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Hu NW, Lomel BM, Rice EW, Hossain MMN, Sarntinoranont M, Secomb TW, Murfee WL, Balogh P. Estimation of shear stress heterogeneity along capillary segments in angiogenic rat mesenteric microvascular networks. Microcirculation 2023; 30:e12830. [PMID: 37688531 DOI: 10.1111/micc.12830] [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] [Received: 06/12/2023] [Revised: 08/22/2023] [Accepted: 08/28/2023] [Indexed: 09/11/2023]
Abstract
OBJECTIVE Fluid shear stress is thought to be a regulator of endothelial cell behavior during angiogenesis. The link, however, requires an understanding of stress values at the capillary level in angiogenic microvascular networks. Critical questions remain. What are the stresses? Do capillaries experience similar stress magnitudes? Can variations explain vessel-specific behavior? The objective of this study was to estimate segment-specific shear stresses in angiogenic networks. METHODS Images of angiogenic networks characterized by increased vascular density were obtained from rat mesenteric tissues stimulated by compound 48/80-induced mast cell degranulation. Vessels were identified by perfusion of a 40 kDa fixable dextran prior to harvesting and immunolabeling for PECAM. Using a network flow-based segment model with physiologically relevant parameters, stresses were computed per vessel for regions across multiple networks. RESULTS Stresses ranged from 0.003 to 2328.1 dyne/cm2 and varied dramatically at the capillary level. For all regions, the maximum segmental shear stresses were for capillary segments. Stresses along proximal capillaries branching from arteriole inlets were increased compared to stresses along capillaries in more distal regions. CONCLUSIONS The results highlight the variability of shear stresses along angiogenic capillaries and motivate new discussions on how endothelial cells may respond in vivo to segment-specific microenvironment during angiogenesis.
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Affiliation(s)
- Nien-Wen Hu
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Florida, Gainesville, USA
| | - Banks M Lomel
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Florida, Gainesville, USA
| | - Elijah W Rice
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Florida, Gainesville, USA
| | - Mir Md Nasim Hossain
- Department of Mechanical and Industrial Engineering, New Jersey Institute of Technology, New Jersey, Newark, USA
| | - Malisa Sarntinoranont
- Department of Mechanical and Aerospace Engineering, University of Florida, Florida, Gainesville, USA
| | - Timothy W Secomb
- Department of Physiology, University of Arizona, Arizona, Tucson, USA
| | - Walter L Murfee
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Florida, Gainesville, USA
| | - Peter Balogh
- Department of Mechanical and Industrial Engineering, New Jersey Institute of Technology, New Jersey, Newark, USA
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Hossain MMN, Hu NW, Abdelhamid M, Singh S, Murfee WL, Balogh P. Angiogenic Microvascular Wall Shear Stress Patterns Revealed Through Three-dimensional Red Blood Cell Resolved Modeling. FUNCTION 2023; 4:zqad046. [PMID: 37753184 PMCID: PMC10519277 DOI: 10.1093/function/zqad046] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 08/18/2023] [Accepted: 08/21/2023] [Indexed: 09/28/2023] Open
Abstract
The wall shear stress (WSS) exerted by blood flowing through microvascular capillaries is an established driver of new blood vessel growth, or angiogenesis. Such adaptations are central to many physiological processes in both health and disease, yet three-dimensional (3D) WSS characteristics in real angiogenic microvascular networks are largely unknown. This marks a major knowledge gap because angiogenesis, naturally, is a 3D process. To advance current understanding, we model 3D red blood cells (RBCs) flowing through rat angiogenic microvascular networks using state-of-the-art simulation. The high-resolution fluid dynamics reveal 3D WSS patterns occurring at sub-endothelial cell (EC) scales that derive from distinct angiogenic morphologies, including microvascular loops and vessel tortuosity. We identify the existence of WSS hot and cold spots caused by angiogenic surface shapes and RBCs, and notably enhancement of low WSS regions by RBCs. Spatiotemporal characteristics further reveal how fluctuations follow timescales of RBC "footprints." Altogether, this work provides a new conceptual framework for understanding how shear stress might regulate EC dynamics in vivo.
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Affiliation(s)
- Mir Md Nasim Hossain
- Mechanical and Industrial Engineering, New Jersey Institute of Technology, Newark, NJ 07114, USA
| | - Nien-Wen Hu
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA
| | - Maram Abdelhamid
- Mechanical and Industrial Engineering, New Jersey Institute of Technology, Newark, NJ 07114, USA
| | - Simerpreet Singh
- Mechanical and Industrial Engineering, New Jersey Institute of Technology, Newark, NJ 07114, USA
| | - Walter L Murfee
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA
| | - Peter Balogh
- Mechanical and Industrial Engineering, New Jersey Institute of Technology, Newark, NJ 07114, USA
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3
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Hoyle H, Stenger C, Przyborski S. Design considerations of benchtop fluid flow bioreactors for bio-engineered tissue equivalents in vitro. BIOMATERIALS AND BIOSYSTEMS 2022; 8:100063. [PMID: 36824373 PMCID: PMC9934498 DOI: 10.1016/j.bbiosy.2022.100063] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 07/08/2022] [Accepted: 08/30/2022] [Indexed: 10/14/2022] Open
Abstract
One of the major aims of bio-engineering tissue equivalents in vitro is to create physiologically relevant culture conditions to accurately recreate the cellular microenvironment. This often includes incorporation of factors such as the extracellular matrix, co-culture of multiple cell types and three-dimensional culture techniques. These advanced techniques can recapitulate some of the properties of tissue in vivo, however fluid flow is a key aspect that is often absent. Fluid flow can be introduced into cell and tissue culture using bioreactors, which are becoming increasingly common as we seek to produce increasingly accurate tissue models. Bespoke technology is continuously being developed to tailor systems for specific applications and to allow compatibility with a range of culture techniques. For effective perfusion of a tissue culture many parameters can be controlled, ranging from impacts of the fluid flow such as increased shear stress and mass transport, to potentially unwanted side effects such as temperature fluctuations. A thorough understanding of these properties and their implications on the culture model can aid with a more accurate interpretation of results. Improved and more complete characterisation of bioreactor properties will also lead to greater accuracy when reporting culture conditions in protocols, aiding experimental reproducibility, and allowing more precise comparison of results between different systems. In this review we provide an analysis of the different factors involved in the development of benchtop flow bioreactors and their potential biological impacts across a range of applications.
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Key Words
- 3D, three-dimensional
- ABS, acrylonitrile butadiene styrene
- ALI, air-liquid interface
- Bioreactors
- CFD, computational fluid dynamics
- Cell culture
- ECM, extracellular matrix
- FDM, fused deposition modelling
- Fluid flow
- PC, polycarbonate
- PET, polyethylene terephthalate
- PLA, polylactic acid
- PTFE, polytetrafluoroethylene
- SLA, stereolithography
- Tissue engineering
- UL, unstirred layer
- UV, ultraviolet light
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Affiliation(s)
- H.W. Hoyle
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK
| | - C.M.L. Stenger
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK
| | - S.A. Przyborski
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK,NETPark Incubator, Reprocell Europe Ltd., Thomas Wright Way, Sedgefield TS21 3FD, UK,Corresponding author at: Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK.
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4
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Russo TA, Banuth AMM, Nader HB, Dreyfuss JL. Altered shear stress on endothelial cells leads to remodeling of extracellular matrix and induction of angiogenesis. PLoS One 2020; 15:e0241040. [PMID: 33211705 PMCID: PMC7676693 DOI: 10.1371/journal.pone.0241040] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 10/08/2020] [Indexed: 12/17/2022] Open
Abstract
Endothelial cells (ECs) are subjected to physical forces such as shear stress (SS) induced by blood flow that leads to significant changes in morphology, physiology and gene expression. The abnormal mechanical forces applied in the cardiovascular system can influence the development of conditions and diseases such as thrombosis, hypertension and atherosclerosis. This study investigated the expression of glycosaminoglycans (GAGs), proteoglycans and extracellular matrix molecules in ECs exposed to normal and altered SS. ECs were exposed to SS of 12 dyn/cm2 (artery physiological condition) and 4 dyn/cm2 (artery pathological condition). Subsequently, ECs were subjected to immunofluorescence, qPCR, GAG biosynthesis analyses and cell-based assays. SS induced changes in ECs morphology. There were other pathological consequences of altered SS, including inhibited adhesion, stimulation of migration and capillary-like tube formation, as well as increases of GAG synthesis. We observed higher expression of syndecan-4, perlecan, decorin, fibronectin and collagen III α1 and growth factors, including VEGF-A and TGFβ-1. ECs exposed to SS displayed extracellular matrix remodeling as well as expression of cell-matrix and cell-cell interaction molecules. This study contributes to the understanding of how vascular biology is affected by mechanical forces and how these molecules can be affected in cardiovascular diseases.
