How Gene Therapy Works

April 27, 2000 -- Proteins do everything. They think our thoughts, remember our memories, shoot our hoops, enjoy our music. They make our bodies, every organ in our bodies, every tissue and cell in those organs, and every functioning part inside every cell in our body. Everything -- at least from a biological perspective.

Proteins make the carbohydrates and fats that our bodies use, they break them down and rebuild them depending on what our bodies need. They make the hormones and use the vitamins. Yes, proteins do everything. So the obvious question is, what makes the proteins?

Well, proteins make proteins, but they make it on the basis of information they get from DNA. The DNA is arranged into genes, which are arranged into chromosomes, and can be seen as a sort of 'library' for making proteins. Every time the body needs a protein, it sends other proteins to this library, and the proteins search for the correct section of the library (the chromosome) and the correct book and correct page (the gene).

The proteins make a 'photocopy' of this gene (this 'photocopy' is called RNA), then use that copy to make the protein they are interested in making. Disease can be seen as being caused by a misprinted 'page' in the DNA 'library,' which ends up making faulty proteins. The faulty proteins don't function properly and cause disease. These diseases are, for the most part, what we call genetic or inherited diseases.

Another way disease can happen is when the body's natural defense mechanisms or regenerative powers are overwhelmed. While the body has the ability to fight bacteria, for example, when there are too many bacteria to fight, we get sick. Or when you break a bone: even though bone cells have the ability to regenerate, the break is too big and the body needs help.

The help, of course, is medical treatment. Gene therapy involves restoring the normal functioning proteins to the body, usually by putting in the correct gene. In other words, it means putting in the right protein at the right time in the right place. It could also be called "protein therapy" or "molecular therapy," but the name "gene therapy" has stuck. One reason for this is that inserting the correct gene means that the body can keep on making the needed protein as long as those cells live. The gene, then, is the gift that keeps giving, and this therapy has advantages over just administering a protein or a molecule.

Scientists have devised several ways to put a gene in the body, from placing the correct gene in a virus and infecting the person with that virus, to placing the gene into cells and then putting the cells back into the body.

Most proposed gene therapy treatments right now involve genetic diseases. But the other type of diseases, in which the body has been overwhelmed, can also be treated genetically -- by putting in greater amounts of the genes that are needed to fight the bacteria or regenerate the bone.

Potentially, gene therapy could be used to treat most, if not all, diseases. All medical treatments up until now have been external, whether the surgeon removes or repairs something, or the internist administers a drug that is usually alien to the body, or the psychiatrist improves a patient's mental state through psychotherapy. Most of these treatments do not address the problem directly and specifically. That's why the number of diseases we can actually cure is quite small.

Gene therapy, on the other hand, is internal. For the most part, it uses genes and proteins that are a part of nature and our bodies, and which nature intended for the use we are putting them to -- to cure disease.

That is what makes the story of the "bubble" children so important. Scientists have taken a very serious disease, in which these kids could not live outside of their protective "bubbles," and cured it by correcting the problem in the body itself.