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Jiang D, Robinson AJ, Nkansah A, Leung J, Guo L, Maas SA, Weiss JA, Cosgriff-Hernandez EM, Timmins LH. A computational framework to optimize the mechanical behavior of synthetic vascular grafts. J Mech Behav Biomed Mater 2024; 163:106847. [PMID: 39708758 DOI: 10.1016/j.jmbbm.2024.106847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2024] [Revised: 11/11/2024] [Accepted: 11/30/2024] [Indexed: 12/23/2024]
Abstract
The failure of synthetic small-diameter vascular grafts has been attributed to a mismatch in the compliance between the graft and native artery, driving mechanisms that promote thrombosis and neointimal hyperplasia. Additionally, the buckling of grafts results in large deformations that can lead to device failure. Although design features can be added to lessen the buckling potential (e.g., reinforcing coil), the addition is detrimental to decreasing compliance. Herein, we developed a novel finite element (FE) framework to inform vascular graft design by evaluating compliance and resistance to buckling. A batch-processing scheme iterated across the multi-dimensional design parameter space, which included three parameters: coil thickness, modulus, and spacing - generating 100 unique designs. FE models were created for each coil-reinforced graft design to simulate pressurization, axial buckling, and bent buckling, and results were analyzed to quantify compliance, buckling load, and kink radius, respectively. Validation of the FE models demonstrated that model predictions agreed with experimental observations for compliance (r = 0.99), buckling load (r = 0.89), and kink resistance (r = 0.97). Model predictions demonstrated a broad range of values for compliance (1.1-7.9 %/mmHg × 10-2), buckling load (0.28-0.84 N), and kink radius (6-10 mm) across the design parameter space. Subsequently, data for each design parameter combination were optimized (i.e., minimized) to identify candidate graft designs with promising mechanical properties. Our model-directed framework successfully elucidated the complex mechanical determinants of graft performance, established structure-property relationships, and identified vascular graft designs with optimal mechanical properties, potentially improving clinical outcomes by addressing device failure.
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Affiliation(s)
- David Jiang
- Department of Biomedical Engineering, The University of Utah, 36 S Wasatch Dr, Salt Lake City, UT, 84112, USA; Department of Biomedical Engineering, Texas A&M University, 101 Bizzell St, College Station, TX, 77843, USA.
| | - Andrew J Robinson
- Department of Biomedical Engineering, The University of Texas at Austin, 107 W Dean Keeton Street, Austin, TX, 78712, USA.
| | - Abbey Nkansah
- Department of Biomedical Engineering, The University of Texas at Austin, 107 W Dean Keeton Street, Austin, TX, 78712, USA.
| | - Jonathan Leung
- Department of Biomedical Engineering, The University of Texas at Austin, 107 W Dean Keeton Street, Austin, TX, 78712, USA.
| | - Leopold Guo
- Department of Biomedical Engineering, The University of Texas at Austin, 107 W Dean Keeton Street, Austin, TX, 78712, USA.
| | - Steve A Maas
- Scientific Computing and Imaging Institute, The University of Utah, 72 Central Campus Dr, Salt Lake City, UT, 84112, USA.
| | - Jeffrey A Weiss
- Department of Biomedical Engineering, The University of Utah, 36 S Wasatch Dr, Salt Lake City, UT, 84112, USA; Scientific Computing and Imaging Institute, The University of Utah, 72 Central Campus Dr, Salt Lake City, UT, 84112, USA; Department of Orthopaedics, The University of Utah, 590 Wakara Way, Salt Lake City, UT, 84108, USA.
| | - Elizabeth M Cosgriff-Hernandez
- Department of Biomedical Engineering, The University of Texas at Austin, 107 W Dean Keeton Street, Austin, TX, 78712, USA.
| | - Lucas H Timmins
- Department of Biomedical Engineering, The University of Utah, 36 S Wasatch Dr, Salt Lake City, UT, 84112, USA; Department of Biomedical Engineering, Texas A&M University, 101 Bizzell St, College Station, TX, 77843, USA; Scientific Computing and Imaging Institute, The University of Utah, 72 Central Campus Dr, Salt Lake City, UT, 84112, USA; School of Engineering Medicine, Texas A&M University, 1020 Holcombe Blvd., Houston, TX, 77030, USA; Department of Multidisciplinary Engineering, Texas A&M University, 101 Bizzell St, College Station, TX, 77843, USA; Department of Cardiovascular Sciences, Houston Methodist Academic Institute, 6565 Fannin Street, Houston, TX, 77030, USA.
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Breeyear JH, Hellwege JN, Schroeder PH, House JS, Poisner HM, Mitchell SL, Charest B, Khakharia A, Basnet TB, Halladay CW, Reaven PD, Meigs JB, Rhee MK, Sun Y, Lynch MG, Bick AG, Wilson OD, Hung AM, Nealon CL, Iyengar SK, Rotroff DM, Buse JB, Leong A, Mercader JM, Sobrin L, Brantley MA, Peachey NS, Motsinger-Reif AA, Wilson PW, Sun YV, Giri A, Phillips LS, Edwards TL. Adaptive selection at G6PD and disparities in diabetes complications. Nat Med 2024; 30:2480-2488. [PMID: 38918629 PMCID: PMC11555759 DOI: 10.1038/s41591-024-03089-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 05/21/2024] [Indexed: 06/27/2024]
Abstract
Diabetes complications occur at higher rates in individuals of African ancestry. Glucose-6-phosphate dehydrogenase deficiency (G6PDdef), common in some African populations, confers malaria resistance, and reduces hemoglobin A1c (HbA1c) levels by shortening erythrocyte lifespan. In a combined-ancestry genome-wide association study of diabetic retinopathy, we identified nine loci including a G6PDdef causal variant, rs1050828 -T (Val98Met), which was also associated with increased risk of other diabetes complications. The effect of rs1050828 -T on retinopathy was fully mediated by glucose levels. In the years preceding diabetes diagnosis and insulin prescription, glucose levels were significantly higher and HbA1c significantly lower in those with versus without G6PDdef. In the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial, participants with G6PDdef had significantly higher hazards of incident retinopathy and neuropathy. At the same HbA1c levels, G6PDdef participants in both ACCORD and the Million Veteran Program had significantly increased risk of retinopathy. We estimate that 12% and 9% of diabetic retinopathy and neuropathy cases, respectively, in participants of African ancestry are due to this exposure. Across continentally defined ancestral populations, the differences in frequency of rs1050828 -T and other G6PDdef alleles contribute to disparities in diabetes complications. Diabetes management guided by glucose or potentially genotype-adjusted HbA1c levels could lead to more timely diagnoses and appropriate intensification of therapy, decreasing the risk of diabetes complications in patients with G6PDdef alleles.
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Affiliation(s)
- Joseph H Breeyear
- Biostatistics and Computational Biology Branch, Division of Intramural Research, National Institute of Environmental Health Sciences, Durham, NC, USA
- Division of Epidemiology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- VA Tennessee Valley Healthcare System (626), Nashville, TN, USA
| | - Jacklyn N Hellwege
- VA Tennessee Valley Healthcare System (626), Nashville, TN, USA
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Genetics Institute, Vanderbilt University, Nashville, TN, USA
| | - Philip H Schroeder
- Program in Metabolism, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Diabetes Unit, Endocrine Division, Department of Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - John S House
- Biostatistics and Computational Biology Branch, Division of Intramural Research, National Institute of Environmental Health Sciences, Durham, NC, USA
| | - Hannah M Poisner
- Vanderbilt Genetics Institute, Vanderbilt University, Nashville, TN, USA
| | - Sabrina L Mitchell
- VA Tennessee Valley Healthcare System (626), Nashville, TN, USA
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Brian Charest
- Massachusetts Veterans Epidemiology Research and Information Center, Boston, MA, USA
| | - Anjali Khakharia
- Atlanta VA Medical Center, Decatur, GA, USA
- Department of Medicine and Geriatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - Til B Basnet
- Division of Epidemiology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Division of Quantitative Sciences, Department of Obstetrics and Gynecology, Vanderbilt University Medical Center, Nashville, TN, USA
| | | | - Peter D Reaven
- Phoenix VA Health Care System, Phoenix, AZ, USA
- College of Medicine, University of Arizona, Phoenix, AZ, USA
| | - James B Meigs
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
- Division of General Internal Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Mary K Rhee
- Atlanta VA Medical Center, Decatur, GA, USA
- Division of Endocrinology, Metabolism, and Lipids, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
| | - Yang Sun
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
- Veterans Administration Palo Alto Health Care System, Palo Alto, California, USA
| | | | - Alexander G Bick
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Genetics Institute, Vanderbilt University, Nashville, TN, USA
| | - Otis D Wilson
- VA Tennessee Valley Healthcare System (626), Nashville, TN, USA
| | - Adriana M Hung
- VA Tennessee Valley Healthcare System (626), Nashville, TN, USA
| | - Cari L Nealon
- Eye Clinic, VA Northeast Ohio Healthcare System, Cleveland, OH, USA
- Department of Ophthalmology & Visual Sciences, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Sudha K Iyengar
- Research Service, VA Northeast Ohio Healthcare System, Cleveland, OH, USA
- Department of Population and Quantitative Health Sciences, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Daniel M Rotroff
- Department of Quantitative Health Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
- Endocrinology and Metabolism Institute, Cleveland Clinic, Cleveland, OH, USA
- Center for Quantitative Metabolic Research, Cleveland Clinic, Cleveland, OH, USA
| | - John B Buse
- Division of Endocrinology & Metabolism, Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Aaron Leong
- Program in Metabolism, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Diabetes Unit, Endocrine Division, Department of Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
- Division of General Internal Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Josep M Mercader
- Program in Metabolism, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Diabetes Unit, Endocrine Division, Department of Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
- Department of Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Lucia Sobrin
- Department of Ophthalmology, Mass Eye and Ear Infirmary, Harvard Medical School, Boston, MA, USA
| | - Milam A Brantley
- VA Tennessee Valley Healthcare System (626), Nashville, TN, USA
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Neal S Peachey
- Research Service, VA Northeast Ohio Healthcare System, Cleveland, OH, USA
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, USA
| | - Alison A Motsinger-Reif
- Biostatistics and Computational Biology Branch, Division of Intramural Research, National Institute of Environmental Health Sciences, Durham, NC, USA
| | - Peter W Wilson
- Atlanta VA Medical Center, Decatur, GA, USA
- Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
| | - Yan V Sun
- Atlanta VA Medical Center, Decatur, GA, USA
- Department of Epidemiology, Emory University Rollins School of Public Health, Atlanta, GA, USA
- Department of Biomedical Informatics, Emory University School of Medicine, Atlanta, GA, USA
| | - Ayush Giri
- VA Tennessee Valley Healthcare System (626), Nashville, TN, USA.
- Vanderbilt Genetics Institute, Vanderbilt University, Nashville, TN, USA.
- Division of Quantitative Sciences, Department of Obstetrics and Gynecology, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Lawrence S Phillips
- Atlanta VA Medical Center, Decatur, GA, USA
- Division of Endocrinology, Metabolism, and Lipids, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
| | - Todd L Edwards
- Division of Epidemiology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
- VA Tennessee Valley Healthcare System (626), Nashville, TN, USA.
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Ghorbani A, Mirzaali MJ, Roebroek T, Coulais C, Bonn D, van der Linden E, Habibi M. Suppressing torsional buckling in auxetic meta-shells. Nat Commun 2024; 15:6999. [PMID: 39143043 PMCID: PMC11324657 DOI: 10.1038/s41467-024-51104-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Accepted: 07/29/2024] [Indexed: 08/16/2024] Open
Abstract
Take a thin cylindrical shell and twist it; it will buckle immediately. Such unavoidable torsional buckling can lead to systemic failure, for example by disrupting the blood flow through arteries. In this study, we prevent this torsional buckling instability using a combination of auxeticity and orthotropy in cylindrical metamaterial shells with a holey pattern. When the principal axes of the orthotropic meta-shell are relatively aligned with that of the compressive component of the applied stress during twisting, the meta-shell uniformly shrinks in the radial direction as a result of a local buckling instability. This shrinkage coincides with a softening-stiffening transition that leads to ordered stacking of unit cells along the compressive component of the applied stress. These transitions due to local instabilities circumvent the usual torsional instability even under a large twist angle. This study highlights the potential of tailoring anisotropy and programming instabilities in metamaterials, with potential applications in designing mechanical elements for soft robotics, biomechanics or fluidics. As an example of such applications, we demonstrate soft torsional compressor for generating pulsatile flows through a torsion release mechanism.
