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Hans Vink - One of the best experts on this subject based on the ideXlab platform.
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Assessment and Imaging of the Cerebrovascular Glycocalyx
Current Neurovascular Research, 2016Co-Authors: Roel H.l. Haeren, Hans Vink, Steffi E. Van De Ven, Marcus Anna Maria Jacobus Van Zandvoort, Jacobus J. Van Overbeeke, Govert Hoogland, Kim RijkersAbstract:The Glycocalyx is a gel-like layer lining the luminal surface of the endothelium. The Glycocalyx exerts an important barrier role because it prevents exposure of plasma components to the endothelial surface. Disruption of the Glycocalyx by local inflammation or ischemia results in decreased Glycocalyx thickness which is associated with a number of vascular diseases. The cerebrovascular Glycocalyx has sparsely been studied, but is of great interest because of its potential role in cerebrovascular disease. In this review, we describe all existing techniques to visualize the Glycocalyx and designate techniques that may be suitable for studying the cerebrovascular Glycocalyx. A total of seven imaging techniques are discussed thoroughly, including transmission electron microscopy, intravital microscopy, micro-particle image velocimetry, confocal laser scanning microscopy, two-photon laser scanning microscopy, orthogonal polarization spectral imaging and sidestream dark field/oblique imaging. Measurement of serum concentrations of Glycocalyx-specific constituents is another method for Glycocalyx analysis. Also, we have reviewed the methods of Glycocalyx analysis by using these imaging techniques. So far, the cerebrovascular Glycocalyx has only been studied in vitro. However, other cerebral microcirculatory properties have been studied in vivo. This suggests that the cerebrovascular Glycocalyx can be studied in vivo by using some of the described techniques, when specific software is subjoined to the analysis. In conclusion, we have summarized techniques available for Glycocalyx assessment, and explained the significance and technical possibilities regarding cerebrovascular Glycocalyx visualization. Cerebrovascular Glycocalyx assessment would add valuable information to our understanding of the pathophysiology of cerebrovascular disease. Moreover, as a part of the blood-brain barrier, more knowledge on the cerebrovascular Glycocalyx may lead to better understanding of neurodegenerative conditions that are caused by a compromised blood-brain barrier including Alzheimer's disease, vascular dementia, multiple sclerosis and epilepsy.
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Damage of the Endothelial Glycocalyx in Dialysis Patients
Journal of The American Society of Nephrology, 2012Co-Authors: Carmen A. Vlahu, Bregtje A Lemkes, Dirk G. Struijk, M. G. Koopman, Raymond T. Krediet, Hans VinkAbstract:Damage to the endothelial Glycocalyx, which helps maintain vascular homeostasis, heightens the sensitivity of the vasculature to atherogenic stimuli. Patients with renal failure have endothelial dysfunction and increased risk for cardiovascular morbidity and mortality, but the state of the endothelial Glycocalyx in these patients is unknown. Here, we used Sidestream Darkfield imaging to detect changes in Glycocalyx dimension in dialysis patients and healthy controls from in vivo recordings of the sublingual microcirculation. Dialysis patients had increased perfused boundary region and perfused diameters, consistent with deeper penetration of erythrocytes into Glycocalyx, indicating a loss of Glycocalyx barrier properties. These patients also had higher serum levels of the Glycocalyx constituents hyaluronan and syndecan-1 and increased hyaluronidase activity, suggesting the shedding of these components. Loss of residual renal function had no influence on the imaging parameters but did associate with greater shedding of hyaluronan in blood. Furthermore, patients with higher levels of inflammation had more significant damage to the Glycocalyx barrier. In conclusion, these data suggest that dialysis patients have an impaired Glycocalyx barrier and shed its constituents into blood, likely contributing to the sustained endothelial cell activation observed in ESRD.
