Pre-Clinical Model to Study Recurrent Venous Thrombosis in the Inferior Vena Cava.

BACKGROUND: Patients undergoing deep vein thrombosis (VT) have over 30% recurrence, directly increasing their risk of post-thrombotic syndrome. Current murine models of inferior vena cava (IVC) VT model host one thrombosis event. OBJECTIVE: We aimed to develop a murine model to study IVC recurrent VT in mice. MATERIALS AND METHODS: An initial VT was induced using the electrolytic IVC model (EIM) with constant blood flow. This approach takes advantage of the restored vein lumen 21 days after a single VT event in the EIM demonstrated by ultrasound. We then induced a second VT 21 days later, using either EIM or an IVC ligation model for comparison. The control groups were a sham surgery and, 21 days later, either EIM or IVC ligation. IVC wall and thrombus were harvested 2 days after the second insult and analysed for IVC and thrombus size, gene expression of fibrotic markers, histology for collagen and Western blot for citrullinated histone 3 (Cit-H3) and fibrin. RESULTS: Ultrasound confirmed the first VT and its progressive resolution with an anatomical channel allowing room for the second thrombus by day 21. As compared with a primary VT, recurrent VT has heavier walls with significant up-regulation of transforming growth factor-ß (TGF-ß), elastin, interleukin (IL)-6, matrix metallopeptidase 9 (MMP9), MMP2 and a thrombus with high citrullinated histone-3 and fibrin content. CONCLUSION: Experimental recurrent thrombi are structurally and compositionally different from the primary VT, with a greater pro-fibrotic remodelling vein wall profile. This work provides a VT recurrence IVC model that will help to improve the current understanding of the biological mechanisms and directed treatment of recurrent VT.

Clinical relevance of fibrin fiber diameter during different phases of pregnancy.

INTRODUCTION: Pregnancy-related deep vein thrombosis (DVT) is most common during the late phase of pregnancy and the first 6-weeks postpartum. Pregnancy-related DVT can have long-term complications, specifically post-thrombotic syndrome (PTS). Fibrin network ultrastructure is altered during pregnancy and post-partum. It is therefore essential to evaluate fibrin fiber diameter during and after pregnancy as this may provide insight into pregnancy-related DVT and subsequent PTS. MATERIALS AND METHODS: The fibrin network ultrastructure of females during different phases of pregnancy was compared to that of non-pregnant females to assess possible changes to the fibrin network morphology and fibrin fiber diameter using scanning electron microscopy micrographs. RESULTS: The fibrin network arrangement was more densely packed during different phases of pregnancy, corresponding to earlier findings. Fibrin diameter decreased significantly during pregnancy, with the greatest decrease occurring during the late phase of pregnancy. The fractal dimensions of fibrin micrographs increased significantly during pregnancy compared to nonpregnant females. These changes are indicative of a simultaneous hypercoagulable and hypofibrinolytic state and correspond to the increased risk of DVT and subsequent development of PTS. CONCLUSION: It is critical to identify "vulnerable" females with an inflammatory predisposition to prevent possible DVT and subsequent PTS. Modifiable risk factors like obesity and smoking should be addressed to alleviate the burden on the coagulation system. Morphological and viscoelastic techniques are crucial in assessing the coagulatory health of females during pregnancy.

Venous stasis and whole blood platelet aggregometry: a question of data reliability and patient safety.

The assessment of platelet function by multiple electrode aggregometry (MEA) (Multiplate, Roche Diagnostics GmbH) is common in laboratory hematology. As regards the ISO 15189:2012 international standard, appropriate use of laboratory equipment requires appropriate pre-examination activities (e.g., blood collection). Venous stasis can influence several blood analytes, but the tourniquet time is rarely regarded as a source of variability. Aim of the present study was to evaluate the impact of venous stasis on platelet function by MEA. A total of 6 ml of blood was collected from 20 volunteers into two 3.0 ml Hirudin vacuum tube (Roche Diagnostics GmbH), and subjected to two procedures: procedure 1 (no stasis) - collection after localization of forearm vein by subcutaneous tissue transilluminator device without tourniquet; procedure 2 (stasis) - collection after localization of vein by prior 60 s tourniquet application. Samples were processed on Multiplate, for: ADP-test (without prostaglandin E1), ADP HS-test (with prostaglandin E1), ASPI-test, COL-test, RISTO H-test (high concentration, 0.77 mg/ml), RISTO L-test (low concentration, 0.20 mg/ml), and TRAP-test. The significance of the differences between samples was assessed by Wilcoxon ranked-pairs test. Surprisingly, the results of ADP HS-test, ASPI-test, COL-test, and RISTO H-test appeared unbiased by venous stasis. RISTO L-test, ADP-test, and TRAP-test were significantly biased; the mean percent difference between stasis and no stasis were -7.2% (P = 0.040), -28.4% (P = 0.015), and 1.1% (P = 0.031), respectively. In conclusion, the tourniquet should be avoided when assessing platelet function by MEA.

