1. GENE THERAPY
D of PG Studies

2. Objectives- Introduction Gene therapy and use Chromosome intro.
Steps of gene therapy
Types
Problems
Current status
Conclusion
References
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3. Gene & Genome-
Gene - A segment of DNA found on a chromosome that codes for a particular protein.
Humans have approximately 100,000 genes.
Genome - The sum of all genes that code for a particular organism.
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4. Genes- Are carried on a chromosome The basic unit of heredity
Encode how to make a protein
DNARNA proteins
Proteins carry out most of life’s function.
When altered causes dysfunction of a protein

5. A. What is gene therapy? Why is it used?
Gene therapy = Introduction of normal genes into cells that contain defective genes to reconstitute a missing protein product
GT is used to correct a deficient phenotype so that sufficient amounts of a normal gene product are synthesized  to improve a genetic disorder

6. Structure of a Chromosome
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7. Many human diseases are caused by defective genes Disease
Genetic defect
hemophilia A
absence of clotting factor VIII
hemophilia B
absence of clotting factor IX
cystic fibrosis
defective chloride channel protein
muscular dystrophy
defective muscle protein (dystrophin)
sickle-cell disease
defective beta globin
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8. The Beginning…
In the 1980s, Scientists began to look into gene therapy.
They would insert human genes into a bacterial cell.
Then the bacterial cell would transcribe and translate the information .
Then they would introduce the protein into human cells.
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9. What is Gene Therapy
It is a technique for correcting defective genes that are responsible for disease development. OR
The treatment of disease by either replacing damaged or abnormal genes with normal ones, or by providing new genetic instructions to help fight disease.
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10. How is Gene Therapy Carried Out?
Modification of somatic cells by transferring desired gene sequences into the genome.
Somatic cells necessary to ensure that inserted genes are not carried over to the next generation.

11. How It Works
A vector delivers the therapeutic gene into a patient’s target cell
The target cells become infected with the viral vector
The vector’s genetic material is inserted into the target cell
Functional proteins are created causing the cell to return to a normal state
A vector is a carrier molecule, usually a virus
The target cells are usually in the liver or lung
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12. How It Works…….
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13. Steps in Gene Therapy

14. The First Case,
The first gene therapy was performed on September 14th, 1990.
Ashanti DeSilva was treated for SCID.
Doctors removed her white blood cells,inserted the missing gene into the WBC, and then put them back into her blood stream. This strengthened her immune system, Only worked for a few months.
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15. Approaches: Germline therapy
A gene is inserted into the DNA of the germline cells (egg or sperm) so that the offspring of the patient will have the inserted gene.
The egg is a very large cell, relatively easy to manipulate and inject with DNA.
Inherited by the next generation.
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16. Somatic Gene Therapy
Somatic cells include all the non-reproductive cells in the human body.
Not inherited by the next generation.
e.g:- bone marrow cells, blood cells, skin cells etc.
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17. Technique of Somatic Therapy
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18. Gene transfer
Vectors - Gene therapy delivery vehicles, or carriers, that encapsulate therapeutic genes for delivery to cells.
Examples
Biological (Viral vectors, mammalian chromosomes etc)
Physical (Microinjection, Gene gun, naked ‘DNA’, Electroporation etc)
Chemical (Liposomes, Oligonucleotides etc)
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19. In vivo = delivery of genes takes place in the body
Different Delivery Systems are Available
In vivo = delivery of genes takes place in the body
Ex vivo = delivery takes place out of the body, and then cells are placed back into the body
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20. In vivo GENE THERAPY
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21. Gene therapy is a technique for correcting defective genes responsible for disease development. Researchers may use one of several approaches for correcting faulty genes:

