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Lang IM, Medda BK, Shaker R. Biomechanical increase in cervical esophageal wall tension during peristalsis. Am J Physiol Gastrointest Liver Physiol 2024; 326:G726-G735. [PMID: 38626405 DOI: 10.1152/ajpgi.00049.2024] [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: 02/14/2024] [Revised: 04/12/2024] [Accepted: 04/15/2024] [Indexed: 04/18/2024]
Abstract
During pharyngeal phase of swallowing, circumferential tension of the cervical esophagus (CTE) increases caused by a biomechanical process of laryngeal elevation pulling the cervical esophagus orad. The esophagus contracts longitudinally during esophageal peristalsis, therefore, we hypothesized that CTE increases during esophageal peristalsis by a biomechanical process. We investigated this hypothesis using 28 decerebrate cats instrumented with electromyographic (EMG) electrodes on the pharynx and esophagus, and esophageal manometry. We recorded CTE, distal esophageal longitudinal tension (DET), and orad laryngeal tension (OLT) using strain gauges. Peristalsis was stimulated by injecting saline into esophagus or nasopharynx. We investigated the effects of transecting the pharyngo-esophageal nerve (PEN), hypoglossal nerve (HG), or administering (10 mg/kg iv) hexamethonium (HEX). We found that the durations of CTE and DET increased and OLT decreased simultaneously during the total extent of esophageal peristalsis. CTE duration was highly correlated with DET but not esophageal EMG or manometry. The peak magnitudes of the DET and CTE were highly correlated. After HEX administration, peristalsis in the distal esophagus did not occur, and the duration of the CTE response decreased. PEN transection blocked the occurrence of cricopharyngeal or cervical esophageal response during peristalsis but had no significant effect on the CTE response. HG transection had no significant effect on CTE. We conclude that there is a significant CTE increase, independent of laryngeal elevation or esophageal muscle contraction, which occurs during esophageal peristalsis. This response is a biomechanical process caused by esophageal shortening that occurs during esophageal longitudinal contraction of esophageal peristalsis.NEW & NOTEWORTHY Circumferential tension of cervical esophagus (CTE) increases during esophageal peristalsis. CTE response is correlated with distal longitudinal tension on cervical esophagus during esophageal peristalsis but not laryngeal elevation or esophageal muscle contraction. CTE response is not blocked by transection of motor innervation of laryngeal elevating muscles or proximal esophagus but is temporally reduced after hexamethonium administration. We conclude that the CTE response is a biomechanical effect caused by longitudinal esophageal contraction during esophageal peristalsis.
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Affiliation(s)
- Ivan M Lang
- Dysphagia Research Laboratory, Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Bidyut K Medda
- Dysphagia Research Laboratory, Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Reza Shaker
- Dysphagia Research Laboratory, Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
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2
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Durcan C, Hossain M, Chagnon G, Perić D, Girard E. Characterization of the layer, direction and time-dependent mechanical behaviour of the human oesophagus and the effects of formalin preservation. J R Soc Interface 2024; 21:20230592. [PMID: 38593841 PMCID: PMC11003784 DOI: 10.1098/rsif.2023.0592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 03/05/2024] [Indexed: 04/11/2024] Open
Abstract
The mechanical characterization of the oesophagus is essential for applications such as medical device design, surgical simulations and tissue engineering, as well as for investigating the organ's pathophysiology. However, the material response of the oesophagus has not been established ex vivo in regard to the more complex aspects of its mechanical behaviour using fresh, human tissue: as of yet, in the literature, only the hyperelastic response of the intact wall has been studied. Therefore, in this study, the layer-dependent, anisotropic, visco-hyperelastic behaviour of the human oesophagus was investigated through various mechanical tests. For this, cyclic tests, with increasing stretch levels, were conducted on the layers of the human oesophagus in the longitudinal and circumferential directions and at two different strain rates. Additionally, stress-relaxation tests on the oesophageal layers were carried out in both directions. Overall, the results show discrete properties in each layer and direction, highlighting the importance of treating the oesophagus as a multi-layered composite material with direction-dependent behaviour. Previously, the authors conducted layer-dependent cyclic experimentation on formalin-embalmed human oesophagi. A comparison between the fresh and embalmed tissue response was carried out and revealed surprising similarities in terms of anisotropy, strain-rate dependency, stress-softening and hysteresis, with the main difference between the two preservation states being the magnitude of these properties. As formalin fixation is known to notably affect the formation of cross-links between the collagen of biological materials, the differences may reveal the influence of cross-links on the mechanical behaviour of soft tissues.
