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Wang Y, Liu ZS, Wang ZB, Liu S, Sun FB. Efficacy of laparoscopic low anterior resection for colorectal cancer patients with 3D-vascular reconstruction for left coronary artery preservation. World J Gastrointest Surg 2024; 16:1548-1557. [PMID: 38983331 PMCID: PMC11230005 DOI: 10.4240/wjgs.v16.i6.1548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 05/13/2024] [Accepted: 05/22/2024] [Indexed: 06/27/2024] Open
Abstract
BACKGROUND Laparoscopic low anterior resection (LLAR) has become a mainstream surgical method for the treatment of colorectal cancer, which has shown many advantages in the aspects of surgical trauma and postoperative rehabilitation. However, the effect of surgery on patients' left coronary artery and its vascular reconstruction have not been deeply discussed. With the development of medical imaging technology, 3D vascular reconstruction has become an effective means to evaluate the curative effect of surgery. AIM To investigate the clinical value of preoperative 3D vascular reconstruction in LLAR of rectal cancer with the left colic artery (LCA) preserved. METHODS A retrospective cohort study was performed to analyze the clinical data of 146 patients who underwent LLAR for rectal cancer with LCA preservation from January to December 2023 in our hospital. All patients underwent LLAR of rectal cancer with the LCA preserved, and the intraoperative and postoperative data were complete. The patients were divided into a reconstruction group (72 patients) and a nonreconstruction group (74 patients) according to whether 3D vascular reconstruction was performed before surgery. The clinical features, operation conditions, complications, pathological results and postoperative recovery of the two groups were collected and compared. RESULTS A total of 146 patients with rectal cancer were included in the study, including 72 patients in the reconstruction group and 74 patients in the nonreconstruction group. There were 47 males and 25 females in the reconstruction group, aged (59.75 ± 6.2) years, with a body mass index (BMI) (24.1 ± 2.2) kg/m2, and 51 males and 23 females in the nonreconstruction group, aged (58.77 ± 6.1) years, with a BMI (23.6 ± 2.7) kg/m2. There was no significant difference in the baseline data between the two groups (P > 0.05). In the submesenteric artery reconstruction group, 35 patients were type I, 25 patients were type II, 11 patients were type III, and 1 patient was type IV. There were 37 type I patients, 24 type II patients, 12 type III patients, and 1 type IV patient in the nonreconstruction group. There was no significant difference in arterial typing between the two groups (P > 0.05). The operation time of the reconstruction group was 162.2 ± 10.8 min, and that of the nonreconstruction group was 197.9 ± 19.1 min. Compared with that of the reconstruction group, the operation time of the two groups was shorter, and the difference was statistically significant (t = 13.840, P < 0.05). The amount of intraoperative blood loss was 30.4 ± 20.0 mL in the reconstruction group and 61.2 ± 26.4 mL in the nonreconstruction group. The amount of blood loss in the reconstruction group was less than that in the control group, and the difference was statistically significant (t = -7.930, P < 0.05). The rates of anastomotic leakage (1.4% vs 1.4%, P = 0.984), anastomotic hemorrhage (2.8% vs 4.1%, P = 0.672), and postoperative hospital stay (6.8 ± 0.7 d vs 7.0 ± 0.7 d, P = 0.141) were not significantly different between the two groups. CONCLUSION Preoperative 3D vascular reconstruction technology can shorten the operation time and reduce the amount of intraoperative blood loss. Preoperative 3D vascular reconstruction is recommended to provide an intraoperative reference for laparoscopic low anterior resection with LCA preservation.
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Affiliation(s)
- Ye Wang
- Department of General Surgery, Qingdao Hiser Hospital Affiliated of Qingdao University (Qingdao Traditional Chinese Medicine Hospital), Qingdao 266033, Shandong Province, China
| | - Zhi-Sheng Liu
- Department of General Surgery, Qingdao Hiser Hospital Affiliated of Qingdao University (Qingdao Traditional Chinese Medicine Hospital), Qingdao 266033, Shandong Province, China
| | - Zong-Bao Wang
- Department of General Surgery, Qingdao Hiser Hospital Affiliated of Qingdao University (Qingdao Traditional Chinese Medicine Hospital), Qingdao 266033, Shandong Province, China
| | - Shawn Liu
- Department of Gastrointestinal Surgery, National University Hospital of Singapore, Singapore 119228, Singapore
| | - Feng-Bo Sun
- Department of General Surgery, Qingdao Hiser Hospital Affiliated of Qingdao University (Qingdao Traditional Chinese Medicine Hospital), Qingdao 266033, Shandong Province, China
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Ermert K, Buhl EM, Klinkhammer BM, Floege J, Boor P. Reduction of Endothelial Glycocalyx on Peritubular Capillaries in Chronic Kidney Disease. THE AMERICAN JOURNAL OF PATHOLOGY 2023; 193:138-147. [PMID: 36414084 DOI: 10.1016/j.ajpath.2022.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 10/07/2022] [Accepted: 11/03/2022] [Indexed: 11/20/2022]
Abstract
In chronic kidney disease (CKD), peritubular capillaries undergo anatomic and functional alterations, such as rarefaction and increased permeability. The endothelial glycocalyx (EG) is a carbohydrate-rich gel-like mesh, which covers the luminal surface of endothelial cells. It is involved in many regulatory functions of the endothelium, including vascular permeability. Herein, we investigated ultrastructural alterations of the EG in different murine CKD models. Fluorescence staining using different lectins with high affinity to components of the renal glycocalyx revealed a reduced binding to the endothelium in CKD in the animal models, and there were similar finding in human kidney specimens. Lanthanum Dysprosium Glycosamino Glycan adhesion staining technique was used to visualize the ultrastructure of the glycocalyx in transmission electron microscopy. This also enabled quantitative analyses, showing a significant reduction of the EG thickness and density. In addition, mRNA expression of proteins involved in glycocalyx biology, synthesis, and turnover (ie, syndecan 1 and glypican 1), which are main components of the glycocalyx, and exostosin 2, involved in the synthesis of the glycocalyx, were significantly up-regulated in endothelial cells isolated from murine CKD models. Visualization of glycocalyx using specific transmission electron microscopy analyses allows qualitative and quantitative analyses and revealed significant pathologic alterations in peritubular capillaries in CKD.
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Affiliation(s)
- Katja Ermert
- Institute of Pathology, RWTH Aachen University Hospital, Aachen, Germany; Division of Nephrology and Immunology, RWTH Aachen University Hospital, Aachen, Germany
| | - Eva M Buhl
- Institute of Pathology, RWTH Aachen University Hospital, Aachen, Germany; Division of Nephrology and Immunology, RWTH Aachen University Hospital, Aachen, Germany; Electron Microscopy Facility, RWTH Aachen University Hospital, Aachen, Germany
| | - Barbara M Klinkhammer
- Institute of Pathology, RWTH Aachen University Hospital, Aachen, Germany; Division of Nephrology and Immunology, RWTH Aachen University Hospital, Aachen, Germany
| | - Jürgen Floege
- Division of Nephrology and Immunology, RWTH Aachen University Hospital, Aachen, Germany
| | - Peter Boor
- Institute of Pathology, RWTH Aachen University Hospital, Aachen, Germany; Division of Nephrology and Immunology, RWTH Aachen University Hospital, Aachen, Germany; Electron Microscopy Facility, RWTH Aachen University Hospital, Aachen, Germany.
