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Updated: May 5, 2026

Experimental and Imaging Techniques for Examining Fibrin Clot Structures in Normal and Diseased States
Published on: April 1, 2015
The effect of blood coagulation factor XIII on fibrin clot structure and fibrinolysis
E L Hethershaw1, A L Cilia La Corte, C Duval
1Division of Cardiovascular and Diabetes Research, Multidisciplinary Cardiovascular Research Centre, Faculty of Medicine and Health, Leeds Institute for Genetics Health and Therapeutics, University of Leeds, Leeds, UK.
Background:
Factor XIII is a 320 kDa tetramer, comprising two enzymatic A-subunits and two carrier B-subunits (FXIII A₂ B₂). Activated FXIII (FXIIIa) catalyses the formation of ε-(γ-glutamyl)lysyl covalent bonds between γ-γ, γ-α and α-α chains of adjacent fibrin molecules and also cross-links the major plasmin inhibitor, α2-antiplasmin, to fibrin.
Objectives:
We investigated the role of FXIII cross-linking of fibrin directly in clot morphology and its functional effect on clot formation and lysis, in the absence of α2-antiplasmin.
Results And Conclusions:
Our data show that the presence of FXIII during clot formation results in fibrin clots that have a significant 2.1-fold reduction in pore size, as determined by the Darcy constant, Ks, and formed thinner fibers (74.7 ± 1.5 nm) and higher density of fibers compared with those without FXIII (86.0 ± 1.7 nm, P < 0.001), as determined by scanning electron microscopy. Additionally, fibrinolysis showed a significant increase in the time to lysis for clots formed in the presence of FXIII in both static and flow systems. These data demonstrate that independent of α2-antiplasmin, FXIII activity plays a role in increasing the stability of the fibrin clot by altering its structure and increasing the resistance to fibrinolysis.
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