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Affiliation(s)
- Ciara Durcan
- Zienkiewicz Institute for Modelling, Data and Artificial Intelligence, Faculty of Science and Engineering, Swansea University, Swansea SA1 8EN, UK
- CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, Grenoble Alpes University, Grenoble 38000, France
| | - Mokarram Hossain
- Zienkiewicz Institute for Modelling, Data and Artificial Intelligence, Faculty of Science and Engineering, Swansea University, Swansea SA1 8EN, UK
| | - Grégory Chagnon
- CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, Grenoble Alpes University, Grenoble 38000, France
| | - Djordje Perić
- Zienkiewicz Institute for Modelling, Data and Artificial Intelligence, Faculty of Science and Engineering, Swansea University, Swansea SA1 8EN, UK
| | - Edouard Girard
- CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, Grenoble Alpes University, Grenoble 38000, France
- Laboratoire d’Anatomie des Alpes Françaises, Grenoble Alpes University, Grenoble, France
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Durcan C, Hossain M, Chagnon G, Perić D, Girard E. Mechanical experimentation of the gastrointestinal tract: a systematic review. Biomech Model Mechanobiol 2024; 23:23-59. [PMID: 37935880 PMCID: PMC10901955 DOI: 10.1007/s10237-023-01773-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 09/10/2023] [Indexed: 11/09/2023]
Abstract
The gastrointestinal (GI) organs of the human body are responsible for transporting and extracting nutrients from food and drink, as well as excreting solid waste. Biomechanical experimentation of the GI organs provides insight into the mechanisms involved in their normal physiological functions, as well as understanding of how diseases can cause disruption to these. Additionally, experimental findings form the basis of all finite element (FE) modelling of these organs, which have a wide array of applications within medicine and engineering. This systematic review summarises the experimental studies that are currently in the literature (n = 247) and outlines the areas in which experimentation is lacking, highlighting what is still required in order to more fully understand the mechanical behaviour of the GI organs. These include (i) more human data, allowing for more accurate modelling for applications within medicine, (ii) an increase in time-dependent studies, and (iii) more sophisticated in vivo testing methods which allow for both the layer- and direction-dependent characterisation of the GI organs. The findings of this review can also be used to identify experimental data for the readers' own constitutive or FE modelling as the experimental studies have been grouped in terms of organ (oesophagus, stomach, small intestine, large intestine or rectum), test condition (ex vivo or in vivo), number of directions studied (isotropic or anisotropic), species family (human, porcine, feline etc.), tissue condition (intact wall or layer-dependent) and the type of test performed (biaxial tension, inflation-extension, distension (pressure-diameter), etc.). Furthermore, the studies that investigated the time-dependent (viscoelastic) behaviour of the tissues have been presented.
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Affiliation(s)
- Ciara Durcan
- Zienkiewicz Centre for Modelling, Data and AI, Faculty of Science and Engineering, Swansea University, Swansea, SA1 8EN, UK
- Université Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France
| | - Mokarram Hossain
- Zienkiewicz Centre for Modelling, Data and AI, Faculty of Science and Engineering, Swansea University, Swansea, SA1 8EN, UK.