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Affiliation(s)
- T. A. Russo
- Molecular Biology Division, Department of Biochemistry, Carl Peter von Dietrich Laboratory, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - A. M. M. Banuth
- Molecular Biology Division, Department of Biochemistry, Carl Peter von Dietrich Laboratory, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - H. B. Nader
- Molecular Biology Division, Department of Biochemistry, Carl Peter von Dietrich Laboratory, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - J. L. Dreyfuss
- Molecular Biology Division, Department of Biochemistry, Carl Peter von Dietrich Laboratory, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
- * E-mail:
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Yoshino D, Funamoto K, Sato K, Kenry, Sato M, Lim CT. Hydrostatic pressure promotes endothelial tube formation through aquaporin 1 and Ras-ERK signaling. Commun Biol 2020; 3:152. [PMID: 32242084 PMCID: PMC7118103 DOI: 10.1038/s42003-020-0881-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 03/11/2020] [Indexed: 02/07/2023] Open
Abstract
Vascular tubulogenesis is tightly linked with physiological and pathological events in the living body. Endothelial cells (ECs), which are constantly exposed to hemodynamic forces, play a key role in tubulogenesis. Hydrostatic pressure in particular has been shown to elicit biophysical and biochemical responses leading to EC-mediated tubulogenesis. However, the relationship between tubulogenesis and hydrostatic pressure remains to be elucidated. Here, we propose a specific mechanism through which hydrostatic pressure promotes tubulogenesis. We show that pressure exposure transiently activates the Ras/extracellular signal-regulated kinase (ERK) pathway in ECs, inducing endothelial tubulogenic responses. Water efflux through aquaporin 1 and activation of protein kinase C via specific G protein–coupled receptors are essential to the pressure-induced transient activation of the Ras/ERK pathway. Our approach could provide a basis for elucidating the mechanopathology of tubulogenesis-related diseases and the development of mechanotherapies for improving human health. Yoshino et al. investigate the mechanism by which exposure to pressure promotes endothelial cells to form tubes and find that Aquaporin-mediated water efflux activates the Ras-ERK pathway via PKC and GPCR activation. These findings may be relevant to understand how blood pressure affects vascular tubulogenesis.
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Affiliation(s)
- Daisuke Yoshino
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, 980-8578, Japan. .,Mechanobiology Institute, National University of Singapore, #10-01 T-Lab, 5A Engineering Drive 1, Singapore, 117411, Singapore. .,Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan. .,Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan.
| | - Kenichi Funamoto
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, 980-8578, Japan.,Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Kakeru Sato
- Graduate School of Engineering, Tohoku University, 6-6-01 Aramaki-Aoba, Aoba-ku, Sendai, 980-8579, Japan.,Tokyo Gas Co., Ltd., 1-5-20 Kaigan, Minato-ku, Tokyo, 105-8527, Japan
| | - Kenry
- Department of Biomedical Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Masaaki Sato
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, 980-8578, Japan
| | - Chwee Teck Lim
- Mechanobiology Institute, National University of Singapore, #10-01 T-Lab, 5A Engineering Drive 1, Singapore, 117411, Singapore. .,Department of Biomedical Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore. .,Institute for Health Innovation and Technology (iHealthtech), National University of Singapore, #14-01 MD6, 14 Medical Drive, Singapore, 117599, Singapore.
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6
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Cerino G, Gaudiello E, Muraro MG, Eckstein F, Martin I, Scherberich A, Marsano A. Engineering of an angiogenic niche by perfusion culture of adipose-derived stromal vascular fraction cells. Sci Rep 2017; 7:14252. [PMID: 29079730 PMCID: PMC5660248 DOI: 10.1038/s41598-017-13882-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 10/02/2017] [Indexed: 01/01/2023] Open
Abstract
In vitro recapitulation of an organotypic stromal environment, enabling efficient angiogenesis, is crucial to investigate and possibly improve vascularization in regenerative medicine. Our study aims at engineering the complexity of a vascular milieu including multiple cell-types, a stromal extracellular matrix (ECM), and molecular signals. For this purpose, the human adipose stromal vascular fraction (SVF), composed of a heterogeneous mix of pericytes, endothelial/stromal progenitor cells, was cultured under direct perfusion flow on three-dimensional (3D) collagen scaffolds. Perfusion culture of SVF-cells reproducibly promoted in vitro the early formation of a capillary-like network, embedded within an ECM backbone, and the release of numerous pro-angiogenic factors. Compared to static cultures, perfusion-based engineered constructs were more rapidly vascularized and supported a superior survival of delivered cells upon in vivo ectopic implantation. This was likely mediated by pericytes, whose number was significantly higher (4.5-fold) under perfusion and whose targeted depletion resulted in lower efficiency of vascularization, with an increased host foreign body reaction. 3D-perfusion culture of SVF-cells leads to the engineering of a specialized milieu, here defined as an angiogenic niche. This system could serve as a model to investigate multi-cellular interactions in angiogenesis, and as a module supporting increased grafted cell survival in regenerative medicine.
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Affiliation(s)
- Giulia Cerino
- Departments of Biomedicine and Surgery, University of Basel and University Hospital of Basel, 4031, Basel, Switzerland
| | - Emanuele Gaudiello
- Departments of Biomedicine and Surgery, University of Basel and University Hospital of Basel, 4031, Basel, Switzerland
| | - Manuele Giuseppe Muraro
- Departments of Biomedicine and Surgery, University of Basel and University Hospital of Basel, 4031, Basel, Switzerland
| | - Friedrich Eckstein
- Departments of Biomedicine and Surgery, University of Basel and University Hospital of Basel, 4031, Basel, Switzerland
| | - Ivan Martin
- Departments of Biomedicine and Surgery, University of Basel and University Hospital of Basel, 4031, Basel, Switzerland
| | - Arnaud Scherberich
- Departments of Biomedicine and Surgery, University of Basel and University Hospital of Basel, 4031, Basel, Switzerland
| | - Anna Marsano
- Departments of Biomedicine and Surgery, University of Basel and University Hospital of Basel, 4031, Basel, Switzerland.
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7
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Muller A, Clarke R, Ho H. Fast blood-flow simulation for large arterial trees containing thousands of vessels. Comput Methods Biomech Biomed Engin 2016; 20:160-170. [PMID: 27376402 DOI: 10.1080/10255842.2016.1207170] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Blood flow modelling has previously been successfully carried out in arterial trees to study pulse wave propagation using nonlinear or linear flow solvers. However, the number of vessels used in the simulations seldom grows over a few hundred. The aim of this work is to present a computationally efficient solver coupled with highly detailed arterial trees containing thousands of vessels. The core of the solver is based on a modified transmission line method, which exploits the analogy between electrical current in finite-length conductors and blood flow in vessels. The viscoelastic behaviour of the arterial-wall is taken into account using a complex elastic modulus. The flow is solved vessel by vessel in the frequency domain and the calculated output pressure is then used as an input boundary condition for daughter vessels. The computational results yield pulsatile blood pressure and flow rate for every segment in the tree. This solver is coupled with large arterial trees generated from a three-dimensional constrained constructive optimisation algorithm. The tree contains thousands of blood vessels with radii spanning ~1 mm in the root artery to ~30 μm in leaf vessels. The computation takes seconds to complete for a vasculature of 2048 vessels and less than 2 min for a vasculature of 4096 vessels on a desktop computer.
