von Willebrand factor: the old, the new and the unknown

Von Willebrand Factor Multimer Densitometric Analysis: Validation of the Clinical Accuracy and Clinical Implications in Von Willebrand Disease

Von Willebrand factor (VWF) multimer analysis is important in the classification of von Willebrand disease (VWD). Current visual VWF multimer analysis is time consuming and inaccurate in detecting subtle changes in multimer patterns. Although VWF multimer densitometric analysis may be useful, the accuracy needs further investigation before it can be widely applied. In this study we aimed to validate VWF multimer densitometric analysis in a large cohort of VWD patients and to identify patient characteristics associated with densitometric outcomes. Patients were included from the Willebrand in the Netherlands (WiN) study, in which a bleeding score (BS) was obtained, and blood was drawn. For multimer analysis, citrated blood was separated on an agarose gel and visualized by Western blotting. IMAGEJ was used to generate densitometric images and medium-large VWF multimer index was calculated. We included 560 VWD patients: 328 type 1, 211 type 2, and 21 type 3 patients. Medium-large VWF multimer index performed excellent in distinguishing visually classified normal VWF multimers from reduced high-molecular-weight (HMW) multimers (area under the curve [AUC]: 0.96 [0.94-0.98], P < 0.001), normal multimers from absence of HMW multimers (AUC 1.00 [1.00-1.00], P < 0.001), and type 2A and 2B from type 2M and 2N (AUC: 0.96 [0.94-0.99], P < 0.001). Additionally, higher medium-large VWF multimer index was associated with lower BS in type 1 VWD: β = -7.6 (-13.0 to -2.1), P = 0.007, adjusted for confounders. Densitometric analysis of VWF multimers had an excellent accuracy compared with visual multimer analysis and may contribute to a better understanding of the clinical features such as the bleeding phenotype of VWD patients.

Circulating Von Willebrand factor and high molecular weight multimers as markers of endothelial injury predict COVID-19 in-hospital mortality

Background

Coronavirus disease 2019 (COVID-19) is a respiratory disease associated with endotheliitis and microthrombosis.

Objectives

To correlate endothelial dysfunction to in-hospital mortality in a bi-centric cohort of COVID-19 adult patients.

Methods

Consecutive ambulatory and hospitalized patients with laboratory-confirmed COVID-19 were enrolled. A panel of endothelial biomarkers and von Willebrand factor (VWF) multimers were measured in each patient ≤ 48 h following admission.

Results

Study enrolled 208 COVID-19 patients of whom 23 were mild outpatients and 189 patients hospitalized after admission. Most of endothelial biomarkers tested were found increased in the 89 critical patients transferred to intensive care unit. However, only von Willebrand factor antigen (VWF:Ag) scaled according to clinical severity, with levels significantly higher in critical patients (median 507%, IQR 428–596) compared to non-critical patients (288%, 230–350, p < 0.0001) or COVID-19 outpatients (144%, 133–198, p = 0.007). Moreover, VWF high molecular weight multimers (HMWM) were significantly higher in critical patients (median ratio 1.18, IQR 0.86–1.09) compared to non-critical patients (0.96, 1.04–1.39, p < 0.001). Among all endothelial biomarkers measured, ROC curve analysis identified a VWF:Ag cut-off of 423% as the best predictor for in-hospital mortality. The accuracy of VWF:Ag was further confirmed in a Kaplan–Meier estimator analysis and a Cox proportional Hazard model adjusted on age, BMI, C-reactive protein and d-dimer levels.

Conclusion

VWF:Ag is a relevant predictive factor for in-hospital mortality in COVID-19 patients. More than a biomarker, we hypothesize that VWF, including excess of HMWM forms, drives microthrombosis in COVID-19.

Acquired von Willebrand syndrome and factor VIII in patients with moderate to severe mitral regurgitation undergoing transcatheter mitral valve repair

Background and Hypothesis

The acquired von Willebrand syndrome (AvWS), which predisposes to bleeding events, is often related to valvular heart diseases. We investigated possible implications of AvWS and factor VIII levels in patients with moderate to severe mitral regurgitation (MR) undergoing transcatheter mitral valve repair (TMVR).

Methods and Results

123 patients with moderate to severe MR were prospectively enrolled. Complete measurements of von Willebrand Factor activity (vWFAct), von Willebrand Factor antigen (vWFAg), and factor VIII expression before and 4 weeks after TMVR were available in 85 patients. At baseline, seven patients had a history of gastrointestinal bleeding, two patients suffered bleeding events during their hospital stay, and one patient had a bleeding 4 weeks after TMVR. Even though vWFAct, vWFAct/vWFAg ratio and vWFAg values did not change after TMVR, we observed a significantly lower vWFAct/vWFAg ratio in patients with primary MR as compared to patients with secondary MR both at baseline (p = 0.022) and 4 weeks following the TMVR procedure (p = 0.003). Additionally, patients with a mean mitral valve gradient ≥4 mmHg after TMVR had significantly lower vWFAct/vWFAg ratios as compared to patients with a mean mitral valve gradient <4 mmHg (p = 0.001).

Conclusions

MR of primary etiology was associated with lower vWFAct/vWFAg ratio, hinting toward HMWM loss due to shear stress caused by eccentric regurgitation jets. In addition, morphological changes leading to postprocedural transmitral gradients ≥4 mmHg were related to lower vWFAct/vWFAg ratio 4 weeks after the procedure. Alterations of the vWFAct/vWFAg ratio in turn did not translate into a greater risk for bleeding events.

Association between ADAMTS13 activity-VWF antigen imbalance and the therapeutic effect of HAIC in patients with hepatocellular carcinoma

BACKGROUND

Prediction of HAIC treatment response is important for improving the prognosis in patients with hepatocellular carcinoma (HCC). The progression of HCC is related to hypercoagulability and angiogenesis. It is known that ADAMTS13 and von Willebrand factor (VWF) are related to hypercoagulability. In addition, previous study reported that the association between ADAMTS13 and VWF, and angiogenesis via vascular endothelial growth factor (VEGF). Recently, ADAMTS13 and VWF have been associated with the prognosis in patients with various kinds of cancer undergoing chemotherapy.

AIM

To investigate whether ADAMTS13 and VWF become useful biomarkers of treatment response in HCC patients before the initiation of HAIC treatment.

METHODS

Seventy-two patients were enrolled in this study. ADAMTS13 activity (ADAMTS13:AC), VWF antigen (VWF:Ag) and VEGF levels were determined via enzyme-linked immunosorbent assay. Univariable and multivariable analyses were performed to determine the predictive factors of treatment response in patients with HCC undergoing HAIC treatment.

RESULTS

ADAMTS13:AC levels in HCC patients with stable disease (SD) + partial response (PR) of HAIC treatment were significantly higher than those with progressive disease (PD) (P < 0.05). In contrast, VWF:Ag/ADAMTS13:AC ratio and VEGF levels in HCC patients with SD + PR were significantly lower than those with PD (both P < 0.05). Patients with high VWF:Ag/ADAMTS13:AC ratio (> 2.7) had higher VEGF levels than those with low ratio (≤ 2.7). Multivariable analysis revealed that VWF:Ag/ADAMTS13:AC ratio was a predictive factor of HAIC treatment response.

CONCLUSION

VWF:Ag/ADAMTS13:AC ratio may become a useful biomarker of treatment response in HCC patients before the initiation of HAIC treatment.

The regulation of cartilage extracellular matrix homeostasis in joint cartilage degeneration and regeneration

Osteoarthritis (OA) is a major cause of disability and socioeconomic loss worldwide. However, the current pharmacological approaches used to treat OA are largely palliative. Being the hallmark of OA, the cartilage extracellular matrix (ECM) destruction and abnormal homeostasis is gaining more attention as a therapeutic target in cartilage regeneration. Moreover, during the progression of OA, the cartilage ECM shows significant pathological alternations, which can be promising biomarkers in identifying the pathological stages of OA. In this review, we summarize the role of abnormal ECM homeostasis in the joint cartilage during OA. Furthermore, we provide an update on the cartilage ECM derived biomarkers and regenerative medicine therapies targeting cartilage ECM which includes preclinical animal models study and clinical trials.

