Disease modelling/ drug screening Flashcards
What can cause a healthy state to turn into a diseased state?
1) Infection agents
2) Genetics
3) Doctors
4) Physical damage (raditation, chemicals)
What would need to happen to reverse damage? (drugs)
- Target for the drug to act upon
- The drug has to be discovered
- Drug must be turned into a useable drug and tested on people
What is the process of drug discovery?
1) Target identificaiton
2) Lead selection
3) Lead optimization
4) Pre-clinical development
5) Clinical trail phase 1
6) Clinical trail phase 2 + 3
What does the drug discovery process depend upon?
- Having a target
- Knowing the mechanism (biological processes underlying pathologies)
How can PSCs be used in drug discovery?
- Try to model disease in a dish
- Discover targets
- Test drugs to see if alter the disease phenotype
Why use hPSC to model human disease instead of animal models? (mouse)
Many differences between mice and humans:
1) Developmental biology
- Gastrulation
- Organogenesis
2) Physiological differences
- Heart rate
- Heart size
3) Physical differences
4) Genetic differences
How are genetics different between mice and humans?
- Some mutations in mice are fatal but in humans only cause a disease
- 20% human genes have no orthalogs in mice
What are othlogs?
Genes descended from the same ancestral sequence separated by aspeciationeven
What are the issue of using human cell lines?
- Cells do not grow optimally in medium
- Cell types tend to transform into cancer like cells
- Must change cells, not natural (not in vivo)
- Cells change to enable them to grow in lab environment
What are the 3 advantages of hPSC over conventional cell lines?
1) Normal, primary cell line
2) Grow indefinitely
3) Differentiate into any cellular fate
What is a ‘cell line’?
A cell culture developed from a single cell and therefore consisting of cells with a uniform genetic make-up.
What are the strategies for generating disease models?
1) Gene editing (CRISPR/Cas9) to add mutations
2) Induced pluripotency
What are the 6 criteria for feasibility of modelling a diseasse in vitro and why?
1) Inheritance
- Inherited in one gene is easier
2) Penetrance
- High penetrance is easier
3) Age of onset
- Embryonic is easier
4) Mouse model
- Less likely to do work in diseases with a good mouse model
5) Phenotype
- Easier if the phenotype shows in a cell by cell basis (not pattern formation)
6) Tissue
- Easier if differentiation is easy (make cell type interested in)
What is penetrance?
The proportion of individuals with a specific genotype who express a particular phenotype
What are the 3 ways that phenotypes can be measured?
1) High-throughput screening
2) High-content screening
3) Physiological arrays
What are the advantages of HTS?
Simple
High throughput
What are the disadvantages of HTS?
Not a single-cell
Needs target or reporter
What are the advantages of HCS?
Single-cell
Mid throughput
What are the dia=sadvantages of HCS?
Difficult assay
What are the advantages of physiological arrays?
Physiological
What are the disadvantages of physiological arrays?
Low throughput
Difficult assay
Which diseases have been modelled and tested with drugs?
1) Cardiac diseases
2) Schizophrenia
3) Alzheimer’s
