Analysis of Thrombus Composition and Architecture in a High-Shear vs Low-Shear Stress Environment
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Date
2025-05
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Publisher
The Ohio State University
Abstract
Introduction
Thrombotic diseases—including acute ischemic stroke (AIS) and venous thromboembolism (VTE)—are major global health burdens with current therapies limited by narrow time windows, bleeding risks, or infrastructure barriers. While arterial thrombi are often labeled “white clots” rich in platelets and venous thrombi as “red clots” rich in RBCs and fibrin, this dichotomy lacks thorough validation in human tissue. Understanding thrombus composition and architecture under different shear stress conditions may uncover novel and translatable therapeutic targets, especially for patients ineligible for standard thrombolytics.
Methods
Thrombi were collected from AIS and VTE patients under IRB protocol and processed for immunofluorescent staining. Markers for von Willebrand Factor (VWF), fibrin, CD42b (platelets), glycophorin A (RBCs), PAI-1, and NETs markers (Cit-H3, MPO, NE) were quantified by percent positive area using ImageJ segmentation. Morphology was classified as peripheral, clustering, diffuse, or mixed. A two-tailed unpaired T-test compared percent area, and Z-tests assessed morphological distribution differences between arterial (n=74) and venous (n=31) thrombi.
Results
RBCs had significantly greater percent area in venous thrombi (p=0.0039), while fibrin content was paradoxically lower in venous thrombi (p=0.0128). No significant differences were observed for VWF, platelets, PAI-1, or NETs markers. Morphologically, venous thrombi demonstrated decreased clustering and increased mixed morphologies across nearly all markers. NETs markers were predominantly diffuse in both thrombus types. VWF and fibrin exhibited substantial peripheral localization. Despite expectations, VWF levels were not significantly lower in venous thrombi, suggesting that shear stress alone does not dictate its distribution.
Conclusion
These results challenge the conventional “white vs red clot” model by revealing that fibrin is more abundant in arterial thrombi and that platelet content is not significantly reduced in venous thrombi. Elevated PAI-1 and a shell-like fibrin structure suggest thrombolytic resistance, while VWF and NETs may prove to be efficacious therapeutic targets due to their widespread presence in both AIS and VTE. This work underscores the need to revise simplistic thrombus classifications and supports targeted therapeutic innovation.
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Keywords
Thrombosis, Immunohistochemistry, Thrombolytic Therapy, Stroke, Venous Thromboembolism