| | - Grégory Chagnon
- Université Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France
| | - Djordje Perić
- Zienkiewicz Centre for Modelling, Data and AI, Faculty of Science and Engineering, Swansea University, Swansea, SA1 8EN, UK
| | - Edouard Girard
- Université Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France
- Laboratoire d'Anatomie des Alpes Françaises, Université Grenoble Alpes, Grenoble, France
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4
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Estrada Mira S, García-Briega MI, Gómez Ribelles JL, Restrepo Munera LM. Viscoelastic Properties of Acellular Matrices of Porcine Esophageal Mucosa and Comparison with Acellular Matrices of Porcine Small Intestine Submucosa and Bovine Pericardium. MATERIALS (BASEL, SWITZERLAND) 2023; 17:134. [PMID: 38203987 PMCID: PMC10779732 DOI: 10.3390/ma17010134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 12/18/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024]
Abstract
The aim of this study was to compare the viscoelastic properties of a decellularized mesh from the porcine esophagus, prepared by our group, with two commercial acellular tissues derived from porcine small intestine submucosa and bovine pericardium for use in medical devices. The tissues' viscoelastic properties were characterized by creep tests in tension, applying the load in the direction of the fibers or the transverse direction, and also by dynamic-shear mechanical tests between parallel plates or in tension at frequencies between 0.1 and 35 Hz. All the tests were performed in triplicate at a constant temperature of 37 °C immersed in distilled water. The tissues' surface and cross-sectional microstructure were observed by scanning electron microscopy (SEM) to characterize the orientation of the fibers. The matrices of the porcine esophagus present an elastic modulus in the order of 60 MPa when loaded in the longitudinal direction while those of the porcine intestine submucosa and bovine pericardium have an elastic modulus below 5 MPa. Nevertheless, the shear modulus of bovine pericardium nearly triplicates that of the esophageal matrix. The viscoelasticity of decellularized esophageal mucosa is characterized by a fast change in the creep compliance with time. The slope of the creep curve in the double logarithmic plot is twice that of the control samples. These results are consistent with the microstructure observed under electron microscopy regarding the orientation of the fibers that make up the matrices.
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Affiliation(s)
- Sergio Estrada Mira
- Tissue Engineering and Cells Therapy Group (GITTC), School of Medicine, University of Antioquia, Medellin 050010, Colombia; (S.E.M.); (L.M.R.M.)
- Cell Therapy and Biobank, Alma Mater Hospital of Antioquia, University of Antioquia, Medellin 050010, Colombia
| | - María Inmaculada García-Briega
- Centre for Biomaterials and Tissue Engineering (CBIT), Universitat Politècnica de València, 46022 Valencia, Spain;
- Centro de Investigación Biomédica en Red de Bioingeniería Biomateriales y Nanomedicina (CIBER-BBN), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - José Luis Gómez Ribelles
- Centre for Biomaterials and Tissue Engineering (CBIT), Universitat Politècnica de València, 46022 Valencia, Spain;
- Centro de Investigación Biomédica en Red de Bioingeniería Biomateriales y Nanomedicina (CIBER-BBN), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Luz M. Restrepo Munera
- Tissue Engineering and Cells Therapy Group (GITTC), School of Medicine, University of Antioquia, Medellin 050010, Colombia; (S.E.M.); (L.M.R.M.)
- Cell Therapy and Biobank, Alma Mater Hospital of Antioquia, University of Antioquia, Medellin 050010, Colombia
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5
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Halder S, Johnson EM, Yamasaki J, Kahrilas PJ, Markl M, Pandolfino JE, Patankar NA. MRI-MECH: mechanics-informed MRI to estimate esophageal health. Front Physiol 2023; 14:1195067. [PMID: 37362445 PMCID: PMC10289887 DOI: 10.3389/fphys.2023.1195067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 05/23/2023] [Indexed: 06/28/2023] Open
Abstract
Dynamic magnetic resonance imaging (MRI) is a popular medical imaging technique that generates image sequences of the flow of a contrast material inside tissues and organs. However, its application to imaging bolus movement through the esophagus has only been demonstrated in few feasibility studies and is relatively unexplored. In this work, we present a computational framework called mechanics-informed MRI (MRI-MECH) that enhances that capability, thereby increasing the applicability of dynamic MRI for diagnosing esophageal disorders. Pineapple juice was used as the swallowed contrast material for the dynamic MRI, and the MRI image sequence was used as input to the MRI-MECH. The MRI-MECH modeled the esophagus as a flexible one-dimensional tube, and the elastic tube walls followed a linear tube law. Flow through the esophagus was governed by one-dimensional mass and momentum conservation equations. These equations were solved using a physics-informed neural network. The physics-informed neural network minimized the difference between the measurements from the MRI and model predictions and ensured that the physics of the fluid flow problem was always followed. MRI-MECH calculated the fluid velocity and pressure during esophageal transit and estimated the mechanical health of the esophagus by calculating wall stiffness and active relaxation. Additionally, MRI-MECH predicted missing information about the lower esophageal sphincter during the emptying process, demonstrating its applicability to scenarios with missing data or poor image resolution. In addition to potentially improving clinical decisions based on quantitative estimates of the mechanical health of the esophagus, MRI-MECH can also be adapted for application to other medical imaging modalities to enhance their functionality.