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Affiliation(s)
- Aref Ghorbani
- Laboratory of Physics and Physical Chemistry of Foods, Wageningen University, 6708 WG, Wageningen, The Netherlands.
| | - Mohammad J Mirzaali
- Department of Biomechanical Engineering, Delft University of Technology, 2628 CD, Delft, The Netherlands
| | - Tobias Roebroek
- Laboratory of Physics and Physical Chemistry of Foods, Wageningen University, 6708 WG, Wageningen, The Netherlands
| | - Corentin Coulais
- Institute of Physics, University of Amsterdam, 1098 XH, Amsterdam, The Netherlands
| | - Daniel Bonn
- Institute of Physics, University of Amsterdam, 1098 XH, Amsterdam, The Netherlands
| | - Erik van der Linden
- Laboratory of Physics and Physical Chemistry of Foods, Wageningen University, 6708 WG, Wageningen, The Netherlands
| | - Mehdi Habibi
- Laboratory of Physics and Physical Chemistry of Foods, Wageningen University, 6708 WG, Wageningen, The Netherlands.
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4
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Donmazov S, Piskin S, Gölcez T, Kul D, Arnaz A, Pekkan K. Mechanical characterization and torsional buckling of pediatric cardiovascular materials. Biomech Model Mechanobiol 2024; 23:845-860. [PMID: 38361084 PMCID: PMC11101351 DOI: 10.1007/s10237-023-01809-z] [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: 07/17/2023] [Accepted: 12/22/2023] [Indexed: 02/17/2024]
Abstract
In complex cardiovascular surgical reconstructions, conduit materials that avoid possible large-scale structural deformations should be considered. A fundamental mode of mechanical complication is torsional buckling which occurs at the anastomosis site due to the mechanical instability, leading surgical conduit/patch surface deformation. The objective of this study is to investigate the torsional buckling behavior of commonly used materials and to develop a practical method for estimating the critical buckling rotation angle under physiological intramural vessel pressures. For this task, mechanical tests of four clinically approved materials, expanded polytetrafluoroethylene (ePTFE), Dacron, porcine and bovine pericardia, commonly used in pediatric cardiovascular surgeries, are conducted (n = 6). Torsional buckling initiation tests with n = 4 for the baseline case (L = 7.5 cm) and n = 3 for the validation of ePTFE (L = 15 cm) and Dacron (L = 15 cm and L = 25 cm) for each are also conducted at low venous pressures. A practical predictive formulation for the buckling potential is proposed using experimental observations and available theory. The relationship between the critical buckling rotation angle and the lumen pressure is determined by balancing the circumferential component of the compressive principal stress with the shear stress generated by the modified critical buckling torque, where the modified critical buckling torque depends linearly on the lumen pressure. While the proposed technique successfully predicted the critical rotation angle values lying within two standard deviations of the mean in the baseline case for all four materials at all lumen pressures, it could reliably predict the critical buckling rotation angles for ePTFE and Dacron samples of length 15 cm with maximum relative errors of 31% and 38%, respectively, in the validation phase. However, the validation of the performance of the technique demonstrated lower accuracy for Dacron samples of length 25 cm at higher pressure levels of 12 mmHg and 15 mmHg. Applicable to all surgical materials, this formulation enables surgeons to assess the torsional buckling potential of vascular conduits noninvasively. Bovine pericardium has been found to exhibit the highest stability, while Dacron (the lowest) and porcine pericardium have been identified as the least stable with the (unitless) torsional buckling resistance constants, 43,800, 12,300 and 14,000, respectively. There was no significant difference between ePTFE and Dacron, and between porcine and bovine pericardia. However, both porcine and bovine pericardia were found to be statistically different from ePTFE and Dacron individually (p < 0.0001). ePTFE exhibited highly nonlinear behavior across the entire strain range [0, 0.1] (or 10% elongation). The significant differences among the surgical materials reported here require special care in conduit construction and anastomosis design.
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Affiliation(s)
- Samir Donmazov
- Department of Mathematics, University of Kentucky, Kentucky, 40506, USA
| | - Senol Piskin
- Department of Mechanical Engineering, Istinye University, Istanbul, 34010, Turkey
| | - Tansu Gölcez
- Department of Bio-Medical Science and Engineering, Koc University, Istanbul, Turkey
| | - Demet Kul
- Department of Cellular and Molecular Medicine, Koc University, Istanbul, Turkey
| | - Ahmet Arnaz
- Department of Cardiovascular Surgery, School of Medicine, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey
| | - Kerem Pekkan
- Department of Mechanical Engineering, Koc University, Sariyer, Istanbul, Turkey.
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van de Velde L, Groot Jebbink E, Jain K, Versluis M, Reijnen MMPJ. Lesion Eccentricity Plays a Key Role in Determining the Pressure Gradient of Serial Stenotic Lesions: Results from a Computational Hemodynamics Study. Cardiovasc Intervent Radiol 2024; 47:533-542. [PMID: 38565717 DOI: 10.1007/s00270-024-03708-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 03/06/2024] [Indexed: 04/04/2024]
Abstract
PURPOSE In arterial disease, the presence of two or more serial stenotic lesions is common. For mild lesions, it is difficult to predict whether their combined effect is hemodynamically significant. This study assessed the hemodynamic significance of idealized serial stenotic lesions by simulating their hemodynamic interaction in a computational flow model. MATERIALS AND METHODS Flow was simulated with SimVascular software in 34 serial lesions, using moderate (15 mL/s) and high (30 mL/s) flow rates. Combinations of one concentric and two eccentric lesions, all 50% area reduction, were designed with variations in interstenotic distance and in relative direction of eccentricity. Fluid and fluid-structure simulations were performed to quantify the combined pressure gradient. RESULTS At a moderate flow rate, the combined pressure gradient of two lesions ranged from 3.8 to 7.7 mmHg, which increased to a range of 12.5-24.3 mmHg for a high flow rate. Eccentricity caused an up to two-fold increase in pressure gradient relative to concentric lesions. At a high flow rate, the combined pressure gradient for serial eccentric lesions often exceeded the sum of the individual lesions. The relative direction of eccentricity altered the pressure gradient by 15-25%. The impact of flow pulsatility and wall deformability was minor. CONCLUSION This flow simulation study revealed that lesion eccentricity is an adverse factor in the hemodynamic significance of isolated stenotic lesions and in serial stenotic lesions. Two 50% lesions that are individually non-significant can combine more often than thought to hemodynamic significance in hyperemic conditions.
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Affiliation(s)
- L van de Velde
- Multi-Modality Medical Imaging M3i Group, TechMed Centre, University of Twente, Drienerlolaan 5, 7522 NB, Enschede, The Netherlands.
- Department of Surgery, Rijnstate, Arnhem, The Netherlands.
- Physics of Fluids Group, TechMed Centre, University of Twente, Enschede, The Netherlands.
| | - E Groot Jebbink
- Multi-Modality Medical Imaging M3i Group, TechMed Centre, University of Twente, Drienerlolaan 5, 7522 NB, Enschede, The Netherlands
- Physics of Fluids Group, TechMed Centre, University of Twente, Enschede, The Netherlands
| | - K Jain
- Department of Thermal and Fluid Engineering, University of Twente, Enschede, The Netherlands
| | - M Versluis
- Physics of Fluids Group, TechMed Centre, University of Twente, Enschede, The Netherlands
| | - M M P J Reijnen
- Multi-Modality Medical Imaging M3i Group, TechMed Centre, University of Twente, Drienerlolaan 5, 7522 NB, Enschede, The Netherlands
- Department of Surgery, Rijnstate, Arnhem, The Netherlands
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Drees L, Schneider S, Riedel D, Schuh R, Behr M. The proteolysis of ZP proteins is essential to control cell membrane structure and integrity of developing tracheal tubes in Drosophila. eLife 2023; 12:e91079. [PMID: 37872795 PMCID: PMC10597583 DOI: 10.7554/elife.91079] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 09/20/2023] [Indexed: 10/25/2023] Open
Abstract
Membrane expansion integrates multiple forces to mediate precise tube growth and network formation. Defects lead to deformations, as found in diseases such as polycystic kidney diseases, aortic aneurysms, stenosis, and tortuosity. We identified a mechanism of sensing and responding to the membrane-driven expansion of tracheal tubes. The apical membrane is anchored to the apical extracellular matrix (aECM) and causes expansion forces that elongate the tracheal tubes. The aECM provides a mechanical tension that balances the resulting expansion forces, with Dumpy being an elastic molecule that modulates the mechanical stress on the matrix during tracheal tube expansion. We show in Drosophila that the zona pellucida (ZP) domain protein Piopio interacts and cooperates with the ZP protein Dumpy at tracheal cells. To resist shear stresses which arise during tube expansion, Piopio undergoes ectodomain shedding by the Matriptase homolog Notopleural, which releases Piopio-Dumpy-mediated linkages between membranes and extracellular matrix. Failure of this process leads to deformations of the apical membrane, tears the apical matrix, and impairs tubular network function. We also show conserved ectodomain shedding of the human TGFβ type III receptor by Notopleural and the human Matriptase, providing novel findings for in-depth analysis of diseases caused by cell and tube shape changes.
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Affiliation(s)
- Leonard Drees
- Research Group Molecular Organogenesis, Department of Molecular Developmental Biology, Max Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Susi Schneider
- Cell biology, Institute for Biology, Leipzig UniversityLeipzigGermany
| | - Dietmar Riedel
- Facility for electron microscopy, Max Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Reinhard Schuh
- Research Group Molecular Organogenesis, Department of Molecular Developmental Biology, Max Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Matthias Behr
- Cell biology, Institute for Biology, Leipzig UniversityLeipzigGermany
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7
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Laudato M, Mosca R, Mihaescu M. Buckling critical pressures in collapsible tubes relevant for biomedical flows. Sci Rep 2023; 13:9298. [PMID: 37291334 PMCID: PMC10250313 DOI: 10.1038/s41598-023-36513-6] [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: 04/12/2023] [Accepted: 06/05/2023] [Indexed: 06/10/2023] Open
Abstract
The behaviour of collapsed or stenotic vessels in the human body can be studied by means of simplified geometries like a collapsible tube. The objective of this work is to determine the value of the buckling critical pressure of a collapsible tube by employing Landau's theory of phase transition. The methodology is based on the implementation of an experimentally validated 3D numerical model of a collapsible tube. The buckling critical pressure is estimated for different values of geometric parameters of the system by treating the relation between the intramural pressure and the area of the central cross-section as the order parameter function of the system. The results show the dependence of the buckling critical pressures on the geometric parameters of a collapsible tube. General non-dimensional equations for the buckling critical pressures are derived. The advantage of this method is that it does not require any geometric assumption, but it is solely based on the observation that the buckling of a collapsible tube can be treated as a second-order phase transition. The investigated geometric and elastic parameters are sensible for biomedical application, with particular interest to the study of the bronchial tree under pathophysiological conditions like asthma.