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Chevalier L, Selim J, Castro C, Cuvilly F, Baste JM, Richard V, Pareige P, Bellien J. Combined Electron Microscopy Approaches for Arterial Glycocalyx Visualization. Front Cardiovasc Med 2022; 9:840689. [PMID: 35355969 PMCID: PMC8959549 DOI: 10.3389/fcvm.2022.840689] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 02/07/2022] [Indexed: 11/13/2022] Open
Abstract
Mainly constituted of glycosaminoglycans and proteoglycans, the glycocalyx is anchored in the plasma membrane, covering, in particular, the extracellular face of the arterial endothelium. Due to its complex three-dimensional (3D) architecture, the glycocalyx interacts with a wide variety of proteins, contributing to vascular permeability, the flow of mechanotransduction, and the modulation of local inflammatory processes. Alterations of glycocalyx structure mediate the endothelial dysfunction and contribute to the aggravation of peripheral vascular diseases. Therefore, the exploration of its ultrastructure becomes a priority to evaluate the degree of injury under physiopathological conditions and to assess the impact of therapeutic approaches. The objective of this study was to develop innovative approaches in electron microscopy to visualize the glycocalyx at the subcellular scale. Intravenous perfusion on rats with a fixing solution containing aldehyde fixatives enriched with lanthanum ions was performed to prepare arterial samples. The addition of lanthanum nitrate in the fixing solution allowed the enhancement of the staining of the glycocalyx for transmission electron microscopy (TEM) and to detect elastic and inelastic scattered electrons, providing complementary qualitative information. The strength of scanning electron microscopy (SEM) was used on resin-embedded serial sections, allowing rapid and efficient large field imaging and previous correlative TEM observations for ultrastructural fine details. To demonstrate the dynamic feature of the glycocalyx, 3D tomography was provided by dual-beam focus-ion-beam-SEM (FIB-SEM). These approaches allowed us to visualize and characterize the ultrastructure of the pulmonary artery glycocalyx under physiological conditions and in a rat pulmonary ischemia-reperfusion model, known to induce endothelial dysfunction. This study demonstrates the feasibility of combined SEM, TEM, and FIB-SEM tomography approaches on the same sample as the multiscale visualization and the identification of structural indicators of arterial endothelial glycocalyx integrity.
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Affiliation(s)
- Laurence Chevalier
- Université Rouen Normandie, CNRS, INSA Rouen Normandie- Normandie Université- GPM-UMR 6634, Rouen, France
- *Correspondence: Laurence Chevalier
| | - Jean Selim
- Université Rouen Normandie, INSERM, Normandie Université, ENVI- U1096, Rouen, France
- Rouen University Hospital, Department of Anaesthesia and Critical Care, Rouen, France
| | - Celia Castro
- Université Rouen Normandie, CNRS, INSA Rouen Normandie- Normandie Université- GPM-UMR 6634, Rouen, France
| | - Fabien Cuvilly
- Université Rouen Normandie, CNRS, INSA Rouen Normandie- Normandie Université- GPM-UMR 6634, Rouen, France
| | - Jean-Marc Baste
- Université Rouen Normandie, INSERM, Normandie Université, ENVI- U1096, Rouen, France
- Rouen University Hospital, Department of Thoracic Surgery, Rouen, France
| | - Vincent Richard
- Université Rouen Normandie, INSERM, Normandie Université, ENVI- U1096, Rouen, France
- Rouen University Hospital, Department of Pharmacology, Rouen, France
| | - Philippe Pareige
- Université Rouen Normandie, CNRS, INSA Rouen Normandie- Normandie Université- GPM-UMR 6634, Rouen, France
| | - Jeremy Bellien
- Université Rouen Normandie, INSERM, Normandie Université, ENVI- U1096, Rouen, France
- Rouen University Hospital, Department of Pharmacology, Rouen, France
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Nizamundeen ZA, ElSaboni L, Vetch G, Karim J, Neal CR, Allen CL, Bates DO, Arkill KP. Transmission Electron Microscopy of Endothelium. Methods Mol Biol 2022; 2441:95-103. [PMID: 35099731 DOI: 10.1007/978-1-0716-2059-5_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Transmission electron microscopy using resin sections still remains an exceptionally useful tool in evaluating cellular ultrastucture within tissue. For the endothelium the best method for maintaining such structure is perfusion fixation: fixing the tissue under physiological pressure. Here the focus is on a method of maintaining the vascular wall structure including the endothelial glycocalyx and extending this with tilt series tomography. Shown are typical histological sections from multiple capillary beds including brain, heart and retina using a lanthanide staining technique (LaDy GAGa) to highlight that the differences in normo-physiology are substantial.It is hoped that users will find the notes useful in deciding which specific staining and imaging method would suit their needs so this technically challenging, and low throughput methodology, is used to its best effect.
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Affiliation(s)
- Zubair Ahmed Nizamundeen
- Tumour and Vascular Biology Laboratories, Centre for Cancer Sciences, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham, UK
| | - Loubna ElSaboni
- Tumour and Vascular Biology Laboratories, Centre for Cancer Sciences, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham, UK
| | - Grace Vetch
- Tumour and Vascular Biology Laboratories, Centre for Cancer Sciences, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham, UK
| | - Jumana Karim
- Tumour and Vascular Biology Laboratories, Centre for Cancer Sciences, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham, UK
| | - Chris R Neal
- Wolfson BioImaging, Biomedical Sciences, University of Bristol, Bristol, UK
| | | | - David O Bates
- Tumour and Vascular Biology Laboratories, Centre for Cancer Sciences, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham, UK
| | - Kenton P Arkill
- Tumour and Vascular Biology Laboratories, Centre for Cancer Sciences, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham, UK.
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Arkill KP. A Reinterpretation of Evidence for the Endothelial Glycocalyx Filtration Structure. Front Cell Dev Biol 2021; 9:734661. [PMID: 34540847 PMCID: PMC8442954 DOI: 10.3389/fcell.2021.734661] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 08/13/2021] [Indexed: 11/17/2022] Open
Abstract
The endothelial glycocalyx (eGlx) is thought to be the primary macromolecular filter for fluid flux out of the vasculature. This filter maintains the higher protein concentration within the vessel lumen relative to the tissue. Whilst the arguments for the eGlx being the size filter are convincing the structural evidence has been limited to specialized stains of perfusion fixed tissue, which are further processed for resin embedding for transmission electron microscopy. The staining and processing of the delicate pore structure has left many researchers struggling to interpret the observed surface coat. Previous work has alluded to a 19.5 nm spacing between fibers; however, whilst repeatable it does not give an eGlx pore size consistent with known glycosaminoglycan (GAG) molecular structure due to the required fiber thickness of >10 nm. Here a new interpretation is proposed based on the likelihood that the electron micrographs of are often of collapsed eGlx. The 19.5 nm spacing measured may therefore be the core protein of the proteoglycans (PGs) with the GAGs wrapped up around them rather than in an expanded in vivo state. The concept is explored to determine that this is indeed consistent with experimental measurements of permeability if the syndecans are predominately dimerized. Further an alteration of core protein lattice from hexagonal packing to square packing dramatically changes the permeability which could be facilitated via known mechanisms such as transient actin binding.
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Affiliation(s)
- Kenton P. Arkill
- School of Medicine, University of Nottingham Biodiscovery Institute, University Park, Nottingham, United Kingdom
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Hempel C, Kapishnikov S, Perez-Berna AJ, Werner S, Guttmann P, Pereiro E, Qvortrup K, Andresen TL. The need to freeze-Dehydration during specimen preparation for electron microscopy collapses the endothelial glycocalyx regardless of fixation method. Microcirculation 2020; 27:e12643. [PMID: 32542908 DOI: 10.1111/micc.12643] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 05/25/2020] [Accepted: 06/06/2020] [Indexed: 12/31/2022]
Abstract
OBJECTIVE The endothelial glycocalyx covers the luminal surface of the endothelium and plays key roles in vascular function. Despite its biological importance, ideal visualization techniques are lacking. The current study aimed to improve the preservation and subsequent imaging quality of the endothelial glycocalyx. METHODS In mice, the endothelial glycocalyx was contrasted with a mixture of lanthanum and dysprosium (LaDy). Standard chemical fixation was compared with high-pressure frozen specimens processed with freeze substitution. Also, isolated brain microvessels and cultured endothelial cells were high-pressure frozen and by transmission soft x-rays, imaged under cryogenic conditions. RESULTS The endothelial glycocalyx was in some tissues significantly more voluminous from chemically fixed specimens compared with high-pressure frozen specimens. LaDy labeling introduced excessive absorption contrast, which impeded glycocalyx measurements in isolated brain microvessels when using transmission soft x-rays. In non-contrasted vessels, the glycocalyx was not resolved. LaDy-contrasted, cultured brain endothelial cells allowed to assess glycocalyx volume in vitro. CONCLUSIONS Both chemical and cryogenic fixation followed by dehydration lead to substantial collapse of the glycocalyx. Cryogenic fixation without freeze substitution could be a way forward although transmission soft x-ray tomography based solely on amplitude contrast seems unsuitable.
