Mechanisms in Experimental Venous Valve Failure and their Modification by Daflon© 500 mg

Reduction of lower-limb edema in patients with chronic venous disease by micronized purified flavonoid fraction: a systematic literature review and meta-analysis

INTRODUCTION

The prevalence of lower limb edema is high among patients with chronic venous disease (CVD). Several clinical studies with various designs have assessed the effect of micronized purified flavonoid fraction (MPFF) on edema. The aim of this work was to provide a comprehensive and accurate evaluation of the reduction in ankle and calf circumference as an indicator of lower limb edema reduction in patients with CVD treated with MPFF by combining studies that use different designs in a single group meta-analysis.

EVIDENCE ACQUISITION

We conducted a systematic literature review in April 2022 based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) criteria to identify prospective studies investigating the effect of oral MPFF treatment 1000 mg/day on ankle and calf circumference in patients with CVD. Studies with population including at least one patient with an ulcer were excluded. All prospective studies irrespectively of design (i.e., interventional and non-interventional studies, randomized controlled trials (RCTs), non-randomized studies, studies without a control or reference treatment) were eligible. The Medline, Embase and Cochrane databases were searched. Endpoints were ankle and calf circumference measurements and their overall mean change from baseline estimated with random-effects meta-analysis methods. The evaluation criterion feeling of swelling was also analyzed as a standardized mean change (SMC) with 95% confidence intervals after combination of quantitative scales.

EVIDENCE SYNTHESIS

Among 861 articles identified, eight studies (five RCTs including one placebo-controlled, three non-comparative studies) met the criteria. The overall population consisted of 1635 patients, predominantly female (89% ranging from 64% to 94%) with a mean age of 47 years ranging from 41 to 48 years. Mean reduction in ankle circumference was 6.0 mm (95%CI: 3.6 to 8.4; P<0.001) and 7.0 mm (95%CI: 0.9 to 13.1; P=0.024) after two and at least six months of treatment respectively. The results were similar when considering the study type RCTs and non-RCTs. Mean reduction in calf circumference was 5.7 mm (95%CI: 2.8 to 8.6; P<0.001) and 6.7 mm (95%CI: 5.2 to 8.1; P<0.001), at two months and at the last post-baseline evaluation respectively. Heterogeneity among studies was statistically significant (degree of consistency I2=93.5%; P<0.001 and I2=81.1%, P<0.01 for ankle and calf circumference, respectively). In the three studies reporting the effect on feeling of swelling a significant standardized mean change (SMC) reduction of 2.2 (95%CI: 0.2 to 4.2; P=0.028) on a quantitative scale was observed after two months of treatment with MPFF.

CONCLUSIONS

MPFF appeared to be effective in reducing ankle and calf circumference as well as feeling of swelling irrespective of study design. The circumference reduction is present at short and long term, suggesting that benefit occurs early and is maintained overtime. Despite the observed heterogeneity among included studies, this meta-analysis supports the significant therapeutic efficacy of MPFF in reducing lower-limb edema in patients with CVD. The complete video presentation of the work is available online at www.minervamedica.it (Supplementary Digital Material 1: Supplementary Video 1, 5 min, 192 MB).

Improving Chronic Venous Disease Management with Micronised Purified Flavonoid Fraction: New Evidence from Clinical Trials to Real Life

Chronic venous disease (CVD) develops in the microvessels, and is perpetuated by a vicious cycle of inflammation and endothelial activation, structural and functional changes to vessels and valves, and progressive venous hypertension. Data from animal models indicate that micronised purified flavonoid fraction (MPFF) has beneficial effects on a range of pathophysiological processes that contribute to CVD, including inflammation, micro-vessel permeability, valve and vessel wall remodelling, and reflux in microvalves. These effects explain its beneficial effects on the signs and symptoms of CVD, which have been seen across the spectrum of Clinical, Etiological, Anatomical and Pathophysiological (CEAP) categories of CVD severity. This includes patients with symptoms but no detectable anatomical or pathophysiological anomalies (C0s or C1) and patients with varicose veins (C2). In addition to symptomatic improvement, MPFF has been shown to reduce oedema in patients with C3 CVD, resolve skin symptoms in patients with C4 CVD, and accelerate the healing of venous ulcers in patients with C6 CVD. MPFF is highly recommended in international guidelines of CVD management and is the only veno-active drug to receive guideline endorsement for an improvement in patient quality of life.

