Scientists find way to reverse aging in mice
CTV.ca News Staff
Published Monday, November 29, 2010 10:00PM EST
Scientists in Boston have made an astounding discovery, taking aging mice and turning them young again, like tiny little Benjamin Buttons.
Just like the title character in the Hollywood film version of "The Curious Case of Benjamin Button," the mice appeared to not only stop aging but grow younger.
Molecular biologist Dr. Ronald DePinho at Harvard Medical School in Boston was able to pull off the feat by playing with "telomeres" -- the protective DNA caps on the ends of our chromosomes.
The caps, which have long been implicated in aging, prevent our chromosomes from "fraying" and the genes inside them from "unravelling."
Scientists have long known that a little bit of our telomeres erodes each time our cells divide. Previous research has shown that people with longer telomeres tend to live longer, whereas those with shorter telomeres suffer more from age-related diseases, such as Alzheimer's.
A few years ago, DePinho and his research team devised a way to engineer mice so that they lacked a working copy of the gene that regulates the production of telomerase, which is an enzyme that strengthens telomeres and whose production declines over time.
Instead of dying at three years old, the genetically engineered mice died at about six months. By the time they died, they had become infertile, their coat hair had turned grey and they had developed age-related conditions such as osteoporosis.
DePinho wondered whether he could reverse the aging in the mice if they suddenly began making telomerase again.
So he took a group of engineered mice and added back the telomerase gene, but left it inactive. His team then allowed the mice to age for six months, until they were the equivalent of 80-year-old humans. They then gave the mice a drug that "switched on" the telomerase gene.
One month later, not only did the new production of telomerase stop the aging process in the mice, it appeared to actually undo the premature aging so that the mice became the physiological equivalent of young adults.
Even DePinho was surprised at how effective the experiment was.
"We expected to see a slowing or a stabilization of aging. Instead, what we found was a dramatic reversal in aging," he told CTV.
"The shrunken brains increased, new neurons were formed, the coat hair was restored to a new sheen."
DePinho notes that the treated mice went on to have a normal lifespan. They were simply healthier and biologically younger.
DePinto and his colleagues stress that the study was a "proof-of-concept" experiment, designed to show that changes to telomerase can affect aging. There are still many questions to answer before an experiment can be tried on humans.
For example, some research has shown that telomerase seems to help cancer tumours grow faster. DePinho says his team didn't observe any cancers in the mice, but then the telomerase was activated for only one month.
"This teaches us something fundamental about aging: that aged tissue -- even very aged tissue -- retains the ability to rejuvenate itself," he said.
DePinho says it's possible the method could be used to treat people with rare genetic premature aging syndromes. Whether the technique could help reverse normal aging still remains to be seen. Still, he says the findings were worth sharing and appear in the journal Nature.
"The results were so dramatic that we wanted to get them out to the research community as soon as possible so we could inspire the research community to move forward on these findings," DePinho said.