Local preconditioning by thermal stress accelerates microvascular thrombus formation

Area of Science:

• Vascular Biology
• Thrombosis Research
• Stress Physiology

Background:

• Heme oxygenase 1 (HO-1) is known to inhibit microvascular thrombus formation.
• Stress conditioning can induce HO-1, thrombomodulin, and thrombospondin 1.

Purpose of the Study:

• To investigate the effect of local hyperthermic and hypothermic stress conditioning on microvascular thrombus formation.
• To determine if stress conditioning, despite inducing anticoagulant factors, can prevent thrombosis.

Main Methods:

• Sprague-Dawley rats underwent local hindlimb heating (42.5°C) or cooling (4°C) for 30 minutes.
• Thrombosis was induced photochemically in arterioles and venules of preconditioned tissues.
• Immunohistochemistry and intravital fluorescence microscopy were used to analyze thrombus formation kinetics and protein expression.

Main Results:

• Stress conditioning significantly induced HO-1, thrombomodulin, thrombospondin 1, and von Willebrand factor.
• Contrary to expectations, stress conditioning did not show an antithrombotic effect.
• A significant acceleration of thrombus formation was observed in both arterioles and venules.

Conclusions:

• Local hyperthermic and hypothermic stress conditioning enhances endogenous thrombogenicity.
• Upregulation of prothrombotic von Willebrand factor likely contributes to accelerated thrombosis.
• Stress preconditioning is not a suitable strategy for preventing microvascular thrombus formation.