“Don’t poke the bear,” they said. But that is exactly what a team of scientists has been doing, to discover the secrets of blood clotting.
Hibernating bears, paralyzed humans, and pigs kept in small enclosures avoid dangerous blood clots, despite being immobile for extremely long periods.
Research from the University of Reading, with partners in Denmark, Germany, Norway and Sweden, shows that reducing a key protein prevents blood clots from forming in all three mammalian species when they are still sitting still for days, weeks, months or even years. at the same time The study is published today (April 13, 2023), in Science.
If you’ve ever taken a long-haul flight, you may have taken a tip to prevent a dangerous blood clot (deep vein thrombosis) from forming in one or both legs, while sitting for several hours, dreaming of your destination. . He may have set a reminder to get up and walk around, and he wore compression stockings to keep blood from pooling in his legs.
Most people will not experience a clot if they take care of themselves on a flight, but there is a serious risk for some people who are predisposed to blood clots due to genetic factors.
The discovery that a protein known as Hsp47 is dramatically reduced, 55-fold, when someone is immobilized for a period much longer than a flight, could lead to new drugs to help those who have inherited blood-clotting disorders that put you at risk of lung disease. embolism, myocardial infarction and cerebrovascular accident.
Professor Jon Gibbins led the work at the University of Reading. He said: “It seems counterintuitive that people who have severe paralysis do not appear to be at increased risk of blood clots. This tells us that something interesting is happening. And it turns out that lowering Hsp47 levels plays a key role in preventing clots, not only in humans, but also in other mammals, including bears and pigs.
“When we see something like this in multiple species, that reinforces its importance. Having Hsp47 must have been an evolutionary advantage.”
Hsp47 is released by platelets, the sticky blood cells that trigger blood clotting. Clotting is usually an important response to injury, to prevent blood loss, and Hsp47 is one of the necessary ingredients to allow platelets to do their job. By examining the role of Hsp47 in clotting function, the team discovered that when released into the blood of bears, mice and humans, it promotes conditions that can lead to deep vein thrombosis.
Professor Gibbins said: “We’re not entirely sure how, but there seems to be something in the movement that is keeping Hsp47 at an appropriate level. It could be that the mechanical forces involved in movement have an impact on gene expression, drastically increasing the amount of Hsp47 circulating in the blood.”
The team took blood samples from bears in winter, while they were hibernating, and in summer, while they were awake and moving. They also compared people who were immobilized to those who can move and walk. And finally, pigs kept in small pens were compared with others that roamed freely in the stalls. In all three cases, the proteomics experiments showed that the absence of movement was associated with having much less Hsp47.
Professor Gibbins said: “Now that we know that Hsp47 is so important, we can start looking for new or existing drugs that can inhibit the function of this protein in blood clotting and protect mobile people who are prone to clots.” .