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Affiliation(s)
- Marco Laudato
- Department of Engineering Mechanics, FLOW Research Center, KTH Royal Institute of Technology, 10044, Stockholm, Sweden.
| | - Roberto Mosca
- Department of Engineering Mechanics, FLOW Research Center, KTH Royal Institute of Technology, 10044, Stockholm, Sweden
| | - Mihai Mihaescu
- Department of Engineering Mechanics, FLOW Research Center, KTH Royal Institute of Technology, 10044, Stockholm, Sweden
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8
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Karageorgos GM, Kemper P, Lee C, Weber R, Kwon N, Meshram N, Mobadersany N, Grondin J, Marshall RS, Miller EC, Konofagou EE. Adaptive Wall Shear Stress Imaging in Phantoms, Simulations and In Vivo. IEEE Trans Biomed Eng 2023; 70:154-165. [PMID: 35776824 PMCID: PMC10103592 DOI: 10.1109/tbme.2022.3186854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
WSS measurement is challenging since it requires sensitive flow measurements at a distance close to the wall. The aim of this study is to develop an ultrasound imaging technique which combines vector flow imaging with an unsupervised data clustering approach that automatically detects the region close to the wall with optimally linear flow profile, to provide direct and robust WSS estimation. The proposed technique was evaluated in phantoms, mimicking normal and atherosclerotic vessels, and spatially registered Fluid Structure Interaction (FSI) simulations. A relative error of 6.7% and 19.8% was obtained for peak systolic (WSSPS) and end diastolic (WSSED) WSS in the straight phantom, while in the stenotic phantom, a good similarity was found between measured and simulated WSS distribution, with a correlation coefficient, R, of 0.89 and 0.85 for WSSPS and WSSED, respectively. Moreover, the feasibility of the technique to detect pre-clinical atherosclerosis was tested in an atherosclerotic swine model. Six swines were fed atherogenic diet, while their left carotid artery was ligated in order to disturb flow patterns. Ligated arterial segments that were exposed to low WSSPS and WSS characterized by high frequency oscillations at baseline, developed either moderately or highly stenotic plaques (p < 0.05). Finally, feasibility of the technique was demonstrated in normal and atherosclerotic human subjects. Atherosclerotic carotid arteries with low stenosis had lower WSSPS as compared to control subjects (p < 0.01), while in one subject with high stenosis, elevated WSS was found on an arterial segment, which coincided with plaque rupture site, as determined through histological examination.
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9
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Naumann J, Koppe N, Thome UH, Laube M, Zink M. Mechanical properties of the premature lung: From tissue deformation under load to mechanosensitivity of alveolar cells. Front Bioeng Biotechnol 2022; 10:964318. [PMID: 36185437 PMCID: PMC9523442 DOI: 10.3389/fbioe.2022.964318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 08/23/2022] [Indexed: 11/16/2022] Open
Abstract
Many preterm infants require mechanical ventilation as life-saving therapy. However, ventilation-induced overpressure can result in lung diseases. Considering the lung as a viscoelastic material, positive pressure inside the lung results in increased hydrostatic pressure and tissue compression. To elucidate the effect of positive pressure on lung tissue mechanics and cell behavior, we mimic the effect of overpressure by employing an uniaxial load onto fetal and adult rat lungs with different deformation rates. Additionally, tissue expansion during tidal breathing due to a negative intrathoracic pressure was addressed by uniaxial tension. We found a hyperelastic deformation behavior of fetal tissues under compression and tension with a remarkable strain stiffening. In contrast, adult lungs exhibited a similar response only during compression. Young’s moduli were always larger during tension compared to compression, while only during compression a strong deformation-rate dependency was found. In fact, fetal lung tissue under compression showed clear viscoelastic features even for small strains. Thus, we propose that the fetal lung is much more vulnerable during inflation by mechanical ventilation compared to normal inspiration. Electrophysiological experiments with different hydrostatic pressure gradients acting on primary fetal distal lung epithelial cells revealed that the activity of the epithelial sodium channel (ENaC) and the sodium-potassium pump (Na,K-ATPase) dropped during pressures of 30 cmH2O. Thus, pressures used during mechanical ventilation might impair alveolar fluid clearance important for normal lung function.
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Affiliation(s)
- Jonas Naumann
- Research Group Biotechnology and Biomedicine, Peter-Debye-Institute for Soft Matter Physics, Leipzig University, Leipzig, Germany
| | - Nicklas Koppe
- Research Group Biotechnology and Biomedicine, Peter-Debye-Institute for Soft Matter Physics, Leipzig University, Leipzig, Germany
| | - Ulrich H. Thome
- Center for Pediatric Research Leipzig, Department of Pediatrics, Division of Neonatology, Leipzig University, Leipzig, Germany
| | - Mandy Laube
- Center for Pediatric Research Leipzig, Department of Pediatrics, Division of Neonatology, Leipzig University, Leipzig, Germany
| | - Mareike Zink
- Research Group Biotechnology and Biomedicine, Peter-Debye-Institute for Soft Matter Physics, Leipzig University, Leipzig, Germany
- *Correspondence: Mareike Zink,
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10
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Yuan Z, Ren Y, Shafiq M, Chen Y, Tang H, Li B, El-Newehy M, El-Hamshary H, Morsi Y, Zheng H, Mo X. Converging 3D Printing and Electrospinning: Effect of Poly(l-lactide)/Gelatin Based Short Nanofibers Aerogels on Tracheal Regeneration. Macromol Biosci 2021; 22:e2100342. [PMID: 34706143 DOI: 10.1002/mabi.202100342] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/13/2021] [Indexed: 12/28/2022]
Abstract
Recently, various tissue engineering based strategies have been pursued for the regeneration of tracheal tissues. However, previously developed tracheal scaffolds do not accurately mimic the microstructure and mechanical behavior of the native trachea, which restrict their clinical translation. Here, tracheal scaffolds are fabricated by using 3D printing and short nanofibers (SF) dispersion of poly(l-lactide)/gelatin (0.5-1.5 wt%) to afford tracheal constructs. The results display that the scaffolds containing 1.0 wt % of SF exhibit low density, good water absorption capacity, reasonable degradation rate, and stable mechanical properties, which were comparable to the native trachea. Moreover, the designed scaffolds possess good biocompatibility and promote the growth and infiltration of chondrocytes in vitro. The biocompatibility of tracheal scaffolds is further assessed after subcutaneous implantation in mice for up to 4 and 8 weeks. Histological assessment of tracheal constructs explanted at week 4 shows that scaffolds can maintain their structural integrity and support the formation of neo-vessels. Furthermore, cell-scaffold constructs gradually form cartilage-like tissues, which mature with time. Collectively, these engineered tracheal scaffolds not only possess appropriate mechanical properties to afford a stabilized structure but also a biomimetic extracellular matrix-like structure to accomplish tissue regeneration, which may have broad implications for tracheal regeneration.
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Affiliation(s)
- Zhengchao Yuan
- Shanghai Engineering Research Center of Nano-Biomaterials and Regenerative Medicine, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai, 201620, P. R. China
| | - Yijiu Ren
- Department of Thoracic Surgery, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, 200433, P. R. China
| | - Muhammad Shafiq
- Shanghai Engineering Research Center of Nano-Biomaterials and Regenerative Medicine, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai, 201620, P. R. China
| | - Yujie Chen
- Shanghai Engineering Research Center of Nano-Biomaterials and Regenerative Medicine, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai, 201620, P. R. China
| | - Hai Tang
- Department of Thoracic Surgery, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, 200433, P. R. China
| | - Baojie Li
- Shanghai Engineering Research Center of Nano-Biomaterials and Regenerative Medicine, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai, 201620, P. R. China
| | - Mohamed El-Newehy
- Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia
| | - Hany El-Hamshary
- Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia
| | - Yosry Morsi
- Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Boroondara, VIC, 3122, Australia
| | - Hui Zheng
- Department of Thoracic Surgery, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, 200433, P. R. China
| | - Xiumei Mo
- Shanghai Engineering Research Center of Nano-Biomaterials and Regenerative Medicine, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai, 201620, P. R. China
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11
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Gou K, Baek S, Lutnesky MMF, Han HC. Growth-profile configuration for specific deformations of tubular organs: A study of growth-induced thinning and dilation of the human cervix. PLoS One 2021; 16:e0255895. [PMID: 34379659 PMCID: PMC8357173 DOI: 10.1371/journal.pone.0255895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 07/26/2021] [Indexed: 12/02/2022] Open
Abstract
Growth is a significant factor that results in deformations of tubular organs, and particular deformations associated with growth enable tubular organs to perform certain physiological functions. Configuring growth profiles that achieve particular deformation patterns is critical for analyzing potential pathological conditions and for developing corresponding clinical treatments for tubular organ dysfunctions. However, deformation-targeted growth is rarely studied. In this article, the human cervix during pregnancy is studied as an example to show how cervical thinning and dilation are generated by growth. An advanced hyperelasticity theory called morphoelasticity is employed to model the deformations, and a growth tensor is used to represent growth in three principle directions. The computational results demonstrate that both negative radial growth and positive circumferential growth facilitate thinning and dilation. Modeling such mixed growth represents an advancement beyond commonly used uniform growth inside tissues to study tubular deformations. The results reveal that complex growth may occur inside tissues to achieve certain tubular deformations. Integration of further biochemical and cellular activities that initiate and mediate such complex growth remains to be explored.
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Affiliation(s)
- Kun Gou
- Department of Mathematical, Physical, and Engineering Sciences, Texas A&M University-San Antonio, San Antonio, Texas, United States of America
- * E-mail:
| | - Seungik Baek
- Department of Mechanical Engineering, Michigan State University, East Lansing, Michigan, United States of America
| | - Marvin M. F. Lutnesky
- Department of Life Sciences, Texas A&M University-San Antonio, San Antonio, Texas, United States of America
| | - Hai-Chao Han
- Department of Mechanical Engineering, The University of Texas at San Antonio, San Antonio, Texas, United States of America
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12
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Humphrey JD. Constrained Mixture Models of Soft Tissue Growth and Remodeling - Twenty Years After. JOURNAL OF ELASTICITY 2021; 145:49-75. [PMID: 34483462 PMCID: PMC8415366 DOI: 10.1007/s10659-020-09809-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 12/29/2020] [Indexed: 05/06/2023]
Abstract
Soft biological tissues compromise diverse cell types and extracellular matrix constituents, each of which can possess individual natural configurations, material properties, and rates of turnover. For this reason, mixture-based models of growth (changes in mass) and remodeling (change in microstructure) are well-suited for studying tissue adaptations, disease progression, and responses to injury or clinical intervention. Such approaches also can be used to design improved tissue engineered constructs to repair, replace, or regenerate tissues. Focusing on blood vessels as archetypes of soft tissues, this paper reviews a constrained mixture theory introduced twenty years ago and explores its usage since by contrasting simulations of diverse vascular conditions. The discussion is framed within the concept of mechanical homeostasis, with consideration of solid-fluid interactions, inflammation, and cell signaling highlighting both past accomplishments and future opportunities as we seek to understand better the evolving composition, geometry, and material behaviors of soft tissues under complex conditions.
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Affiliation(s)
- J D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT 06520 USA
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13
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Chalin D, Bureau C, Parmeggiani A, Rochal S, Kissa K, Golushko I. Modeling and live imaging of mechanical instabilities in the zebrafish aorta during hematopoiesis. Sci Rep 2021; 11:9316. [PMID: 33927284 PMCID: PMC8085226 DOI: 10.1038/s41598-021-88667-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 04/01/2021] [Indexed: 01/27/2023] Open
Abstract
All blood cells originate from hematopoietic stem/progenitor cells (HSPCs). HSPCs are formed from endothelial cells (ECs) of the dorsal aorta (DA), via endothelial-to-hematopoietic transition (EHT). The zebrafish is a primary model organism to study the process in vivo. While the role of mechanical stress in controlling gene expression promoting cell differentiation is actively investigated, mechanisms driving shape changes of the DA and individual ECs remain poorly understood. We address this problem by developing a new DA micromechanical model and applying it to experimental data on zebrafish morphogenesis. The model considers the DA as an isotropic tubular membrane subjected to hydrostatic blood pressure and axial stress. The DA evolution is described as a movement in the dimensionless controlling parameters space: normalized hydrostatic pressure and axial stress. We argue that HSPC production is accompanied by two mechanical instabilities arising in the system due to the plane stress in the DA walls and show how a complex interplay between mechanical forces in the system drives the emerging morphological changes.
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Affiliation(s)
- Dmitrii Chalin
- Research and Education Center "Materials", Don State Technical University, 1 Gagarin Square, Rostov-on-Don, 344000, Russia
| | - Charlotte Bureau
- LPHI, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Andrea Parmeggiani
- LPHI, University of Montpellier, CNRS, INSERM, Montpellier, France.,Laboratoire Charles Coulomb, University of Montpellier, CNRS, Montpellier, France
| | - Sergei Rochal
- Faculty of Physics, Southern Federal University, Zorge 5, Rostov-on-Don, 344090, Russian Federation
| | - Karima Kissa
- LPHI, University of Montpellier, CNRS, INSERM, Montpellier, France.
| | - Ivan Golushko
- Research and Education Center "Materials", Don State Technical University, 1 Gagarin Square, Rostov-on-Don, 344000, Russia.