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Affiliation(s)
- Casper Hempel
- Department of Health Technology, Technical University of Denmark, Lyngby, Denmark.,Centre for Medical Parasitology, Department for Clinical Microbiology, Copenhagen University Hospital, Copenhagen, Denmark.,Department for Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Sergey Kapishnikov
- Department X-Ray microscopy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin, Germany.,Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | | | - Stephan Werner
- Department X-Ray microscopy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin, Germany
| | - Peter Guttmann
- Department X-Ray microscopy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin, Germany
| | - Eva Pereiro
- MISTRAL Beamline-Experiments Division, ALBA Synchrotron Light Source, Barcelona, Spain
| | - Klaus Qvortrup
- Core Facility for Integrated Microscopy (CFIM), University of Copenhagen, Copenhagen, Denmark
| | - Thomas Lars Andresen
- Department of Health Technology, Technical University of Denmark, Lyngby, Denmark
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Curry FE, Michel CC. The endothelial glycocalyx: Barrier functions versus red cell hemodynamics: A model of steady state ultrafiltration through a bi-layer formed by a porous outer layer and more selective membrane-associated inner layer. Biorheology 2020; 56:113-130. [PMID: 30664499 DOI: 10.3233/bir-180198] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Ultrastructural investigations of the endothelial glycocalyx reveal a layer adjacent to the cell surface with a structure consistent with the primary ultrafilter of vascular walls. Theory predicts this layer can be no greater than 200-300 nm thick, a result to be reconciled with observations that red cells and large macromolecules are excluded from a region 1 micrometer or more from the cell membrane. OBJECTIVE To determine whether this apparent inconsistency might be accounted for by a model of steady state water and protein transport through a glycocalyx bi-layer formed by a porous outer layer in series with a more selective inner layer. METHODS Expressions for coupled water and albumin fluxes through the two layers were used to describe steady state ultra-filtration though the bi-layer model. RESULTS Albumin accumulates at the interface between the porous layer and the selective inner layer. The osmotic pressure of accumulated albumin significantly modifies the observed permeability properties of the microvessel wall by an effective unstirred layer effect. CONCLUSIONS The model places significant constraints on the outer layer permeability properties . The only outer layer properties that are consistent with measured steady state filtration rates and models of red cell flux through microvessels are an albumin permeability coefficient and hydraulic conductivity more than an order of magnitude larger than the those of the inner layer.
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Affiliation(s)
- FitzRoy E Curry
- Departments of Physiology and Membrane Biology and Biomedical Engineering, University of California, Davis, USA
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8
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Fan J, Sun Y, Xia Y, Tarbell JM, Fu BM. Endothelial surface glycocalyx (ESG) components and ultra-structure revealed by stochastic optical reconstruction microscopy (STORM). Biorheology 2020; 56:77-88. [PMID: 31045510 DOI: 10.3233/bir-180204] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND In order to play different roles in vascular functions as a mechanosensor to blood flows and as a barrier to transvascular exchange, the endothelial surface glycocalyx (ESG) should have an organized structure. Due to the limitations of optical and electron microscopy, the ultra-structure of ESG has not been revealed until the recent development of super-resolution optical microscopy, STORM. OBJECTIVES To investigate the ESG components and their organization on bEnd3 (mouse brain microvascular endothelial cells) monolayer. METHODS ESG was immunolabeled with anti-heparan sulfate (HS), followed by an ATTO488 conjugated goat anti-mouse IgG, and with biotinylated hyaluronic acid (HA) binding protein, followed by an AF647 conjugated anti-biotin. The ESG was then imaged by the STORM. RESULTS HA is a long molecule weaving into a network which covers the endothelial luminal surface. In contrast, HS is a shorter molecule, perpendicular to the cell surface. HA and HS are partially overlapped with each other at the endothelial luminal surface. We also quantified the length, diameter, orientation, and density of HS at the top, middle and bottom regions of the endothelial surface. CONCLUSIONS Our results suggest that HS plays a major role in mechanosensing and HA plays a major role in the molecular sieve.
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Affiliation(s)
- Jie Fan
- Department of Biomedical Engineering, The City College of the City University of New York, \unskip\break New York, NY, USA
| | - Yi Sun
- Department of Electrical Engineering, The City College of the City University of New York, New York, NY, USA
| | - Yifan Xia
- Department of Biomedical Engineering, The City College of the City University of New York, \unskip\break New York, NY, USA
| | - John M Tarbell
- Department of Biomedical Engineering, The City College of the City University of New York, \unskip\break New York, NY, USA
| | - Bingmei M Fu
- Department of Biomedical Engineering, The City College of the City University of New York, \unskip\break New York, NY, USA
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Sáez P, Gallo D, Morbiducci U. Mechanotransmission of haemodynamic forces by the endothelial glycocalyx in a full-scale arterial model. ROYAL SOCIETY OPEN SCIENCE 2019; 6:190607. [PMID: 31312506 PMCID: PMC6599767 DOI: 10.1098/rsos.190607] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 05/14/2019] [Indexed: 06/10/2023]
Abstract
The glycocalyx has been identified as a key mechano-sensor of the shear forces exerted by streaming blood onto the vascular endothelial lining. Although the biochemical reaction to the blood flow has been extensively studied, the mechanism of transmission of the haemodynamic shear forces to the endothelial transmembrane anchoring structures and, consequently, to the subcellular elements in the cytoskeleton, is still not fully understood. Here we apply a multiscale approach to elucidate how haemodynamic shear forces are transmitted to the transmembrane anchors of endothelial cells. Wall shear stress time histories, as obtained from image-based computational haemodynamics models of a carotid bifurcation, are used as a load and a continuum model is applied to obtain the mechanical response of the glycocalyx all along the cardiac cycle. The main findings of this in silico study are that: (1) the forces transmitted to the transmembrane anchors are in the range of 1-10 pN, which is in the order of magnitude reported for the different conformational states of transmembrane mechanotranductors; (2) locally, the forces transmitted to the anchors of the glycocalyx structure can be markedly different from the near-wall haemodynamic shear forces both in amplitude and frequency content. The findings of this in silico approach warrant future studies focusing on the actual forces transmitted to the transmembrane mechanotransductors, which might outperform haemodynamic descriptors of disturbed shear as localizing factors of vascular disease.
