THURSDAY, Aug. 25, 2005 (HealthDay News) -- It's your routine visit to the doctor in 2020. There's the blood pressure check, the standard vision tests, and, oh yes, your anti-aging shot.
Such a possibility -- an injection of a hormone to extend life -- has come a little closer to reality with the release of a new report that found that a hormone made by a gene called Klotho suppresses aging in mice.
It's a long way from here to there, said Dr. Makoto Kuro-o, lead author of the paper on the mouse study that appears Thursday in the online edition of the journal Science. But humans do have an almost identical version of the Klotho gene that is carried by mice, and "some studies show that variations of the Klotho gene are associated with extended life in humans," Kuro-o said.
The Klotho gene is named for the Greek goddess who supposedly spun the thread of life. Kuro-o, then working in Japan, was among a group of scientists who first identified the gene in 1997 in a mutated form that accelerated age-dependent loss of function in mice.
Subsequent studies in the United States showed that people who carried two copies of a less-common form of the gene tended to die earlier than those who had the more common gene.
In the new study, a group led by Kuro-o, now an assistant professor of pathology at the University of Texas Southwestern Medical Center at Dallas, created transgenic mice with overactive versions of the Klotho gene. Those mice proved to have life spans 20 percent or more longer than mice with the ordinary version of the gene, Kuro-o said.
"These are still animal experiments, but potentially it might be possible to use the hormone in humans," he said. "But we still don't know if the protein can be used to extend life span in humans."
A lot must still be learned about the Klotho hormone, starting with the way it works, Muro-o said. "We speculate that it blocks insulin action," he said. Specifically, it appears to block the insulin-like growth factor-1 pathway. Studies have shown that blocking that pathway extends the life span of worms, flies and mice, he said, and the same may well be true of humans.
Another missing piece of information, one that Kuro-o and his colleagues are investigating now, is the receptor for the Klotho hormone, the molecule through which it makes contact with cells. "We need to know the molecular identity of the receptor," he said.
Over the long run, if everything pans out as hoped, Kuro-o envisions multiple medical uses of the hormone in humans. One would be a blood test for levels of the hormone to help determine a person's potential life span. Such a human blood test is not available now, but there is a mouse blood test "and maybe we can directly apply a version of the test in humans," he said.
Then there's the possibility of the anti-aging shot. The road ahead is a long one, with trials on a succession of animals needed to determine whether the early results with mice will hold up, and whether side effects appear, Kuro-o said.
Even if the anti-aging injection doesn't materialize, there still could be medical uses for manipulation of the Klotho hormone, Kuro-o noted. For example, high levels of the hormone have been shown to be associated with a reduced risk of atherosclerosis, the leading cause of heart disease, he said.
To learn more about aging research, visit the National Institute on Aging.