Venous thrombosis risk factors in pregnant women

OBJECTIVES

Assess all risk factors of venous thromboembolism (VTE) in pregnancy and puerperium.

METHODS

Different guidelines for VTE prevention have been analyzed.

RESULTS

Various recommendations have appeared for practitioners during the last 10-15 years on the basis of the risk factors analysis in order to prevent VTE in pregnant women more effectively. Nevertheless, none of these recommendations can yet take into account all risk factors, although convenient scoring systems have emerged for risk assessment and clear recommendations on anti-thrombotic prophylaxis regimens in risk groups in recent years.

CONCLUSIONS

VTE is the third most common cause of death on Earth after myocardial infarctions and strokes, according to the World Health Organization. Pregnancy is a unique condition of woman, when enormous changes occur in functioning of the most important systems of homeostasis in a relatively short time. These are physiological hypercoagulation, slowing of blood flow, increase in circulating blood volume, etc. However, while being physiological, these changes increase the risks of venous thromboembolism by almost six times. In some cases, there appears an imbalance or dissociation between the functioning of natural antithrombotic systems and the activation of coagulation as a consequence of genetically or acquired determined causes (genetic thrombophilia, antiphospholipid syndrome, comorbidities, obstetric complications and other exogenous and endogenous factors). Accordingly, identification of risk factors, their systematization, and determination of VTE risks in pregnancy and puerperium is one of the most important tasks of clinical medicine. This article will review historical understanding of thrombosis in pregnant women, progress in understanding VTE risk factors in pregnant women, and available reserves in identifying new risk factors during pregnancy and puerperium in order to stratify risks more efficiently.

Camelid-derived single-chain antibodies in hemostasis: Mechanistic, diagnostic, and therapeutic applications

Hemostasis is a complex process involving the concerted action of molecular and vascular components. Its basic understanding as well as diagnostic and therapeutic aspects have greatly benefited from the use of monoclonal antibodies. Interestingly, camelid-derived single-domain antibodies (sdAbs), also known as VHH or nanobodies, have become available during the previous 2 decades as alternative tools in this regard. Compared to classic antibodies, sdAbs are easier to produce and their small size facilitates their engineering and functionalization. It is not surprising, therefore, that sdAbs are increasingly used in hemostasis-related research. In addition, they have the capacity to recognize unique epitopes unavailable to full monoclonal antibodies. This property can be used to develop novel diagnostic tests identifying conformational variants of hemostatic proteins. Examples include sdAbs that bind active but not globular von Willebrand factor or free factor VIIa but not tissue factor-bound factor VIIa. Finally, sdAbs have a high therapeutic potential, exemplified by caplacizumab, a homodimeric sdAb targeting von Willebrand factor that is approved for the treatment of thrombotic thrombocytopenic purpura. In this review, the various applications of sdAbs in thrombosis and hemostasis-related research, diagnostics, and therapeutic strategies will be discussed.

Impact of significant paravalvular leaks after transcatheter aortic valve implantation on anaemia and mortality

OBJECTIVE

The aim of this work is to assess the relationship between significant paravalvular leak (SPL) after transcatheter aortic valve implantation (TAVI) on anaemia and their impact on prognosis.

METHODS

Observational analytic study developed at two university hospitals, including all consecutive patients who underwent TAVI during a 10-year period (2009 to 2018). A logistic regression model was created to determine independent predictors of anaemia at 3 months. Time to event outcomes were analysed with Cox regression. Median follow-up was 21.3±21.9 months.

RESULTS

788 patients were included. 5.3% had SPL. SPL was an independent predictor of anaemia 3 months after TAVI (OR: 8.31, 95% CI: 2.06 to 33.50). SPL and anaemia at 3 months were independently associated with long-term mortality (HR: 1.82, 95% CI: 1.16 to 2.85; HR: 2.07, 95% CI: 1.39 to 3.08).

CONCLUSION

SPL is an independent predictor of anaemia at 3 months after TAVI, a condition that doubles long-term mortality. Our findings could explain in part the worse prognosis of SPL after TAVI. Further pathophysiological studies are necessary to explain this association.

Management of von Willebrand disease with a factor VIII-poor von Willebrand factor concentrate: Results from a prospective observational post-marketing study

BACKGROUND

A triple-secured plasma-derived von Willebrand factor (pdVWF) almost devoid of factor VIII (FVIII):WILFACTIN® , was approved in France in 2003, and then in other countries for the treatment of patients with von Willebrand disease (VWD).

OBJECTIVE

To investigate long-term safety and efficacy of the product in real-life over the first 5 post-approval years.

PATIENTS/METHODS

This prospective, observational, national post-marketing study (PMS) enrolled patients of all ages and VWD types. Patients were observed for up to 3 years and treated for one or more occasions. Efficacy was assessed for each major event. Breakthrough bleeding rate 3 days post-infusion and annualized bleeding rate (ABR) were also evaluated for long-term prophylaxis.

RESULTS

Overall, 155 of 174 patients enrolled from 31 centers were eligible for efficacy assessment. Most patients (76.8%) were severely affected (VWF:RCo ≤ 15 IU/dL). They were treated for 743 bleeds and 140 surgeries including childbirth. Efficacy outcomes were excellent/good for 98.2% of 56 major surgeries and 94.0% of 67 major bleeds. Approximately 75% of 49 major mucosal bleeds were effectively managed without FVIII co-administration. In 32 patients receiving prophylaxis, breakthrough bleeding occurred in 1.5% of infusions and median ABR was 1.0 for 20 patients treated ≥ 12 months. Excellent tolerability was confirmed with no safety concerns. No thrombotic events were observed.

CONCLUSIONS

Results from this PMS increase the clinical experience of a FVIII-poor pdVWF in patients of all ages and VWD types including those with thrombotic risk factors and emphasize that giving FVIII is not always mandatory to effectively treat patients with severe VWD.

Modulatory properties of cardiac and quercetin glycosides from Dacryodes edulis seeds during L-NAME-induced vascular perturbation

Background Numerous food wastes have been identified to possess potent bioactive compounds used for the treatment of several diseases. Therefore this study evaluated the potentials of cardiac and quercetin glycosides extracted from Dacryodes edulis seeds to reverse vascular and endothelial damage (VAED). Methods The glycoside composition of the seeds was extracted using standard methods and characterized by gas chromatography. We then recruited rats with L-NAME-induced VAED based on confirmatory biomarkers cardiac troponin (CnT), cellular adhesion molecule (VCAM-1), lipoprotein associated phospholipase A2 (Lp-PLA2), RAAS, VWF, endothelin, eNOx, and homocysteine. Only rats that showed total alterations of all biomarkers were recruited into the respective experimental groups and treated with either metaprolol succinate (met.su) + losartan or glycoside extracts of D. edulis seeds (NPSG). Results Chromatographic isolation of glycosides in the seed showed predominance of artemetin (1.59 mg/100 g), amygdalin (3.68 mg/100 g), digitoxin (19.21 mg/100 g), digoxin (27.23 mg/100 g), avicularin (133.59 mg/100 g), and hyperoside (481.76 mg/100 g). We observed decreased water intake and higher heart beats under vascular damage as the experiment progressed up to the fourth week. The met.su + losartan and H.D NPSG proved effective in restoring troponin, but both doses of NPSG normalized the VCAM-1 and RAAS activities excluding aldosterone and Lp-PLA2. Among the endothelial dysfunction biomarkers, H.D NPSG produced equivalent effects to met.su + losartan towards restoring the eNOx and VWF activities, but showed higher potency in normalizing the endothelin and Hcy levels. Conclusions We thus propose that the synergistic effect of the isolated glycosides from D. edulis shown in our study proved potent enough at high doses in treatment of vascular and endothelial dysfunction.