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Affiliation(s)
- Alexandre Muller
- a Bioengineering Institute, University of Auckland , Auckland , New Zealand.,b ENSEEIHT , National Polytechnic Institute of Toulouse , Toulouse , France
| | - Richard Clarke
- c Department of Engineering Science , University of Auckland , Auckland , New Zealand
| | - Harvey Ho
- a Bioengineering Institute, University of Auckland , Auckland , New Zealand
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8
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Stempien-Otero A, Helterline D, Plummer T, Farris S, Prouse A, Polissar N, Stanford D, Mokadam NA. Mechanisms of bone marrow-derived cell therapy in ischemic cardiomyopathy with left ventricular assist device bridge to transplant. J Am Coll Cardiol 2015; 65:1424-34. [PMID: 25857908 DOI: 10.1016/j.jacc.2015.01.042] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 12/22/2014] [Accepted: 01/27/2015] [Indexed: 11/15/2022]
Abstract
BACKGROUND Clinical trials report improvements in function and perfusion with direct injection of bone marrow cells into the hearts of patients with ischemic cardiomyopathy. Preclinical data suggest these cells improve vascular density, which would be expected to decrease fibrosis and inflammation. OBJECTIVES The goal of this study was to test the hypothesis that bone marrow stem cells (CD34+) will improve histological measurements of vascularity, fibrosis, and inflammation in human subjects undergoing left ventricular assist device (LVAD) placement as a bridge to cardiac transplantation. METHODS Subjects with ischemic cardiomyopathy who were scheduled for placement of an LVAD as a bridge to transplantation underwent bone marrow aspiration the day before surgery; the bone marrow was processed into cell fractions (bone marrow mononuclear cells, CD34+, and CD34-). At LVAD implantation, all fractions and a saline control were injected epicardially into predetermined areas and each injection site marked. At the time of transplantation, injected areas were collected. Data were analyzed by paired Student t test comparing the effect of cell fractions injected within each subject. RESULTS Six subjects completed the study. There were no statistically significant differences in complications with the procedure versus control subjects. Histological analysis indicated that myocardium injected with CD34+ cells had decreased density of endothelial cells compared to saline-injected myocardium. There were no significant differences in fibrosis or inflammation between groups; however, density of activated fibroblasts was decreased in both CD34+ and CD34- injected areas. CONCLUSIONS Tissue analysis does not support the hypothesis that bone marrow-derived CD34+ cells promote increased vascular tissue in humans with ischemic cardiomyopathy via direct injection.
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Affiliation(s)
- April Stempien-Otero
- Department of Medicine, University of Washington School of Medicine, Seattle, Washington.
| | - Deri Helterline
- Department of Medicine, University of Washington School of Medicine, Seattle, Washington
| | - Tabitha Plummer
- Department of Medicine, University of Washington School of Medicine, Seattle, Washington
| | - Stephen Farris
- Department of Medicine, University of Washington School of Medicine, Seattle, Washington
| | - Andrew Prouse
- Department of Medicine, University of Washington School of Medicine, Seattle, Washington
| | - Nayak Polissar
- The Mountain-Whisper-Light Statistics, Seattle, Washington
| | - Derek Stanford
- The Mountain-Whisper-Light Statistics, Seattle, Washington
| | - Nahush A Mokadam
- Department of Surgery, University of Washington School of Medicine, Seattle, Washington
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9
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Kumar NG, Clark A, Roztocil E, Caliste X, Gillespie DL, Cullen JP. Fibrinolytic activity of endothelial cells from different venous beds. J Surg Res 2014; 194:297-303. [PMID: 25481530 DOI: 10.1016/j.jss.2014.09.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 09/05/2014] [Accepted: 09/23/2014] [Indexed: 10/24/2022]
Abstract
BACKGROUND Little is known about the molecular biology of endothelial cells from different venous vascular beds. As a result, our treatment of deep vein thrombosis and pulmonary artery embolism remain identical. As an initial step in understanding venous thromboembolic disease in the trauma and surgical patients, this study sought to investigate the balance between coagulation and fibrinolysis in the pulmonary and deep venous vascular beds and how trauma might influence this balance. MATERIALS AND METHODS Confluent human iliac vein endothelial cells (HIVECs) and human pulmonary artery endothelial cells (HPAECs), were cultured in the absence or presence of tumor necrosis factor (TNFα; 10 ng/mL) for 24 h. The expression of mediators of coagulation and fibrinolysis were determined by Western blot analysis, and plasminogen activator activity was determined by a fibrin clot degradation assay. RESULTS After TNFα stimulation, there was decreased expression of endothelial protein C receptor and thrombomodulin in both HIVECs and HPAECs. TNFα stimulation increased urokinase plasminogen activator expression in both HIVECs and HPAECs. There was an increase in the expression of tissue plasminogen activator and plasminogen activator inhibitor-1 in response to TNFα in HPAECs, but not in HIVECs. There was significantly greater clot degradation in the presence of both the conditioned media and cell extracts from HIVECs, when compared with HPAECs. CONCLUSIONS HPAECs and HIVECs react differently in terms of fibrinolytic potential when challenged with a cytokine associated with inflammation. These findings suggest that endothelial cells from distinct venous vascular beds may differentially regulate the fibrinolytic pathway.
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Affiliation(s)
- Neil G Kumar
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York
| | - Amanda Clark
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York
| | - Elisa Roztocil
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York
| | - Xzabia Caliste
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York
| | - David L Gillespie
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York
| | - John P Cullen
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York.
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10
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Ha H, Nam KH, Lee SJ. Hybrid PIV-PTV technique for measuring blood flow in rat mesenteric vessels. Microvasc Res 2012; 84:242-8. [PMID: 22820216 DOI: 10.1016/j.mvr.2012.07.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 07/06/2012] [Accepted: 07/10/2012] [Indexed: 11/30/2022]
Abstract
The micro-particle tracking velocimetry (μ-PTV) technique is used to obtain the velocity fields of blood flow in the microvasculature under in vivo conditions because it can provide the blood velocity distribution in microvessels with high spatial resolution. The in vivo μ-PTV technique usually requires a few to tens of seconds to obtain a whole velocity profile across the vessel diameter because of the limited number density of tracer particles under in vivo conditions. Thus, the μ-PTV technique alone is limited in measuring unsteady blood flows that fluctuate irregularly due to the heart beating and muscle movement in surrounding tissues. In this study, a new hybrid PIV-PTV technique was established by combining PTV and particle image velocimetry (PIV) techniques to resolve the drawbacks of the μ-PTV method in measuring blood flow in microvessels under in vivo conditions. Images of red blood cells (RBCs) and fluorescent particles in rat mesenteric vessels were obtained simultaneously. Temporal variations of the centerline blood velocity were monitored using a fast Fourier transform-based cross-correlation PIV method. The fluorescence particle images were analyzed using the μ-PTV technique to extract the spatial distribution of the velocity vectors. Data from the μ-PTV and PIV methods were combined to obtain a better estimate of the velocity profile in actual blood flow. This technique will be useful in investigating hemodynamics in microcirculation by measuring unsteady irregular blood flows more accurately.
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Affiliation(s)
- Hojin Ha
- Department of Mechanical Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, Republic of Korea
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11
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Stoner L, Sabatier MJ. Use of ultrasound for non-invasive assessment of flow-mediated dilation. J Atheroscler Thromb 2012; 19:407-21. [PMID: 22659525 DOI: 10.5551/jat.11395] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The pathological complications of atherosclerosis, namely heart attacks and strokes, remain the leading cause of mortality in the Western world. Preceding atherosclerosis is endothelial dysfunction. There is therefore interest in the application of non-invasive clinical tools to assess endothelial function. The flow-mediated dilation (FMD) test is the standard tool used to assess endothelial function. Reduced FMD is an early marker of atherosclerosis and has been noted for its capacity to predict future cardiovascular disease events. This review discusses the measurement of endothelial function using ultrasound, with a focus on the FMD technique.
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Affiliation(s)
- Lee Stoner
- School of Sport and Exercise, Massey University, Wellington, New Zealand.
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12
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The importance of velocity acceleration to flow-mediated dilation. Int J Vasc Med 2012; 2012:589213. [PMID: 22315688 PMCID: PMC3270398 DOI: 10.1155/2012/589213] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Accepted: 10/12/2011] [Indexed: 01/22/2023] Open
Abstract
The validity of the flow-mediated dilation test has been questioned due to the lack of normalization to the primary stimulus, shear stress. Shear stress can be calculated using Poiseuille's law. However, little attention has been given to the most appropriate blood velocity parameter(s) for calculating shear stress. The pulsatile nature of blood flow exposes the endothelial cells to two distinct shear stimuli during the cardiac cycle: a large rate of change in shear at the onset of flow (velocity acceleration), followed by a steady component. The parameter typically entered into the Poiseuille's law equation to determine shear stress is time-averaged blood velocity, with no regard for flow pulsatility. This paper will discuss (1) the limitations of using Posieuille's law to estimate shear stress and (2) the importance of the velocity profile-with emphasis on velocity acceleration-to endothelial function and vascular tone.
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13
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Synergistic Regulation of Angiogenic Sprouting by Biochemical Factors and Wall Shear Stress. Cell Mol Bioeng 2011; 4:547-559. [PMID: 22247741 DOI: 10.1007/s12195-011-0208-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The process of sprouting angiogenesis involves activating endothelial cells in a quiescent monolayer of an existing vessel to degrade and migrate into the underlying matrix to form new blood vessels. While the roles of biochemical factors in angiogenic sprouting have been well characterized, the roles of fluid forces have received much less attention. This review summarizes results that support a role for wall shear stress in post-capillary venules as a mechanical factor capable of synergizing with biochemical factors to stimulate pro-angiogenic signaling in endothelial cells and promote sprout formation.