22. Viruses Replicate by inserting their DNA into a host cell.
Gene therapy can use this to insert genes that encode for a desired protein to create the desired trait.
The virus is engineered so that it cannot reproduce.
Four different types
1) Retroviruses
2) Adenoviruses
3) Adeno-associated Viruses
4) Herpes Simplex Viruses
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23. General drawbacks of Viral Vectors
Can't "expand" to fit a piece of genetic material larger than it is naturally built to carry, some genes may be too big to fit into a certain type of virus.
Viruses can cause immune responses in patients, resulting in two potential outcomes:
Patients may get sick.
A patient's immunity to a virus may limit treatments.
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24. Non-Viral Vectors
More efficient to deliver a gene using a non-viral vector, which has fewer size constraints and which won't generate an immune response
Typically circular DNA molecules- Plasmids
Bacteria use plasmids to transfer genes from cell to cell
Easily and efficiently store and replicate genes of interest from any organism
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25. Chromosome No immune response.
Could carry a lot of information i.e one
or more therapeutic genes.
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26. Viral Vectors General advantages of viral vectors
They are very good at targeting and entering cells.
Some viral vectors might be engineered to target specific types of cells.
They can be modified so that they can't replicate and destroy the cell.
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27. Gene guns
Gene guns Isolate normal DNA fragment. Make very small spheres of a heavy metal like gold. Coat gold with DNA. Fire particles at cells at high speed so particles enter cells. May be used directly on tissues or organs in situ.
Other techniques…
a) Electoporation
b)Liposomes
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28. Problems with Gene Therapy
Short Lived
Hard to rapidly integrate therapeutic DNA into genome and rapidly dividing nature of cells prevent gene therapy for long time.
Have multiple rounds of therapy.
Viral Vectors
Patient could have toxic, immune, inflammatory response
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29. Multigene Disorders Immune Response
PROBLEMS CONT…..
Multigene Disorders
Hard to treat because need to introduce more than one gene.
Immune Response
New things introduced leads to immune response
May induce a tumor if integrated in a tumor suppressor gene because insertional mutagenesis.
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30. Current Status
FDA hasn’t approved any human gene therapy product for sale
Reasons:
In 1999, 18-year-old Jesse Gelsinger died from multiple organ failure 4 days after treatment for ornithine transcarboxylase deficiency.
January 2003, halt to using retrovirus vectors in blood stem cells because children developed leukemia-like condition after successful treatment for X-linked severe combined immunodeficiency disease.
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31. Successful Gene Therapy
Severe Combine Immunodeficiency
Infants with severe combined immunodeficiency are unable to mount an adaptive immune response, because they have a profound deficiency of lymphocytes.
Attempt of gene therapy for immunodeficiency was successful in children with severe combined immunodeficiency due to a deficiency of adenosine deaminase.
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32. cancer
Multiple gene therapy strategies have been developed to treat a wide variety of cancers.
Phase III trial for head and neck cancer Phase III gene vaccine trials for prostate cancer and pancreas cancer.
Additionally, numerous Phase I and Phase II clinical trials for cancers in the brain, skin, liver, colon, breast and kidney are being conducted .
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33. Gene Therapy in Heart Failure
Gene therapy in HF must be aimed at correcting key molecular mechanisms in cardiac tissue.
This requires,
introduction of DNA/RNA that targets specific cardiomyocyte processes that alter HF outcomes.
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34. Challenges in Gene Therapy
Gene delivery and activation.
Introducing changes into the germline.
Immune response.
Disrupting important genes in target cells.
Success requires
-efficient delivery,
- the correct gene,
-the correct cells,
-the correct tissue,
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35. Conclusion
The viral and non viral gene delivery strategies have been fairly successful in cell culture systems and animal models
The therapeutic success of GT in human still remains questionable.
With the explosive increase in the availability of information on human genome, several genetic disorder have become candidates for gene therapy.
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36. Conclusion….
The field is still at its infancy, the need of the hour is to initiate more studies in different systems on the various aspects.
In spite of various drawbacks, gene therapy is witnessing a rapid growth and hope fully the progress would continue.
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37. References
Vyas S. P. , Dixit V. K., Pharmaceutical Biotechnology 1st edition, CBS Publisher & distributors 2001, New Delhi,
D’Souza J.I. , Killedar S. J., Biotechnology & Fermentation Process 3rd edition, Nirali Prakashan Pune. 2007,
K.Sambamurthy, Ashutosh Kar.“ Pharmaceutical Biotechnology”,2nd Edn.,New Age International Publishers
U.Satyanarayana Biotechnology 3rd edition uppala author publishers.
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38. THANK
YOU