Scientists at Ludwig-Maximilians-Universität Munich have discovered that thanks to the reduced activity of heat shock protein 47, bears can hibernate without risk of developing thrombosis. The results were published in the journal Science.
Prolonged inactivity can put people at risk of dangerous blood clots in their legs that can travel to the lungs or brain and cause pulmonary embolism or stroke. At the same time, bears can hibernate for months and do not suffer from blood clots.
In their new study, the researchers found that hibernating bears had 55-fold reduced activity levels of a particular protein called heat shock protein 47 (HSP47) compared to when they were active.
More importantly, the researchers discovered that this phenomenon also occurs in other species, including humans. HSP47 activity is reduced, especially in people who are paralyzed due to spinal cord injury. This explains why paralyzed people are no more likely to develop blood clots than mobile people. However, temporary inactivity — recovering from an injury or surgery or taking a long flight — can contribute to blood clots in many people.
Various medications, including aspirin, are now used to prevent blood clots in people at risk. But it has side effects, including an increased risk of bleeding. HSP47 could be a target for safer anti-clot drugs.