All posts by Daniel Davies

Adding stem cells to the brains of mice “slowed or reversed” ageing

Albert Einstein College of Medicine scientists “slowed or reversed” ageing in mice by injecting stem cells into their brains.

The study, published online in the journal Nature, saw the scientists implant stem cells into mice’s hypothalamus, which caused molecules called microRNAs (miRNAs) to be released.

The miRNA molecules were then extracted from the hypothalamic stem cells and injected 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 changes in the animals’ muscle endurance, coordination, social behaviour and cognitive ability.

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

To reach the conclusion that stem cells in the hypothalamus held the key to aging, the scientists first looked at the fate cells in the hypothalamus as healthy mice got older.

The number of hypothalamic stem cells began to diminish when the mice reached about 10 months, which is several months before the usual signs of aging start appearing. “By old age—about two years of age in mice—most of those cells were gone,” said Dr. Cai.

Images courtesy of the Mayo Clinic.

The researchers next wanted to learn whether this progressive loss of stem cells was actually causing aging and was not just associated with it.

To do this, the scientists observed 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,” said Dr. Cai.

Finally, to work out whther adding stem cells to the hypothalamus counteracted ageing, the scientists 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.

The scientists are now trying to identify the particular populations of microRNAs that are responsible for the anti-aging effects seen in mice, which is perhaps the first step toward slowing the aging process and successfully treating age-related diseases in humans.

Researchers discover remains of “Triassic Jaws” who dominated the seas after Earth’s most severe mass extinction event

Researchers have discovered the fossil remains of an unknown large predatory fish called Birgeria: an approximately 1.8-meter-long primitive bony fish with long jaws and sharp teeth that swallowed its prey whole.

Swiss and US researchers led by the Paleontological Institute and Museum of the University of Zurich say the Birgeria dominated the sea that once covered present-day Nevada one million years after the mass extinction.

Its period of dominance began following “the most catastrophic mass extinction on Earth”, which took place about 252 million years ago – at the boundary between the Permian and Triassic geological periods.

Image courtesy of UZH. Featured image courtesy of Nadine Bösch

Up to 90% of the marine species of that time were annihilated, and before the discovery of the Birgeria, palaeontologists had assumed that the first predators at the top of the food chain did not appear until the Middle Triassic epoch about 247 to 235 million years ago.

“The surprising find from Elko County in northeastern Nevada is one of the most completely preserved vertebrate remains from this time period ever discovered in the United States,” emphasises Carlo Romano, lead author of the study.

Although, species of Birgeria existed worldwide. The most recent discovery belongs to a previously unknown species called Birgeria Americana, and is the earliest example of a large-sized Birgeria species, about one and a half times longer than geologically older relatives.

The researchers say the discovery of Birgeria is proof that food chains recovered quicker than previously thought from Earth’s most devastating mass extinction event.

According to earlier studies, marine food chains were shortened after the mass extinction event and recovered only slowly and stepwise.

However, finds such as the newly discovered Birgeria species and the fossils of other vertebrates now show that so-called apex predators (animals at the very top of the food chain) already lived early after the mass extinction.

“The vertebrates from Nevada show that previous interpretations of past biotic crises and associated global changes were too simplistic,” said Romano.