In Vitro Models of Disease

Question 1

What are the models for disease?

Answer 1

A model demonstrates a particular COMPONENT of a disease

Cellular models (in vivo, ex vivo)
animal models (in vivo)
Human tissue / cells (in vitro)

Question 2

Why does someone want to use disease models?

Answer 2

• Understand disease pathogenesis (mostly end stage pathogenesis, early stage would be better)
• Identification of new drug targets
• Test new drugs (efficacy and toxicity)

Question 3

Whats the pathway of drug development?

Answer 3

• Discovery/ Drug development
• Preclinical testing including:
  
  • In vitro, ex vitro (cell models)
  • in vivo (animal models)
  • in silico (computer based models
• Regulatory approval
• clinical trials
• Human treatment

Question 4

What does an in vitro model need to do?

Answer 4

• Be a representative model of disease
• Identification and validation of new targets
• Effectiveness of new therapies
• prerequisite to clinical trials
• Find a gold standard disease model

Question 5

What can be used for in-vitro models?

Answer 5

• Immortalised cell lines (most common)
• Primary human cells
• Human embryonic stem cells
• Cell reprogramming (induced pluripotent stem cels (iPS)
• Human organoids ( ex-vivo)

Question 6

What are immortalized cell lines?

Answer 6

Definition: A population of cells from a tissue source that would not normally proliferate indefinitely but due to a mutation (natural or intentional) they keep undergoing division

Question 7

Whats some examples of immortalized cell lines?

Answer 7

Hela cell line (cancer)
PC12 cell line (embryonic neural crest)
SH-5Y5Y (neuroblastoma)

Question 8

Whats the advantages of immortalized cell lines?

Answer 8

Continuous supply of cells
limited variability
Easy to culture and manipulate

Question 9

What are the disadvantages of immortalized cell lines?

Answer 9

• Do not act like real human cells
• No human variability (epigenetics)
• Not a real disease model
  (PC12 = rat cells for modelling parkinsons)
  ( SH-5Y5Y cell modelling parkinsons = neuroblastoma/ cancer)

Question 10

What are primary cells?

Answer 10

Isolated cells from human tissues i.e heart, lung, blood but not all tissues i.e brain cells

Question 11

Whats a hindrance of primary cells?

Answer 11

Limited life span

Question 12

Whats a good about primary cells?

Answer 12

• Primary cells more closely mimic the physiological state of cells in-vivo and generate more relevant data representing living systems i.e
• human cells
• may be disease i.e cancerous cells
• Isolated from human tissue

Question 13

Whats bad about primary cells?

Answer 13

• Hard to culture

- Limited life span

Question 14

What are human embryonic stem cells?

Answer 14

They are:
Pluripotent
- Continue to undergo either sym or Asym division
- Able to generate other tissue in the body
- Obtained from a blastocyst

Question 15

Can HES cells model disease?

Answer 15

• They may come with disease

- Can introduce the disease through mutation (genetic manipulation)

Question 16

What is cell reprogramming?

Answer 16

Induced pulripotent stem cells

Question 17

How does IPS work?

Answer 17

Able to use skin from patients to generate a model with parkinsons disease through genetic manipulation?

Question 18

Why use skin in IPS?

Answer 18

Skin contains fibroblasts which express genes for

• Oct 3/4
• COX 2
• KLF 4

Question 19

What does pluripotent mean?

Answer 19

• Continue to undergo division

- Able to generate all tissues in the body

Question 20

Whats some advantages of IPS?

Answer 20

• More ethical that HES

- Know patients clinical details and can model the patients disease

Question 21

What are the uses of IPS?

Answer 21

Model human disease
- Live human tissues
- Variability, epigenetics
Investigate pathogenesis
Identify new drug targets
test new drugs (efficacy, toxicity)
Tests can be done at any stage of disease developemtn (great!)

Question 22

Whats the chance a developing drug will fail during clinical trials?

Answer 22

80% of drug fail during clinical trials

This is because each patient has variability (unique factors) Therefore models need to have variability and human qualities

Question 23

Whats the disadvantages of IPS?

Answer 23

• Long time to generate mature cells (~3 months)
• Low Yeild
• Variability leads to large errors in data and can lead to no statistical evidence, however if the drugs work then it works for a lot of people.

Question 24

What are human organoids?

Answer 24

3D organs generated from human pluripotent stem cells.

3D structure

• cells align correctly as would in vivo
• alllows proper cell connection

organs generated

• liver
• pancreas
• gut
• brain

Question 25

Whats the gold standard of disease models?

Answer 25

IPS

= Drug and target indentification
= genetic testing
= variability = success