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14
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Kang H, Bayless KJ, Kaunas R. Fluid shear stress modulates endothelial cell invasion into three-dimensional collagen matrices. Am J Physiol Heart Circ Physiol 2008; 295:H2087-97. [PMID: 18805898 DOI: 10.1152/ajpheart.00281.2008] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Endothelial cells are subjected to biochemical and mechanical stimuli, which regulate their angiogenic potential. We determined the synergistic effects of sphingosine-1-phosphate (S1P) and fluid wall shear stress (WSS) on a previously established model of human umbilical vein endothelial cell invasion into three-dimensional collagen matrices. Collagen matrices were incorporated into a parallel-plate flow chamber to apply controlled WSS to the surface of endothelial monolayers over a period of 24 h. Cell invasion required the presence of S1P, with the effects of S1P being enhanced by shear stress to an extent comparable with S1P combined with angiogenic growth factor stimulation. The number of invading cells depended on the magnitude of shear stress, with a maximal induction at a shear stress of approximately 5 dyn/cm2, whereas the invasion distance was proportional to the magnitude of shear stress. The enhancement of invasion by 5.3 dyn/cm2 shear stress coincided with elevated phosphorylation of Akt and matrix metalloproteinase (MMP)-2 activation. Furthermore, invasion induced by the combined application of WSS and S1P was attenuated by inhibitors of MMPs (GM6001) and the phosphatidylinositol 3-kinase/Akt signaling pathway (wortmannin). These results provide evidence that shear stress is a positive modulator of S1P-induced endothelial cell invasion into collagen matrices through enhanced Akt and MMP-2 activation.
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Affiliation(s)
- Hojin Kang
- Department of Biomedical Engineering, Texas A&M University, 3120 TAMU, College Station, TX 77845-3120, USA
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15
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Deban L, Correale C, Vetrano S, Malesci A, Danese S. Multiple pathogenic roles of microvasculature in inflammatory bowel disease: a Jack of all trades. THE AMERICAN JOURNAL OF PATHOLOGY 2008; 172:1457-66. [PMID: 18458096 DOI: 10.2353/ajpath.2008.070593] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The etiology of Crohn's disease and ulcerative colitis, the two major forms of inflammatory bowel disease (IBD), is still largely unknown. However, it is now clear that the abnormalities underlying pathogenesis of intestinal inflammation are not restricted to those mediated by classic immune cells but also involve nonimmune cells. In particular, advances in vascular biology have outlined a central and multifaceted pathogenic role for the microcirculation in the initiation and perpetuation of IBD. The microcirculation and its endothelial lining play a crucial role in mucosal immune homeostasis through tight regulation of the nature and magnitude of leukocyte migration from the intravascular to the interstitial space. Chronically inflamed IBD microvessels display significant alterations in microvascular physiology and function compared with vessels from healthy and uninvolved IBD intestine. The investigation into human IBD has demonstrated how endothelial activation present in chronically inflamed IBD microvessels results in a functional phenotype that also includes leakiness, chemokine and cytokine expression, procoagulant activity, and angiogenesis. This review contemplates the newly uncovered contribution of intestinal microcirculation to pathogenesis and maintenance of chronic intestinal inflammation. In particular, we assess the multiple roles of the microvascular endothelium in innate immunity, leukocyte recruitment, coagulation and perfusion, and immune-driven angiogenesis in IBD.
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Affiliation(s)
- Livija Deban
- Division of Gastroenterology, Istituto Clinico Humanitas-IRCCS in Gastroenterology, Viale Manzoni, Rozzano, Milan, Italy
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16
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Deban L, Correale C, Vetrano S, Malesci A, Danese S. Multiple pathogenic roles of microvasculature in inflammatory bowel disease: a Jack of all trades. THE AMERICAN JOURNAL OF PATHOLOGY 2008. [PMID: 18458096 DOI: 10.2353/ajpath.2008070593] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The etiology of Crohn's disease and ulcerative colitis, the two major forms of inflammatory bowel disease (IBD), is still largely unknown. However, it is now clear that the abnormalities underlying pathogenesis of intestinal inflammation are not restricted to those mediated by classic immune cells but also involve nonimmune cells. In particular, advances in vascular biology have outlined a central and multifaceted pathogenic role for the microcirculation in the initiation and perpetuation of IBD. The microcirculation and its endothelial lining play a crucial role in mucosal immune homeostasis through tight regulation of the nature and magnitude of leukocyte migration from the intravascular to the interstitial space. Chronically inflamed IBD microvessels display significant alterations in microvascular physiology and function compared with vessels from healthy and uninvolved IBD intestine. The investigation into human IBD has demonstrated how endothelial activation present in chronically inflamed IBD microvessels results in a functional phenotype that also includes leakiness, chemokine and cytokine expression, procoagulant activity, and angiogenesis. This review contemplates the newly uncovered contribution of intestinal microcirculation to pathogenesis and maintenance of chronic intestinal inflammation. In particular, we assess the multiple roles of the microvascular endothelium in innate immunity, leukocyte recruitment, coagulation and perfusion, and immune-driven angiogenesis in IBD.
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Affiliation(s)
- Livija Deban
- Division of Gastroenterology, Istituto Clinico Humanitas-IRCCS in Gastroenterology, Viale Manzoni, Rozzano, Milan, Italy
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17
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Morrow D, Cullen JP, Cahill PA, Redmond EM. Ethanol stimulates endothelial cell angiogenic activity via a Notch- and angiopoietin-1-dependent pathway. Cardiovasc Res 2008; 79:313-21. [PMID: 18448572 DOI: 10.1093/cvr/cvn108] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
AIMS Our aims were to determine the effect of alcohol (EtOH) on endothelial angiogenic activity and to delineate the cell signalling mechanisms involved. METHODS AND RESULTS Treatment of human umbilical vein endothelial cells (HUVECs) with EtOH (1-100 mM, 24 h) dose-dependently increased their network formation on Matrigel (an index of angiogenesis) with a maximum response (2.5- to 3-fold increase) at 25 mM. Ethanol also stimulated the proliferation (by cell count and proliferating cell nuclear antigen expression) and migration (by scratch wound assay) of HUVECs. In parallel cultures, EtOH stimulated Notch receptor (1 and 4) and Notch target gene (hrt-1, -2, and -3) mRNA and protein expression and enhanced CBF-1/RBP-Jk promoter activity. EtOH also stimulated, at the mRNA and protein level, the expression of angiopoietin-1 (Ang1) and its Tie2 receptor in these cells. Knockdown of Notch 1 or 4 by siRNA or inhibition of Notch-mediated, CBF-1/RBP-Jk-regulated gene expression by the Epstein-Barr virus-encoded protein RPMS-1 inhibited both ethanol-induced Ang1/Tie2 expression in HUVECs and their network formation on Matrigel. Moreover, knockdown of Ang1 or Tie2 by siRNA inhibited ethanol-induced endothelial network formation. CONCLUSION These data demonstrate that ethanol, at levels consistent with moderate consumption, enhances endothelial angiogenic activity in vitro by stimulating a novel Notch/CBF-1/RBP-JK-Ang1/Tie2-dependent pathway. These actions of ethanol may be relevant to the cardiovascular effects of alcohol consumption purported by epidemiological studies.
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Affiliation(s)
- David Morrow
- Department of Surgery, University of Rochester Medical Center, Box SURG, 601 Elmwood Avenue, Rochester, NY 14642-8410, USA
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18
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Frampton JP, Shuler ML, Shain W, Hynd MR. Biomedical Technologies for in vitro Screening and Controlled Delivery of Neuroactive Compounds. Cent Nerv Syst Agents Med Chem 2008; 8:203-219. [PMID: 19079777 PMCID: PMC2600660 DOI: 10.2174/187152408785699613] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cell culture models can provide information pertaining to the effective dose, toxiciology, and kinetics, for a variety of neuroactive compounds. However, many in vitro models fail to adequately predict how such compounds will perform in a living organism. At the systems level, interactions between organs can dramatically affect the properties of a compound by alteration of its biological activity or by elimination of it from the body. At the tissue level, interaction between cell types can alter the transport properties of a particular compound, or can buffer its effects on target cells by uptake, processing, or changes in chemical signaling between cells. In any given tissue, cells exist in a three-dimensional environment bounded on all sides by other cells and components of the extracellular matrix, providing kinetics that are dramatically different from the kinetics in traditional two-dimensional cell culture systems. Cell culture analogs are currently being developed to better model the complex transport and processing that occur prior to drug uptake in the CNS, and to predict blood-brain barrier permeability. These approaches utilize microfluidics, hydrogel matrices, and a variety of cell types (including lung epithelial cells, hepatocytes, adipocytes, glial cells, and neurons) to more accurately model drug transport and biological activity. Similar strategies are also being used to control both the spatial and temporal release of therapeutic compounds for targeted treatment of CNS disease.
