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Szafron JM, Heng EE, Boyd J, Humphrey JD, Marsden AL. Hemodynamics and Wall Mechanics of Vascular Graft Failure. Arterioscler Thromb Vasc Biol 2024; 44:1065-1085. [PMID: 38572650 PMCID: PMC11043008 DOI: 10.1161/atvbaha.123.318239] [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: 09/04/2023] [Accepted: 03/12/2024] [Indexed: 04/05/2024]
Abstract
Blood vessels are subjected to complex biomechanical loads, primarily from pressure-driven blood flow. Abnormal loading associated with vascular grafts, arising from altered hemodynamics or wall mechanics, can cause acute and progressive vascular failure and end-organ dysfunction. Perturbations to mechanobiological stimuli experienced by vascular cells contribute to remodeling of the vascular wall via activation of mechanosensitive signaling pathways and subsequent changes in gene expression and associated turnover of cells and extracellular matrix. In this review, we outline experimental and computational tools used to quantify metrics of biomechanical loading in vascular grafts and highlight those that show potential in predicting graft failure for diverse disease contexts. We include metrics derived from both fluid and solid mechanics that drive feedback loops between mechanobiological processes and changes in the biomechanical state that govern the natural history of vascular grafts. As illustrative examples, we consider application-specific coronary artery bypass grafts, peripheral vascular grafts, and tissue-engineered vascular grafts for congenital heart surgery as each of these involves unique circulatory environments, loading magnitudes, and graft materials.
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Affiliation(s)
- Jason M Szafron
- Departments of Pediatrics (J.M.S., A.L.M.), Stanford University, CA
| | - Elbert E Heng
- Cardiothoracic Surgery (E.E.H., J.B.), Stanford University, CA
| | - Jack Boyd
- Cardiothoracic Surgery (E.E.H., J.B.), Stanford University, CA
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT (J.D.H.)
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Komiyama H, Matsukage T. Debating the State-of-the-Art CTO PCI: Is There Still Room for Discussion? JACC Case Rep 2023; 19:101949. [PMID: 37593591 PMCID: PMC10429723 DOI: 10.1016/j.jaccas.2023.101949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/19/2023]
Affiliation(s)
- Hidenori Komiyama
- Department of Cardiology, Saitama Medical University/Saitama Medical Center, Saitama, Japan
| | - Takashi Matsukage
- Department of Cardiology, Saitama Medical University/Saitama Medical Center, Saitama, Japan
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Goldman J, Liu SQ, Tefft BJ. Anti-Inflammatory and Anti-Thrombogenic Properties of Arterial Elastic Laminae. Bioengineering (Basel) 2023; 10:bioengineering10040424. [PMID: 37106611 PMCID: PMC10135563 DOI: 10.3390/bioengineering10040424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 03/07/2023] [Accepted: 03/16/2023] [Indexed: 03/30/2023] Open
Abstract
Elastic laminae, an elastin-based, layered extracellular matrix structure in the media of arteries, can inhibit leukocyte adhesion and vascular smooth muscle cell proliferation and migration, exhibiting anti-inflammatory and anti-thrombogenic properties. These properties prevent inflammatory and thrombogenic activities in the arterial media, constituting a mechanism for the maintenance of the structural integrity of the arterial wall in vascular disorders. The biological basis for these properties is the elastin-induced activation of inhibitory signaling pathways, involving the inhibitory cell receptor signal regulatory protein α (SIRPα) and Src homology 2 domain-containing protein tyrosine phosphatase 1 (SHP1). The activation of these molecules causes deactivation of cell adhesion- and proliferation-regulatory signaling mechanisms. Given such anti-inflammatory and anti-thrombogenic properties, elastic laminae and elastin-based materials have potential for use in vascular reconstruction.
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Sandner SE, Donovan TJ, Edelstein S, Puskas JD, Angleitner P, Krasopoulos G, Channon K, Gehrig T, Rajakaruna C, Ladyshenskij L, De Silva R, Bonaros N, Bolotin G, Jacobs S, Thielmann M, Choi YH, Ohri S, Lipey A, Friedrich I, Taggart DP. Effects of the harvesting technique and external stenting on progression of vein graft disease 2 years after coronary artery bypass. Eur J Cardiothorac Surg 2022; 62:ezac045. [PMID: 35312782 DOI: 10.1093/ejcts/ezac045] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 01/16/2022] [Accepted: 01/25/2022] [Indexed: 01/07/2023] Open
Abstract
OBJECTIVES In a post hoc analysis of the VEST III trial, we investigated the effect of the harvesting technique on saphenous vein graft (SVG) patency and disease progression after coronary artery bypass grafting. METHODS Angiographic outcomes were assessed in 183 patients undergoing open (126 patients, 252 SVG) or endoscopic harvesting (57 patients, 114 SVG). Overall SVG patency was assessed by computed tomography angiography at 6 months and by coronary angiography at 2 years. Fitzgibbon patency (FP I, II and III) and intimal hyperplasia (IH) in a patient subset were assessed by coronary angiography and intravascular ultrasound, respectively, at 2 years. RESULTS Baseline characteristics were similar between patients who underwent open and those who underwent endoscopic harvesting. Open compared with endoscopic harvesting was associated with higher overall SVG patency rates at 6 months (92.9% vs 80.4%, P = 0.04) and 2 years (90.8% vs 73.9%, P = 0.01), improved FP I, II and III rates (65.2% vs 49.2%; 25.3% vs 45.9%, and 9.5% vs 4.9%, respectively; odds ratio 2.81, P = 0.09) and reduced IH area (-31.8%; P = 0.04) and thickness (-28.9%; P = 0.04). External stenting was associated with improved FP I, II and III rates (odds ratio 2.84, P = 0.01), reduced IH area (-19.5%; P < 0.001) and thickness (-25.0%; P < 0.001) in the open-harvest group and reduced IH area (-12.7%; P = 0.01) and thickness (-9.5%; P = 0.21) in the endoscopic-harvest group. CONCLUSIONS A post-hoc analysis of the VEST III trial showed that open harvesting is associated with improved overall SVG patency and reduced IH. External stenting reduces SVG disease progression, particularly with open harvesting.
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Affiliation(s)
- Sigrid E Sandner
- Department of Cardiac Surgery, Medical University of Vienna, Austria
| | | | | | - John D Puskas
- Department of Cardiovascular Surgery, Mount Sinai Morningside, New York, USA
| | | | - George Krasopoulos
- Department of Cardiac Surgery, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Keith Channon
- Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Thomas Gehrig
- Herzzentrum Trier, Krankenhaus der Barmherzigen Bruder, Trier, Germany
| | - Cha Rajakaruna
- Department of Cardiothoracic Surgery, University Hospitals Bristol, UK
| | - Leonid Ladyshenskij
- Department of Cardiothoracic Surgery, Immanuel Klinikum Bernau, Herzzentrum Brandenburg, Germany
| | - Ravi De Silva
- Department of Cardiothoracic Surgery, Papworth Hospital, Cambridge, UK
| | - Nikolaos Bonaros
- Department of Cardiac Surgery, Medical University of Innsbruck, Austria
| | - Gil Bolotin
- Department of Cardiothoracic Surgery, Rambam Medical Center, Israel
| | - Stephan Jacobs
- Department of Cardiothoracic Surgery, German Heart Centre Berlin, Germany
| | - Matthias Thielmann
- Department of Cardiothoracic Surgery, West-German Heart and Vascular Center Essen, University Hospital Essen, Germany
| | - Yeong-Hoon Choi
- Kerkhoff-Klinik Bad Nauheim, Campus Kerkhoff, Justus-Liebig-University Gießen, Bad Nauheim, Germany
| | - Sunil Ohri
- Department of Cardiothoracic Surgery, University Hospital Southampton, UK
| | - Alexander Lipey
- Department of Cardiothoracic Surgery, Sheba Medical Center, Israel
| | - Ivar Friedrich
- Herzzentrum Trier, Krankenhaus der Barmherzigen Bruder, Trier, Germany
| | - David P Taggart
- Department of Cardiac Surgery, University of Oxford, John Radcliffe Hospital, Oxford, UK
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Lima ML, Silva HSM, Lougon LN, Barros FS, Gomes WJ. Remodeling of ipsilateral ulnar artery after radial artery harvesting for coronary artery bypass graft. Can J Physiol Pharmacol 2021; 99:231-236. [PMID: 33590782 DOI: 10.1139/cjpp-2020-0432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
There are controversies in the literature on the blood supply to the forearm after surgical removal of the radial artery in coronary artery bypass grafting (CABG). The objective was to investigate the arterial remodeling of the ulnar artery after the removal of the radial artery in myocardial revascularization by means of ultrasound examination with color Doppler in the pre- and post-operative periods. This paper describes an observational prospective study of the remodeling of the left brachial and ulnar arteries (donor arm) in 103 right-handed non-consecutive adult patients undergoing CABG with removal of the ipsilateral radial artery using the color Doppler ultrasound examination. In the ulnar artery, a significant increase (P < 0.05) was seen in the following measurements: lumen diameter by 13%, lumen area by 26%, peak systolic flow by 40%, and average flow by 46%. Intima-media thickness measured in the ulnar artery did not show a statistically significant difference (P = 0.22), except in diabetic patients (P = 0.007). We conclude that the ulnar artery undergoes positive physiological remodeling, adapting to the new requirements of chronic increase in flow after the ipsilateral removal of the radial artery to serve as a graft in CABG. There was no evidence of increased intima-media thickness, except in diabetic patients.
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Affiliation(s)
- Melchior L Lima
- Cardiovascular Surgery Center, Meridional Hospital, R. Meridional, 200 - Alto Lage, Cariacica, Espírito Santo, 29151-920, Brazil
| | - Héber S M Silva
- Cardiovascular Surgery Center, Meridional Hospital, R. Meridional, 200 - Alto Lage, Cariacica, Espírito Santo, 29151-920, Brazil
| | - Lourival N Lougon
- Cardiovascular Surgery Center, Meridional Hospital, R. Meridional, 200 - Alto Lage, Cariacica, Espírito Santo, 29151-920, Brazil
| | - Fanilda S Barros
- Cardiovascular Surgery Center, Meridional Hospital, R. Meridional, 200 - Alto Lage, Cariacica, Espírito Santo, 29151-920, Brazil
| | - Walter J Gomes
- Discipline of Cardiovascular Surgery, Escola Paulista de Medicina, Federal University of São Paulo, São Paulo, SP, Brazil
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Affiliation(s)
- G. Steinthorsson
- Department of Vascular Surgery, Yale University School of Medicine, USA
| | - B. Sumpio
- Department of Vascular Surgery, Yale University School of Medicine, USA
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Song K, Qing Y, Guo Q, Peden EK, Chen C, Mitch WE, Truong L, Cheng J. PDGFRA in vascular adventitial MSCs promotes neointima formation in arteriovenous fistula in chronic kidney disease. JCI Insight 2020; 5:137298. [PMID: 33001865 PMCID: PMC7710276 DOI: 10.1172/jci.insight.137298] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 09/24/2020] [Indexed: 12/16/2022] Open
Abstract
Chronic kidney disease (CKD) induces the failure of arteriovenous fistulas (AVFs) and promotes the differentiation of vascular adventitial GLI1-positive mesenchymal stem cells (GMCs). However, the roles of GMCs in forming neointima in AVFs remain unknown. GMCs isolated from CKD mice showed increased potential capacity of differentiation into myofibroblast-like cells. Increased activation of expression of PDGFRA and hedgehog (HH) signaling were detected in adventitial cells of AVFs from patients with end-stage kidney disease and CKD mice. PDGFRA was translocated and accumulated in early endosome when sonic hedgehog was overexpressed. In endosome, PDGFRA-mediated activation of TGFB1/SMAD signaling promoted the differentiation of GMCs into myofibroblasts, extracellular matrix deposition, and vascular fibrosis. These responses resulted in neointima formation and AVF failure. KO of Pdgfra or inhibition of HH signaling in GMCs suppressed the differentiation of GMCs into myofibroblasts. In vivo, specific KO of Pdgfra inhibited GMC activation and vascular fibrosis, resulting in suppression of neointima formation and improvement of AVF patency despite CKD. Our findings could yield strategies for maintaining AVF functions.