Genetic polymorphisms of vein wall remodeling in chronic venous disease: a narrative and systematic review.

Chronic venous disease encompasses a spectrum of disorders caused by an abnormal venous system. They include chronic venous insufficiency, varicose veins, lipodermatosclerosis, postthrombotic syndrome, and venous ulceration. Some evidence suggests a genetic predisposition to chronic venous disease from gene polymorphisms associated mainly with vein wall remodeling. The literature exploring these polymorphisms has not been reviewed and compiled thus far. In this narrative and systematic review, we present the current evidence available on the role of polymorphisms in genes involved in vein wall remodeling and other pathways as contributors to chronic venous disease. We searched the EMBASE, Medline, and PubMed databases from inception to 2013 for basic science or clinical studies relating to genetic associations in chronic venous disease and obtained 38 relevant studies for this review. Important candidate genes/proteins include the matrix metalloproteinases (extracellular matrix degradation), vascular endothelial growth factors (angiogenesis and vessel wall integrity), FOXC2 (vascular development), hemochromatosis (involved in venous ulceration and iron absorption), and various types of collagen (contributors to vein wall strength). The data on associations between these genes/proteins and the postthrombotic syndrome are limited and additional studies are required. These associations might have future prognostic and therapeutic implications.

Deletion of cysteine-cysteine receptor 7 promotes fibrotic injury in experimental post-thrombotic vein wall remodeling.

OBJECTIVE: Deep vein thrombosis (VT) can result in vein wall injury, which clinically manifests as post-thrombotic syndrome. Postinjury fibrosis may be modulated in part through cellular cysteine-cysteine receptor 7 (CCR7)-mediated events. We tested the hypothesis that late vein wall fibrotic remodeling is dependent on CCR7. APPROACH AND RESULTS: CCR7(-/-) and C57BL/6 wild-type mice had inferior vena cava VT induced by nonstasis or stasis mechanisms. In both models, VT size was largest at day 1 and trended down by day 21, and CCR7(+) cells peaked at day 8 in wild-type mice. No significant differences in VT resolution were found in CCR7(-/-) as compared with wild type in either model. In the nonstasis VT model, vein wall changes consistent with fibrotic injury were evidenced by significant increases in collagen I, III, matrix metalloproteinase 2, and transforming growth factor-ß gene expression, increases in α-smooth muscle actin and fibroblast specific protein-1 antigen, and total collagen at 8 days. Correspondingly, SM22α and fibroblast specific protein-1, but not DDR2(+) cells, were increased at 8 days. Early wild-type thrombus exposure inhibited profibrotic gene expression in CCR7(-/-) in ex vivo vein wall culture. Bone marrow chimera experiments further showed that circulating CCR7(+) leukocytes partially rescued midterm profibrotic changes in CCR7(-/-) mice. In human histological sections of chronic thrombosed femoral veins, CCR7(+) cells were present in the fibrotic areas. CONCLUSIONS: Post-thrombotic vein wall remodeling is impaired in CCR7(-/-) mice, with a profibrotic phenotype, is dependent on the thrombotic mechanism, and is mediated by circulating CCR7(+) cells. Unlike other postinjury fibrotic responses, CCR7(+) signaling may be important for positive vein wall remodeling after VT.

[Early surgery for iliac-femoral post-thrombotic syndrome and related experimental study].

OBJECTIVES: To confirm the occurrence time of iliac-femoral post-thrombotic syndrome (IFPTS) with the experimental analysis of fibrinolytic activation and vessel wall remodeling after iliofemoral vein thrombosis (IFVT). To explore the optimal timing of surgery for IFPTS with comparative study of surgical effect after early and late treatment. METHODS: IFVT was performed on 20 SD rats. The plasminogen activation [tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA)] and vascular remodeling (positive rates of internal elastic membrane, vascular perimeter and vessel wall stiffness index) were detected by immunohistochemistry and Weigert Van Gieson staining respectively. Fifty-one IFPTS patients with Palma-Dale treatment from January 1990 to December 2005 were divided into early surgical group (1 to 2 months after IFVT) and later surgical group (> 2 months after IFVT), including 20 patients and 31 patients respectively. Treatment effects were evaluated by venous clinical severity score (VCSS). RESULTS: The positive rate of internal elastic membrane decreased significantly at the 4th, 8th and 12th week (P < 0.01), while the vessel wall stiffness index increased at the same time (P < 0.01). The vascular perimeter elevated obviously at 12th week (P < 0.05). Symptoms of early treatment group improved significantly after surgery (3.4 ± 0.9 vs. 5.2 ± 1.2, P < 0.05). Whereas the late treatment group had no significant changes of symptoms (6.8 ± 1.7 vs. 7.6 ± 3.0, P > 0.05). CONCLUSIONS: The present findings suggest that IFPTS occurs around first month after IFVT. Acceptable surgery timing for IFPTS exists at 1 to 2 months post-IFVT.