Gene therapy Flashcards
What is gene therapy
Use of recombinant genetic material (DNA, RNA or hybrid molecules) under different forms or pharmaceutical preparations as a therapeutic agent
Gene therapy in vivo and ex vivo what does it involve
in vivo: injection
ex vivo: take blood, isolate haematopoietic target cells, gene transfer, reinfusion of gene modified cells /- BM conditioning
What is needed for efficient gene therapy
accessible and manipulable target tissue
viral+non viral vectors for efficient gene delivery
sufficiently high and sustained transcriptional control
What are target tissues for gene therapy
haaematopoietic system (stem cell, progenitor cellss, mature cells), muscle (myoblasts, myofibres), liver (hepatocytes), vasculature (endothelium, SM), skin, (keratinocytes, fibroblasts) CNS (neurons, glia, microglia), Lung (epithelium)
Problems in gene therapy and what are ideal cell targets
Problems: access, nondividing, ex vivo procedure only
ideal cell target: pluripotent, self regenerating stem cells from patients being treated
How do viral gene therapy vectors work
For nonintegrating,the virus will not integrate genetic material into target cell population which comes with therapeutic limitation
For integrating, the therapeutic gene becomes permanent feature of genetic make up of target cell population, If stem cell, can exert therapeutic effect long term
How do retroviral/lentiviral vector design work
based on HIV. Cut and remove all disease causing gene and replace with therapeuttic gene
If a virus needs its genes to replicate itself, how do you do that when you remove all of its genes
Viral gene required to make viral components are present on separate DNA molecules.Introduce/transfect viral gene to cell line all 4 separate DNA entities: 1 encodes for actual therapeutic genome, others carry genes which transcribe+translate all proteins which are needed to pack viral genome into therapeutic viral entity which can be harvested and deliver to target cell populatoin
Successful ex vivo and in vivo gene therapy trials
Ex vivo: SCID, X linked chronic granulomatous disease, Junctional epidermolysis bullosa, beta thalassaemia/sickle cell disease
In vivo: Haemophilia B, Parkinson’s disease,Leber’s congenital amaurosis
SCID ADA problem and what treatment involves
deficiency of ADA. Purine metabolic defect. accumulation of toxic metabolites
treatment: selective advantage to cells that produce sufficient vector-derived ADA
treatment: ex vivo, BMCD34+ isolated, non myeloblative conditioning
What problems are arising with gene therapy
immunity against certain viral vectors and therapeutic gene products, therapeutic gene silencing, insertional mutagenesis with integrating viral vectors
Haemophilia B what is it and what is its current treatment
X linked bleeding disorder, defect in coagulation factor IX gene, serine protease that is criticall for blood clotting
current treatment: frequent intravenous injections of FIX protein,expensive and associated with antibody formation
Gene therapy for haemophila B
Peripheral-vein infusion of scAAV2/8-LP1-hFIXco led to FIX transgene expression at levels sufficient to improve the bleeding phenotype with few side effects
Can gene therapy be used to treat both inherited monogenetic disorders and acquired diseases
yes
What must gene therapy take into account
target tissue and disease biology, efficcacy of gene delivery, appropriate control of therapeutic gene unit
