Gene Therapy (Ch. 26) Flashcards
What are the 3 purposes for gene therapy?
- exchange abnormal gene for a normal one
- repair an abnormal gene
- alter regulation of a gene
What are the 3 essential elements of gene transfer?
vector, gene to be delivered, target cell
What are the 2 modes of gene therapy?
in-vivo = create gene → transgene packing into virus→ injection into person
ex-vivo = remove stem cells from patient→ viral transduction in lab w/ modified gene in stem cells→ inject cells back into person
Why are viruses commonly used as vectors in gene therapy?
can encapsulate and deliver their genes to human cells pathogenically
Manipulate the virus genome»_space; removing disease-causing genes»_space; insert therapeutic genes
What are the 7 pitfalls of gene therapy?
- Transient/low-level expression
- toxicity
- Immune and inflammatory response
- Difficulty reaching target issue
- Need for precise regulation of gene activity
-Viral reactivation in host - chance vector might stimulate immune system in a way that reduces the gene therapy’s effectiveness
What are the 7 vectors used in gene therapy?
- retroviral
- lentiviral
- adenoviral
- adeno-associated virus
- herpes simplex-virus-1
- liposomes
- naked DNA
What are retroviral vectors?
reverse transcriptase = therapeutic RNA –> DNA –> integrates into host chromosome
What are the advantages and disadvantages of retroviral vectors?
A: integrates therapeutic gene into host genome
D:
- risk of insertional mutagenesis
- Activate proto-oncogene
- ineffective in nondividing cells
What are lentiviral vectors?
can enter nondividing cells through pores in the nuclear membrane (ex. HIV)
What are the advantages and disadvantages of lentiviral vectors?
A: Persistent gene transfer in transduced tissues
D: Might induce oncogenesis
What are adenoviral vectors?
dsDNA viruses, can infect BOTH non-dividing and dividing cells; does not integrate into host genome
What are the advantages and disadvantages of adenoviral vectors?
A: Highly effective in transducing various tissues
-Infect dividing and nondividing cells
D: Viral capsid triggers strong immune responses
- short lifespan
What are associated adenoviral vectors?
ssDNA = can insert genome at a specific site on chromosome 19
What are the advantages and disadvantages of associated adenoviral vectors?
A: activate few inflammatory responses; can enter nondividing cells
D: Limited packaging capacity
What are Herpes simplex virus 1 vectors?
dsDNA that infects neuronal cells
What are the advantages and disadvantages of Herpes simplex virus 1 vectors?
A: large packaging capacity with persistent gene transfer
D: residual cytotoxicity with neuron specificity
What are liposomal vectors?
artificial lipid sphere with an aqueous core
What are the advantages and disadvantages of liposomal vectors?
A: can cross cell membranes
- Transfers many cell types
- large holding capacity
- not stimulate immune response bc no peptides
D: costly$$$
What are naked DNA vectors?
DNA with no proteins, molecules or lipids
What are the advantages and disadvantages of naked DNA vectors?
A: Efficient in gene transfer - limited immunogenicity
D: Transient and low-level expression
What are ribozymes?
RNA molecules with enzyme activity that can cleave mRNA
Which vector is most-commonly used? Why?
associated adenoviral vectors
- can insert genetic material into host genome
- only mild inflammatory response
- can enter non-dividing cells
What are 6 different types of gene therapy?
- Plasmid DNA
- Viral vectors
- Bacterial vectors
- Human gene editing technology (CRISPR)
- Patient-derived cellular gene therapy products
- Liposome
What is CAR-T?
successful cancer therapy
T cells will identify cancer cells = genetically modified to fight off cancer cells
What are cationic polymers?
larger macromolecule that is charged to get inside the cell
What disease has gene transfer been more used in?
cancer