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14
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Jia H, Chen B, Li D, Jin Y. Strategy of boundary discretization in numerical simulation of laser propagation in skin tissue with vascular lesions. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2021; 18:2455-2472. [PMID: 33892555 DOI: 10.3934/mbe.2021125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Understanding light propagation in skin tissues with complex blood vessels can help improve clinical efficacy in the laser treatment of cutaneous vascular lesions. The voxel-based Monte Carlo (VMC) algorithm with simple blood vessel geometry is commonly used in studying the law of light propagation in tissues. However, unavoidable errors are expected in VMC because of the zigzag polygonal interface. A tetrahedron-based Monte Carlo with extended boundary condition (TMCE) solver is developed to discretize complex tissue boundaries accurately. Tetrahedra are generated along the interface, resulting in a polyhedron approximation to match the real interface. A comparison between TMCE and VMC shows neglected differences in the overall distribution of energy deposition of different models, but poor adaptability of the curved tissue interface in VMC leads to a higher energy deposition error than TMCE in a mostly deposited region in blood vessels. Replacing the real blood vessel with a cylinder-shaped vessel shows an error lower than that caused by VMC. Statistical significance analysis of energy deposition by TMCE shows that mean curvature has stronger relationship with energy deposition than the Gaussian curvature, which indicates the importance of this geometric parameter in predicting photon behavior in vascular lesions.
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Affiliation(s)
- Hao Jia
- State-Province Joint Engineering Lab of Fluid Transmission System Technology, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Bin Chen
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Dong Li
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Yuzhen Jin
- State-Province Joint Engineering Lab of Fluid Transmission System Technology, Zhejiang Sci-Tech University, Hangzhou 310018, China
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15
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van Kampen KA, Olaret E, Stancu IC, Moroni L, Mota C. Controllable four axis extrusion-based additive manufacturing system for the fabrication of tubular scaffolds with tailorable mechanical properties. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2020; 119:111472. [PMID: 33321595 DOI: 10.1016/j.msec.2020.111472] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/21/2020] [Accepted: 07/13/2020] [Indexed: 11/17/2022]
Abstract
Many tubular tissues such as blood vessels and trachea can suffer long-segmental defects through trauma and disease. With current limitations in the use of autologous grafts, the need for a synthetic substitute is of continuous interest as possible alternatives. Fabrication of these tubular organs is commonly done with techniques such as electrospinning and melt electrowriting using a rotational collector. Current additive manufacturing (AM) systems do not commonly implement the use of a rotational axis, which limits their application for the fabrication of tubular scaffolds. In this study, a four axis extrusion-based AM system similar to fused deposition modeling (FDM) has been developed to create tubular hollow scaffolds. A rectangular and a diamond pore design were further investigated for mechanical characterization, as a standard and a biomimicry pore geometry respectively. We demonstrated that in the radial compression mode the diamond pore design had a higher Young's modulus (19,8 ± 0,7 MPa compared to 2,8 ± 0,5 MPa), while in the longitudinal tensile mode the rectangular pore design had a higher Young's modulus (5,8 ± 0,2 MPa compared to 0,1 ± 0,01 MPa). Three-point bending analyses revealed that the diamond pore design is more resistant to luminal collapse compared to the rectangular design. This data showed that by changing the scaffold pore design, a wide range of mechanical properties could be obtained. Furthermore, a full control over scaffold design and geometry can be achieved with the developed 4-axis extrusion-based system, which has not been reported with other techniques. This flexibility allow the manufacturing of scaffolds for diverse tubular tissue regeneration applications by designing suitable deposition patterns to match their mechanical pre-requisites.
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Affiliation(s)
- Kenny A van Kampen
- Department of Complex Tissue Regeneration, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Universiteitsingel 40, 6229ER Maastricht, the Netherlands
| | - Elena Olaret
- Advanced Polymer Materials Group, University Politehnica of Bucharest, 1-7 Gh. Polizu Street, 011061 Bucharest, Romania
| | - Izabela-Cristina Stancu
- Advanced Polymer Materials Group, University Politehnica of Bucharest, 1-7 Gh. Polizu Street, 011061 Bucharest, Romania
| | - Lorenzo Moroni
- Department of Complex Tissue Regeneration, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Universiteitsingel 40, 6229ER Maastricht, the Netherlands
| | - Carlos Mota
- Department of Complex Tissue Regeneration, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Universiteitsingel 40, 6229ER Maastricht, the Netherlands.
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16
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Vilela MA, Amaral CE, Ferreira MAT. Retinal vascular tortuosity: Mechanisms and measurements. Eur J Ophthalmol 2020; 31:1497-1506. [PMID: 33307777 DOI: 10.1177/1120672120979907] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Retinal vessel tortuosity has been used in the diagnosis and management of different clinical situations. Notwithstanding, basic concepts, standards and tools of measurement, reliable normative data and clinical applications have many gaps or points of divergence. In this review we discuss triggering causes of retinal vessel tortuosity and resources used to assess and quantify it, as well as current limitations.
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Affiliation(s)
- Manuel Ap Vilela
- Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil
| | - Carlos Ev Amaral
- Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil
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17
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Weiss D, Cavinato C, Gray A, Ramachandra AB, Avril S, Humphrey JD, Latorre M. Mechanics-driven mechanobiological mechanisms of arterial tortuosity. SCIENCE ADVANCES 2020; 6:6/49/eabd3574. [PMID: 33277255 PMCID: PMC7821897 DOI: 10.1126/sciadv.abd3574] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 10/22/2020] [Indexed: 05/04/2023]
Abstract
Arterial tortuosity manifests in many conditions, including hypertension, genetic mutations predisposing to thoracic aortopathy, and vascular aging. Despite evidence that tortuosity disrupts efficient blood flow and that it may be an important clinical biomarker, underlying mechanisms remain poorly understood but are widely appreciated to be largely biomechanical. Many previous studies suggested that tortuosity may arise via an elastic structural buckling instability, but the novel experimental-computational approach used here suggests that tortuosity arises from mechanosensitive, cell-mediated responses to local aberrations in the microstructural integrity of the arterial wall. In particular, computations informed by multimodality imaging show that aberrations in elastic fiber integrity, collagen alignment, and collagen turnover can lead to a progressive loss of structural stability that entrenches during the development of tortuosity. Interpreted in this way, microstructural defects or irregularities of the arterial wall initiate the condition and hypertension is a confounding factor.
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Affiliation(s)
- Dar Weiss
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Cristina Cavinato
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Authia Gray
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | | | - Stephane Avril
- Mines Saint-Etienne, Centre CIS, INSERM, U 1059 Sainbiose University of Lyon, Univ Jean Monnet, Saint-Etienne, France
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA.
| | - Marcos Latorre
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
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18
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Nama N, Aguirre M, Humphrey JD, Figueroa CA. A nonlinear rotation-free shell formulation with prestressing for vascular biomechanics. Sci Rep 2020; 10:17528. [PMID: 33067508 PMCID: PMC7567841 DOI: 10.1038/s41598-020-74277-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 09/28/2020] [Indexed: 02/01/2023] Open
Abstract
We implement a nonlinear rotation-free shell formulation capable of handling large deformations for applications in vascular biomechanics. The formulation employs a previously reported shell element that calculates both the membrane and bending behavior via displacement degrees of freedom for a triangular element. The thickness stretch is statically condensed to enforce vessel wall incompressibility via a plane stress condition. Consequently, the formulation allows incorporation of appropriate 3D constitutive material models. We also incorporate external tissue support conditions to model the effect of surrounding tissue. We present theoretical and variational details of the formulation and verify our implementation against axisymmetric results and literature data. We also adapt a previously reported prestress methodology to identify the unloaded configuration corresponding to the medically imaged in vivo vessel geometry. We verify the prestress methodology in an idealized bifurcation model and demonstrate the significance of including prestress. Lastly, we demonstrate the robustness of our formulation via its application to mouse-specific models of arterial mechanics using an experimentally informed four-fiber constitutive model.
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Affiliation(s)
- Nitesh Nama
- grid.214458.e0000000086837370Department of Surgery, University of Michigan, Ann Arbor, MI USA
| | - Miquel Aguirre
- grid.6279.a0000 0001 2158 1682Mines Saint-Étienne, Univ Lyon, Univ Jean Monnet, INSERM, U 1059 Sainbiose, Centre CIS, 42023 Saint-Étienne, France
| | - Jay D. Humphrey
- grid.47100.320000000419368710Department of Biomedical Engineering, Yale University, New Haven, CT USA
| | - C. Alberto Figueroa
- grid.214458.e0000000086837370Department of Surgery, University of Michigan, Ann Arbor, MI USA ,grid.214458.e0000000086837370Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI USA
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19
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Abstract
Vascular tortuosity may impede blood flow, occlude the lumen, and ultimately lead to ischemia or even infarction. Mechanical loads like blood pressure, axial force, and also torsion are key factors participating in this complex mechanobiological process. The available studies on arterial torsion instability followed computational or experimental approaches, yet single available theoretical study had modeled the artery as isotropic linear elastic. This paper aim is to validate a theoretical model of arterial torsion instability against experimental data. The artery is modeled as a single-layered, nonlinear, hyperelastic, anisotropic solid, with parameters calibrated from experiment. Linear bifurcation analysis is then performed to predict experimentally measured stability margins. Uncertainties in geometrical parameters and in measured mechanical response were considered. Also, the type of rate (incremental) boundary conditions (RBCs) impact on the results was examined (e.g., dead load, fluid pressure). The predicted critical torque and twist angle followed the experimentally measured trends. The closest prediction errors in the critical torque and twist rate were 22% and 67%, respectively. Using the different RBCs incurred differences of up to 50% difference within the model predictions. The present results suggest that the model may require further improvements. However, it offers an approach that can be used to predict allowable twist levels in surgical procedures (like anastomosis and grafting) and in the design of stents for arteries subjected to high torsion levels (like the femoropopliteal arteries). It may also be instructive in understanding biomechanical processes like arterial tortuosity, kinking, and coiling.
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Affiliation(s)
- Nir Emuna
- Faculty of Aerospace Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - David Durban
- Faculty of Aerospace Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
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20
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Theoretical Study on Pressure Damage Based on Clinical Purpura during the Laser Irradiation of Port Wine Stains with Real Complex Vessels. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9245478] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Port wine stains (PWSs) are congenital dermal vascular lesions composed of a hyperdilated vasculature. Purpura represented by local hemorrhage from water vaporization in blood during laser therapy of PWS is typically considered a clinical feedback, but with a low cure rate. In this study, light propagation and heat deposition in skin and PWSs is simulated by a tetrahedron-based Monte Carlo method fitted to curved bio-tissues. A curvature-corrected pressure damage model was established to accurately evaluate the relationship between purpura-bleeding area (rate) and laser therapy strategy for real complex vessels. Results showed that the standard deviation of Gaussian curvature of the vessel wall has negative relation with the fluence threshold of vessel rupture, but has positive relation with the effective laser fluence of vessel damage. This finding indicated the probable reason for the poor treatment of PWS, that is, considering purpura formation as a treatment end point (TEP) only leads to partial removal of vascular lesions. Instead, appropriate purpura area ratio with marked effects or rehabilitation should be adopted as TEP. The quantitative correlation between the fluence of a pulsed dye laser and the characteristics of vascular lesions can provide personalized and precise guidance for clinical treatments.
