Role of surface-bound FXIII on fibrin gelation and deposition

Physiological processes like blood clotting, wound healing, and tissue regeneration rely significantly on the strength and stability of fibrin networks, with the crosslinking of fibrin fibers by transglutaminase enzyme factor XIII (FXIII-A) being a key contributor [1]. Our prior research demonstrated that FXIII-A exposed on activated platelets can enhance the mechanical properties of fibrin clots, compensating for the absence of plasma FXIII-A [2]. This study explores the hypothesis that fibrin crosslinking by surface-bound FXIII-A results in intense fibrin densification, potentially increasing local network stiffness and improving force transmission during platelet and cell contraction [3].
To maintain constant FXIII-A site density and eliminate feedback regulation, a cell-free system utilized FXIII-A-coated microspheres mixed with FXIII-free plasma and AF594-conjugated fibrinogen. Fibrin gelation kinetics were visualized using fluorescence microscopy and quantified with ImageJ and Matlab, with statistical analysis performed using Student’s t-test.
Fibrin deposition on FXIII-A-coated beads decreased exponentially from the bead surface. FXIII-A-coated surfaces exhibited significantly higher fibrin deposition than anti-fibrin E antibody-coated surfaces, following a logistic profile indicating cooperative crosslinking effects. The addition of FXIII to FXIII-free plasma reduced fibrin deposition on FXIII-coated surfaces, suggesting competitive inhibition. These findings shed light on the intricate role of platelet FXIII-A in hemostasis, emphasizing its potential to locally increase fibrin network density.
References
[1] Muszbek et al., Physiol Rev 91: 931–972, 2011
[2] Nair et al., Br J Haematol 178(1):119-129, 2017
[3] Han et al., PNAS, 115(16): 4075-4080

Acknowledgments