Wk 16: Gene therapeutics for managing difficult to treat diseases Flashcards
What are treatable acquired diseases?
More than 1 affected + no clear indication of defect (cancer, parkinson + alzheimers)
What are the advantages + disadvantages of using viral vectors?
+ Various types of viruses employed
+ Transfection efficiency
-Safety risks
- High immunogenicity after repeated admin
- Oncogenicity due to mutagenesis
- DNA = small size
What are the advantages + disadvantages of using non-viral vectors?
+ Coupling on polymers
+ Large DNA can be carried
+ Prod large quantities + cheap
+ Lower safety risk
- Low transfection efficiency
What is the main property of DNA?
Highly charged polyelectrolyte:
-Due to extra + intracellular electrolyte conc stretched out
- Due to -ve charge repulsive electrostatic interaction btw DNA + -vely charged cell surface
What are the properties of the carrier systems used?
- Strong enough to protect DNA from DNases
- Weak enough to release DNA inside target cell
What are examples of carrier systems?
- Lipoplexes
- Polyplexes
- Nanoplexes
What are the problems associated with in vivo gene delivery by cationic liposome DNA complex?
- Complex encounter negatively charged entities: flocculation + embolism + +vely charged particles cleared via reticuloendothelial system
- Pulmonary delivery: lung surfactant
- Loss of +ve charge = deterioration of transfection performance
What is the gold standard of non viral vectors?
Polymer polyethylene imine:
- Complexes large molecules
- Homogeneous spherical particles
- Protection against nuclease degradation
- Toxic
What was VEGF gene therapy used for?
Increase angiogenesis in dec blood flow caused by ischaemic heart disease
What is the most recent gene therapy?
Spinraza - spinal muscular atrophy
What is chitosan?
- Biodegradable, linear aa polysaccharide
- Derived from biopolymer chitin
- Used in food prep
- Polyplexes = stable, small + toroidal
In order to be stable + transect the target cells. What must the percentage of positively charged monomer units in chitosan polyplexes be?
> 65%
