Scientists first postulated that cellular aging was a leading cause of death for humans back in 1970. That radical theory, called the wear-and-tear theory, makes the analogy that the human body is like a machine and human cells are like machine parts. The cellular parts - primarily the DNA - are used up over time, and as a result, bodies decline and die.
But what would happen if the body could be rebuilt with new DNA, just as a PC can be retrofitted with new software? Scientists at the University of Texas Southwestern Medical Center and biotechnologists at Menlo Park, California's Geron Corp. posed this question, which naturally led to another: Would humankind be able to extend the body's life, almost indefinitely? The controversial answer, in a paper published this coming Friday in the 16 January edition of the journal Science, is a definitive "yes."
Scientists have extended the life of eye cells, in labs in California and Texas, by as much as 40 percent in a series of just-announced experiments, says Dr. Jerry Shay, a professor of neuroscience at UT Southwestern. "The news broke today and we're having a harried time here fielding all the calls," he said.
Research has shown that human cells have a limited ability to replicate, somewhere between 20 and 100 times, depending upon the type of cell and the age of the donor. This cellular life span leads to an average life expectancy in the 70s for most people.
But scientists, as part of this basic research project, introduced telomerase, an enzyme that adds back chromosomes to a DNA strand, said Dr. Calvin Harley, chief science officer at Geron Corp. This enzyme turns off, usually, just before a person dies of so-called natural causes.
As part of the research, human retinal cells were stimulated using an electric shock, which made them more permeable. Then, using a harmless virus as the delivery mechanism, the enzyme was implanted in the cells. The cells treated with the enzyme divided for an additional 20 generations, says Harley. The test cells, moreover, are continuing to divide in the lab experiments. The life span of these cells, as well as some skin cells, replicated in a recent test, has increased by at least 40 percent, he says.
"We don't know when they will stop growing. This research raises the possibility that we could take a patient's own cells, rejuvenate them, then modify the cells, as needed, and give them back to the patient to treat a variety of genetic and other diseases," said Dr. Harley, a biochemist.
This technique, being called cellular re-engineering, also has the possibility, long-term, of emerging as life-span enhancing therapy.
Researchers cautioned that the results of the experiments were still in the early stages. So consumers should not think that this is going to be the latest cellular changing therapy since liposuction. But "a large body of research indicates that telomerase is potentially ... most promising," said Dr. Manfred Baier, president of Boehringer Mannheim, another leading biotech company.
Geron is working with several potential corporate partners, which will market the anti-aging product in the coming years.
"We've replicated the tests in two different labs. So the concept is proven," says Dr. Harley. "We think we've found the cellular fountain of youth." Ponce de Leon, and the other Spanish conquistadors who came to the United States in search of that fountain centuries ago, would surely be envious.