Efficacy and safety of micronized purified flavonoid fractions for the treatment of postoperative hemorrhoid complications: A systematic review and meta-analysis

BACKGROUND

Hemorrhoids, a common anorectal disease, seriously affects patients' quality of life. Micronized purified flavonoid fractions (MPFF) have been shown to improve hemorrhoid symptoms.

PURPOSE

To evaluate the efficacy and safety of MPFF in treating postoperative hemorrhoid complications.

STUDY DESIGN

A systematic review and meta-analysis of existing literature on natural compounds for treating postoperative complications of hemorrhoids.

METHODS

A literature search was conducted using five databases, namely PubMed, WanFang, CNKI, Embase, and the Cochrane Library, to identify randomized controlled trials (RCTs) on the effects of MPFF treatment on hemorrhoids. Stata 15.1 and Revman 15.4 were used to assess the data, while subgroup and sensitivity analyses were performed to evaluate potential heterogeneity, and trial sequential analysis (TSA) and Egger test were used to evaluate the reliability of each trial.

RESULTS

A total of 22 RCTs, including 2,335 participants were included in the analysis. MPFF improved the clinical efficacy of post-hemorrhoidectomy and reduced the bleeding rate, pain score, and edema score, although no substantial effect on adverse reactions was reported. Subgroup analyses showed a significant reduction in pain score and bleeding rate in trials with duration of 4-10 days and an improvement in clinical efficacy. Treatment for ≥ 10 days significantly improved the edema score; a dosage range of 1,800-2,700 mg/day of MPFF significantly reduced edema and pain scores, whereas < 1,800 mg/day significantly improved clinical efficacy.

CONCLUSIONS

Based on searching the relevant literatures, this is the first meta-analysis on MPFF treatment of postoperative hemorrhoid complications. Our findings, validated by TSA, suggest that MPFF is safe and effective in reducing postoperative hemorrhoid complications, and that dose and duration are key factors in its efficacy, as illustrated by subgroup analysis. However, due to the small sample size, the standardized treatment regimen of MPFF could not be obtained; therefore, further research is warranted.

Diosmin Alleviates Venous Injury and Muscle Damage in a Mouse Model of Iliac Vein Stenosis

Chronic venous disease (CVD) is a progressive inflammatory disease that increases in prevalence with age. Elucidating the underlying molecular mechanism of CVD development is essential for disease prevention and treatment. This study constructed a mouse model of iliac vein stenosis to explore the mechanism of the CVD disease progression, and diosmin was administered as a positive control (as recommended by clinical practice). The mouse model was established successfully with iliac vein stenosis, leading to the expansion of the intercellular space and venous leakage. Conversely, micronized diosmin showed a dose-dependent therapeutic effect for these manifestations. Concerning the mechanism, iliac vein stenosis caused an inflammatory response in veins, while diosmin suppressed this increase. Furthermore, RNA sequencing analysis indicated that diosmin significantly improved muscle function through actin filament organization and muscle contraction. These results indicated that the mouse model of iliac vein stenosis is a reliable model to study venous diseases. Furthermore, the dose-dependent therapeutic effect of diosmin on stenosis (without toxic side-effects) suggests greater protection against venous diseases at higher doses of diosmin.

Time course of microvalve pathophysiology in high pressure low flow model of venous insufficiency and the role of micronized purified flavonoid fraction

BACKGROUND

The aim of this study was to characterize, in an experimental model, the mechanisms involved in the initiation of venous insufficiency at the level of microvenous valve and whether they can be influenced by early treatment with micronized purified flavonoid fraction (MPFF).

METHODS

The external right iliac vein of 78 male golden Syrian hamsters was ligated to induce chronic venous insufficiency. Internal venular diameter as well as leukocyteendothelium-interaction (leukocytes sticking after staining with rhodamine 6G), were assessed using an intravital microscope. In the second part of the study 30 animals were divided into three groups and underwent: ligation plus MPFF, ligation plus 10% lactose solution (vehicle), or sham operation. Treatment with MPFF 100 mg/kg/day or vehicle started 2 days before ligation and lasted for 7 days. Venular diameter and number of adherent leukocytes were assessed 5 days post-ligature.

