Abstract Number: OC 02.1
Meeting: ISTH 2020 Congress
Background: FXIIIa crosslinks fibrin α- and γ-chains, increasing resistance to mechanical strain. The role of thrombus mechanical properties in thromboembolism in-vivo is poorly understood. In addition, current thromboembolism models are limited as they are based on systemic clotting or injection of exogenous thrombi.
Aims: To develop a genetically-modified mouse, with reduced clot elasticity due to mutations in the fibrin γ-γ crosslinking sites, and to investigate the role of clot elasticity in thromboembolism using newly developed protocols.
Methods: FGG3X mice were generated by mutating the conserved fibrinogen γ-chain crosslinking residues (γQ423N/Q424N/K431R). Clot formation was analysed ex-vivo by ROTEM and in-vivo by intravital microscopy using a FeCl3 femoral vein injury model. Additionally, pulmonary embolism was investigated live by Xtreme optical imaging, and after one hour by light-sheet microscopy, following FeCl3 injury to the inferior vena cava of mice injected with AlexaFluor647-fibrinogen.
Results: FGG3X mice were phenotypically (growth, haematological parameters) similar to WT (C57BL/6), but were unable to form γ-γ crosslinks. ROTEM clotting and lysis times were similar, however maximum clot firmness was significantly lower in FGG3X mice compared to WT, showing a reduction in clot elastic modulus. Intravital microscopy showed FGG3X mice exhibited significantly increased breakdown events during thrombus formation, compared to WT. Furthermore, Xtreme imaging showed that embolisation to the lungs was significantly higher in FGG3X mice compared to WT, at 0.5, 1, 2, 4, 24hrs post-injury of the vena cava. Light-sheet microscopy of the lungs 1hr post-injury showed a significant increase in emboli count and volume for FGG3X mice, compared to WT.
Conclusions: Our data show that γ-γ crosslinking plays a key role in clot stability during thrombosis in-vivo, and protects against pulmonary embolism. This points to important mechanistic targets for the prevention of thromboembolism through selective modulation of fibrin crosslinking to reduce thrombus burden, while maintaining clot stability.
To cite this abstract in AMA style:Duval C, Baranauskas A, Ali M, Raslan Z, Baker SR, McPherson HR, Bailey MA, Cubbon RM, Ajjan RA, Philippou H, Naseem KK, Ridger VC, Ariëns RAS. Fibrin γ-chain Crosslinking Plays an Important Role in Preventing Thrombus Breakdown and Embolisation in-vivo [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/fibrin-%ce%b3-chain-crosslinking-plays-an-important-role-in-preventing-thrombus-breakdown-and-embolisation-in-vivo/. Accessed September 16, 2021.
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