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Affiliation(s)
- Sourav Halder
- Theoretical and Applied Mechanics Program, McCormick School of Engineering, Northwestern University, Evanston, IL, United States
| | - Ethan M Johnson
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Jun Yamasaki
- Department of Mechanical Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL, United States
| | - Peter J Kahrilas
- Department of Medicine, Feinberg School of Medicine, Division of Gastroenterology and Hepatology, Northwestern University, Chicago, IL, United States
| | - Michael Markl
- Department of Mechanical Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL, United States
| | - John E Pandolfino
- Department of Medicine, Feinberg School of Medicine, Division of Gastroenterology and Hepatology, Northwestern University, Chicago, IL, United States
| | - Neelesh A Patankar
- Theoretical and Applied Mechanics Program, McCormick School of Engineering, Northwestern University, Evanston, IL, United States
- Department of Mechanical Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL, United States
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6
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Lang IM, Medda BK, Shaker R. Biomechanical effects of esophageal elongation on the circumferential tension of the cervical esophagus in vivo. J Appl Physiol (1985) 2023; 134:549-557. [PMID: 36656979 PMCID: PMC9970647 DOI: 10.1152/japplphysiol.00667.2022] [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: 11/04/2022] [Revised: 01/13/2023] [Accepted: 01/18/2023] [Indexed: 01/21/2023] Open
Abstract
Evidence obtained ex vivo suggests that physical elongation of the esophagus increases esophageal circumferential stress-strain ratio, but it is unknown whether this biomechanical effect alters esophageal function in vivo. We investigated the effects of physical or physiological elongation of the cervical esophagus on basal and active circumferential tension in vivo. The esophagus was elongated, using 29 decerebrate cats, either physically by distal physical extension of the esophagus or physiologically by stimulating the hypoglossal nerve, which activates laryngeal elevating muscles that elongate the esophagus. Hyoid, pharyngeal, and esophageal muscles were instrumented with electromyogram (EMG) electrodes and/or strain gauge force transducers. Esophageal intraluminal manometry was also recorded. We found that physical or physiological elongation of the cervical esophagus increased esophageal circumferential basal as well as active tension initiated by electrical stimulation of the pharyngo-esophageal nerve or the esophageal muscle directly, but did not increase esophageal intraluminal pressure or EMG activity. The esophageal circumferential response to the esophago-esophageal contractile reflex was increased by distal physical elongation, but not orad physiological elongation. We conclude that physical or physiological elongation of the esophagus significantly increases esophageal circumferential basal and active tension without muscle activation. We hypothesize that this effect is caused by an increase in esophageal stress-strain ratio by a biomechanical process, which increases circumferential wall stiffness. The increase in esophageal circumferential stiffness increases passive tension and the effectiveness of active tension. This increase in cervical esophageal circumferential stiffness may alter esophageal function.NEW & NOTEWORTHY Physical or physiological esophageal elongation increases esophageal circumferential active or passive tension by a biomechanical process, which causes a decrease in esophageal circumferential elasticity. This increased stiffness of the esophageal wall likely promotes esophageal bolus flow during various esophageal functions.