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Affiliation(s)
- Ke Song
- Department of Stomatology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Selzman Institute for Kidney Health, Section of Nephrology, Department of Medicine, Baylor College of Medicine, Houston, Texas, USA
| | - Ying Qing
- Selzman Institute for Kidney Health, Section of Nephrology, Department of Medicine, Baylor College of Medicine, Houston, Texas, USA
| | - Qunying Guo
- Selzman Institute for Kidney Health, Section of Nephrology, Department of Medicine, Baylor College of Medicine, Houston, Texas, USA
| | - Eric K Peden
- Department of Vascular Surgery, DeBakey Heart and Vascular Institute, Houston Methodist Hospital, Houston, Texas, USA
| | - Changyi Chen
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas, USA
| | - William E Mitch
- Selzman Institute for Kidney Health, Section of Nephrology, Department of Medicine, Baylor College of Medicine, Houston, Texas, USA
| | - Luan Truong
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA
| | - Jizhong Cheng
- Selzman Institute for Kidney Health, Section of Nephrology, Department of Medicine, Baylor College of Medicine, Houston, Texas, USA
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Cai C, Kilari S, Zhao C, Simeon ML, Misra A, Li Y, van Wijnen AJ, Mukhopadhyay D, Misra S. Therapeutic Effect of Adipose Derived Mesenchymal Stem Cell Transplantation in Reducing Restenosis in a Murine Angioplasty Model. J Am Soc Nephrol 2020; 31:1781-1795. [PMID: 32587073 DOI: 10.1681/asn.2019101042] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Accepted: 04/27/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Percutaneous transluminal angioplasty (PTA) is the first line of treatment for stenosis in the arteriovenous fistula (AVF) created to provide access for hemodialysis, but resenosis still occurs. Transplants of adipose-derived mesenchymal stem cells (AMSCs) labeled with green fluorescent protein (GFP) to the adventitia could reduce pro-inflammatory gene expression, possibly restoring patency in a murine model of PTA for venous stenosis. METHODS Partial nephrectomy of male C57BL/6J mice induced CKD. Placement of the AVF was 28 days later and, 14 days after that, PTA of the stenotic outflow vein was performed with delivery of either vehicle control or AMSCs (5×105) to the adventitia of the vein. Mice were euthanized 3 days later and gene expression for interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha TNF-α) analyzed, and histopathologic analysis performed on day 14 and 28. GFP (+) AMSCs were tracked after transplantation for up to 28 days and Doppler ultrasound performed weekly after AVF creation. RESULTS Gene and protein expression of IL-1β and TNF-α, fibrosis, proliferation, apoptosis and smooth muscle actin decreased, and the proportions of macrophage types (M2/M1) shifted in a manner consistent with less inflammation in AMSC-transplanted vessels compared to controls. After PTA, AMSC-treated vessels had significantly higher wall shear stress, average peak, and mean velocity, with increased lumen vessel area and decreased neointima/media area ratio compared to the control group. At 28 days after delivery, GFP (+) AMSC were present in the adventitia of the outflow vein. CONCLUSIONS AMSC-treated vessels had improved vascular remodeling with decreased proinflammatory gene expression, inflammation, and fibrotic staining compared to untreated vessels.
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Affiliation(s)
- Chuanqi Cai
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Vascular and Interventional Radiology Translational Laboratory, Department of Radiology, Mayo Clinic, Rochester, Minnesota
| | - Sreenivasulu Kilari
- Vascular and Interventional Radiology Translational Laboratory, Department of Radiology, Mayo Clinic, Rochester, Minnesota
| | - Chenglei Zhao
- Vascular and Interventional Radiology Translational Laboratory, Department of Radiology, Mayo Clinic, Rochester, Minnesota.,Department of Vascular Surgery, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Michael L Simeon
- Vascular and Interventional Radiology Translational Laboratory, Department of Radiology, Mayo Clinic, Rochester, Minnesota
| | - Avanish Misra
- Vascular and Interventional Radiology Translational Laboratory, Department of Radiology, Mayo Clinic, Rochester, Minnesota
| | - Yiqing Li
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Andre J van Wijnen
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota.,Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota
| | | | - Sanjay Misra
- Vascular and Interventional Radiology Translational Laboratory, Department of Radiology, Mayo Clinic, Rochester, Minnesota .,Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota.,Department of Radiology, Vascular and Interventional Radiology, Mayo Clinic, Rochester, Minnesota
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Bai H, Wang Z, Li M, Sun P, Wei S, Wang Z, Xing Y, Dardik A. Adult Human Vein Grafts Retain Plasticity of Vessel Identity. Ann Vasc Surg 2020; 68:468-475. [PMID: 32422286 DOI: 10.1016/j.avsg.2020.04.046] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 03/14/2020] [Accepted: 04/18/2020] [Indexed: 01/10/2023]
Abstract
BACKGROUND The spiral saphenous vein graft is an excellent choice for venous reconstruction after periphery vein injury, but only few cases have been reported. We implanted a segment of a single saphenous vein into both the popliteal vein as a venous vein graft and into the popliteal artery as an arterial vein graft at the same time in a trauma patient; we then had an extraordinary opportunity to harvest and examine both patent venous and arterial vein grafts at 2 weeks after implantation. METHODS A spiral saphenous vein graft was made as previously described and implanted into the popliteal vein and artery as interposition grafts; because of the patient's serious injuries, an amputation was performed at day 18 after vascular reconstruction. The grafts were harvested, fixed, and examined using histology and immunohistochemistry. RESULTS Both grafts were patent, and there was a larger neointimal area in the venous graft compared to the arterial graft. There were CD31- and vWF-positive cells on both neointimal endothelia, with subendothelial deposition of α-actin-, CD3-, CD45-, and CD68-positive cells. There were fewer cells in the venous graft neointima compared to the arterial graft neointima; however, there were more inflammatory cells in the neointima of the venous graft. Some of the neointimal cells were PCNA-positive, whereas very few cells were cleaved caspase-3 positive. The venous graft neointimal endothelial cells were Eph-B4 and COUP-TFII positive, while the arterial graft neointimal endothelial cells were dll-4 and Ephrin-B2 positive. CONCLUSIONS The spiral saphenous vein graft remains a reasonable choice for vessel reconstruction, especially in the presence of diameter mismatch. Both the venous and arterial grafts showed similar re-endothelialization and cellular deposition; the venous graft had more neointimal hyperplasia and inflammation. At an early time, endothelial cells showed venous identity in the venous graft, whereas endothelial cells showed arterial identity in the arterial graft. CLINICAL RELEVANCE Veins can be used as venous or arterial vein grafts but venous grafts have more neointimal hyperplasia and inflammation; vein grafts acquire different vessel identity depending on the environment into which they are implanted.
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Affiliation(s)
- Hualong Bai
- Department of Vascular and Endovascular Surgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, People's Republic of China; Department of Physiology, Medical School of Zhengzhou University, Zhengzhou, Henan, People's Republic of China.
| | - Zhiwei Wang
- Department of Vascular and Endovascular Surgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, People's Republic of China
| | - Mingxing Li
- Department of Vascular and Endovascular Surgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, People's Republic of China
| | - Peng Sun
- Department of Vascular and Endovascular Surgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, People's Republic of China
| | - Shunbo Wei
- Department of Vascular and Endovascular Surgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, People's Republic of China
| | - Zhiju Wang
- Key Vascular Physiology and Applied Research Laboratory, Zhengzhou, Henan, People's Republic of China; Department of Physiology, Medical School of Zhengzhou University, Zhengzhou, Henan, People's Republic of China
| | - Ying Xing
- Key Vascular Physiology and Applied Research Laboratory, Zhengzhou, Henan, People's Republic of China; Department of Physiology, Medical School of Zhengzhou University, Zhengzhou, Henan, People's Republic of China
| | - Alan Dardik
- The Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT; Department of Surgery and Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT.
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In Vivo Stability of Polyurethane-Based Electrospun Vascular Grafts in Terms of Chemistry and Mechanics. Polymers (Basel) 2020; 12:polym12040845. [PMID: 32272564 PMCID: PMC7240619 DOI: 10.3390/polym12040845] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 03/25/2020] [Accepted: 03/27/2020] [Indexed: 12/31/2022] Open
Abstract
The biostability of the polyurethanes Tecoflex EG-80A and Pellethane 2363-80A, used as basic polymers of the vascular grafts (VGs) produced by electrospinning, as well as the tensile strength of Tecoflex VGs, are studied. Solutions of Tecoflex or Pellethane with gelatin and bivalirudin in 1,1,1,3,3,3-hexafluoroisopropanol are used for VG production. After 1, 12, and 24 weeks of VG implantation in the infrarenal position of the abdominal aorta of Wistar rats, VGs are explanted, fixed in formalin, freed from outer tissues, dialyzed, and dried. The polyurethanes are extracted from VGs by dispersion/extraction in tetrahydrofuran (THF) and freed from the excess of THF-insoluble biopolymers. The stability of polyurethanes is assessed by IR spectroscopy and gel permeation chromatography. Pellethane has emerged to be stable at all experimental points. Tecoflex loses approximately 10% of its molecular weight (both Mn and Mw) after 3 months and restored its initial value within 6 months of its functioning as a graft. Mechanical testing demonstrates a 30% reduction in the tensile strength after 3 months in VG and a 10% increase after 6 months. The stability and mechanical properties of polyurethane-based VGs demonstrate their utility for the reconstitution of damaged arteries.
