Human gene therapy: · The use of recombinant genetic material (DNA, RNA or hybrid molecules) under diff forms of pharmaceutical preparations as a therapeutic agent. · Somatic gene therapy: treat tissue that is defective in the patients · Germ line gene transfer: manipulate sperm/egg to prevent birth of child w a genetic defect. Banned. · CRISPR/cas9 system. · Most trials are taking place in the USA, but also Europe. Gene therapy delivery protocols: · In vivo: (normally a viral vector) - inject into part of the body where it is needed e.g. muscles, liver, brain. Delivery to CNS - inject. - Parkinson's disease: Adeno-associated viral vector expressing the glutamic acid decarboxylase (GAD) gene directly into neurons. · Ex vivo: cannot deliver therapy to target cell population e.g. haematopoietic stem cells (one marrow). Cannot target delivery as virus infects the first cell which it encounters, and the bone marrow stem cells constitutes 1/5000 cells in the bone marrow. Sufficient numbers to affect therapy is negligible. This method removes cells that we want to infect from the patients, grow them in tissue culture, genetically augment them, using a viral vector we infect the cells and grow them more and return them to the patient where they will go back to where they came from. - Requires more sophisticated kit under sterile conditions. · Gene therapy protocols have been developed to target 'acquired' genetic diseases as well as inherited diseases. Gene Therapy Inherited Disorders Homologous Tissue B-thal/RBC DMD/muscle CF/lung Acquired Disorders Cancer Cardiovascular AIDS Ectopic Systemic Secretion Oncolytis viruses Suicide Genes/ Neo-vascularisation pro-drug Activation VEGF Anti-angiogenesis "Protein Factory" Tissue Repair FIX/FVIII Glucocerebrosidase GH Growth Inhibition Vaccines Cytokines Alloantigens Decoys Ribozymes Antisense RNAi/miRNA - B-thal/SCD: need to target bone marrow stem cells. - Metabolic disorders: provide missing product in the circulation. Don't need to deliver to liver (suite of production). Can make another part of the body in a protein factory to secrete that factor e.g. skin. Ectopic systemic secretion. - Acquired disorders: two drugs using gene therapy have been approved in the US for treating B-cell lymphoma.
Disease targets: Inherited single gene disorders: · Haemoglobinopathies: thal, SCD . CF · Muscular dystrophy · Ocular disorders Acquired disorders: · Cancer Cardiovascular disease . Diabetes · HIV Components of a gene therapy protocol: Components of a Gene Therapy Protocol Target Tissue Efficient Gene Delivery Transcriptional Control · Accessible ·Manipulable ·Viral vectors .Non-viral vectors ·Sufficiently high ·Sustained 1. Need to decide what it the target tissue/cell population, this is determined by the biology of the disease. Target tissue needs to be accessible or manipulable. 2. How to delivery gene therapy medicine: viral vectors or non-viral vectors - chemical based formula. 3. Design therapeutic transcription unit so that it expresses effectively after you've delivered it. . These components are interdependent: requirements within one area puts restraints on the others. · Therapeutic requirements for a given disease will dictate technical details. · No one procedure will fulfil the needs of all diseases. · Problems: access, non-dividing, ex vivo