Home' Trinidad and Tobago Guardian : August 15th 2017 Contents A24 body & soul
guardian.co.tt Tuesday, August 15, 2017
Scientists at Albert Einstein College of Med-
icine have found that stem cells in the brain's
hypothalamus govern how fast aging occurs
in the body. The finding, made in mice, could
lead to new strategies for warding off age-related
diseases and extending lifespan. The paper was
published online on July 26 in Nature.
The hypothalamus was known to regulate important
processes including growth, development, reproduc-
tion and metabolism. In a 2013 Nature paper, Einstein
researchers made the surprising finding that the hy-
pothalamus also regulates aging throughout the body.
Now, the scientists have pinpointed the cells in the
hypothalamus that control aging: a tiny population
of adult neural stem cells, which were known to be
responsible for forming new brain neurons.
"Our research shows that the number of hypotha-
lamic neural stem cells naturally declines over the life
of the animal, and this decline accelerates aging," says
senior author Dongsheng Cai, MD, PhD, (professor
of molecular pharmacology at Einstein.
"But we also found that the effects of this loss are
not irreversible. By replenishing these stem cells or the
molecules they produce, it's possible to slow and even
reverse various aspects of aging throughout the body."
In studying whether stem cells in the hypothalamus
held the key to aging, the researchers first looked at
the fate of those cells as healthy mice got older. The
number of hypothalamic stem cells began to diminish
when the animals reached about ten months, which
is several months before the usual signs of aging start
"By old age---about two years of age in mice---most
of those cells were gone," says Dr Cai.
The researchers next wanted to learn whether this
progressive loss of stem cells was actually causing
aging and was not just associated with it. So they ob-
served what happened when they selectively disrupted
the hypothalamic stem cells in middle-aged mice.
"This disruption greatly accelerated aging compared
with control mice, and those animals with disrupted
stem cells died earlier than normal," says Dr Cai.
Could adding stem cells to the hypothalamus
counteract aging? To answer that question, the re-
searchers injected hypothalamic stem cells into the
brains of middle-aged mice whose stem cells had been
destroyed as well as into the brains of normal old mice.
In both groups of animals, the treatment slowed or
reversed various measures of aging.
Dr Cai and his colleagues found that the hypotha-
lamic stem cells appear to exert their anti-aging ef-
fects by releasing molecules called microRNAs (miR-
NAs). They are not involved in protein synthesis but
instead play key roles in regulating gene expression.
miRNAs are packaged inside tiny particles called ex-
osomes, which hypothalamic stem cells release into
the cerebrospinal fluid of mice.
The researchers extracted miRNA-containing ex-
osomes from hypothalamic stem cells and injected
them into the cerebrospinal fluid of two groups of
mice: middle-aged mice whose hypothalamic stem
cells had been destroyed and normal middle-aged
mice. This treatment significantly slowed aging in
both groups of animals as measured by tissue analysis
and behavioural testing that involved assessing chang-
es in the animals' muscle endurance, coordination,
social behaviour and cognitive ability.
The researchers are now trying to identify the
particular populations of microRNAs and perhaps
other factors secreted by these stem cells that are
responsible for these anti-aging effects---a first step
toward possibly slowing the aging process and treating
The article is titled, "Hypothalamic stem cells con-
trol ageing speed partly through exosomal miRNAs."
The other authors are Yalin Zhang. Ph., Min Soo Kim,
PhD, Baosen Jia, PhD, Jingqi Yan, PhD, Juan Pablo Zu-
niga-Hertz, PhD, and Cheng Han, PhD, all at Einstein.
The study was supported by grants from the Na-
tional Institutes of Health. (Albert Einstein College of
Brain cells found
to control aging
Scientists have pinpointed the cells in the hypothalamus that control aging.
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