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degradation of the endothelial Glycocalyx is associated with chylomicron leakage in mouse cremaster muscle microcirculation
Thrombosis and Haemostasis, 2010Co-Authors: Alina A. Constantinescu, Hans Vink, Jos A. E. Spaan, E K Arkenbout, Jurgen W G E VanteeffelenAbstract:A thick endothelial Glycocalyx contributes to the barrier function of vascular endothelium in macro- and microcirculation. We hypothesised in the current study that diet-induced hyperlipidaemia perturbs the Glycocalyx, resulting in decreased dimensions of this layer and increased transendothelial lipoprotein leakage in capillaries. Glycocalyx thickness was measured in mouse cremaster muscle capillaries by intravital microscopy from the distance between flowing red blood cells and the endothelial surface. In control C57BL/6 mice on standard chow, Glycocalyx thickness measured 0.58 ± 0.01 (mean ± SEM) μm, and no lipoproteins were observed in the tissue. After three months administration of an either mild or severe high-fat / high-cholesterol diet (HFC) to C57BL/6 and ApoE3-Leiden mice, circulating large lipoproteins appeared into the subendothelial space in an increasing proportion of cremaster capillaries, and these capillaries displayed reduced Glycocalyx dimensions of 0.40 ± 0.02 and 0.30 ± 0.01 μm (C57BL/6 mice), and 0.37 ± 0.01 and 0.28 ± 0.01 μm (ApoE3-Leiden mice), after the mild and severe HFC diet, respectively. The chylomicron nature of the accumulated lipoproteins was confirmed by observations of subendothelial deposition of DiI-labeled chylomicrons in capillaries after inducing acute Glycocalyx degradation by heparitinase in normolipidaemic C57BL/6 mice. It is concluded that while under control conditions the endothelial Glycocalyx contributes to the vascular barrier against transvascular lipoprotein leakage in the microcirculation, diet-induced hyperlipidaemia reduces the thickness of the Glycocalyx, thereby facilitating leakage of chylomicrons across the capillary wall.
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effect of sulodexide on endothelial Glycocalyx and vascular permeability in patients with type 2 diabetes mellitus
Diabetologia, 2010Co-Authors: Lysette N Broekhuizen, Erik S.g. Stroes, Max Nieuwdorp, Bregtje A Lemkes, Hans L Mooij, Marijn C Meuwese, H J Verberne, F Holleman, Reinier O Schlingemann, Hans VinkAbstract:Aims/hypothesis Endothelial Glycocalyx perturbation contributes to increased vascular permeability. In the present study we set out to evaluate whether: (1) Glycocalyx is perturbed in individuals with type 2 diabetes mellitus, and (2) oral Glycocalyx precursor treatment improves Glycocalyx properties.
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Endothelial Glycocalyx dimensions are reduced in growing collateral arteries and modulate leucocyte adhesion in arteriogenesis
Journal of Cellular and Molecular Medicine, 2009Co-Authors: Sebastian Grundmann, Daphne De Groot, Stephan H Schirmer, Liesbeth H. P. Hekking, Bernard M Van Den Berg, Niels Van Royen, Jan A. Post, Hans Vink, Marius Giorgian Ionita, Martin MoserAbstract:During collateral artery growth, monocytes adhere to the endothelium and secrete cytokines from the perivascular space promoting arteriogenesis. Recently, the endothelial Glycocalyx has been shown to modulate leucocyte infiltration in atherogenic regions. The role of this endothelial surface coating in arteriogenesis, however, has not been investigated so far. We now report that local plasma levels of hyaluronic acid are specifically increased in collateral arterial blood of coronary artery disease patients and hypothesized that components of the endothelial Glycocalyx are shed during arteriogenesis, resulting in decreased Glycocalyx dimensions and an increased leucocyte extravasation. In a rabbit model of femoral artery ligation, electron microscopy revealed a decrease in Glycocalyx dimensions in collateral arteries compared with quiescent anastomoses (67.5 ± 47.2 nm versus 101.0 ± 11.3 nm; P < 0.001). This decrease was correlated with a higher number of perivascular macrophages around collateral arteries. The additional Glycocalyx perturbation by local hyaluronidase infusion almost completely removed the endothelial surface layer and temporarily stimulated leucocyte accumulation in the perivascular space. However, complete perturbation of the Glycocalyx by hyaluronidase infusion resulted in a significant attenuation of collateral artery growth assessed by microsphere-based perfusion measurements (ml/min/100 mmHg: hyaluronidase: 27.5 ± 3.5; Controls: 47.1 ± 3.83; P < 0.001) and a lower percentage of actively proliferating vascular smooth muscle cells. A decreased expression of the shear-stress regulated pro-arteriogenic genes eNOS and TGF-β1 suggests an impaired mechanotransduction as the underlying mechanisms. For the first time, we describe the role of the endothelial Glycocalyx in collateral artery growth. Although complete abrogation led to attenuated arteriogenesis, shedding of Glycocalyx components is observed during collateral artery growth.
