stay being expressed

Question 4

What type of division do stem cells go through?

Answer 4

Asymmetrical division 80% of the time

20% can be other things such as symmetrical division

Question 5

How can we tell if a cell is a stem cell?

Answer 5

Most of the time it is impossible

But we can go based of the criteria

Question 6

Define potency

Answer 6

The ability of ANY cell to differentiate

Question 7

Define totipotent

Answer 7

A cell that can give rise to EVERY cell

Question 8

Define pluripotent

Answer 8

A cell that can give rise to make all SOMATIC cells

Question 9

What can pluripotent cells not give rise to?

Answer 9

Extraembryonic tissue or an ENTIRE organism

(The cell may be able to make every cell in that organism though)

Question 10

When does potency become restricted?

Answer 10

With developmental age and tissue restriction

Question 11

What is an embryonic stem cell?

Answer 11

Derived from the inner cell mass of blastocysts

AND

Maintained indefinitely in vitro

Question 12

What are the 3 characteristics of embyonic stem cells?***

Answer 12

Pluripotent = can make all germ layers

Fast cycling (peculia cell cycle)

Symmetrically expanding

Question 13

What are somatic stem cells?

Answer 13

Also known as adult stem cells, are found in many tissues throughout the body

(while embryonic stem cells are found in embryos)

Question 14

What are the characteristics of somatic stem cells?

Answer 14

Rare (uncommon)

Slow cell cycle

Both (a)symmatric cell division

Unspecialised

Question 15

Why are somatic stem cells unspecialised?

Answer 15

They do not do most of hte work in that tissue because are not specialised to fulfil that specific function

Question 16

What is regeneration?

Answer 16

Homeostasis & repair

Tissues with natural turnover (blood, skin, etc..)

Question 17

Does regenration need stem cells?

Answer 17

No

Question 18

How does regeneration occur in the mucsle?

Answer 18

Satellite cells merge with myofibres after damage and can help it repair

So stem cells are known as “reserve cells” for injury repair

Question 19

Why do different organism have different regerneation potential?

Answer 19

Because they have different genetics

Question 20

What is lineage restriction? ***

Answer 20

The biological phenomenon whereby developing cells progressively lose fate potency for all but their adopted lineages, is foundational to multicellular lifeforms as it secures the functional identities of the myriad cell types in the body

Question 21

What experiment looked into axolotl regeneration?

Answer 21

Created a fluorescent axolotl

Transplanted different tissues into non-fluorescent axolotl

Damaged the recipient to see how transplanted cells respond

Question 22

What ages were the flurescent axolotl cells transplanted?

Answer 22

Either embryo stage or adult

Question 23

Conclusion of axolotl regernation?

Answer 23

The transplanted cells stayed as their own cell type

Example: if they transplanted skin them amputated, the cells only contributed to the skin not all tissues

Question 24

What are the two theories of the lineage of stem cells?***

Question 25

What is stemness?

Answer 25

Concept that stem cells share common characteristics

Meaning they may share transcriptional profiles

Question 26

What technique was used to look for stemness?

Answer 26

Microarrays to compare ESC, HSC and NPC with differentiated cells of the same lineage

Question 27

What genes did they find in common between the different stem cells?

Answer 27

The genes that allows stem cells to be metabolically active