Vascular endothelial growth factor and basic fibroblast growth factor are found in resolving venous thrombi

Monocyte/macrophage-mediated venous thrombus resolution

Venous thromboembolism (VTE) poses a notable risk of morbidity and mortality. The natural resolution of the venous thrombus might be a potential alternative treatment strategy for VTE. Monocytes/macrophages merge as pivotal cell types in the gradual resolution of the thrombus. In this review, the vital role of macrophages in inducing inflammatory response, augmenting neovascularization, and facilitating the degradation of fibrin and collagen during thrombus resolution was described. The two phenotypes of macrophages involved in thrombus resolution and their dual functions were discussed. Macrophages expressing various factors, including cytokines and their receptors, adhesion molecules, chemokine receptors, vascular endothelial growth factor receptors, profibrinolytic- or antifibrinolytic-related enzymes, and other elements, are explored for their potential to promote or attenuate thrombus resolution. Furthermore, this review provides a comprehensive summary of new and promising therapeutic candidate drugs associated with monocytes/macrophages that have been demonstrated to promote or impair thrombus resolution. However, further clinical trials are essential to validate their efficacy in VTE therapy.

Ononin: A comprehensive review of anticancer potential of natural isoflavone glycoside

Cancer is one of the major causes of death worldwide, with more than 10 million deaths annually. Despite tremendous advances in the health sciences, cancer continues to be a substantial global contributor to mortality. The current treatment methods demand a paradigm shift that not only improves therapeutic efficacy but also minimizes the side effects of conventional medications. Recently, an increased interest in the potential of natural bioactive compounds in the treatment of several types of cancer has been observed. Ononin, also referred to as formononetin-7-O-β-d-glucoside, is a natural isoflavone glycoside, derived from the roots, stems, and rhizomes of various plants. It exhibits a variety of pharmacological effects, including Antiangiogenic, anti-inflammatory, antiproliferative, proapoptotic, and antimetastatic activities. The current review presents a thorough overview of sources, chemistry, pharmacokinetics, and the role of ononin in affecting various mechanisms involved in cancer. The review also discusses potential synergistic interactions with other compounds and therapies. The combined synergistic effect of ononin with other compounds increased the efficacy of treatment methods. Finally, the safety studies, comprising both in vitro and in vivo assessments of ononin's anticancer activities, are described.

Map of thrombogenesis in viral infections and viral-driven tumours

Viruses are pathogenic agents responsible for approximately 10% of all human cancers and significantly contribute to the global cancer burden. Until now, eight viruses have been associated with the development of a broad range of malignancies, including solid and haematological tumours. Besides triggering and promoting oncogenesis, viral infections often go hand-in-hand with haemostatic changes, representing a potential risk factor for venous thromboembolism (VTE). Conversely, VTE is a cardiovascular condition that is particularly common among oncological patients, with a detrimental impact on patient prognosis. Despite an association between viral infections and coagulopathies, it is unclear whether viral-driven tumours have a different incidence and prognosis pattern of thromboembolism compared to non-viral-induced tumours. Thus, this review aims to analyse the existing evidence concerning the association of viruses and viral tumours with the occurrence of VTE. Except for hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infection, which are associated with a high risk of VTE, little evidence exists concerning the thrombogenic potential associated with oncoviruses. As for tumours that can be induced by oncoviruses, four levels of VTE risk are observed, with hepatocellular carcinoma (HCC) and gastric carcinoma (GC) associated with the highest risk and nasopharyngeal carcinoma (NPC) associated with the lowest risk. Unfortunately, the incidence of cancer-related VTE according to tumour aetiology is unknown. Given the negative impact of VTE in oncological patients, research is required to better understand the mechanisms underlying blood hypercoagulability in viral-driven tumours to improve VTE management and prognosis assessment in patients diagnosed with these tumours.

Impact of repeated intravenous infusions of umbilical cord-derived versus bone marrow-derived mesenchymal stem cells on angiogenesis in a pregnant experimentally induced deep venous thrombosis rat model

Deep venous thrombosis (DVT) therapy during pregnancy warrants special consideration for the woman and the fetus. This study aimed to evaluate the impact of umbilical cord-derived mesenchymal stem cells (UC-MSCs) and bone marrow-derived mesenchymal stem cells (BM-MSCs) in terms of pro-angiogenic capacity and amelioration of pregnancy outcomes. The pregnant DVT rat model was successfully established by the "stenosis" method. Three consecutive injections of both UC-MSCs and BM-MSCs improved angiogenesis and ameliorated the embryo absorption rate in pregnant SD rats with DVT, in which UC-MSCs promoted angiogenesis more significantly. Furthermore, the levels of serum vascular endothelial growth factor-A (VEGF-A) and epidermal growth factor (EGF) were significantly higher in the UC-MSC group compared to those of the BM-MSC group. Thereafter, differentially expressed genes (DEGs) in thrombosed inferior vena cava tissues in the UC-MSC and BM-MSC groups were identified using transcriptome sequencing and further assessed by RT-qPCR and western blotting. The bioinformatics analysis indicated that the enriched DEG terms occurred in the cytokine activity, and the DEG pathways were significantly enriched in the cytokine-cytokine receptor interaction. In addition, both the mRNA and protein levels of angiogenic genes and their receptors, including VEGF-A, VEGF receptor-1, EGF, and EGF receptor, were significantly higher in the UC-MSC group. In conclusion, the BM-MSCs and UC-MSCs both significantly stimulate angiogenesis and ameliorate the embryo absorption rate in pregnant SD rats with DVT, but the difference in cytokine secretion causes UC-MSCs to have more potent angiogenic effects than BM-MSCs.

Ferulic Acid: A Natural Phenol That Inhibits Neoplastic Events through Modulation of Oncogenic Signaling

Despite the immense therapeutic advances in the field of health sciences, cancer is still to be found among the global leading causes of morbidity and mortality. Ethnomedicinally, natural bioactive compounds isolated from various plant sources have been used for the treatment of several cancer types and have gained notable attention. Ferulic acid, a natural compound derived from various seeds, nuts, leaves, and fruits, exhibits a variety of pharmacological effects in cancer, including its proapoptotic, cell-cycle-arresting, anti-metastatic, and anti-inflammatory activities. This review study presents a thorough overview of the molecular targets and cellular signaling pathways modulated by ferulic acid in diverse malignancies, showing high potential for this phenolic acid to be developed as a candidate agent for novel anticancer therapeutics. In addition, current investigations to develop promising synergistic formulations are also discussed.