Thrombotic microangiopathy, DIC-syndrome and COVID-19: link with pregnancy prothrombotic state

For last months, humanity has faced a formidable unknown enemy, which is presented as a new coronavirus infection. Despite the fact that the causative agents of new diseases appear at a certain frequency and that the virus SARS-CoV-2 has certain common properties with its predecessors, at the moment we are dealing with a new unknown pathogenesis of the development of severe complications in patients with risk factors. A final understanding of pathological process mechanisms is the goal of the scientific community. Summarizing research data from different countries, it became obvious that in severe cases of viral infection, we are dealing with a combination of the systemic inflammatory response syndrome, disseminated intravascular coagulation and thrombotic microangiopathy (TMA). Thrombotic microangiopathy is represented by a group of different conditions in which thrombocytopenia, hemolytic anemia, and multiple organ failure occur. The article reflects the main types of TMA, pathogenesis and principles of therapy. The main participants in the process are described in detail, including the von Willebrand factor and ADAMTS-13. Based on the knowledge available, as well as new data obtained from patients with COVID-19, we proposed possible models for the implementation of conditions such as sepsis, TMA, and DIC in patients with severe new coronavirus infection. Through a deeper understanding of pathogenesis, it will be possible to develop more effective diagnosis and therapy.

Identification of significant genes in non-small cell lung cancer by bioinformatics analyses

Background

Lung cancer is the most malignant cancer featured with undesirable prognosis. It is urgent to identify novel biomarkers to improve both diagnosis and prognosis. The purpose of the study was to identify significant genes involved in lung cancer through bioinformatic methods and reveal potential underlying mechanisms.

Methods

Three datasets GSE19188, GSE27262, GSE118375, containing 122 lung cancer and 96 normal tissues, were available from GEO database. GEO2R and Venn diagram online software were applied to pick out differentially expressed genes (DEGs). Next, we used the Database for Annotation, Visualization and Integrated Discovery (DAVID) to analyze Kyoto Encyclopedia of Gene and Genome (KEGG) pathway and gene ontology (GO) enrichment, followed by protein-protein interaction (PPI) of these DEGs visualized by cytoscape. The MCODE plug-in was performed to construct a module complex of DEGs. In addition, Kaplan-Meier analysis was implemented for analysis of overall survival. To further validate the expression of these genes, Gene Expression Profiling Interactive Analysis (GEPIA) was used.

Results

A total of 149 DEGs were identified, including 127 downregulated genes and 22 upregulated genes. KEGG analysis revealed that the DEGs were mainly enriched in ECM-receptor interaction, Vascular smooth muscle contraction, and PPAR signaling pathway. GO analysis of DEGs showed that significant functional enrichment of angiogenesis, cell adhesion, and vasculogenesis. 13 genes were selected as hub genes based on MCODE, and 11 of 13 genes had a significance. The results of GEPIA were consistent with survival analysis. Furthermore, reanalysis of these genes found they were significantly enriched in ECM-receptor interaction and PI3K-Akt signaling pathway.

Conclusions

We have identified several key genes, which could be potential diagnostic and prognostic biomarker as well as therapy targets.

Investigating the clearance of VWF A-domains using site-directed PEGylation and novel N-linked glycosylation

BACKGROUND

Previous studies have demonstrated that the A1A2A3 domains of von Willebrand factor (VWF) play a key role in regulating macrophage-mediated clearance in vivo. In particular, the A1-domain has been shown to modulate interaction with macrophage low-density lipoprotein receptor-related protein-1 (LRP1) clearance receptor. Furthermore, N-linked glycans within the A2-domain have been shown to protect VWF against premature LRP1-mediated clearance. Importantly, however, the specific regions within A1A2A3 that enable macrophage binding have not been defined.

OBJECTIVE AND METHODS

To address this, we utilized site-directed PEGylation and introduced novel targeted N-linked glycosylation within A1A2A3-VWF and subsequently examined VWF clearance.

RESULTS

Conjugation with a 40-kDa polyethylene glycol (PEG) moiety significantly extended the half-life of A1A2A3-VWF in VWF-/- mice in a site-specific manner. For example, PEGylation at specific sites within the A1-domain (S1286) and A3-domain (V1803, S1807) attenuated VWF clearance in vivo, compared to wild-type A1A2A3-VWF. Furthermore, PEGylation at these specific sites ablated binding to differentiated THP-1 macrophages and LRP1 cluster II and cluster IV in-vitro. Conversely, PEGylation at other positions (Q1353-A1-domain and M1545-A2-domain) had limited effects on VWF clearance or binding to LRP1.Novel N-linked glycan chains were introduced at N1803 and N1807 in the A3-domain. In contrast to PEGylation at these sites, no significant extension in half-life was observed with these N-glycan variants.

CONCLUSIONS

These novel data demonstrate that site specific PEGylation but not site specific N-glycosylation modifies LRP1-dependent uptake of the A1A2A3-VWF by macrophages. This suggests that PEGylation, within the A1- and A3-domains in particular, may be used to attenuate LRP1-mediated clearance of VWF.

Platelet Transforming Growth Factor-β1 Induces Liver Sinusoidal Endothelial Cells to Secrete Interleukin-6

The roles and interactions of platelets and liver sinusoidal endothelial cells in liver regeneration are unclear, and the trigger that initiates hepatocyte proliferation is unknown. We aimed to identify the key factors released by activated platelets that induce liver sinusoidal endothelial cells to produce interleukin-6 (IL-6), a cytokine implicated in the early phase of liver regeneration. We characterized the releasate of activated platelets inducing the in vitro production of IL-6 by mouse liver sinusoidal endothelial cells and observed that the stimulating factor was a thermolabile protein. Following gel filtration, a single fraction of activated platelet releasate induced a maximal IL-6 secretion by liver sinusoidal endothelial cells (90.2 ± 13.9 versus control with buffer, 9.0 ± 0.8 pg/mL, p < 0.05). Mass spectroscopy analysis of this fraction, followed by in silico processing, resulted in a reduced list of 18 candidates. Several proteins from the list were tested, and only recombinant transforming growth factor β1 (TGF-β1) resulted in an increased IL-6 production up to 242.7 ± 30.5 pg/mL, which was comparable to non-fractionated platelet releasate effect. Using neutralizing anti-TGF-β1 antibody or a TGF-β1 receptor inhibitor, IL-6 production by liver sinusoidal endothelial cells was dramatically reduced. These results support a role of platelet TGF-β1 β1 in the priming phase of liver regeneration.

The development and characterization of a long acting anti-thrombotic von Willebrand factor (VWF) aptamer

BACKGROUND

Thrombus formation involves coagulation proteins and platelets. The latter, referred to as platelet-mediated thrombogenesis, is predominant in arterial circulation. Platelet thrombogenesis follows vascular injury when extracellular von Willebrand factor (VWF) binds via its A3 domain to exposed collagen, and the free VWF A1 domain binds to platelet glycoprotein Ib (GPIb).

OBJECTIVES

To characterize the antiplatelet/antithrombotic activity of the pegylated VWF antagonist aptamer BT200 and identify the aptamer VWF binding site.

METHODS

BT100 is an optimized aptamer synthesized by solid-phase chemistry and pegylated (BT200) by standard conjugation chemistry. The affinity of BT200 for purified human VWF was evaluated as was VWF inhibition in monkey and human plasma. Efficacy of BT200 was assessed in the monkey FeCl3 femoral artery thrombosis model.

RESULTS

BT200 bound human VWF at an EC50 of 5.0 nmol/L and inhibited VWF A1 domain activity in monkey and human plasma with mean IC50 values of 183 and 70 nmol/L. BT200 administration to cynomolgus monkeys caused a time-dependent and dose-dependent effect on VWF A1 domain activity and inhibited platelet function as measured by collagen adenosine diphosphate closure time in the platelet function analyzer. BT200 demonstrated a bioavailability of ≥77% and exhibited a half-life of >100 hours after subcutaneous injection. The treatment effectively prevented arterial occlusion in an FeCl3 -induced thrombosis model in monkeys.

CONCLUSIONS

BT200 has shown promising inhibition of human VWF in vitro and prevented arterial occlusion in non-human primates. These data including a long half-life after subcutaneous injections provide a strong rationale for ongoing clinical development of BT200.