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Affiliation(s)
- Ivan M Lang
- Dysphagia Research Laboratory, Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Bidyut K Medda
- Dysphagia Research Laboratory, Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Reza Shaker
- Dysphagia Research Laboratory, Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
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7
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Lang IM, Medda BK, Kern M, Shaker R. A biomechanical response of the esophagus participates in swallowing. Am J Physiol Gastrointest Liver Physiol 2023; 324:G131-G141. [PMID: 36511513 PMCID: PMC9870579 DOI: 10.1152/ajpgi.00219.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 11/30/2022] [Accepted: 12/06/2022] [Indexed: 01/07/2023]
Abstract
Evidence suggests that a biomechanical process participates in esophageal function, but no such function has yet been identified. We investigated the role of a biomechanical process during swallowing in 30 decerebrate cats instrumented using electromyogram (EMG) electrodes, strain gauge force transducers, and manometry. We found that the cervical esophagus has a short-lasting circumferential tension response during the pharyngeal phase of swallowing (CTPP), and a concomitant EMG response. The CTPP magnitude was correlated with magnitudes of contraction of the geniohyoideus, laryngeal elevation force, and esophageal orad elongation force. The magnitude of the CTPP was not correlated with the peak or area under the curve of the concomitant esophageal EMG response. Restricting laryngeal elevation by physical force or transecting the hypoglossal nerves decreased or eliminated the CTPP during swallowing. Elongation of the distal cervical esophagus increased basal circumferential cervical esophageal tension as well as the CTPP. Transecting the vagus or pharyngoesophageal nerves, or administering hexosamine intravenously, had no significant effect on CTPP. We conclude that CTPP is a response to esophageal elongation during laryngeal elevation during the pharyngeal phase of swallowing, which is not caused by muscle contraction or mediated by the nervous system. The CTPP may assist in the distal movement of boluses before activation of the esophageal phase of swallowing, and may serve to prevent esophagopharyngeal reflux. We hypothesize that the CTPP is a biomechanical decrease in elasticity of the circumferential connective tissue of the cervical esophagus caused by the stress of cervical esophageal elongation.NEW & NOTEWORTHY The pharyngeal phase of swallowing includes increased circumferential tension of the cervical esophagus during the pharyngeal phase of swallowing (CTPP). The CTPP is a biomechanical response caused by elongation of the esophagus during laryngeal elevation, and is not caused by muscle contraction or mediated by the nervous system. The CTPP may assist in the distal movement of boluses before activation of the esophageal phase of swallowing, and may serve to prevent esophagopharyngeal reflux.
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Affiliation(s)
- Ivan M Lang
- Dysphagia Research Laboratory, Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Bidyut K Medda
- Dysphagia Research Laboratory, Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Mark Kern
- Dysphagia Research Laboratory, Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Reza Shaker
- Dysphagia Research Laboratory, Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
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Rosalia L, Hallou A, Cochrane L, Savin T. A magnetically actuated, optically sensed tensile testing method for mechanical characterization of soft biological tissues. SCIENCE ADVANCES 2023; 9:eade2522. [PMID: 36630495 PMCID: PMC9833656 DOI: 10.1126/sciadv.ade2522] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 12/10/2022] [Indexed: 06/17/2023]
Abstract
Mechanical properties of soft biological tissues play a critical role in physiology and disease, affecting cell behavior and fate decisions and contributing to tissue development, maintenance, and repair. Limitations of existing tools prevent a comprehensive characterization of soft tissue biomechanics, hindering our understanding of these fundamental processes. Here, we develop an instrument for high-fidelity uniaxial tensile testing of soft biological tissues in controlled environmental conditions, which is based on the closed-loop interaction between an electromagnetic actuator and an optical strain sensor. We first validate the instrument using synthetic elastomers characterized via conventional methods; then, we leverage the proposed device to investigate the mechanical properties of murine esophageal tissue and, individually, of each of its constitutive layers, namely, the epithelial, connective, and muscle tissues. The enhanced reliability of this instrument makes it an ideal platform for future wide-ranging studies of the mechanics of soft biological tissues.