RESULTS

Venule diameter increased immediately after ligature and reached a maximum at 4 hours (P<0.001 vs baseline), followed by a plateau before gradually returning to baseline dimensions. The increase in the number of adherent leukocytes was also immediate but attained maximal number at 3 days (p<0.0001), followed by a plateau and then gradual return to baseline numbers. In MPFF-treated animals, leukocyte adhesion to the microvalves was prevented compared with vehicle-treated animals (p<0.0001) and venule diameter was also significantly reduced (p<0.05).

CONCLUSIONS

Venous hypertension induced immediate venule dilatation followed by an increase in the number of adherent leukocytes at microvalve level. Treatment with MPFF prevented the initiation of microvalve inflammation and may play a protective role in the progression of chronic venous insufficiency.

Micronized purified flavonoid fraction for the treatment of chronic venous insufficiency, with a focus on postthrombotic syndrome: A narrative review

INTRODUCTION

Postthrombotic syndrome (PTS) is a form of secondary chronic venous insufficiency (CVI) that occurs after deep vein thrombosis (DVT). Effective treatments for PTS are lacking. Micronized purified flavonoid fraction (MPFF) is a venoactive drug used in the treatment of CVI.

OBJECTIVE

To determine whether MPFF is a good candidate to explore as a therapeutic agent for PTS.

METHODS

We performed a narrative review in which we identified 14 systematic reviews, 33 randomized controlled trials, and 19 observational studies that discussed the use of MPFF in CVI, as well as studies that reported on the mechanistic action of MPFF in relation to the pathophysiology of PTS.

RESULTS

MPFF targets a number of pathophysiologic components of PTS. Based on animal models and human studies investigating objective vascular and lymphatic measures, MPFF promotes venous recanalization after DVT, decreases venous remodeling and reflux, inhibits inflammatory processes, improves venous tone and stasis, improves lymphatic circulation, improves capillary hyperpermeability, and decreases tissue hypoxia. Furthermore, MPFF shows promise in improving clinical manifestations, quality of life, and objective venous parameters of CVI. Studies suggest good patient acceptability and tolerability with the use of MPFF in CVI.

CONCLUSION

MPFF is a good candidate to explore as a potential therapy for PTS. Confirmatory high-quality studies are still needed to reinforce the evidence supporting the use of MPFF in CVI. Double-blind randomized controlled trials with clinical endpoints are needed to assess the clinical efficacy of MPFF in the treatment of PTS.

Micronized purified flavonoid fraction in the treatment of hemorrhoidal disease

Hemorrhoidal disease (HD) is common in adults. Treatment is largely conservative, although more invasive procedures may be required. Venoactive drugs such as micronized purified flavonoid fraction (MPFF) are widely used, but a recent and comprehensive review of supporting evidence is lacking. In acute HD, MPFF can reduce HD symptoms such as bleeding, pain, anal discomfort, anal discharge and pruritus. In patients undergoing surgery, postoperative adjunct MPFF consistently reduces pain, bleeding duration and use of analgesia. MPFF treatment is appropriate and effective both as a first-line conservative treatment and as a postoperative adjunct treatment. MPFF reduces the duration of hospital stay following surgery, facilitating a return to normal activity and improving quality of life. MPFF may also prevent HD recurrence.

Prospective comparative study evaluating the role of flavonoids after endovenous thermal ablation

OBJECTIVES

The aim of our study was to evaluate the role of flavonoids in the improvement of post-operative symptoms after endovenous thermal ablation (EVTA).