Prognostic value of von Willebrand factor in adult patients with congenital heart disease

OBJECTIVES

von Willebrand factor (vWF) has prognostic value in patients with heart failure (HF) and in those with liver disease. Liver congestion, due to right-sided HF (RHF), is one of the major clinical pathophysiologic manifestations in adults with congenital heart disease (ACHD). The present study's purpose was to clarify the prognostic value of plasma levels of vWF antigen (vWF:Ag) in ACHD.

METHODS

We measured vWF:Ag (%) in 382 consecutive patients (20 unrepaired cyanotic ACHD, 172 Fontan patients and 190 ACHD after biventricular repair) and compared the results with the clinical profiles and prognosis.

RESULTS

The plasma vWF:Ag level was 130±53 (normal range: 55%-190%), and 48 patients (13%) showed high levels of vWF:Ag (≥190%). Older age, Fontan circulation, higher central venous pressure, lower arterial oxygen saturation and lower plasma levels of albumin were independently associated with high log (vWF:Ag) (p<0.05-0.0001). During the follow-up of 2.4±1.4 years, 15 patients died. High log (vWF:Ag) predicted the all-cause mortality (HR 1.63 per 0.1, 95% CI 1.40 to 1.96, p<0.0001). Specifically, patients with high vWF:Ag (≥165%) had a substantially higher risk of all-cause mortality (HR 56.4, 95% CI 11.4 to 1020, p<0.0001), and this prognostic value was independent of plasma levels of brain-type natriuretic peptide.

CONCLUSIONS

High vWF:Ag may reflect RHF severity and related liver dysfunction with a strong prognostic value of all-cause mortality in ACHD. Thus, vWF:Ag might be an excellent biomarker for monitoring ACHD with RHF.

Redox control of vascular biology

Redox control is lost when the antioxidant defense system cannot remove abnormally high concentrations of signaling molecules, such as reactive oxygen species (ROS). Chronically elevated levels of ROS cause oxidative stress that may eventually lead to cancer and cardiovascular and neurodegenerative diseases. In this review, we focus on redox effects in the vascular system. We pay close attention to the subcompartments of the vascular system (endothelium, smooth muscle cell layer) and give an overview of how redox changes influence those different compartments. We also review the core aspects of redox biology, cardiovascular physiology, and pathophysiology. Moreover, the topic-specific knowledgebase DES-RedoxVasc was used to develop two case studies, one focused on endothelial cells and the other on the vascular smooth muscle cells, as a starting point to possibly extend our knowledge of redox control in vascular biology.

Plasmodium-infected erythrocytes induce secretion of IGFBP7 to form type II rosettes and escape phagocytosis

In malaria, rosetting is described as a phenomenon where an infected erythrocyte (IRBC) is attached to uninfected erythrocytes (URBC). In some studies, rosetting has been associated with malaria pathogenesis. Here, we have identified a new type of rosetting. Using a step-by-step approach, we identified IGFBP7, a protein secreted by monocytes in response to parasite stimulation, as a rosette-stimulator for Plasmodium falciparum- and P. vivax-IRBC. IGFBP7-mediated rosette-stimulation was rapid yet reversible. Unlike type I rosetting that involves direct interaction of rosetting ligands on IRBC and receptors on URBC, the IGFBP7-mediated, type II rosetting requires two additional serum factors, namely von Willebrand factor and thrombospondin-1. These two factors interact with IGFBP7 to mediate rosette formation by the IRBC. Importantly, the IGFBP7-induced type II rosetting hampers phagocytosis of IRBC by host phagocytes.

von Willebrand Factor and Management of Heart Valve Disease: JACC Review Topic of the Week

For decades, numerous observations have shown an intimate relationship between von Willebrand factor (VWF) multimer profile and heart valve diseases (HVD). The current knowledge of the unique biophysical properties of VWF helps us to understand the longstanding observations concerning the bleeding complications in patients with severe HVD. Not only does the analysis of the VWF multimer profile provide an excellent evaluation of HVD severity, it is also a strong predictor of clinical events. Also of importance, VWF responds within minutes to any significant change in hemodynamic valve status, making it an accurate marker of the quality of surgical and transcatheter therapeutic interventions. The authors provide in this review a practical, comprehensive, and evidence-based framework of the concept of VWF as a biomarker in HVD, advocating for its implementation into the clinical decision-making process besides usual clinical and imaging evaluation. They also delineate critical knowledge gaps and research priorities to definitely validate this concept.

[Prognostic value of endothelial dysfunction and von Willebrand factor in acute and chronic hemispheric intracerebral hemorrhage]

AIM

To study the changes in endothelial dysfunction and von Willebrand factor activity in acute and chronic stages of hemispheric intracerebral hemorrhage (ICH) and their influence on clinical severity and functional recovery.

MATERIAL AND METHODS

Fifty patients with hemispheric ICH, aged 61.6±11.2 years, and 30 patients with AH, aged 59.6±6.2 years, (comparison group) were examined. Patients with ICH were examined on admission, 6-8^th, 13-15^th days, and 11.1±0.9 months after stroke onset. Patients with arterial hypertension (AH) were examined on admission. Changes in NIHSS, Glasgow coma scale, and modified Rankin scale were studied. Restocetin induced platelet aggregation (RIPA) was assessed by optical aggregometry (BIOLA LA230-2 AGGRWB) in modification by G. Born and Z. Gabbasov. von Willebrand factor (vWF) activity was examined as described by J. Olson.

RESULTS

RIPA was significantly higher in acute ICH compared to chronic ICH, AH and reference values. RIPA values were negatively correlated with hematoma volume and midline shift (r≥ -0.308, p≤0.035). vWF activity was significantly higher in ICH patients than in AH and reference values. Patients with AH also had significantly higher vWF activity than reference values. In acute ICH, vWF activity steadily increased reaching maximal values by 13-15^th day. In chronic ICH, vWF activity decreased compared to the acute phase, but still remained higher than in AH patients or reference values. In acute phase, 1% increment in vWF values resulted in 0.5% increase in the risk of death during the follow-up period (95% CI 1.001-1.008, p=0.007).

CONCLUSION

Endothelial dysfunction assessed by vWF activity increases during the acute hemispheric ICH and remains elevated in the chronic stage. vWF activity may be used as a marker in assessing stroke outcome and prognosis.

Bleeding in critical care associated with left ventricular assist devices: pathophysiology, symptoms, and management

Chronic heart failure (HF) is a growing health problem, and it is associated with high morbidity and mortality. Left ventricular assist devices (LVADs) are nowadays an important treatment option for patients with end-stage HF not only as a bridging tool to heart transplantation but also, as a permanent therapy for end-stage HF (destination therapy). The use of LVAD is associated with a high risk for bleeding complications and thromboembolic events, including pump thrombosis and ischemic stroke. Bleeding is the most frequent complication, occurring in 30% to 60% of patients, both early and late after LVAD implantation. Although the design of LVADs has improved over time, bleeding complications are still the most common complication and occur very frequently. The introduction of an LVAD results in an altered hemostatic balance as a consequence of blood-pump interactions, changes in hemodynamics, acquired coagulation abnormalities, and the strict need for long-term anticoagulant treatment with oral anticoagulants and antiplatelet therapy. LVAD patients may experience an acquired coagulopathy, including platelet dysfunction and impaired von Willebrand factor activity, resulting in acquired von Willebrand syndrome. In this educational manuscript, the epidemiology, etiology, and pathophysiology of bleeding in patients with LVAD will be discussed. Because hematologist are frequently consulted in cases of bleeding problems in these individuals in a critical care setting, the observed type of bleeding complications and management strategies to treat bleeding are also reviewed.

