Deficiency in thrombin-activatable fibrinolysis inhibitor (TAFI) protected mice from ferric chloride-induced vena cava thrombosis

Abstract

Thrombin-activatable fibrinolysis inhibitor (TAFI) is a plasma carboxypeptidase that renders a fibrin-containing thrombus less sensitive to lysis. Since the role of TAFI in thrombus formation is still controversial in mice, our present study was designed to evaluate mice deficient in TAFI (TAFI(-/-)) on FeCl(3)-induced vena cava and carotid artery thrombosis. Parallel studies were carried out in wild-type mice using a potato carboxypeptidase inhibitor (PCI), a selective inhibitor of activated TAFI (TAFIa). Significant reduction in thrombus formation was observed in TAFI(-/-) mice (n = 8, P < 0.05 compared to wild-type littermates) but not in heterozygous (TAFI(+/-)) mice in 3.5% FeCl(3)-induced vena cava thrombosis. A similar effect was observed following treatment with 5 mg/kg bolus plus 5 mg/kg/h PCI in the same venous thrombosis model in C57BL/6 mice (n = 8, P < 0.01 compared to vehicle). No compositional difference was observed for the venous thrombi in TAFI(-/-) and wild-type littermates with or without PCI treatment using histological assessment. In contrast, neither TAFI deficiency nor treatment with PCI showed antithrombotic efficacy in the 3.5% FeCl(3)-induced carotid artery thrombosis model. In a tail transection bleeding time model, both TAFI deficiency and PCI treatment increased bleeding time up to 4.5 and 3.5 times, respectively, over controls (P < 0.05, n = 8). Similar ex vivo fibrinolytic activities were demonstrated for both TAFI deficiency and PCI treatment as enhanced lysis of thrombin-induced plasma clots and lysis of whole blood clot in a thrombelastograph. These data provide direct evidence for the role of TAFIa in vena cava thrombosis without the addition of exogenous thrombolytic in mice. The strong ex vivo fibrinolytic activity of TAFI deficiency or TAFIa inhibition by PCI provides a biomarker of TAFIa inhibition that tracks in vivo antithrombotic efficacy.

Choosing a mouse model of venous thrombosis: a consensus assessment of utility and application

“…The St. Thomas stenosis model has been subjected to several surgical modifications that are all broadly recognized under the stenosis model. Modifications avoid the endothelial damage step, and further vary in their [17,46] treatment of side branches as well as the chosen spacer. One variation leaves all branches open and uses a 0.36 mm wire spacer [4], while other variations interrupt side branches and use either a 30-gauge needle spacer [3,[11][12][13][14], or a 0.26 mm wire spacer [15].…”

Murine Models of Vascular Thrombosis

“…26 Schlacterman et al found 15% ferric chloride solution to be effective for determining effects of the factor V Leiden mutation on a hemophilic mouse strain of mixed C57BL6/J-129 genetic background. 27 The ferric chloride model has also been applied to study thrombosis in other mouse blood vessels including the inferior vena cava 28,29 and the microvasculature. 17 …”

Incorporation of albumin fusion proteins into fibrin clots in vitro and in vivo: comparison of different fusion motifs recognized by factor XIIIa

“…Specific activities of labelling exceeded 1 × 10 9 cpm/mg. Radioiodinated proteins were then tested in the mouse ferric chloride vena cava thrombosis model, modified from [29,30]. CD-1 mice were anaesthetized using gaseous anaesthesia (3% isofluorane) at all times during this procedure, and a heating pad was employed to ensure maintenance of normal body temperature.…”