John M. Tarbell - One of the best experts on this subject based on the ideXlab platform.
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The Glycocalyx and Its Role in Vascular Physiology and Vascular Related Diseases
Cardiovascular Engineering and Technology, 2020Co-Authors: Sheldon Weinbaum, Limary M. Cancel, Bingmei M. Fu, John M. TarbellAbstract:Purpose In 2007 the two senior authors wrote a review on the structure and function of the endothelial Glycocalyx layer (Weinbaum in Annu Rev Biomed Eng 9:121–167, 2007). Since then there has been an explosion of interest in this hydrated gel-like structure that coats the luminal surface of endothelial cells that line our vasculature due to its important functions in (A) basic vascular physiology and (B) vascular related diseases. This review will highlight the major advances that have occurred since our 2007 paper. Methods A literature search mainly focusing on the role of the Glycocalyx in the two major areas described above was performed using electronic databases. Results In part (A) of this review, the new formulation of the century old Starling principle, now referred to as the Michel–Weinbaum glycoclayx model or revised Starling hypothesis, is described including new subtleties and physiological ramifications. New insights into mechanotransduction and release of nitric oxide due to fluid shear stress sensed by the Glycocalyx are elaborated. Major advances in understanding the organization and function of Glycocalyx components, and new techniques for measuring both its thickness and spatio-chemical organization based on super resolution, stochastic optical reconstruction microscopy (STORM) are presented. As discussed in part (B) of this review, it is now recognized that artery wall stiffness associated with hypertension and aging induces Glycocalyx degradation, endothelial dysfunction and vascular disease. In addition to atherosclerosis and cardiovascular diseases, the Glycocalyx plays an important role in lifestyle related diseases (e.g., diabetes) and cancer. Infectious diseases including sepsis, Dengue, Zika and Corona viruses, and malaria also involve the Glycocalyx. Because of increasing recognition of the role of the Glycocalyx in a wide range of diseases, there has been a vigorous search for methods to protect the Glycocalyx from degradation or to enhance its synthesis in disease environments. Conclusion As we have seen in this review, many important developments in our basic understanding of GCX structure, function and role in diseases have been described since the 2007 paper. The future is wide open for continued GCX research.
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The Glycocalyx and its significance in human medicine
Journal of Internal Medicine, 2016Co-Authors: John M. Tarbell, Limary M. CancelAbstract:Cells are covered by a surface layer of glycans that is referred to as the 'Glycocalyx'. In this review, we focus on the role of the Glycocalyx in vascular diseases (atherosclerosis, stroke, hypertension, kidney disease and sepsis) and cancer. The Glycocalyx and its principal glycosaminoglycans [heparan sulphate (HS) and hyaluronic acid (HA)] and core proteins (syndecans and glypicans) are degraded in vascular diseases, leading to a breakdown of the vascular permeability barrier, enhanced access of leucocytes to the arterial intima that propagate inflammation and alteration of endothelial mechanotransduction mechanisms that protect against disease. By contrast, the Glycocalyx on cancer cells is generally robust, promoting integrin clustering and growth factor signalling, and mechanotransduction of interstitial flow shear stress that is elevated in tumours to upregulate matrix metalloproteinase release which enhances cell motility and metastasis. HS and HA are consistently elevated on cancer cells and are associated with tumour growth and metastasis. Later, we will review the agents that might be used to enhance or protect the Glycocalyx to combat vascular disease, as well as a different set of compounds that can degrade the cancer cell Glycocalyx to suppress cell growth and metastasis. It is clear that what is beneficial for either vascular disease or cancer will not be so for the other. The overarching conclusions are that (i) the importance of the Glycocalyx in human medicine is only beginning to be recognized, and (ii) more detailed studies of Glycocalyx involvement in vascular diseases and cancer will lead to novel treatment modalities.