Mechanochemistry of von Willebrand factor

Von Willebrand factor (VWF), a blood multimeric protein with a very high molecular weight, plays a crucial role in the primary haemostasis, the physiological process characterized by the adhesion of blood platelets to the injured vessel wall. Hydrodynamic forces are responsible for extensive conformational transitions in the VWF multimers that change their structure from a globular form to a stretched linear conformation. This feature makes this protein particularly prone to be investigated by mechanochemistry, the branch of the biophysical chemistry devoted to investigating the effects of shear forces on protein conformation. This review describes the structural elements of the VWF molecule involved in the biochemical response to shear forces. The stretched VWF conformation favors the interaction with the platelet GpIb and at the same time with ADAMTS-13, the zinc-protease that cleaves VWF in the A2 domain, limiting its prothrombotic capacity. The shear-induced conformational transitions favor also a process of self-aggregation, responsible for the formation of a spider-web like network, particularly efficient in the trapping process of flowing platelets. The investigation of the biophysical effects of shear forces on VWF conformation contributes to unraveling the molecular mechanisms of many types of thrombotic and haemorrhagic syndromes.

Characterization of the mutation spectrum in a Pakistani cohort of type 3 von Willebrand disease

INTRODUCTION

Type 3 von Willebrand disease (VWD), a severe autosomal recessive hereditary bleeding disorder, is described by the virtual absence of von Willebrand factor (VWF). In consanguineous populations, for example Pakistan, the disease is reported with a higher incidence rate than the worldwide prevalence.

AIMS

This study aims to characterize molecular pathology and clinical profile of type 3 VWD cohort of Pakistani origin.

METHODS

In total, 48 patients were enrolled in the current study. Initially, the index patients (IPs) were evaluated by a standardized questionnaire for recording bleeding manifestations and by performing conventional coagulation tests. The diagnosis of VWD type 3 was confirmed by VWF antigens less than 5 IU/dL. Direct sequencing of VWF gene (VWF) was carried out to identify causative gene variations. We evaluated the potential consequence of novel splice site and missense variations by predictive computational programs and in silico structural analysis.

RESULTS

VWF mutations were detected in 46 out of 48 IPs (95.8%), predominantly as homozygous variants. In total, twenty-nine different gene defects were characterized in this cohort from which 10 (34.5%) are novel. The majority of the mutations were null alleles (66%; including gene conversions, nonsense, splice site variations, small deletions and insertions), and 34% of them were missense substitutions.

CONCLUSION

Herein, we reported for the first time, the pattern of gene defects in Pakistani type 3 VWD cohort. We identified a wide heterogeneous mutation spectrum along with variability in the type of bleeding episodes.

Clinical and In Vitro Evidence That Left Ventricular Assist Device-Induced von Willebrand Factor Degradation Alters Angiogenesis

Background Gastrointestinal bleeding from angiodysplasia is a major problem in continuous-flow left ventricular assist device (LVAD) patients. LVAD shear stress causes pathologic degradation of VWF (von Willebrand factor). A mechanistic relationship between VWF degradation and angiodysplasia has not been explored. We tested 2 novel hypotheses: (1) clinical hypothesis: VWF fragments are elevated in LVAD patients that develop angiodysplasia and (2) in vitro hypothesis: VWF fragments generated during LVAD support alter angiogenesis, which may contribute to angiodysplasia. Methods and Results Clinical study: Paired blood samples were collected from continuous-flow LVAD patients (n=35). VWF was quantified with immunoblotting. In vitro experiments: (1) To investigate whether LVAD support alters angiogenesis, human endothelial cells were cultured with LVAD patient plasma (n=11). To investigate mechanism, endothelial cells were cultured with VWF fragments produced by exposing human VWF and ADAMTS-13 (VWF protease) to LVAD-like shear stress (175 dyne/cm², n=8). Clinical study results: in all patients (n=35, mean support 666±430 days), LVAD support degraded high-molecular-weight VWF multimers ( P<0.0001) into low-molecular-weight VWF multimers ( P<0.0001) and VWF fragments ( P<0.0001). In patients with gastrointestinal bleeding from angiodysplasia (n=7), VWF fragments were elevated ( P=0.02) versus nonbleeders. In contrast, in patients with gastrointestinal bleeding without angiodysplasia, VWF fragments were not elevated versus nonbleeders ( P=0.96). In vitro experiments results: LVAD patient plasma caused abnormal angiogenesis with reduced tubule length ( P=0.04) and migration ( P=0.05). Similarly, endothelial cells grown with VWF degradation fragments exhibited reduced tubule length ( P<0.001) and migration ( P=0.01). Conclusions LVAD patients who bled from angiodysplasia had higher levels of VWF fragments than nonbleeders and gastrointestinal bleeders without angiodysplasia. VWF fragments caused abnormal angiogenesis in vitro. These findings suggest that VWF fragments may be a mechanistic link between LVAD support, abnormal angiogenesis, angiodysplasia, and gastrointestinal bleeding.

Impact of capacity-limited binding on recombinant factor VIII and von Willebrand factor pharmacokinetics in hemophilia A rats

Essentials Knowledge of the interplay between FVIII and VWF pharmacokinetics (PK) is lacking. We characterized the capacity-limited PK of FVIII and VWF. The PK model described the PK of FVIII and VWF over a broad range of rFVIII doses. High-dose rFVIII treatment can reduce the endogenous VWF levels.

BACKGROUND

Understanding of the pharmacokinetics (PK) interplay between factor VIII (FVIII) and von Willebrand factor (VWF) following high-dose FVIII treatment is lacking.

OBJECTIVES

To characterize the PK of recombinant FVIII (rFVIII), VWF, and the rFVIII:VWF complex in hemophilia A rats following intravenous administration of rFVIII using PK modeling. A second aim was to investigate the effect of high daily dosing and constant expression of rFVIII on VWF exposure using PK simulations.

METHODS

We developed a population PK model based on the principles of target-mediated drug disposition modeling, using data on total rFVIII and VWF plasma concentrations, and the rFVIII:VWF complex luminescent oxygen channeling immunoassay signal in hemophilia A rats following intravenous administration of rFVIII (17.5, 100, 1000, and 5000 IU kg-1 ). Additionally, we evaluated the influence of high-dose rFVIII treatment on the exposure of VWF using PK simulations.

RESULTS

The plasma concentration-time profiles of total rFVIII and VWF, and the luminescent oxygen channeling immunoassay signal-time profiles of the rFVIII:VWF complex were adequately described using a two-compartment quasi-steady-state target-mediated drug disposition model (Kss  = 0.14 nmol L-1 ). The elimination half-life of the rFVIII:VWF complex was dependent on the unbound plasma concentration of rFVIII. Additionally, we showed that high-dose rFVIII treatment may significantly reduce the endogenous VWF levels.

CONCLUSIONS

We developed a population-based PK model describing the time-course of total rFVIII, total VWF, and the rFVIII:VWF complex over a broad range of rFVIII doses in hemophilia A rats.

Heyde Syndrome: Aortic Stenosis and Beyond

Heyde described aortic stenosis and gastrointestinal bleeding in the 1950s. Since then, a link with intestinal angiodysplasia and abnormalities of von Willebrand factor (VWF) has been noted. Loss of the highest-molecular-weight multimers of VWF and bleeding also have been described in subaortic stenosis in hypertrophic cardiomyopathy, in isolated mitral and aortic insufficiency, in endocarditis, in patients with prosthetic valve stenosis or regurgitation, and in patients with left ventricular assist devices (LVADs). Bleeding tends to recur with local treatment of angiodysplasias, whereas cardiac repair or removal of LVAD eliminates VWF dysfunction is curative of bleeding in the majority.

ADAMTS13 and von Willebrand factor are useful biomarkers for sorafenib treatment efficiency in patients with hepatocellular carcinoma

BACKGROUND

Many advanced hepatocellular carcinoma (HCC) patients are receiving sorafenib treatment. Sorafenib reportedly improves overall survival (OS) significantly in patients with HCC. Prediction of sorafenib response and prognosis in patients with HCC receiving sorafenib treatment are important due to the potentially serious side effects of sorafenib. A disintegrin-like and metalloproteinase with thrombospondin type-1 motifs 13 (ADAMTS13) and von Willebrand factor (VWF) are associated with the pathophysiology of liver cirrhosis and HCC through their roles in hypercoagulability; they are also associated with angiogenesis via vascular endothelial growth factor (VEGF). The imbalance between ADAMTS13 and VWF was associated with prognosis of various cancers in patients undergoing chemotherapy.

