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Heart failure (HF) has high event rates, mortality, and is challenging to manage in clinical practice. Clinical management is complicated by complex therapeutic strategies in a population with a high prevalence of comorbidity and general frailty. In the last four years, an abundance of research has become available to support multidisciplinary management of heart failure from within the hospital through to discharge and primary care as well as supporting diagnosis and comorbidity management. Within the hospital setting, recent evidence supports sacubitril-valsartan combination in frail, deteriorating or de novo patients with LVEF≤40%. Furthermore, new strategies such as SGLT2 inhibitors and vericiguat provide further benefit for patients with decompensating HF. Studies with tafamidis report major clinical benefits specifically for patients with ATTR cardiac amyloidosis, a remaining underdiagnosed and undertreated disease. New evidence for medical interventions supports his bundle pacing to reduce QRS width and improve haemodynamics as well as ICD defibrillation for non-ischemic cardiomyopathy. The Mitraclip reduces hospitalisations and mortality in patients with symptomatic, secondary mitral regurgitation and ablation reduces mortality and hospitalisations in patients with paroxysmal and persistent atrial fibrillation. In end-stage HF, the 2018 French Heart Allocation policy should improve access to heart transplants for stable, ambulatory patients and, mechanical circulatory support should be considered to avoid deteriorating on the waiting list. In the community, new evidence supports that improving discharge education, treatment and patient support improves outcomes. The authors believe that this review fills the gap between the guidelines and clinical practice and provides practical recommendations to improve HF management., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

Background: Microvascular obstruction (MVO) is associated with poor outcome after ST-segment elevation myocardial infarction (STEMI). Vascular endothelial growth factor-A (VEGF-A) is a vascular permeability inducer playing a key role in MVO pathogenesis. We aimed to assess whether VEGF-A levels are associated with MVO, when evaluated by magnetic resonance imaging (MRI) in STEMI patients., Methods: The multicenter prospective PREGICA study included a CMR substudy with all consecutive patients with a first STEMI who had undergone cardiac MRI at baseline and at 6-month follow-up. Patients with initial TIMI flow >1 were excluded. VEGF-A levels were measured in blood samples drawn at inclusion., Results: Between 2010 and 2017, 147 patients (mean age 57 ± 10 years; 84% males) were included. MVO was present in 65 (44%) patients. After multivariate analysis, higher troponin peak (OR 1.005; 95% CI 1.001-1.008; p = 0.007) and VEGF-A levels (OR 1.003; 95% CI 1.001-1.005; p = 0.015) were independently associated with MVO. When considering only patients with successful percutaneous coronary intervention (final TIMI flow 3, n = 130), higher troponin peak (p = 0.004) and VEGF-A levels (p = 0.03) remained independently predictive of MVO. Moreover, MVO was associated with adverse left ventricular (LV) remodeling and VEGF-A levels were significantly and inversely correlated with LV ejection fraction (EF) at 6-month follow-up., Conclusion: Our results show that VEGF-A levels were independently associated with MVO during STEMI and correlated with mid-term LVEF alteration. VEGF-A could therefore be considered as a biomarker of MVO in STEMI patients and be used to stratify patient prognosis., (Copyright © 2019. Published by Elsevier B.V.)

