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Updated: Oct 29, 2026

The Nijmegen Hemostasis Assay: Simultaneous Fluorogenic Measurement of Thrombin and Plasmin Generation in a Single Well
Published on: February 27, 2026
Enhanced Plasmin Generation Due to PAI-1 Deficiency Impairs Regulated Vascular Endothelial Cell Motility
Hideto Sano1, Masahiko Ito2, Tetsuro Suzuki2
1Department of Medical Physiology, Hamamatsu University School of Medicine, Hamamatsu, Japan,; Department of Physiology, Tokai University School of Medicine, Hamamatsu, Japan,.
Background:
Plasminogen activator (PA) inhibitor (PAI)-1 plays crucial roles in the plasminogen activation system and fibrinolysis. Congenital PAI-1 deficiency in humans is characterized by severe bleeding and delayed wound healing, indicating dysregulated plasmin activity. However, how PAI-1 controls pericellular plasmin generation and endothelial cell (EC) behavior remains unclear.
Objective:
To elucidate the specific effects of enhanced plasmin generation caused by PAI-1 deficiency on human ECs.
Methods:
PAI-1-deficient human ECs (PAIKO-ECs) were generated using CRISPR/Cas9 and compared with wild-type ECs. The effects of enhanced pericellular plasmin generation caused by PAI-1 deficiency on endothelial cell migration and angiogenic tube formation were evaluated, and transcriptome analyses were performed to investigate the molecular mechanism.
Results:
PAIKO-ECs showed markedly increased plasmin generation compared to wild type ECs. They exhibited increased overall uncoordinated motility with multidirectional migration trajectories and impaired directional wound closure, while cell proliferation remained unaffected. This aberrant migratory phenotype was reversed by aprotinin, recombinant PAI-1, or the lysine analog epsilon-aminocaproic acid (EACA). EACA notably reduced plasminogen accumulation on the cell surface while preserving fluid-phase plasmin generation, suggesting enhanced EC motility is driven by pericellular rather than fluid-phase plasmin activity. In tube formation assays, PAIKO-ECs displayed increased extremities and branches, which was normalized by EACA or aprotinin. Transcriptome analyses revealed differential gene expression related to fibrinolysis, angiogenesis, and endothelial-mesenchymal transition.
Conclusions:
Pericellular plasmin activity is essential for EC motility and angiogenic behavior under PAI-1-deficient conditions, highlighting the importance of spatially regulated plasmin activity in vascular remodeling.
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