METHODS

A prospective comparative study of 120 consecutive patients undergoing EVTA of the greater saphenous vein associated with phlebectomies was undertaken. Patients were grouped in those receiving micronized purified flavonoid fraction (MPFF- 60 patients) agent 500 mg Bid 7 days pre- and 30 days post- operatively (MPFF group) and those in the control group (60 patients) who did not. Demographics, intra-operative details, Clinical -Etiology- Anatomy- Pathophysiology (CEAP) clinical class, 10-cm Visual Analog Scale (VAS) for pain, Venous Clinical Severity Score (VCSS) and Chronic Venous Insufficiency Quality-of-Life Questionnaire (CΙVIQ-20) were recorded. Primary outcome was the postoperative pain assessement using the VAS scale and CIVIQ pain score. Secondary outcomes included assessement of VCSS and CΙVIQ-20 scores.

RESULTS

There were no significant differences between the groups regarding demographics, clinical and procedural characteristics. Patients in MPFF group reported significantly lower VAS pain levels than control group at 7- (-3.6 ± 1.2 vs -2.7 ± 1.9, p < .0001) and 30- post-operative day (-4.9 ± 0.1 vs -4.2 ± 1, p < .0001). MPFF group also showed better outcome in terms of CIVIQ pain score at 7- (-3.7 ± 1.3 vs -3.5 ± 1.8, p = .008) and 30- post-operative day (-5.3. ± 1.1 vs -4.4 ± 1, p = .017). Both groups showed a significant improvement in VAS pain score (p = .047), global CIVIQ-20 (p = .009) and VCSS (p = .008) at 7- and 30-days post-operatively.

CONCLUSIONS

Administration of flavonoids in patients undergoing EVTA associated with phlebectomies reduces pain by a small amount during early postoperative period.

Effects of the Traditional Chinese Medical Prescription Linba Fang as a Treatment for Lymphedema

Lymphedema can lead to a series of complicated and irreversible chronic pathological changes, including lymphatic fluid retention, infiltration of inflammatory cells, lipid deposition, and fibrosis of the surrounding tissues. Typically, compression physiotherapy is recommended for early lymphedema. However, the chronic fluid compartments will lead to fat deposition, skin fibrosis, and hyperkeratosis. Few treatment methods are available for patients with lymphedema. Previous studies have attempted to apply diuretics, diosmin, and sodium β-aescinate to treatment for venous edema, but the curative effect was unsatisfactory. There is currently no established effective treatment for lymphedema. In this paper, we investigated the effects of the traditional Chinese medical prescription Linba Fang as a treatment for lymphedema using a mouse model. A lymphedema model was established in C57BL/6 mice through lymphatic ablation at the base of tails. Negative controls were administered with 0.5% sodium carboxymethyl cellulose solution by gavage twice daily, positive controls with aescuvenforte, and test mice with Linba Fang. Aescuvenforte and Linba Fang were dissolved in 0.5% sodium carboxymethyl cellulose solution to produce a homogeneous mixture. After treatment for 2-4 weeks, tail diameter and weight, inflammatory cytokine levels (IL-1, IL-6, and TNF-α), lipid deposition, and fibrosis were evaluated. The results showed that none of the mice died during the treatment with Linba Fang. The levels of tail swelling, inflammation, lipid deposition, and fibrosis in mice treated with Linba Fang were significantly decreased compared with negative and positive controls. Among mice treated with the same dose of Linba Fang, the levels of tail swelling, inflammation, lipid deposition, and fibrosis in mice treated for 4 weeks were significantly lower than those treated for 2 weeks. Among mice treated for the same duration of time, the levels of tail swelling, inflammation, lipid deposition, and fibrosis showed a decreasing tendency following increasing doses. Notably, the inflammation in tail tissues decreased to the similar level of normal group after treatment for 4 weeks using the high dose of Linba Fang. In conclusion, the traditional Chinese medical prescription Linba Fang could inhibit the pathological changes caused by lymphedema, including swelling, inflammation, lipid deposition, and fibrosis.

Metabolism and pharmacological activities of the natural health-benefiting compound diosmin

Diosmin is a famous natural flavonoid for treating chronic venous insufficiency and varicose veins.

