Lecture 7: Gene Therapy Flashcards
Define gene therapy
The introduction, using a vector, of nucleic acids into cells with the intention of altering gene expression to prevent, halt or reverse a pathological process
What type of disorders are cystic fibrosis and haemophilia?
Single gene
Recessive loss of function
What type of disorder is Huntingtons Disease?
Single gene
Dominant negative
What type therapy can be used for cystic fibrosis and haemophilia?
Gene addition/ replacement
What type of gene therapy can be used for Huntington disease?
Allele silencing/ replacement
What disease uses gene therapy most commonly?
Cancer
What is the in vivo approach to gene therapy?
Single step process
Vector administered directly to patient
Targeted to specific organ/tissue (route of administration or specificity of vector)
What is the ex vivo approach to gene therapy?
Two step process Cells removed from patient Vector added to cells in vitro Engineered cells returned to patient May be combined with (stem) cell-based therapy
List the barriers to gene therapy
Circulating antibodies
Ensuring target tissue has receptor required
Ensure viral DNA is taken up in nucleus
Needs origin of replication
Issues when protein is produced if immune system hasn’t seen it before
What is the most used vector in gene therapy?
Adenovirus
What type of vectors for in vivo gene therapy are used?
Adenovirus
Adeno-associated virus
What type fo vector is mostly used in ex vivo gene therapy?
gamma-retrovirus
What are some issues encountered by in vivo gene therapy?
Difficulty of delivery to liver, retina and brain
Adenoviral vectors can have high incidence of neutralising antibodies
What are advantages of adenovirus vectors?
Large capacity: up to 30kb if helper virus supplied
Easily purified
Infect broad range of cell types
Efficient transduction
Potential vector for cancer treatment (expression of anti-cancer proteins)
Describe the features of adeno-associated virus
Small
Non-pathogenic
rep and cap genes can be replaced with expression cassette
Can be used in non-dividing cells