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Affiliation(s)
- Luca Rosalia
- Health Sciences and Technology Program, Harvard-MIT, Cambridge, MA, USA
- Institute for Medical Engineering and Science, MIT, Cambridge, MA, USA
| | - Adrien Hallou
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK
- Wellcome/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge, UK
- Wellcome/Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK
| | | | - Thierry Savin
- Department of Engineering, University of Cambridge, Cambridge, UK
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Virtual disease landscape using mechanics-informed machine learning: Application to esophageal disorders. Artif Intell Med 2022; 134:102435. [PMID: 36462900 DOI: 10.1016/j.artmed.2022.102435] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 10/17/2022] [Accepted: 10/28/2022] [Indexed: 12/14/2022]
Abstract
Esophageal disorders are related to the mechanical properties and function of the esophageal wall. Therefore, to understand the underlying fundamental mechanisms behind various esophageal disorders, it is crucial to map mechanical behavior of the esophageal wall in terms of mechanics-based parameters corresponding to altered bolus transit and increased intrabolus pressure. We present a hybrid framework that combines fluid mechanics and machine learning to identify the underlying physics of various esophageal disorders (motility disorders, eosinophilic esophagitis, reflux disease, scleroderma esophagus) and maps them onto a parameter space which we call the virtual disease landscape (VDL). A one-dimensional inverse model processes the output from an esophageal diagnostic device called the functional lumen imaging probe (FLIP) to estimate the mechanical "health" of the esophagus by predicting a set of mechanics-based parameters such as esophageal wall stiffness, muscle contraction pattern and active relaxation of esophageal wall. The mechanics-based parameters were then used to train a neural network that consists of a variational autoencoder that generated a latent space and a side network that predicted mechanical work metrics for estimating esophagogastric junction motility. The latent vectors along with a set of discrete mechanics-based parameters define the VDL and formed clusters corresponding to specific esophageal disorders. The VDL not only distinguishes among disorders but also displayed disease progression over time. Finally, we demonstrated the clinical applicability of this framework for estimating the effectiveness of a treatment and tracking patients' condition after a treatment.
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10
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Ramaraju H, Sferra SR, Kunisaki SM, Hollister SJ. Finite element analysis of esophageal atresia repair with biodegradable polymer sleeves. J Mech Behav Biomed Mater 2022; 133:105349. [DOI: 10.1016/j.jmbbm.2022.105349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 06/20/2022] [Accepted: 06/28/2022] [Indexed: 10/17/2022]
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11
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Patel B, Gizzi A, Hashemi J, Awakeem Y, Gregersen H, Kassab G. Biomechanical constitutive modeling of the gastrointestinal tissues: a systematic review. MATERIALS & DESIGN 2022; 217:110576. [PMID: 35935127 PMCID: PMC9351365 DOI: 10.1016/j.matdes.2022.110576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The gastrointestinal (GI) tract is a continuous channel through the body that consists of the esophagus, the stomach, the small intestine, the large intestine, and the rectum. Its primary functions are to move the intake of food for digestion before storing and ultimately expulsion of feces. The mechanical behavior of GI tissues thus plays a crucial role for GI function in health and disease. The mechanical properties are characterized by a biomechanical constitutive model, which is a mathematical representation of the relation between load and deformation in a tissue. Hence, validated biomechanical constitutive models are essential to characterize and simulate the mechanical behavior of the GI tract. Here, a systematic review of these constitutive models is provided. This review is limited to studies where a model of the strain energy function is proposed to characterize the stress-strain relation of a GI tissue. Several needs are identified for more advanced modeling including: 1) Microstructural models that provide actual structure-function relations; 2) Validation of coupled electro-mechanical models accounting for active muscle contractions; 3) Human data to develop and validate models. The findings from this review provide guidelines for using existing constitutive models as well as perspective and directions for future studies.
