Gene Therapy - The Future Is Here! (cont.)
Genes can also be delivered within tiny synthetic "envelopes" of fat molecules. Cell membranes contain a very high concentration of fat molecules. The fat molecule "envelope" can carry the therapeutic gene into the cell by being admitted through the cell membrane as if it were one of its own molecules.
Genes can also gain entrance into cells when an electrical charge is applied to the cell to create tiny openings in the membrane that surrounds a cells. This technique is called electroporation.
A "bionic chip"
A new "bionic chip" has been developed to help gene therapists using electroporation to slip fragments of DNA into cells. Electroporation was originally a hit-or-miss technique because there was no way to determine how much of an electrical jolt it took to open the cell membrane.
The "bionic chip" solves this problem. It contains a single living cell embedded in a tiny silicon circuit. The cell acts as a diode, or electrical gate. When it is hit with just the right charge, the cell membrane opens, allowing the electricity to pass from the top to the bottom of the bionic chip. By recording what voltage caused this phenomenon to occur, it is now posssible to determine precisely how much electricity it takes to pry open different types of cells.
Route of administration of gene therapy
The choice of route for gene therapy depends on the tissue to be treated and the mechanism by which the therapeutic gene exerts its effect. Gene therapy for cystic fibrosis, a disease which effects cells within the lung and airway, may be inhaled. Most genes designed to treat cancer are injected directly into the tumor. Proteins such as factor VIII or IX for hemophilia are also being introduced directly into target tissue (the liver).
The potential power of gene therapy
Most gene therapy for diseases such as cystic fibrosis and hemophilia has been designed only to ease, not to cure, the disease. However, the delivery of functional copies of genes provides a potential method to correct a disease at its most basic level.
Gene therapy also holds the potential to provide "patient- friendly" treatment regimens for a variety of diseases. Today, many patients with hemophilia and diabetes must have repeated injections in order to manage their disease because proteins exist in the blood stream for a limited period of time before they are degraded or eliminated. Since DNA is more stable and functions inside the cell, the delivery of genes may result in longer-term expression of the necessary proteins.
Because of its accuracy, gene therapy has the potential to eliminate cancer cells without damaging normal, healthy tissue. Furthermore, cancer gene therapies may provide alternatives when a disease does not respond to other older treatments.
The potential of gene therapy is great but, compared to its promise, the results to date are still quite limited. However, the benefits of gene therapy are believed to be on the near horizon. Gene therapy is one of the hottest areas of medical research today. (And gene therapy companies have been among the hottest in the stock market.)
The remarkable advances in genetics, including the human genome project, have opened new doors for the exploration of gene therapy. New technologies are needed to speed the progress of gene therapy. As these new technologies such as the "bionic chip" arrive, we believe that, without a doubt, gene therapy will play an increasingly important and prominent part in medicine in the decades to come.
Last Editorial Review: 9/21/2004