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Tarbell J, Mahmoud M, Corti A, Cardoso L, Caro C. The role of oxygen transport in atherosclerosis and vascular disease. J R Soc Interface 2020; 17:20190732. [PMID: 32228404 PMCID: PMC7211472 DOI: 10.1098/rsif.2019.0732] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 03/11/2020] [Indexed: 12/18/2022] Open
Abstract
Atherosclerosis and vascular disease of larger arteries are often associated with hypoxia within the layers of the vascular wall. In this review, we begin with a brief overview of the molecular changes in vascular cells associated with hypoxia and then emphasize the transport mechanisms that bring oxygen to cells within the vascular wall. We focus on fluid mechanical factors that control oxygen transport from lumenal blood flow to the intima and inner media layers of the artery, and solid mechanical factors that influence oxygen transport to the adventitia and outer media via the wall's microvascular system-the vasa vasorum (VV). Many cardiovascular risk factors are associated with VV compression that reduces VV perfusion and oxygenation. Dysfunctional VV neovascularization in response to hypoxia contributes to plaque inflammation and growth. Disturbed blood flow in vascular bifurcations and curvatures leads to reduced oxygen transport from blood to the inner layers of the wall and contributes to the development of atherosclerotic plaques in these regions. Recent studies have shown that hypoxia-inducible factor-1α (HIF-1α), a critical transcription factor associated with hypoxia, is also activated in disturbed flow by a mechanism that is independent of hypoxia. A final section of the review emphasizes hypoxia in vascular stenting that is used to enlarge vessels occluded by plaques. Stenting can compress the VV leading to hypoxia and associated intimal hyperplasia. To enhance oxygen transport during stenting, new stent designs with helical centrelines have been developed to increase blood phase oxygen transport rates and reduce intimal hyperplasia. Further study of the mechanisms controlling hypoxia in the artery wall may contribute to the development of therapeutic strategies for vascular diseases.
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Affiliation(s)
- John Tarbell
- Biomedical Engineering Department, The City College of New York, New York, NY, USA
| | - Marwa Mahmoud
- Biomedical Engineering Department, The City College of New York, New York, NY, USA
| | - Andrea Corti
- Biomedical Engineering Department, The City College of New York, New York, NY, USA
| | - Luis Cardoso
- Biomedical Engineering Department, The City College of New York, New York, NY, USA
| | - Colin Caro
- Department of Bioengineering, Imperial College London, London, UK
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Garbey M, Casarin S, Berceli SA. A versatile hybrid agent-based, particle and partial differential equations method to analyze vascular adaptation. Biomech Model Mechanobiol 2018; 18:29-44. [PMID: 30094656 PMCID: PMC6373284 DOI: 10.1007/s10237-018-1065-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 07/26/2018] [Indexed: 11/27/2022]
Abstract
Peripheral arterial occlusive disease is a chronic pathology affecting at least 8–12 million people in the USA, typically treated with a vein graft bypass or through the deployment of a stent in order to restore the physiological circulation. Failure of peripheral endovascular interventions occurs at the intersection of vascular biology, biomechanics, and clinical decision making. It is our hypothesis that the majority of endovascular treatment approaches share the same driving mechanisms and that a deep understanding of the adaptation process is pivotal in order to improve the current outcome of the procedure. The postsurgical adaptation of vein graft bypasses offers the perfect example of how the balance between intimal hyperplasia and wall remodeling determines the failure or the success of the intervention. Accordingly, this work presents a versatile computational model able to capture the feedback loop that describes the interaction between events at cellular/tissue level and mechano-environmental conditions. The work here presented is a generalization and an improvement of a previous work by our group of investigators, where an agent-based model uses a cellular automata principle on a fixed hexagonal grid to reproduce the leading events of the graft’s restenosis. The new hybrid model here presented allows a more realistic simulation both of the biological laws that drive the cellular behavior and of the active role of the membranes that separate the various layers of the vein. The novel feature is to use an immersed boundary implementation of a highly viscous flow to represent SMC motility and matrix reorganization in response to graft adaptation. Our implementation is modular, and this makes us able to choose the right compromise between closeness to the physiological reality and complexity of the model. The focus of this paper is to offer a new modular implementation that combines the best features of an agent-based model, continuum mechanics, and particle-tracking methods to cope with the multiscale nature of the adaptation phenomena. This hybrid method allows us to quickly test various hypotheses with a particular attention to cellular motility, a process that we demonstrated should be driven by mechanical homeostasis in order to maintain the right balance between cells and extracellular matrix in order to reproduce a distribution similar to histological experimental data from vein grafts.
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Affiliation(s)
- Marc Garbey
- Houston Methodist Research Institute, Houston, TX, USA. .,Department of Surgery, Houston Methodist Hospital, Houston, TX, USA. .,LaSIE, UMR CNRS 7356, University of la Rochelle, La Rochelle, France.
| | - Stefano Casarin
- Houston Methodist Research Institute, Houston, TX, USA.,LaSIE, UMR CNRS 7356, University of la Rochelle, La Rochelle, France
| | - Scott A Berceli
- Department of Surgery, University of Florida, Gainesville, FL, USA.,Malcom Randall VAMC, Gainesville, FL, USA
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13
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Gregory EK, Webb A, Vercammen JM, Kelly ME, Akar B, van Lith R, Bahnson EM, Jiang W, Ameer GA, Kibbe MR. Inhibiting intimal hyperplasia in prosthetic vascular grafts via immobilized all-trans retinoic acid. J Control Release 2018; 274:69-80. [PMID: 29391231 PMCID: PMC5847482 DOI: 10.1016/j.jconrel.2018.01.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 12/15/2017] [Accepted: 01/22/2018] [Indexed: 12/24/2022]
Abstract
Peripheral arterial disease is a leading cause of morbidity and mortality. The most commonly utilized prosthetic material for peripheral bypass grafting is expanded polytetrafluoroethylene (ePTFE) yet it continues to exhibit poor performance from restenosis due to neointimal hyperplasia, especially in femoral distal bypass procedures. Recently, we demonstrated that periadventitial delivery of all-trans retinoic acid (atRA) immobilized throughout porous poly(1,8 octamethylene citrate) (POC) membranes inhibited neointimal formation in a rat arterial injury model. Thus, the objective of this study was to investigate whether atRA immobilized throughout the lumen of ePTFE vascular grafts would inhibit intimal formation following arterial bypass grafting. Utilizing standard ePTFE, two types of atRA-containing ePTFE vascular grafts were fabricated and evaluated: grafts whereby all-trans retinoic acid was directly immobilized on ePTFE (atRA-ePTFE) and grafts where all-trans retinoic acid was immobilized onto ePTFE grafts coated with POC (atRA-POC-ePTFE). All grafts were characterized by SEM, HPLC, and FTIR and physical characteristics were evaluated in vitro. Modification of these grafts, did not significantly alter their physical characteristics or biocompatibility, and resulted in inhibition of intimal formation in a rat aortic bypass model, with atRA-POC-ePTFE inhibiting intimal formation at both the proximal and distal graft sections. In addition, treatment with atRA-POC-ePTFE resulted in increased graft endothelialization and decreased inflammation when compared to the other treatment groups. This work further confirms the biocompatibility and efficacy of locally delivered atRA to inhibit intimal formation in a bypass setting. Thus, atRA-POC-ePTFE grafts have the potential to improve patency rates in small diameter bypass grafts and warrant further investigation.
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Affiliation(s)
- Elaine K Gregory
- Department of Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States; Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, United States
| | - Antonio Webb
- The University of Florida, Gainesville, FL 32611, United States
| | - Janet M Vercammen
- Department of Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States; Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, United States
| | - Megan E Kelly
- Department of Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States; Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, United States
| | - Banu Akar
- Biomedical Engineering Department, McCormick School of Engineering, Northwestern University, Evanston, IL 60201, United States
| | - Robert van Lith
- Biomedical Engineering Department, McCormick School of Engineering, Northwestern University, Evanston, IL 60201, United States; Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, United States
| | - Edward M Bahnson
- Department of Surgery, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States
| | - Wulin Jiang
- Department of Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States; Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, United States
| | - Guillermo A Ameer
- Department of Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States; Biomedical Engineering Department, McCormick School of Engineering, Northwestern University, Evanston, IL 60201, United States; Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, United States
| | - Melina R Kibbe
- Department of Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States; Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, United States; Department of Surgery, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States.
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14
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Baig K, Fields R, Gaca J, Hanish S, Milton L, Koch W, Lawson J. A porcine Model of Intimal-Medial Hyperplasia in Polytetrafluoroethylene Arteriovenous Grafts. J Vasc Access 2018. [DOI: 10.1177/112972980300400306] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Purpose Vascular access polytetrafluoroethylene (PTFE) graft failure is a major cause of morbidity in the hemodialysis population. The most common cause of graft failure is thrombosis secondary to stenosis at the venous outflow tract. Venous outflow stenosis is characterized by intimal-medial hyperplasia. We have developed a porcine arteriovenous (AV) graft model that may be used to investigate this proliferative response and aid in the development of new therapies to prevent intimal-medial hyperplasia and improve graft patency. Methods Left carotid to right external jugular vein PTFE (6 mm) grafts were implanted in the necks of swine. Immediately following anatomosis, flow rates were recorded. In one group of animals (n = 4) the venous outflow tract was harvested after 7 days and morphometric analysis of intimal and medial area was performed. In a second group (n = 8) the graft patency was monitored until 28 days. Results All porcine PTFE fistula grafts were patent at 7 days and 100% patency was maintained until 14 days. After 28 days, 75% of the grafts failed due to thrombosis. The venous outflow tract developed a significant proliferative response. After 7 days the intimal and medial areas were 469 ± 9 μm2 and 875 ± 26 μm2 respectively. At 28 days the intimal and medial areas were 913 ± 55 μm2 and 1437 ± 182 μm2 respectively. Luminal flow rate of the venous outflow tract was reduced significantly (344 ± 11 ml/min at Day 0 to 129 ± 14 ml/min at Day 7, p < 0.05). Conclusions This porcine model rapidly, reliably and robustly reproduces the flow reducing stenosis and intimal-medial hyperplasia at the venous outflow tract of PTFE arteriovenous fistula. It represents a promising tool for investigating the mechanisms of intimal-medial hyperplasia, evaluating therapeutic interventions and new graft materials.
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Affiliation(s)
- K. Baig
- Department of Surgery, Duke University
Medical Center, Durham - USA
| | - R.C. Fields
- Department of Surgery, Duke University
Medical Center, Durham - USA
| | - J. Gaca
- Department of Surgery, Duke University
Medical Center, Durham - USA
| | - S. Hanish
- Department of Surgery, Duke University
Medical Center, Durham - USA
| | - L.G. Milton
- Department of Surgery, Duke University
Medical Center, Durham - USA
| | - W.J. Koch
- Department of Surgery, Duke University
Medical Center, Durham - USA
| | - J.H. Lawson
- Department of Surgery, Duke University
Medical Center, Durham - USA
- Department of Pathology, Duke
University Medical Center, Durham - USA
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15
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Leong CM, Nackman GB, Wei T. Flow patterns through vascular graft models with and without cuffs. PLoS One 2018; 13:e0193304. [PMID: 29474415 PMCID: PMC5825106 DOI: 10.1371/journal.pone.0193304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 02/08/2018] [Indexed: 11/21/2022] Open
Abstract
The shape of a bypass graft plays an important role on its efficacy. Here, we investigated flow through two vascular graft designs-with and without cuff at the anastomosis. We conducted Digital Particle Image Velocimetry (DPIV) measurements to obtain the flow field information through these vascular grafts. Two pulsatile flow waveforms corresponding to cardiac cycles during the rest and the excitation states, with 10% and without retrograde flow out the proximal end of the native artery were examined. In the absence of retrograde flow, the straight end-to-side graft showed recirculation and stagnation regions that lasted throughout the full cardiac cycle with the stagnation region more pronounced in the excitation state. The contoured end-to-side graft had stagnation region that lasted only for a portion of the cardiac cycle and was less pronounced. With 10% retrograde flow, extended stagnation regions under both rest and excitation states for both bypass grafts were eliminated. Our results show that bypass graft designers need to consider both the type of flow waveform and presence of retrograde flow when sculpting an optimal bypass graft geometry.