Effect of valve lesion on venous valve cycle: A modified immersed finite element modeling

The present study aimed to understand the effect of venous valve lesion on the valve cycle. A modified immersed finite element method was used to model the blood–tissue interactions in the pathological vein. The contact process between leaflets or between leaflet and sinus was evaluated using an adhesive contact method. The venous valve modeling was validated by comparing the results of the healthy valve with those of experiments and other simulations. Four valve lesions induced by the abnormal elasticity variation were considered for the unhealthy valve: fibrosis, atrophy, incomplete fibrosis, and incomplete atrophy. The opening orifice area was inversely proportional to the structural stiffness of the valve, while the transvalvular flow velocity was proportional to the structural stiffness of the valve. The stiffening of the fibrotic leaflet led to a decrease in the orifice area and a stronger jet. The leaflet and blood wall shear stress (WSS) in fibrosis was the highest. The softening of the atrophic leaflet resulted in overly soft behavior. The venous incompetence and reflux were observed in atrophy. Also, the atrophic leaflet in incomplete atrophy exhibited weak resistance to the hemodynamic action, and the valve was reluctant to be closed owing to the large rotation of the healthy leaflet. Low blood WSS and maximum leaflet WSS existed in all the cases. A less biologically favorable condition was found especially in the fibrotic leaflet, involving a higher mechanical cost. This study provided an insight into the venous valve lesion, which might help understand the valve mechanism of the diseased vein. These findings will be more useful when the biology is also understood. Thus, more biological studies are needed.

Pathophysiological Mechanisms of Chronic Venous Disease and Implications for Venoactive Drug Therapy

Chronic venous disease (CVD) is a common pathology, with significant physical and psychological impacts for patients and high economic costs for national healthcare systems. Throughout the last decades, several risk factors for this condition have been identified, but only recently, have the roles of inflammation and endothelial dysfunction been properly assessed. Although still incompletely understood, current knowledge of the pathophysiological mechanisms of CVD reveals several potential targets and strategies for therapeutic intervention, some of which are addressable by currently available venoactive drugs. The roles of these drugs in the clinical improvement of venous tone and contractility, reduction of edema and inflammation, as well as in improved microcirculation and venous ulcer healing have been studied extensively, with favorable results reported in the literature. Here, we aim to review these pathophysiological mechanisms and their implications regarding currently available venoactive drug therapies.

Identify potential drugs for cardiovascular diseases caused by stress-induced genes in vascular smooth muscle cells

BACKGROUND

Abnormal proliferation of vascular smooth muscle cells (VSMC) is a major cause of cardiovascular diseases (CVDs). Many studies suggest that vascular injury triggers VSMC dedifferentiation, which results in VSMC changes from a contractile to a synthetic phenotype; however, the underlying molecular mechanisms are still unclear.

METHODS

In this study, we examined how VSMC responds under mechanical stress by using time-course microarray data. A three-phase study was proposed to investigate the stress-induced differentially expressed genes (DEGs) in VSMC. First, DEGs were identified by using the moderated t-statistics test. Second, more DEGs were inferred by using the Gaussian Graphical Model (GGM). Finally, the topological parameters-based method and cluster analysis approach were employed to predict the last batch of DEGs. To identify the potential drugs for vascular diseases involve VSMC proliferation, the drug-gene interaction database, Connectivity Map (cMap) was employed. Success of the predictions were determined using in-vitro data, i.e. MTT and clonogenic assay.

RESULTS

Based on the differential expression calculation, at least 23 DEGs were found, and the findings were qualified by previous studies on VSMC. The results of gene set enrichment analysis indicated that the most often found enriched biological processes are cell-cycle-related processes. Furthermore, more stress-induced genes, well supported by literature, were found by applying graph theory to the gene association network (GAN). Finally, we showed that by processing the cMap input queries with a cluster algorithm, we achieved a substantial increase in the number of potential drugs with experimental IC50 measurements. With this novel approach, we have not only successfully identified the DEGs, but also improved the DEGs prediction by performing the topological and cluster analysis. Moreover, the findings are remarkably validated and in line with the literature. Furthermore, the cMap and DrugBank resources were used to identify potential drugs and targeted genes for vascular diseases involve VSMC proliferation. Our findings are supported by in-vitro experimental IC50, binding activity data and clinical trials.

CONCLUSION

This study provides a systematic strategy to discover potential drugs and target genes, by which we hope to shed light on the treatments of VSMC proliferation associated diseases.

