A top anti-aging scientist at Harvard described the group's first study as "a major breakthrough in aging research." He called their follow-up work "a tour de force."
The research team he was referring to made the discovery that aging can be controlled within a certain area of the brain. They believe this has the potential, not only to slow down the aging process, but to also treat age-related diseases.
Like other important advances in this field, it all hinges on the activity of stem cells.
The Role of The Hypothalamus
The hypothalamus is an area of the brain of major importance. It produces many hormones that control growth, reproduction and metabolism.
Previous studies suggested that the hypothalamus controls a number of aspects of aging. A research team from Albert Einstein College of Medicine in New York set out to see if this was really the case.
They did so by tracking the activity of NF-kB in the brains of mice. This protein affects how DNA behaves and reproduces, and is involved with inflammation and stress.
They discovered that it became more active in the hypothalamus as the mice grew older.
The researchers found that when middle-aged mice were injected with a substance that inhibited NF-kB in certain immune cells in the hypothalamus, they performed better than a control group of mice on tests of cognition and movement, and experienced less age-related decline in bone mass, skin thickness and muscle strength.
In contrast, mice that were given a chemical that stimulated NF-kB died sooner.
Now that the role of the hypothalamus was confirmed, it was time to investigate further.
Could Add a Dozen Years to Human Life
In the most recent study published in Nature in August, the New York team carried out a series of experiments.
In the first, they demonstrated that neural stem cells -- found in a small number of brain regions at birth -- diminish in the hypothalamus over time. By old age most of the cells have gone.
To find out if this was a cause or effect of aging, they used a toxic agent to destroy nearly three-quarters of hypothalamic stem cells in the mice. In the months that followed, the mice performed worse on a battery of tests and aged far more rapidly compared to controls.
Next, they injected old mice with neural stem cells from newborn mice. This allowed them to be healthier and live 15% longer than the control group, the equivalent of about 12 years in human terms.
Now certain these stem cells could influence aging, they ran further tests to determine the mechanism for bringing this about.
Replenished Stem Cells Reverse Aging
They found that certain peptides which play important roles in the regulation of gene expression -- microRNAs -- are released from the neural stem cells and flow into cerebrospinal fluid. These were found to be responsible for most of the anti-aging effects.
This was confirmed when extracted microRNAs were injected into the cerebrospinal fluid. The researchers again observed significantly reduced measures of aging.
Dongsheng Cai, the lead researcher on the whole series of experiments said, "...the effects of this loss [of stem cells] are not irreversible. By replenishing these stem cells or the molecules they produce, it's possible to slow or even reverse various aspects of aging throughout the body."
In the view of Dr. David Sinclair, Professor of Genetics at Harvard Medical School, “It is a tour de force. It’s a breakthrough. The brain controls how long we live. I can see a day when we are implanted with stem cells or treated with stem cell RNAs that improve our health and extend our lives."
Dr. Cai believes that so long as these mechanisms are fundamental to life, similar treatments should produce positive results in people. His research group hopes to launch human trials to find out.
