Monday, April 17, 2023

Hibernating Bears Provide Clue to Preventing Serious Clots in Humans

Good news! What brown bears hibernate for six months!

"... researchers found that when bears enter their sleepy winter state, they tamp down on the production of heat-shock protein 47 (HSP47), which typically sits on the surface of platelets and helps them bind to collagen. This phenomenon isn’t unique to bears—humans and pigs also temper HSP47 production in times of immobility, the team discovered. ..."

From the perspective abstract:
"Deep vein thrombosis (DVT) is a common feature of short-term immobilization, which occurs, for example, for patients with acute paralysis. However, in chronic immobilization—e.g., owing to spinal cord injury (SCI)—the incidence of DVT equals that in the general population. The mechanisms that protect against DVT during chronic immobilization in SCI patients are unknown. ....  report an analysis of the thromboinflammatory machinery in hibernating brown bears (Ursus arctos), which rarely suffer from DVT despite 6 months of immobilization during hibernation. They found that platelets from hibernating bears exhibit an antithrombotic signature characterized by decreased expression of heat shock protein 47 (HSP47) and overall reduced biomarkers of thromboinflammation compared with those of active brown bears. Further, this signature is conserved across different animal species, including mice, pigs, and humans, suggesting that this could be a therapeutic target to reduce DVT in immobilized patients."

From the abstract:
"Venous thromboembolism (VTE) comprising deep venous thrombosis and pulmonary embolism is a major cause of morbidity and mortality. Short-term immobility-related conditions are a major risk factor for the development of VTE. Paradoxically, long-term immobilized free-ranging hibernating brown bears and paralyzed spinal cord injury (SCI) patients are protected from VTE. We aimed to identify mechanisms of immobility-associated VTE protection in a cross-species approach. Mass spectrometry–based proteomics revealed an antithrombotic signature in platelets of hibernating brown bears with heat shock protein 47 (HSP47) as the most substantially reduced protein. HSP47 down-regulation or ablation attenuated immune cell activation and neutrophil extracellular trap formation, contributing to thromboprotection in bears, SCI patients, and mice. This cross-species conserved platelet signature may give rise to antithrombotic therapeutics and prognostic markers beyond immobility-associated VTE."

Hibernating Bears Provide Clue to Preventing Serious Clots in Humans | The Scientist Magazine® Low levels of the clotting factor HSP47 protect the sleeping giants from blood clots, and the same may be possible for humans and other mammals.

Sleep like a bear (perspective, no public access) Reduced expression of a platelet protein protects against thrombosis during chronic immobilization


Outdoor research




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