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Case unit 5 > Models > Flashcards

Models Flashcards

1
Q

How are marmosets used as a disease model?

A
  • injected with MPTP chemical –> kills cells in substantia nigra –> Parkinson’s disease
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2
Q

What model was used to investigate CML?

A

Myeloid cells –> injected with BCR-Abl transgene

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3
Q

What are the limitations of using petri dish cells as disease models instead of humans? (2D VS 3D)

A
  • no cell to contacts
  • diff cell signalling/ interactions
  • petri dish = rigid matrix but body is flexible
  • petri dish cell environment = atmospheric 02 –> stressful
  • where as body cells normoxic conditions
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4
Q

Benefits/Limitations of using marmosets as disease models

A 
Benefits
- allows therapy testing 
- develop similar symptoms to humans
Limitations
- can't study how Parksinson's develops
- Lesion is not progressive
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5
Q

Benefits/limitations of myeloid cells as disease model

A 
Benefits
- cheap and quick to grow
- easy to manipulate
- allows drug testing
-understand pathophysiology
Limitations
- 2D model
- can't learn about CML onset 
- more opportunity for cells to develop mutations
- cell lines vary over time
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6
Q

What are the benefits of using Zebrafish as a disease model?

A
  • good vasculature –> can investigate variables involving bloodflow
  • transparent –> can track therapies/chemicals
  • genetically tractable –> can easily introduce mutations
  • cheap
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7
Q

What have Zebrafish been used as a model to investigate?

A

Wound healing/ tissue damage and how it may be correlated with tumor growth SEE NOTES

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8
Q

How can use as mice as T1DM disease models?

A

inject them with a chemical that causes B-cell destruction –> induce hyperglycaemia

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9
Q

Why might inbred mouse strains be used? Give an example

A
  • can mimic aspects of human disease

- NOD mouse (non obese diabetic mouse)

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10
Q

What is a limitation of using inbred mouse strains?

A
  • complex genetic background

- so may not reflect cause of human disease

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11
Q

How may mutant mice be used as a disease model?

A
  • use CRISPR to knockout specific genes
  • investigate genetic diseases such as cystic fibrosis –> introduce CTFR gene
  • investigate genetic variants that predispose to Alzheimer’s
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12
Q

Why may mice with an introduced mutant CTFR gene still not develop cystic fibrosis the same procedure in pigs works?

A
  • ATPase pump not upregulated in mice
  • no mucosal acidification
  • resident immune cells can still function
  • so no thick mucous/bacteria build up
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13
Q

What are the limitations of using mutant mice? (4)

A
  • specific strains are used
  • time of experimentation can have different effects
  • depending on gender of mice feeder/carer –> diff responses
  • mice have clean cages –> no influence of diff microbiomes like in humans
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14
Q

What is a benefit of using mutant mice? Use a specific example

A
  • SCID-NOD mice
  • have no immune system
  • so can introduce patient human tumour cells (no rejection)
  • allows investigation of diff therapies
  • personalised medicine
  • enhance understanding of tumour biology
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15
Q

What are the limitations to using SCID-NOD mice for PDT X? (4)

A
  • can’t predict affect of immune system on therapies
  • can’t investigate immunotherapies
  • expensive
  • time consuming
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16
Q

How could you repopulate the immune system of a SCID-NOD mouse?

A

Take a graft of human stem cells from bone marrow –> introduce into mice
*see other ways in notes

17
Q

Give and explain an example of a personalised model.

A

Avatars

  • patient tumour cells DNA sequenced
  • creates a mutation profile
  • create cancer specific mutation in mice/flies
  • test specific therapies
18
Q

What are organoids derived from?

A
  • primary tissue

- OR embryonic/ induced pluripotent stem cells

19
Q

Outline the steps in creating an organoid (4)

A
  1. harvest tissue sample
  2. take epithelial/ embryonic stem/ induced pluripotent stem cells
  3. give 3D collagen support
  4. treat with hormones/selection of factors that promote differentiation into cell type of interest
20
Q

List the uses of organoids (5)

A
  1. omics profiling
  2. study host-microbe interaction
  3. high throughput drug screening
  4. disease model
  5. gene editing –> targeted correction of mutations
21
Q

What are the benefits of using organoids as disease models?

A
  • can study in vivo biological processes e.g. tissue renewal/drug response
  • physiologically more similar to humans
22
Q

How does the sgRNA flag the 20 bp target sequence?

A
  • has RNA complementary to the target seq

- so will base pair with target seq and displace other strand

23
Q

How is the CRISPR machinery created and introduced into a target cell?

A
  • DNA coding for sgRNA and Cas9 binding seq introduced into plasmid downstream of a promoter
  • plasmid also has cDNA for Cas9 with promoter
  • introduced into target cell using transfection/viral transduction
24
Q

What are the 2 types of mammalian DNA repair?

A
  1. homologous end joining - v quick can cause INDELS

2. homologous recomb.

25
Q

How can homologous recombination be used in CRISPR to repair mutated gene?

A
  • target CRISPR to mutated gene
  • also introduce plasmid with wildtype gene
  • plasmid must have DNA seqs flanks that are homologous to regions surrounding the ds break
26
Q

How can you recruit other proteins to target seqs in CRISPR? What does it require?

A
  • using Cas9 fusions
  • mutant form of Cas9 with no nuclease activity fused with cDNA of protein
  • e.g. fluorescent probe

Case unit 5 (1 decks)

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