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21
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Sharzehee M, Fatemifar F, Han HC. Computational simulations of the helical buckling behavior of blood vessels. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2019; 35:e3277. [PMID: 31680465 PMCID: PMC7286361 DOI: 10.1002/cnm.3277] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 08/27/2019] [Accepted: 10/17/2019] [Indexed: 06/10/2023]
Abstract
Tortuous vessels are often observed in vivo and could hinder or even disrupt blood flow to distal organs. Besides genetic and biological factors, the in vivo mechanical loading seems to play a role in the formation of tortuous vessels, but the mechanism for formation of helical vessel shape remains unclear. Accordingly, the aim of this study was to investigate the biomechanical loads that trigger the occurrence of helical buckling in blood vessels using finite element analysis. Porcine carotid arteries were modeled as thick-walled cylindrical tubes using generalized Fung and Holzapfel-Gasser-Ogden constitutive models. Physiological loadings, including axial tension, lumen pressure, and axial torque, were applied. Simulations of various geometric dimensions, different constitutive models and at various levels of axial stretch ratios, lumen pressures, and twist angles were performed to identify the mechanical factors that determine the helical stability. Our results demonstrated that axial torsion can cause wringing (twist buckling) that leads to kinking or helical coiling and even looping and winding. The specific buckling patterns depend on the combination of lumen pressure, axial torque, axial tension, and the dimensions of the vessels. This study elucidates the mechanism of how blood vessels buckle under various mechanical loads and how complex mechanical loads yield helical buckling.
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Affiliation(s)
- Mohammadali Sharzehee
- Department of Mechanical Engineering, The University of Texas at San Antonio, San Antonio, TX, USA
| | - Fatemeh Fatemifar
- Department of Mechanical Engineering, The University of Texas at San Antonio, San Antonio, TX, USA
| | - Hai-Chao Han
- Department of Mechanical Engineering, The University of Texas at San Antonio, San Antonio, TX, USA
- Biomedical Engineering Program, UTSA-UTHSCSA, San Antonio, TX
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22
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Sedal A, Wineman A, Gillespie RB, Remy CD. Comparison and experimental validation of predictive models for soft, fiber-reinforced actuators. Int J Rob Res 2019. [DOI: 10.1177/0278364919879493] [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]
Abstract
Successful soft robot modeling approaches appearing in the recent literature have been based on a variety of distinct theories, including traditional robotic theory, continuum mechanics, and machine learning. Though specific modeling techniques have been developed for and validated against already realized systems, their strengths and weaknesses have not been explicitly compared against each other. In this article, we show how three distinct model structures, a lumped-parameter model, a continuum mechanical model, and a neural network, compare in capturing the gross trends and specific features of the force generation of soft robotic actuators. In particular, we study models for fiber-reinforced elastomeric enclosures (FREEs), which are a popular choice of soft actuator and that are used in several soft articulated systems, including soft manipulators, exoskeletons, grippers, and locomoting soft robots. We generated benchmark data by testing eight FREE samples that spanned broad design and kinematic spaces and compared the models on their ability to predict the loading–deformation relationships of these samples. This comparison shows the predictive capabilities of each model on individual actuators and each model’s generalizability across the design space. While the neural net achieved the highest peak performance, the first principles-based models generalized best across all actuator design parameters tested. The results highlight the essential roles of mathematical structure and experimental parameter determination in building high-performing, generalizable soft actuator models with varying effort invested in system identification.
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Affiliation(s)
- Audrey Sedal
- Department of Mechanical Engineering, University of Michigan–Ann Arbor, Ann Arbor, MI, USA
| | - Alan Wineman
- Department of Mechanical Engineering, University of Michigan–Ann Arbor, Ann Arbor, MI, USA
| | - R. Brent Gillespie
- Department of Mechanical Engineering, University of Michigan–Ann Arbor, Ann Arbor, MI, USA
| | - C. David Remy
- Department of Mechanical Engineering, University of Michigan–Ann Arbor, Ann Arbor, MI, USA
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Kirkegaard JB, Nielsen BF, Trusina A, Sneppen K. Self-assembly, buckling and density-invariant growth of three-dimensional vascular networks. J R Soc Interface 2019; 16:20190517. [PMID: 31640503 PMCID: PMC6833333 DOI: 10.1098/rsif.2019.0517] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 10/02/2019] [Indexed: 12/19/2022] Open
Abstract
The experimental actualization of organoids modelling organs from brains to pancreases has revealed that much of the diverse morphologies of organs are emergent properties of simple intercellular 'rules' and not the result of top-down orchestration. In contrast to other organs, the initial plexus of the vascular system is formed by aggregation of cells in the process known as vasculogenesis. Here we study this self-assembling process of blood vessels in three dimensions through a set of simple rules that align intercellular apical-basal and planar cell polarity. We demonstrate that a fully connected network of tubes emerges above a critical initial density of cells. Through planar cell polarity, our model demonstrates convergent extension, and this polarity furthermore allows for both morphology-maintaining growth and growth-induced buckling. We compare this buckling with the special vasculature of the islets of Langerhans in the pancreas and suggest that the mechanism behind the vascular density-maintaining growth of these islets could be the result of growth-induced buckling.
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24
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Morley CD, Ellison ST, Bhattacharjee T, O'Bryan CS, Zhang Y, Smith KF, Kabb CP, Sebastian M, Moore GL, Schulze KD, Niemi S, Sawyer WG, Tran DD, Mitchell DA, Sumerlin BS, Flores CT, Angelini TE. Quantitative characterization of 3D bioprinted structural elements under cell generated forces. Nat Commun 2019; 10:3029. [PMID: 31292444 PMCID: PMC6620298 DOI: 10.1038/s41467-019-10919-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 06/03/2019] [Indexed: 12/31/2022] Open
Abstract
With improving biofabrication technology, 3D bioprinted constructs increasingly resemble real tissues. However, the fundamental principles describing how cell-generated forces within these constructs drive deformations, mechanical instabilities, and structural failures have not been established, even for basic biofabricated building blocks. Here we investigate mechanical behaviours of 3D printed microbeams made from living cells and extracellular matrix, bioprinting these simple structural elements into a 3D culture medium made from packed microgels, creating a mechanically controlled environment that allows the beams to evolve under cell-generated forces. By varying the properties of the beams and the surrounding microgel medium, we explore the mechanical behaviours exhibited by these structures. We observe buckling, axial contraction, failure, and total static stability, and we develop mechanical models of cell-ECM microbeam mechanics. We envision these models and their generalizations to other fundamental 3D shapes to facilitate the predictable design of biofabricated structures using simple building blocks in the future.
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Affiliation(s)
- Cameron D Morley
- University of Florida, Herbert Wertheim College of Engineering, Department of Mechanical and Aerospace Engineering, Gainesville, FL, 32611, USA
| | - S Tori Ellison
- University of Florida, Herbert Wertheim College of Engineering, Department of Materials Science and Engineering, Gainesville, FL, 32611, USA
| | - Tapomoy Bhattacharjee
- Princeton University, Department of Chemical and Biological Engineering, Princeton, NJ, 08540, USA
| | - Christopher S O'Bryan
- University of Florida, Herbert Wertheim College of Engineering, Department of Mechanical and Aerospace Engineering, Gainesville, FL, 32611, USA
| | - Yifan Zhang
- University of Florida, Herbert Wertheim College of Engineering, Department of Mechanical and Aerospace Engineering, Gainesville, FL, 32611, USA
| | - Kourtney F Smith
- University of Florida, Herbert Wertheim College of Engineering, Department of Materials Science and Engineering, Gainesville, FL, 32611, USA
| | - Christopher P Kabb
- University of Florida, George and Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science and Engineering, Department of Chemistry, Gainesville, FL, 32611, USA
| | - Mathew Sebastian
- Division of Neuro-Oncology, Preston A. Wells, Jr. Center for Brain Tumor Therapy, Lillian S. Wells Department of Neurosurgery, University of Florida, Gainesville, FL, 32611, USA
| | - Ginger L Moore
- University of Florida, Brain Tumor Immunotherapy Program, Preston A. Wells Jr. Center for Brain Tumor Therapy, Lillian S. Wells Department of Neurosurgery, Gainesville, FL, 32611, USA
| | - Kyle D Schulze
- Auburn University, Department of Mechanical Engineering, Auburn, AL, 36849, USA
| | - Sean Niemi
- University of Florida, Herbert Wertheim College of Engineering, Department of Mechanical and Aerospace Engineering, Gainesville, FL, 32611, USA
| | - W Gregory Sawyer
- University of Florida, Herbert Wertheim College of Engineering, Department of Mechanical and Aerospace Engineering, Gainesville, FL, 32611, USA
- University of Florida, Herbert Wertheim College of Engineering, Department of Materials Science and Engineering, Gainesville, FL, 32611, USA
| | - David D Tran
- Division of Neuro-Oncology, Preston A. Wells, Jr. Center for Brain Tumor Therapy, Lillian S. Wells Department of Neurosurgery, University of Florida, Gainesville, FL, 32611, USA
| | - Duane A Mitchell
- University of Florida, Brain Tumor Immunotherapy Program, Preston A. Wells Jr. Center for Brain Tumor Therapy, Lillian S. Wells Department of Neurosurgery, Gainesville, FL, 32611, USA
| | - Brent S Sumerlin
- University of Florida, George and Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science and Engineering, Department of Chemistry, Gainesville, FL, 32611, USA
| | - Catherine T Flores
- University of Florida, Brain Tumor Immunotherapy Program, Preston A. Wells Jr. Center for Brain Tumor Therapy, Lillian S. Wells Department of Neurosurgery, Gainesville, FL, 32611, USA
| | - Thomas E Angelini
- University of Florida, Herbert Wertheim College of Engineering, Department of Mechanical and Aerospace Engineering, Gainesville, FL, 32611, USA.
- University of Florida, Herbert Wertheim College of Engineering, Department of Materials Science and Engineering, Gainesville, FL, 32611, USA.
- University of Florida, Herbert Wertheim College of Engineering, J. Crayton Pruitt Family Department of Biomedical Engineering, Gainesville, FL, 32611, USA.
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25
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Hassan AK, Abd–El Rahman H, Hassan SG, Ahmed TA, Youssef AAA. Validity of tortuosity severity index in chest pain patients with abnormal exercise test and normal coronary angiography. Egypt Heart J 2018; 70:381-387. [PMID: 30591760 PMCID: PMC6303525 DOI: 10.1016/j.ehj.2018.07.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Accepted: 07/14/2018] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Coronary tortuosity (CT) had different definitions and scores in literature with unclear pathophysiological impact. OBJECTIVES To study degree of CT and it's relation to ischemic changes in patients with angina but normal coronary angiography (CA). METHODS We conducted a prospective study at University hospitals between May 2016 and January 2017. We included 200 consecutive patients who underwent CA due to chest pain assumed to be of cardiac origin, and their CA was normal (no diameter stenosis >30%, nor myocardial bridging). Patients were prospectively divided into 2 groups based on the presence (n = 113) or absence (n = 87) of ischemic changes during stress study and compared for clinical, echocardiographic and CA characteristics. A newly proposed Tortuosity Severity Index (TSI) was developed into significant (mild/moderate CT with more than 4 curvatures in total, or severe/extreme CT with any number of curvatures) or not significant TSI (mild CT with curvatures less than or equal to 4 curvatures in total). RESULTS Patients with ischemic changes had the highest rate of CT (76.5 vs 18%, p = 0.004) compared to those without. CT mostly affects the left anterior descending (LAD) coronary artery in mid and distal segments. Females, elderly, and hypertensives with left ventricular hypertrophy were strongly related to CT. Multivariate logistic regression analysis identified CT with significant TSI as the only predictor of ischemic changes in these patients (OR = 6.2, CI = 2.5-15.3, P = <0.001). CONCLUSIONS Coronary tortuosity is a strong predictor of anginal pain among patients with normal CA, despite positive stress study. This finding is more pronounced among elderly, hypertensive female patients.
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Affiliation(s)
- Ayman K.M. Hassan
- Department of Cardiology, Faculty of Medicine, Assiut University, Egypt
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26
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Abstract
The stability of the arteries under in vivo pressure and axial tension loads is essential to normal arterial function, and lumen collapse due to buckling can hinder the blood flow. The objective of this study was to develop the lumen buckling equation for nonlinear anisotropic thick-walled arteries to determine the effect of axial tension. The theoretical equation was developed using exponential Fung strain function, and the effects of axial tension and residual stress on the critical buckling pressure were illustrated for porcine coronary arteries. The buckling behavior was also simulated using finite-element analysis. Our results demonstrated that lumen collapse of arteries could occur when the transmural pressure is negative and exceeded a critical value. This value depends upon the axial stretch ratio and material properties of the arterial wall. Axial tensions show a biphasic effect on the critical buckling pressure. The lumen aspect ratio of arteries increases nonlinearly with increasing external pressure beyond the critical value as the lumen collapses. These results enhance our understanding of artery lumen collapse behavior.