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Affiliation(s)
- Chia Min Leong
- Department of Mechanical, Aerospace & Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York, United States of America
| | - Gary B. Nackman
- Division of Vascular Surgery, Robert Wood Johnson Medical School, New Brunswick, New Jersey, United States of America
| | - Timothy Wei
- Department of Mechanical and Materials Engineering, University of Nebraska, Lincoln, Nebraska, United States of America
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16
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Lioupis C, Mistry H, Junghans C, Haughey N, Freedman B, Tyrrell M, Valenti D. High Brachial Artery Bifurcation is Associated with Failure of Brachio-Cephalic Autologous Arteriovenous Fistulae. J Vasc Access 2018; 11:132-7. [DOI: 10.1177/112972981001100209] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Objective Although European Best Practice Guidelines on vascular access recommend universal pre-operative duplex scan in patients receiving brachio-cephalic (BC) arteriovenous fistulae (AVF), this is not widespread practice. Furthermore, cadaveric and angiographic studies suggest that variation in upper limb arterial anatomy is common. Our aim was to investigate the prevalence of high brachial artery bifurcation (HB) and its impact on BC AVF patency. Methods A retrospective analysis of consecutive autologous BC AVF created over an 18-month period (January 2008 to June 2009). Patients with high bifurcations identified at duplex scan were compared with a control group who had normal bifurcations. All patients were followed up at 1, 6 and 12 weeks post-operatively. The study endpoint was AVF patency. Results One hundred and five autologous BC AVF procedures were performed in our institution, of which 29 (27.6%) were identified as having a high brachial bifurcation on pre-operative duplex scan. The bifurcation was axillary in six patients and located at the proximal, middle and distal third of the humerus in nine, seven and seven patients, respectively. The actuarial functional patency rate was 53.2% (standard error = 9.6%) in the HB group and 76.2% (standard error = 4.9%) in the control group (log-rank test, p=0.027). Conclusions These data show that aberrant brachial artery anatomy is both common (12%) and a predictor of autologous BC AVF failure. These data support the universal use of pre-AVF duplex scanning.
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Affiliation(s)
- Christos Lioupis
- Department of Vascular Surgery, King's College Hospital, London - UK
| | - Hiren Mistry
- Department of Vascular Surgery, King's College Hospital, London - UK
| | | | - Niamh Haughey
- Department of Nephrology, King's College Hospital, London - UK
| | - Ben Freedman
- Vascular Laboratory, King's College Hospital, London - UK
| | - Mark Tyrrell
- Department of Vascular Surgery, King's College Hospital, London - UK
| | - Domenico Valenti
- Department of Vascular Surgery, King's College Hospital, London - UK
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17
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Vatankhah E, Prabhakaran MP, Ramakrishna S. Biomimetic microenvironment complexity to redress the balance between biodegradation and de novo matrix synthesis during early phase of vascular tissue engineering. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2017; 81:39-47. [DOI: 10.1016/j.msec.2017.06.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 05/29/2017] [Accepted: 06/28/2017] [Indexed: 01/12/2023]
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18
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Bai H, Hu H, Guo J, Ige M, Wang T, Isaji T, Kudze T, Liu H, Yatsula B, Hashimoto T, Xing Y, Dardik A. Polyester vascular patches acquire arterial or venous identity depending on their environment. J Biomed Mater Res A 2017; 105:3422-3431. [PMID: 28877393 PMCID: PMC5918420 DOI: 10.1002/jbm.a.36193] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 07/15/2017] [Accepted: 08/24/2017] [Indexed: 01/26/2023]
Abstract
Polyester is commonly used in vascular surgery for patch angioplasty and grafts. We hypothesized that polyester patches heal by infiltration of arterial or venous progenitor cells depending on the site of implantation. Polyester patches were implanted into the Wistar rat aorta or inferior vena cava and explanted on day 7 or 30. Neointima that formed on polyester patches was thicker in the venous environment compared to the amount that formed on patches in the arterial environment. Venous patches had more cell proliferation and greater numbers of VCAM-positive and CD68-positive cells, whereas arterial patches had greater numbers of vimentin-positive and alpha-actin-positive cells. Although there were similar numbers of endothelial progenitor cells in the neointimal endothelium, cells in the arterial patch were Ephrin-B2- and notch-4-positive while those in the venous patch were Eph-B4- and COUP-TFII-positive. Venous patches treated with an arteriovenous fistula had decreased neointimal thickness; neointimal endothelial cells expressed Ephrin-B2 and notch-4 in addition to Eph-B4 and COUP-TFII. Polyester patches in the venous environment acquire venous identity, whereas patches in the arterial environment acquire arterial identity; patches in the fistula environment acquire dual arterial-venous identity. These data suggest that synthetic patches heal by acquisition of identity of their environment. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3422-3431, 2017.
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Affiliation(s)
- Hualong Bai
- Department of Physiology, Basic Medical College of Zhengzhou University, Henan, China
- The Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut
- Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
- Department of Vascular Surgery, First Affiliated Hospital of Zhengzhou University, Henan, China
| | - Haidi Hu
- The Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut
- Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Jianming Guo
- The Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut
- Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Maryam Ige
- The Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut
- Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Tun Wang
- The Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut
- Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Toshihiko Isaji
- The Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut
- Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Tambudzai Kudze
- The Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut
- Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Haiyang Liu
- The Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut
- Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Bogdan Yatsula
- The Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut
- Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Takuya Hashimoto
- The Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut
- Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Ying Xing
- Department of Physiology, Basic Medical College of Zhengzhou University, Henan, China
| | - Alan Dardik
- The Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut
- Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
- Department of Surgery, VA Connecticut Healthcare System, West Haven, Connecticut
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19
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Linking gene dynamics to vascular hyperplasia - Toward a predictive model of vein graft adaptation. PLoS One 2017; 12:e0187606. [PMID: 29190638 PMCID: PMC5708843 DOI: 10.1371/journal.pone.0187606] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 10/20/2017] [Indexed: 11/25/2022] Open
Abstract
Reductionist approaches, where individual pieces of a process are examined in isolation, have been the mainstay of biomedical research. While these methods are effective in highly compartmentalized systems, they fail to account for the inherent plasticity and non-linearity within the signaling structure. In the current manuscript, we present the computational architecture for tracking an acute perturbation in a biologic system through a multiscale model that links gene dynamics to cell kinetics, with the overall goal of predicting tissue adaptation. Given the complexity of the genome, the problem is made tractable by clustering temporal changes in gene expression into unique patterns. These cluster elements form the core of an integrated network that serves as the driving force for the response of the biologic system. This modeling approach is illustrated using the clinical scenario of vein bypass graft adaptation. Vein segments placed in the arterial circulation for treatment of advanced occlusive disease can develop an aggressive hyperplastic response that narrows the lumen, reduces blood flow, and induces in situ thrombosis. Reducing this hyperplastic response has been a long-standing but unrealized goal of biologic researchers in the field. With repeated failures of single target therapies, the redundant response pathways are thought to be a fundamental issue preventing progress towards a solution. Using the current framework, we demonstrate how theoretical genomic manipulations can be introduced into the system to shift the adaptation to a more beneficial phenotype, where the hyperplastic response is mitigated and the risk of thrombosis reduced. Utilizing our previously published rabbit vein graft genomic data, where grafts were harvested at time points ranging from 2 hours to 28 days and under differential flow conditions, and a customized clustering algorithm, five gene clusters that differentiated the low flow (i.e., pro-hyperplastic) from high flow (i.e., anti-hyperplastic) response were identified. The current analysis advances these general associations to create a model that identifies those genes sets most likely to be of therapeutic benefit. Using this approach, we examine the range of potential opportunities for intervention via gene cluster over-expression or inhibition, delivered in isolation or combination, at the time of vein graft implantation.
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20
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Kleinert LB, Hoying JB, Williams SK. The Neointima Formed in Endothelial Cell Sodded ePTFE Vascular Grafts Results from Both Cellular-Hyperplasia and Extracellular-Hypertrophy. Cell Transplant 2017; 5:475-82. [PMID: 8800515 DOI: 10.1177/096368979600500406] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Endothelial cell transplantation onto polymeric vascular grafts results in the formation of a neointima. The formation of this neointima is often suggested to result from a chronic cellular hyperplasia where the terms intimal hyperplasia and intimal thickening are used interchangeably. While the formation of a midgraft neointima in sodded grafts involves a level of cell proliferation, the synthesis and deposition of extracellular matrix proteins is also a ubiquitous observation in these grafts. To assess the composition of midgraft neointima in sodded grafts, a morphometric method was developed to provide a differential quantitation of the cellular-hyperplastic and extracellular-hypertrophic elements of intimal thickening. The formed neointima on microvessel endothelial cell sodded and control (noncell-treated) ePTFE vascular grafts was quantified after 3, 12, and 52 wk of graft implantation in a canine carotid artery model. Midgraft sections of grafts were evaluated for both intimal thickness (IT) and cell density per unit volume and quantified using a PC-based image analysis program. Sodded grafts explanted at 3 wk exhibited an average neointimal cell density (3 × 109 cells/cm3; IT 30 μm) equivalent to cell densities observed in normal arterial media. After 12 wk the mean cell density approached a hyperplastic value (3.7 × 109 cells/cm3; IT 76 μm), while grafts explanted after 52 wk exhibited a mean cell density (2.8 × 109 cells/cm3; IT 30 μm) similar to 3-wk values. Control grafts that received no cells exhibited no midgraft cellular coverage. These results indicate that neointima formation in the midgraft region of sodded grafts occurred via mechanisms involving both a cellular hyperplasia and an extracellular hypertrophy. Differential responses occur presumably due to localized differences in cellular proliferation and cellular biosynthetic activity.
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Affiliation(s)
- L B Kleinert
- Department of Surgery, University of Arizona, Tucson 85724, USA
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21
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Bai H, Lee JS, Chen E, Wang M, Xing Y, Fahmy TM, Dardik A. Covalent modification of pericardial patches for sustained rapamycin delivery inhibits venous neointimal hyperplasia. Sci Rep 2017; 7:40142. [PMID: 28071663 PMCID: PMC5223139 DOI: 10.1038/srep40142] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 12/01/2016] [Indexed: 01/06/2023] Open
Abstract
Prosthetic grafts and patches are commonly used in cardiovascular surgery, however neointimal hyperplasia remains a significant concern, especially under low flow conditions. We hypothesized that delivery of rapamycin from nanoparticles (NP) covalently attached to patches allows sustained site-specific delivery of therapeutic agents targeted to inhibit localized neointimal hyperplasia. NP were covalently linked to pericardial patches using EDC/NHS chemistry and could deliver at least 360 ng rapamycin per patch without detectable rapamycin in serum; nanoparticles were detectable in the liver, kidney and spleen but no other sites within 24 hours. In a rat venous patch angioplasty model, control patches developed robust neointimal hyperplasia on the patch luminal surface characterized by Eph-B4-positive endothelium and underlying SMC and infiltrating cells such as macrophages and leukocytes. Patches delivering rapamycin developed less neointimal hyperplasia, less smooth muscle cell proliferation, and had fewer infiltrating cells but retained endothelialization. NP covalently linked to pericardial patches are a novel composite delivery system that allows sustained site-specific delivery of therapeutics; NP delivering rapamycin inhibit patch neointimal hyperplasia. NP linked to patches may represent a next generation of tissue engineered cardiovascular implants.