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Affiliation(s)
- P. Sáez
- Laboratori de Càlcul Numèric (LàCaN), Universitat Politècnica de Catalunya, Barcelona, Spain
- Barcelona Graduate School of Mathematics (BGSMath), Barcelona, Spain
| | - D. Gallo
- PoliTo Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Torino, Italy
| | - U. Morbiducci
- PoliTo Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Torino, Italy
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Kofod N, Arppe-Tabbara R, Sørensen TJ. Electronic Energy Levels of Dysprosium(III) ions in Solution. Assigning the Emitting State and the Intraconfigurational 4f–4f Transitions in the Vis–NIR Region and Photophysical Characterization of Dy(III) in Water, Methanol, and Dimethyl Sulfoxide. J Phys Chem A 2019; 123:2734-2744. [DOI: 10.1021/acs.jpca.8b12034] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Nicolaj Kofod
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
| | - Riikka Arppe-Tabbara
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
| | - Thomas Just Sørensen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
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Xia Y, Fu BM. Investigation of Endothelial Surface Glycocalyx Components and Ultrastructure by Single Molecule Localization Microscopy: Stochastic Optical Reconstruction Microscopy (STORM). THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2018; 91:257-266. [PMID: 30258313 PMCID: PMC6153618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/29/2022]
Abstract
On the luminal surface of our blood vessels, there is a thin layer called endothelial surface glycocalyx (ESG) which consists of proteoglycans, glycosaminoglycans (GAGs), and glycoproteins. The GAGs in the ESG are heparan sulfate (HS), hyaluronic acid (HA), chondroitin sulfate (CS), and sialic acid (SA). In order to play important roles in regulating vascular functions, such as being a mechanosensor and transducer for the endothelial cells (ECs) to sense the blood flow, a molecular sieve to maintain normal microvessel permeability and a barrier between the circulating cells and endothelial cells forming the vessel wall, the ESG should have an organized structure at the molecular level. Due to the limitations of conventional optical and electrical microscopy, the ultrastructure of ESG, in the order of 10 to 100 nanometers, has not been revealed until recent development of a super resolution fluorescence optical microscope, Stochastic Optical Reconstruction Microscope (STORM), which is one type of single molecule localization microscopy. This short review describes how the STORM can overcome the diffraction barrier in the conventional fluorescence microscopy to identify the chemical components of the ESG at a high spatial resolution. Examples of the organized ultrastructure of the ESG on the in vitro EC monolayer revealed by the Nikon-STORM system are given as well as how its components get lost during the onset of sepsis, a systemic inflammatory syndrome induced by bacterial infection, which demonstrate that this new technique can be applied to discover the structural and molecular mechanisms at nanometer scales in the native cellular environment for the cellular functions under normal and disease conditions.
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Affiliation(s)
- Yifan Xia
- Department of Biomedical Engineering, The City College of the City University of New York, New York, NY
| | - Bingmei M. Fu
- Department of Biomedical Engineering, The City College of the City University of New York, New York, NY
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Arppe‐Tabbara R, Carro‐Temboury MR, Hempel C, Vosch T, Sørensen TJ. Luminescence from Lanthanide(III) Ions Bound to the Glycocalyx of Chinese Hamster Ovary Cells. Chemistry 2018; 24:11885-11889. [DOI: 10.1002/chem.201802799] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 06/25/2018] [Indexed: 12/26/2022]
Affiliation(s)
- Riikka Arppe‐Tabbara
- Nano-Science Center & Department of ChemistryUniversity of Copenhagen Universitetsparken 5 2100 København Ø Denmark
| | - Miguel R. Carro‐Temboury
- Nano-Science Center & Department of ChemistryUniversity of Copenhagen Universitetsparken 5 2100 København Ø Denmark
| | - Casper Hempel
- Department of Micro- and NanotechnologyTechnical University of Denmark Kgs Lyngby Denmark
| | - Tom Vosch
- Nano-Science Center & Department of ChemistryUniversity of Copenhagen Universitetsparken 5 2100 København Ø Denmark
| | - Thomas Just Sørensen
- Nano-Science Center & Department of ChemistryUniversity of Copenhagen Universitetsparken 5 2100 København Ø Denmark
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Rapoport EM, Matveeva VK, Vokhmyanina OA, Belyanchikov IM, Gabius HJ, Bovin NV. Localization of Galectins within Glycocalyx. BIOCHEMISTRY (MOSCOW) 2018; 83:727-737. [DOI: 10.1134/s000629791806010x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Abstract
This review will highlight our current understanding of the formation, circulation, and immunological role of lymphatic fluid. The formation of the extracellular fluid depends on the net balance between the hydrostatic and osmotic pressure gradients effective in the capillary beds. Lymph originates from the extracellular fluid and its composition combines the ultrafiltrated plasma proteins with the proteome generated by the metabolic activities of each parenchymal tissue. Several analyses have indicated how the lymph composition reflects the organs' physiological and pathological states. The collected lymphatic fluid moves from the capillaries into progressively larger collectors toward the draining lymph node aided by the lymphangion contractility and unidirectional valves, which prevent backflow. The proteomic composition of the lymphatic fluid is reflected in the MHC II peptidome presented by nodal antigen-presenting cells. Taken together, the past few years have generated new interest in the formation, transport, and immunological role of the lymphatic fluid.
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15
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Fu BM. Transport Across the Blood-Brain Barrier. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1097:235-259. [PMID: 30315549 DOI: 10.1007/978-3-319-96445-4_13] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The blood-brain barrier (BBB) is a dynamic barrier essential for maintaining the microenvironment of the brain. Although the special anatomical features of the BBB determine its protective role for the central nervous system (CNS) from blood-borne neurotoxins, however, the BBB extremely limits the therapeutic efficacy of drugs into the CNS, which greatly hinders the treatment of major brain diseases. This chapter summarized the unique structures of the BBB; described a variety of in vivo and in vitro experimental methods for determining the transport properties of the BBB and the permeability of the BBB to water, ions, and solutes including nutrients, therapeutic agents, and drug carriers; and presented recently developed mathematical models which quantitatively correlate the anatomical structures of the BBB with its barrier functions. Recent findings for modulation of the BBB permeability by chemical and physical stimuli were described. Finally, drug delivery strategies through specific trans-BBB routes were discussed.
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Affiliation(s)
- Bingmei M Fu
- Department of Biomedical Engineering, The City College of the City University of New York, New York, NY, USA.
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The Role of Endothelial Surface Glycocalyx in Mechanosensing and Transduction. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1097:1-27. [PMID: 30315537 DOI: 10.1007/978-3-319-96445-4_1] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The endothelial cells (ECs) forming the inner wall of every blood vessel are constantly exposed to the mechanical forces generated by blood flow. The EC responses to these hemodynamic forces play a critical role in the homeostasis of the circulatory system. A variety of mechanosensors and transducers, locating on the EC surface, intra- and trans-EC membrane, and within the EC cytoskeleton, have thus been identified to ensure proper functions of ECs. Among them, the most recent candidate is the endothelial surface glycocalyx (ESG), which is a matrix-like thin layer covering the luminal surface of the EC. It consists of various proteoglycans, glycosaminoglycans, and plasma proteins and is close to other prominent EC mechanosensors and transducers. This chapter summarizes the ESG composition, thickness, and structure observed by different labeling and visualization techniques and in different types of vessels. It also presents the literature in determining the ESG mechanical properties by atomic force microscopy and optical tweezers. The molecular mechanisms by which the ESG plays the role in EC mechanosensing and transduction are described as well as the ESG remodeling by shear stress, the actin cytoskeleton, the membrane rafts, the angiogenic factors, and the sphingosine-1-phosphate.
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Rosa JB, Metzstein MM, Ghabrial AS. An Ichor-dependent apical extracellular matrix regulates seamless tube shape and integrity. PLoS Genet 2018; 14:e1007146. [PMID: 29309404 PMCID: PMC5774827 DOI: 10.1371/journal.pgen.1007146] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 01/19/2018] [Accepted: 12/09/2017] [Indexed: 01/25/2023] Open
Abstract
During sprouting angiogenesis in the vertebrate vascular system, and primary branching in the Drosophila tracheal system, specialized tip cells direct branch outgrowth and network formation. When tip cells lumenize, they form subcellular (seamless) tubes. How these seamless tubes are made, shaped and maintained remains poorly understood. Here we characterize a Drosophila mutant called ichor (ich), and show that ich is essential for the integrity and shape of seamless tubes in tracheal terminal cells. We find that Ich regulates seamless tubulogenesis via its role in promoting the formation of a mature apical extracellular matrix (aECM) lining the lumen of the seamless tubes. We determined that ich encodes a zinc finger protein (CG11966) that acts, as a transcriptional activator required for the expression of multiple aECM factors, including a novel membrane-anchored trypsin protease (CG8213). Thus, the integrity and shape of seamless tubes are regulated by the aECM that lines their lumens.