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sphingosine 1 phosphate protects endothelial Glycocalyx by inhibiting syndecan 1 shedding
American Journal of Physiology-heart and Circulatory Physiology, 2014Co-Authors: Ye Zeng, R H Adamson, F E Curry, John M. TarbellAbstract:Endothelial cells (ECs) are covered by a surface Glycocalyx layer that forms part of the barrier and mechanosensing functions of the blood-tissue interface. Removal of albumin in bathing media induces collapse or shedding of the Glycocalyx. The electrostatic interaction between arginine residues on albumin, and negatively charged glycosaminoglycans (GAGs) in the Glycocalyx have been hypothesized to stabilize the Glycocalyx structure. Because albumin is one of the primary carriers of the phospholipid sphingosine-1-phosphate (S1P), we evaluated the alternate hypothesis that S1P, acting via S1P1 receptors, plays the primary role in stabilizing the endothelial Glycocalyx. Using confocal microscopy on rat fat-pad ECs, we demonstrated that heparan sulfate (HS), chondroitin sulfate (CS), and ectodomain of syndecan-1 were shed from the endothelial cell surface after removal of plasma protein but were retained in the presence of S1P at concentrations of >100 nM. S1P1 receptor antagonism abolished the protection of the Glycocalyx by S1P and plasma proteins. S1P reduced GAGs released after removal of plasma protein. The mechanism of protection from loss of Glycocalyx components by S1P-dependent pathways was shown to be suppression of metalloproteinase (MMP) activity. General inhibition of MMPs protected against loss of CS and syndecan-1. Specific inhibition of MMP-9 and MMP-13 protected against CS loss. We conclude that S1P plays a critical role in protecting the Glycocalyx via S1P1 and inhibits the protease activity-dependent shedding of CS, HS, and the syndecan-1 ectodomain. Our results provide new insight into the role for S1P in protecting the Glycocalyx and maintaining vascular homeostasis.
Leonhard Mockl - One of the best experts on this subject based on the ideXlab platform.
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the emerging role of the mammalian Glycocalyx in functional membrane organization and immune system regulation
Frontiers in Cell and Developmental Biology, 2020Co-Authors: Leonhard MocklAbstract:All cells in the human body are covered by a dense layer of sugars and the proteins and lipids to which they are attached, collectively termed the "Glycocalyx". For decades, the organization of the Glycocalyx and its interplay with the cellular state have remained enigmatic. This changed in recent years. Latest research has shown that the Glycocalyx is an organelle of vital significance, actively involved in and functionally relevant for various cellular processes, that can be directly targeted in therapeutic contexts. This review gives a brief introduction into Glycocalyx biology and describes the specific challenges Glycocalyx research faces. Then, the traditional view of the role of the Glycocalyx is discussed before several recent breakthroughs in Glycocalyx research are surveyed. These results exemplify a currently unfolding bigger picture about the role of the Glycocalyx as a fundamental cellular agent.
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Quantitative Super-Resolution Microscopy of the Mammalian Glycocalyx.
Developmental Cell, 2019Co-Authors: Leonhard Mockl, Kayvon Pedram, Anish R. Roy, Venkatesh Krishnan, Anna-karin Gustavsson, Oliver Dorigo, Carolyn R. Bertozzi, W. E. MoernerAbstract:Summary The mammalian Glycocalyx is a heavily glycosylated extramembrane compartment found on nearly every cell. Despite its relevance in both health and disease, studies of the Glycocalyx remain hampered by a paucity of methods to spatially classify its components. We combine metabolic labeling, bioorthogonal chemistry, and super-resolution localization microscopy to image two constituents of cell-surface glycans, N-acetylgalactosamine (GalNAc) and sialic acid, with 10–20 nm precision in 2D and 3D. This approach enables two measurements: Glycocalyx height and the distribution of individual sugars distal from the membrane. These measurements show that the Glycocalyx exhibits nanoscale organization on both cell lines and primary human tumor cells. Additionally, we observe enhanced Glycocalyx height in response to epithelial-to-mesenchymal transition and to oncogenic KRAS activation. In the latter case, we trace increased height to an effector gene, GALNT7. These data highlight the power of advanced imaging methods to provide molecular and functional insights into Glycocalyx biology.
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Invasiveness of Cells Leads to Changes in Their Interaction Behavior with the Glycocalyx
Advanced Biosystems, 2018Co-Authors: Ellen Broda, Leonhard Mockl, Adriano A. Torrano, Laura Löbbert, Christoph Bräuchle, Hanna EngelkeAbstract:Transendothelial migration is a crucial step during metastasis. Before circulating tumor cells enter the endothelium, they face the Glycocalyx. While invasive migration of cancer cells is well studied, few investigations exist regarding their interaction with the Glycocalyx. Here, the interaction of three breast cell lines with an endothelial Glycocalyx is studied. Benign MCF-10A, noninvasive malign MCF-7, and invasive MDA-MB-231 cells penetrate the Glycocalyx, just adhere to it or approach without even attaching to it. Remarkable fluctuations in these interaction modes are detected by time-resolved interaction profiles. Adhesion, migration, and invasion characteristics as well as combinations of interaction modes, cell shapes, and cell extensions are studied. The motility and penetration depth into the Glycocalyx are analyzed. The invasive cells are the most flexible, penetrating the Glycocalyx mostly with a round shape and feet-like membrane extensions. Noninvasive cancer cells penetrate the Glycocalyx the deepest over time and benign cells integrate more likely into the endothelial cell layer underneath the Glycocalyx.