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Affiliation(s)
- Hualong Bai
- The Vascular Biology and Therapeutics Program and the Department of Surgery, Yale University School of Medicine, New Haven, CT, 06520, USA.,Basic Medical College of Zhengzhou University, Henan, China.,Department of Vascular Surgery, First Affiliated Hospital of Zhengzhou University, Henan, China
| | - Jung Seok Lee
- Department of Biomedical Engineering, Yale University, New Haven, CT, 06520, USA
| | - Elizabeth Chen
- The Vascular Biology and Therapeutics Program and the Department of Surgery, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Mo Wang
- The Vascular Biology and Therapeutics Program and the Department of Surgery, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Ying Xing
- Basic Medical College of Zhengzhou University, Henan, China
| | - Tarek M Fahmy
- Department of Biomedical Engineering, Yale University, New Haven, CT, 06520, USA.,Department of Immunobiology, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Alan Dardik
- The Vascular Biology and Therapeutics Program and the Department of Surgery, Yale University School of Medicine, New Haven, CT, 06520, USA.,Department of Surgery, VA Connecticut Healthcare System, West Haven, CT 06515, USA
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22
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Wang Y, Qiu J, Luo S, Xie X, Zheng Y, Zhang K, Ye Z, Liu W, Gregersen H, Wang G. High shear stress induces atherosclerotic vulnerable plaque formation through angiogenesis. Regen Biomater 2016; 3:257-67. [PMID: 27482467 PMCID: PMC4966293 DOI: 10.1093/rb/rbw021] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 05/15/2016] [Accepted: 05/19/2016] [Indexed: 12/12/2022] Open
Abstract
Rupture of atherosclerotic plaques causing thrombosis is the main cause of acute coronary syndrome and ischemic strokes. Inhibition of thrombosis is one of the important tasks developing biomedical materials such as intravascular stents and vascular grafts. Shear stress (SS) influences the formation and development of atherosclerosis. The current review focuses on the vulnerable plaques observed in the high shear stress (HSS) regions, which localizes at the proximal region of the plaque intruding into the lumen. The vascular outward remodelling occurs in the HSS region for vascular compensation and that angiogenesis is a critical factor for HSS which induces atherosclerotic vulnerable plaque formation. These results greatly challenge the established belief that low shear stress is important for expansive remodelling, which provides a new perspective for preventing the transition of stable plaques to high-risk atherosclerotic lesions.
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Affiliation(s)
- Yi Wang
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Juhui Qiu
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Shisui Luo
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Xiang Xie
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Yiming Zheng
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Kang Zhang
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Zhiyi Ye
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Wanqian Liu
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Hans Gregersen
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Guixue Wang
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
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23
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Bai H, Wang M, Foster TR, Hu H, He H, Hashimoto T, Hanisch JJ, Santana JM, Xing Y, Dardik A. Pericardial patch venoplasty heals via attraction of venous progenitor cells. Physiol Rep 2016; 4:4/12/e12841. [PMID: 27354544 PMCID: PMC4923240 DOI: 10.14814/phy2.12841] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 06/02/2016] [Indexed: 11/24/2022] Open
Abstract
Pericardial patches are commonly used during cardiovascular surgery to close blood vessels. In arteries, patches accumulate arterial progenitor cells; we hypothesized that venous patches would accumulate venous progenitor cells, in the absence of arterial pressure. We developed a novel rat inferior vena cava (IVC) venotomy model and repaired it with a pericardial patch. Cells infiltrated the patch to form a thick neointima by day 7; some cells were CD34+/VEGFR2+ and CD31+/Eph‐B4+ consistent with development of venous identity in the healing patch. Compared to arterial patches, the venous patches had increased neointimal thickness at day 7 without any pseudoaneurysms. Addition of an arteriovenous fistula (AVF) to increase blood flow on the patch resulted in reduced patch neointimal thickness and proliferation, but neointimal thickness was not reversible with AVF ligation. These results show that rat patch venoplasty is a novel model of aggressive venous neointimal hyperplasia.
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Affiliation(s)
- Hualong Bai
- The Vascular Biology and Therapeutics Program and the Department of Surgery, Yale University School of Medicine, New Haven, Connecticut Basic Medical College of Zhengzhou University, Henan, China Department of Vascular Surgery, First Affiliated Hospital of Zhengzhou University, Henan, China
| | - Mo Wang
- The Vascular Biology and Therapeutics Program and the Department of Surgery, Yale University School of Medicine, New Haven, Connecticut Department of Vascular Surgery, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Trenton R Foster
- The Vascular Biology and Therapeutics Program and the Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Haidi Hu
- The Vascular Biology and Therapeutics Program and the Department of Surgery, Yale University School of Medicine, New Haven, Connecticut Department of Surgery, VA Connecticut Healthcare System, West Haven, Connecticut
| | - Hao He
- The Vascular Biology and Therapeutics Program and the Department of Surgery, Yale University School of Medicine, New Haven, Connecticut Department of Vascular Surgery, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Takuya Hashimoto
- The Vascular Biology and Therapeutics Program and the Department of Surgery, Yale University School of Medicine, New Haven, Connecticut Department of Surgery, VA Connecticut Healthcare System, West Haven, Connecticut
| | - Jesse J Hanisch
- The Vascular Biology and Therapeutics Program and the Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Jeans M Santana
- The Vascular Biology and Therapeutics Program and the Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Ying Xing
- Basic Medical College of Zhengzhou University, Henan, China
| | - Alan Dardik
- The Vascular Biology and Therapeutics Program and the Department of Surgery, Yale University School of Medicine, New Haven, Connecticut Department of Surgery, VA Connecticut Healthcare System, West Haven, Connecticut
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Lin PH, Bush RL, Nguyen L, Guerrero MA, Chen C, Lumsden AB. Anastomotic Strategies to Improve Hemodialysis Access Patency—A Review. Vasc Endovascular Surg 2016; 39:135-42. [PMID: 15806274 DOI: 10.1177/153857440503900202] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The number of patients with end-stage renal disease (ESRD) who require maintenance hemodialysis has risen sharply in the past 2 decades. It is estimated that more than 60% of all patients with ESRD who require chronic hemodialysis are accessed through an arteriovenous fistula (AVF) or graft (AVG), and the incidence is increasing at a rate of 2% to 4% per year. The long-term patency rate of an upper extremity AVF or AVG for hemodialysis access remains suboptimal owing in part to progressive stenosis at the venous anastomosis. This article reviews the causative factors of dialysis access-related anastomotic stenosis, or intimal hyperplasia. This article also reviews the clinical experience of various anastomotic strategies to ameliorate the hemodynamic environment in an effort to improve the clinical outcome of hemodialysis access. These strategies include the use of (1) vein cuff at the expanded polytetrafluoroethylene (ePTFE)-venous anastomosis of AVG, (2) cuffed ePTFE dialysis AVG, and (3) anastomotic devices that create an interrupted anastomosis with staples or clips.
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Affiliation(s)
- Peter H Lin
- Division of Vascular Surgery and Endovascular Therapy, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston VAMC (112), 2002 Holcomb Blvd, Houston, TX 77030, USA.
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25
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Chandiwal A, Balasubramanian V, Baldwin ZK, Conte MS, Schwartz LB. Gene Therapy for the Extension of Vein Graft Patency: A Review. Vasc Endovascular Surg 2016; 39:1-14. [PMID: 15696243 DOI: 10.1177/153857440503900101] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The mainstay of treatment for long-segment small-vessel chronic occlusive disease not amenable to endovascular intervention remains surgical bypass grafting using autologous vein. The procedure is largely successful and the immediate operative results almost always favorable. However, the lifespan of a given vein graft is highly variable, and less than 50% will remain primarily patent after 5 years. The slow process of graft malfunction is a result of the vein's chronic maladaptive response to the systemic arterial environment, its primary component being the uncontrolled proliferation of vascular smooth muscle cells (SMCs). It has recently been suggested that this response might be attenuated through pre-implantation genetic modification of the vein, so-called gene therapy for the extension of vein graft patency. Gene therapy seems particularly well suited for the prevention or postponement of vein graft failure since: (1) the stimulation of SMC proliferation appears to largely be an early and transient process, matching the kinetics of current gene transfer technology; (2) most veins are relatively normal and free of disease at the time of bypass allowing for effective gene transfer using a variety of systems; and (3) the target tissue is directly accessible during operation because manipulation and irrigation of the vein is part of the normal workflow of the surgical procedure. This review briefly summarizes the current knowledge of the incidence and basic mechanisms of vein graft failure, the vector systems and molecular targets that have been proposed as possible pre-treatments, the results of experimental genetic modification of vein grafts, and the few available clinical studies of gene therapy for vascular proliferative disorders.
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Affiliation(s)
- Amito Chandiwal
- Section of Vascular Surgery, Department of Surgery, University of Chicago, IL 60637, USA
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26
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Ginestra PS, Ceretti E, Fiorentino A. Potential of modeling and simulations of bioengineered devices: Endoprostheses, prostheses and orthoses. Proc Inst Mech Eng H 2016; 230:607-38. [PMID: 27095509 DOI: 10.1177/0954411916643343] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 03/09/2016] [Indexed: 11/16/2022]
Abstract
Modeling and simulation of prosthetic devices are the new tools investigated for the production of total customized prostheses. Computational simulations are used to evaluate the geometrical and material designs of a device while assessing its mechanical behavior. Data acquisition through magnetic resonance imaging, computed tomography or laser scanning is the first step that gives information about the human anatomical structures; a file format has to be elaborated through computer-aided design software. Computer-aided design tools can be used to develop a device that respects the design requirements as, for instance, the human anatomy. Moreover, through finite element analysis software and the knowledge of loads and conditions the prostheses are supposed to face in vivo, it is possible to simulate, analyze and predict the mechanical behavior of the prosthesis and its effects on the surrounding tissues. Moreover, the simulations are useful to eventually improve the design (as geometry, materials, features) before the actual production of the device. This article presents an extensive analysis on the use of finite element modeling for the design, testing and development of prosthesis and orthosis devices.
