Stem Cell Applications

Question 1

What is a stem cell?

Answer 1

A primitive cell that can clone itself or create daughter cells that are more specialized

Question 2

Stem cell characteristics

Answer 2

1) Not terminally differentiated
2) No limit to division
3) Division leads to 1 stem cell daughter and another daughter that can be differentiated

Question 3

Main characteristic of Adult stem cells

Answer 3

-They are tissue specific (epidermal stem cells = epidermal cell types)

Question 4

What are the three levels of potency?

Answer 4

1) Totipotency - can make all cells (zygote)
2) Pluripotency - give rise to all embryo cells and subsequent adult tissue cells (blastocyst)
3) Multipotency - give rise to cell type of a certain lineage; partially committed (adult stem cells) (Various tissues)

Question 5

How many cells is a zygote totipotent for?

Answer 5

16

Question 6

What does cell differentiation depend on?

Answer 6

What you feed into the culture

Question 7

What are founder stem cells?

Answer 7

• Stem cells that have fixed number of division (think finger: you only have 5)
• Each tissue has fixed number of FC populations
• Controlled by short-range signals

Question 8

What are Transit Amplifying Cells?

Answer 8

-Committed cells
Key: they divide a finite number of times before becoming differentiated
-THEY DIVIDE FREQUENTLY
-move from stem cell -> committed tissue cell

Question 9

What is the key to stem cell maintenance and how is it accomplished?

Answer 9

-50% of daughter cells must remain as stem cells and retain original DNA

1) Divisional asymmetry - one specialized daughter, one stem cell characteristic daughter
2) Environmental asymmetry - two identical cells made but environment alters

Question 10

What is the Immortal Strand Hypothesis?

Answer 10

• Some tissues’ stem cells retain original DNA to PREVENT GENETIC ERRORS
• Divisional asymmetry preserves

Question 11

What are the types of stem cells?

Answer 11

1) embryonic
2) adult/tissue specific
3) fetal
4) cord blood
5) Induced pluripotent
6) somatic cell nuclear transfer

Question 12

Stem Cell Hierarchy

Answer 12

-Two types: Embryonic and Adult

SC differentiate into specialized cells in stages -> stages need multiple factors (epigenetic) to restrict DNA expression in order to produce proper cell -> DNA expression can pass onto daughter cell or daughter remains stem cell

Question 13

Embryonic Stem Cells

Answer 13

• From blastocyst
• Proliferate indefinitely, unrestricted potential (totipotent and pluripotent)
• CAN BECOME A TUMOR if injected late into embryo development
• Various tissues form when injected into host animals

Question 14

What are Tertomas?

Answer 14

• A tumor with a variety of different tissues

- Made from Embryonic stem cells —> can’t generate a full body plan on their own like a full embryo

Question 15

What are the transcription factors in pluripotent cells and why are they important?

Answer 15

TFs:

1) Nanog
2) Oct4
3) Sox2
4) FoxD3

-Necessary for establishment and maintenance of pluripotent sc

Question 16

Adult Stem Cells

Answer 16

• Fixed in tissues with degree of plasticity
• respond to growth and repair demands
• Restricted capacity and growth potential

Question 17

Hematopoietic & Stroma/Mesenchymal Stem Cells

Answer 17

• From bone marrow
• HSC = blood related
• MSC = fat, heart, muscle, etc.

Question 18

Cord Blood Stem Cells

Answer 18

• Undifferentiated, adult stem cells

- Can treat over 70 disease

Question 19

What are the central strategies of Regenerative Medicine?

Answer 19

1) Pluripotent cells
2) Differentiated in vitro
3) Reprogram primary cells

Question 20

Challenges for Regenerative Medicine?

Answer 20

1) Producing right amount of proper cells
2) Proper integration into tissues
3) Embryonic/fetal grafts might be immunogenic

Question 21

What are two adult stem cell therapies?

Answer 21

Neuro-regeneration is big

1) Bone marrow derived mesenchymal stem cells
2) Adipose derived mesenchymal stem cells

i.e. bone and fat

Question 22

What does somatic cell nuclear transfer (SCNT) allow us to do?

Answer 22

• Bypass host rejection by taking nucleus from a somatic cell and inject it into donor oocyte in place of oocyte nucleus
• Allows or removing controversial embryo step

Question 23

What gene regulatory proteins determine embryonic stem cell character?

Answer 23

Oct3/4, Sox2, Myc and KIf4

-Useful to know if you want to maybe turn adult stem cells into embryonic stem cells

Question 24

What are Induced Pluripotent Stem Cells?

Answer 24

• Undifferentiated Adult stem cells (from patient) that are turned into pluripotent stem cells via DNA recombination
• Can’t become any specialized cell but a good amount
• High potential for teratomas

Question 25

What are the steps for Somatic Cell Nuclear Transfer?

Answer 25

1) Fuse egg (no nucleus) with a somatic cell (with nucleus)
2) Stimulate cell division
3) Allow blastocyst to form
4) Extract inner cell mass from the blastocyst (not implanting blastocyst at this stage restricts cloning – think DOLLY!)
5) Culture the new pluripotent embryonic cells

DOLLY made this way!!

Question 26

Challenges of SCNT in Disease Treatment

Answer 26

1) Inefficient - may need hundreds of oocytes
2) Demanding — skilled staff needed

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