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27
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Tubaldi E, Païdoussis MP, Amabili M. Nonlinear Dynamics of Dacron Aortic Prostheses Conveying Pulsatile Flow. J Biomech Eng 2018; 140:2672765. [DOI: 10.1115/1.4039284] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Indexed: 11/08/2022]
Abstract
This study addresses the dynamic response to pulsatile physiological blood flow and pressure of a woven Dacron graft currently used in thoracic aortic surgery. The model of the prosthesis assumes a cylindrical orthotropic shell described by means of nonlinear Novozhilov shell theory. The blood flow is modeled as Newtonian pulsatile flow, and unsteady viscous effects are included. Coupled fluid–structure Lagrange equations for open systems with wave propagation subject to pulsatile flow are applied. Physiological waveforms of blood pressure and velocity are approximated with the first eight harmonics of the corresponding Fourier series. Time responses of the prosthetic wall radial displacement are considered for two physiological conditions: at rest (60 bpm) and at high heart rate (180 bpm). While the response at 60 bpm reproduces the behavior of the pulsatile pressure, higher harmonics frequency contributions are observed at 180 bpm altering the shape of the time response. Frequency-responses show resonance peaks for heart rates between 130 bpm and 200 bpm due to higher harmonics of the pulsatile flow excitation. These resonant peaks correspond to unwanted high-frequency radial oscillations of the vessel wall that can compromise the long-term functioning of the prosthesis in case of significant physical activity. Thanks to this study, the dynamic response of Dacron prostheses to pulsatile flow can be understood as well as some possible complications in case of significant physical activity.
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Affiliation(s)
- Eleonora Tubaldi
- Mem. ASME Department of Mechanical Engineering, McGill University, Macdonald Engineering Building, 817 Sherbrooke Street West, Montreal, QC H3A 0C3, Canada e-mail:
| | - Michael P. Païdoussis
- Professor Fellow ASME Department of Mechanical Engineering, McGill University, Macdonald Engineering Building, 817 Sherbrooke Street West, Montreal, QC H3A 0C3, Canada e-mail:
| | - Marco Amabili
- Professor Fellow ASME Department of Mechanical Engineering, McGill University, Macdonald Engineering Building, 817 Sherbrooke Street West, Montreal, QC H3A 0C3 Canada e-mail:
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28
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Sharzehee M, Khalafvand SS, Han HC. Fluid-structure interaction modeling of aneurysmal arteries under steady-state and pulsatile blood flow: a stability analysis. Comput Methods Biomech Biomed Engin 2018; 21:219-231. [PMID: 29446991 PMCID: PMC5879495 DOI: 10.1080/10255842.2018.1439478] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Tortuous aneurysmal arteries are often associated with a higher risk of
rupture but the mechanism remains unclear. The goal of this study was to analyze
the buckling and post-buckling behaviors of aneurysmal arteries under pulsatile
flow. To accomplish this goal, we analyzed the buckling behavior of model
carotid and abdominal aorta with aneurysms by utilizing fluid-structure
interaction (FSI) method with realistic waveforms boundary conditions. FSI
simulations were done under steady-state and pulsatile flow for normal (1.5) and
reduced (1.3) axial stretch ratios to investigate the influence of aneurysm,
pulsatile lumen pressure and axial tension on stability. Our results indicated
that aneurysmal artery buckled at the critical buckling pressure and its
deflection nonlinearly increased with increasing lumen pressure. Buckling
elevates the peak stress (up to 118%). The maximum aneurysm wall stress
at pulsatile FSI flow was (29%) higher than under static pressure at the
peak lumen pressure of 130 mmHg. Buckling results show an increase in lumen
shear stress at the inner side of the maximum deflection. Vortex flow was
dramatically enlarged with increasing lumen pressure and artery diameter.
Aneurysmal arteries are more susceptible than normal arteries to mechanical
instability which causes high stresses in the aneurysm wall that could lead to
aneurysm rupture.
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Affiliation(s)
- Mohammadali Sharzehee
- a Department of Mechanical Engineering , The University of Texas at San Antonio , San Antonio , TX , USA
| | | | - Hai-Chao Han
- a Department of Mechanical Engineering , The University of Texas at San Antonio , San Antonio , TX , USA
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29
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Dacron graft as replacement to dissected aorta: A three-dimensional fluid-structure-interaction analysis. J Mech Behav Biomed Mater 2018; 78:329-341. [DOI: 10.1016/j.jmbbm.2017.11.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 11/20/2017] [Indexed: 11/21/2022]
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30
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SHEN XIANG, DENG YONGQUAN, JI SONG, XIE ZHONGMIN, ZHU HONGFEI. FLEXIBILITY BEHAVIOR OF CORONARY STENTS: THE ROLE OF LINKER INVESTIGATED WITH NUMERICAL SIMULATION. J MECH MED BIOL 2018. [DOI: 10.1142/s0219519417501123] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Flexibility is a vital property of stents and different stent structures lead to different flexibility behaviors. In this study, the finite element analysis was adopted and a virtual bending deformation was imposed to quantify the effects of linker pattern, linker number, bending direction and linker location on flexibility. Stent performance indicators, including stress distribution, deformation patterns and bending stiffness, were examined. Results indicate that higher levels of stresses are found on the linker struts, associated with much larger deformation. The linker number plays the most significant role in flexibility, and simply decreasing linker number could result in a sharp increase in flexibility and a decrease in stress. The linker pattern has great impact on stent flexibility, especially on the behavior of self-contact. Stents with different linker patterns could respond differently in the course of bending, and the stent with an offset peak-to-peak linker pattern is the best choice. It is also found that stent flexibility can be improved when fewer linkers lie in the compression area and the linker directions between two adjacent rows are consistent. The results obtained could provide useful information for the improvement of stent design and clinical choice.
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Affiliation(s)
- XIANG SHEN
- School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, P. R. China
| | - YONG-QUAN DENG
- School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, P. R. China
| | - SONG JI
- School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, P. R. China
| | - ZHONG-MIN XIE
- School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, P. R. China
| | - HONG-FEI ZHU
- School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, P. R. China
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31
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Kinematics of collagen fibers in carotid arteries under tension-inflation loading. J Mech Behav Biomed Mater 2018; 77:718-726. [DOI: 10.1016/j.jmbbm.2017.08.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 08/07/2017] [Accepted: 08/09/2017] [Indexed: 01/15/2023]
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32
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Kinking and Torsion Can Significantly Improve the Efficiency of Valveless Pumping in Periodically Compressed Tubular Conduits. Implications for Understanding of the Form-Function Relationship of Embryonic Heart Tubes. J Cardiovasc Dev Dis 2017; 4:jcdd4040019. [PMID: 29367548 PMCID: PMC5753120 DOI: 10.3390/jcdd4040019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 11/14/2017] [Accepted: 11/15/2017] [Indexed: 01/01/2023] Open
Abstract
Valveless pumping phenomena (peristalsis, Liebau-effect) can generate unidirectional fluid flow in periodically compressed tubular conduits. Early embryonic hearts are tubular conduits acting as valveless pumps. It is unclear whether such hearts work as peristaltic or Liebau-effect pumps. During the initial phase of its pumping activity, the originally straight embryonic heart is subjected to deforming forces that produce bending, twisting, kinking, and coiling. This deformation process is called cardiac looping. Its function is traditionally seen as generating a configuration needed for establishment of correct alignments of pulmonary and systemic flow pathways in the mature heart of lung-breathing vertebrates. This idea conflicts with the fact that cardiac looping occurs in all vertebrates, including gill-breathing fishes. We speculate that looping morphogenesis may improve the efficiency of valveless pumping. To test the physical plausibility of this hypothesis, we analyzed the pumping performance of a Liebau-effect pump in straight and looped (kinked) configurations. Compared to the straight configuration, the looped configuration significantly improved the pumping performance of our pump. This shows that looping can improve the efficiency of valveless pumping driven by the Liebau-effect. Further studies are needed to clarify whether this finding may have implications for understanding of the form-function relationship of embryonic hearts.
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Haemodynamic Recovery Properties of the Torsioned Testicular Artery Lumen. Sci Rep 2017; 7:15570. [PMID: 29138449 PMCID: PMC5686114 DOI: 10.1038/s41598-017-15680-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 10/31/2017] [Indexed: 11/08/2022] Open
Abstract
Testicular artery torsion (twisting) is one such severe vascular condition that leads spermatic cord injury. In this study, we investigate the recovery response of a torsioned ram testicular artery in an isolated organ-culture flow loop with clinically relevant twisting modes (90°, 180°, 270° and 360° angles). Quantitative optical coherence tomography technique was employed to track changes in the lumen diameter, wall thickness and the three-dimensional shape of the vessel in the physiological pressure range (10-50 mmHg). As a control, pressure-flow characteristics of the untwisted arteries were studied when subjected to augmented blood flow conditions with physiological flow rates up to 36 ml/min. Both twist and C-shaped buckling modes were observed. Acute increase in pressure levels opened the narrowed lumen of the twisted arteries noninvasively at all twist angles (at ∼22 mmHg and ∼35 mmHg for 360°-twisted vessels during static and dynamic flow experiments, respectively). The association between the twist-opening flow rate and the vessel diameter was greatly influenced by the initial twist angle. The biomechanical characteristics of the normal (untwisted) and torsioned testicular arteries supported the utilization of blood flow augmentation as an effective therapeutic approach to modulate the vessel lumen and recover organ reperfusion.
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34
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Arterial wall remodeling under sustained axial twisting in rats. J Biomech 2017; 60:124-133. [PMID: 28693818 DOI: 10.1016/j.jbiomech.2017.06.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 06/13/2017] [Accepted: 06/14/2017] [Indexed: 01/03/2023]
Abstract
Blood vessels often experience torsion along their axes and it is essential to understand their biological responses and wall remodeling under torsion. To this end, a rat model was developed to investigate the arterial wall remodeling under sustained axial twisting in vivo. Rat carotid arteries were twisted at 180° along the longitudinal axis through a surgical procedure and maintained for different durations up to 4weeks. The wall remodeling in these twisted arteries was examined using histology, immunohistochemistry and fluorescent microscopy. Our data showed that arteries remodeled under twisting in a time-dependent manner during the 4weeks post-surgery. Cell proliferation, MMP-2 and MMP-9 expressions, medial wall thickness and lumen diameter increased while collagen to elastin ratio decreased. The size and number of internal elastic lamina fenestrae increased with elongated shapes, while the endothelial cells elongated and aligned towards the blood flow direction gradually. These results demonstrated that sustained axial twisting results in artery remodeling in vivo. The rat carotid artery twisting model is an effective in vivo model for studying arterial wall remodeling under long-term torsion. These results enrich our understanding of vascular biology and arterial wall remodeling under mechanical stresses.
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35
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Garcia JR, Sanyal A, Fatemifar F, Mottahedi M, Han HC. Twist buckling of veins under torsional loading. J Biomech 2017; 58:123-130. [PMID: 28526174 DOI: 10.1016/j.jbiomech.2017.04.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 03/31/2017] [Accepted: 04/24/2017] [Indexed: 10/19/2022]
Abstract
Veins are often subjected to torsion and twisted veins can hinder and disrupt normal blood flow but their mechanical behavior under torsion is poorly understood. The objective of this study was to investigate the twist deformation and buckling behavior of veins under torsion. Twist buckling tests were performed on porcine internal jugular veins (IJVs) and human great saphenous veins (GSVs) at various axial stretch ratio and lumen pressure conditions to determine their critical buckling torques and critical buckling twist angles. The mechanical behavior under torsion was characterized using a two-fiber strain energy density function and the buckling behavior was then simulated using finite element analysis. Our results demonstrated that twist buckling occurred in all veins under excessive torque characterized by a sudden kink formation. The critical buckling torque increased significantly with increasing lumen pressure for both porcine IJV and human GSV. But lumen pressure and axial stretch had little effect on the critical twist angle. The human GSVs are stiffer than the porcine IJVs. Finite element simulations captured the buckling behavior for individual veins under simultaneous extension, inflation, and torsion with strong correlation between predicted critical buckling torques and experimental data (R2=0.96). We conclude that veins can buckle under torsion loading and the lumen pressure significantly affects the critical buckling torque. These results improve our understanding of vein twist behavior and help identify key factors associated in the formation of twisted veins.
