Gene Therapy

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GENE THERAPY

• BY
• KARTHIKA DEVI B
• LDC

2
INTRODUCTION

• It is a technique for correcting defective genes
  that are responsible for disease development

There are four approaches 1.A normal gene
inserted to compensate for a nonfunctional
gene. 2. An abnormal gene traded for a normal
gene. 3. An abnormal gene repaired through
selective reverse mutation. 4. Change the
regulation of gene pairs
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How DOES GENE THERAPY WORK?

• A vector delivers the therapeutic gene into a
  patients target cell
• The target cells become infected with the viral
  vector
• The vectors genetic material is inserted into
  the target cell
• Functional proteins are created from the
  therapeutic gene causing the cell to return to a
  normal state.
• Two Approaches
• Ex vivo
• In vivo

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Ex vivo gene therapy

• Cells from diseased person are removed
• Then, they are treated in lab (using techniques
  similar to bacterial transformation)
• Finally, they are reintroduced to the patient

• More effective than in vivo
• Transfection is the introduction of DNA into
  animal or plant cells.

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In vivo gene therapy

• Introducing genes directly into tissues or
  organs without removing body cells
• Challenge is delivery only to intended tissues
• Viruses act as vectors for gene delivery, but
  some injected directly into tissue

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Viral vectors

• Viral vectors use viral genome to carry
  therapeutic gene(s) and to infect human body
  cells
• Adenovirus (common cold)
• Adeno-Associated Virus
• Retrovirus (HIV)
• Herpes simplex virus (cold sores)

• Targeted gene therapy may result since some
  viruses infect certain body cells

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• Adenoviruses infect both dividing non-dividing
  cells effectively
• Adeno-Associated viruses do not cause illness in
  humans, can infect a wide variety of cells,
  integrate 95 of time in same location
• Retroviruses are of interest because they insert
  DNA into the genome of host where it remains
  permanently (integration), but often, randomly

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• Cont.

• Herpes virus (HSV-1) strain primarily affects
  central nervous system (CNS)
• May help develop treatments for Alzheimers,
  Parkinsons, and other genetic neurodegenerative
  diseases
• However, although viral vectors may help, most
  human cells are not easily transfected

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Non-viral vectors

• Methods for Non-Viral gene delivery have
  explored using Physical and Chemical approaches.
• Physical
• Microinjuction
• Electroporation
• Gene gun
• Chemical
• Lipplexes
• Polyplexes

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LIPOPLEXES

• The lipid-DNA complex are referred to as
  Lipoplexes orLiposomes.
• They have a DNA construct surrounded by
  artificial lipid bilayer.
• They are non-toxic and non-immunogenic.
• The DNA taken up by the cells, is get degraded by
  liposomes.
• The efficiency of gene delivery is very low.
• 3 Types of Lipids
• Anionic
• Neutral
• Cationic

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POLYPLEXES

• Complexes of Polymers with DNA are called
• Polyplexes.
• Polyplex is consist of cationic polymers their
  production is regulated by inonic Interactions.
• Large Difference compared to lepoplexes is
• That the polyplexes cannot release their DNA
  Load
• into the cytoplasm.
• Co-transfection with endosome-lytic Agents such
  as inactivated Adeno Virus must occur (To type
  the endosome that is made during endocytosis the
• process by which the polyplex enters the cell).

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Advantages

• Live a chance of a normal life to baby born with
• Genetic Disease.
• Live hope of healthy life to cancer patient .
• For certain disease that do not have any cure
  except gene therapy,it could save many lives

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DisAdvantages

• The Genetic testing ,Screening research in
  finding the availability of certain gene is very
  controversy.
• May increase rate of abortion if prenatal tet
  regarding baby with Genetic Disease is done.
• The cost is very high the patient might need an
  insurance to cover the treatment.

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CONCLUSION

• Theoretically, Gene Therapy is the permanent
  solution for genetic diseases.
• But, it is not as simple as it appears since it
  has several inbuilt complexities.
• It broadly involves isolation of specific gene,
  making its copies, inserting them into target
  tissue cells to make the desired protein.
• It is absolutely essential to ensure that the
  gene is harmless to the patient and it is
  appropriately expressed.
• And it is appropriately expressed.

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REFERENCE

• Nancy Smyth Templeton, Danilo D. Lasic, Gene
  Therapy-Therapeutic Mechanism And Strategies,
  California.
• Ranga M.M-Animal Biotechnology, third
  edition,2007,Agrobias publication.
• http//www.genetics.edu.au/information/genetics/Ge
  netherapy/257.
• http//mayoclinic.com/Genetherapy/vectors.html.