Scientists may have found a solution to blood clotting ailments from one of nature’s most unlikely sources, bears.

Those of us who had to sit on long flights know all too well the medical warnings that sitting inactive for hours can cause blood clots in our legs and lungs. These warnings arise from the fact that humans experiencing severe immobility caused by illness or injury are at risk of the potentially deadly condition known as venous thromboembolism (VTE).

But bears do not suffer from similar issues despite, during their winter hibernation, remaining immobile for months every year.

This caught the attention of cardiologists Tobias Petzold and Manuela Thienel at the Ludwig Maximilian University of Munich, Germany, who wanted to find out how bears avoid dangerous blood clotting.

The researchers conducted an experiment over two winters, during which they trekked through the snow to dig out and tranquillize 13 sleeping brown bears wearing GPS collars, taking blood samples. The bears were then returned to their dens to finish their winter nap.

In the following summers, they tracked the same bears and took more blood samples to determine if there was a difference in the blood composition compared to the winter-taken samples.

Petzold, Thienel and their colleagues found that a specific protein, called HSP47, was in high quantities in the bears’ blood during summer but almost absent during the winter period.

HSP47, which is the abbreviation of ‘heat shock protein 47’, is commonly found in cells of bone or cartilage, which are connective tissues for the body.

It’s also found in platelets—small, colourless fragments of cells that circulate in the blood—where it will attach to collagen, helping the platelets bond.

Platelets also form blood clots when they recognize damaged blood vessels, which aids healing when the body responds to a cut or other injury. However, it is dangerous when a clump of platelets blocks blood flow to the lungs.

Following this discovery,  the researchers sought to confirm that the protein HSP47 was behind the bears’ lack of blood clots, so they performed laboratory tests on mice and found those lacking the protein in question had fewer clots and lower levels of inflammation than those with HSP47.

Further, similar results were observed in pigs where sows that had recently given birth and tended to remain mainly immobile for around 28 days to feed their piglets also had lower protein levels when compared to non-nursing pigs.

Similar results were also noticed in humans, with people with long-term immobility due to their spinal cord injury registering low levels of HSP47 and no signs of inflammation-related clotting.

Tinen Iles, a computational biologist at the University of Minnesota, told Science News that the study was a “huge step forward.”

Iles, who was not involved with this research, said that the study had brought together scientists from various backgrounds, including wildlife biologists and healthcare experts and showed how animals had adapted to stop immobility-related blood clots.

This meant that researchers now have a roadmap to mimic nature’s solutions with drugs, Iles said.

Lead researcher Petzold told Science News that the study’s findings would mean that researchers could now look to potential drugs that would aim to stop HSP47 from interacting with proteins or immune cells that spark clots.

VTE is a condition characterized by the formation of blood clots (thrombi) in the veins, which can lead to serious health consequences if not promptly diagnosed and treated.

VTE can occur in different parts of the venous system, most commonly in the deep veins of the legs (known as deep vein thrombosis or DVT) or in the lungs (known as pulmonary embolism or PE).

VTE typically occurs when there is a disruption in the normal blood flow or a change in the blood’s coagulation balance, leading to the formation of clots.

Several risk factors can increase the likelihood of developing VTE, including:

The symptoms of VTE can vary depending on the location and size of the blood clot. Common symptoms of DVT include swelling, pain, warmth, and redness in the affected leg, while symptoms of PE may include sudden onset of shortness of breath, chest pain, rapid heartbeat, and coughing up blood.

VTE can be diagnosed through various imaging tests, such as ultrasound, CT scan, or ventilation-perfusion scan for PE.

Treatment for VTE typically involves anticoagulant medications to prevent the clot from growing and to reduce the risk of further clot formation.

VTE is a serious condition that requires prompt medical attention, and if you suspect you may have VTE or have risk factors for developing VTE, it’s important to consult a healthcare professional for proper evaluation, diagnosis, and treatment.

Researchers have published their results in the article ‘Immobility-associated thromboprotection is conserved across mammalian species from bear to human’ in the journal Science.