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Affiliation(s)
- Jeffrey B. Rosa
- Department of Cell & Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Mark M. Metzstein
- Department of Human Genetics, University of Utah, Salt Lake City, Utah, United States of America
| | - Amin S. Ghabrial
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York, United States of America
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18
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Curry FRE. The Molecular Structure of the Endothelial Glycocalyx Layer (EGL) and Surface Layers (ESL) Modulation of Transvascular Exchange. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1097:29-49. [DOI: 10.1007/978-3-319-96445-4_2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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19
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Okada H, Takemura G, Suzuki K, Oda K, Takada C, Hotta Y, Miyazaki N, Tsujimoto A, Muraki I, Ando Y, Zaikokuji R, Matsumoto A, Kitagaki H, Tamaoki Y, Usui T, Doi T, Yoshida T, Yoshida S, Ushikoshi H, Toyoda I, Ogura S. Three-dimensional ultrastructure of capillary endothelial glycocalyx under normal and experimental endotoxemic conditions. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2017; 21:261. [PMID: 29058634 PMCID: PMC5651619 DOI: 10.1186/s13054-017-1841-8] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 09/13/2017] [Indexed: 11/10/2022]
Abstract
BACKGROUND Sugar-protein glycocalyx coats healthy endothelium, but its ultrastructure is not well described. Our aim was to determine the three-dimensional ultrastructure of capillary endothelial glycocalyx in the heart, kidney, and liver, where capillaries are, respectively, continuous, fenestrated, and sinusoidal. METHODS Tissue samples were processed with lanthanum-containing alkaline fixative, which preserves the structure of glycocalyx. RESULTS Scanning and transmission electron microscopy revealed that the endothelial glycocalyx layer in continuous and fenestrated capillaries was substantially thicker than in sinusoids. In the heart, the endothelial glycocalyx presented as moss- or broccoli-like and covered the entire luminal endothelial cell surface. In the kidney, the glycocalyx appeared to nearly occlude the endothelial pores of the fenestrated capillaries and was also present on the surface of the renal podocytes. In sinusoids of the liver, glycocalyx covered not only the luminal side but also the opposite side, facing the space of Disse. In a mouse lipopolysaccharide-induced experimental endotoxemia model, the capillary endothelial glycocalyx was severely disrupted; that is, it appeared to be peeling off the cells and clumping. Serum concentrations of syndecan-1, a marker of glycocalyx damage, were significantly increased 24 h after administration of lipopolysaccharide. CONCLUSIONS In the present study, we visualized the three-dimensional ultrastructure of endothelial glycocalyx in healthy continuous, fenestrated, and sinusoidal capillaries, and we also showed their disruption under experimental endotoxemic conditions. The latter may provide a morphological basis for the microvascular endothelial dysfunction associated with septic injury to organs.
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Affiliation(s)
- Hideshi Okada
- Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan.
| | - Genzou Takemura
- Department of Internal Medicine, Asahi University School of Dentistry, Mizuho, Japan
| | - Kodai Suzuki
- Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
| | - Kazumasa Oda
- Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
| | - Chihiro Takada
- Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
| | - Yasuaki Hotta
- Research Institute for Biotechnology, Asahi University School of Dentistry, Mizuho, Japan
| | - Nagisa Miyazaki
- Department of Internal Medicine, Asahi University School of Dentistry, Mizuho, Japan
| | - Akiko Tsujimoto
- Department of Internal Medicine, Asahi University School of Dentistry, Mizuho, Japan
| | - Isamu Muraki
- Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
| | - Yoshiaki Ando
- Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
| | - Ryogen Zaikokuji
- Laboratory of Molecular Biology, Department of Biofunctional Analysis, Gifu Pharmaceutical University, Gifu, Japan
| | - Atsumu Matsumoto
- Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
| | - Hiroki Kitagaki
- Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
| | - Yuto Tamaoki
- Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
| | - Takahiro Usui
- Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
| | - Tomoaki Doi
- Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
| | - Takahiro Yoshida
- Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
| | - Shozo Yoshida
- Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
| | - Hiroaki Ushikoshi
- Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
| | - Izumi Toyoda
- Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
| | - Shinji Ogura
- Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
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20
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Selmi V, Loriga B, Vitali L, Carlucci M, Di Filippo A, Carta G, Sgambati E, Tofani L, De Gaudio AR, Novelli A, Adembri C. Changes in ceftriaxone pharmacokinetics/pharmacodynamics during the early phase of sepsis: a prospective, experimental study in the rat. J Transl Med 2016; 14:316. [PMID: 27846855 PMCID: PMC5111190 DOI: 10.1186/s12967-016-1072-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Accepted: 11/01/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Sepsis is characterized by the loss of the perm-selectivity properties of the glomerular filtration barrier (GFB) with consequent albuminuria. We examined whether the pharmacokinetics-pharmacodynamics (PK/PD) of ceftriaxone (CTX), an extensively protein-bound 3rd generation cephalosporin, is altered during early sepsis and whether an increase in urinary loss of bound-CTX, due to GFB alteration, can occur in this condition. METHODS A prospective, experimental, randomized study was carried out in adult male Sprague-Dawley rats. Sepsis was induced by cecal ligation and puncture (CLP). Rats were divided into two groups: Sham-operated and CLP. CTX (100 mg i.p., equivalent to 1 g dose in humans) was administered in order to measure plasma and lung CTX concentrations at several time-points: baseline and 1, 2, 4 and 6 h after administration. CTX was measured by High Performance Liquid Chromatography (HPLC). The morphological status of the sialic components of the GFB barrier was assessed by lectin histo-chemistry. Monte Carlo simulation was performed to calculate the probability of target attainment (PTA >90%) for 80 and 100% of Tfree > minimum inhibitory concentration (MIC) for 80 and 100% of dosing interval. MEASUREMENTS AND MAIN RESULTS After CLP, sepsis developed in rats as documented by the growth of polymicrobial flora in the peritoneal fluid (≤1 × 101 CFU in sham rats vs 5 × 104-1 × 105 CFU in CLP rats). CTX plasma concentrations were higher in CLP than in sham rats at 2 and 4 h after administration (difference at 2 h was 47.3, p = 0.012; difference at 4 h was 24.94, p = 0.004), while lung penetration tended to be lower. An increased urinary elimination of protein-bound CTX occurred (553 ± 689 vs 149 ± 128 mg/L, p < 0.05; % of bound/total CTX 22 ± 6 in septic rats vs 11 ± 4 in sham rats, p < 0.01) and it was associated with loss of the GFB sialic components. According to Monte Carlo simulation a PTA > 90% for 100% of the dosing interval was reached neither for sham nor CLP rats using MIC = 1 mg/L, the clinical breakpoint for Enterobacteriacee. CONCLUSIONS Sepsis causes changes in the PK of CTX and an alteration in the sialic components of the GFB, with consequent loss of protein-bound CTX. Among factors that can affect drug pharmacokinetics during the early phases of sepsis, urinary loss of both free and albumin-bound antimicrobials should be considered.