Max Nieuwdorp - One of the best experts on this subject based on the ideXlab platform.
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effect of sulodexide on endothelial Glycocalyx and vascular permeability in patients with type 2 diabetes mellitus
Diabetologia, 2010Co-Authors: Lysette N Broekhuizen, Erik S.g. Stroes, Max Nieuwdorp, Bregtje A Lemkes, Hans L Mooij, Marijn C Meuwese, H J Verberne, F Holleman, Reinier O Schlingemann, Hans VinkAbstract:Aims/hypothesis Endothelial Glycocalyx perturbation contributes to increased vascular permeability. In the present study we set out to evaluate whether: (1) Glycocalyx is perturbed in individuals with type 2 diabetes mellitus, and (2) oral Glycocalyx precursor treatment improves Glycocalyx properties.
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Sickle cell patients are characterized by a reduced Glycocalyx volume
Haematologica, 2008Co-Authors: Eduard J. Van Beers, Max Nieuwdorp, Ashley J. Duits, Ludo M. Evers, John-john B. Schnog, Bart J. BiemondAbstract:The Glycocalyx is an important anti-inflammatory and anti-adhesive barrier at the luminal side of endothelial cells. Glycocalyx volume was significantly reduced in sickle cell patients (HbSS/HbSβ–tha-lassemia median 0.47L, IQR 0.27–0.66, HbSC/HbSβ+-thalassemia 0.23L, 0.0–0.58) compared with controls (1×109L, 0.52–1.77) ( p =0.03). Reduced Glycocalyx may be a new factor in the pathophysiology of sickle cell disease.
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vasculoprotective properties of the endothelial Glycocalyx effects of fluid shear stress
Journal of Internal Medicine, 2006Co-Authors: Mirella Gouverneur, B Berg, Erik S.g. Stroes, Max Nieuwdorp, Hans VinkAbstract:The endothelial Glycocalyx exerts a wide array of vasculoprotective effects via inhibition of coagulation and leucocyte adhesion, by contributing to the vascular permeability barrier and by mediating shear stress-induced NO release. In this review, we will focus on the relationship between fluid shear stress and the endothelial Glycocalyx. We will address the hypothesis that modulation of Glycocalyx synthesis by fluid shear stress may contribute to thinner glycocalyces, and therefore more vulnerable endothelium, at lesion-prone sites of arterial bifurcations. Finally, we will discuss the effects of known atherogenic stimuli such as hyperglycaemia on whole body Glycocalyx volume in humans and its effect on endothelial function
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Endothelial Glycocalyx Damage Coincides With Microalbuminuria in Type 1 Diabetes
Diabetes, 2006Co-Authors: Max Nieuwdorp, Hans L Mooij, Jojanneke Kroon, Bektaş Atasever, Jos A. E. Spaan, Can Ince, Frits Holleman, Michaela Diamant, Robert J. Heine, Joost B.l. HoekstraAbstract:Chronic hyperglycemia underlies microvascular complications in patients with type 1 diabetes. The mechanisms leading to these vascular complications are not fully understood. Recently, we observed that acute hyperglycemia results in endothelial Glycocalyx damage. To establish whether Glycocalyx is associated with microvascular damage, we performed Glycocalyx perturbation volume measurements in type 1 diabetic patients with microalbuminuria (DM1-MA group; n = 7), without microalbuminuria (DM1-NA group; n = 7), and in age-matched control subjects (CON; n = 7). Systemic Glycocalyx volume was determined comparing intravascular distribution volume of a Glycocalyx-permeable tracer (dextran 40) to that of a Glycocalyx-impermeable tracer (labeled erythrocytes). Sublingual capillaries were visualized using orthogonal polarization spectral microscopy to estimate microvascular Glycocalyx. Patients and control subjects were matched according to age and BMI. Glycocalyx volume decreased in a stepwise fashion from CON, DM1-NA, and finally DM1-MA subjects (1.5 ± 0.1, 0.8 ± 0.4, and 0.2 ± 0.1 l, respectively, P P
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loss of endothelial Glycocalyx during acute hyperglycemia coincides with endothelial dysfunction and coagulation activation in vivo