Background: Coronary lesions characteristics as well as patient thrombogenicity can explain coronary events manifestation. In young patient, local conditions are usually less important and thrombogenicity could play a significant role. Assessing thrombophilia could be justified in young patients and may induce an adapted therapeutic management., Purpose: We aimed to assess the prevalence of thrombophilia and therapeutic modification in young adults aged≤55 years admitted in our department for ST elevation myocardial infarction (STEMI)., Methods: From January 2013 to January 2017, data on all patients aged≤55 years with STEMI admitted in emergency were retrospectively retrieved from our database. Thrombophilia investigation was made regarding clinical (with or without cardiovascular risk factors [CVRF]), biological and/or angiographic evaluation., Results: A total of 133 patients aged≤55 years with STEMI were included. Cardiac arrest occurred in 15 patients (11%). One or less CVRF were found in 47 patients (35%). Smoking was reported in 93 patients (70%) and drug addiction (cannabis, cocaine) in 19 patients (14%). A subset of 51 patients (38%) were screened for thrombophilia. Patients with thrombophilia assessment were younger, less active smokers and presented less CVRF than patients without investigation (P<0.001). Single vessel diseased was found in 88 patients (66%). No differences regarding coronary procedural characteristic were found between the two groups. The most frequently encountered aetiology, found in 122 patients (92%), was de novo intra-arterial thrombosis related to atherosclerosis. In patients with thrombophilia assessment (n=51), one or more abnormal biological results was found in 22 patients (43%) and a therapeutic adjustment was made in 6 patients (12%)., Conclusion: Thrombophilia screening in young STEMI adults showed an abnormality in 43% of cases. Antithrombotic treatment can be modified after its demonstration., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Background: Direct stenting is the best method for achieving reperfusion in primary percutaneous coronary intervention (PPCI). We hypothesized that the use of a microcatheter (MC) during PPCI when Thrombolysis in Myocardial Infarction (TIMI) flow ≤ 1 after wire crossing would allow visualization of the downstream artery with an optimal TIMI 3 flow at the end of the procedure., Methods: In this pilot study, PPCI patients with TIMI flow ≤ 1 after wire crossing formed the MC group (n = 60); the MC was positioned in the distal part of the culprit artery and a small amount of contrast was injected through it to determine stent size and length to treat the culprit lesion. The MC group was compared with previous consecutive patients treated using standard PPCI (n = 94; similar characteristics except for the rate of previous percutaneous coronary intervention)., Results: In the MC group, downstream arteries were visualized in 98% of cases and direct stenting was achieved in 72% vs 31% (P < 0.0001). Final TIMI 3 flow was similar in both groups (97%). There was less manual thrombectomy (20% vs 63%; P < 0.001) and bailout glycoprotein IIb/IIIa inhibitor use (6.7% vs 29.8%; P < 0.002). The incidence of major adverse events (death, shock, severe arrhythmia) and left ventricular ejection fraction were similar. The peak cardiac enzymes level was significantly lower in the MC group., Conclusions: The MC strategy appears feasible and safe. It could allow exploring new strategies on the basis of more systematic direct stenting and prepared reperfusion by injecting drugs through the MC before reperfusion., (Copyright © 2017 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.)