The combination of EGCG with warfarin reduces deep vein thrombosis in rabbits through modulating HIF-1α and VEGF via the PI3K/AKT and ERK1/2 signaling pathways

Deep venous thrombosis (DVT) poses a major challenge to public health worldwide. Endothelial cell injury evokes inflammatory and oxidative responses that contribute to thrombus formation. Tea polyphenol (TP) in the form of epigallocatechin-3-gallate (EGCG) has anti-inflammatory and oxidative effect that may ameliorate DVT. However, the precise mechanism remains incompletely understood. The current study was designed to investigate the anti-DVT mechanism of EGCG in combination with warfarin (an oral anticoagulant). Rabbits were randomly divided into five groups. A DVT model of rats was established through ligation of the inferior vena cava (IVC) and left common iliac vein, and the animals were orally administered with EGCG, warfarin, or vehicle for seven days. In vitro studies included pretreatment of human umbilical vein endothelial cells (HUVECs) with different concentrations of EGCG for 2 h before exposure to hydrogen peroxide. Thrombus weight and length were examined. Histopathological changes were observed by hematoxylin-eosin staining. Blood samples were collected for detecting coagulation function, including thrombin and prothrombin times, activated partial thromboplastin time, and fibrinogen levels. Protein expression in thrombosed IVCs and HUVECs was evaluated by Western blot, immunohistochemical analysis, and/or immunofluorescence staining. RT-qPCR was used to determine the levels of AGTR-1 and VEGF mRNA in IVCs and HUVECs. The viability of HUVECs was examined by CCK-8 assay. Flow cytometry was performed to detect cell apoptosis and ROS generation was assessed by 2',7'-dichlorofluorescein diacetate reagent. In vitro and invivo studies showed that EGCG combined with warfarin significantly reduced thrombus weight and length, and apoptosis in HUVECs. Our findings indicated that the combination of EGCG and warfarin protects HUVECs from oxidative stress and prevents apoptosis. However, HIF-1α silencing weakened these effects, which indicated that HIF-1α may participate in DVT. Furthermore, HIF-1α silencing significantly up-regulated cell apoptosis and ROS generation, and enhanced VEGF expression and the activation of the PI3K/AKT and ERK1/2 signaling pathways. In conclusion, our results indicate that EGCG combined with warfarin modifies HIF-1α and VEGF to prevent DVT in rabbits through anti-inflammation via the PI3K/AKT and ERK1/2 signaling pathways.

Modulation of soluble guanylate cyclase ameliorates pulmonary hypertension in a rat model of chronic thromboembolic pulmonary hypertension by stimulating angiogenesis

Acute pulmonary embolism (PE) does not always resolve after treatment and can progress to chronic thromboembolic disease (CTED) or the more severe chronic thromboembolic pulmonary hypertension (CTEPH). The mechanisms surrounding the likelihood of PE resolution or progress to CTED/CTEPH remain largely unknown. We have developed a rat model of CTEPH that closely resembles the human disease in terms of hemodynamics and cardiac manifestations. Embolization of rats with polystyrene microspheres followed by suppression of angiogenesis with the inhibitor of vascular endothelial growth factor receptor 2 (VEGF-R2) SU5416 results in transient, acute pulmonary hypertension that progresses into chronic PE with PH with sustained right ventricular systolic pressures exceeding 70 mmHg (chronic pulmonary embolism [CPE] model). This model is similar to the widely utilized hypoxia/SU5416 model with the exception that the "first hit" is PE. Rats with CPE have impaired right heart function characterized by reduced VO2 Max, reduced cardiac output, and increased Fulton index. None of these metrics are adversely affected by PE alone. Contrast-mediated CT imaging of lungs from rats with PE minus SU5416 show large increases in pulmonary vascular volume, presumably due to an angiogenic response to acute PE/PH. Co-treatment with SU5416 suppresses angiogenesis and produces the CTEPH-like phenotype. We report here that treatment of CPE rats with agonists for soluble guanylate cyclase, a source of cGMP which is in turn a signal for angiogenesis, markedly increases angiogenesis in lungs, and ameliorates the cardiac deficiencies in the CPE model. These results have implications for future development of therapies for human CTEPH.

Evaluation and management of patients with chronic thromboembolic pulmonary hypertension - consensus statement from the ISHLT

ISHLT members have recognized the importance of a consensus statement on the evaluation and management of patients with chronic thromboembolic pulmonary hypertension. The creation of this document required multiple steps, including the engagement of the ISHLT councils, approval by the Standards and Guidelines Committee, identification and selection of experts in the field, and the development of 6 working groups. Each working group provided a separate section based on an extensive literature search. These sections were then coalesced into a single document that was circulated to all members of the working groups. Key points were summarized at the end of each section. Due to the limited number of comparative trials in this field, the document was written as a literature review with expert opinion rather than based on level of evidence.

Synthetic Fibrin-Derived Bβ15-42 Peptide Delays Thrombus Resolution in a Mouse Model

[Figure: see text].

Dural arteriovenous fistula formation following bilateral middle meningeal artery embolization for the treatment of a chronic subdural hematoma: a case report

Here is reported a case of dural arteriovenous fistula (DAVF) formation following middle meningeal artery (MMA) embolization. A 64-year-old male patient was operated for a bilateral CSDH by burr-hole craniostomy. Prophylactic post-operative MMA embolization was performed with 300-500-μm calibrated microparticles. The patient was admitted 3 months later for a left CSDH recurrence. Digital subtraction angiography demonstrated formation of a superior sagittal sinus DAVF fed by both superficial temporal arteries. This case highlights the possible role of local tissue hypoxia as a significant component of DAVF pathogenesis. Moreover, it has potential implications for MMA embolization as a management strategy for CSDH.

Successful treatment of acquired arteriovenous fistula following iliac vein thrombosis

OBJECTIVES

Cases of arteriovenous fistula following iliac vein thrombosis are uncommon. The pathogenesis of its formation remains unclear. We present the efficacy of left common iliac vein recanalization in acquired arteriovenous fistula treatment.

METHODS

A 71-year-old man presented with severe lower left limb edema and was diagnosed with acquired arteriovenous fistula following iliac vein thrombosis. Treatment by recanalizing the left common iliac vein with bare stents was selected over embolizing the arteriovenous fistula, leading to an excellent clinical outcome.Results and Conclusions: Acquired arteriovenous fistula should be considered in some patients with post-thrombotic syndrome. Endovascular recanalization without embolization of the arteriovenous fistula can effectively treat iliac vein thrombosis associated with arteriovenous fistula.

Adventitial Progenitor Cells of Human Great Saphenous Vein Enhance the Resolution of Venous Thrombosis via Neovascularization

Background

Vascular adventitia contains progenitor cells and is shown to participate in vascular remolding. Progenitor cells are recruited into the venous thrombi in mice to promote neovascularization. We hypothesized that the adventitial progenitor cells of human great saphenous vein (HGSV-AdPC) enhance the resolution of venous thrombosis via neovascularization.