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Affiliation(s)
- Valentina Selmi
- Department of Health Sciences, Section of Anesthesiology and Intensive Care, University of Florence, Azienda Ospedaliero-Universitaria Careggi, Largo Brambilla 3, 50134, Florence, Italy
| | - Beatrice Loriga
- Department of Health Sciences, Section of Anesthesiology and Intensive Care, University of Florence, Azienda Ospedaliero-Universitaria Careggi, Largo Brambilla 3, 50134, Florence, Italy.
| | - Luca Vitali
- Department of Health Sciences, Section of Anesthesiology and Intensive Care, University of Florence, Azienda Ospedaliero-Universitaria Careggi, Largo Brambilla 3, 50134, Florence, Italy
| | - Martina Carlucci
- Department of Health Sciences, Section of Anesthesiology and Intensive Care, University of Florence, Azienda Ospedaliero-Universitaria Careggi, Largo Brambilla 3, 50134, Florence, Italy
| | - Alessandro Di Filippo
- Department of Health Sciences, Section of Anesthesiology and Intensive Care, University of Florence, Azienda Ospedaliero-Universitaria Careggi, Largo Brambilla 3, 50134, Florence, Italy
| | - Giulio Carta
- Department of Health Sciences, Section of Anesthesiology and Intensive Care, University of Florence, Azienda Ospedaliero-Universitaria Careggi, Largo Brambilla 3, 50134, Florence, Italy
| | - Eleonora Sgambati
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090, Pesche, IS, Italy
| | - Lorenzo Tofani
- Department of Neurosciences, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
| | - Angelo Raffaele De Gaudio
- Department of Health Sciences, Section of Anesthesiology and Intensive Care, University of Florence, Azienda Ospedaliero-Universitaria Careggi, Largo Brambilla 3, 50134, Florence, Italy
| | - Andrea Novelli
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Viale Pieraccini 6, 50139, Florence, Italy
| | - Chiara Adembri
- Department of Health Sciences, Section of Anesthesiology and Intensive Care, University of Florence, Azienda Ospedaliero-Universitaria Careggi, Largo Brambilla 3, 50134, Florence, Italy
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Nakanishi M, Grebe R, Bhutto IA, Edwards M, McLeod DS, Lutty GA. Albumen Transport to Bruch's Membrane and RPE by Choriocapillaris Caveolae. Invest Ophthalmol Vis Sci 2016; 57:2213-24. [PMID: 27116549 PMCID: PMC4849865 DOI: 10.1167/iovs.15-17934] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
PURPOSE The choriocapillaris (CC), the capillary network of the choroid, is positioned adjacent to Bruch's membrane (BM) and the RPE. The aim of this study was to clarify the mechanism(s) for transport of serum albumen from CC lumen to RPE. METHODS Alexa647 conjugated to BSA (BSA-A647) or PBS was administrated via the femoral vein to young and aged wild-type (WT; C57BL/6J) mice and Caveolin-1 knockout mice (Cav1(-/-)). Mice were perfused with PBS and killed at 30 minutes, 1 hour, and 4 hours after injection. Eyecups were cryopreserved, and cryosections were analyzed on a Zeiss 710 confocal microscope. Bovine serum albumin conjugated to gold nanoparticles (BSA-GNP) was administrated through the left common carotid artery. Mice were perfused with PBS and killed at 30 minutes after injection. Eyecups were embedded after fixation, and 70-nm-thick sections were analyzed on a Hitachi H7600 transmission electron microscope. RESULTS In eyes of WT young mice, BSA-A647 was transported to the RPE at 30 minutes and diffused to the photoreceptor layer by 1 hour. In contrast, most BSA-A647 was found in the CC in Cav1(-/-) eyes. The majority of BSA-GNP found in the CC of young WT mice was on the luminal side in caveolae at 30 minutes after injection. In aged WT mice, BSA-GNPs were found in defective tight junctions between endothelial cells and appeared trapped at the diaphragm of fenestrations. CONCLUSIONS Normally, CC carefully regulates transport system of BSA from lumen to BM by caveolae-mediated transcytosis; however, endothelium cells of aged control WT mice have leaky tight junctions and lacked regulated BSA transport.
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22
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Hegermann J, Lünsdorf H, Ochs M, Haller H. Visualization of the glomerular endothelial glycocalyx by electron microscopy using cationic colloidal thorium dioxide. Histochem Cell Biol 2015; 145:41-51. [DOI: 10.1007/s00418-015-1378-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/2015] [Indexed: 12/11/2022]
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23
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Lobo DP, Wemyss AM, Smith DJ, Straube A, Betteridge KB, Salmon AHJ, Foster RR, Elhegni HE, Satchell SC, Little HA, Pacheco-Gómez R, Simmons MJ, Hicks MR, Bates DO, Rodger A, Dafforn TR, Arkill KP. Direct detection and measurement of wall shear stress using a filamentous bio-nanoparticle. NANO RESEARCH 2015; 8:3307-3315. [PMID: 27570611 PMCID: PMC4996322 DOI: 10.1007/s12274-015-0831-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 06/04/2015] [Accepted: 06/08/2015] [Indexed: 05/24/2023]
Abstract
The wall shear stress (WSS) that a moving fluid exerts on a surface affects many processes including those relating to vascular function. WSS plays an important role in normal physiology (e.g. angiogenesis) and affects the microvasculature's primary function of molecular transport. Points of fluctuating WSS show abnormalities in a number of diseases; however, there is no established technique for measuring WSS directly in physiological systems. All current methods rely on estimates obtained from measured velocity gradients in bulk flow data. In this work, we report a nanosensor that can directly measure WSS in microfluidic chambers with sub-micron spatial resolution by using a specific type of virus, the bacteriophage M13, which has been fluorescently labeled and anchored to a surface. It is demonstrated that the nanosensor can be calibrated and adapted for biological tissue, revealing WSS in micro-domains of cells that cannot be calculated accurately from bulk flow measurements. This method lends itself to a platform applicable to many applications in biology and microfluidics.
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Affiliation(s)
- Daniela P Lobo
- Department of Chemistry and Warwick Analytical Science Centre, University of Warwick, Coventry CV4 7AL, UK
| | - Alan M Wemyss
- Department of Chemistry and Warwick Analytical Science Centre, University of Warwick, Coventry CV4 7AL, UK; MOAC Doctoral Training Centre, University of Warwick, Coventry CV4 7AL, UK
| | - David J Smith
- Mathematics, University of Birmingham, Edgbaston, Birmingham, West Midlands B15 2TT, UK
| | - Anne Straube
- Centre for Mechanochemical Cell Biology, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Kai B Betteridge
- Physiology and Pharmacology, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Andrew H J Salmon
- Physiology and Pharmacology, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Rebecca R Foster
- Clinical Sciences, Whitson Street, University of Bristol, Bristol BS1 3NY, UK
| | - Hesham E Elhegni
- Clinical Sciences, Whitson Street, University of Bristol, Bristol BS1 3NY, UK
| | - Simon C Satchell
- Clinical Sciences, Whitson Street, University of Bristol, Bristol BS1 3NY, UK
| | - Haydn A Little
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, West Midlands B15 2TT, UK
| | - Raúl Pacheco-Gómez
- Biosciences, University of Birmingham, Edgbaston, Birmingham, West Midlands B15 2TT, UK
| | - Mark J Simmons
- Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, West Midlands B15 2TT, UK
| | - Matthew R Hicks
- Biosciences, University of Birmingham, Edgbaston, Birmingham, West Midlands B15 2TT, UK
| | - David O Bates
- School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham NG2 7UH, UK
| | - Alison Rodger
- Department of Chemistry and Warwick Analytical Science Centre, University of Warwick, Coventry CV4 7AL, UK
| | - Timothy R Dafforn
- Biosciences, University of Birmingham, Edgbaston, Birmingham, West Midlands B15 2TT, UK
| | - Kenton P Arkill
- Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, UK
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Fogarty SW, Patel II, Martin FL, Fullwood NJ. Surface-enhanced Raman spectroscopy of the endothelial cell membrane. PLoS One 2014; 9:e106283. [PMID: 25188340 PMCID: PMC4154719 DOI: 10.1371/journal.pone.0106283] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 08/03/2014] [Indexed: 11/18/2022] Open
Abstract
We applied surface-enhanced Raman spectroscopy (SERS) to cationic gold-labeled endothelial cells to derive SERS-enhanced spectra of the bimolecular makeup of the plasma membrane. A two-step protocol with cationic charged gold nanoparticles followed by silver-intensification to generate silver nanoparticles on the cell surface was employed. This protocol of post-labelling silver-intensification facilitates the collection of SERS-enhanced spectra from the cell membrane without contribution from conjugated antibodies or other molecules. This approach generated a 100-fold SERS-enhancement of the spectral signal. The SERS spectra exhibited many vibrational peaks that can be assigned to components of the cell membrane. We were able to carry out spectral mapping using some of the enhanced wavenumbers. Significantly, the spectral maps suggest the distribution of some membrane components are was not evenly distributed over the cells plasma membrane. These results provide some possible evidence for the existence of lipid rafts in the plasma membrane and show that SERS has great potential for the study and characterization of cell surfaces.