Heart failure can be associated with inflammation but it is unclear if inflammation is directly related to hemodynamic worsening or is an independent pathway. Our aim was to investigate inflammation and mechanical stress using serial measurements of biomarkers in acute and chronic heart failure with reduced ejection fraction (AHF and CHF)., Method: The following biomarkers were measured on admission, at discharge and one month after discharge: B-type natriuretic peptide (BNP), high-sensitivity C-Reactive protein (hsCRP), Tumour Necrosis Factor alpha (TNFα), interleukin 6 (IL6), myeloperoxidase (MPO), suppression of tumorigenicity 2 (ST2), mid-regional pro-adrenomedullin (MR-proADM), galectin 3 (Gal3), Growth differentiating factor 15 (GDF15) and procalcitonin (PCT)., Results: In control CHF group (n=20, 69±11y, NYHA 1-2), most biomarker levels were low and stable over time. In AHF (n=55, 71±14y), BNP, ST2 and GDF15 levels were highly increased on admission and then decreased rapidly with clinical improvement; BNP, ST2 and GDF15 levels were statistically correlated (r=0.64, 0.46 and 0.39; p<0.001 for both). Both hsCRP, MPO, TNFα and Gal3 levels were increased in most AHF patients (70, 56, 83 and 98% respectively) with poor change over time. HsCRP, MPO and TNFα levels were correlated. IL6, MR-proADM and PCT levels were slightly increased, without change over time. Highest quartiles of BNP and ST2 were associated with death or readmission at one year (HR 2.33 [95CI 1.13-4.80] and 2.42 [1.27-4.60])., Conclusion: AHF is associated with systemic inflammation. This inflammatory response continued up to one month after discharge despite normalisation of mechanical stress-related markers., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Background: Fractional flow reserve (FFR) measurement requires adenosine injection. However, adenosine can induce conductive and rhythmic complications, or be contraindicated in some patients. Contrast-induced hyperemia could provide a simple first-line method (contrast-enhanced FFR; cFFR) to assess coronary lesions. In this study we evaluated the accuracy of cFFR to predict lesion significance., Methods: This prospective study included 104 patients with 138 coronary lesions. Each stenosis was evaluated using resting distal coronary pressure to aortic pressure ratio (Pd/Pa) measurements using intracoronary iodixanol (cFFR) and adenosine (FFR) injection. An FFR value ≤ 0.8 defined a significant lesion., Results: Dose-ranging analysis (n = 12 lesions) showed that 10 mL iodixanol was required to obtain the lowest cFFR value. Intermeasurement reproducibility of cFFR (n = 18 lesions) showed limited variability and small mean estimated bias (0.001 ± 0.014). Values of cFFR and FFR were highly correlated in a first series of n = 36 lesions (r = 0.9; P < 0.001). Receiver-operating characteristic curve analysis showed an excellent accuracy of cFFR cutoff value of ≤ 0.85 in predicting FFR value ≤ 0.80 (area under the curve, 0.94; 95% confidence interval, 0.90-0.98; sensitivity, 95%; specificity, 73%). This threshold was then tested prospectively in an independent cohort of n = 72 lesions. A cFFR value ≤ 0.85 correctly identified hemodynamically significant lesions with a sensitivity of 100%, specificity of 78%, positive predictive value of 78%, and negative predictive value of 100%., Conclusions: cFFR is reproducible and can be achieved with usual volumes of contrast. A cFFR threshold value of 0.85 provides excellent sensitivity and negative predictive value in coronary artery stenosis., (Copyright © 2016 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.)

