Stem Cells in the Hypothalamus Slow Aging in Mice

Barsaba Taglieri
Luglio 27, 2017

What the brain tells the body can accelerate aging and shorten lifespan. That much is already clear from recent studies on neuroendocrine interactions between the central nervous system and the periphery. Yet this brain region's cell-level contributions to aging regulation have been unclear.

Now those scientists have discovered that a tiny population of stem cells situated inside the hypothalamus could hold the key to how the body regulates aging.

Scientists have found brain cells thought to control ageing, and were successfully able to reverse the process of getting older when replacing these old cells with new cells.

"But we also found that the effects of this loss are not irreversible". A new study suggests it's also responsible for keeping us young, thanks to a supply of neural stem cells that regulate our ageing.

Having proved that it was neural stem cells that were important for ageing, the scientists ran further tests to work out what the cells were doing.

"Each mouse model consistently displayed acceleration of ageing-like physiological changes or a shortened lifespan", wrote the article's authors.

As the number of stem cells began to diminish when the mice reached about 10 months, which is several months before the usual signs of aging start appearing, and by old age (about two years in mice) most of those cells were gone. The researchers wanted to understand more about how this region of the brain drives aging and what role hypothalamic neural stem cells might play in that process, so they undertook a series of experiments. So they observed what happened when they selectively disrupted the hypothalamic stem cells in middle-aged mice.

Dongsheng Cai, senior author, said: "Our research shows that the number of hypothalamic neural stem cells naturally declines over the life of the animal, and this decline accelerates aging".

According to him, if the stem cells are destroyed, the aging of the mice gets faster.

To test whether the decline in stem cells was causing ageing, and not itself a result of old age, the researchers injected mice with a toxin that wiped out 70 per cent of their neural stem cells.

Even though the working of the stem cells microRNAs is not known, Cai says that they seem to decrease inflammation and biological stress. "Mechanistically, hypothalamic stem/progenitor cells contributed greatly to exosomal miRNAs in the cerebrospinal fluid, and these exosomal miRNAs declined during ageing, whereas central treatment with healthy hypothalamic stem/progenitor cell-secreted exosomes led to the slowing of ageing". Three or four months later, the researchers compared a variety of aging-related measures, including muscle endurance, coordination, social behaviors, novel object recognition, and cognitive performance, between mice injected with the virus and various control groups of mice that received a brain injection of some sort but in which the toxin could not be produced and the hypothalamic stem cells were consequently not ablated.

The researchers are now trying to identify the particular populations of miRNAs 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 age-related diseases.

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