AIM

To investigate ADAMTS13 and VWF as potential biomarkers for sorafenib response and prognosis in patients with HCC receiving sorafenib treatment.

METHODS

Forty-one patients with HCC receiving sorafenib treatment were included in this study. The initial daily sorafenib dose was 400 mg in all patients. ADAMTS13 activity (ADAMTS13:AC), VWF antigen (VWF:Ag), VEGF levels were determined by enzyme-linked immunosorbent assay. Univariate and multivariate analyses were used to determine predictive factors for sorafenib response and prognosis in patients with HCC receiving sorafenib treatment.

RESULTS

ADAMTS13:AC was significantly higher in patients with stable disease (SD), partial response (PR), and complete response (CR) than in those with progressive disease (PD) (P < 0.05). In contrast, VWF:Ag and the VWF:Ag/ADAMTS13:AC ratio were significantly lower in patients with SD, PR, and CR than in those with PD (P < 0.05 for both). Multivariate analysis showed that the VWF:Ag/ADAMTS13:AC ratio was the only predictive factor for sorafenib response and ADAMTS13:AC was the only prognostic factor in patients with HCC receiving sorafenib treatment. The patients with a low ADAMTS13:AC (< 78.0) had significantly higher VEGF levels than those with a high ADAMTS13:AC (≥ 78.0) (P < 0.05).

CONCLUSION

The VWF:Ag/ADAMTS13:AC ratio and ADAMTS13:AC are potentially useful biomarkers for sorafenib response and prognosis, respectively, in patients with HCC receiving sorafenib treatment.

Sleep characteristics and inflammatory biomarkers among midlife women

Study Objectives

Research suggests that sleep disturbances are associated with elevated levels of inflammation. Some evidence indicates that women may be particularly vulnerable; increased levels of inflammatory biomarkers with sleep disturbances are primarily observed among women. Midlife, which encompasses the menopause transition, is typically reported as a time of poor sleep. We tested whether poorer objectively measured sleep characteristics were related to a poorer inflammatory profile in midlife women.

Methods

Two hundred ninety-five peri- and postmenopausal women aged 40-60 completed 3 days of wrist actigraphy, physiologic hot flash monitoring, questionnaires (e.g. Berlin sleep apnea risk questionnaire], and a blood draw for the assessment of inflammatory markers, including C-reactive protein (CRP), interleukin-6 (IL-6), and von Willebrand factor (VWF) antigen. Associations of objective (actigraphy) sleep with inflammatory markers were tested in regression models. Sleep efficiency was inverse log transformed. Covariates included age, race/ethnicity, education, body mass index, sleep apnea risk, homeostatic model assessment (a measure of insulin resistance), systolic blood pressure, low-density lipoprotein cholesterol, and physical activity.

Results

In separate models controlling for age, race/ethnicity, and education, lower sleep efficiency was associated with higher IL-6 [b(SE) = .02 (.10), p = .003] and VWF [b(SE) = .02 (.08), p = .002]. More minutes awake after sleep onset was associated with higher VWF [b(SE) = .12 (.06), p = .01]. Findings persisted in multivariable models.

Conclusions

Lower sleep efficiency and more minutes awake after sleep onset were independently associated with higher circulating levels of VWF. Lower sleep efficiency was associated with higher circulating levels of IL-6. These findings suggest that sleep disturbances are associated with greater circulating inflammation in midlife women.

Vascular endothelial growth factor (VEGF), transforming growth factor beta (TGFβ), angiostatin, and endostatin are increased in radiotherapy-induced gastrointestinal toxicity

PURPOSE

Radiotherapy-induced gut toxicity (RIGT) is a debilitating effect of radiotherapy for cancer, often resulting in significant diarrhea and pain. Previous studies have highlighted roles of the intestinal microvasculature and matrix metalloproteinases (MMPs) in the development of RIGT. We hypothesized vascular mediators would be significantly altered in a dark agouti (DA) rat model of RIGT. Additionally, we aimed to assess the effect of MMP-2 and -9 inhibition on the response of tumor-associated microvascular endothelial cells (TAMECs) to radiation.

METHODS

DA rats were administered 2.5 Gy abdominal irradiation (3 times/week over 6 weeks). Vascular endothelial growth factor (VEGF), transforming growth factor beta (TGFβ), von Willebrand factor (VWF), angiostatin, and endostatin expression was assessed at 3, 6, and 15 weeks. Additionally, DA rat mammary adenocarcinoma tumor-associated microvascular endothelial cells (TAMECs) were used to assess the effects of radiation (12 Gy) and the MMP inhibitor SB-3CT on MMP, VEGF, and TGFβ expression, and cell viability.

RESULTS

VEGF mRNA expression was significantly increased in the colon at week 15 (p = .0012), and TGFβ mRNA expression was significantly increased in both the jejunum and colon at week 3 (p = .0280 and p = .0310, respectively). Endostatin immunostaining was significantly increased at week 3 (p = .0046), and angiostatin at 3 and 6 weeks (p = .0022 and p = .0135, respectively). MMP-2 and -9 mRNA and total protein levels were significantly increased following irradiation of TAMECs. Although this increase was significantly attenuated by SB-3CT, it did not significantly alter endothelial cell viability or VEGF and TGFβ mRNA expression.

CONCLUSIONS

Findings of this study support the involvement of VEGF, TGFβ, angiostatin, endostatin, and MMP-2 in the pathobiology of RIGT. However, the relationship between these mediators is complex and needs further investigation to improve understanding of their therapeutic potential in RIGT.

Blood inflammatory and endothelial markers in women with von Willebrand disease

Introduction

VWD-affected females often experience menorrhagia. Periodical fluctuations of the sex steroids during the menstrual cycle cause changes both in the coagulation and immune system. The aim of the current study was to assess the changes in selected inflammatory and endothelial markers in women with VWD during two phases of the menstrual cycle (follicular and luteal) and to compare it with corresponding data from healthy controls.

Materials and methods

The study group included 12 VWD-affected females with regular menstrual cycle, with none of them being prescribed hormone treatment. They were not pregnant or breastfeeding. The control group consisted of 102 healthy females, matched for age and BMI.

Results

Within the VWD group, endostatin was higher during the follicular phase, compared to the luteal phase, although the difference was not significant (p = 0.062). sICAM-1 and IL-6 were higher in VWD-affected females, compared to the controls, sVCAM-1, cathepsin S and sP-selectin were lower (p<0.003 for all cases). The pattern was constant throughout the menstrual cycle.

Conclusions

Higher levels of endostatin during early follicular phase could potentially predispose women with VWD to the development of heavy menstrual bleeding, due to antiangiogenic properties and ability to suppress several coagulation factors. Lower p-selectin levels in VWD group, compared to controls, may also contribute to the bleeding tendency. Changes in other proteins, involved in angiogenesis are hypothetically related to the formation of angiodysplasia—common complication of VWF deficiency. The latter statement requires confirmation in larger studies.

