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02. MCM Test 2 > 9. Stem Cells > Flashcards

9. Stem Cells Flashcards

1
Q

Define a “stem cell niche”

A

Stem cells being regulated by the cells around them.

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2
Q

Why can stem cells divide “functionally without limit?”

A

Because they express telomerase, which keeps their telomeres from getting too short.

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3
Q

Why is it important that stem cells divide slowly?

A

Because unchecked, undifferentiated cell replication could be devastating if it attained cancerous quality.

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4
Q

What are the characteristics of a Totipotent Stem Cell?

A

Has the ability to give rise to all the cells in an organism, including extraembryonic tissues

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5
Q

What are the characteristics of a Pluripotent Stem Cell?

A

Has the ability to give rise to all cells of that given embryo, and all adult cells after it. (Cannot grow extraembryonic tissues)

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6
Q

What are the characteristics of a Multipotent stem cell?

A

They can give rise to any cell of a given lineage.

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7
Q

Where might one gather pluripotent stem cells?

A

In the inner cell mass of a blastocyst.

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8
Q

How do founder cells determine the size of large organs?

A

They emit short range signals that encourage growth up to a set number of cell diameters.

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9
Q

What are transit amplifying cells?

A

They are not stem cells, as they are committed.

They are pre-programmed to have a finite number of divisions.

They create a set number of terminally differentiated cells as a method of growth control.

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10
Q

What is different about stem cell division from normal cell division?

A

They use divisional asymmetry - one cell differentiates, and one cell remains a stem cell.

The DNA strand that was originally in the mother stem cell - with all of its methylation patterns, unique transcription factors etc - remains in the mother cell (immortal strand hypothesis)

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11
Q

What is environmental asymmetry?

A

When a cell divides into two identical progeny, but the environment changes one into something else.

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12
Q

What would happen if you put a mouse embryonic stem cell into a blastocyst of a different mouse?

A

It would integrate into the blastocyst, and you would have a chimeric mouse

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13
Q

What type of stem cell can give rise to a teratoma?

A

An embryonic stem cell

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14
Q

What prevents us from using embryonic stem cells as a direct therapeutic agent?

A

Their ability to form teratomas, rather than fixing the tissue around them.

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15
Q

How do you grow Embryonic Stem Cells (ES cells?)

Why must you use serum free medium?

A
  • Isolate them from an embryo
  • Place them on a plate of irradiated “feeder cells” (often mouse fibroblasts that express growth factors)

Serum contains growth factors that can cause stem cell differentiation

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16
Q

(Surprise card from the DSA so I don’t forget)

What is the equation to calculate a patient’s estimated osmolality?

A

Estimated osmolality = 2 x Na + Glucose / 18 + BUN / 2.8

17
Q

What are Nanog, Oct4, Sox2, and FoxD3?

What are Cripto and GDF-3?

A

They are transcription factors that maintain pluripotent stem cells.

Growth factors found in pluripotent stem cells

18
Q

What do hematopoietic stem cells give rise to?

What about mesenchymal stem cells?

A

Blood components (platelets, RBC, WBC)

Tissues (bone, cartilage, fat, etc)

19
Q

What is special about cord blood?

A

It can be used to treat a variety of disorders without genetic manipulation.

20
Q

What sort of regenerative therapies use adult stem cells?

A

Neuro-regeneration

Bone marrow transplants

21
Q

What are the challenges for regenerative medicine?

A

Immune rejection

Lack of knowledge

Ethics

22
Q

What is somatic cell nuclear transfer?

What are the benefits?

A

A combination of cloning and embryonic stem cell technology.

Overcomes the issue of rejection by using the patient’s own genes.

Enables the reprogramming of adult cells, removing the ethical issue.

23
Q

How might one induce pluripotency in an adult fibroblast cell?

A

Reprogram them (using viruses) and treat with embryonic stem cell transcription factors (KLF4, SOX2, c-Myc, Nanog, Oct 3/4, LIN-28)

24
Q

What is the risk with induced pluripotent stem cell therapy?

A

Much higher risk for teratoma formation than with natural ES cells.

25
Q

How are cells prepared in somatic cell nuclear transfer?

What are you left with?

A

Take an egg cell, take the nucleus out, fuse a (nucleated) somatic cell with the egg, and stimulate division.

You are left with a blastocyst, from which you can remove the inner cell mass as you would normally.

26
Q

What are the challenges of SCNT?

A

Very technically demanding

Hard to source human egg cells

02. MCM Test 2 (14 decks)

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