Objectives: This study sought to hypothesize that elevated B-type natriuretic peptide (BNP) could act as an endogenous neprilysin inhibitor., Background: A hallmark of acute decompensated heart failure (ADHF) is the overproduction of natriuretic peptides (NPs) by stretched cardiomyocytes. Various strategies have been developed to potentiate the beneficial effect of the NPs, including the recent use of neprilysin angiotensin receptor inhibitors. Contrary to rodents, human BNP is poorly sensitive to neprilysin degradation while retaining affinity to neprilysin., Methods: We enrolled 638 patients presenting to the emergency department with acute dyspnea of which 468 had ADHF and 169 had dyspnea of noncardiac origin. We also included 46 patients with stable chronic heart failure (HF) and 10 age-matched healthy subjects. Plasma samples were collected within 4 h after emergency department admission. BNP, neprilysin concentration and activity, and the neprilysin substrate substance P concentration were measured., Results: We found that when plasma BNP rose above 916 pg/ml, neprilysin activity was markedly reduced (p < 0.0001) and stratified 95% of the population into 2 groups: BNP <916 pg/ml/neprilysin activity ≥ 0.21 nmol/ml/min and BNP ≥916 pg/ml/neprilysin activity <0.21 nmol/ml/min with very different prognoses. In vitro, BNP was responsible for neprilysin inhibition. Neprilysin activity was inversely correlated with the concentration of substance P (ρ = -0.80; p < 0.0001)., Conclusions: Besides being an effector of the cardiac response to cardiomyocyte stretching in ADHF, elevated plasma BNP is also an endogenous neprilysin inhibitor. A biologically relevant BNP threshold discriminates 2 populations of HF patients with different vasoactive peptide profiles and outcome. If confirmed, this may identify an important threshold for managing HF patients., (Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: We compared diagnostic and prognostic properties of brain natruiretic peptide (BNP), proBNP, NT-proBNP and MR-pro-atrial natriuretic peptide (ANP) in patients admitted with shortness of breath (SOB)., Methods: All 4 NPs were measured in patients admitted to the emergency unit with SOB (in 2 centers) or acute heart failure (AHF) (1 FINN-AKVA cohort) and in a control population of stable chronic HF. Follow-up was 1 (2 centers) and 5 years (1 FINN-AKVA cohort). Area under the curve (AUC) was used to assess diagnostic properties. AUC, multivariate Cox regression, net reclassification improvement (NRI), and Kaplan-Meier analyses were used to assess mortality., Results: We included 710 patients ("Biomarcoeurs" cohort n=336; FINN-AKVA study, n=306; stable chronic HF, n=68). Pro-BNP was almost as powerful as BNP to diagnose AHF (AUC 0.953 vs 0.973 respectively, p=0.003), NT-proBNP also performed well (0.922, p<0.001 vs BNP). MR-proANP performed less well (0.901). AUC over time showed greater MR-proANP values over the first year. At 5 years, MR-proANP had the best prognostic value (AUC 0.668 vs 0.604 for BNP, p=0.042). Kaplan Meier analysis confirmed better survival with MR-proANP≤416.8 pmol/L at 5 years. NRI at 5 years was greater for MR-proANP (0.23, p<0.05) than for proBNP, BNP or NTproBNP (p=NS)., Conclusion: Our study provides firm evidence that all NPs perform equally well for diagnostic purposes, and that MR-proANP has long term prognostic value in patients with acute heart failure., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Aim: This study aims to evaluate the incremental value of plasma biomarkers to traditional clinical variables for risk stratification of 30-day and one-year mortality in acutely decompensated heart failure (ADHF)., Methods and Results: Through an international collaborative network, individual patient data on 5306 patients hospitalized for ADHF were collected. The all-cause mortality rate was 11.7% at 30 days and 32.9% at one year. The clinical prediction model (age, gender, blood pressure on admission, estimated glomerular filtration rate <60 mL/min/1.73 m(2), sodium and hemoglobin levels, and heart rate) had a c-statistic of 0.74 for 30-day mortality and 0.73 for one-year mortality. Several biomarkers measured at presentation improved risk stratification when added to the clinical model. At 30 days, the net reclassification improvement (NRI) was 28.7% for mid-regional adrenomedullin (MR-proADM; p<0.001) and 25.5% for soluble (s)ST2 (p<0.001). At one year, sST2 (NRI 10.3%), MR-proADM (NRI 9.1%), amino-terminal pro-B-type natriuretic peptide (NT-proBNP; NRI 9.1%), mid-regional proatrial natriuretic peptide (MR-proANP; NRI 7.4%), B-type natriuretic peptide (NRI 5.5%) and C-reactive protein (CRP; NRI 5.3%) reclassified patients with ADHF (p<0.05 for all). CRP also markedly improved risk stratification of patients with ADHF as a dual biomarker combination with MR-proADM (NRI 36.8% [p<0.001] for death at 30 days) or with sST2 (NRI 20.3%; [p<0.001] for one-year mortality)., Conclusion: In this study, biomarkers provided incremental value for risk stratification of ADHF patients. Biomarkers such as sST2, MR-proADM, natriuretic peptides and CRP, reflecting different pathophysiologic pathways, add prognostic value to clinical risk factors for predicting both short-term and one-year mortality in ADHF., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

When the syndrome of heart failure (HF) is due to left ventricular (LV) systolic dysfunction the clinical manifestations and natural history of the syndrome depend primarily on the severity of LV systolic dysfunction. In contrast, when the syndrome is attributed to LV diastolic dysfunction multiple comorbidities are responsible for the clinical manifestations and the natural history of the syndrome. The present review underscores the multifactorial pathogenesis of the syndrome of HF associated with LV diastolic dysfunction that nowadays is more properly referred to as HF with preserved LV ejection fraction (HFpEF) than to diastolic HF. The prognosis is similarly poor whether HF is due to systolic dysfunction or associated with diastolic dysfunction. The cause of death that is commonly non-cardiovascular in HFpEF supports the pathogenic importance of comorbidities in this condition. Hypertension, chronic kidney disease (CKD), diabetes, obesity and sleep disorder breathing are among the most frequent comorbidities in HFpEF. These comorbidities account for the multiple clinical presentations of the syndrome of HFpEF. Limited functional capacity is in HFpEF largely related to the downward spiral between CKD mediated fluid accumulation and LV stiffness as well as altered ventricular-vascular coupling. The diagnosis of HFpEF currently relies on 2D-Doppler echocardiography findings of impaired LV relaxation and increased LV stiffness and to a lesser extent on biomarkers. Owing to both lack of stringent inclusion and exclusion enrollment criteria and mistaken therapeutic target, placebo-controlled randomized therapeutic trials have been so far negative in HFpEF., (Copyright © 2012 Société nationale française de médecine interne (SNFMI). Published by Elsevier SAS. All rights reserved.)

