The effect of blood coagulation factor XIII on fibrin clot structure and fibrinolysis

J Thromb Haemost. 2014 Feb;12(2):197-205. doi: 10.1111/jth.12455.


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.

Keywords: blood coagulation; electron microscopy; factor XIII; fibrin; fibrinolysis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromatography, Gel
  • Factor XIII / physiology*
  • Fibrin / chemistry
  • Fibrin / physiology*
  • Fibrinolysis
  • Humans
  • Microscopy, Confocal


  • Fibrin
  • Factor XIII