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Affiliation(s)
- Paola Serena Ginestra
- Department of Mechanical and Industrial Engineering, University of Brescia, Brescia, Italy
| | - Elisabetta Ceretti
- Department of Mechanical and Industrial Engineering, University of Brescia, Brescia, Italy
| | - Antonio Fiorentino
- Department of Mechanical and Industrial Engineering, University of Brescia, Brescia, Italy
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Good BC, Deutsch S, Manning KB. Continuous and Pulsatile Pediatric Ventricular Assist Device Hemodynamics with a Viscoelastic Blood Model. Cardiovasc Eng Technol 2016; 7:23-43. [PMID: 26643646 PMCID: PMC4767652 DOI: 10.1007/s13239-015-0252-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 11/23/2015] [Indexed: 11/25/2022]
Abstract
To investigate the effects of pulsatile and continuous pediatric ventricular assist (PVAD) flow and pediatric blood viscoelasticity on hemodynamics in a pediatric aortic graft model. Hemodynamic parameters of pulsatility, along with velocity and wall shear stress (WSS), are analyzed and compared between Newtonian and viscoelastic blood models at a range of physiological pediatric hematocrits using computational fluid dynamics. Both pulsatile and continuous PVAD flow lead to a decrease in pulsatility (surplus hemodynamic energy, ergs/cm(3)) compared to healthy aortic flow but with continuous PVAD pulsatility up to 2.4 times lower than pulsatile PVAD pulsatility at each aortic outlet. Significant differences are also seen between the two flow modes in velocity and WSS. The higher velocity jet during systole with pulsatile flow leads to higher WSSs at the anastomotic toe and at the aortic branch bifurcations. The lower velocity but continuous flow jet leads to a much different flow field and higher WSSs into diastole. Under a range of physiological pediatric hematocrit (20-60%), both velocity and WSS can vary significantly with the higher hematocrit blood model generally leading to higher peak WSSs but also lower WSSs in regions of flow separation. The large decrease in pulsatility seen from continuous PVAD flow could lead to complications in pediatric vascular development while the high WSSs during peak systole from pulsatile PVAD flow could lead to blood damage. Both flow modes lead to similar regions prone to intimal hyperplasia resulting from low time-averaged WSS and high oscillatory shear index.
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Affiliation(s)
- Bryan C Good
- Department of Biomedical Engineering, The Pennsylvania State University, 205 Hallowell Building, University Park, PA, 16802, USA
| | - Steven Deutsch
- Department of Biomedical Engineering, The Pennsylvania State University, 205 Hallowell Building, University Park, PA, 16802, USA
| | - Keefe B Manning
- Department of Biomedical Engineering, The Pennsylvania State University, 205 Hallowell Building, University Park, PA, 16802, USA.
- Department of Surgery, Penn State Hershey Medical Center, Hershey, PA, 17033, USA.
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Xie D, Leng Y, Jing F, Huang N. A brief review of bio-tribology in cardiovascular devices. BIOSURFACE AND BIOTRIBOLOGY 2015. [DOI: 10.1016/j.bsbt.2015.11.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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Xue Y, Liu X, Sun A, Zhang P, Fan Y, Deng X. Hemodynamic Performance of a New Punched Stent Strut: A Numerical Study. Artif Organs 2015; 40:669-77. [PMID: 26581476 DOI: 10.1111/aor.12638] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Local flow disturbance by arterial stent struts has been shown to play an important role in stent thrombosis. To reduce the local flow disturbance near a stent strut, we proposed a new concept of stent design with small holes in the stent struts. The present study evaluated the new design numerically by comparing it with the traditional stent in terms of local hemodynamic parameters such as flow velocity, flow recirculation area, time-averaged wall shear stress (TAWSS), oscillating shear index (OSI), and relative residence time (RRT). The results demonstrated that when compared with the traditional strut, the new design could significantly enhance flow velocity and reduce the flow recirculation zone in the vicinity of the strut. Moreover, the new design would significantly elevate TAWSS and remarkably reduce OSI and RRT along the host arterial wall. In conclusion, the new design of stent struts with punched holes is advantageous over the traditional one in the aspect of improving local hemodynamics, which may reduce thrombosis formation and promote re-endothelialization after stenting.
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Affiliation(s)
- Yan Xue
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Xiao Liu
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Anqiang Sun
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Peng Zhang
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Yubo Fan
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Xiaoyan Deng
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
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Fulker D, Simmons A, Kabir K, Kark L, Barber T. The Hemodynamic Effects of Hemodialysis Needle Rotation and Orientation in an Idealized Computational Model. Artif Organs 2015; 40:185-9. [DOI: 10.1111/aor.12521] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- David Fulker
- School of Mechanical and Manufacturing Engineering; University of New South Wales; Sydney New South Wales Australia
| | - Anne Simmons
- School of Mechanical and Manufacturing Engineering; University of New South Wales; Sydney New South Wales Australia
| | - Kaveh Kabir
- School of Mechanical and Manufacturing Engineering; University of New South Wales; Sydney New South Wales Australia
| | - Lauren Kark
- Graduate School of Biomedical Engineering; University of New South Wales; Sydney New South Wales Australia
| | - Tracie Barber
- School of Mechanical and Manufacturing Engineering; University of New South Wales; Sydney New South Wales Australia
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Winkel LC, Hoogendoorn A, Xing R, Wentzel JJ, Van der Heiden K. Animal models of surgically manipulated flow velocities to study shear stress-induced atherosclerosis. Atherosclerosis 2015; 241:100-10. [PMID: 25969893 DOI: 10.1016/j.atherosclerosis.2015.04.796] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 04/12/2015] [Accepted: 04/22/2015] [Indexed: 10/23/2022]
Abstract
Atherosclerosis is a chronic inflammatory disease of the arterial tree that develops at predisposed sites, coinciding with locations that are exposed to low or oscillating shear stress. Manipulating flow velocity, and concomitantly shear stress, has proven adequate to promote endothelial activation and subsequent plaque formation in animals. In this article, we will give an overview of the animal models that have been designed to study the causal relationship between shear stress and atherosclerosis by surgically manipulating blood flow velocity profiles. These surgically manipulated models include arteriovenous fistulas, vascular grafts, arterial ligation, and perivascular devices. We review these models of manipulated blood flow velocity from an engineering and biological perspective, focusing on the shear stress profiles they induce and the vascular pathology that is observed.
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Affiliation(s)
- Leah C Winkel
- Department of Biomedical Engineering, Erasmus Medical Center, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Ayla Hoogendoorn
- Department of Biomedical Engineering, Erasmus Medical Center, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Ruoyu Xing
- Department of Biomedical Engineering, Erasmus Medical Center, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Jolanda J Wentzel
- Department of Biomedical Engineering, Erasmus Medical Center, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Kim Van der Heiden
- Department of Biomedical Engineering, Erasmus Medical Center, PO Box 2040, 3000 CA Rotterdam, The Netherlands.
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A novel peritoneum derived vascular prosthesis formed on a latex catheter in an SDF-1 chemokine enriched environment: a pilot study. Int J Artif Organs 2015; 38:89-95. [PMID: 25744192 DOI: 10.5301/ijao.5000396] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/19/2015] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Although saphenous vein grafts are widely used conduits for coronary artery bypass graft surgery, their clinical value remains limited due to high failure rates. The aim of the study was to evaluate feasibility, safety, and biocompatibility of peritoneal derived vascular grafts (PDVG) formed on a silicone-coated, latex, Foley catheter in a stromal cell-derived factor (SDF-1)- enriched environment. METHODS Foley catheters were implanted into the parietal wall of 8 sheep. After 21 days the peritoneal cavity was re-opened and the newly formed tissue fragments were harvested. The animals were randomly assigned into: (1) study group in which conduits were incubated in a solution containing SDF-1, (2) control group without SDF-1 incubation. Left carotid arteries were accessed and "end-to-side" anastomoses were performed. Biological materials for histological examination were taken at 4, 7, 10, and 14 days. RESULTS AND CONCLUSIONS The study proved safety, feasibility, and biocompatibility of PDVG formed on the basis of a silicone-coated, latex catheter in an SDF-1 chemokine-enriched environment. These biological grafts effectively integrated with the native high-pressure arterial environment in an ovine model and provided favorable vascular profile. The potential clinical value of this technology needs to be further elucidated in long-term preclinical and clinical studies.
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Baeyens N, Nicoli S, Coon BG, Ross TD, Van den Dries K, Han J, Lauridsen HM, Mejean CO, Eichmann A, Thomas JL, Humphrey JD, Schwartz MA. Vascular remodeling is governed by a VEGFR3-dependent fluid shear stress set point. eLife 2015; 4. [PMID: 25643397 PMCID: PMC4337723 DOI: 10.7554/elife.04645] [Citation(s) in RCA: 146] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Accepted: 02/01/2015] [Indexed: 12/23/2022] Open
Abstract
Vascular remodeling under conditions of growth or exercise, or during recovery from arterial restriction or blockage is essential for health, but mechanisms are poorly understood. It has been proposed that endothelial cells have a preferred level of fluid shear stress, or ‘set point’, that determines remodeling. We show that human umbilical vein endothelial cells respond optimally within a range of fluid shear stress that approximate physiological shear. Lymphatic endothelial cells, which experience much lower flow in vivo, show similar effects but at lower value of shear stress. VEGFR3 levels, a component of a junctional mechanosensory complex, mediate these differences. Experiments in mice and zebrafish demonstrate that changing levels of VEGFR3/Flt4 modulates aortic lumen diameter consistent with flow-dependent remodeling. These data provide direct evidence for a fluid shear stress set point, identify a mechanism for varying the set point, and demonstrate its relevance to vessel remodeling in vivo. DOI:http://dx.doi.org/10.7554/eLife.04645.001 Blood and lymphatic vessels remodel their shape, diameter and connections during development, and throughout life in response to growth, exercise and disease. This process is called vascular remodeling. The endothelial cells that line the inside of blood and lymphatic vessels are constantly exposed to the frictional force from flowing blood, termed fluid shear stress. Changes in shear stress are sensed by the endothelial cells, which trigger vascular remodeling to return the stress to the original level. It has been proposed that remodeling is governed by a preferred level of fluid shear stress, or set point, against which deviations in the shear stress are compared. Thus, changing the fluid flow through a blood vessel increases or decreases shear stress, which results in the vessel remodeling to restore the original level of shear stress. Like all remodeling, this process involves inflammation to recruit white blood cells, which assist with the process. Baeyens et al. investigated whether such a shear stress set point exists and what its biological basis might be using cultured endothelial cells from human umbilical veins. These cells remained stable and in a resting state when a particular level of shear stress was applied to them; above or below this shear stress level, the cells produced an inflammatory response like that seen during vascular remodeling. This suggests that these cells do indeed have a set point for shear stress. The same response occurred in human lymphatic endothelial cells, although in these cells the shear stress set point was much lower, correlating with the low flow in lymphatic vessels. Baeyens et al. then discovered that the shear stress set point is related to the level of a protein called VEGFR3 in the cells, which was recently found to participate in shear stress sensing. Endothelial cells from lymphatic vessels normally produce much greater quantities of VEGFR3 than those from blood vessels. Reducing the amount of VEGFR3 in lymphatic endothelial cells increased the set point shear stress, while increasing the levels in blood vessel cells decreased the set point. This suggests that the levels of this protein account for the difference in the response of these two cell types. Baeyens et al. then tested this pathway by reducing the levels of VEGFR3 in zebrafish embryos and in adult mice. In both animals, this caused arteries to narrow, showing that VEGFR3 levels also control sensitivity to shear stress—and hence vascular remodeling—inside living creatures. Understanding in detail how vascular remodeling is regulated could help improve treatments for a wide range of cardiovascular conditions. To do so, further work will be needed to develop methods to control the sensitivity of endothelial cells to shear stress and to identify other proteins that might specifically control the narrowing or the expansion of vessels in human patients. DOI:http://dx.doi.org/10.7554/eLife.04645.002
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Affiliation(s)
- Nicolas Baeyens
- Department of Internal Medicine, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, United States
| | - Stefania Nicoli
- Department of Internal Medicine, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, United States
| | - Brian G Coon
- Department of Internal Medicine, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, United States
| | - Tyler D Ross
- Department of Internal Medicine, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, United States
| | - Koen Van den Dries
- Department of Internal Medicine, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, United States
| | - Jinah Han
- Department of Internal Medicine, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, United States
| | - Holly M Lauridsen
- Department of Biomedical Engineering, Yale University School of Engineering and Applied Science, New Haven, United States
| | - Cecile O Mejean
- Department of Internal Medicine, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, United States
| | - Anne Eichmann
- Department of Internal Medicine, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, United States
| | - Jean-Leon Thomas
- Department of Neurology, Yale University School of Medicine, New Haven, United States
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University School of Engineering and Applied Science, New Haven, United States
| | - Martin A Schwartz
- Department of Internal Medicine, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, United States
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Abstract
Despite extensive efforts, most approaches to reduce arteriovenous (AV) access-related complications did not results in substantial improvement of AV access patency thus far. Part of this disappointing progress relates to incomplete understanding of the underlying pathophysiology of hemodialysis access failure. In order to unravel the pathophysiology of hemodialysis access failure, animal models that closely mimic human pathology are of utmost importance. Indeed, it is impossible to study the extremely complex response of the AV access at a molecular and cellular level in great detail in dialysis patients. Over the past decades, numerous animal models have been developed in an attempt to unravel the vascular pathology of AV access failure and to design new therapeutic strategies aimed to improve durability of these vascular conduits. While large animals such as pigs are suitable for intervention studies, murine models have the greatest potential to gain more insight in the molecular mechanisms underlying AV access failure due to the availability of transgenic mice. In the present review, we describe several existing models of AV access failure and discuss the advantages and limitations of these models.
