Mechanical mechanisms for thrombosis in microvessels

Area of Science:

• Biomedical Engineering
• Cardiovascular Research
• Hemodynamics

Background:

• Thrombus formation is a critical factor in vascular diseases.
• Mechanical stimuli in blood vessels are increasingly recognized as contributors to thrombosis.
• The role of vessel curvature in initiating thrombus formation requires further investigation.

Purpose of the Study:

• To test the hypothesis that mechanical stimuli in curved vessels can induce thrombus formation.
• To investigate the underlying mechanical mechanisms of thrombus induction in microvessels.
• To correlate experimental findings with computational fluid dynamics simulations.

Main Methods:

• In vivo experiments were conducted on Sprague-Dawley rats, focusing on mesentery microvessels (20-50 micrometer diameter).
• Microvessels were subjected to stretching and curving to observe thrombus formation.
• Three-dimensional computational simulations using FLUENT software modeled blood flow (Newtonian, laminar, Re~0.01) in curved and non-curved vessels with varying cross-sectional shapes.

Main Results:

• Thrombi were observed forming in 7 out of 32 stretched and curved, non-injured microvessels.
• Thrombus initiation occurred at the inner side of the curved vessels.
• Computational simulations revealed higher shear rate and shear rate gradient at the inner side of curved vessels, especially in more curved and elliptical ones.

Conclusions:

• Mechanical stimuli, specifically higher shear rate and shear rate gradient at the inner curve, are key factors initiating thrombosis in curved post-capillary venules.
• Findings are consistent with thrombus formation observed in branched venules.
• This study provides experimental and computational evidence linking vessel geometry and mechanical forces to thrombus induction.