Aging and Gene Therapy
Aging itself is not a disease as is hemophilia, but it refers to all of the individual effects of the body in various locations which together cause humans to eventually die. Aging is a very complicated and ill understood series of failures in the human body that can be treated only by repairing and restoring these deficient components. The two areas of aging yielding the greatest results to gene therapy are reversing age-related muscle loss and reviving aged-brain cells.
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A project funded by the National Institute of Health in 1999 revealed a technique that can be used to reverse the loss of muscle mass in humans. The cause of muscle deterioration is know to stem from the fact that muscles lose their ability to signal satellite cells for repairs on damaged muscle fibers. Knowing that the satellite cells merely provide insulin-like growth factor-1 (IGF-1) and other signaling proteins to work on the impaired muscles, researchers developed a viral vector that would alter the genetics of the muscles to send a chronic signal to the satellite cells. These continually active satellite cells are then more responsive and repair damage more completely without the side affect of causing the muscles to become overly bulky as seen with steroid usage.
Douglas Skrecky from the North Dakota State University had reached similar findings through injections of growth hormone into mice. The resulting signs of rejuvenation are reduction of adipose tissue, as well as increases in growth hormone insulin-like growth factor 1, muscle mass, bone density and skin thickness. Research into muscle restoring is also being applied to find a cure for amyotrophic lateral sclerosis (ALS) and methods of prevented muscle loss during long periods of inactivity such as space travel and those incapacitated due to accidents.
Picture of Rhesus monkey
A study conducted by Dr. Mark H. Tuszynski of the University of California, San Diego showed that it is possible to revive aged-brain cells back to their "youthful vigor" using gene therapy. Using elderly Rhesus monkeys with an average age of 23 (60-70 human years old), the researchers found that the control neurons in the basal forebrain were the most affected by aging. They found that 60% of these neurons had atrophied and 40% had stopped producing the regulatory chemicals needed for the appropriate flow of information in the central cortex. However, by inserting genes for the nerve growth factor, NGF, Tuszynski was able to revive 92% of the control neurons to within 3% of their original capabilities.
Further testing is being carried out to discover whether or not reviving the brain cells actually reinvigorated the monkeys' thought processes or just provided superficial repairs. The researchers also require FDA approval before they can begin applying the gene therapies to Alzheimer's disease. Gene therapy has shown that it is plausible to correct some of the failing components of the human body, but far more research is needed before humans can live forever.