In September of 1990, the first gene therapy clinical trial approved for use in a human was carried out, led by American physician, W. French Anderson, MD. It was an exciting time for scientists, patients, and pharmaceutical companies, all of which were poised to benefit from this new and exciting scientific discovery. However, in 1999, the death of a gene therapy trial patient, 18-year old Jesse Gelsinger, sparked a huge backlash, and, since then, the industry has experienced alternating waves of enthusiasm and reservation towards gene therapy.

In the last decade, however, it seems as though attitudes towards gene therapy have taken a turn for the better. Research into this treatment option is expanding rapidly, and, with new and exciting advances in genetics, there are hopes that the first FDA approved gene therapy option is on the near horizon.

But what exactly is gene therapy, how does it work, and how do patients stand to benefit?

First developed in 1972, gene therapy involves altering the genes inside a body’s cells to treat or cure a disease. This is done by inserting a gene into a cell in order to replace, alter, or supplement a gene that is either absent from the cell, or behaves abnormally within the cell, and whose absence or abnormality is responsible for a disease.

However, usually a gene that is inserted directly into a cell does not function. Because of this, there is a broad range of tools that have been developed to assist with the genetic transfer. The most common tool is known as a vector, which is a carrier that is genetically engineered to deliver the gene into the cell. Vectors are usually viruses, because a virus can recognize cells and carry genetic material into a cells’ genes. The viruses must be modified so that the disease-causing genes are removed and, therefore, cannot cause the spread of the disease when used in people. The vector can either be injected or given intravenously into a specific tissue in the patient’s body. Alternatively, a cell can be removed before being exposed to the vector in a laboratory and then returned to the body.

A gene can also be delivered into a cell within small synthetic “envelopes” of fat molecules. Because cell membranes contain a high concentration of fat molecules, the “envelope” can easily pass through the membrane and carry the therapeutic gene into the cell as if it were one of the cell’s own molecules.

A third way genes can be entered into cells is through a technique called electroporation. This involves applying an electrical charge to the cell, which will create small openings in the surrounding membrane. Once open, the genes can pass through.

Although these tools have been slow to develop, and despite the fact that the technique remains risky and is still under study to ensure that it is safe and effective, gene therapy holds a lot of promise for patients.

Initially, gene therapy was only considered for treating monogenic diseases, i.e. hereditary diseases that stem from a single defective gene. However, this treatment option is now being developed for a wide array of disease types, especially those that are widespread and prevalent like cancer. Furthermore, gene therapy is intended to be a one-time treatment, meaning that patients with diseases such as hemophilia and diabetes, who are required to undergo repeated injections in order to manage their disease, will no longer have to endure such an invasive and involved treatment regime. And finally, gene therapy has the potential to correct a disease at its most basic level and, thereby, provides a method to cure, not just ease a disease.

Most likely, we will still have some time to wait before we can judge whether the reality of gene therapy will live up to all the hype. But, before long, gene therapy companies could very well be leading the way in treating and curing the world’s most devastating diseases.