Vein graft adaptation and fistula maturation in the arterial environment

Veins are exposed to the arterial environment during two common surgical procedures, creation of vein grafts and arteriovenous fistulae (AVF). In both cases, veins adapt to the arterial environment that is characterized by different hemodynamic conditions and increased oxygen tension compared with the venous environment. Successful venous adaptation to the arterial environment is critical for long-term success of the vein graft or AVF and, in both cases, is generally characterized by venous dilation and wall thickening. However, AVF are exposed to a high flow, high shear stress, low-pressure arterial environment and adapt mainly via outward dilation with less intimal thickening. Vein grafts are exposed to a moderate flow, moderate shear stress, high-pressure arterial environment and adapt mainly via increased wall thickening with less outward dilation. We review the data that describe these differences, as well as the underlying molecular mechanisms that mediate these processes. Despite extensive research, there are few differences in the molecular pathways that regulate cell proliferation and migration or matrix synthesis, secretion, or degradation currently identified between vein graft adaptation and AVF maturation that account for the different types of venous adaptation to arterial environments.

Mechanical stretch increases MMP-2 production in vascular smooth muscle cells via activation of PDGFR-β/Akt signaling pathway

Increased blood pressure, leading to mechanical stress on vascular smooth muscle cells (VSMC), is a known risk factor for vascular remodeling via increased activity of matrix metalloproteinase (MMP) within the vascular wall. This study aimed to identify cell surface mechanoreceptors and intracellular signaling pathways that influence VSMC to produce MMP in response to mechanical stretch (MS). When VSMC was stimulated with MS (0–10% strain, 60 cycles/min), both production and gelatinolytic activity of MMP-2, but not MMP-9, were increased in a force-dependent manner. MS-enhanced MMP-2 expression and activity were inhibited by molecular inhibition of Akt using Akt siRNA as well as by PI3K/Akt inhibitors, LY293002 and AI, but not by MAPK inhibitors such as PD98059, SP600125 and SB203580. MS also increased Akt phosphorylation in VSMC, which was attenuated by AG1295, a PDGF receptor (PDGFR) inhibitor, but not by inhibitors for other receptor tyrosine kinase including EGF, IGF, and FGF receptors. Although MS activated PDGFR-α as well as PDGFR-β in VSMC, MS-induced Akt phosphorylation was inhibited by molecular deletion of PDGFR-β using siRNA, but not by inhibition of PDGFR-α. Collectively, our data indicate that MS induces MMP-2 production in VSMC via activation of Akt pathway, that is mediated by activation of PDGFR-β signaling pathways.

Diosmin – Isolation Techniques, Determination in Plant Material and Pharmaceutical Formulations, and Clinical Use

Diosmin is a naturally occurring flavone glycoside used in the treatment of venous diseases. In this review, we present the clinical aspects of the use of diosmin preparations in venous stasis, hemorrheologic disorders and vein wall remodeling. Because of its multiple applications in biology and its many therapeutic activities, research on isolation and identification of diosmin is of high relevance. The aim of this review is to present an overview of techniques of isolation and separation of diosmin in plant material, pharmaceutical formulations such as Daflon®, Diosed® and Dioven® tablets, and biological fluids.

The effects of doxycycline and micronized purified flavonoid fraction on human vein wall remodeling are not hypoxia-inducible factor pathway-dependent

BACKGROUND

Doxycycline and micronized purified flavonoid fraction (MPFF) modulate vein wall remodeling that may be associated with hypoxia in varicose veins (VVs), vein graft stenosis, and deep venous thrombosis. We recently reported that in vitro exposure of non-VV (NVVs) and VVs to hypoxic conditions activates the hypoxia-inducible factor (HIF) pathway. This study investigated the in vitro effects of doxycycline and MPFF on the HIF pathway in hypoxic NVVs and VVs.

METHODS

Six NVVs and six VVs obtained from surgery were used to prepare vein organ cultures, which were exposed to hypoxia (1% O(2)), with and without MPFF (10(-5) mol/L) or doxycycline (5 μg/mL) for 16 hours. The veins were analyzed for HIF-1α, HIF-2α, and their target gene expression, with real-time polymerase chain reaction and Western blot. The differences between gene expressions were tested with one-way analysis of variance with repeated measures, followed by the Dunnett test for multiple comparisons. P < .05 was considered significant.