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Affiliation(s)
- John P Frampton
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, NY, USA
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19
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Wang XL, Fu A, Raghavakaimal S, Lee HC. Proteomic analysis of vascular endothelial cells in response to laminar shear stress. Proteomics 2007; 7:588-596. [PMID: 17309104 DOI: 10.1002/pmic.200600568] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Isotope-coded affinity tags (cICAT) coupled with mass spectrometric analysis is one of the leading technologies for quantitative proteomic profiling and protein quantification. We performed proteomic analysis of bovine aortic endothelial cells (BAEC) in response to laminar shear stress using cICAT labeling coupled with LC-MS/MS. Protein expressions in BAEC under 15 dynes/cm2 of shear stress for 10 min, 3 h, and 6 h were compared with matched stationary controls. Analysis of each sample produced 1800-2400 proteins at >or=75% confidence level. We found 142, 213, and 186 candidate proteins that were up- or down-regulated by at least two-fold after 10 min, 3 h, and 6 h of shear stress, respectively. Some of these proteins have known cellular functions and they encompass many signaling pathways. The signaling pathways that respond to shear stress include those of integrins, G-protein-coupled receptors, glutamate receptors, PI3K/AKT, apoptosis, Notch and cAMP-mediated signaling pathways. The validity of the mass spectrometric analysis was also confirmed by Western blot and confocal immunofluorescence microscopy. The present quantitative proteomic analysis suggests novel potential regulatory mechanisms in vascular endothelial cells in response to shear stress. These results provide preliminary footprints for further studies on the signaling mechanisms induced by shear stress.
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Affiliation(s)
- Xiao-Li Wang
- Department of Internal Medicine, Mayo Clinic, Rochester, MN, USA
| | - Alex Fu
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | | | - Hon-Chi Lee
- Department of Internal Medicine, Mayo Clinic, Rochester, MN, USA
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20
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Morrow D, Cullen JP, Cahill PA, Redmond EM. Cyclic strain regulates the Notch/CBF-1 signaling pathway in endothelial cells: role in angiogenic activity. Arterioscler Thromb Vasc Biol 2007; 27:1289-96. [PMID: 17395855 DOI: 10.1161/atvbaha.107.142778] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OBJECTIVE The purpose of this study was to determine the effect of cyclic strain on Notch signaling in endothelial cells. METHODS AND RESULTS Exposure of human endothelial cells (ECs) to cyclic strain (10%) resulted in temporal upregulation of Notch receptors (1 and 4) at the mRNA and protein level. Cyclic strain significantly increased EC network formation on Matrigel (an index of angiogenesis); network AU=775+/-127 versus 3928+/-400 for static and strained ECs, respectively. In addition, Angiopoietin 1 (Ang1), Tie1, and Tie2 expression were increased and knockdown of Ang1/Tie1,2 by siRNAs decreased cyclic strain-induced network formation. Knockdown of Notch 1 and 4 by siRNA, or inhibition of Notch mediated CBF-1/RBP-Jk regulated gene expression by RPMS-1, caused a significant decrease in cyclic strain-induced network formation and in Tie1 and Tie2 mRNA expression. Notch 1 or Notch 4 siRNA, but not RPMS-1, inhibited cyclic strain-induced Ang1. Constitutive overexpression of Notch IC resulted in increased network formation, and Ang1 and Tie2 mRNA expression, under both static and strain conditions. CONCLUSIONS These data suggest that cyclic strain-stimulated EC angiogenesis is mediated in part through a Notch-dependent, Ang1/Tie2 signaling pathway. This pathway may represent a novel therapeutic target for disease states in which hemodynamic force-induced angiogenesis occurs.
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MESH Headings
- Angiopoietin-1/genetics
- Angiopoietin-1/metabolism
- Cells, Cultured
- Endothelial Cells/metabolism
- Humans
- Immunoglobulin J Recombination Signal Sequence-Binding Protein/genetics
- Immunoglobulin J Recombination Signal Sequence-Binding Protein/metabolism
- Neovascularization, Physiologic
- Proto-Oncogene Proteins/metabolism
- Pulsatile Flow
- RNA Interference
- RNA, Messenger/metabolism
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Receptor, Notch1/metabolism
- Receptor, Notch4
- Receptor, TIE-1/genetics
- Receptor, TIE-1/metabolism
- Receptor, TIE-2/genetics
- Receptor, TIE-2/metabolism
- Receptors, Notch/genetics
- Receptors, Notch/metabolism
- Signal Transduction
- Stress, Mechanical
- Time Factors
- Transfection
- Up-Regulation
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Affiliation(s)
- David Morrow
- University of Rochester Medical Center, Department of Surgery, 601 Elmwood Avenue, Rochester, NY 14642-8410, USA
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21
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Fleming I. Epoxyeicosatrienoic acids, cell signaling and angiogenesis. Prostaglandins Other Lipid Mediat 2007; 82:60-7. [PMID: 17164133 DOI: 10.1016/j.prostaglandins.2006.05.003] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2006] [Revised: 05/05/2006] [Accepted: 05/11/2006] [Indexed: 10/24/2022]
Abstract
Epoxyeicosatrienoic acids (EETs) are generated from arachidonic acid by cytochrome P450 (CYP) epoxygenases the expression of which is determined by hemodynamic and pharmacological stimuli as well as by hypoxia. The activation of CYP epoxygenases in endothelial cells is an important step in the vasodilatation that has been attributed to the endothelium-derived hyperpolarizing factor. However, in addition to regulating vascular tone EETs modulate several signaling cascades and affect cell proliferation, cell migration and angiogenesis. These include the epidermal growth factor receptor, tyrosine kinases and phosphatases, mitogen-activated protein kinases, protein kinase A, cyclooxygenase-2 and several transcription factors. To-date however, the importance of EETs in vascular homeostasis has been largely underestimated because of the labile nature of the EET-forming enzymes in cell culture. This also means that the contribution of CYP-derived products in the vast majority of the experimental models based on cell culture systems to address topics related to vascular signaling/homeostasis and angiogenesis has been overlooked.
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Affiliation(s)
- Ingrid Fleming
- Vascular Signalling Group, Institut für Kardiovaskuläre Physiologie, Johann Wolfgang Goethe-Universität, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany.
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22
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Wong CS, Sgarioto M, Owida AA, Yang W, Rosenfeldt FL, Morsi YS. Polyethyleneterephthalate Provides Superior Retention of Endothelial Cells During Shear Stress Compared to Polytetrafluoroethylene and Pericardium. Heart Lung Circ 2006; 15:371-7. [PMID: 17035084 DOI: 10.1016/j.hlc.2006.08.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Revised: 08/03/2006] [Accepted: 08/03/2006] [Indexed: 10/24/2022]
Abstract
BACKGROUND Polyethyleneterephthalate (PET) and polytetrafluoroethylene (PTFE) are polymers successfully used as large diameter arterial grafts for peripheral vascular surgery. However, these prosthetic grafts are rarely used for coronary bypass surgery because of their low patency rates. Endothelialisation of the lumenal surface of these materials may improve their patency. This study aimed to compare the endothelialisation of PET, PTFE and pericardium by examining their seeding efficiency over time and the effect of various shear stresses on retention of endothelial cells. METHODS Ovine endothelial cells at 4x10(5)cells/cm(2) were seeded onto PET, PTFE and pericardium, and cultured for 1-168 hours. Cell coverage was determined via en face immunocytochemistry and cell retention was quantified after being subjected to shear stresses ranging from 0.018 to 0.037N/m(2) for 15, 30 and 60 minutes. RESULTS Endothelial cells adhered to all of the materials one hour post-seeding. PET exhibited better cell retention rate, ranging from 66.9+/-5.6% at 0.018N/m(2) for 15min to 44.7+/-1.9% at 0.037N/m(2) for 60 minutes, when compared to PTFE and pericardium (p<0.0001, three-way ANOVA). CONCLUSION PET shows superior retention of endothelial cells during shear stress compare to PTFE and pericardium.
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Affiliation(s)
- Cynthia S Wong
- Biomechanics and Tissue Engineering Group, IRIS, Swinburne University of Technology, 533-545 Burwood Road, Hawthorn, Vic. 3122, Australia.