Methods

Human great saphenous vein (HGSV) was harvested from the patients with great saphenous vein varicose and sectioned for immunohistochemistry, or minced for progenitor cell primary culture, or placed in sodium dodecyl sulfate solution for decellularization. Human venous thrombi were collected from patients with great saphenous vein varicose and superficial thrombophlebitis. Infrarenal abdominal aorta of New Zealand white rabbits was replaced with interposing decellularized vessel, and the patency of the grafts was confirmed by ultrasonic examination. Animal venous thrombi in the left infrarenal vena cava of mice were produced with Prolene suture ligation and ophthalmic force clipping of this portion. After HGSVs were digested by collagenase, the CD34⁺CD117⁺ HGSV-AdPC were isolated on FACS system, labelled with CM-Dil, and transplanted into the adventitia of infrarenal vena cava of nude mice. The percentage of thrombus organization area to the thrombus area was calculated as the organization rate. The thrombus cell, endothelial cells, and macrophages in the thrombi were counted in sections. Cell smears and frozen sections of human saphenous veins and venous thrombi were labeled with Sca1, CD34, CD117, Flk1, CD31, and F4/80 antibodies. The CD34⁺CD117⁺ HGSV-AdPC were cultured in endothelial growth medium with vascular endothelial growth factor (VEGF) to induce endothelial cell differentiation and analyzed with real time-PCR, Western blotting, and tube formation assays.

Results

Immunohistochemical staining showed that the CD34⁺CD117⁺ cells were located within the adventitia of HGSVs, and many CD34⁺ and CD117⁺ cells have emerged in the human venous thrombi. The number of progenitor cells within the marginal area of 7 days mice thrombi was shown to be Sca1⁺ ≈21%, CD34⁺ ≈12%, CD117⁺ ≈9%, and Flk1⁺ ≈5%. Many CD34⁺adventitial progenitor cells have migrated into the decellularized vessels. FACS showed that the number of CD34⁺CD117⁺ HGSV-AdPC in primary cultured cells as 1.2 ± 0.07%. After CD34⁺CD117⁺HGSV-AdPC were transplanted into the adventitia of nude mice vena cava with venous thrombi, the organization rate, nucleate cell count, endothelial cells, and macrophage cells of thrombi were shown to be significantly increased. The transplanted CD34⁺CD117⁺ HGSV-AdPC at the adventitia have crossed the vein wall, entered the venous thrombi, and differentiated into endothelial cells. The CD34⁺CD117⁺ HGSV-AdPC in the culture medium in the presence of VEGF-promoted gene and protein expression of endothelial cell markers in vitro and induced tube formation.

Conclusions

HGSV-AdPC could cross the vein wall and migrate from the adventitia into the venous thrombi. Increased HGSV-AdPC in the adventitia has enhanced the resolution of venous thrombi via differentiating into endothelial cells of neovascularization.

Histologic features of thrombosis events with a centrifugal left ventricular assist device

BACKGROUND

Histology of thrombosis events in left ventricular assist devices (LVADs) may point to differences between the etiology of either ingested or de novo thrombus formation within LVADs. Materials ingested by the pump would have features suggestive of lifting and folding, whereas thrombi formed de novo would have uniform, parallel layers. This study tested this hypothesis in a cohort of explanted HeartWare Ventricular assist devices (HVADs) (Medtronic, Miami Lakes, Florida).

METHODS

Histology of thrombi from 59 explanted HVAD pumps were classified as presumed ingested, presumed de novo, or undeterminable on the basis of pre-defined criteria. The apparent size and location of the thrombotic materials were noted.

RESULTS

Histologically, all thrombotic materials were either presumed to be ingested (73%; 95 of 130 total histology cassettes examined) or of undeterminable origin (27%; 35 of 130 histology cassettes). Undetermined origin commonly was due to a lack of sufficient material for analysis. The larger materials (>800 mm³) tended to be in the inflow region. The most common finding was smaller thrombotic materials (<150 mm³) within the pump (64%; 38 of 59 HVADs); when these smaller materials were ingested by the pump, they were most often found within the smaller flow pathways within the pump.

CONCLUSIONS

Our study suggests that the thrombi within HVAD pumps are commonly ingested materials rather than de novo thrombus formation within the pump. Further research to understand the source of this ingested material and the consideration to mitigate this complication should be considered.

De novo arteriovenous shunts after endovascular cure of cerebrospinal macro arteriovenous fistulas. A role for the vasa vasorum?

BACKGROUND AND PURPOSE

Macro-arteriovenous fistulas (MAVFs) are arteriovenous shunts draining into a giant venous ectasia. They can be treated by surgery or embolisation. Angiographic controls are usually performed rapidly after treatment in order to prove the cure of the lesion but no long term angiographies are generally scheduled. We wanted to control the stabilities of such lesions at follow-up.

METHOD

Clinical history and imaging of ninety-five patients with high flow shunts draining into venous ectasias (MAVFs, Vein of Galen malformations and dilatations) were reviewed.

RESULTS

De novo arteriovenous shunts related to angiogenesis involving vasa vasorum developed in three patients with MAVFs at various intervals. Genetic underlying conditions as HHT or RASA 1 mutations were suspected in each patient.

CONCLUSIONS

Neo-angiogenesis can occur after cure of MAVFs. Long term imaging follow-ups should be considered as the natural history of such recurrent shunts is currently unknown.

Research progress on the pathogenesis of CTEPH

Chronic thromboembolic pulmonary hypertension (CTEPH) is an established long-term complication of pulmonary thromboembolism (PTE). However, studies have shown that many patients with a definitive CTEPH diagnosis have no history of symptomatic PTE, suggesting that PTE is not the only cause of CTEPH. Despite extensive progress in research on pulmonary hypertension in recent years, due to a lack of relevant studies on the pathophysiology of CTEPH, implementing pulmonary endarterectomy (PEA) in patients has many challenges, and the prognosis of patients with CTEPH is still not optimistic. Therefore, revealing the pathogenesis of CTEPH would be of great significance for understanding the occurrence and development of CTEPH, developing relevant drug treatment studies and formulating intervention strategies, and may provide new preventive measures. This article summarizes the current research progress in CTEPH pathogenesis from the perspective of risk factors related to medical history, abnormal coagulation and fibrinolytic mechanisms, inflammatory mechanisms, genetic susceptibility factors, angiogenesis, in situ thrombosis, vascular remodeling, and other aspects.