Diabetes, 2006Co-Authors: Max Nieuwdorp, Mirella Gouverneur, Hans L Mooij, Frits Holleman, Joost B.l. Hoekstra, Timon W Van Haeften, Miriam H P Van Lieshout, Marcel Levi, Joost C M Meijers, Hans VinkAbstract:Hyperglycemia is associated with increased susceptibility to atherothrombotic stimuli. The Glycocalyx, a layer of proteoglycans covering the endothelium, is involved in the protective capacity of the vessel wall. We therefore evaluated whether hyperglycemia affects the Glycocalyx, thereby increasing vascular vulnerability. The systemic Glycocalyx volume was estimated by comparing the distribution volume of a Glycocalyx permeable tracer (dextran 40) with that of a Glycocalyx impermeable tracer (labeled erythrocytes) in 10 healthy male subjects. Measurements were performed in random order on five occasions: two control measurements, two measurements during normoinsulinemic hyperglycemia with or without N-acetylcysteine (NAC) infusion, and one during mannitol infusion. Glycocalyx measurements were reproducible (1.7 +/- 0.2 vs. 1.7 +/- 0.3 l). Hyperglycemia reduced Glycocalyx volume (to 0.8 +/- 0.2 l; P < 0.05), and NAC was able to prevent the reduction (1.4 +/- 0.2 l). Mannitol infusion had no effect on Glycocalyx volume (1.6 +/- 0.1 l). Hyperglycemia resulted in endothelial dysfunction, increased plasma hyaluronan levels (from 70 +/- 6 to 112 +/- 16 ng/ml; P < 0.05) and coagulation activation (prothrombin activation fragment 1 + 2: from 0.4 +/- 0.1 to 1.1 +/- 0.2 nmol/l; d-dimer: from 0.27 +/- 0.1 to 0.55 +/- 0.2 g/l; P < 0.05). Taken together, these data indicate a potential role for Glycocalyx perturbation in mediating vascular dysfunction during hyperglycemia.
Bernhard F. Becker - One of the best experts on this subject based on the ideXlab platform.
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Placental syncytiotrophoblast maintains a specific type of Glycocalyx at the fetomaternal border: the Glycocalyx at the fetomaternal interface in healthy women and patients with HELLP syndrome.
Reproductive Sciences, 2013Co-Authors: Klaus Hofmann-kiefer, Daniel Chappell, Julia Knabl, Hans-georg Frank, Nadja Martinoff, Peter Conzen, Bernhard F. Becker, Markus RehmAbstract:Recent studies showed that considerable amounts of glycosaminoglycans are released into maternal blood during normal pregnancy and in hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome. Maternal endothelia and the syncytiotrophoblast layer have been discussed as a possible origin of these Glycocalyx components. Our study aimed to visualize the Glycocalyx on the syncytiotrophoblast by electron microscopy, to analyze its structure and composition by immunohistochemistry, and to determine potential differences between healthy women and women with HELLP syndrome. For electron microscopy, a cotyledon was fixed by perfusion of the intervillous space with a 2% lanthanum–nitrate glutaraldehyde solution followed by immersion fixation in the same fixative. For immunohistochemistry, sections of 16 placentas (HELLP patients/healthy women, n = 8 each) were stained with monoclonal antibodies against the main Glycocalyx constituents syndecan 1, hyaluronic acid, and heparan sulfate. Semiquantitative evaluation of staining intensity focused on the apical surface of the syncytiotrophoblast and fetal intravillous endothelia as possible localizations of a placental Glycocalyx. Electron microscopy revealed a Glycocalyx of approximately 250 nm, covering the syncytiotrophoblast layer. This was found to contain large amounts of syndecan 1, but neither hyaluronic acid nor heparan sulfate as major components. Intravillous fetal endothelium did not express any of the investigated glycosaminoglycans. Healthy women and patients with HELLP showed no differences concerning Glycocalyx composition and thickness of the syncytiotrophoblast. The composition of the “placental” Glycocalyx differs from the adult and fetal vascular Glycocalyx. Obviously, the human placental syncytiotrophoblast maintains a special kind of Glycocalyx at the fetomaternal interface.