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23
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Hatoum OA, Heidemann J, Binion DG. The intestinal microvasculature as a therapeutic target in inflammatory bowel disease. Ann N Y Acad Sci 2006; 1072:78-97. [PMID: 17057192 DOI: 10.1196/annals.1326.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Chronic inflammation is a complex biologic process which involves immune as well as non-immune cells including the microvasculature and its endothelial lining. Growing evidence suggests that the microvasculature plays an integral role in the pathophysiology of inflammatory bowel disease (IBD; Crohn's disease and ulcerative colitis). The microvasculature contributes to chronic inflammation through altered leukocyte recruitment, impaired perfusion, and angiogenesis leading to tissue remodeling. These diverse areas of IBD microvascular biology represent therapeutic targets that are currently undergoing investigation.
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Affiliation(s)
- Ossama A Hatoum
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, 9200 W. Wisconsin Avenue, Milwaukee, WI 53226, USA
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24
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Bartha K, Rieger H. Vascular network remodeling via vessel cooption, regression and growth in tumors. J Theor Biol 2006; 241:903-18. [PMID: 16545398 DOI: 10.1016/j.jtbi.2006.01.022] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2005] [Revised: 01/23/2006] [Accepted: 01/23/2006] [Indexed: 11/27/2022]
Abstract
The transformation of the regular vasculature in normal tissue into a highly inhomogeneous tumor specific capillary network is described by a theoretical model incorporating tumor growth, vessel cooption, neo-vascularization, vessel collapse and cell death. Compartmentalization of the tumor into several regions differing in vessel density, diameter and in necrosis is observed for a wide range of parameters in agreement with the vessel morphology found in human melanoma. In accord with data for human melanoma the model predicts that microvascular density (MVD), regarded as an important diagnostic tool in cancer treatment, does not necessarily determine the tempo of tumor progression. Instead it is suggested that the MVD of the original tissue as well as the metabolic demand of the individual tumor cell plays the major role in the initial stages of tumor growth.
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Affiliation(s)
- K Bartha
- Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary
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25
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Abstract
Several studies have shown alterations in vascular anatomy and physiology in inflammatory bowel disease (IBD). These findings, together with the observed upregulation of the mediators of angiogenesis in IBD patients, suggest that angiogenesis possibly contributes to the initiation and perpetuation of IBD. There is considerable evidence of an interrelationship between the mechanisms of angiogenesis and chronic inflammation in IBD. The increased expression of endothelial junction adhesion molecules found in IBD patients indicates the presence of active angiogenesis. Evidence that angiogenesis is involved in IBD was also obtained from animal models of colitis, most notably from studies of angiogenesis inhibition. Serum levels of vascular endothelial growth factor (VEGF) correlate with disease activity in human IBD and fall with the use of steroids, thalidomide, or infliximab. Pharmacological inhibition of angiogenesis, therefore, has the potential to be a therapeutic strategy in IBD. This review outlines the evidence that the rate of angiogenesis is increased in the inflamed intestine in IBD and proposes lines for future research in this field.
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Affiliation(s)
- Ioannis E Koutroubakis
- Department of Gastroenterology, University Hospital Heraklion, Heraklion, Crete, Greece.
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26
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Liao F, Li M, Han D, Cao J, Chen K. Biomechanopharmacology: a new borderline discipline. Trends Pharmacol Sci 2006; 27:287-9. [PMID: 16678914 DOI: 10.1016/j.tips.2006.04.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Revised: 02/17/2006] [Accepted: 04/18/2006] [Indexed: 11/25/2022]
Abstract
Flowing blood is more than a drug transporter in pharmacology; its mechanical impact should also be considered. The in vitro pharmacological dose-response pattern of endothelial cellular functions can be significantly modified by in vivo shear stress. A new borderline discipline, biomechanopharmacology, is forming at the boundary between biomechanics and pharmacology. Biomechanopharmacology will probably consist of both the pharmacological intervention of signals induced by biomechanical factors and the biomechanical influence on pharmacokinetics and pharmacodynamics, in addition to the joint effect of biomechanical and pharmacological factors. Recent investigations show that exercise enhances the shear of pulsatile blood flow to stimulate angiogenesis. The benefits of exercise for gaining joint biomechanical and pharmacological effects should be emphasized.
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Affiliation(s)
- Fulong Liao
- Institute of Chinese Materia Medica, China Academy of Traditional Chinese Medicine, Beijing 100700, China.
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27
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Sekiya S, Shimizu T, Yamato M, Kikuchi A, Okano T. Bioengineered cardiac cell sheet grafts have intrinsic angiogenic potential. Biochem Biophys Res Commun 2006; 341:573-82. [PMID: 16434025 DOI: 10.1016/j.bbrc.2005.12.217] [Citation(s) in RCA: 170] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2005] [Accepted: 12/28/2005] [Indexed: 11/19/2022]
Abstract
Previously, we have demonstrated the long-term survival of myocardial cell sheet constructs in vivo, with microvascular network formation throughout the engineered tissues. The understanding and control of these vascularization processes are a key factor for creating thicker functional tissues. Here, we show that cardiac cell sheets express angiogenesis-related genes and form endothelial cell networks in culture. After non-invasive harvest and stacking of cell sheets using temperature-responsive culture dishes, these endothelial cell networks are maintained and result in neovascularization upon in vivo transplantation. Interestingly, we also discovered that all of the graft vessels are derived from the grafts themselves and these vessels migrate to connect with the host vasculature. Finally, blood vessel formation within the grafts can be controlled by changing the ratio of endothelial cells. In conclusion, myocardial tissue grafts engineered with cell sheet technology have their own inherent potential for the in vivo neovascularization that can be regulated in vitro.
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Affiliation(s)
- Sachiko Sekiya
- Institute of Advanced Biomedical Engineering and Science, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
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28
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Michaelis UR, Fleming I. From endothelium-derived hyperpolarizing factor (EDHF) to angiogenesis: Epoxyeicosatrienoic acids (EETs) and cell signaling. Pharmacol Ther 2005; 111:584-95. [PMID: 16380164 DOI: 10.1016/j.pharmthera.2005.11.003] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2005] [Accepted: 11/23/2005] [Indexed: 12/01/2022]
Abstract
Epoxyeicosatrienoic acids (EETs) are generated from arachidonic acid by cytochrome P450 (CYP) epoxygenases. The expression of CYP epoxygenases in endothelial cells is determined by a number of physical (fluid shear stress and cyclic stretch) and pharmacological stimuli as well as by hypoxia. The activation of CYP epoxygenases in endothelial cells is an important step in the nitric oxide and prostacyclin (PGI2)-independent vasodilatation of several vascular beds and EETs have been identified as endothelium-derived hyperpolarizing factors (EDHFs). However, in addition to regulating vascular tone, EETs modulate several signaling cascades and affect cell proliferation, cell migration, and angiogenesis. Signaling molecules modulated by EETs include tyrosine kinases and phosphatases, mitogen-activated protein kinases, protein kinase A (PKA), cyclooxygenase (COX)-2, and several transcription factors. This review summarizes the role of CYP-derived EETs in cell signaling and focuses particularly on their role as intracellular amplifiers of endothelial cell hyperpolarization as well as in cell proliferation and angiogenesis. The angiogenic properties of CYP epoxygenases and CYP-derived EETs implicate that these enzymes may well be accessible targets for anti-angiogenic as well as angiogenic therapies.
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Affiliation(s)
- U Ruth Michaelis
- Vascular Signalling Group, Institut für Kardiovaskuläre Physiologie, Johann Wolfgang Goethe-Universität, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany
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29
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Joung IS, Iwamoto MN, Shiu YT, Quam CT. Cyclic strain modulates tubulogenesis of endothelial cells in a 3D tissue culture model. Microvasc Res 2005; 71:1-11. [PMID: 16368114 DOI: 10.1016/j.mvr.2005.10.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Revised: 10/07/2005] [Accepted: 10/16/2005] [Indexed: 12/23/2022]
Abstract
Angiogenesis is the formation of new blood vessels from preexisting capillaries or venules. It occurs in a mechanically dynamic environment due to blood flow, but the role of hemodynamic forces in angiogenesis remains poorly understood. We have developed a unique in vitro system for the investigation of angiogenesis under cyclic strain. In this system, tubulogenesis of vascular endothelial cells in 3D collagen gels occurs under well-defined cyclic strain, which mimics blood-pressure-induced stretch. Using this system, we demonstrate that cyclic strain results in alignment of endothelial-cord-like structures perpendicular to the principal axis of stretch. Such preferential orientation was the most evident in deep and long cord-like structures. This in vitro system, along with the novel findings of strain-modulated endothelial tube morphology, enables the formation of an experimental basis for understanding the role of cyclic strain in the regulation of angiogenesis.