Investigation of aspects of the interaction of the indicators of lipid exchange, trombocitarian block of hemostasis, total body reactivity and their influence on the psychosomatic harmonization of the man in chronic inflammatory processes

For the first time on the basis of clinical and laboratory researches were revealed the correlation of indicators of lipid metabolism, platelet level of hemostasis and general reactivity in patients with chronic inflammatory processes of the genital system. The new pathogenetic aspects of the course of inflammatory diseases have been established. It has been shown that chronic inflammatory process is accompanied by disorders of lipid metabolism. The degree of severity of these changes depends on the severity of the inflammatory process, the reduction of phagocytic activity of polymorphonuclear leukocytes and the activation of macrophage and specific cellular mechanisms, accompanied by auto-intoxication. It is established that the frequency of atherogenic dyslipoproteinemias, as well as the intensity of lipid peroxidation increases in accordance with the increase age of the examined patients. Most atherogenic dyslipoproteinemias are found in patients with viral and chlamydial infections. The summarized data of the correlation analysis allow us to establish that the growth of atherogenic properties of blood plasma of patients with chronic inflammatory processes of the reproductive system occurs in accordance with the increase of adhesive-aggregation properties of platelets and damage of the vascular endothelium. These shifts occur in parallel with the predominance of the monocyte-macrophage linkage of phagocytosis against the background of reduced activity of neutrophils and cellular mechanisms of development of immunopathological reactions.

von Willebrand factor is a useful biomarker for liver fibrosis and prediction of hepatocellular carcinoma development in patients with hepatitis B and C

BACKGROUND

Several noninvasive biomarkers are available for diagnosing liver fibrosis stage and predicting hepatocellular carcinoma (HCC) development in patients with chronic hepatitis and liver cirrhosis. However, these biomarkers are not sufficiently accurate. Recently, von Willebrand factor (VWF) has been related to angiogenesis and apoptosis. Furthermore, VWF is associated with hepatic spare ability and HCC.

OBJECTIVE

We aimed to determine whether VWF is a potential biomarker for liver fibrosis and HCC development.

METHODS

Two hundred and twelve patients with chronic hepatitis B and C were recruited. VWF antigen (VWF: Ag) levels in each patient were determined via enzyme-linked immunosorbent assay. Univariable and multivariable analyses were used to determine the risk factor of HCC.

RESULTS

The VWF: Ag levels were higher in patients with severe liver fibrosis stage and/or HCC development than in those without. The area under the curve of VWF: Ag for diagnosis of severe liver fibrosis stage was 0.721. Multivariable analysis showed that only VWF: Ag was a predictive biomarker for HCC development.

CONCLUSIONS

VWF: Ag is related to liver fibrosis and may be useful for predicting HCC development. VWF is a potentially useful biomarker to diagnose severe liver fibrosis and predict HCC development.

Von Willebrand factor contribution to pathophysiology outside of von Willebrand disease

VWF is a procoagulant protein that plays a central role in the initiation of platelets aggregate formation and thrombosis. While von Willebrand disease has long been known to result from qualitative and quantitative deficiencies of VWF, it is recently that contribution of elevated levels of VWF to various pathological conditions including thrombosis, inflammation, angiogenesis, and cancer metastasis has been appreciated. Here, we discuss contribution of elevated levels of VWF to various thrombotic and nonthrombotic pathological conditions.

Recent Advances in Endothelial Colony Forming Cells Toward Their Use in Clinical Translation

The term “Endothelial progenitor cell” (EPC) has been used to describe multiple cell populations that express endothelial surface makers and promote vascularisation. However, the only population that has all the characteristics of a real “EPC” is the Endothelial Colony Forming Cells (ECFC). ECFC possess clonal proliferative potential, display endothelial and not myeloid cell surface markers, and exhibit pronounced postnatal vascularisation ability in vivo. ECFC have been used to investigate endothelial molecular dysfunction in several diseases, as they give access to endothelial cells from patients in a non-invasive way. ECFC also represent a promising tool for revascularization of damaged tissue. Here we review the translational applications of ECFC research. We discuss studies which have used ECFC to investigate molecular endothelial abnormalities in several diseases and review the evidence supporting the use of ECFC for autologous cell therapy, gene therapy and tissue regeneration. Finally, we discuss ways to improve the therapeutic efficacy of ECFC in clinical applications, as well as the challenges that must be overcome to use ECFC in clinical trials for regenerative approaches.

A predictive value of von Willebrand factor for early response to Bevacizumab therapy in recurrent glioma

Bevacizumab (BV), a neutralizing monoclonal antibody against the vascular endothelial growth factor ligand, is recognized as a potent anti-angiogenic agent with antitumor activity. The aim of this single-center, retrospective, longitudinal study was to investigate the possible predictive value of baseline demographic, clinical and laboratory parameters for early 3-month response to BV therapy in patients with recurrent glioma. Forty-nine patients with recurrent glioma received BV at 10 mg/kg intravenously every 3 weeks alone or in association with chemotherapy were included in this study. Blood samples were collected from all patients before the first (baseline), the second and the third administration of BV. After 3 months of BV therapy, patients with partial response were defined as responders whereas patients with stable or progressive disease were defined as non-responders. The median overall follow-up was 8 months (range 1-73), the median overall survival (OS) was 8 months (95% CI 6-10) and the median progression free survival (PFS) was 4 months (95% CI 3-5). Thirty-five % of patients were responders and showed significantly lower von Willebrand factor (VWF) levels than non-responders at all sample times (p < .02 for all). Also, on multivariate analysis the baseline VWF value was the only predictor for an early response to BV therapy. Furthermore, D-dimer and prothrombin fragment 1+2 were predictive factors for OS while Karnofsky performance status resulted predictive for PFS. VWF antigen value is a possible predictive biomarker for an early 3-month response to BV therapy in recurrent glioma.

Low dose cadmium upregulates the expression of von Willebrand factor in endothelial cells

Cadmium (Cd) is a persistent and widespread environmental pollutant of continuing worldwide concern. Previous studies have suggested that Cd exposure increases the risk of cardiovascular diseases, such as atherosclerosis and hypertension. However, the underlying mechanisms are poorly understood. In this study, we observed that low dose Cd treatment induced von Willebrand factor (vWF) expression in vascular endothelial cells in mouse lung and kidney tissues. In vitro analysis showed that 1 μM Cd specifically upregulated vWF mRNA and protein expression in human umbilical vein endothelial cells (HUVECs), indicating that Cd targets vascular endothelial cells even at relatively low concentrations. Further study demonstrated that nuclear factor kappa B (NF-κB) and GATA3, two established transcription regulators of the vWF gene, were not altered in the presence of Cd. However, ETS-related gene (ERG) was significantly induced by 1 μM Cd. When ERG was knocked down by siRNA, Cd induced upregulation of vWF was totally blocked. Chromatin immunoprecipitation (ChIP) assay showed that Cd increases the binding of ERG on the -56 ETS motif on the human vWF promoter. These results indicated that ERG mediated the increased expression of vWF by Cd. Since vWF is a key regulator for vascular homeostasis, our findings may provide a novel mechanism for understanding low dose Cd induced development of vascular diseases.

Acquired coagulopathy in patients with left ventricular assist devices

Chronic heart failure (HF) is a major emerging healthcare problem, associated with a high morbidity and mortality. Left ventricular assist devices (LVADs) have emerged as a successful treatment option for patients with end-stage HF. Despite its great benefit, the use of LVAD is associated with a high risk of complications. Bleeding, pump thrombosis and thromboembolic events are frequently observed complications, with bleeding complications occurring in over a third of the patients. Although the design of the third-generation LVAD has improved greatly, these hemostatic complications still occur. The introduction of an LVAD into the circulatory system results in an altered hematological balance as a consequence of blood-pump interactions, changes in hemodynamics, the rheology, and the concomitant need for anticoagulation while implanted with an LVAD. The majority, if not all, LVAD patients experience a form of platelet dysfunction and impaired von Willebrand factor activity, leading to acquired coagulopathy disorders. Different diagnostic tools and treatment strategies have been reported; however, they require validation in LVAD patients. The present review focuses on acquired coagulopathies, describing the incidence, impact and underlying mechanism of acquired coagulopathy disorders in patients supported by LVADs. In addition, we will discuss diagnostic and management strategies for these acquired coagulopathies.

Lenalidomide as a novel therapy for gastrointestinal angiodysplasia in von Willebrand disease

INTRODUCTION

Lenalidomide is a thalidomide analog with anti-angiogenic properties. Previous case reports suggest its efficacy in preventing gastrointestinal bleeding (GIB) secondary to angiodysplasia (AD) in hereditary haemorrhagic telangiectasia and potentially in reversing AD. We present the first case series to explore lenalidomide as a treatment for AD-related GIB in patients with von Willebrand disease (VWD).