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Affiliation(s)
- Simon W. Fogarty
- Division of Biomedical and Life Sciences, Lancaster University, Lancaster, Lancashire, United Kingdom
- Centre for Biophotonics, Lancaster Environment Centre, Lancaster University, Lancaster, Lancashire, United Kingdom
| | - Imran I. Patel
- Centre for Biophotonics, Lancaster Environment Centre, Lancaster University, Lancaster, Lancashire, United Kingdom
- Cavendish Laboratory, University of Cambridge, Cambridge, Cambridgeshire, United Kingdom
| | - Francis L. Martin
- Centre for Biophotonics, Lancaster Environment Centre, Lancaster University, Lancaster, Lancashire, United Kingdom
| | - Nigel J. Fullwood
- Division of Biomedical and Life Sciences, Lancaster University, Lancaster, Lancashire, United Kingdom
- * E-mail:
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Abstract
Mammals are endowed with a complex set of mechanisms that sense mechanical forces imparted by blood flow to endothelial cells (ECs), smooth muscle cells, and circulating blood cells to elicit biochemical responses through a process referred to as mechanotransduction. These biochemical responses are critical for a host of other responses, including regulation of blood pressure, control of vascular permeability for maintaining adequate perfusion of tissues, and control of leukocyte recruitment during immunosurveillance and inflammation. This review focuses on the role of the endothelial surface proteoglycan/glycoprotein layer-the glycocalyx (GCX)-that lines all blood vessel walls and is an agent in mechanotransduction and the modulation of blood cell interactions with the EC surface. We first discuss the biochemical composition and ultrastructure of the GCX, highlighting recent developments that reveal gaps in our understanding of the relationship between composition and spatial organization. We then consider the roles of the GCX in mechanotransduction and in vascular permeability control and review the prominent interaction of plasma-borne sphingosine-1 phosphate (S1P), which has been shown to regulate both the composition of the GCX and the endothelial junctions. Finally, we consider the association of GCX degradation with inflammation and vascular disease and end with a final section on future research directions.
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Affiliation(s)
- John M Tarbell
- Department of Biomedical Engineering, The City College of the City University of New York, New York, NY 10031
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Goulbourne CN, Gin P, Tatar A, Nobumori C, Hoenger A, Jiang H, Grovenor CRM, Adeyo O, Esko JD, Goldberg IJ, Reue K, Tontonoz P, Bensadoun A, Beigneux AP, Young SG, Fong LG. The GPIHBP1-LPL complex is responsible for the margination of triglyceride-rich lipoproteins in capillaries. Cell Metab 2014; 19:849-60. [PMID: 24726386 PMCID: PMC4143151 DOI: 10.1016/j.cmet.2014.01.017] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 12/06/2013] [Accepted: 01/17/2014] [Indexed: 12/16/2022]
Abstract
Triglyceride-rich lipoproteins (TRLs) undergo lipolysis by lipoprotein lipase (LPL), an enzyme that is transported to the capillary lumen by an endothelial cell protein, GPIHBP1. For LPL-mediated lipolysis to occur, TRLs must bind to the lumen of capillaries. This process is often assumed to involve heparan sulfate proteoglycans (HSPGs), but we suspected that TRL margination might instead require GPIHBP1. Indeed, TRLs marginate along the heart capillaries of wild-type but not Gpihbp1⁻/⁻ mice, as judged by fluorescence microscopy, quantitative assays with infrared-dye-labeled lipoproteins, and EM tomography. Both cell-culture and in vivo studies showed that TRL margination depends on LPL bound to GPIHBP1. Notably, the expression of LPL by endothelial cells in Gpihbp1⁻/⁻ mice did not restore defective TRL margination, implying that the binding of LPL to HSPGs is ineffective in promoting TRL margination. Our studies show that GPIHBP1-bound LPL is the main determinant of TRL margination.
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Affiliation(s)
- Chris N Goulbourne
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Peter Gin
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Angelica Tatar
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Chika Nobumori
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Andreas Hoenger
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Haibo Jiang
- Department of Materials, University of Oxford, Oxford OX13PH, UK
| | | | - Oludotun Adeyo
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Jeffrey D Esko
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Ira J Goldberg
- Department of Medicine, Columbia University, New York, NY 10032, USA
| | - Karen Reue
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Human Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Peter Tontonoz
- Howard Hughes Medical Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - André Bensadoun
- Division of Nutritional Science, Cornell University, Ithaca, NY 14853, USA
| | - Anne P Beigneux
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Stephen G Young
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Human Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Loren G Fong
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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Adamson RH, Clark JF, Radeva M, Kheirolomoom A, Ferrara KW, Curry FE. Albumin modulates S1P delivery from red blood cells in perfused microvessels: mechanism of the protein effect. Am J Physiol Heart Circ Physiol 2014; 306:H1011-7. [PMID: 24531813 DOI: 10.1152/ajpheart.00829.2013] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Removal of plasma proteins from perfusates increases vascular permeability. The common interpretation of the action of albumin is that it forms part of the permeability barrier by electrostatic binding to the endothelial glycocalyx. We tested the alternate hypothesis that removal of perfusate albumin in rat venular microvessels decreased the availability of sphingosine-1-phosphate (S1P), which is normally carried in plasma bound to albumin and lipoproteins and is required to maintain stable baseline endothelial barriers (Am J Physiol Heart Circ Physiol 303: H825-H834, 2012). Red blood cells (RBCs) are a primary source of S1P in the normal circulation. We compared apparent albumin permeability coefficients [solute permeability (Ps)] measured using perfusates containing albumin (10 mg/ml, control) and conditioned by 20-min exposure to rat RBCs with Ps when test perfusates were in RBC-conditioned protein-free Ringer solution. The control perfusate S1P concentration (439 ± 46 nM) was near the normal plasma value at 37 °C and established a stable baseline Ps (0.9 ± 0.4 × 10(-6) cm/s). Ringer solution perfusate contained 52 ± 8 nM S1P and increased Ps more than 10-fold (16.1 ± 3.9 × 10(-6) cm/s). Consistent with albumin-dependent transport of S1P from RBCs, S1P concentrations in RBC-conditioned solutions decreased as albumin concentration, hematocrit, and temperature decreased. Protein-free Ringer solution perfusates that used liposomes instead of RBCs as flow markers failed to maintain normal permeability, reproducing the "albumin effect" in these mammalian microvessels. We conclude that the albumin effect depends on the action of albumin to facilitate the release and transport of S1P from RBCs that normally provide a significant amount of S1P to the endothelium.
