Gene Therapy

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Gene Therapy
AP Biology Unit 2
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What is Gene Therapy?

• A way to treat or cure diseases by inserting the
  correct DNA into the cell.
• Most promising for diseases caused by a single
  gene defect (ex. hemophilia)
• Still in the experimental stages
• Clinical trials have been done on humans

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The Big Picture

• Image taken without permission from
  http//www.fda.gov/fdac/features/2000/gene.html

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Ex vivo

• Means it occurs outside of the body
• Steps
• Defective cells are taken out of the patient
• Add functional gene into defective cells
• Return these cells to the patients body
• Has been used to treat hemophilia, and adenosine
  deaminase deficiencies (leads to immune system
  problems)

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In vivo

• Means it occurs in the patients body
• Insert the genes directly into the patients
  cells
• Ex. using an aerosol spray containing functional
  genes that are are mutated in cancer cells to
  treat lung cancer.
• Still in the early stages of experimentation

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Challenges

• Find appropriate vectors
• currently recombinant viruses and plasmids are
  being tested
• Make sure vectors can be taken up by human cells
  properly
• Ensure that new gene is inserted into human
  genome properly and proteins are expressed
  correctly
• Could be very problematic if it inserts itself in
  the wrong place and disrupts transcription of a
  crucial protein

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More challenges

• How to make sure the functional gene gets to all
  the cells that need it
• How to sustain the cells that got the functional
  gene cells die after a while!
• How to control how the immune system responds to
  the vector