From Acute to Chronic Thromboembolic Disease

After achievement of adequate anticoagulation, the natural history of acute pulmonary emboli ranges from near total resolution of vascular perfusion to long-term persistence of hemodynamically consequential residual perfusion defects. The persistence of perfusion defects is necessary, but not sufficient, for the development of chronic thromboembolic pulmonary hypertension (CTEPH). Approximately 30% of patients have persistent defects after 6 months of anticoagulation, but only 10% of those with persistent defects subsequently develop CTEPH. A number of clinical risk factors including increasing age, delay in anticoagulation from symptom onset, and the size of the initial thrombus have been associated with the persistence of perfusion defects. Likewise, a number of cellular and molecular pathways have been implicated in the failure of thrombus resolution, including impaired fibrinolysis, altered fibrinogen structure and function, increased local or systemic inflammation, and remodeling of the embolic material by neovascularization. Treatment with fibrinolytic agents at the time of initial presentation has not clearly improved the frequency or degree of recovery of pulmonary vascular perfusion. A better understanding of the interplay between clinical risk factors and pathogenic mechanisms may enhance the ability to prevent and treat CTEPH in the future.

Inflammation and peripheral venous disease

The inflammatory response to healing in venous thrombosis might cause vein damage and post-thrombotic syndrome. Inflammation may also be involved in venous insufficiency apart from deep-vein thrombosis. We studied the association of inflammation markers with venous insufficiency in a general population sample. We characterised 2,404 men and women in a general population cohort for peripheral venous disease and its severity using physical exam, symptom assessment, and venous ultrasound. Inflammation markers, C-reactive protein (CRP), fibrinogen, interleukin 1-beta (IL-1-beta), IL-8, IL-10, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, monocyte chemoattractant-1 (MCP-1) and vascular endothelial cell growth factor (VEGF) were compared in 352 case participants with peripheral venous disease and 352 controls with no venous abnormalities frequency matched to cases by age, sex and race. Associations were also evaluated including a subset of 108 cases of severe venous disease, as previously defined. Odds ratios (95% CI), for peripheral venous disease for biomarkers in the top quartile (adjusting for age, race, sex, body mass index and history of venous thrombosis) were 1.8 (1.1–3.0), 1.6 (1.0–2.5) and 1.5 (0.9–2.3) for CRP, fibrinogen and IL-10, respectively. Associations were larger considering cases of severe venous disease, with odds ratios for these three analytes of 2.6 (1.2–5.9), 3.1 (1.3–7.3) and 2.2 (1.1–4.4), and for IL-8: 2.4 (1.1–5.2). There was no association of IL-1-beta, ICAM-1, VCAM-1, E-selectin, MCP-1 or VEGF with overall cases or severe venous disease. In conclusion, a subset of inflammation markers were associated with increased risk of peripheral venous disease, suggesting potential therapeutic targets for treatment.

From thrombosis to fibrosis in chronic thromboembolic pulmonary hypertension

The pathomechanisms underlying the development of thrombofibrotic pulmonary artery occlusions in Chronic Thromboembolic Pulmonary Hypertension (CTEPH) are largely unknown. The aim of this study was to allocate distinct cellular processes playing a role in thrombus resolution, such as inflammation, hypoxia, proliferation, apoptosis and angiogenesis, to different stages of thrombofibrotic remodelling. A total of 182 pulmonary endarterectomy (PEA) specimens were collected from 31 CTEPH patients. To facilitate co-localisation, Tissue MicroArrays were prepared and processed for (immuno)-histochemistry and confocal fluorescence microscopy. Murine venous thrombus formation and resolution was examined after inferior vena cava ligation. PEA tissues exhibited five morphologically distinct regions predominantly consisting of either fibrin-, erythrocyte- or extracellular matrix-rich thrombus, myofibroblasts, vessels or fibrotic tissue, and were found to resemble chronological stages of thrombus resolution in mice. Cellularity was highest in vessel-rich regions, and numerous cells were strongly positive for HIF1α or HIF2α as well as markers of activated VEGF signalling, including endothelial nitric oxide synthase. On the other hand, negative regulators of angiogenic growth factor signalling and reactive oxygen species were also highly expressed. Immune cells, primarily macrophages of the M2 subtype and CD117 haematopoietic progenitors were detected and highest in vascularised regions. Our findings demonstrate the simultaneous presence of different stages of thrombus organisation and suggest that hypoxia-induced endothelial, mesenchymal and immune cell activation may contribute to thrombofibrosis in CTEPH. This systematic histological characterisation of the material obstructing pulmonary vessels in CTEPH may provide a valuable basis for further studies aimed at determining causal factors underlying this disease.

Supplementary Material to this article is available online at www.thrombosis-online.com.

Current understanding of the pathophysiology of chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a unique form of pulmonary hypertension arising from fibrotic obliteration of major pulmonary arteries. Pro-thrombotic states, large clot burden and impaired dissolution are believed to contribute to the occurrence and progression of thrombosis after an acute pulmonary embolic event. Recent data utilizing several models have facilitated the understanding of clot resolution. This review summarizes current knowledge on pathophysiological mechanisms of major vessel occlusion in CTEPH.

Genetic Analysis of Venous Thromboembolism in UK Biobank Identifies the ZFPM2 Locus and Implicates Obesity as a Causal Risk Factor

BACKGROUND

UK Biobank is the world's largest repository for phenotypic and genotypic information for individuals of European ancestry. Here, we leverage UK Biobank to understand the inherited basis for venous thromboembolism (VTE), a leading cause of cardiovascular mortality.

METHODS AND RESULTS

We identified 3290 VTE cases and 116 868 controls through billing code-based phenotyping. We performed a genome-wide association study for VTE with ≈9 000 000 imputed single-nucleotide polymorphisms. We performed a phenome-wide association study for a genetic risk score of 10 VTE-associated variants. To assess whether obesity is a causal factor for VTE, we performed Mendelian randomization analysis using a genetic risk score instrument composed of 68 body mass index-associated variants. The genome-wide association study for VTE replicated previous findings at the F5, F2, ABO, F11, and FGG loci. We identified 1 new locus-ZFPM2 rs4602861-at genome-wide significance (odds ratio, 1.11; 95% confidence interval, 1.07-1.15; P=4.9×10^-10) and a new independent variant at the F2 locus (rs3136516; odds ratio, 1.10; 95% confidence interval, 1.06-1.13; P=7.60×10^-9). In a phenome-wide association study, a 10 single-nucleotide polymorphism VTE genetic risk score was associated with coronary artery disease (odds ratio, 1.08; 95% confidence interval, 1.05-1.10 per unit increase in VTE odds; P=1.08×10^-9). In a Mendelian randomization analysis, genetically elevated body mass index (a 1 SD increase) was associated with 57% higher risk of VTE (odds ratio, 1.57; 95% confidence interval, 1.08-1.97; P=0.003).

CONCLUSIONS

For common diseases such as VTE, biobanks provide potential to perform genetic discovery, explore the phenotypic consequences for disease-associated variants, and test causal inference.