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antithrombin reduces shedding of the endothelial Glycocalyx following ischaemia reperfusion
Cardiovascular Research, 2009Co-Authors: Daniel Chappell, Peter Conzen, Markus Rehm, Matthias Jacob, K Hofmannkiefer, Ulrich Welsch, Bernhard F. BeckerAbstract:Aims Antithrombin is an important inhibitor of the coagulation system, additionally exerting specific anti-inflammatory effects on endothelial cells. Healthy vascular endothelium is coated by the endothelial Glycocalyx, diminution of which increases capillary permeability, e.g. after ischaemia. Antithrombin is known to infiltrate the Glycocalyx, binding to glycosaminoglycans, and to preserve the Glycocalyx after application tumour necrosis factor-α. We investigated the influence of antithrombin on Glycocalyx subjected to ischaemia/reperfusion. Methods and results Isolated guinea pig hearts were perfused with Krebs–Henseleit buffer (KHB). Antithrombin was applied to achieve physiological levels (1 U/mL) before inducing 20 min of ischaemia (37°C). Hearts were reperfused for 20 min at constant flow (baseline perfusion pressure 70 cmH2O) with KHB or KHB plus 2 g% hydroxyethyl starch (130 kDa). Coronary net fluid filtration was assessed directly by measuring transudate formation on the epicardial surface. Post-ischaemic coronary release of syndecan-1 and heparan sulfate was quantified by ELISA. Hearts were perfusion-fixed to visualize the Glycocalyx by electron microscopy. Ischaemia/reperfusion caused degradation of the Glycocalyx, enhanced coronary perfusion pressure, and increased vascular permeability. Antithrombin significantly reduced post-ischaemic Glycocalyx shedding, coronary perfusion pressure, coronary leak, and tissue oedema formation compared to untreated hearts. Additional application of colloid augmented these actions of antithrombin. Electron microscopy revealed a mostly intact Glycocalyx after antithrombin treatment. Conclusion Antithrombin preserves the endothelial Glycocalyx, sustaining the vascular barrier function and reducing interstitial oedema. The potentiated effect of colloid in these hearts suggests that the prevention of shedding should be of functional benefit also in vivo .
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the Glycocalyx of the human umbilical vein endothelial cell an impressive structure ex vivo but not in culture
Circulation Research, 2009Co-Authors: Daniel Chappell, Peter Conzen, Markus Rehm, Matthias Jacob, Ulrich Welsch, Oliver Paul, Mechthild Stoeckelhuber, Bernhard F. BeckerAbstract:Potter and Damiano recently assessed the hydrodynamic dimensions of the endothelial Glycocalyx in vivo (mouse cremaster muscle venules) and in vitro (human umbilical vein and bovine aorta endothelium cultured in perfused microchannels) using fluorescent microparticle image velocimetry ( Circ Res . 2008;102:770–776). Great discrepancy was observed, the Glycocalyx presenting a zone of interaction extending ≈0.52 μm into the vessel lumen in vivo, but only 0.02 to 0.03 μm from cultured cells. In an accompanying editorial, Barakat cautioned that the difference in hydrodynamic interaction did not allow one to conclude that the cultured cells totally lack a physical cell surface layer capable of mechanotransduction ( Circ Res . 2008;102:747–748). To stabilize the Glycocalyx for electron microscopic investigation, we perfusion-fixed 6 human umbilical veins and confluent and nonconfluent cultures (5 each) of human umbilical vein endothelial cells (HUVECs) with lanthanum/glutaraldehyde solution. Ex vivo, the thickness of Glycocalyx of umbilical vein endothelium averaged 878 nm. HUVECs in vitro presented a Glycocalyx with a dense-zone thickness of only 29.4 nm, plus sparse filaments reaching out on average to 118 nm, there being no difference between the nonconfluent and confluent cells. Immunohistology demonstrated the presence of heparan sulfates and syndecan-1, main constituents of the Glycocalyx, both ex vivo and in vitro. These results support the observed discrepancy between Glycocalyx thickness in vivo and in vitro, now for one and the same type of human cell. The presence of heparan sulfates and syndecan-1 also on cultured cells may explain why mechanotransduction phenomena can be observed even with a nonmature Glycocalyx.