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ICB - Stem cells > Stem Cells 1 > Flashcards

Stem Cells 1 Flashcards

1
Q

What determines the cell type?

A

Gene regulation, determined by receptors, transcription factors and epigenetics

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2
Q

What is differentiation?

A

A cell becoming specialised

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3
Q

Why is it important to ensure a stem cell can’t start cycling when you engineer them to put them back in a patient?

A

To ensure they can’t start cycling again and cause a tumour.

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4
Q

What is the name of the cell cycle state of a stem cell in an adult body?

A

G0

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5
Q

Who first showed that a differentiated cell could be pushed back into ‘undifferentiated’ state?

A

John Gurdon, 1962

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6
Q

What experiment did John Gurdon perform?

A
  • took nucleus of frog egg (oocyte)
  • replaced with nucleus of tadpole
  • a complete frog was able to develop
    So clearly the oocyte contains things that an bring donor nucleus bac to undifferentiated state –> ‘reprogrammed’
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7
Q

What are the key characteristics of stem cells?

A
  • Self renewal
  • Divide by mitosis to produce two daughter cells
  • At least on daughter can differnetiate
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8
Q

What is the potency of a stem cell?

A

The number of cell a stem cell can differentiate into

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9
Q

How potent are totipotent cells?

A

These can differentiate into any cell in the organism including extraembryonic tissue for four days after fertilisation

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10
Q

How potent are Induced pluripotent stem cells/Embryonic stem cells?

A

Can differentiate into all cell of the organism but not the placenta

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11
Q

What is a blastocyte?

A

A preimplantation embryo.

Implantation occurs 4-5 days after fertilisation

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12
Q

What is the structure of a blastocyte?

A

Hollow except for a small mass of pluripotent cells attached to one wall of the blastocyte known as the inner cell mass (ICM)

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13
Q

What is the ICM made up of?

A

Embryonic stem cells

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14
Q

Can embryonic stem cells differentiate into all 3 germ layers?

A

Yes

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15
Q

What are the 3 main germ layers?

A

Ectoderm
Mesoderm
Endoderm

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16
Q

Name examples of what the ectoderm might differentiate into.

A

Brain neurone, Pigment cells, Skin cells of epidermis

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17
Q

Name examples of what the mesoderm might differentiate into.

A

Cardiac, Skeletal and smooth muscle, red blood cells, tubule cell of kidney

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18
Q

Name examples of what the endoderm might differentiate into.

A

Alveolar cell, Thyroid cell, Pancreatic cell

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19
Q

The ectoderm is the

a) middle layer
b) external layer
c) internal layer

A

b) external layer

mesoderm is the middle layer and the endoderm id the internal layer

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20
Q

What is a germ layer?

A

A primary layer of cells that form during embryogenesis

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21
Q

Give an example of how pluripotent cells act as useful tools?

A
  • to understand developmental biology
  • to investigate the molecular and cell biology of disease
  • to test drugs and other therapeutics on
22
Q

Give an example of how pluripotent cells act as useful therapies?

A
  • to repair damaged/diseased tissues
  • to replace diseased/dying cells
  • to support diseased cells
23
Q

To maintain pluripotency you need to activate genes that maintain pluripotency. Name an example of these?

A

Wnt

Tgfbeta

24
Q

To maintain pluripotency you need to repress genes that differentiate pluripotency. Name an example of these?

A

Pax6

25
Q

What is the known function of Oct4, Nanog and Sox2?

A

They are transcription factors that are expressed in Embryonic stem cells and are involved in maintaining pluripotency.

26
Q

Why are some people ethically opposed to human embryo research?

A
  • embryo destroyed
    in the UK embryos can be researched on for 14 days after fertilisation.
    Hence there has been a drive to produce non embryonic pluripotent cells.
27
Q

How did Takahashi and Yamanaka discover it was possible to produce IPSC?