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Qiu J, Zheng Y, Hu J, Liao D, Gregersen H, Deng X, Fan Y, Wang G. Biomechanical regulation of vascular smooth muscle cell functions: from in vitro to in vivo understanding. J R Soc Interface 2013; 11:20130852. [PMID: 24152813 DOI: 10.1098/rsif.2013.0852] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Vascular smooth muscle cells (VSMCs) have critical functions in vascular diseases. Haemodynamic factors are important regulators of VSMC functions in vascular pathophysiology. VSMCs are physiologically active in the three-dimensional matrix and interact with the shear stress sensor of endothelial cells (ECs). The purpose of this review is to illustrate how haemodynamic factors regulate VSMC functions under two-dimensional conditions in vitro or three-dimensional co-culture conditions in vivo. Recent advances show that high shear stress induces VSMC apoptosis through endothelial-released nitric oxide and low shear stress upregulates VSMC proliferation and migration through platelet-derived growth factor released by ECs. This differential regulation emphasizes the need to construct more actual environments for future research on vascular diseases (such as atherosclerosis and hypertension) and cardiovascular tissue engineering.
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Affiliation(s)
- Juhui Qiu
- Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Chongqing Engineering Laboratory in Vascular Implants, College of Bioengineering, Chongqing University, , Chongqing 400044, People's Republic of China
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36
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In-Stent Restenosis in the Superficial Femoral Artery. Ann Vasc Surg 2013; 27:510-24. [DOI: 10.1016/j.avsg.2012.09.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 08/07/2012] [Accepted: 09/16/2012] [Indexed: 11/20/2022]
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Leong CM, Voorhees A, Nackman GB, Wei T. Flow bioreactor design for quantitative measurements over endothelial cells using micro-particle image velocimetry. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:045109. [PMID: 23635234 DOI: 10.1063/1.4802681] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Mechanotransduction in endothelial cells (ECs) is a highly complex process through which cells respond to changes in hemodynamic loading by generating biochemical signals involving gene and protein expression. To study the effects of mechanical loading on ECs in a controlled fashion, different in vitro devices have been designed to simulate or replicate various aspects of these physiological phenomena. This paper describes the design, use, and validation of a flow chamber which allows for spatially and temporally resolved micro-particle image velocimetry measurements of endothelial surface topography and stresses over living ECs immersed in pulsatile flow. This flow chamber also allows the study of co-cultures (i.e., ECs and smooth muscle cells) and the effect of different substrates (i.e., coverslip and∕or polyethylene terepthalate (PET) membrane) on cellular response. In this report, the results of steady and pulsatile flow on fixed endothelial cells seeded on PET membrane and coverslip, respectively, are presented. Surface topography of ECs is computed from multiple two-dimensional flow measurements. The distributions of shear stress and wall pressure on each individual cell are also determined and the importance of both types of stress in cell remodeling is highlighted.
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Affiliation(s)
- Chia Min Leong
- Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, USA.
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Hwang M, Garbey M, Berceli SA, Wu R, Jiang Z, Tran-Son-Tay R. Rule-based model of vein graft remodeling. PLoS One 2013; 8:e57822. [PMID: 23533576 PMCID: PMC3606352 DOI: 10.1371/journal.pone.0057822] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 01/26/2013] [Indexed: 11/18/2022] Open
Abstract
When vein segments are implanted into the arterial system for use in arterial bypass grafting, adaptation to the higher pressure and flow of the arterial system is accomplished thorough wall thickening and expansion. These early remodeling events have been found to be closely coupled to the local hemodynamic forces, such as shear stress and wall tension, and are believed to be the foundation for later vein graft failure. To further our mechanistic understanding of the cellular and extracellular interactions that lead to global changes in tissue architecture, a rule-based modeling method is developed through the application of basic rules of behaviors for these molecular and cellular activities. In the current method, smooth muscle cell (SMC), extracellular matrix (ECM), and monocytes are selected as the three components that occupy the elements of a grid system that comprise the developing vein graft intima. The probabilities of the cellular behaviors are developed based on data extracted from in vivo experiments. At each time step, the various probabilities are computed and applied to the SMC and ECM elements to determine their next physical state and behavior. One- and two-dimensional models are developed to test and validate the computational approach. The importance of monocyte infiltration, and the associated effect in augmenting extracellular matrix deposition, was evaluated and found to be an important component in model development. Final model validation is performed using an independent set of experiments, where model predictions of intimal growth are evaluated against experimental data obtained from the complex geometry and shear stress patterns offered by a mid-graft focal stenosis, where simulation results show good agreements with the experimental data.
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Affiliation(s)
- Minki Hwang
- Departments of Mechanical & Aerospace Engineering, University of Florida, Gainesville, Florida, United States of America
| | - Marc Garbey
- Department of Computer Science, University of Houston, Houston, Texas, United States of America
| | - Scott A. Berceli
- Department of Surgery, University of Florida College of Medicine, Gainesville, Florida, United States of America
- Malcom Randall Veterans Affairs Medical Center, Gainesville, Florida, United States of America
| | - Rongling Wu
- Center for Statistical Genetics, Division of Biostatistics, Pennsylvania State University, Hershey, Pennsylvania, United States of America
| | - Zhihua Jiang
- Department of Surgery, University of Florida College of Medicine, Gainesville, Florida, United States of America
- Malcom Randall Veterans Affairs Medical Center, Gainesville, Florida, United States of America
| | - Roger Tran-Son-Tay
- Departments of Mechanical & Aerospace Engineering, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
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Moodley L, Franz T, Human P, Wolf MF, Bezuidenhout D, Scherman J, Zilla P. Protective constriction of coronary vein grafts with knitted nitinol. Eur J Cardiothorac Surg 2013; 44:64-71. [PMID: 23295444 DOI: 10.1093/ejcts/ezs670] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Different flow patterns and shear forces were shown to cause significantly more luminal narrowing and neointimal tissue proliferation in coronary than in infrainguinal vein grafts. As constrictive external mesh support of vein grafts led to the complete suppression of intimal hyperplasia (IH) in infrainguinal grafts, we investigated whether mesh constriction is equally effective in the coronary position. METHODS Eighteen senescent Chacma baboons (28.8 ± 3.6 kg) received aorto-coronary bypass grafts to the left anterior descending artery (LAD). Three groups of saphenous vein grafts were compared: untreated controls (CO); fibrin sealant-sprayed controls (CO + FS) and nitinol mesh-constricted grafts (ME + FS). Meshes consisted of pulse-compliant, knitted nitinol (eight needles; 50 μm wire thickness; 3.4 mm resting inner diameter, ID) spray attached to the vein grafts with FS. After 180 days of implantation, luminal dimensions and IH were analysed using post-explant angiography and macroscopic and histological image analysis. RESULTS At implantation, the calibre mismatch between control grafts and the LAD expressed as cross-sectional quotient (Qc) was pronounced [Qc = 0.21 ± 0.07 (CO) and 0.18 ± 0.05 (CO + FS)]. Mesh constriction resulted in a 29 ± 7% reduction of the outer diameter of the vein grafts from 5.23 ± 0.51 to 3.68 ± 0 mm, significantly reducing the calibre discrepancy to a Qc of 0.41 ± 0.17 (P < 0.02). After 6 months of implantation, explant angiography showed distinct luminal irregularities in control grafts (ID difference between widest and narrowest segment 74 ± 45%), while diameter variations were mild in mesh-constricted grafts. In all control grafts, thick neointimal tissue was present [600 ± 63 μm (CO); 627 ± 204 μm (CO + FS)] as opposed to thin, eccentric layers of 249 ± 83 μm in mesh-constricted grafts (ME + FS; P < 0.002). The total wall thickness had increased by 363 ± 39% (P < 0.00001) in CO and 312 ± 61% (P < 0.00001) in CO + FS vs 82 ± 61% in ME + FS (P < 0.007). CONCLUSIONS In a senescent non-human primate model for coronary artery bypass grafts, constrictive, external mesh support of saphenous veins with knitted nitinol prevented focal, irregular graft narrowing and suppressed neointimal tissue proliferation by a factor of 2.5. The lower degree of suppression of IH compared with previous infrainguinal grafts coincided with a lesser reduction of calibre mismatch in the coronary grafts.
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Affiliation(s)
- Loven Moodley
- Chris Barnard Department of Cardiothoracic Surgery, University of Cape Town, Cape Town, South Africa
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40
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McGah PM, Leotta DF, Beach KW, Zierler RE, Riley JJ, Aliseda A. Hemodynamic conditions in a failing peripheral artery bypass graft. J Vasc Surg 2012; 56:403-9. [PMID: 22551907 PMCID: PMC3408774 DOI: 10.1016/j.jvs.2012.01.045] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 12/07/2011] [Accepted: 01/14/2012] [Indexed: 01/05/2023]
Abstract
OBJECTIVE The mechanisms of restenosis in autogenous vein bypass grafts placed for peripheral artery disease are not completely understood. We investigated the role of hemodynamic stress in a case study of a revised bypass graft that failed due to restenosis. METHODS The morphology of the lumen was reconstructed from a custom three-dimensional ultrasound system. Scans were taken at 1, 6, and 16 months after a patch angioplasty procedure. Computational hemodynamic simulations of the patient-specific model provided the blood flow features and the hemodynamic stresses on the vessel wall at the three times studied. RESULTS The vessel was initially free of any detectable lesions, but a 60% diameter-reducing stenosis developed during the 16-month study interval. As determined from the simulations, chaotic and recirculating flow occurred downstream of the stenosis due to the sudden widening of the lumen at the patch location. Curvature and a sudden increase in the lumen cross-sectional area induced these flow features that are hypothesized to be conducive to intimal hyperplasia. Favorable agreement was found between simulation results and in vivo Doppler ultrasound velocity measurements. CONCLUSIONS Transitional and chaotic flow occurs at the site of the revision, inducing a complex pattern of wall shear as computed with the hemodynamic simulations. This supports the hypothesis that the hemodynamic stresses in the revised segment, produced by the coupling of vessel geometry and chaotic flow, led to the intimal hyperplasia and restenosis of the graft.
