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- 1. A promising futureto disease treatment
- 2. Gene therapyis the introduction of genes into existing cells to prevent or cure a wide range of diseases. It is a technique for correcting defective genes responsible for disease development. The first approved gene therapy experiment occurred on September 14, 1990 in US, when Ashanti DeSilva was treated for ADA-SCID.
- 3. It isdefined as the replacement of a deficient gene product or repair of an abnormal gene with in an individual’s cells and tissues to treat disease.
- 4. SOMATIC CELL GENE THERAPY Therapeutic genes transferred into the somatic cells. Eg. Introduction of genes into bone marrow cells, blood cells, skin cells etc. Will not be inherited later generations. At present all researches directed to correct genetic defects in somatic cells. GERM LINE GENE THERAPY Therapeutic genes transferred into the germ cells. Eg. Genes introduced into eggs and sperms. It is heritable and passed on to later generations. For safety, ethical and technical reasons, it is not being attempted at present.
- 5. Ex vivo genetherapy:- transfer of genes to cultured cells and reinsertion. In vivo gene therapy:- direct delivery of genes into the cells of a particular tissue in the body
- 6. Transplant the modifiedcells to the patient. Select genetically corrected cells and grow. Introduce the therapeutic genes . Grow the cells in culture Isolate cells with genetic defect from a patient
- 7. 1st genetherapy – to correct deficiency of enzyme, Adenosine deaminase (ADA). Performed on a 4yr old girl Ashanthi DeSilva. Was suffering from SCID- Severe Combined Immunodeficiency. Caused due to defect in gene coding for ADA. Deoxy adenosine accumulate and destroys T lymphocytes. Disrupts immunity , suffer from infectious diseases and die at young age.
- 8. Direct deliveryof therapeutic gene into target cell into patients body. Carried out by viral or non viral vector systems. It can be the only possible option in patients where individual cells cannot be cultured in vitro in sufficient numbers (e.g. brain cells). In vivo gene transfer is necessary when cultured cells cannot be re-implanted in patients effectively.
- 9. In patientswith cystic fibrosis, a protein called cystic fibrosis transmembrane regulator (CFTR) is absent due to a gene defect. In the absence of CFTR chloride ions concentrate within the cells and it draws water from surrounding. This leads to the accumulation of sticky mucous in respiratory tract and lungs. Treated by in vivo replacement of defective gene by adenovirus vector . -Therapy for cystic fibrosis
- 11. To transferthe desired gene into a target cell, a carrier is required. Such vehicles of gene delivery are known as vectors. 2 main classes Viral vectors Non viral vectors
- 12. 1) RETROVIRUS VECTORSYSTEM The recombinant retroviruses have the ability to integrate into the host genome in a stable fashion. Can carry a DNA of size – less than 3.4kb Replication defective virus particles Target cell - dividing
- 13. 2) ADENO VIRUSVECTOR SYSTEM Adeno virus with a DNA genome – good vectors. Target- non dividing human cell. Eg. Common cold adenovirus.
- 14. 3) ADENO ASSOCIATEDVIRUS VECTOR It is a human virus that can integrate into chromosome 19. It is a single stranded, non pathogenic small DNA virus. AAV enters host cell, becomes double stranded and gets integrated into chromosome. 4) HERPEX SIMPLEX VIRUS VECTOR Viruses which have natural tendency to infect a particular type of cell. They infect and persist in nervous cells.
- 15. 1. PURE DNACONSTRUCT Direct introduction of pure DNA construct into target tissue . Efficiency of DNA uptake by cells and expression rather low. Consequently, large quantities of DNA have to be injected periodically. 2. LIPOPLEXES Lipid DNA complexes; DNA construct surrounded by artificial lipid layer. Most of it gets degraded by lysosomes.
- 16. 3) DNA MOLECULARCONJUGATES Commonly used synthetic conjugate is poly- L- lysine bound to specific target cell receptor. Therapeutic DNA is then made to combine with the conjugate to form a complex. It avoids lysosomal breakdown of DNA. 4) HUMAN ARTIFICIAL CHROMOSOME Can carry a large DNA ie, with one or more therapeutic genes with regulatory elements.
- 17. Gene Gun Employsa high-pressure delivery system to shoot tissue with gold or tungsten particles that are coated with DNA Microinjection Process of using a glass micropipette to insert microscopic substances into a single living cell. Normally performed under a specialized optical microscope setup called a micromanipulator. PHYSICAL METHODS
- 18. USING DETERGENTMIXTURES Certain charged chemical compounds like Calcium phosphates are mixed with functional cDNA of desired function. The mixture is introduced near the vicinity of recipient cells. The chemicals disturbs the cell membrane, widens the pore size and allows cDNA to pass through the cell. LIPOFECTION It is a technique used to inject genetic materials into a cell by means of liposomes. Liposomes are artificial phospholipid vesicles used to deliver a variety of molecules including DNA into the cells.
- 20. GENE AUGMENTATION THERAPY Most common form of gene therapy Foreign gene replaces missing or defective gene. Eg. Replacement of defective p53 gene by a normal one in liver cancer. GENE INHIBITION THERAPY Done to block the overproduction of some proteins. 2 types – Antigene and antisense therapy. Antigene – blocks transcription using antigene oligonucleotide Antisense – blocks transalation using antisense oligonucleotide.
- 21. Long lastingtherapy is not achieved by gene therapy; Due to rapid dividing of cells benefits of gene therapy is short lived. Immune response to the transferred gene stimulates a potential risk to gene therapy. Viruses used as vectors for gene transfer may cause toxicity, immune responses, and inflammatory reactions in the host. Disorders caused by defects in multiple genes cannot be treated effectively using gene therapy.
- 22. Gene therapyhas the potential to eliminate and prevent hereditary diseases such as cystic fibrosis, ADA- SCID etc. It is a possible cure for heart disease, AIDS and cancer. It gives someone born with a genetic disease a chance to life. It can be used to eradicate diseases from the future generations.
- 23. Who willhave access to therapy? Is it interfering with God’s plan? Should people be allowed to use gene therapy to enhance basic human traits such as height, intelligence etc.? Is it alright to use the therapy in the prenatal stage of development in babies?
- 24. Theoretically, genetherapy is the permanent solution for genetic diseases. But it has several complexities. At its current stage, it is not accessible to most people due to its huge cost. A breakthrough may come anytime and a day may come when almost every disease will have a gene therapy Gene therapy have the potential to revolutionize the practice of medicine.
- 25. In anew gene therapy method developed by University of Florida in Jan 2012, researchers found treatment for a common form of blindness ( X- linked retinitis pigmentosa ) that strikes both youngsters and adults. A gene therapy called NLX-P101 dramatically reduces movement impairment in Parkinson's patients, according to results of a Phase 2 study published on March, 2011 in the journal Lancet Neurology.
- 26. Dubey R.C,A textbook of biotechnology, 1st edition(2004), S Chand and company, New Delhi Gupta P.K, Elements of Biotechnology, 1st edition(2001), Rastogi Publications, Meerut. Satyanarayana U, Biotechnology, 1st edition, Book and allied (P) Ltd, Kolkata. http://www.medindia.net/articles/genetherapy_treat ment.htm http://en.wikipedia.org/wiki/Gene_therapy