METHODS

A retrospective chart review was conducted to include patients with VWD, who were evaluated from 2010 to 2013 and who had received lenalidomide to treat recurrent GIB secondary to AD. All patients had failed single-agent use of antifibrinolytic agents. Patients were observed for at least 2 years on therapy.

RESULTS

Five patients (3 males; 68.2 ± 4.9 years) with VWD (3 with type 3 and 1 each with types 1 and 2a) and AD were found. Sites of AD included the stomach, duodenum, jejunum and colon. Lenalidomide was started at 5 mg oral daily. Uptitration to 10 and 15 mg in 1 patient each was necessary due to recurrence of GIB. The mean number of endoscopies performed for control of GIB post lenalidomide was significantly lower compared to pretherapy (0.25 vs 5.50; P = .001). Mean bleed-free duration on lenalidomide was 12.6 ± 4.7 months. Three patients have reported no GIB on lenalidomide.

CONCLUSION

This case series demonstrates significantly reduced number of endoscopies and increased bleed-free duration with lenalidomide treatment in selected patients with VWD and recurrent GIB from AD. Prospective multicenter trials are needed to further define the role of lenalidomide in the management of GIB from angiodysplasia and VWD.

Gastrointestinal Bleeding in Native and Prosthetic Valve Disease

Gastrointestinal bleeding with severe aortic stenosis was originally described in the 1950s by Heyde, although for years, the association was debated. Further discovery of mechanisms and the ubiquity and severity of acquired von Willebrand syndrome in the left ventricular assist device therapy have removed any doubts. At this time, gastrointestinal bleeding from intestinal angiodysplasia in patients with turbulence-related proteolysis of the highest molecular weight multimers of von Willebrand factor is now known to occur in patients with aortic stenosis, and also subaortic obstruction and associated mitral insufficiency in hypertrophic cardiomyopathy, isolated mitral and aortic insufficiency, endocarditis, and in patients with prosthetic valve dysfunction, either from stenosis or insufficiency. The degree of loss of high molecular weight multimers correlates with lesion severity, and tests of von Willebrand factor function have been proposed as important biomarkers of the severity of valve dysfunction, including in-lab testing for paravalvular leak during transcatheter aortic valve replacement. Bleeding tends to recur after endoscopic or surgical therapy, but cardiac repair is curative in the great majority.

Von Willebrand Factor as a Novel Player in Valvular Heart Disease: From Bench to Valve Replacement

von Willebrand Factor (vWF) is a well-known mediator of hemostasis and vascular inflammation. Its dynamic modulation in the bloodstream, according to hemodynamic conditions, makes it an appealing biomarker in patients with valvular heart disease (VHD). Recent studies highlight the close connection between vWF and VHD, with possible implications in the pathogenesis of VHD, promoting valve aging and calcification or favoring the development of infective endocarditis. Moreover, vWF has been recently proposed as a new diagnostic and prognostic tool in patients with valve stenosis or regurgitation, showing a strict correlation with severity of valve disease, outcome, and bleeding (Heyde syndrome). A novel role for vWF is also emerging in patients undergoing percutaneous or surgical valve repair/replacement to select and stratify patients, evaluate periprocedural bleeding risk, and detect procedural complications. We also report our single-center experience, suggesting, for the first time, possible clinical implications for vWF in percutaneous mitral valve repair (MitraClip). This review summarizes recent advances in the role of vWF in VHD with an updated overview going from bench to operating room.

Review of biomarkers to assess the effects of switching from cigarettes to modified risk tobacco products

Context: One approach to reducing the harm caused by cigarette smoking, at both individual and population level, is to develop, assess and commercialize modified risk alternatives that adult smokers can switch to. Studies to demonstrate the exposure and risk reduction potential of such products generally involve the measuring of biomarkers, of both exposure and effect, sampled in various biological matrices.Objective: In this review, we detail the pros and cons for using several biomarkers as indicators of effects of changing from conventional cigarettes to modified risk products.Materials and methods: English language publications between 2008 and 2017 were retrieved from PubMed using the same search criteria for each of the 25 assessed biomarkers. Nine exclusion criteria were applied to exclude non-relevant publications.Results: A total of 8876 articles were retrieved (of which 7476 were excluded according to the exclusion criteria). The literature indicates that not all assessed biomarkers return to baseline levels following smoking cessation during the study periods but that nine had potential for use in medium to long-term studies.Discussion and conclusion: In clinical studies, it is important to choose biomarkers that show the biological effect of cessation within the duration of the study.

GATA3-induced vWF upregulation in the lung adenocarcinoma vasculature

Lung adenocarcinoma (LAC) is the leading cause of cancer-related death worldwide. Aberrant expression of genes expressed preferentially in the lung tumor vasculature may yield clues for prognosis and treatment. Von Willebrand factor (vWF) is a large multifunctional glycoprotein with a well-known function in hemostasis. However, vWF has been reported to exert an anti-tumor effect, independent of its role in hemostasis. We investigated the expression of vWF in LAC through immunohistochemical staining of tumor tissue microarrays (TMAs). We found that vWF was overexpressed preferentially in the tumor vasculature of LAC compared with the adjacent tissue vasculature. Consistently, elevated vWF expression was found in endothelial cells (ECs) of fresh human LAC tissues and transplanted mouse LAC tissues. To understand the mechanism underlying vWF up-regulation in LAC vessels, we established a co-culture system. In this system, conditioned media (CM) collected from A549 cells increased vWF expression in human umbilical vein endothelial cells (HUVECs), suggesting enhanced expression is regulated by the LAC secretome. Subsequent studies revealed that the transcription factor GATA3, but not ERG, a known regulator of vWF transcription in vascular cells, mediated the vWF elevation. Chromatin immunoprecipitation (ChIP) assays validated that GATA3 binds directly to the +220 GATA binding motif on the human vWF promoter and A549 conditioned media significantly increases the binding of GATA3. Taken together, we demonstrate that vWF expression in ECs of LAC is elevated by the cancer cell-derived secretome through enhanced GATA3-mediated transcription.

Current advances in circulating inflammatory biomarkers in atherosclerosis and related cardio-cerebrovascular diseases

Atherosclerosis (AS) is a systemic chronic disease affecting both the coronary and cerebral arteries. Inflammation plays a key role in the initiation and progression of AS, and numerous inflammatory factors have been proposed as potential biomarkers. This article reviews recent research in studies on major circulating inflammatory biomarkers to identify surrogates that may reflect processes associated with AS development and the risk of AS-related vascular events, such as Von Willebrand factor, lectin-like oxidized low-density-lipoprotein receptor-1, soluble urokinase plasminogen activator receptor, regulated upon activation, normal T-cell expressed and secreted, and microparticles, which may provide new perspectives for clinical AS evaluation and risk stratification.

Gastrointestinal angiodysplasia and bleeding in von Willebrand disease

Von Willebrand disease (VWD), the most common genetic bleeding disorder, is characterised by a quantitative or qualitative defect of von Willebrand factor (VWF). Patients with VWD suffer from mucocutaneous bleeding, of severity usually proportional to the degree of VWF defect. In particular, gastrointestinal bleeding associated with angiodysplasia is often a severe symptom of difficult management. This review focuses on the pathophysiology, diagnosis and treatment of VWD-associated gastrointestinal angiodysplasia and related bleeding.

Persistent Gastrointestinal Angiodysplasia in Heyde's Syndrome after Aortic Valve Replacement

A 67-year-old woman with recurrent gastrointestinal bleeding and aortic valve stenosis presented with spurting bleeding from angiodysplasia of the upper jejunum. As electrophoresis revealed decreased levels of high-molecular-weight (HMW) von Willebrand factor (VWF) multimers, she was diagnosed with Heyde's syndrome. After aortic valve replacement, her HMW VWF levels quickly recovered to normal, and the gastrointestinal bleeding ceased. However, capsule endoscopy still revealed gastrointestinal angiodysplasia six months later. This case shows that minute analyses of VWF multimers enable the diagnosis and confirmation of the resolution of Heyde's syndrome, and implies that gastrointestinal angiodysplasia can be attributed to unknown factors other than decreased VWF multimers.