Beta-blockers play a pivotal role in the treatment of chronic systolic heart failure. However, the pharmacological family of beta-blockers is inhomogeneous regarding their pharmacological properties and their clinical effects can differ substantially according to different pharmacological properties. Because of vasodilator effects, the third generation of beta-blockers has additional potential across the cardiovascular diseases, from hypertension to heart failure. Nebivololol has both high selectivity for beta1-adrenergic receptors, no intrinsic sympathetic activity and ability to stimulate endothelial nitric oxide production. Such properties result in specific hemodynamic effects compared with others beta-blockers. Such properties also result in both high tolerability and positive metabolic effects which are crucial in high-risk groups. In the SENIORS trial, nebivolol demonstrated its efficacy and high tolerability in elderly patients with chronic heart failure irrespective of the left ventricular ejection fraction. More clinical trials would be useful to exhibit specific benefits of nebivolol in other high-risk groups of patients., (Copyright 2010. Published by Elsevier SAS.)

Objective: We studied prevalence, causes and consequences of worsening renal function (WRF) during hospitalization for acute heart failure (AHF)., Methods: Patients admitted for AHF were enrolled. Patients with severe chronic renal failure, cardiogenic shock and contrast medium-induced nephropathy were excluded. WRF was defined as an increase of 25 mumol/l or more in serum creatinine relative to the admission level. Survivors were monitored for 6 months, focusing on deaths and first unscheduled readmissions for heart failure., Results: Among the included 416 patients, WRF occurred in 152 cases (37%), 5+/-3 days after admission, and two-thirds of patients recovered their baseline renal function before discharge. Old age, diabetes, hypertension and acute coronary syndromes increased the risk of WRF. In-hospital furosemide doses as well as discharge treatment were similar in WRF and no-WRF patients. Serum creatinine elevation was the strongest independent determinant of a longer hospital stay (r=0.37, p=0.001). Adverse events occurred in 158 patients (38%) during follow-up, with 23 deaths and 135 readmissions. Cox analysis showed that WRF, transient or not, was an independent predictor of the risk of death or readmission (hazard ratio=1.74 [1.14-2.68], p=0.01)., Conclusion: WRF is frequent after admission for AHF and, although transient, is associated with longer hospitalization and with a higher risk of death and readmission, irrespectively of baseline renal function.

We report the case of a man admitted for massive pulmonary embolism. Transthoracic echocardiography showed a serpentine thrombus in the right atrium across the foramen oval. Because of an acute worsening of the circulatory insufficiency, an intravenous thrombolysis was prescribed and the patient recovered progressively. An early control echocardiography showed the disappearing of the intracardiac thrombus and no evidence of abnormality of interatrial septum. While there was no evidence of venous thrombosis in legs, a renal cancer was diagnosed by echography. Silent stroke were highlighted at the scanner. This clinical case leads to discuss the origin of thrombus (in situ formation or thrombus migration) as well as the treatment (heparinotherapy, thrombolysis, surgical embolectomy, definitive closure of the foramen oval).