Impact of thrombosis on pulmonary endothelial injury and repair following sepsis

The prevailing morbidity and mortality in sepsis are largely due to multiple organ dysfunction (MOD), most commonly lung injury, as well as renal and cardiac dysfunction. Despite recent advances in defining many aspects of the pathogenesis of sepsis-related MOD, including acute respiratory distress syndrome (ARDS), there are currently no effective pharmacological or cell-based treatments for the disease. Human and animal studies have shown that pulmonary thrombosis is common in sepsis-induced ARDS, and preclinical studies have shown that anticoagulation may improve outcome following sepsis challenge. The potential beneficial effect of anticoagulation on outcome is unconvincing in clinical studies, however, and these discrepancies may arise from the multiple and sometimes opposing actions of thrombosis on the pulmonary endothelium following sepsis. It has been suggested, for example, that mild pulmonary thrombosis prevents escape of bacterial infection into the circulation, while severe thrombosis causes hypoxia and results in pulmonary endothelial damage. Evidence from both human and animal studies has demonstrated the key role of microvascular leakage in determining the outcome of sepsis. In this review, we describe thrombosis-dependent mechanisms that regulate pulmonary endothelial injury and repair following sepsis, including activation of the coagulation cascade by tissue factor and stimulation of vascular repair by hypoxia-inducible factors. Targeting such mechanisms through anticoagulant, anti-inflammatory, and reparative methods may represent a novel approach for the treatment of septic patients.

Current concepts in the pathogenesis of chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by fibrotic obstruction of the proximal pulmonary arteries, and it is believed to result from incomplete thrombus resolution after acute pulmonary embolism. While treatment for this condition with surgery and medical therapy has improved outcomes, our understanding of the molecular mechanisms underlying CTEPH is incomplete. Numerous risk factors have been associated with the development of CTEPH, including but not limited to acquired thrombophilias and chronic inflammatory states. A minority of patients with CTEPH have an abnormal fibrin structure that may delay thrombus resolution. Recently, examination of resected scar material in patients with CTEPH has suggested that deficient angiogenesis may play a role in thrombus nonresolution, and there is increasing interest in factors that drive intravascular scar formation. An additional challenge in CTEPH research is understanding the etiology and implications of the small-vessel disease present in many patients. Future work will likely be directed at understanding the pathways important to disease pathogenesis through further examinations of resected tissue material, continued work on animal models, and genomic approaches to identify alterations in gene expression or gene variants that may distinguish CTEPH from other forms of pulmonary hypertension.

Approach to chemotherapy-associated thrombosis

Treatment of cancer patients with antineoplastic agents is associated with a heightened risk of thrombotic events, both arterial and venous. In this article, we review the specific agents that are implicated and the pathophysiological processes that are known to be associated with this prothrombotic state. We conclude with current recommendations for prophylactic antithrombotic therapy in these clinical situations.

Endothelial colony-forming cells: Biological and functional abnormalities in patients with recurrent, unprovoked venous thromboembolic disease

INTRODUCTION

Endothelial cells (ECs) are an important component of the blood coagulation system because it maintains blood fluid. Because in patients with venous thromboembolic disease (VTD) a thrombophilic condition is not found sometimes, we investigated if endothelial colony-forming cells (ECFCs) from these patients have biological and functional abnormalities.

PATIENTS AND METHODS

Human mononuclear cells (MNCs) were obtained from peripheral blood from patients with VTD and controls to obtain ECFCs. These cells were assayed for their immunophenotype and electron microscopy characteristics and their ability to form capillary-like structures and to produce pro-inflammatory and pro-angiogenic cytokines and reactive oxygen species (ROS).

RESULTS

ECFCs appeared at 7 and 21 days of culture in VTD patients and controls, respectively. ECFCs increased 8-fold in patients and emerged 1 week earlier. No differences in the size of the colonies of ECFCs were found. Numbers and time of appearance of ECFCs was different between groups. ECFC-derived ECs (ECFC-ECs) of both groups expressed CD31, CD34, CD146, and CD-309 but none expressed CD45, CD14, or CD90. Interest CD34 was highly expressed in ECFC-ECs from patients. In both groups, ECFC-ECs showed similar capacity to form capillary-like structures but ECFC-ECs from patients had significant abnormalities in the mitochondrial membrane. We found a significant increase in ROS production in ECFC-ECs from patients. There were significant differences in cytokine profiles between VTD patients and controls.

CONCLUSIONS

We found a dysfunctional state in ECFC from VTD patients resembling some characteristics of dysfunctional ECs. These findings may help to understand some pathophysiological aspects of VTD.

The Dural AV-Fistula (DAVF), the Most Frequent Acquired Vascular Malformation of the Central Nervous System (CNS)

Acquired arteriovenous malformations, such as is the case with dural arteriovenous fistulae (DAVF), are the consequence of a pathological new arterial ingrowth into venous spaces that reaches directly the venous lumen, without interposition of a capillary network, thereby creating an AV-shunt.The following concise text will provide elements in regards to diagnosis, indication for treatment discussion and choice of endovascular treatment (EVT) method.

Contribution of inflammation and impaired angiogenesis to the pathobiology of chronic thromboembolic pulmonary hypertension

Deficient angiogenesis and systemic inflammation could be involved in the pathophysiology of chronic thromboembolic pulmonary hypertension (CTEPH). We aimed to characterise the histopathology of pulmonary vascular lesions from 52 CTEPH patients who underwent a pulmonary endarterectomy (PEA) and investigate a potential link between clinical, biological and morphometric parameters.

Collagen, elastin, fibrin, lipid, endothelial, smooth muscle and inflammatory cell content was investigated using immunohistochemistry. Qualitative changes were evaluated using severity scores. Circulating levels of inflammatory mediators were measured using ELISA.

Neointima, thrombotic, recanalised and atherosclerotic lesions were found. Accumulation of macrophages, T-lymphocytes and neutrophils was found mainly in atherosclerotic and thrombotic lesions. Angiogenesis was observed in all kinds of lesions; low-scored angiogenesis predicted adverse outcome, including persistent pulmonary hypertension post-PEA, start of medical therapy and poor survival. C-reactive protein (CRP), interleukin-10, monocyte chemotactic protein-1, macrophage inflammatory protein-1α and matrix metalloproteinase (MMP)-9 were significantly elevated in CTEPH patients. Plasma CRP and MMP-9 levels correlated with neutrophil and macrophage accumulation, respectively.

Enhanced systemic inflammation parallels local inflammatory cell infiltration in major pulmonary arteries at advanced stages of CTEPH. Impaired neovascularisation is associated with poor survival, start of medical treatment and persistent pulmonary hypertension post-PEA. These findings suggest that inflammation and impaired angiogenesis could contribute to the progression of the disease.