RESULTS

Treatment of NVV organ cultures exposed to hypoxia with doxycycline or MPFF did not significantly alter the expression of HIF-1α and HIF-2α messenger (m)RNA and protein compared with untreated. Doxycycline also did not significantly affect the expression of HIF-1α and HIF-2α mRNA and protein in VVs exposed to hypoxia compared with untreated VVs. However, MPFF significantly reduced the expression of HIF-1α but not HIF-2α mRNA in VVs exposed to hypoxia compared with untreated VVs. Interestingly, the reduction of the expression of HIF-1α mRNA in VVs by MPFF was not reflected at the protein level. The mRNA expression of HIF target genes, namely glucose transporter-1, carbonic anhydrase-9, vascular endothelial growth factor, B-cell lymphoma 2/adenovirus E1B 19-kDa protein-interacting protein 3, prolyl hydroxylase domain-2, and prolyl hydroxylase domain-3, was not significantly altered in NVVs and VVs exposed to hypoxia and treated with doxycycline or MPFF compared with those untreated.

CONCLUSIONS

Doxycycline and MPFF at a concentration corresponding to a therapeutic dose do not alter the activation of the HIF pathway in NVV and VV organ cultures exposed to hypoxia. Our findings suggest vein wall remodeling actions in NVVs and VVs are likely not HIF-dependent.

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.

Acute venous occlusion enhances matrix metalloprotease activity: Implications on endothelial dysfunction

Venous hypertension is associated with microvascular inflammation, restructuring, and apoptosis, but the cellular and molecular mechanisms underlying these events remain uncertain. In the present study, we tested the hypothesis that elevated venous pressure and reduction of shear stress induce elevated enzymatic activity. This activity in turn may affect endothelial surface receptors and promote their dysfunction. Using a rodent model for venous hypertension using acute venular occlusion, microzymographic techniques for enzyme detection, and immunohistochemistry for receptor labeling, we found increased activity of the matrix metalloproteases (MMPs) -1, -8, and -9 and tissue inhibitors of metalloproteases (TIMPs) -1 and -2 in both high- and low-pressure regions. In this short time frame, we also observed that elevated venule pressure led to two different fates for the vascular endothelial growth factor receptor-2 (VEGFR2); in higher-pressure upstream regions, some animals exhibited higher VEGFR2 expression, while others displayed lower levels upstream compared to their downstream counterparts with lower pressure. VEGFR2 expression was, on average, more pronounced upon application of MMP inhibitor, suggesting possible cleavage of the receptor by activated enzymes in this model. We conclude that venous pressure elevation increases enzymatic activity which may contribute to inflammation and endothelial dysfunction associated with this disease by influencing critical surface receptors.

Pharmacological treatment in patients with C4, C5 and C6 venous disease

Background

A range of surgical, endovenous, physical and medical treatments are available for patients with chronic venous disease. The aim of this review was to evaluate the evidence for pharmacological agents used for the treatment of chronic venous disease.

Methods

A literature search was performed using Pubmed, Embase, Cochrane and Google Scholar databases. The initial search terms ‘varicose vein’, ‘venous ulcer’, ‘venous disease’ and ‘lipodermatosclerosis’ were used to identify relevant clinical studies of pharmacotherapy in patients with chronic venous disease (C4–C6).

Results

A huge range of naturally occurring and synthetic drugs have been studied in patients with chronic venous disease. For patients with C4 venous disease, micronized purified flavonoid fraction (MPFF), oxerutin, rutosides and calcium dobesilate may reduce venous symptoms and oedema. MPFF and pentoxifylline have been shown to improve venous ulcer healing when used in addition to multilayer compression bandaging. The clinical benefits of other medications remain unproven. Reliability of meta-analyses was limited by study heterogeneity, small sample sizes and lack of long-term follow-up.

Conclusions

In prospective randomized studies, MPFF (Daflon®), other flavonoid derivatives and pentoxifylline have demonstrated clinical benefits in patients with C4–C6 venous disease. Pharmacotherapy should be part of a range of treatment options in the modern management of patients with chronic venous disorders.