The Role Of Hemostatic Clots In Wound Healing: Effects On Endothelial Cell Response

Abstract

Effective wound healing is essential for restoring tissue integrity and function following vascular injury. This process involves tightly coordinated interactions between platelets, fibrin, and endothelial cells (ECs), yet the role of fibrin clot structure in regulating EC behavior during wound repair remains incompletely understood. Following endothelial injury, platelets adhesion and activation initiate primary hemostasis, while the coagulation cascade generates thrombin leading to formation of fibrin and the development of a stabilizing clot. Beyond its structural role, fibrin also serves as a dynamic matrix that can influence cellular behavior, while its degradation through fibrinolysis is critical for restoring tissue function. The objective of this work is to investigate how plasma clot composition and structure regulate endothelial cell dynamics during wound healing. An in vitro wound healing model incorporating plasma-derived fibrin clots was developed to examine the interplay between clot formation, fibrinolysis, and EC migration. Live-cell confocal imaging revealed that dense platelet-poor plasma (PPP) clots strongly inhibit wound closure by restricting endothelial cell migration. In contrast, modulation of fibrin architecture and the incorporation of platelets into platelet-rich plasma (PRP) clots enabled endothelial cell infiltration and supported wound resolution, albeit at reduced rates compared to clot-free conditions. Furthermore, fibrinolysis induced by tissue plasminogen activator (tPA) restored wound healing in previously inhibited PPP conditions. Quantitative analysis demonstrated significant morphological differences in endothelial cells under clot versus no-clot conditions, suggesting alterations in migratory and angiogenic behavior. Structural characterization of fibrin networks indicated that platelet-driven remodeling and variations in fiber organization may underlie the observed differences in wound healing outcomes. Overall, these findings demonstrate that fibrin clot architecture and platelet activity play a critical role in regulating endothelial cell behavior during wound healing. This work provides mechanistic insight into EC-fibrin interactions and highlights the importance of clot microstructure in determining whether the hemostatic clot functions as a barrier or a permissive scaffold for vascular repair.