Brain cells control the aging of the body

American scientists from the Albert Einstein College of Medicine found that the brain’s hypothalamus play a decisive role in aging the body. The discovery, made in mice, could lead to new strategies for warding off age-related diseases and extending lifespan. The results were published on July 26, 2017 in Nature.

It is known that the hypothalamus regulates important processes, including growth, development, reproduction and metabolism. In 2013, Einstein scientists published in Nature the amazing results of discovery, according to which the hypothalamus regulates the aging of the whole organism. Now researchers have identified that this process is controlled by a small population of mature neuronal stem cells, which are known to be responsible for the formation of new brain neurons.

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

Trying to identify the cells of the hypothalamus involved in aging, scientists traced the life cycle of healthy mice. They drew attention to the fact that the number of stem cells in the hypothalamus began to diminish when the animals 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,” – says Dr. Cai.

The researchers decided to learn whether this progressive loss of stem cells was actually causing aging, and was not simply is associated with it. To do this, scientists 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 into the hypothalamus counteract aging? To answer this question, the researchers 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 rodents. In both groups of animals, the injection slowed or reversed various measures of aging.

Dr. Cai and his colleagues discovered that the hypothalamic stem cells appear to have anti-aging effects, by releasing molecules called microRNAs (miRNAs). They do not participate in protein synthesis, but play key roles in regulating gene expression. MicroRNAs are packed inside tiny particles called exosomes, which hypothalamic stem cells release into the cerebrospinal fluid of mice.

The researchers isolated miRNA-containing exosomes from hypothalamic stem cells and injected them into the cerebrospinal fluid of two groups of mice: middle-aged animals whose hypothalamic stem cells had been destroyed and normal middle-aged rodents. This procedure significantly slowed aging in both groups of animals, which was determined by tissue analysis and behavior testing, which included assessing changes in the animals’ muscle endurance, coordination, social behavior and cognitive ability.

Currently, researchers are trying to identify specific populations of microRNAs and, possibly, other factors responsible for aging, secreted by these stem cells. The results can be a first step toward possibly slowing aging and treating age-related diseases.