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Affiliation(s)
- Patrick M McGah
- Department of Mechanical Engineering, University of Washington, Seattle, Wash., USA.
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41
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Patient-specific multiscale modeling of blood flow for coronary artery bypass graft surgery. Ann Biomed Eng 2012; 40:2228-42. [PMID: 22539149 DOI: 10.1007/s10439-012-0579-3] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 04/14/2012] [Indexed: 12/27/2022]
Abstract
We present a computational framework for multiscale modeling and simulation of blood flow in coronary artery bypass graft (CABG) patients. Using this framework, only CT and non-invasive clinical measurements are required without the need to assume pressure and/or flow waveforms in the coronaries and we can capture global circulatory dynamics. We demonstrate this methodology in a case study of a patient with multiple CABGs. A patient-specific model of the blood vessels is constructed from CT image data to include the aorta, aortic branch vessels (brachiocephalic artery and carotids), the coronary arteries and multiple bypass grafts. The rest of the circulatory system is modeled using a lumped parameter network (LPN) 0 dimensional (0D) system comprised of resistances, capacitors (compliance), inductors (inertance), elastance and diodes (valves) that are tuned to match patient-specific clinical data. A finite element solver is used to compute blood flow and pressure in the 3D (3 dimensional) model, and this solver is implicitly coupled to the 0D LPN code at all inlets and outlets. By systematically parameterizing the graft geometry, we evaluate the influence of graft shape on the local hemodynamics, and global circulatory dynamics. Virtual manipulation of graft geometry is automated using Bezier splines and control points along the pathlines. Using this framework, we quantify wall shear stress, wall shear stress gradients and oscillatory shear index for different surgical geometries. We also compare pressures, flow rates and ventricular pressure-volume loops pre- and post-bypass graft surgery. We observe that PV loops do not change significantly after CABG but that both coronary perfusion and local hemodynamic parameters near the anastomosis region change substantially. Implications for future patient-specific optimization of CABG are discussed.
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Hsu S, Chu JS, Chen FF, Wang A, Li S. Effects of Fluid Shear Stress on a Distinct Population of Vascular Smooth Muscle Cells. Cell Mol Bioeng 2011; 4:627-636. [PMID: 22924082 DOI: 10.1007/s12195-011-0205-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Vascular smooth muscle cells (SMCs) are a major cell type involved in vascular remodeling. The various developmental origins of SMCs such as neural crest and mesoderm result in heterogeneity of SMCs, which plays an important role in the development of vascular remodeling and diseases. Upon vascular injury, SMCs are exposed to blood flow and subjected to fluid shear stress. Previous studies have shown that fluid shear stress inhibits SMC proliferation. However, the effect of shear stress on the subpopulation of SMCs from specific developmental origin and vascular bed is not well understood. Here we investigated how shear stress regulates human aortic SMCs positive for neural crest markers. DNA microarray analysis showed that shear stress modulates the expression of genes involved in cell proliferation, matrix synthesis, cell signaling, transcription and cytoskeleton organization. Further studies demonstrated that shear stress induced SMC proliferation and cyclin D1, downregulated cell cycle inhibitor p21, and activated Akt pathway. Inhibition of PI-3 kinase blocked these shear stress-induced changes. These results suggest that SMCs with neural crest characteristics may respond to shear stress in a different manner. This finding has significant implications in the remodeling and diseases of blood vessels.
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Affiliation(s)
- Steven Hsu
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, USA
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43
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McGah PM, Leotta DF, Beach KW, Riley JJ, Aliseda A. A longitudinal study of remodeling in a revised peripheral artery bypass graft using 3D ultrasound imaging and computational hemodynamics. J Biomech Eng 2011; 133:041008. [PMID: 21428682 PMCID: PMC3205960 DOI: 10.1115/1.4003622] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We report a study of the role of hemodynamic shear stress in the remodeling and failure of a peripheral artery bypass graft. Three separate scans of a femoral to popliteal above-knee bypass graft were taken over the course of a 16 month period following a revision of the graft. The morphology of the lumen is reconstructed from data obtained by a custom 3D ultrasound system. Numerical simulations are performed with the patient-specific geometries and physiologically realistic flow rates. The ultrasound reconstructions reveal two significant areas of remodeling: a stenosis with over 85% reduction in area, which ultimately caused graft failure, and a poststenotic dilatation or widening of the lumen. Likewise, the simulations reveal a complicated hemodynamic environment within the graft. Preliminary comparisons with in vivo velocimetry also showed qualitative agreement with the flow dynamics observed in the simulations. Two distinct flow features are discerned and are hypothesized to directly initiate the observed in vivo remodeling. First, a flow separation occurs at the stenosis. A low shear recirculation region subsequently develops distal to the stenosis. The low shear region is thought to be conducive to smooth muscle cell proliferation and intimal growth. A poststenotic jet issues from the stenosis and subsequently impinges onto the lumen wall. The lumen dilation is thought to be a direct result of the high shear stress and high frequency pressure fluctuations associated with the jet impingement.
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Affiliation(s)
- Patrick M McGah
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195, USA.
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Short-term effects of double-layer autologous vein graft on restraint of excessive distension and alleviation of neointimal hyperplasia in a porcine saphenous vein graft model. Heart Vessels 2010; 26:190-5. [DOI: 10.1007/s00380-010-0034-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Accepted: 02/12/2010] [Indexed: 10/18/2022]
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45
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Franz T, Human P, Dobner S, Reddy BD, Black M, Ilsley H, Wolf MF, Bezuidenhout D, Moodley L, Zilla P. Tailored sizes of constrictive external vein meshes for coronary artery bypass surgery. Biomaterials 2010; 31:9301-9. [DOI: 10.1016/j.biomaterials.2010.08.054] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 08/24/2010] [Indexed: 10/19/2022]
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Desai M, Mirzay-Razzaz J, von Delft D, Sarkar S, Hamilton G, Seifalian AM. Inhibition of neointimal formation and hyperplasia in vein grafts by external stent/sheath. Vasc Med 2010; 15:287-97. [DOI: 10.1177/1358863x10366479] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Synthetic and to a lesser extent vein graft failure is still a major problem in the treatment of peripheral arterial disease, with neointimal hyperplasia being the main cause for graft occlusion in the medium and long term. This review aims to establish the current status of external stents or sheaths in the prevention of intimal hyperplasia in small diameter (< 6 mm) vein grafts.
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Affiliation(s)
- Mital Desai
- Centre for Nanotechnology and Regenerative Medicine, Division of Surgery & Interventional Science, University College London, London, UK, Cardiovascular Haemodynamic Group, University College London, London, UK
| | - Jalaledin Mirzay-Razzaz
- Centre for Nanotechnology and Regenerative Medicine, Division of Surgery & Interventional Science, University College London, London, UK, Cardiovascular Haemodynamic Group, University College London, London, UK
| | - Dirk von Delft
- Christiaan Barnard Division of Cardiothoracic Surgery, University of Cape Town, Cape Town, South Africa
| | - Sandip Sarkar
- Centre for Nanotechnology and Regenerative Medicine, Division of Surgery & Interventional Science, University College London, London, UK
| | - George Hamilton
- Vascular Unit, Royal Free Hampstead NHS Trust Hospital, London, UK
| | - Alexander M Seifalian
- Centre for Nanotechnology and Regenerative Medicine, Division of Surgery & Interventional Science, University College London, London, UK, Cardiovascular Haemodynamic Group, University College London, London, UK,
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47
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Owens CD. Adaptive changes in autogenous vein grafts for arterial reconstruction: clinical implications. J Vasc Surg 2009; 51:736-46. [PMID: 19837532 DOI: 10.1016/j.jvs.2009.07.102] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2009] [Revised: 07/20/2009] [Accepted: 07/24/2009] [Indexed: 01/22/2023]
Abstract
For patients with the most severe manifestations of lower extremity arterial occlusive disease, bypass surgery using autogenous vein has been the most durable reconstruction. However, the incidence of bypass graft stenosis and graft failure remains substantial and wholesale improvements in patency are lacking. One potential explanation is that stenosis arises not only from over exuberant intimal hyperplasia, but also due to insufficient adaptation or remodeling of the vein to the arterial environment. Although in vivo human studies are difficult to conduct, recent advances in imaging technology have made possible a more comprehensive structural examination of vein bypass maturation. This review summarizes recent translational efforts to understand the structural and functional properties of human vein grafts and places it within the context of the rich existing literature of vein graft failure.
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Affiliation(s)
- Christopher D Owens
- Division of Vascular and Endovascular Surgery, University of California San Francisco, San Francisco, CA 94143, USA.
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48
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Grus T, Lindner J, Vidim T, Tosovsky J, Matecha J, Rohn V, Lambert L, Grusova G. The Anastomosis Angle Is a Key to Improved Long-Term Patency of Proximal Femoropopliteal Bypass. Ann Vasc Surg 2009; 23:598-605. [DOI: 10.1016/j.avsg.2009.06.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2008] [Revised: 03/10/2009] [Accepted: 06/08/2009] [Indexed: 10/20/2022]
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49
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Abarbanell AM, Herrmann JL, Weil BR, Wang Y, Tan J, Moberly SP, Fiege JW, Meldrum DR. Animal models of myocardial and vascular injury. J Surg Res 2009; 162:239-49. [PMID: 20053409 DOI: 10.1016/j.jss.2009.06.021] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2009] [Revised: 06/06/2009] [Accepted: 06/16/2009] [Indexed: 01/09/2023]
Abstract
Over the past century, numerous animal models have been developed in an attempt to understand myocardial and vascular injury. However, the successful translation of results observed in animals to human therapy remains low. To understand this problem, we present several animal models of cardiac and vascular injury that are of particular relevance to the cardiac or vascular surgeon. We also explore the potential clinical implications and limitations of each model with respect to the human disease state. Our results underscore the concept that animal research requires an in-depth understanding of the model, animal physiology, and the potential confounding factors. Future outcome analyses with standardized animal models may improve translation of animal research from the bench to the bedside.
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Affiliation(s)
- Aaron M Abarbanell
- Department of Surgery, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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50
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Clinical and translational implications of the caveolin gene family: lessons from mouse models and human genetic disorders. J Transl Med 2009; 89:614-23. [PMID: 19333235 PMCID: PMC2796209 DOI: 10.1038/labinvest.2009.23] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Here we review the clinical and translational implications of the caveolin gene family for understanding the pathogenesis of human diseases, including breast and prostate cancers, pulmonary hypertension, cardiomyopathy, diabetes, and muscular dystrophy. Detailed phenotypic analysis of caveolin knockout mice has served to highlight the crucial role of a caveolin deficiency in the pathogenesis of many human disease processes. Mutations in the human caveolin genes are associated with a number of established genetic disorders (such as breast cancer, lipodystrophy, muscular dystrophy, and cardiomyopathy), making the caveolins important and novel targets for drug development. The implementation of new strategies for caveolin replacement therapy-including caveolin mimetic peptides-is ongoing.
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