The Elusive Immortality Gene: Too Good to Be True?
In just three easy steps, you can become immortal.
Step 1: Make friends with a good scientist.
Step 2: Convince the scientist to include you in a human trial of an enzyme called telomerase.
Step 3: Rethink your retirement plans. With death out of the picture, you're probably going to have to work a lot longer — or make a lot more money.
If this sounds too good to be true, it is.
Time magazine called telomerase "The Immortality Enzyme" and CNN dubbed it the "Cellular Fountain of Youth," but experts are saying consumers may have misinterpreted press coverage.
"There's been a lot of media hype saying [telomerase] is going to make us all live forever," said Dr. Jerry W. Shay, professor of cell biology at University of Texas Southwestern Medical Center. "No scientist is saying that."
The reason telomerase has gotten scientists' attention: It seems to help individual cells to keep regenerating indefinitely, providing hope for degenerative diseases from muscular dystrophy to liver disorders.
How It Works
Telomerase is an enzyme that helps restore the ends of chromosomes, or telomeres. Telomeres, which get their name from the Greek word telos, or "ultimate end," and "meros," meaning "part," become shorter every time a chromosome copies itself. The ends are eventually worn down to nothing, and the chromosome can no longer copy itself.
At birth, telomerase acts on the ends of chromosomes, rebuilding them to keep cells dividing. Soon afterwards, it is turned off in most cells. But when scientists have added telomerase to cell cultures, they have found that cells can keep dividing indefinitely; in other words, they become immortal.
So, if we can find a way to turn telomerase back on in our cells, can we turn back the biological clock to day one?
Unfortunately, aging is more complex than that. "It's very unlikely that telomerase biology will account for more than 15 percent of aging," said Shay. "There are many cells that don't [regenerate] throughout life," such as cardiac and neuronal cells, so these cells are not going to be aided by a process that helps them keep dividing and regenerating indefinitely, he explained.
But 21st century medicine can use telomerase to help with that 15 percent of aging and disease caused by worn-out telomeres. Retinal eye cells, the inner coating of veins and arteries, muscle cells, and pancreas cells are all potential targets for telomerase tissue engineering.
Scientists could take a cell from one of these areas and regrow tissues in culture using telomerase. Then they could use the new tissue to replace worn-out tissue. This tissue replacement could eventually replace organ transplants: It could be easier because a person is highly unlikely to reject their own tissue, while organ recipients have to take special medication to keep them from rejecting the transplant organs.
Telomerase could also help children with muscular dystrophy, in which a genetic defect causes muscle fibers to break down. If scientists can remove these cells, rejuvenate them with telomerase and fix the defective gene in these cells with the normal gene, then implant them in children's muscle fibers, they may be able to cure this disease.
A paper published in this month's Nature called into question these possibilities when it reported that adding telomerase to cells in culture could activate a cancer-causing gene. But this cellular malfunction was not just caused by the telomerase, Shay insisted, and many other studies have shown that telomerase can be activated without turning on cancer genes.
Meanwhile, researchers are also experimenting with ways to turn off telomerase in cancer cells.
Cancer cells, unlike regular cells, have the telomerase permanently turned on so the cells keep dividing and growing until they kill their host organism. "But if you give them a telomerase inhibitor, cancer cells keep trying to divide in the absence of telomerase," and then kill themselves doing this, said Kathleen Collins, a University of California-Berkeley biochemist who is studying the basic mechanism of telomerase.
In the future, people with cancer could take a single pill to turn off the telomerase throughout their body. Since the cancer cells need telomerase more than other cells, they would die off more quickly. Once the cancer died, telomerase inhibition therapy would be discontinued.
"Telomerase inhibition as a cancer therapy has huge potential to increase human life," even more than activating telomerase, said Collins. "We usually don't die of a lack of cells. We die of disease."