Regular Article Circulating tissue factor positive microparticles in patients with acute recurrent deep venous thrombosis Runyi Ye a, 1 , Caisheng Ye a, 1 , Yongbo Huang b , Longshan Liu c , Shenming Wang a, ⁎ a Department of Vascular Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China b Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China c Department of Surgical Laboratory, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China abstract article info Article history: Received 15 July 2011 Received in revised form 24 September 2011 Accepted 17 October 2011 Available online 17 November 2011 Keywords: Deep venous thrombosis Recurrence Microparticles Tissue factor Introduction: Circulating tissue factor positive microparticles (MPTF) were reported in a wide range of dis- eases with thrombotic tendency. Though D-dimer assay had a high negative predictive value for deep venous thrombosis (DVT) recurrence, there are currently no reliable positive predictors for recurrent DVT. We there- fore quantified MPTF in patients with acute recurrent DVT to determine whether MPTF levels could be used to predict recurrent DVT. Materials and Methods: Microparticles (MPs) were isolated from plasma of initial DVT patients (n = 25), recurrent DVT patients (n = 25) and sex- and age-matched healthy individuals (n = 25), stained with annexin V, cell- specific monoclonal antibodies (MoAbs) and a MoAb directed against tissue factor (TF), and analyzed by flow cytometry. We also determined the plasma procoagulant activity with a Human TF Chromogenic Activity Assay Kit. Results: We found total MPTF to be elevated in recurrent DVT patients versus normal individuals (P =0.001). The number of monocyte-derived MPTF in both initial and recurrent DVT was higher than in normal individuals (P b 0.01, respectively). The platelet and endothelial cell derived MPTF in recurrent DVT were significantly in- creased relative to other MPTF (P b 0.05), although there was no difference between initial DVT patients and nor- mal individuals. We demonstrated elevated procoagulant activity of platelet-free plasma in DVT patients relative to normal individuals, and a positive correlation with MPTF. Conclusions: The elevated MPTF could be a potentially predictor for DVT recurrence. Further studies are needed to validate its sensitivity and specificity. © 2011 Elsevier Ltd. All rights reserved. Introduction Deep venous thrombosis (DVT) of the lower limbs is a common disease with serious complications, including pulmonary thrombo- embolism and post-thrombotic syndrome (PTS). After stopping anti- coagulant treatment, individuals who have had a first episode of DVT are at an increased risk of new events. In patients who received standard anticoagulation for 3 to 6 months after an incident event, the cumulative rate of recurrence is 21% to 23% at 4 to 5 years, and as high as 40% at 10 years after diagnosis [1,2]. About 5% of recurrent episodes are fatal, recurrent DVT markedly increases the risk of PTS and recurrent pulmonary embolism [3]. Although oral anticoagulant treatment is highly effective, its use is hampered by its drawbacks such as frequent laboratory monitoring, dose adjustment and an in- creased risk of major hemorrhage. Consequently, identification of risk factors for recurrent DVT is important and could help to decide whether to stop or to continue anticoagulant therapy. Risk factors as- sociated with increased recurrence were idiopathic or unprovoked DVT, proximal DVT, cancer, male gender, oral contraceptive use, and shorter duration of anticoagulation [4]. The objective test of D-dimer assay after vitamin K antagonist dis- continuation had a high negative predictive value for DVT recurrence and could be used to guide the optimal duration of anticoagulation for patients with a first unprovoked DVT [5]. However, there are currently no reliable positive predictors for recurrent DVT. The discovery of vari- ous tissue factor positive microparticles (MPTF) and their procoagulant activity, makes them a potentially predictor alternative. Giesen and colleagues [6] first demonstrated the existence of func- tionally intact microparticles (MPs) containing tissue factor in the blood of normal individuals. Tissue factor (TF) is an important initiator of the extrinsic pathway of blood coagulation, and can be detected in the vessel wall and the blood [7]. The majority of circulating TF is present in the form of MPs, which are small membrane fragments released from activated or apoptotic vascular cells [8]. MPs are highly heterogeneous in Thrombosis Research 130 (2012) 253–258 Abbreviations: DVT, Deep venous thrombosis; PTS, post-thrombotic syndrome; MPs, microparticles; MPTF, tissue factor positive microparticles; TF, tissue factor; PFP, platelet-free plasma; MoAbs, monoclonal antibodies. ⁎ Corresponding author at: Department of Vascular Surgery, The First Affiliated Hospital of Sun Yat-sen University, 58 Zhongshan Road II, Guangzhou, Guangdong 510080, China. Fax: +86 20 87335856. E-mail address: shenmingwang@vip.sohu.com (S. Wang). 1 These two authors contributed equally to this paper. 0049-3848/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.thromres.2011.10.014 Contents lists available at SciVerse ScienceDirect Thrombosis Research journal homepage: www.elsevier.com/locate/thromres