Harvard scientists have taken prematurely aged mice and reversed the toll of time – increasing the size of their shrunken brains, restoring their diminished sense of smell, and turning their graying fur to a healthy sheen.
The work is among a growing spate of efforts to understand the basic biology that underlies aging. Ultimately, scientists hope to find ways to tap into the body’s natural regenerative capacities to make people healthier and more productive in later life.
"These were animals that were really at the brink of kicking the bucket," said Dr. Ronald DePinho, director of the Belfer Institute at Dana-Farber Cancer Institute and senior author of the paper published in the journal Nature. "We were expecting to slow or perhaps stabilize the aging process. Instead, we saw a dramatic reversal in the symptoms of aging."
DePinho and colleagues genetically manipulated mice so that an enzyme called telomerase that rebuilds the caps of chromosomes, called telomeres, could be toggled on or off.
The mice aged very quickly without telomerase. Just mid-way through the normal lifespan of a mouse, their organs had atrophied, their brains had shrunk, and they had lost the ability to detect noxious odors. But when scientists used a drug to switch the gene back on for a month, many hallmarks of aging seemed to reverse. The fertility of the mice increased, their sense of smell was restored, and their organs were rejuvenated.
DePinho was careful to point out that normal aging is the product of many biological mechanisms, and telomeres are only one factor. The researchers have not tested yet whether this type of intervention will slow aging in ordinary mice, and are far from doing comparable tests in people. Next, the researchers will try to better understand precisely what causes the youthful bloom to return to the mice when the telomerase switch is flipped on, and also follow mice for a longer time to assess whether there may be a risk of cancer.
But there is great interest in the role that telomeres, the caps of the chromosomes, play in aging. Research has found that shorter telomere length is correlated with fewer years of healthy living after age 60, DePinho said. The 2009 Nobel Prize in Physiology or Medicine was awarded to three researchers, including Jack Szostak of Massachusetts General Hospital for the discovery of telomeres and the enzyme that builds them back up.
The research was supported by funding from the National Cancer Institute and the Belfer Foundation.
"We need to intensify efforts to support basic research into aging and age-related diseases -- to understand their molecular underpinnings so we can find ways to improve years of healthy living," DePinho said.
About white coat notes
|White Coat Notes covers the latest from the health care industry, hospitals, doctors offices, labs, insurers, and the corridors of government. Chelsea Conaboy previously covered health care for The Philadelphia Inquirer. Write her at email@example.com. Follow her on Twitter: @cconaboy.|
Gideon Gil, Health and Science Editor
Elizabeth Comeau, Senior Health Producer