There are many diseases that bears and other hibernating animals should avoid, including blood clots, bedsores, and bone loss. So doctors and veterinarians are investigating their ability to sleep deeply.
Flaubert, a doctor who usually works at Sweden's Orebro University Hospital and Denmark's Aarhus University, traveled to Sweden's bear country by snowmobile and snowshoes to find out how bears manage to snooze during the long winter months. I was thinking hard to answer the question, “Can I survive without dying?”
There are a number of illnesses that bears and other hibernating animals should avoid during torpor, including blood clots, bedsores, bone loss, and muscle weakness.
That's why doctors and veterinarians around the world are investigating hibernators' deep sleep abilities and using that insight to develop drugs to treat cardiovascular problems and other illnesses in people. Flaubert's work to unravel the mysteries of bear blood is just the latest in a series of studies on bears and other hibernating animals. Space agencies and even the military are pouring money into hibernation research in hopes of discoveries that will help astronauts endure the rigors of space travel or treat injured soldiers.
“We can learn so much from nature,” says Manuela Thienel, a cardiologist at the Ludwig-Maximilians-University in Munich who collaborated with Flaubert and led recent research on hibernating bears. said. “It's a lot more than we think.”
Because so many drug trials and other medical studies focus on testing treatments in laboratory rats and mice, this research is being done in ways that are not traditionally studied in hopes of developing new drugs. It's part of a movement to gain insight into the strange mechanisms of animal bodies that never existed. For humans.
“I was a little tired of the way we traditionally do medical research,” Flaubert said, starting with a disease and experimenting on mice and rats to find a cure. “With bears, it's the opposite,” he says.
Hibernating brown bears “are animals that don't get sick, but they should get sick,” he said. “This is a living library of biological solutions.”
“We were onto something.”
Brown bears are serious about their sleep. The furry giants can hibernate for up to eight months after gaining weight in the fall.
But no matter how tired a person is, if a person tries to sleep for that long, his muscles atrophy and he becomes ugly. Your bones will become weaker. Bedsores develop and the skin crusts over.
In fact, hibernation is not a type of actual “sleep” as people experience it. It's more extreme. It is a state of deep energy storage due to the brown bear's heart rate. drop Less than 10 beats per minute.
Flaubert's interest as a cardiologist was blood. For humans, just taking a transatlantic flight increases the risk of blood clots. But when the bears emerge from their dens after months of snoozing, they're healthy and free of blood clots.
To find out why, he and Tienel teamed up with bear researchers in Sweden. The team tracked 13 bruins by helicopter during the summer and stalked their burrows during the winter to sample their blood. Once, a bear briefly woke up while trapping experts were removing it from a stream.
Because blood cells deteriorate rapidly outside the body, centrifuges and other laboratory equipment had to be moved from Germany to a house in the Swedish countryside for analysis. “When you're working with blood and platelets, you have to work very fast,” says Tobias Petzold, another cardiologist involved in the project.
The study was successful in finding that certain proteins, specifically one called HSP47, were found in much lower amounts in bears' blood in winter than in summer, the paper said. published It was published in Science magazine earlier this year.
This protein, which appears on the surface of platelets, helps blood cells stick together. When a blood clot forms after a cut, it stops bleeding in the body and aids in healing. However, if blood clots in the veins and does not dissolve on its own, blood clots can be fatal.
To see if the protein had the same effect in humans, the researchers looked at people with spinal cord injuries. These patients, like hibernating bears, had fewer blood clots, suggesting that their bodies found a way to reduce the presence of the protein after the injury.
The research team found that HSP47 levels in these patients were much lower than in uninjured people. The same was true for penned pigs and participants in bed rest studies.
“We were onto something,” Flaubert said.
Other animals have even more extreme hibernation than bears.
Every fall, 13 ground squirrels burrow into the soil, curl up into little fur balls, and go to sleep. But unlike brown bears, these rodents, which are found throughout the Great Plains, experience a sudden drop in body temperature to below freezing during hibernation. It shakes the sleep every week or two and then gets cold again.
This led veterinarian and scientist Ashley Zehnder to wonder: Do squirrels repair themselves many times after nearly freezing to death?
she Colleagues at Fauna Bio, the company she co-founded, examined heart tissue taken at different times during hibernation. The researchers discovered a gene that is activated in squirrel cells to protect and repair the heart when body temperature returns.
Fauna Bio is testing a compound aimed at mimicking that response in humans as a drug that could help improve heart function after injury, with the aim of starting clinical trials soon. There is.
“We're definitely seeing more people taking a critical look at how data from all kinds of different species can be used to improve human health,” Zehnder said.
Rats and mice, purchased from breeding factories and easy to care for, have become the industry standard for medical research, with successive studies using the same animals.
but Plummeting genome sequencing costs and expanding data sharing have led to a boom in research beyond so-called model organisms, such as lab rats and other animals commonly studied in science. For example, earlier this year More than 100 scientists constructed and analyzed the genomes of 240 mammals to understand human disease.
But there is great pressure to continue using traditional laboratory rodents. “I can't tell you how many times those of us who study hibernation have been asked, 'Maybe we can't do this in a mouse model?'” said Hannah Carey, a professor emeritus at the university. Told. The University of Wisconsin-Madison also studies hibernating ground squirrels.
One big problem, she added, is that laboratory rodents are often inbred. “How close will they get to wild conditions?”
in Another paper published last year in ScienceCarey and her colleagues discovered that the squirrel's gut microbes recycle waste chemicals, turning them into amino acids that the animals use to maintain muscle.
The discovery raises the possibility that probiotic supplements could not only help the elderly and those with weakened muscles due to malnutrition, but also help astronauts maintain their strength in weightlessness.
NASA and other space agencies funded hibernation research The hope is to put space travelers into a hibernation-like state to withstand long missions and cosmic radiation.No one knows why, but hibernators radiation resistant.
“This is an exciting time for hibernation biology,” Carey said. “People from outside the traditional hibernation world want to come in and collaborate.”
It was difficult at first for Flaubert. The idea was to obtain funding for brown bear research given the “embedded conservatism in the medical research community.” But in the end, his team collaborated with both NASA and the German Aerospace Center.
His team is currently searching for chemicals to develop new blood-thinning drugs that have fewer side effects than existing drugs. Developing a new drug could take five to 10 years, the researchers said.
“We need space for these crazy projects,” Flaubert said.
This article is part of Animalia, a column that explores the strange and fascinating world of animals and the ways we appreciate, risk, and depend on them.