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Affiliation(s)
- Justin R Garcia
- Department of Mechanical Engineering, University of Texas at San Antonio, USA; Biomedical Engineering Program, UTSA-UTHSCSA, USA
| | - Arnav Sanyal
- Department of Mechanical Engineering, University of Texas at San Antonio, USA
| | - Fatemeh Fatemifar
- Department of Mechanical Engineering, University of Texas at San Antonio, USA
| | - Mohammad Mottahedi
- Department of Mechanical Engineering, University of Texas at San Antonio, USA
| | - Hai-Chao Han
- Department of Mechanical Engineering, University of Texas at San Antonio, USA; Biomedical Engineering Program, UTSA-UTHSCSA, USA; Institute of Mechanobiology & Medical Engineering, Shanghai Jiaotong University, China.
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36
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Zilberman-Rudenko J, Sylman JL, Garland KS, Puy C, Wong AD, Searson PC, McCarty OJT. Utility of microfluidic devices to study the platelet-endothelium interface. Platelets 2017; 28:449-456. [PMID: 28358586 DOI: 10.1080/09537104.2017.1280600] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The integration of biomaterials and understanding of vascular biology has led to the development of perfusable endothelialized flow models, which have been used as valuable tools to study the platelet-endothelium interface under shear. In these models, the parameters of geometry, compliance, biorheology, and cellular complexity are varied to recapitulate the physical biology of platelet recruitment and activation under physiologically relevant conditions of blood flow. In this review, we summarize the mechanistic insights learned from perfusable microvessel models and discuss the potential utility as well as challenges of endothelialized microfluidic devices to study platelet function in the bloodstream in vitro.
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Affiliation(s)
- Jevgenia Zilberman-Rudenko
- a Biomedical Engineering, School of Medicine , Oregon Health and Science University , Portland , OR , USA
| | - Joanna L Sylman
- a Biomedical Engineering, School of Medicine , Oregon Health and Science University , Portland , OR , USA
| | - Kathleen S Garland
- a Biomedical Engineering, School of Medicine , Oregon Health and Science University , Portland , OR , USA.,c Division of Pediatric Hematology/Oncology , Oregon Health and Science University , Portland , OR , USA
| | - Cristina Puy
- a Biomedical Engineering, School of Medicine , Oregon Health and Science University , Portland , OR , USA
| | - Andrew D Wong
- b Institute for Nanobiotechnology (INBT) , Johns Hopkins University , Baltimore , MD , USA.,d Department of Materials Science and Engineering , Johns Hopkins University , Baltimore , MD , USA
| | - Peter C Searson
- b Institute for Nanobiotechnology (INBT) , Johns Hopkins University , Baltimore , MD , USA.,d Department of Materials Science and Engineering , Johns Hopkins University , Baltimore , MD , USA
| | - Owen J T McCarty
- a Biomedical Engineering, School of Medicine , Oregon Health and Science University , Portland , OR , USA.,c Division of Pediatric Hematology/Oncology , Oregon Health and Science University , Portland , OR , USA
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37
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Gavish B, Izzo JL. Arterial Stiffness: Going a Step Beyond. Am J Hypertens 2016; 29:1223-1233. [PMID: 27405964 DOI: 10.1093/ajh/hpw061] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 05/23/2016] [Indexed: 01/09/2023] Open
Abstract
Interest in arterial stiffness has been fueled by the scientific and clinical implications of its "vicious cycle" relationship with aging and systolic blood pressure. In physical terms, stiffness is the slope of the relationship between an artery's distending pressure and its cross-sectional area or volume. Pulse wave velocity (PWV, in m/s), the most common arterial stiffness indicator, is usually measured by the foot-to-foot time and distance method and is proportional to [stiffness × area (or volume)]1/2 at a given pressure. Its intrinsic pressure dependency and other flaws in current PWV methods limit its utility. In contrast, the arterial stiffness-arterial pressure relationship is near-linear, with a slope β, the exponent of the curvilinear arterial pressure-arterial volume relationship. The concept of arterial stiffening is related to β and describes a more functionally relevant aspect of arterial behavior: the change in stiffness for a given change in pressure. Arterial stiffening can be estimated from the variability of within-individual BP measurements (24-h ambulatory, home BP, or BP measured at different arm heights) and can be expressed as the pulse stiffening ratio (PSR) = [systolic stiffness]/[diastolic stiffness] or the ambulatory arterial stiffness index (AASI or its symmetric form, sAASI). High arterial stiffness (PWV) and stiffening (β, stiffness index, cardio-ankle vascular index, AASI, and PSR) are associated with increased cardiovascular disease risk, but it remains unclear whether these indicators are useful in improving medical care quality; the standard of care remains stringent BP control.
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Affiliation(s)
- Benjamin Gavish
- Department of Medicine, University at Buffalo, Buffalo, New York, USA
| | - Joseph L Izzo
- Department of Medicine, University at Buffalo, Buffalo, New York, USA
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38
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Han HC, Liu Q, Jiang ZL. Mechanical behavior and wall remodeling of blood vessels under axial twist. YI YONG SHENG WU LI XUE 2016; 31:319-326. [PMID: 28529430 PMCID: PMC5437748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Blood vessels are often subjected to axial torsion (or twist) due to body movement or surgery. However, there are few studies on blood vessel under twist. This review first summarizes the clinical observation on the twist of blood vessels and then presents what we know about the mechanical behaviors of blood vessel under twist, including the constitutive models. The state of art researches on the remodeling of blood vessels under twist via ex vivo organ culture, in vivo animal experiments, and mathematical model simulations are further discussed. It is our hope that this review will draw attention for further in-depth studies on the behavior and remodeling of blood vessels under twist.
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Affiliation(s)
- Hai-Chao Han
- Department of Mechanical Engineering, University of Texas at San Antonio, San Antonio, TX 78249, USA
- Institute of Mechanobiology & Medical Engineering, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Qin Liu
- Department of Mechanical Engineering, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Zong-Lai Jiang
- Institute of Mechanobiology & Medical Engineering, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
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Artery buckling analysis using a two-layered wall model with collagen dispersion. J Mech Behav Biomed Mater 2016; 60:515-524. [PMID: 27031686 DOI: 10.1016/j.jmbbm.2016.03.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 02/24/2016] [Accepted: 03/09/2016] [Indexed: 01/23/2023]
Abstract
Artery buckling has been proposed as a possible cause for artery tortuosity associated with various vascular diseases. Since microstructure of arterial wall changes with aging and diseases, it is essential to establish the relationship between microscopic wall structure and artery buckling behavior. The objective of this study was to developed arterial buckling equations to incorporate the two-layered wall structure with dispersed collagen fiber distribution. Seven porcine carotid arteries were tested for buckling to determine their critical buckling pressures at different axial stretch ratios. The mechanical properties of these intact arteries and their intima-media layer were determined via pressurized inflation test. Collagen alignment was measured from histological sections and modeled by a modified von-Mises distribution. Buckling equations were developed accordingly using microstructure-motivated strain energy function. Our results demonstrated that collagen fibers disperse around two mean orientations symmetrically to the circumferential direction (39.02°±3.04°) in the adventitia layer; while aligning closely in the circumferential direction (2.06°±3.88°) in the media layer. The microstructure based two-layered model with collagen fiber dispersion described the buckling behavior of arteries well with the model predicted critical pressures match well with the experimental measurement. Parametric studies showed that with increasing fiber dispersion parameter, the predicted critical buckling pressure increases. These results validate the microstructure-based model equations for artery buckling and set a base for further studies to predict the stability of arteries due to microstructural changes associated with vascular diseases and aging.
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Kamenskiy A, Seas A, Bowen G, Deegan P, Desyatova A, Bohlim N, Poulson W, MacTaggart J. In situ longitudinal pre-stretch in the human femoropopliteal artery. Acta Biomater 2016; 32:231-237. [PMID: 26766633 DOI: 10.1016/j.actbio.2016.01.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 12/21/2015] [Accepted: 01/04/2016] [Indexed: 11/30/2022]
Abstract
In situ longitudinal (axial) pre-stretch (LPS) plays a fundamental role in the mechanics of the femoropopliteal artery (FPA). It conserves energy during pulsation and prevents buckling of the artery during limb movement. We investigated how LPS is affected by demographics and risk factors, and how these patient characteristics associate with the structural and physiologic features of the FPA. LPS was measured in n=148 fresh human FPAs (14-80 years old). Mechanical properties were characterized with biaxial extension and histopathological characteristics were quantified with Verhoeff-Van Gieson Staining. Constitutive modeling was used to calculate physiological stresses and stretches which were then analyzed in the context of demographics, risk factors and structural characteristics. Age had the strongest negative effect (r=-0.812, p<0.01) on LPS and could alone explain 66% of LPS variability. Male gender, higher body mass index, hypertension, diabetes, coronary artery disease, dyslipidemia and tobacco use had negative effects on LPS, but only the effect of tobacco was not associated with aging. FPAs with less pre-stretch had thicker medial layers, but thinner intramural elastic fibers with less dense and more fragmented external elastic laminae. Elastin degradation was associated with decreased physiological tethering force and longitudinal stress, while circumferential stress remained constant. FPA wall pathology was negatively associated with LPS (r=-0.553, p<0.01), but the effect was due primarily to aging. LPS in the FPA may serve as an energy reserve for adaptive remodeling. Reduction of LPS due to degradation and fragmentation of intramural longitudinal elastin during aging can be accelerated in tobacco users. STATEMENT OF SIGNIFICANCE This work studies in situ longitudinal pre-stretch (LPS) in the human femoropopliteal artery. LPS has a fundamental role in arterial mechanics, but is rather poorly studied due to lack of direct in vivo measurement method. We have investigated LPS in the n=148 human femoropopliteal arteries in the context of subject demographics and risk factors, and structural and physiologic characteristics of the artery. Our results demonstrate that LPS reduces with age due to degradation and fragmentation of intramural elastin. LPS may serve as an energy reserve for adaptive remodeling, and reduction of LPS can be accelerated in tobacco users.
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Affiliation(s)
- Alexey Kamenskiy
- Dept of Surgery, University of Nebraska Medical Center, Omaha, NE, United States.
| | - Andreas Seas
- Dept of Chemical Engineering, University of Maryland, Baltimore County, MD, United States
| | - Grant Bowen
- Dept of Surgery, University of Nebraska Medical Center, Omaha, NE, United States
| | - Paul Deegan
- Dept of Surgery, University of Nebraska Medical Center, Omaha, NE, United States
| | - Anastasia Desyatova
- Dept of Surgery, University of Nebraska Medical Center, Omaha, NE, United States; Dept of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE, United States
| | - Nick Bohlim
- Dept of Surgery, University of Nebraska Medical Center, Omaha, NE, United States
| | - William Poulson
- Dept of Surgery, University of Nebraska Medical Center, Omaha, NE, United States
| | - Jason MacTaggart
- Dept of Surgery, University of Nebraska Medical Center, Omaha, NE, United States.
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Buckling Reduces eNOS Production and Stimulates Extracellular Matrix Remodeling in Arteries in Organ Culture. Ann Biomed Eng 2016; 44:2840-50. [PMID: 26913855 DOI: 10.1007/s10439-016-1571-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 02/17/2016] [Indexed: 12/26/2022]
Abstract
Artery buckling alters the fluid shear stress and wall stress in the artery but its temporal effect on vascular wall remodeling is poorly understood. The purpose of this study was to investigate the early effect of artery buckling on endothelial nitric oxide synthase (eNOS) expression and extracellular matrix remodeling. Bilateral porcine carotid arteries were maintained in an ex vivo organ culture system with and without buckling while under the same physiological pressure and flow rate for 3-7 days. Matrix metalloproteinase-2 (MMP-2), MMP-9, fibronectin, elastin, collagen I, III and IV, tissue inhibitor of metalloproteinase-2 (TIMP-2), and eNOS were determined using Western blotting and immunohistochemistry. Our results showed that MMP-2 expression level was significantly higher in buckled arteries than in the controls and higher at the inner curve than at the outer curve of buckled arteries, while collagen IV content showed an opposite trend, suggesting that artery buckling increased MMP-2 expression and collagen IV degradation in a site-specific fashion. However, no differences for MMP-9, fibronectin, elastin, collagen I, III, and TIMP-2 were observed among the outer and inner curve sides of buckled arteries and straight controls. Additionally, eNOS expression was significantly decreased in buckled arteries. These results suggest that artery buckling triggers uneven wall remodeling that could lead to development of tortuous arteries.