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Affiliation(s)
- R H Adamson
- Department of Physiology and Membrane Biology, University of California, Davis, California; and
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28
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Arkill KP, Qvortrup K, Starborg T, Mantell JM, Knupp C, Michel CC, Harper SJ, Salmon AHJ, Squire JM, Bates DO, Neal CR. Resolution of the three dimensional structure of components of the glomerular filtration barrier. BMC Nephrol 2014; 15:24. [PMID: 24484633 PMCID: PMC3922634 DOI: 10.1186/1471-2369-15-24] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 01/21/2014] [Indexed: 11/13/2022] Open
Abstract
Background The human glomerulus is the primary filtration unit of the kidney, and contains the Glomerular Filtration Barrier (GFB). The GFB had been thought to comprise 3 layers – the endothelium, the basement membrane and the podocyte foot processes. However, recent studies have suggested that at least two additional layers contribute to the function of the GFB, the endothelial glycocalyx on the vascular side, and the sub-podocyte space on the urinary side. To investigate the structure of these additional layers is difficult as it requires three-dimensional reconstruction of delicate sub-microscopic (<1 μm) cellular and extracellular elements. Methods Here we have combined three different advanced electron microscopic techniques that cover multiple orders of magnitude of volume sampled, with a novel staining methodology (Lanthanum Dysprosium Glycosaminoglycan adhesion, or LaDy GAGa), to determine the structural basis of these two additional layers. Serial Block Face Scanning Electron Microscopy (SBF-SEM) was used to generate a 3-D image stack with a volume of a 5.3 x 105 μm3 volume of a whole kidney glomerulus (13% of glomerular volume). Secondly, Focused Ion Beam milling Scanning Electron Microscopy (FIB-SEM) was used to image a filtration region (48 μm3 volume). Lastly Transmission Electron Tomography (Tom-TEM) was performed on a 0.3 μm3 volume to identify the fine structure of the glycocalyx. Results Tom-TEM clearly showed 20 nm fibre spacing in the glycocalyx, within a limited field of view. FIB-SEM demonstrated, in a far greater field of view, how the glycocalyx structure related to fenestrations and the filtration slits, though without the resolution of TomTEM. SBF-SEM was able to determine the extent of the sub-podocyte space and glycocalyx coverage, without additional heavy metal staining. Neither SBF- nor FIB-SEM suffered the anisotropic shrinkage under the electron beam that is seen with Tom-TEM. Conclusions These images demonstrate that the three dimensional structure of the GFB can be imaged, and investigated from the whole glomerulus to the fine structure of the glycocalyx using three dimensional electron microscopy techniques. This should allow the identification of structural features regulating physiology, and their disruption in pathological states, aiding the understanding of kidney disease.
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Affiliation(s)
- Kenton P Arkill
- Nanoscale Physics Research Laboratories, School of Physics and Astronomy, University of Birmingham, Birmingham, UK.
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29
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The fetomaternal interface shows vascular hypoglycosylation in the tammar wallaby Macropus eugenii: Comparison with a range of non-mammalian and eutherian placentae. Placenta 2013; 34:879-84. [DOI: 10.1016/j.placenta.2013.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 07/05/2013] [Accepted: 07/09/2013] [Indexed: 11/23/2022]
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30
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Foster RR, Armstrong L, Baker S, Wong DWL, Wylie EC, Ramnath R, Jenkins R, Singh A, Steadman R, Welsh GI, Mathieson PW, Satchell SC. Glycosaminoglycan regulation by VEGFA and VEGFC of the glomerular microvascular endothelial cell glycocalyx in vitro. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 183:604-16. [PMID: 23770346 DOI: 10.1016/j.ajpath.2013.04.019] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 02/18/2013] [Accepted: 04/03/2013] [Indexed: 10/26/2022]
Abstract
Damage to endothelial glycocalyx impairs vascular barrier function and may contribute to progression of chronic vascular disease. An early indicator is microalbuminuria resulting from glomerular filtration barrier damage. We investigated the contributions of hyaluronic acid (HA) and chondroitin sulfate (CS) to glomerular microvascular endothelial cell (GEnC) glycocalyx and examined whether these are modified by vascular endothelial growth factors A and C (VEGFA and VEGFC). HA and CS were imaged on GEnCs and their resynthesis was examined. The effect of HA and CS on transendothelial electrical resistance (TEER) and labeled albumin flux across monolayers was assessed. Effects of VEGFA and VEGFC on production and charge characteristics of glycosaminoglycan (GAG) were examined via metabolic labeling and liquid chromatography. GAG shedding was quantified using Alcian Blue. NDST2 expression was examined using real-time PCR. GEnCs expressed HA and CS in the glycocalyx. CS contributed to the barrier to both ion (TEER) and protein flux across the monolayer; HA had only a limited effect. VEGFC promoted HA synthesis and increased the charge density of synthesized GAGs. In contrast, VEGFA induced shedding of charged GAGs. CS plays a role in restriction of macromolecular flux across GEnC monolayers, and VEGFA and VEGFC differentially regulate synthesis, charge, and shedding of GAGs in GEnCs. These observations have important implications for endothelial barrier regulation in glomerular and other microvascular beds.
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Affiliation(s)
- Rebecca R Foster
- Academic Renal Unit, School of Clinical Sciences, Southmead Hospital, University of Bristol, Bristol, United Kingdom.
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Fu BM, Tarbell JM. Mechano-sensing and transduction by endothelial surface glycocalyx: composition, structure, and function. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2013; 5:381-90. [PMID: 23401243 DOI: 10.1002/wsbm.1211] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The endothelial cells (ECs) lining every blood vessel wall are constantly exposed to the mechanical forces generated by blood flow. The EC responses to these hemodynamic forces play a critical role in the homeostasis of the circulatory system. To ensure proper EC mechano-sensing and transduction, there are a variety of mechano-sensors and transducers that have been identified on the EC surface, intra- and trans-EC membrane and within the EC cytoskeleton. Among them, the most recent candidate is the endothelial surface glycocalyx (ESG), which is a matrix-like thin layer covering the luminal surface of the EC. It consists of various proteoglycans, glycosaminoglycans, and plasma proteins, and is close to other prominent EC mechano-sensors and transducers. The ESG thickness was found to be in the order of 0.1-1 µm by different visualization techniques and in different types of vessels. Detailed analysis on the electron microscopy (EM) images of the microvascular ESG revealed a quasi-periodic substructure with the ESG fiber diameter of 10-12 and 20 nm spacing between adjacent fibers. Atomic force microscopy and optical tweezers were applied to investigate the mechanical properties of the ESG on the cultured EC monolayers and in solutions. Enzymatic degradation of specific ESG glycosaminoglycan components was used to directly elucidate the role of the ESG in EC mechano-sensing and transduction by measuring the shear-induced productions of nitric oxide and prostacyclin, two characteristic responses of the ECs to the flow. The unique location, composition, and structure of the ESG determine its role in EC mechano-sensing and transduction.
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Affiliation(s)
- Bingmei M Fu
- Department of Biomedical Engineering, The City College of the City University of New York, New York, NY, USA.
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32
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Abstract
In this issue of Microcirculation, Wagner, Modla, Hossler and Czmmek [25] describe the use of electron tomography to visualize the three-dimensional arrangement of small endothelial vesicles and caveolae of muscle capillaries. Their images show the well-known clusters of fused vesicles communicating with caveolae at the luminal and abluminal surfaces. The advantages of electron tomography are shown by well resolved images of single cytoplasmic vesicles separate from fused vesicle clusters and also by occasional chains of fused vesicles forming trans-endothelial channels. Twenty five to thirty years ago the existence of both trans-endothelial channels and single unattached vesicles was disputed. Also, since some single vesicles and all of the trans-endothelial channels are labeled with a lanthanide tracer present in the perfusate at the time of fixation, this evidence once again raises the question of whether vesicles have a role in vascular permeability to macromolecules. This brief review describes the origin of the vesicle controversy, some of the more recent evidence for and against the participation of vesicles in macromolecular transport and considers some criticisms of ultra-structural evidence for vesicular transport that still require answers.
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