Gene Therapy is a direct transfer of therapeutic genes into a patient's cells that will help correct the genetic disease. The idea of being able to modify a person's DNA to treat a disease was just a dream before, but it is finally taking flight with major success stories.
Gene therapy is different from normal drugs. It does not treat symptoms but instead targets the disease to correct the underlying genetic causes. Gene therapy can do this in many ways. Someways are by replacing a mutated gene with a healthy copy that produces a functional copy, by silencing a mutated gene that is not functioning properly, or by introducing a new gene that will help fight the disease. Gene therapy can be treated in vivo or ex vivo. In vivo gene therapy simply means that the therapeutic DNA is introduced directly into the affect cells of the body. Contrarily, ex vivo gene therapy is when cells from the patient with the genetic disease are removed, normal functioning copies of the mutated gene are then inserted into the cells, then finally the cells are transplanted back into the patient. The therapeutic gene will then express normal copies of the required protein.
In March of 2017, in France, there was a teenage boy cured of his disease through gene therapy. The boy had sickle-cell anemia, which is an inherited disease of the blood of a single mutation. Sickle cell anima is a condition in which there are not enough healthy red blood cells to carry enough oxygen throughout the entire body. The boy received an experimental gene therapy that was developed by Bluebird Bio. Bluebird Bio decided on an ex vivo gene therapy approach. They began by taking cells from the boy's bone marrow and then modifying the cells by introducing a new gene to help fight the disease by preventing the blood cells from becoming sickled. When those new cells were implanted back into the boy they began to make normal blood cells. Two years after the treatment the boy's body was able to produce enough normal red blood cells, with the help of the gene therapy, to bypass any side effects of the disorder.
Another success story with gene therapy comes from a boy in Germany who has epidermolysis bullosa. Epidermolysis is a skin disease where the skin becomes very fragile and can blister easily. These blisters can arise through minor injury or friction from something as little as rubbing or scratching. This disease threatened the life of the boy so doctors in Germany were determined to save this little boy through gene therapy. The doctors decided to make new skin with ex vivo skin therapy. These doctors extracted healthy skin cells, skin that was not blistered, isolated them and, similar to that of the teenage boy from France, added copies of a healthy version of the gene. They let the cells grow into small sheet and transplanted them onto the boy’s body with only 3 surgeries.
Both of these cases correlate with the talk that Subhojit Roy gave about potentially using gene therapy to treat Alzheimer’s disease (AD). There is still a lot that is not known about Alzheimer’s disease but Roy discovered, through his experiments, that by using CRISPR/Cas9 to target certain genes like APP C-terminus in the brain of those with AD. He also discovered that it only took CRISPR 5 days to work and correctly target the APP C-terminus in the brain. By using what he has learned through his studies and other successful attempts with gene therapy maybe one day Roy could discover a way of treating AD with gene therapy.
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