Understanding Gene Therapy

• Gene therapy is a potential method to treat or cure genetic-related human illnesses, as many human diseases relate to defective genes that are incurable by traditional medicine.
• In 2015, researchers from Harvard Medical School and Boston Children's Hospital used gene therapy to restore basic hearing in genetically deaf mice.
• The Boston Children's Hospital research team restored hearing to 25 decibels in the mice, equivalent to a whisper.
• An improved gene therapy vector called "Anc80," developed at Massachusetts Eye and Ear, was used to enable gene transfer to inaccessible outer hair cells in the cochlea.
• The first recombinant DNA experiments and realization of human gene therapy occurred in 1971.
• Gene therapy entails inserting foreign DNA into a patient's tissue to eradicate a targeted disease.
• Gene therapy is inspired by the success of recombinant DNA technology over the last 20 years, and is a promising but potentially unfavorable medical field.

Basic Process

• Approaches to gene therapy include:
  • Replacing a mutated gene with a healthy copy.
  • Inactivating a mutated gene that is malfunctioning.
  • Introducing a new gene to help fight a disease.
• Genes cannot be directly inserted into a human gene or cell.
• Genes are inserted using a carrier or vector, commonly genetically changed viruses that carry normal human DNA.
• Viruses have evolved to encapsulate and transport genes to human cells pathologically.

Types of Gene Therapy

• Gene therapy aims to correct diseases at their root by fixing abnormal genes.
• Somatic gene therapy involves manipulating genes in cells to help the patient, but these changes are not inherited.
• Germ-line gene therapy involves the genetic modification of germ cells, which will pass the change on to the next generation.
• Stem cells are mother cells that can become any type of cell in the body.
• Stem cells can self-renew or multiply while maintaining the potential to develop into other cell types.
• Stem cells can become cells of the blood, heart, bones, skin, muscles, brain, etc., and all types of stem cells have the same capacity to develop into multiple cell types.
• Stem cells are derived from embryonic and somatic sources.
• Embryonic stem cells are derived from four- or five-day-old human embryos in the blastocyst phase, typically extras from IVF clinics.
• Somatic stem cells exist throughout the body after embryonic development and are found inside different tissues.
• Somatic stem cells can be found in tissues such as the brain, bone marrow, blood, blood vessels, skeletal muscles, skin, and the liver.
• Somatic stem cells remain in a non-dividing state and can divide/self-renew indefinitely when activated by disease or injury.
• Adult or somatic stem cells are generally limited in their ability to differentiate based on their tissue of origin, but some evidence suggests they can differentiate into other cell types.

Bioethics of Gene Therapy

• Ethical issues in gene therapy include:
  • Distinguishing between "good" and "bad" uses of gene therapy.
  • Deciding which traits are normal and which constitute a disability or disorder.
  • Determining if the high costs of gene therapy will make it available only to the wealthy.
  • Considering if widespread use of gene therapy could make society less accepting of people who are different.
  • Whether people should be allowed to use gene therapy to enhance basic human traits.
• Germline therapy controversy involves genetic modification of germ cells that are passed to the next generation.
• Questions arise about the effects of gene alteration on the unborn child and subsequent generations.
• In the United States, the government does not fund research on human germline gene therapy.

Summary

• Gene therapy treats or cures genetic-related human illnesses.
• Somatic gene therapy manipulates genes in cells to help the patient but is not inherited.
• Germline gene therapy genetically modifies germ cells, passing changes to the next generation.
• Ethical issues include deciding which human traits should be altered and the potential for discriminatory effects for those who cannot access gene therapy.

Gene therapy introduces foreign DNA into a patient's tissue to treat genetic diseases. Researchers have successfully restored hearing in deaf mice using gene therapy. This method holds promise but carries potential risks.