Study Objectives: To assess the pulmonary hemodynamic characteristics in COPD candidates for lung volume reduction surgery (LVRS) or lung transplantation (LT)., Design: Retrospective study., Setting: One center in France., Patients: Two hundred fifteen patients with severe COPD who underwent right-heart catheterization before LVRS or LT., Results: Mean age was 54.6 years. Pulmonary function test results were as follows: FEV(1), 24.3% predicted; total lung capacity, 128.3% predicted; residual volume, 259.7% predicted. Mean pulmonary artery pressure (PAPm) was 26.9 mm Hg. Pulmonary hypertension (PAPm > 25 mm Hg) was present in 50.2% and was moderate (PAPm, 35 to 45 mm Hg) or severe (PAPm > 45 mm Hg) in 9.8% and in 3.7% of patients, respectively. Cardiac index was low normal. PAPm was related to Pao(2) and alveolar-arterial oxygen gradient in multivariate analysis. Cluster analysis identified a subgroup of atypical patients (n = 16, 7.4%) characterized by moderate impairment of the pulmonary mechanics (mean FEV(1), 48.5%) contrasting with high level of pulmonary artery pressure (PAPm, 39.8 mm Hg), and severe hypoxemia (mean Pao(2), 46.2 mm Hg)., Conclusion: While pulmonary hypertension is observed in half of the COPD patients with advanced disease, moderate-to-severe pulmonary hypertension is not a rare event in these patients. We individualized a subgroup of patients presenting with a predominant vascular disease that could potentially benefit from vasodilators.

Medical treatment of acute decompensated heart failure has little changed in the last years, except with the advent of non-invasive ventilation. Doppler-echocardiography and BNP dosing have simplified the diagnostic approach and limited the need for invasion evaluation. Vasodilators remain probably underused whereas some doubts have emergency regarding the safety of positive inotropes. Analysis of the hemodynamic profile is mandatory for an optimal management of these patients. The next decade will be that of morbimortality trials in this common form of heart failure with severe prognosis.

Introduction: Papillary fibroelastoma is a benign cardiac tumor which can be associated with serious embolic complications., Exegesis: We report on a 42-year-old man admitted for an ischemic stroke in the left middle cerebral artery region. Transesophageal echocardiography revealed a mitral valve tumor. Surgical excision and histological examination showed a papillary fibroelastoma. Clinical course was uneventful., Conclusion: We consider the high embolic potential of this tumor, which represents a surgically treatable cause of ischemic stroke.

Pharmacological and validated treatment of chronic heart failure (HF) includes successively angiotensin converting enzyme inhibitors (ACEi), beta-blockers and antialdosterone, which is associated with diuretics. The effectiveness of this manner in which to block more and more hormonal systems demonstrate the validity of the "hormonal" paradigm to explain heart failure. Therefore broader educational means are required to increase the prescription of these drugs for HF. Several questions about these drugs remain unresolved: HF with preserved systolic function and elderly patients, class effect, and the role of antagonists of angiotensin II receptors (as an alternative or associated with ACEi). Other short- and mid-term pharmacological perspectives target target hormonal systems and cytokines: endothelin-receptor antagonists, inhibition of natriuretic peptide degradation (via neutral endopeptidase), and newer drugs acting against TNF such as etanercept. Moreover, recent knowledge about molecular mechanisms of myocardium remodeling allows new drug strategies with target more specifically remodeling such as metalloproteinases. Finally, these perspectives should be largely modified by on-going research in the field of genomics.

Isolated acute right ventricular (RV) infarction is rare, and ECG diagnosis may be difficult. We report two cases of acute myocardial infarction with ST-segment elevation in anterior precordial leads caused by such an RV involvement. Potential mechanisms for the relationship are given.

Studies conducted over recent years have definitively confirmed beta-blockers as the major treatment for heart failure. However, they are difficult to use and, to date, only carvedilol has been granted a Marketing Authorisation for this indication. The practical aspects of treatment with carvedilol in these patients are reviewed.

