- MONDAY, Aug. 11 (HealthDay News) — An experiment that improved
the natural cellular garbage-disposal system in mice made old liver cells
act young again. And the same rejuvenating effect might be possible one
day in the brain and other body parts of humans, researchers report.

“We studied one of the systems that remove damaged proteins,” said
study leader Dr. Ana Maria Cuervo, an associate professor of developmental
and molecular biology at Albert Einstein Medical College in New York
City.

This system handles about 30 percent of the cells' damaged proteins,
escorting them to inner cell structures called lysosomes, where enzymes
break the proteins down. Studies by Cuervo have shown that the disposal
system becomes less efficient as cells grow older. They've also pinpointed
the reason for the age-related decline — a loss of receptors on the
surface of the lysosomes that causes a buildup of damaged proteins in the
cell.

For the study, Cuervo did some genetic engineering, creating mice with
an extra gene for the lysosome receptors. The extra gene was added only to
liver cells and was turned on only when the mice reached middle age. When
the mice were examined at 22 to 26 months of their life — equivalent to
80 years for a human — “the liver cells were able to maintain the same
level of activity as when they were young,” Cuervo said. “They removed all
damaged oxidized proteins.”

To test whether improved protein clearance in liver cells helped
overall liver function, Cuervo injected a muscle relaxant into very old
mice who had the added gene. Those mice metabolized the relaxant as
quickly as normal young mice.

The experiment was “a proof of principle,” Cuervo said, and she is
moving on to work with brain cells. She said she's working with an animal
model of Parkinson's disease, “and we hopefully can prevent brain
deterioration.”

Most people who develop Parkinson's disease or Alzheimer's disease are
born with a mutation that gives rise to defective proteins late in life,
Cuervo said. Improving the cellular protein disposal systems in brain
cells might delay the onset of the conditions, she said.

Genentic engineering might not be needed to achieve the anti-aging goal
in humans, Cuervo said. “As we understand why this system decreases with
aging, we are trying to identify compounds that do the same thing,” she
said. “Also, we are looking at dietary manipulation. Some modifications in
the diet might do the same thing.”

The findings were published Aug. 10 in the online issue of the journal
Nature Medicine.

Dr. Ronald Klatz, president of the American Academy of Anti-Aging
Medicine, called the new study “another piece of evidence supporting the
contention that aging is a reversible condition. We can not only slow
aging, but also reverse many forms of aging.”

Klatz acknowledged a feeling of disappointment that genetic engineering
was required to achieve the anti-aging effect in the test animals. But, he
added, “From the pure science point of view, it is impressive.”

More information

Learn about lysosome function from the U.S.
National Library of Medicine.