A

They introduced Oct3/4, Sox2, c-Myc and Klf4 (small group of transcription factors) into a mouse embryonic adult fibroblast (ie differentiated cells!) and resulted in cells that behaved like ES cells.

28
Q

Is it possible to produce iPSCs from patients to development replacement organs without risk of rejection?

A

It is possible in theory, however it is not yet possible

29
Q

What is the teratoma test?

A

Take a mouse with no immune system, inject iPSCs and see what tumours develop.
they can develop teratomas, which are tumours whuch are disordered embryos and contain derivations of all 3 germ layers.

30
Q

What is a nude mouse?

A

A mouse with no immune system

31
Q

What further tests exist to test iPSCs?

A
  • remove pluripotency maintaining TFs and observe differentiation
  • Growing hanging drop embroids
  • grow complete embryo
32
Q

What was the old method of delivering TF to cell to create iPSCs and why is it no longer used widely?

A

Viral delivery.
This was considered too risky.
For example C-MYC is a very powerful oncogene so you don’t really want to engineer it in a virus

33
Q

Name some example modern techniques of delivery of TFs used to create iPSCs.

A
  • Using microRNA
  • Using plasmids
  • Using recombinant protein
  • Using small molecules
34
Q

What are some disadvantages of the modern techniques to deliver TFs to a cell?

A

Take a very long time to work… many days

35
Q

Are Unmethylated genes with euchromatic histones poised to be expressed?

A

Yes

36
Q

Are methylated genes with heterochromatic histones poised to be expressed?

A

No, they are poised to be silenced

37
Q

iPSCs sometimes have cel memory. ie. cells that used to be a blood cell is more likely to again become a blood cell. Why is this?

A

Some form of epigenetic difference is maintained.

38
Q

What are the key signals in midbrain development?

A

Wnt
FGF8
Shh

39
Q

Can you make dopamine neurones in a dish?

A

Yes
You can use this to study why misfolded proteins kill them. This can be used to study Parkinson. The theory is that you can inject these into brains to replace neurones

40
Q

In the early embryo where is the only part of the brain to make dopamines?

A

The bottom of the mid brain.

41
Q

Where does the bottom of the mid brain get its signal to make dopamine neurones from?

A

The isthmus

42
Q

What is transdifferentiation?

A

To push from one lineage to another without going though pluripotency.

43
Q

What was Nanog used as by Demos et al?

A

It is produced by cells and used as a maker for pluripotency.

44
Q

What did Demos et al managed to achieve?

A

Turned neurons from brain with motor neurone disease into iPSCs, which maintained the disease causing mutation allowing them to develop cultures of patient specific disease causing mutations in vitro. Powerful tool in researching the disease. CRSIPR to clip out mutations being considered etc.
Then formed embryoids bodies and treated them with signals to achieve neurones that they could study.

45
Q

What did Yang Et al achieve?

A

To the Demos et al paper further and investigated with drugs to suggest why previous drugs had failed

46
Q

What is Rett syndrome?

A

Progressive neurological disorder in females (X-linked gene encoding methyl-CpG binding protein MeCP2)
Normal development until 18month old, then motor decline, regression, weak muscles, seizures, autistic behaviour.

47
Q

What was found out about neurones of rett suffers?

A

Synapses were less able to form and they had different electrophysiology.

48
Q

Give an example of a future application of iPSCs.

A

Patient specific iPSCs used for testing drugs for effectiveness before administering to patient.

49
Q

Why might iPSCs be relevant to parkinsons?

A

Why do dopamingeric neurones die? We don’t know.

iPSCs could be used to ceate dopaminergic neurone and look at them in vitro

50
Q

Why might iPSCs be relevant to Alzheimer’s?

A

•Modelling Alzheimer’s Disease with iPSCs reveals stress phenotypes associated with Intracellular Aβ and Differential Drug Responsiveness.

ICB - Stem cells (2 decks)

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