Predictive value of markers of inflammation in the postthrombotic syndrome: a systematic review: inflammatory biomarkers and PTS

BACKGROUND

The postthrombotic syndrome (PTS) is a chronic complication of deep vein thrombosis (DVT). Inflammation may contribute to its pathophysiology.

OBJECTIVES

We conducted a systematic review of studies that analyzed the association between biomarkers of inflammation and PTS in DVT patients.

METHODS

The electronic databases PubMed, EMBASE, Medline, Scopus and Web of Science were searched for studies published until March 2015 that measured blood inflammation biomarker levels in adult DVT patients and reported their association with PTS development. Two reviewers independently performed full text assessment and data extraction.

RESULTS

Ten studies were included. Nine reported on the association between C-reactive protein and PTS; Interleukin (IL)-6 was measured in six studies; IL-8 in four studies; Intracellular adhesion molecule (ICAM)-1 in three studies; IL-10 and vascular cell adhesion molecule-1 in two studies; and monocyte chemotactic protein-1, matrix metalloprotease-9, P-Selectin, tumor necrosis factor α and erythrocyte sedimentation rate were measured in one study. Studies differed in terms of populations included, exclusion criteria, methods used for biomarker measurement and statistical measures of association between biomarkers and PTS. We were able to metaanalyze results only for IL-6 and found no significant association. Descriptively, ICAM-1 was significantly associated with PTS in two out of three studies that measured it. Other biomarkers did not demonstrate a significant association with PTS.

CONCLUSIONS

Our systematic review found conflicting results regarding the role of inflammatory biomarkers as predictors of PTS. ICAM -1 appears to be a promising marker for further investigation.

Chronic thromboembolic pulmonary hypertension: a distinct disease entity

Chronic thromboembolic pulmonary hypertension (CTEPH) is a distinct subtype of pulmonary hypertension (PH). One disease hypothesis is that CTEPH results from the non-resolution of venous thromboembolism. CTEPH is characterised by the presence of obstructive fibrotic thromboembolic material in the major pulmonary vessels, with concomitant microvascular arteriopathy, resulting in progressive PH. The clinical presentation of CTEPH is similar to pulmonary arterial hypertension with nonspecific symptoms, but it is distinguished from pulmonary arterial hypertension by the presence of mismatched segmental defects on the ventilation/perfusion scan. The exact prevalence and incidence of CTEPH are unknown, but are thought to have been underestimated in the past. CTEPH is unique among the subgroups of PH in that it is potentially curable with pulmonary endarterectomy, a surgical intervention intended to remove the occlusive material from the pulmonary vasculature. However, in some patients the obstructions are technically inaccessible or the risk/benefit ratios are unfavourable, making the condition inoperable. It is thought that the involvement of the smaller, more distal vessels is a target for medical treatment. Untreated, CTEPH may result in right heart failure and death. The pathophysiological mechanisms which cause CTEPH are complex and have not yet been fully elucidated.

CTEPH is distinct from other types of pulmonary hypertension, both in terms of its pathophysiology and treatmenthttp://ow.ly/L54ag

Why acute pulmonary embolism becomes chronic thromboembolic pulmonary hypertension: clinical and genetic insights

PURPOSE OF REVIEW

Chronic thromboembolic pulmonary hypertension (CTEPH) is a life-threatening complication that affects a small but appreciable percentage of patients after acute pulmonary embolism. The cause of CTEPH is under investigation, but no single causative mechanism has yet been identified.

RECENT FINDINGS

CTEPH is likely a complication of residual thrombotic material in the pulmonary arteries that becomes transformed into intravascular scars. Pulmonary artery residua are relatively common after acute pulmonary embolism, and CTEPH may be an extreme manifestation of this phenomenon. Several intriguing observations have been made in patients with CTEPH that give insights into the mechanisms responsible for its formation. Two general pathways have been investigated: resistance of thromboemboli to lysis and attenuation of cellular processes involved in thrombus resolution. This review discusses the evidence supporting each pathway as a mechanism for CTEPH formation, as well as the interaction between the two.

SUMMARY

CTEPH may be due to a complex interaction between thrombotic/thrombolytic processes and angiogenic cellular remodeling of organized thrombi. The factors involved may, in fact, vary among CTEPH patients. An understanding of the interplay between the factors that cause CTEPH may help quantify the risk of its occurrence and provide insights into how it can be prevented.

Defective angiogenesis delays thrombus resolution: a potential pathogenetic mechanism underlying chronic thromboembolic pulmonary hypertension

OBJECTIVE

Restoration of patency is a natural target of vascular remodeling after venous thrombosis that involves vascular endothelial cells and smooth muscle cells, as well as leukocytes. Acute pulmonary emboli usually resolve <6 months. However, in some instances, thrombi transform into fibrous vascular obstructions, resulting in occlusion of the deep veins, or in chronic thromboembolic pulmonary hypertension (CTEPH). We proposed that dysregulated thrombus angiogenesis may contribute to thrombus persistence.

APPROACH AND RESULTS

Mice with an endothelial cell-specific conditional deletion of vascular endothelial growth factor receptor 2/kinase insert domain protein receptor were used in a model of stagnant flow venous thrombosis closely resembling human deep vein thrombosis. Biochemical and functional analyses were performed on pulmonary endarterectomy specimens from patients with CTEPH, a human model of nonresolving venous thromboembolism. Endothelial cell-specific deletion of kinase insert domain protein receptor and subsequent ablation of thrombus vascularization delayed thrombus resolution. In accordance with these findings, organized human CTEPH thrombi were largely devoid of vascular structures. Several vessel-specific genes, such as kinase insert domain protein receptor, vascular endothelial cadherin, and podoplanin, were expressed at lower levels in white CTEPH thrombi than in organizing deep vein thrombi and organizing thrombi from aortic aneurysms. In addition, red CTEPH thrombi attenuated the angiogenic response induced by vascular endothelial growth factor.

CONCLUSIONS

In the present work, we propose a mechanism of thrombus nonresolution demonstrating that endothelial cell-specific deletion of kinase insert domain protein receptor abates thrombus vessel formation, misguiding thrombus resolution. Medical conditions associated with the development of CTEPH may be compromising early thrombus angiogenesis.

Chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a disease with high mortality and few treatment options. This article reviews the epidemiology of CTEPH and identifies risk factors for its development. The pathobiology and the progression from thromboembolic events to chronically increased right-sided pressures are discussed. The diagnosis and assessment of CTEPH requires several modalities and the role of these is detailed. The pre-operative evaluation assesses peri-operative risk and determines the likelihood of benefit from PTE. Pulmonary thromboendarterectomy (PTE) remains the treatment of choice in appropriate patients. Nonsurgical therapies for CTEPH may provide benefit in patients who cannot be offered surgery.

