Scientists have succeeded in restarting the cell division of aging cells using low-frequency ultrasound. This also improved the physical performance of elderly mice.
Ultrasound, ultrasonic sound, which is inaudible to humans, has been found to have rejuvenating effects. Not only did the sound waves restart aging human cells, they also breathed new life into old mice. The animals performed better physically, as they showed on a treadmill, among other things. There was also an old mouse with a hunchback, who could walk normally again.
‘Is it too good to be true? I often ask myself that question,” says Michael Sheetz, a biochemical scientist at the University of Texas Medical School in the United States. He and his team are planning a small-scale human trial to find out whether the sound wave technique is safe and can help treat age-related diseases.
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Domino-effect
When cells have multiplied a certain number of times, they stop dividing. This is also called the Hayflick limit called. The cells become senescentie: obsolete. Other factors, such as toxic chemicals, can also cause cells to become senescent.
In the long run, this can lead to a domino effect: some senescent cells secrete chemicals that cause other cells to become senescent again. This is considered one of the main causes of aging and age-related diseases: as we age, there are more and more senescent cells in different places in our body.
Therefore, many scientists are looking for a way to destroy senescent cells. But maybe we don’t need to kill them: low-frequency ultrasound could help us rejuvenate these cells.
Lower than an echo
Sheetz’s team found that low-frequency ultrasound stimulates senescent cells in monkeys and humans to divide. They also no longer excrete chemicals that promote senescence. The researchers used sound waves with a frequency of 100 kilohertz, which is about five times higher than what the human ear can hear, but much lower than the 2000 kilohertz of the ultrasound of baby ultrasounds.
Normally, human cells show signs of senescence after about 15 cell divisions. After treatment with ultrasound, these cells reached 24 cell divisions without abnormal phenomena. The team is still figuring out what the new limit is.
Exceeding the Hayflick limit could be useful when culturing cells for human treatments. Sheetz also wants to sell the ultrasonic devices to other laboratories so that they can also experiment with them.
Drastic progress
In addition to human cells, the researchers have already treated whole animals. They placed mice aged 22 to 25 months in warm water so that they were at least half submerged. Ultrasound loses less power as it propagates through water, compared to air. Mice treated with ultrasound in this way performed better on physical tests than mice that had been in the warm water without ultrasound.
In some cases, the improvements were drastic, Sheetz says. One old mouse suffered from a hunchback and could not move properly. This one scored the worst on the first tests. “We treated this mouse with ultrasound, and suddenly it moved normally again. I don’t think we’re exaggerating with the word rejuvenation.’
Enigmatic effects
The team also used a luminescent dye that binds to senescent cells. This allowed them to see that the proportion of these cells in the kidneys and pancreas had decreased after the treatment. Why ultrasound produces these effects is unclear. “Certain aspects are still puzzling,” says Sheetz.
Still, he has a hypothesis. His idea is that the physical disruption of the cells by ultrasound causes a similar effect to sports or exercise. It would activate the waste removal systems, which are turned off in senescent cells.
Are the results convincing? “In general, yes,” says Jürgen Götz, an aging biologist at the University of Queensland in Australia. “But I think we need to do more research to find out what the parameters of the ultrasound are.” It will also be difficult to apply to humans, he says, because bones and lungs block ultrasound.
Ultrasonic foot baths
Götz and his team have shown that mice get better memory after treatment with high-frequency ultrasound. He is also trying to find out whether this treatment can be used in people with Alzheimer’s.
Ultrasound has been used for decades to treat a wide variety of conditions, but mostly smaller devices and high frequencies are used. The results vary. Because different types of equipment and different methods are used, it is difficult to say how effective it is. It is also difficult to compare studies with each other, says Götz.
Sheetz and his team are preparing a trial in which people with osteoarthritis are immersed in water for treatment, and people with diabetic foot ulcers are treated with ultrasonic foot baths.
Treatments that stimulate cell division could also lead to an increased risk of cancer, but according to Sheetz, there have been no indications for this in his research.