Plasma fibronectin supports hemostasis and regulates thrombosis
Yiming Wang, … , John Freedman, Heyu Ni
Yiming Wang, … , John Freedman, Heyu Ni
Published September 2, 2014
Citation Information: J Clin Invest. 2014;124(10):4281-4293. https://doi.org/10.1172/JCI74630.
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Research Article Hematology

Plasma fibronectin supports hemostasis and regulates thrombosis

Abstract

Plasma fibronectin (pFn) has long been suspected to be involved in hemostasis; however, direct evidence has been lacking. Here, we demonstrated that pFn is vital to control bleeding in fibrinogen-deficient mice and in WT mice given anticoagulants. At the site of vessel injury, pFn was rapidly deposited and initiated hemostasis, even before platelet accumulation, which is considered the first wave of hemostasis. This pFn deposition was independent of fibrinogen, von Willebrand factor, β3 integrin, and platelets. Confocal and scanning electron microscopy revealed pFn integration into fibrin, which increased fibrin fiber diameter and enhanced the mechanical strength of clots, as determined by thromboelastography. Interestingly, pFn promoted platelet aggregation when linked with fibrin but inhibited this process when fibrin was absent. Therefore, pFn may gradually switch from supporting hemostasis to inhibiting thrombosis and vessel occlusion following the fibrin gradient that decreases farther from the injured endothelium. Our data indicate that pFn is a supportive factor in hemostasis, which is vital under both genetic and therapeutic conditions of coagulation deficiency. By interacting with fibrin and platelet β3 integrin, pFn plays a self-limiting regulatory role in thrombosis, suggesting pFn transfusion may be a potential therapy for bleeding disorders, particularly in association with anticoagulant therapy.

Authors

Yiming Wang, Adili Reheman, Christopher M. Spring, Jalil Kalantari, Alexandra H. Marshall, Alisa S. Wolberg, Peter L. Gross, Jeffrey I. Weitz, Margaret L. Rand, Deane F. Mosher, John Freedman, Heyu Ni

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Figure 6

Role of pFn in platelet aggregation and thrombus formation in the presence or absence of fibrin.

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Role of pFn in platelet aggregation and thrombus formation in the presen...
(A) Thrombin-induced (0.2 U/ml) FG–/– pFn–/– and FG–/– gel-filtered platelet aggregation. (B) Thrombin-induced (0.2 U/ml) or TRAP-induced (500 μM) Vwf–/– pFn–/– and Vwf–/– gel-filtered platelet aggregation. (C) Collagen-induced (20 μg/ml) Vwf–/– pFn–/– and Vwf–/– gel-filtered platelet aggregation. (D) ADP-induced (20 μM) Vwf–/– pFn–/– and Vwf–/– platelet aggregation in PRP. (E)Thrombin-induced (0.2 U/ml) pFn+/+ and pFn–/– gel-filtered platelet aggregation. All representative tracings of platelet aggregation are shown from at least 3 independent experiments. (F) Thrombus formation in a collagen-coated perfusion chamber infused with blood from FG–/– pFn–/– mice and their pFn+/+ FG–/– littermates (shear rate = 1,800 s–1). Images were taken with a confocal microscopy after infusion for 3 minutes. Grid in the image represents 10 μm. (G) Thrombus volume measured 3 minutes after infusion. n = 5 in each group. (H) Thrombus formation in FG–/– pFn–/– mice and their pFn+/+ FG–/– littermates observed in the laser-induced cremaster arterial thrombosis model. The curves represent pFn or platelet mean fluorescent intensity, and the shaded regions represent SEM. (I) The total area under the curve (AUC) was greater in FG–/– pFn–/– mice than in FG–/– mice. n = 5 in each group. Data are presented as mean ± SEM.