Brain natriuretic peptide (BNP) is a recently discovered peptide, secreted by the atria and ventricles in response to parietal distension. It was recently proposed as a screening test for left ventricular failure. The authors assayed this peptide at rest in 37 patients with chronic heart failure due to left ventricular systolic dysfunction and another 20 patients with various diseases (respiratory failure, cirrhosis, heart transplantation, "diastolic" heart failure) but normal left ventricular systolic function. A significant increase compared to normal values was observed not only in the group of heart failure patients, but also in patients with all other diseases. BNP was significantly higher in NYHA class IV patients. The relationship between plasma BNP levels and ejection fraction was not significant. On the other hand, a good correlation was observed between BNP and left ventricular filling parameters evaluated by cardiac Doppler: E wave deceleration time (r = -0.53, p = 0.001), E/A ratio: r = 0.57 p = 0.005) or VO2 max (r = -0.55, p < 0.005).

Fucan, a sulfated polysaccharide extracted from brown seaweeds, inhibits smooth muscle cell (SMC) proliferation with a higher antiproliferative activity than heparin (Logeart et al., Eur. J. Cell Biol. 74, 1997, this issue). In order to investigate the structure-activity relationship of fucan on SMC growth, we have prepared by size exclusion chromatography fucan fractions of various molecular masses ranging from 5.5 to 556 kDa. Our experiments showed that the antiproliferative activity is dependent on the molecular weight of the polysaccharide. The molecular weight threshold indicated that about 30 saccharidic units on fucan were necessary to give the antiproliferative activity on SMCs. A kinetics study of DNA synthesis using tritiated thymidine uptake was also performed with different molecular weight fucan fractions. Although all tested fractions acted as soon as the cells enter the first cell cycle, the duration and potency of action varied. Moreover, displacement experiments of iodinated fucan revealed that the low molecular fucan fraction interacted weakly with the binding sites. Finally, gel permeation chromatography of internalized radiolabeled heparin and fucans was performed with SMCs. A rapid degradation of internalized heparin was observed, whereas only low molecular weight fucan fractions were partially degraded by SMCs. Together, these results indicate the significance of molecular weight on the antiproliferative activity of fucans on SMCs, and might help to understand their mechanism of action. In addition, the degradation experiments with internalized heparin and fucans ruled out a direct link between polysaccharide degradation and the antiproliferative effect on SMCs.

Smooth muscle cell (SMC) proliferation is inhibited both in vivo and in vitro by heparin. However, the precise mechanisms of action are still not understood. The analogy between two sulfated polysaccharides, heparin and fucan, has led us to compare in detail their effects on SMC growth. We have prepared and characterized a 19 kDa fucan fraction from brown seaweed, Ascophyllum nodosum. Fucan affects the growth of SMCs in a time- and dose-dependent, reversible and non-toxic fashion. As determined by cell counting, [3H]thymidine incorporation, and microcytofluorimetry analysis, heparin was less active than fucan in inhibiting SMC growth. Fucan and heparin act by preferential blocking of G0/G1, thus decreasing the G0/S transition. Binding experiments with [125I]fucan indicated saturable, unlabeled-fucan displaceable binding sites with an apparent Kd of 30 nM. Moreover, displacement experiments performed with various polysaccharides revealed that antiproliferative compounds interacted with these membrane sites, but non-antiproliferative polysaccharides (dextran, chondroitin sulfate) did not, providing evidence of a correlation between binding to SMCs and their antiproliferative activity. When cells were exposed at 37 degrees C to a fluorescent 5-([4,6-dichlorotriazin-2-yl]-amino)fluorescein (DTAF)-fucan, internalization occurred and punctate vesicles were observed which accumulated rapidly in the perinuclear region as previously reported for heparin. Nuclear preparations (membranes + contents) of cultured SMCs previously incubated with radiolabeled heparin or fucan indicated the presence of radioactivity, suggesting an antiproliferative action of both polysaccharides at the nuclear level. Collectively, these observations indicated that fucan and heparin share some similar mechanisms of action, such as SMC growth inhibition, binding, and internalization. In the accompanying paper (Logeart et al., Eur. J. Cell Biol. 74, 1997, this issue), we describe the effect of fucans of different molecular weights and conclude that there is no direct link between polysaccharide degradation and the antiproliferative effect on SMCs.