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Affiliation(s)
- In Suk Joung
- Department of Bioengineering, University of Utah, 20 South 2030 East, BPR Room 506, Salt Lake City, 84112, USA
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30
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Hatoum OA, Binion DG, Gutterman DD. Paradox of simultaneous intestinal ischaemia and hyperaemia in inflammatory bowel disease. Eur J Clin Invest 2005; 35:599-609. [PMID: 16178878 DOI: 10.1111/j.1365-2362.2005.01567.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
This review has focused on evidence regarding intestinal perfusion of inflammatory bowel disease (IBD). Basic investigation has defined an altered microvascular anatomy in the affected IBD bowel, which corresponds with diminished mucosal perfusion in the setting of chronic, long-standing inflammation. Diminished perfusion is linked to impaired wound healing, and may contribute to the continued refractory mucosal damage, which characterizes IBD. Alterations in vascular anatomy and physiology in IBD suggests additional possible mechanisms by which micro-vessels may contribute to the initiation and perpetuation of IBD. This begs the following questions: will angiogenesis within the gut lead to sustained inflammation, does the growing vasculature generate factors that transform the surrounding tissue and does angiogenesis generate vascular anastomosis within the gut, with shunting of blood away from the mucosal surface, impairment of metabolism and potentiation of gut damage? Further studies are required to define the mechanisms that underlie the vascular dysfunction and its role in pathophysiology of IBD.
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Affiliation(s)
- O A Hatoum
- Division of Cardiovascular Medicine, Froedtert Memorial Lutheran Hospital, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
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Von Offenberg Sweeney N, Cummins PM, Cotter EJ, Fitzpatrick PA, Birney YA, Redmond EM, Cahill PA. Cyclic strain-mediated regulation of vascular endothelial cell migration and tube formation. Biochem Biophys Res Commun 2005; 329:573-82. [PMID: 15737624 DOI: 10.1016/j.bbrc.2005.02.013] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2005] [Indexed: 11/20/2022]
Abstract
UNLABELLED Hemodynamic forces exerted by blood flow (cyclic strain, shear stress) affect the initiation and progression of angiogenesis; however, the precise signaling mechanism(s) involved are unknown. In this study, we examine the role of cyclic strain in regulating bovine aortic endothelial cell (BAEC) migration and tube formation, indices of angiogenesis. Considering their well-documented mechanosensitivity, functional inter-dependence, and involvement in angiogenesis, we hypothesized roles for matrix metalloproteinases (MMP-2/9), RGD-dependent integrins, and urokinase plasminogen activator (uPA) in this process. BAECs were exposed to equibiaxial cyclic strain (5% strain, 1Hz for 24h) before their migration and tube formation was assessed by transwell migration and collagen gel tube formation assays, respectively. In response to strain, both migration and tube formation were increased by 1.83+/-0.1- and 1.84+/-0.1-fold, respectively. Pertussis toxin, a Gi-protein inhibitor, decreased strain-induced migration by 45.7+/-32% and tube formation by 69.8+/-13%, whilst protein tyrosine kinase (PTK) inhibition with genistein had no effect. siRNA-directed attenuation of endothelial MMP-9 (but not MMP-2) expression/activity decreased strain-induced migration and tube formation by 98.6+/-41% and 40.7+/-31%, respectively. Finally, integrin blockade with cRGD peptide and siRNA-directed attenuation of uPA expression reduced strain-induced tube formation by 85.7+/-15% and 84.7+/-31%, respectively, whilst having no effect on migration. CONCLUSIONS Cyclic strain promotes BAEC migration and tube formation in a Gi-protein-dependent PTK-independent manner. Moreover, we demonstrate for the first time a putative role for MMP-9 in both strain-induced events, whilst RGD-dependent integrins and uPA appear only to be involved in strain-induced tube formation.
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Morrow D, Sweeney C, Birney YA, Cummins PM, Walls D, Redmond EM, Cahill PA. Cyclic Strain Inhibits Notch Receptor Signaling in Vascular Smooth Muscle Cells In Vitro. Circ Res 2005; 96:567-75. [PMID: 15705961 DOI: 10.1161/01.res.0000159182.98874.43] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Notch signaling has been shown recently to regulate vascular cell fate in adult cells. By applying a uniform equibiaxial cyclic strain to vascular smooth muscle cells (SMCs), we investigated the role of strain in modulating Notch-mediated growth of SMCs in vitro. Rat SMCs cultured under conditions of defined equibiaxial cyclic strain (0% to 15% stretch; 60 cycles/min; 0 to 24 hours) exhibited a significant temporal and force-dependent reduction in Notch 3 receptor expression, concomitant with a significant reduction in Epstein Barr virus latency C promoter-binding factor-1/recombination signal-binding protein of the Jkappa immunoglobulin gene-dependent Notch target gene promoter activity and mRNA levels when compared with unstrained controls. The decrease in Notch signaling was Gi-protein- and mitogen-activated protein kinase-dependent. In parallel cultures, cyclic strain inhibited SMC proliferation (cell number and proliferating cell nuclear antigen expression) while significantly promoting SMC apoptosis (annexin V binding, caspase-3 activity and bax/bcl-x(L) ratio). Notch 3 receptor overexpression significantly reversed the strain-induced changes in SMC proliferation and apoptosis to levels comparable to unstrained control cells, whereas Notch inhibition further potentiated the changes in SMC apoptosis and proliferation. These findings suggest that cyclic strain inhibits SMC growth while enhancing SMC apoptosis, in part, through regulation of Notch receptor and downstream target gene expression.
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MESH Headings
- Animals
- Apoptosis/physiology
- Cell Division/physiology
- Cells, Cultured/physiology
- DNA-Binding Proteins/physiology
- Gene Expression Regulation
- Immunoglobulin J Recombination Signal Sequence-Binding Protein
- Muscle, Smooth, Vascular/cytology
- Myocytes, Smooth Muscle/physiology
- Nuclear Proteins/physiology
- Proto-Oncogene Proteins/antagonists & inhibitors
- Proto-Oncogene Proteins/biosynthesis
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins/physiology
- Proto-Oncogene Proteins c-bcl-2/biosynthesis
- Proto-Oncogene Proteins c-bcl-2/genetics
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- RNA, Small Interfering/pharmacology
- Rats
- Receptor, Notch1
- Receptors, Cell Surface/antagonists & inhibitors
- Receptors, Cell Surface/biosynthesis
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/physiology
- Recombinant Fusion Proteins/antagonists & inhibitors
- Recombinant Fusion Proteins/biosynthesis
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/physiology
- Signal Transduction/physiology
- Stress, Mechanical
- Transcription Factors/genetics
- Transcription Factors/physiology
- Transfection
- bcl-2-Associated X Protein
- bcl-X Protein
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Affiliation(s)
- David Morrow
- Vascular Health Research Centre, Faculty of Science and Health, Dublin City University, Dublin, Ireland
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Zheng W, Christensen LP, Tomanek RJ. Stretch induces upregulation of key tyrosine kinase receptors in microvascular endothelial cells. Am J Physiol Heart Circ Physiol 2005; 287:H2739-45. [PMID: 15548727 DOI: 10.1152/ajpheart.00410.2004] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We previously demonstrated that cyclic stretch of cardiac myocytes activates paracrine signaling via vascular endothelial growth factor (VEGF) leading to angiogenesis. The present study tested the hypothesis that cyclic stretch upregulates tyrosine kinase receptors in rat coronary microvascular endothelial cells (RCMEC) and human umbilical vein endothelial cells (HUVEC). VEGF receptor-2 (Flk-1) protein levels increased in HUVEC and RCMEC in a time-dependent manner, but the increase occurred much earlier in RCMEC than in HUVEC. The enhancement of Flk-1 protein level was not inhibited by addition of VEGF neutralizing antibodies, indicating that VEGF is not involved in stretch-induced Flk-1 expression. VEGF receptor-1 (Flt-1) protein and mRNA were not changed by stretch. However, Tie-2 and Tie-1 protein levels increased in RCMEC. Angiopoietin-1 and -2, the ligands for Tie-2, increased in cardiac myocytes subjected to cyclic stretch but were not affected by stretch in endothelial cells (EC). Stretch or incubation of RCMEC with VEGF increased cell proliferation moderately, whereas stretch + VEGF had an additive effect on proliferation. Mechanical stretch induces upregulation of the key tyrosine kinase receptors Flk-1, Tie-2, and Tie-1 in vascular EC, which underlies the increase in sensitivity of EC to growth factors and, therefore, facilitates angiogenesis. These in vitro findings support the concept that stretch of cardiac myocytes and EC plays a key role in coronary angiogenesis.