Early onset of endothelial cell proliferation in coronary thrombi of patients with an acute myocardial infarction: implications for plaque healing

AIMS

Coronary thrombotic occlusion in ST-segment elevation myocardial infarction (STEMI) patients is often preceded by episodes of progressive growth of the thrombus mass. Similar to wound healing, the organization of thrombus could depend on ingrowth of microvessels in order to stabilize its structure. We investigated the patterns of neovascularization in different stages of coronary thrombus evolution.

MATERIAL AND METHODS

Thrombectomy materials obtained from STEMI patients were histologically classified according to thrombus age in three groups: fresh (< 1 day), lytic (1-5 days) or organized (> 5 days) thrombi. Forty thrombi of each group were randomly collected. Neovascularization in the thrombi was evaluated histomorphologically and with immunodouble stains to visualize various differentiation antigens of endothelial cells (ECs) and primitive cells.

RESULTS

Morphologically, ECs in the coronary thrombi manifested as: single cells, cell clusters or microvessels. CD31+/CD34+ ECs were present in 98% of all the thrombi. In addition, endothelial clusters were found in 63% of the fresh thrombi (< 1 day). CD105+, Ki67+, or C-kit+ ECs (active, proliferating cells) were observed in all the stages, but significantly more in organized thrombi (> 5 days) compared with fresh and lytic ones (< 5 days), and mainly as cell clusters (P ≤ 0.05 for all). CD133+ primitive cells were found only sporadically in 11% of all the samples.

CONCLUSION

EC proliferation is initiated very early, and gradually progresses during the organization process of thrombus after coronary plaque disruption, with only a limited contribution of primitive cells in this process.

Absence of IFN-γ accelerates thrombus resolution through enhanced MMP-9 and VEGF expression in mice

Deep vein thrombosis (DVT) is a major cause of pulmonary thromboembolism, a leading cause of death in individuals with DVT. Several lines of evidence indicate proinflammatory cytokines such as TNF-α are involved in thrombus formation and resolution, but the roles of IFN-γ remain unclear. To address this issue, we performed ligation of the inferior vena cava to induce DVT in WT and IFN-γ-deficient (Ifng-/-) mice. In WT mice, intrathrombotic IFN-γ levels were elevated progressively as the postligation interval was extended. Thrombus size was substantially smaller at 10 and 14 days in Ifng-/- mice than in WT mice. Intrathrombotic collagen content was remarkably reduced at more than 10 days after the ligation in Ifng-/- mice compared with WT mice. The expression and activity of MMP-9, but not MMP-2, was higher at the late phase in Ifng-/- mice than in WT mice. Moreover, intrathrombotic recanalization was increased in Ifng-/- mice, with enhanced Vegf gene expression, compared with that in WT mice. Activation of the IFN-γ/Stat1 signal pathway suppressed PMA-induced Mmp9 and Vegf gene expression in peritoneal macrophages. Furthermore, administration of anti-IFN-γ mAbs accelerated thrombus resolution in WT mice. Collectively, these findings indicate that IFN-γ can have detrimental roles in thrombus resolution and may be a good molecular target for the acceleration of thrombus resolution in individuals with DVT.

Upregulation of hypoxia-inducible factor 1 alpha in local vein wall is associated with enhanced venous thrombus resolution

Introduction

Venous thrombus resolution may be regulated by an angiogenic process that involves the surrounding vein wall. The aims of this study were to determine whether: (i) thrombosis stimulates activation of the angiogenic transcription factor, hypoxia-inducible factor (HIF) 1α, and downstream expression of growth factors in vein wall; and (ii) upregulation of HIF1α in vein wall leads to increased growth factor expression and enhanced thrombus resolution.

Materials and methods

HIF1α, vascular endothelial growth factor (VEGF), and placental growth factor (PLGF) were quantified in mouse inferior vena cava (IVC) at days 1, 3, 7, and 14 after thrombus formation (n = 10-13 per group). An additional group of thrombosed mice were treated with the prolyl-hydroxylase domain (PHD) inhibitor, L-mimosine (L-mim) or vehicle control. HIF1α, VEGF, and PLGF in IVC were measured at days 1 and 7; and vein recanalisation and thrombus resolution were measured at days 7 and 10 (n = 6-7 per group).

Results

HIF1α was expressed in thrombosed IVC and its levels remained relatively constant throughout natural resolution. The levels of VEGF in thrombosed IVC were elevated at days 1 (P < 0.0001) and 3 (P < 0.05); and PLGF at days 1 (P < 0.0001), 3 (P < 0.0001), and 7 (P < 0.0001). Treatment with L-mim led to: increased HIF1α (P < 0.05), VEGF (P < 0.005), and PLGF (P < 0.001) levels in the IVC; decreased thrombus size (P < 0.01); and increased vein recanalisation (P < 0.001).

Conclusions

HIF1α levels in vein wall are not affected by thrombosis and it appears that the angiogenic drive in the vein surrounding resolving thrombus is regulated independently of HIF1α. Stimulating HIF1α levels in the vein wall leads to an increased angiogenic drive and promotes vein recanalisation and thrombus resolution.

Transplantation of Ex Vivo Expanded Bone Marrow-Derived Endothelial Progenitor Cells Enhances Chronic Venous Thrombus Resolution and Recanalization

Background: Preclinical and clinical studies indicated that endothelial progenitor cells (EPCs) enhanced blood vessel formation in many clinical situations. However, whether transplantation of EPCs would enhance chronic venous thrombus recanalization and resolution is unknown. Methods: Mononuclear cells were isolated from bone marrow of immature rats by density gradient centrifugation, cultured, and then transplanted into inferior vena cava of rats with experimentally induced thrombi. Vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), messenger RNA (mRNA), and protein expression levels were measured through real-time quantitative polymerase chain reaction and Western blotting of thrombi and adjacent caval walls 14 days following transplantation. Results: Transplantation of bone marrow-derived EPCs led to an increase in VEGF, bFGF, mRNA, and protein expression. In addition, transplantation of bone marrow-derived EPCs also resulted in reduced thrombus size and increased neovascularization in the specimen. Conclusions: Transplanted bone marrow-derived EPCs may be a therapeutic option for treating deep venous thrombosis.

