June 11--Aging mice with ailing hearts have gotten a boost from a drug
discovered on Easter Island in the 1970s, offering substantive new evidence that
the drug could help humans live longer and healthier lives, a Buck Institute
After just three months of treatment with rapamycin, the laboratory mice -- at
an age comparable to people in their 70s -- had revitalized hearts and also
spent more time on running wheels.
"It was a fairly dramatic result," said Simon Melov, a faculty member at the
Buck Institute for Research on Aging, located in Novato.
Ultrasound imaging showed the mice's hearts had become more efficient at pumping
blood, and genetic analysis identified the mechanisms responsible for the
improvement, he said.
The study, reported this week in the online journal Aging Cell, offered "the
first evidence that age-related heart dysfunction can be improved even in late
life via appropriate drug treatment," Melov said.
Scientists are in a race against the prospect that treating 78 million baby
boomers for an array of age-related diseases could double the nation's annual
health care costs to $4 trillion, with half of it spent on care for the elderly.
Heart disease, the leading cause of death in the United States, claims about
600,000 lives a year and costs about $109 billion each year.
Melov, a Petaluma resident, said there is "a real demand" for medications to
treat an aging population, an urgency that has prompted increased focus on drugs
like rapamycin that are already deemed safe for human consumption.
Several studies have found that rapamycin extends the lifespan in animals, but
Buck's is the first to demonstrate improved function, he said.
Researchers at the Mayo Clinic are recruiting elderly people with heart disease
as participants in a clinical trial using rapamycin, a study unrelated to the
Buck Institute's work.
Rapamycin is approved for use as an antifungal agent, treatment for some cancers
and to control patient reaction to transplanted kidneys.
Extending human lifespan -- currently at 78.7 years -- is of little use unless
people are relatively healthy, leading to the term "healthspan," Melov said.
"You don't want extended decrepitude," he said.
The mice given rapamycin in his study "showed remarkable improvement" in heart
function, while the untreated mice continued to decline.
His next step is to assess the impacts on mice given a year-long treatment with
rapamycin, looking for benefits to other tissues, such as bones.
In the three-month study, the mice with demonstrably stronger hearts also spent
more time on running wheels, a finding that invites speculation, Melov said.
"Maybe it's because they felt better," he said.
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