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MESH Headings
- Angiopoietins/metabolism
- Animals
- Cells, Cultured
- Coronary Circulation/physiology
- Endothelium, Vascular/cytology
- Endothelium, Vascular/physiology
- Gene Expression
- Microcirculation/physiology
- Myocytes, Cardiac/cytology
- Myocytes, Cardiac/metabolism
- Neovascularization, Physiologic/physiology
- Rats
- Rats, Sprague-Dawley
- Receptor, TIE-1/genetics
- Receptor, TIE-1/metabolism
- Receptor, TIE-2/genetics
- Receptor, TIE-2/metabolism
- Up-Regulation
- Vascular Endothelial Growth Factor A/pharmacology
- Vascular Endothelial Growth Factor Receptor-2/genetics
- Vascular Endothelial Growth Factor Receptor-2/metabolism
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Affiliation(s)
- Wei Zheng
- Dept. of Anatomy and Cell Biology, 1-402, Bowen Science Bldg., Univ. of Iowa, Iowa City, IA 52242, USA
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Ueda A, Koga M, Ikeda M, Kudo S, Tanishita K. Effect of shear stress on microvessel network formation of endothelial cells with in vitro three-dimensional model. Am J Physiol Heart Circ Physiol 2004; 287:H994-1002. [PMID: 15130887 DOI: 10.1152/ajpheart.00400.2003] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Shear stress stimulus is expected to enhance angiogenesis, the formation of microvessels. We determined the effect of shear stress stimulus on three-dimensional microvessel formation in vitro. Bovine pulmonary microvascular endothelial cells were seeded onto collagen gels with basic fibroblast growth factor to make a microvessel formation model. We observed this model in detail using phase-contrast microscopy, confocal laser scanning microscopy, and electron microscopy. The results show that cells invaded the collagen gel and reconstructed the tubular structures, containing a clearly defined lumen consisting of multiple cells. The model was placed in a parallel-plate flow chamber. A laminar shear stress of 0.3 Pa was applied to the surfaces of the cells for 48 h. Promotion of microvessel network formation was detectable after approximately 10 h in the flow chamber. After 48 h, the length of networks exposed to shear stress was 6.17 (+/-0.59) times longer than at the initial state, whereas the length of networks not exposed to shear stress was only 3.30 (+/-0.41) times longer. The number of bifurcations and endpoints increased for networks exposed to shear stress, whereas the number of bifurcations alone increased for networks not exposed to shear stress. These results demonstrate that shear stress applied to the surfaces of endothelial cells on collagen gel promotes the growth of microvessel network formation in the gel and expands the network because of repeated bifurcation and elongation.
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Affiliation(s)
- Akinori Ueda
- School of Fundamental Science and Technology, Keio University, Yokohama 223-8522, Japan.
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Cotter EJ, von Offenberg Sweeney N, Coen PM, Birney YA, Glucksman MJ, Cahill PA, Cummins PM. Regulation of Endopeptidases EC3.4.24.15 and EC3.4.24.16 in Vascular Endothelial Cells by Cyclic Strain: Role of Gi Protein Signaling. Arterioscler Thromb Vasc Biol 2004; 24:457-63. [PMID: 14726412 DOI: 10.1161/01.atv.0000117176.71143.a1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Endopeptidase EC3.4.24.15 (EP24.15)- and EC3.4.24.16 (EP24.16)-specific peptide hydrolysis plays an important role in endothelium-mediated vasoregulation. Given the significant influence of hemodynamic forces on vascular homeostasis and pathology, we postulated that these related peptidases may be mechanosensitive. The objective of this study, therefore, was to investigate the putative role of cyclic strain in regulating the expression and enzymatic activity of EP24.15 and EP24.16 in bovine aortic endothelial cells (BAECs). METHODS AND RESULTS BAECs were cultured under conditions of defined cyclic strain (0% to 10% stretch, 60 cycles/min, 0 to 24 hours). Strain significantly increased EP24.15 and EP24.16 soluble activity in a force- and time-dependent manner, with elevations of 2.3+/-0.4- and 1.9+/-0.3-fold for EP24.15 and EP24.16, respectively, after 24 hours at 10% strain. Pharmacological agents and dominant-negative G protein mutants used to selectively disrupt Gi(alpha)- and Gbetagamma-mediated signaling pathways attenuated strain-dependent (24 hours, 5%) increases for both enzymes. Differences in the inhibitory profile for both enzymes were also noted, with EP24.15 displaying greater sensitivity to Gi(alpha2/3) inhibition and EP24.16 exhibiting greater sensitivity to Gi(alpha1/2) and Gbetagamma inhibition. Cyclic strain also increased levels of secreted EP24.15 and EP24.16 activity by 2.6+/-0.02- and 3.6+/-0.2-fold, respectively, in addition to mRNA levels for both enzymes (EP24.15 +42%, EP24.16 +56%). CONCLUSIONS Our findings suggest that cyclic strain putatively regulates both the mRNA expression and enzymatic function of EP24.15 and EP24.16 in BAECs via alternate Gi protein signaling pathways.
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Affiliation(s)
- Eoin J Cotter
- Vascular Health Research Centre, Faculty of Science and Health, Dublin City University, Glasnevin, Dublin, Ireland
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Tzima E, Reader JS, Irani-Tehrani M, Ewalt KL, Schwartz MA, Schimmel P. Biologically active fragment of a human tRNA synthetase inhibits fluid shear stress-activated responses of endothelial cells. Proc Natl Acad Sci U S A 2003; 100:14903-7. [PMID: 14630953 PMCID: PMC299850 DOI: 10.1073/pnas.2436330100] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human tryptophanyl-tRNA synthetase (TrpRS) is active in translation and angiogenesis. In particular, an N-terminally truncated fragment, T2-TrpRS, that is closely related to a natural splice variant is a potent antagonist of vascular endothelial growth factor-induced angiogenesis in several in vivo models. In contrast, full-length native TrpRS is inactive in the same models. However, vascular endothelial growth factor stimulation is only one of many physiological and pathophysiological stimuli to which the vascular endothelium responds. To investigate more broadly the role of T2-TrpRS in vascular homeostasis and pathophysiology, the effect of T2-TrpRS on well characterized endothelial cell (EC) responses to flow-induced fluid shear stress was studied. T2-TrpRS inhibited activation by flow of protein kinase B (Akt), extracellular signal-regulated kinase 1/2, and EC NO synthase and prevented transcription of several shear stress-responsive genes. In addition, T2-TrpRS interfered with the unique ability of ECs to align in the direction of fluid flow. In all of these assays, native TrpRS was inactive, demonstrating that angiogenesis-related activity requires fragment production. These results demonstrate that T2-TrpRS can regulate extracellular signal-activated protein kinase, Akt, and EC NO synthase activation pathways that are associated with angiogenesis, cytoskeletal reorganization, and shear stress-responsive gene expression. Thus, this biological fragment of TrpRS may have a role in the maintenance of vascular homeostasis.
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Affiliation(s)
- E Tzima
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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Qiu WP, Hu Q, Paolocci N, Ziegelstein RC, Kass DA. Differential effects of pulsatile versus steady flow on coronary endothelial membrane potential. Am J Physiol Heart Circ Physiol 2003; 285:H341-6. [PMID: 12793981 DOI: 10.1152/ajpheart.01072.2002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Steady shear stress stimulates transient hyperpolarization coupled to calcium-sensitive potassium (KCa) channels and sustained depolarization linked to chloride-selective channels. Physiological flow is pulsatile not static, and whereas in vivo data suggest phasic shear stress may preferentially activate KCa channels, its differential effects on both currents remain largely unknown. To determine this interaction, coronary endothelial cells were cultured in glass capillary flow tubes, loaded with the voltage-sensitive dye bis-(1,3-dibutylbarbituric acid)trimethine oxonol, and exposed to constant or pulsatile shear stress. The latter was generated by a custom servoperfusion system employing physiological pressure and flow waveforms. Steady shear induced a sustained depolarization inhibited by the Cl- channel blocker DIDS. Even after exposure to steady flow, subsequent transition to pulsatile shear stress further stimulated DIDS-sensitive depolarization. DIDS pretreatment "unmasked" a pulsatile flow-induced hyperpolarization of which magnitude was further enhanced by nifedipine, which augments epoxygenase synthesis. Pulse-shear hyperpolarization was fully blocked by KCa channel inhibition (charybdotoxin + apamin), although these agents had no influence on membrane potential altered by steady flow. Thus KCa-dependent hyperpolarization is preferentially stimulated by pulsatile over steady flow, whereas both can stimulate Cl--dependent depolarization. This supports studies showing greater potency of pulsatile flow for triggering KCa-dependent vasorelaxation.
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Affiliation(s)
- Wei-Ping Qiu
- Department of Medicine, Johns Hopkins Hospital, Baltimore, MD 21287, USA
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