Effects of disturbed flow on vascular endothelium: pathophysiological basis and clinical perspectives

Vascular endothelial cells (ECs) are exposed to hemodynamic forces, which modulate EC functions and vascular biology/pathobiology in health and disease. The flow patterns and hemodynamic forces are not uniform in the vascular system. In straight parts of the arterial tree, blood flow is generally laminar and wall shear stress is high and directed; in branches and curvatures, blood flow is disturbed with nonuniform and irregular distribution of low wall shear stress. Sustained laminar flow with high shear stress upregulates expressions of EC genes and proteins that are protective against atherosclerosis, whereas disturbed flow with associated reciprocating, low shear stress generally upregulates the EC genes and proteins that promote atherogenesis. These findings have led to the concept that the disturbed flow pattern in branch points and curvatures causes the preferential localization of atherosclerotic lesions. Disturbed flow also results in postsurgical neointimal hyperplasia and contributes to pathophysiology of clinical conditions such as in-stent restenosis, vein bypass graft failure, and transplant vasculopathy, as well as aortic valve calcification. In the venous system, disturbed flow resulting from reflux, outflow obstruction, and/or stasis leads to venous inflammation and thrombosis, and hence the development of chronic venous diseases. Understanding of the effects of disturbed flow on ECs can provide mechanistic insights into the role of complex flow patterns in pathogenesis of vascular diseases and can help to elucidate the phenotypic and functional differences between quiescent (nonatherogenic/nonthrombogenic) and activated (atherogenic/thrombogenic) ECs. This review summarizes the current knowledge on the role of disturbed flow in EC physiology and pathophysiology, as well as its clinical implications. Such information can contribute to our understanding of the etiology of lesion development in vascular niches with disturbed flow and help to generate new approaches for therapeutic interventions.

Bone quality: a reality for the process of osseointegration

This article subscribes to the initial condition of bone quality and its ultimate effect on the success of dental implant treatment. A high success rate for the preservation of the alveolar bone around oral implants is predicated on good bone quality. For implantologists, the classification of bone quality should be based on the key elements required for osseointegration. These include structural morphology and cellular characteristics such as monocytes/macrophages, mesenchymal progenitor cells, fibroblasts, osteoclasts, and cells associated with angiogenesis.

Adenovirus-Mediated VEGF Gene Therapy Enhances Venous Thrombus Recanalization and Resolution

Objective— Rapid thrombus recanalization reduces the incidence of post–thrombotic complications. This study aimed to discover whether adenovirus-mediated transfection of the vascular endothelial growth factor gene (ad.VEGF) enhanced thrombus recanalization and resolution.

Methods and Results— In rats, thrombi were directly injected with either ad.VEGF (n=40) or ad.GFP (n=37). Thrombi in SCID mice (n=12) were injected with human macrophages transfected with ad.VEGF or ad.GFP. Thrombi were analyzed at 1 to 14 days. GFP was found mainly in the vein wall and adventitia by 3 days, but was predominantly found in cells within the body of thrombus by day 7. VEGF levels peaked at 4 days (376±299 pg/mg protein). Ad.VEGF treatment reduced thrombus size by >50% (47.7±5.1 mm 2 to 22.0±4.0 mm 2 , P =0.0003) and increased recanalization by >3-fold (3.9±0.69% to 13.6±4.1%, P =0.024) compared with controls. Ad.VEGF treatment increased macrophage recruitment into the thrombus by more than 50% ( P =0.002). Ad.VEGF-transfected macrophages reduced thrombus size by 30% compared with controls (12.3±0.89 mm 2 to 8.7±1.4 mm 2 , P =0.04) and enhanced vein lumen recanalization (3.39±0.34% to 5.07±0.57%, P =0.02).

Conclusion— Treatment with ad.VEGF enhanced thrombus recanalization and resolution, probably as a consequence of an increase in macrophage recruitment.

Recombinant human granulocyte colony-stimulating factor enhanced the resolution of venous thrombi

BACKGROUND

Bone marrow-derived cells are recruited into the thrombus during resolution. This study explored whether mobilization of bone marrow cells with recombinant human granulocyte colony-stimulating factor (rhG-CSF) could enhance the resolution of venous thrombi and the accumulation of macrophages in thrombi and explored the effect of rhG-CSF on cysteine-cysteine chemokine receptor 2 (CCR2) expression.

METHODS

The Sprague-Dawley adult rats were randomly divided into four groups: control, sham-operated, thrombus, and treatment groups. Thrombi were induced in the thrombus and treatment group, which received a subcutaneous injection of rhG-CSF once daily for 6 days postoperatively. The thrombus, sham-operated, and control groups received equal volumes of 0.9% saline. The mononuclear cells in peripheral blood were analyzed by an automated hematology analyzer and counted under microscope. The cell marker CD68 was used to determine the number of macrophages in thrombi tissue sections. Levels of monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP1alpha) in the peripheral blood were detected by enzyme-linked immunosorbent assay. Real-time reverse transcriptase-polymerase chain reaction and Western blot were used to analyze, respectively, the expression of CCR2 messenger RNA in the peripheral blood and CCR2 protein of THP-1 monocyte.

RESULTS

At postoperative days 3 (P < .05) and 7 (P < .01), mononuclear cells significantly increased in treatment group (2.1 +/- 0.3, 4.4 +/- 0.3 x 10(6)/L) vs the thrombus group (1.7 +/- 0.2, 1.3 +/- 0.4 x 10(6)/L). The organization and recanalization of thrombi in treatment group progressed more quickly compared with the thrombus group (P < .01). The macrophage number of the thrombus in the treatment group (338 +/- 26 cells/15 high-power fields) increased significantly vs the thrombus group (125 +/- 11 cells/15 high-power fields, P < .01). No statistical difference was observed between the thrombus and treatment group in the MCP-1 and MIP-1alpha level in peripheral blood. Expressions of the CCR2 gene in the peripheral blood of the treatment group significantly increased compared with the thrombus group (P < .05). Recombinant human G-CSF induced higher expression of CCR2 protein of human monocytic cell line THP-1.

CONCLUSIONS

Bone marrow mobilization enhanced the resolution and recanalization of venous thrombi. This process was associated with increased macrophage accumulation in thrombi, which might be the result of higher CCR2 expression of monocytes.

CLINICAL RELEVANCE

The classic treatment of venous thrombi is anticoagulation. Anticoagulant therapy and thrombolysis both have limited effects on existing thrombi and have a small but significant risk of severe hemorrhage. In clinical practice, we lack specific treatment for patients with venous thrombosis combined with brain hemorrhage or a gastrointestinal activated ulcer, which are contraindicated for anticoagulation and thrombolytic therapy. Enhancing the resolution of venous thrombi would contribute to its therapy. Bone marrow-derived cells are recruited into the thrombus during resolution. Many of these cells express a macrophage phenotype and may represent a population of plastic stem cells that orchestrate thrombus recanalization. Recombinant human granulocyte colony stimulating factor (rhG-CSF) can mobilize monocytic lineage cells into peripheral blood and may contribute to this cell in the thrombi. If rhG-CSF enhances the resolution of venous thrombi and recanalization, it might be used to treat patients with venous thrombi, especially those who have contraindication for anticoagulation and thrombolytic therapy.