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An in Vitro Twist Fatigue Test of Fabric Stent-Grafts Supported by Z-Stents vs. Ringed Stents. MATERIALS 2016; 9:ma9020113. [PMID: 28787913 PMCID: PMC5456472 DOI: 10.3390/ma9020113] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Revised: 01/27/2016] [Accepted: 02/03/2016] [Indexed: 11/17/2022]
Abstract
Whereas buckling can cause type III endoleaks, long-term twisting of a stent-graft was investigated here as a mechanism leading to type V endoleak or endotension. Two experimental device designs supported with Z-stents having strut angles of 35° or 45° were compared to a ringed control under accelerated twisting. Damage to each device was assessed and compared after different durations of twisting, with focus on damage that may allow leakage. Stent-grafts with 35° Z-stents had the most severe distortion and damage to the graft fabric. The 45° Z-stents caused less fabric damage. However, consistent stretching was still seen around the holes for sutures, which attach the stents to the graft fabric. Larger holes may become channels for fluid percolation through the wall. The ringed stent-graft had the least damage observed. Stent apexes with sharp angles appear to be responsible for major damage to the fabrics. Device manufacturers should consider stent apex angle when designing stent-grafts, and ensure their devices are resistant to twisting.
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A computational study of stent performance by considering vessel anisotropy and residual stresses. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2016; 62:307-16. [PMID: 26952428 DOI: 10.1016/j.msec.2016.01.064] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 01/11/2016] [Accepted: 01/24/2016] [Indexed: 11/23/2022]
Abstract
Finite element simulations of stent deployment were carried out by considering the intrinsic anisotropic behaviour, described by a Holzapfel-Gasser-Ogden (HGO) hyperelastic anisotropic model, of individual artery layers. The model parameters were calibrated against the experimental stress-stretch responses in both circumferential and longitudinal directions. The results showed that stent expansion, system recoiling and stresses in the artery layers were greatly affected by vessel anisotropy. Following deployment, deformation of the stent was also modelled by applying relevant biomechanical forces, i.e. in-plane bending and radial compression, to the stent-artery system, for which the residual stresses generated during deployment were particularly accounted for. Residual stresses were found to have a significant influence on the deformation of the system, resulting in a re-distribution of stresses and a change of the system flexibility. The results were also utilised to interpret the mechanical performance of stent after deployment.
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Shariatpanahi SP, Etesami Z, Iraji zad A, Bonn D, Ejtehadi MR. Different buckling regimes in direct electrospinning: A comparative approach to rope buckling. ACTA ACUST UNITED AC 2015. [DOI: 10.1002/polb.23964] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- S. P. Shariatpanahi
- Institute of Biochemistry and Biophysics, University of Tehran; P.O. Box 13145-1384 Tehran Iran
| | - Z. Etesami
- Department of Physics; Sharif University of Technology; P.O. Box 11155-9161 Tehran Iran
| | - A. Iraji zad
- Department of Physics; Sharif University of Technology; P.O. Box 11155-9161 Tehran Iran
- Institute for Nanoscience and Nanotechnology (INST), Sharif University of Technology; P.O. Box 11155-9161 Tehran Iran
| | - D. Bonn
- Van Der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam; Science Park 904 Amsterdam 1098XH Netherlands
- Laboratoire De Physique Statistique, CNRS UMR 8550, École Normale Supérieure; 24 Rue Lhomond Paris Cedex 05 75231 France
| | - M. R. Ejtehadi
- Department of Physics; Sharif University of Technology; P.O. Box 11155-9161 Tehran Iran
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Xiao Y, Hayman D, Khalafvand SS, Lindsey ML, Han HC. Artery buckling stimulates cell proliferation and NF-κB signaling. Am J Physiol Heart Circ Physiol 2015; 307:H542-51. [PMID: 24929858 DOI: 10.1152/ajpheart.00079.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Tortuous carotid arteries are often seen in aged populations and are associated with atherosclerosis, but the underlying mechanisms to explain this preference are unclear. Artery buckling has been suggested as one potential mechanism for the development of tortuous arteries. The objective of this study, accordingly, was to determine the effect of buckling on cell proliferation and associated NF-κB activation in arteries. We developed a technique to generate buckling in porcine carotid arteries using long artery segments in organ culture without changing the pressure, flow rate, and axial stretch ratio. Using this technique, we examined the effect of buckling on arterial wall remodeling in 4-day organ culture under normal and hypertensive pressures. Cell proliferation, NF-κB p65, IκB-α, ERK1/2, and caspase-3 were detected using immunohistochemistry staining and immunoblot analysis. Our results showed that cell proliferation was elevated 5.8-fold in the buckling group under hypertensive pressure (n = 7, P < 0.01) with higher levels of NF-κB nuclear translocation and IκB-α degradation (P < 0.05 for both). Greater numbers of proliferating cells were observed on the inner curve side of the buckled arteries compared with the outer curve side (P < 0.01). NF-κB colocalized with proliferative nuclei. Computational simulations using a fluid-structure interaction model showed reduced wall stress on the inner side of buckled arteries and elevated wall stress on the outer side. We conclude that arterial buckling promotes site-specific wall remodeling with increased cell proliferation and NF-κB activation. These findings shed light on the biomechanical and molecular mechanisms of the pathogenesis of atherosclerosis in tortuous arteries.
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Vandiver RM. Buckling instability in arteries. J Theor Biol 2015; 371:1-8. [DOI: 10.1016/j.jtbi.2015.01.039] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Revised: 01/27/2015] [Accepted: 01/28/2015] [Indexed: 11/29/2022]
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Munger KA, Downey TM, Haberer B, Pohlson K, Marshall LL, Utecht RE. A novel photochemical cross-linking technology to improve luminal gain, vessel compliance, and buckling post-angioplasty in porcine arteries. J Biomed Mater Res B Appl Biomater 2015; 104:375-84. [PMID: 25823876 DOI: 10.1002/jbm.b.33373] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 11/25/2014] [Accepted: 01/09/2015] [Indexed: 01/18/2023]
Abstract
UNLABELLED Development of substituted 1,8-naphthalimides for photochemical cross-linking of biomolecules is the focus of this research. This study describes limited cross-linking of collagen in the artery wall to control recoil and buckling in arteries following balloon angioplasty. Isolated porcine arteries were overstretched (25%) with balloon angioplasty (BA) +/- light-activated naphthalimide treatment (NVS). Lumen size and recoil were measured as retention of stretch after angioplasty. Cross-sectional compliance and distensibility coefficients were measured as slope of cross-sectional area versus increasing hydrostatic pressure. Buckling was measured, with 30% axial pre-stretch and 200 mmHg, as deviation from the center line. Electron microscopy evaluation of collagen fibers was conducted. RESULTS Uninjured arteries have low compliance and low levels of buckling, whereas the BA-injured arteries demonstrated much greater compliance and buckling behavior. Treatment of the injured artery with NVS reduced buckling and demonstrated compliance midway between the two groups while retaining the increased luminal diameter imparted by angioplasty compared to untreated vessels. In summary, limited collagen cross-linking with NVS treatment resulted in lumen retention, as well as improved compliance without the accompanying rigidity and stiffness of conventional stent therapy or current cross-linking materials. This treatment shows great promise for dilation, repair and strengthening of arteries damaged by injury or vascular disease.
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Affiliation(s)
- Karen A Munger
- Avera Research Institute, Applied Research, Sioux Falls, South Dakota, 57017
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Saeid Khalafvand S, Han HC. Stability of carotid artery under steady-state and pulsatile blood flow: a fluid-structure interaction study. J Biomech Eng 2015; 137:061007. [PMID: 25761257 DOI: 10.1115/1.4030011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Indexed: 11/08/2022]
Abstract
It has been shown that arteries may buckle into tortuous shapes under lumen pressure, which in turn could alter blood flow. However, the mechanisms of artery instability under pulsatile flow have not been fully understood. The objective of this study was to simulate the buckling and post-buckling behaviors of the carotid artery under pulsatile flow using a fully coupled fluid-structure interaction (FSI) method. The artery wall was modeled as a nonlinear material with a two-fiber strain-energy function. FSI simulations were performed under steady-state flow and pulsatile flow conditions with a prescribed flow velocity profile at the inlet and different pressures at the outlet to determine the critical buckling pressure. Simulations were performed for normal (160 ml/min) and high (350 ml/min) flow rates and normal (1.5) and reduced (1.3) axial stretch ratios to determine the effects of flow rate and axial tension on stability. The results showed that an artery buckled when the lumen pressure exceeded a critical value. The critical mean buckling pressure at pulsatile flow was 17-23% smaller than at steady-state flow. For both steady-state and pulsatile flow, the high flow rate had very little effect (<5%) on the critical buckling pressure. The fluid and wall stresses were drastically altered at the location with maximum deflection. The maximum lumen shear stress occurred at the inner side of the bend and maximum tensile wall stresses occurred at the outer side. These findings improve our understanding of artery instability in vivo.
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Abstract
Background Tortuous arteries are often seen in patients with hypertension and atherosclerosis. While the mechanical stress in atherosclerotic plaque under lumen pressure has been studied extensively, the mechanical stability of atherosclerotic arteries and subsequent effect on the plaque stress remain unknown. To this end, we investigated the buckling and post-buckling behavior of model stenotic coronary arteries with symmetric and asymmetric plaque. Methods Buckling analysis for a model coronary artery with symmetric and asymmetric plaque was conducted using finite element analysis based on the dimensions and nonlinear anisotropic materials properties reported in the literature. Results Artery with asymmetric plaque had lower critical buckling pressure compared to the artery with symmetric plaque and control artery. Buckling increased the peak stress in the plaque and led to the development of a high stress concentration in artery with asymmetric plaque. Stiffer calcified tissue and severe stenosis increased the critical buckling pressure of the artery with asymmetric plaque. Conclusions Arteries with atherosclerotic plaques are prone to mechanical buckling which leads to a high stress concentration in the plaques that can possibly make the plaques prone to rupture.
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Effects of age on the physiological and mechanical characteristics of human femoropopliteal arteries. Acta Biomater 2015; 11:304-13. [PMID: 25301303 DOI: 10.1016/j.actbio.2014.09.050] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 08/23/2014] [Accepted: 09/29/2014] [Indexed: 01/07/2023]
Abstract
Surgical and interventional therapies for peripheral artery disease (PAD) are notorious for high rates of failure. Interactions between the artery and repair materials play an important role, but comprehensive data describing the physiological and mechanical characteristics of human femoropopliteal arteries are not available. Fresh femoropopliteal arteries were obtained from 70 human subjects (13-79 years old), and in situ vs. excised arterial lengths were measured. Circumferential and longitudinal opening angles were determined for proximal superficial femoral, proximal popliteal and distal popliteal arteries. Mechanical properties were assessed by multi-ratio planar biaxial extension, and experimental data were used to calculate physiological stresses and stretches, in situ axial force and anisotropy. Verhoeff-Van Gieson-stained axial and transverse arterial sections were used for histological analysis. Most specimens demonstrated nonlinear deformations and were more compliant longitudinally than circumferentially. In situ axial pre-stretch decreased 0.088 per decade of life. In situ axial force and axial stress also decreased with age, but circumferential physiological stress remained constant. Physiological circumferential stretch decreased 55-75% after 45 years of age. Histology demonstrated a thickened external elastic lamina with longitudinally oriented elastin that was denser in smaller, younger arteries. Axial elastin likely regulates axial pre-stretch to help accommodate the complex deformations required of the artery wall during locomotion. Degradation and fragmentation of elastin as a consequence of age, cyclic mechanical stress and atherosclerotic arterial disease may contribute to decreased in situ axial pre-stretch, predisposing to more severe kinking of the artery during limb flexion and loss of energy-efficient arterial function.
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