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Affiliation(s)
- Bhavesh Patel
- California Medical Innovations Institute, 11107 Roselle St, San Diego, CA 92121, USA
| | - Alessio Gizzi
- Department of Engineering, Campus Bio-Medico University of Rome, Via A. del Portillo 21, 00128 Rome, IT
| | - Javad Hashemi
- California Medical Innovations Institute, 11107 Roselle St, San Diego, CA 92121, USA
| | - Yousif Awakeem
- California Medical Innovations Institute, 11107 Roselle St, San Diego, CA 92121, USA
| | - Hans Gregersen
- California Medical Innovations Institute, 11107 Roselle St, San Diego, CA 92121, USA
| | - Ghassan Kassab
- California Medical Innovations Institute, 11107 Roselle St, San Diego, CA 92121, USA
- Corresponding author , Tel: 001-858-249-7400, Fax: 001-858-249-7419, (Ghassan Kassab)
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12
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Durcan C, Hossain M, Chagnon G, Perić D, Bsiesy L, Karam G, Girard E. Experimental investigations of the human oesophagus: anisotropic properties of the embalmed muscular layer under large deformation. Biomech Model Mechanobiol 2022; 21:1169-1186. [PMID: 35477829 PMCID: PMC9045687 DOI: 10.1007/s10237-022-01583-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 03/31/2022] [Indexed: 11/24/2022]
Abstract
The oesophagus is a primarily mechanical organ whose material characterisation would aid in the investigation of its pathophysiology, help in the field of tissue engineering, and improve surgical simulations and the design of medical devices. However, the layer-dependent, anisotropic properties of the organ have not been investigated using human tissue, particularly in regard to its viscoelastic and stress-softening behaviour. Restrictions caused by the COVID-19 pandemic meant that fresh human tissue was not available for dissection. Therefore, in this study, the layer-specific material properties of the human oesophagus were investigated through ex vivo experimentation of the embalmed muscularis propria layer. For this, a series of uniaxial tension cyclic tests with increasing stretch levels were conducted at two different strain rates. The muscular layers from three different cadaveric specimens were tested in both the longitudinal and circumferential directions. The results displayed highly nonlinear and anisotropic behaviour, with both time- and history-dependent stress-softening. The longitudinal direction was found to be stiffer than the circumferential direction at both strain rates. Strain rate-dependent behaviour was apparent, with an increase in strain rate resulting in an increase in stiffness in both directions. Histological analysis was carried out via various staining methods; the results of which were discussed with regard to the experimentally observed stress-stretch response. Finally, the behaviour of the muscularis propria was simulated using a matrix-fibre model able to capture the various mechanical phenomena exhibited, the fibre orientation of which was driven by the histological findings of the study.
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Affiliation(s)
- Ciara Durcan
- Zienkiewicz Centre for Computational Engineering, Faculty of Science and Engineering, Swansea University, Swansea, SA1 8EN, UK.,Univ. Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France
| | - Mokarram Hossain
- Zienkiewicz Centre for Computational Engineering, Faculty of Science and Engineering, Swansea University, Swansea, SA1 8EN, UK.
| | - Grégory Chagnon
- Univ. Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France
| | - Djordje Perić
- Zienkiewicz Centre for Computational Engineering, Faculty of Science and Engineering, Swansea University, Swansea, SA1 8EN, UK
| | - Lara Bsiesy
- Univ. Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France
| | - Georges Karam
- Univ. Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France
| | - Edouard Girard
- Univ. Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France.,Laboratoire d'Anatomie des Alpes Françaises, Univ. Grenoble Alpes, Grenoble, France
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13
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Ren P, Deng X, Li K, Li G, Li W. 3D biomechanical properties of the layered esophagus: Fung-type SEF and new constitutive model. Biomech Model Mechanobiol 2021; 20:1775-1788. [PMID: 34132899 DOI: 10.1007/s10237-021-01476-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 06/04/2021] [Indexed: 02/05/2023]
Abstract
BACKGROUND AND PURPOSE Most current studies on the passive biomechanical properties of esophageal tissues directly use the exponential strain energy function (SEF) to fit and calculate the constants of the constitutive equation. In the context of the extensive application of exponential SEF, in-depth research on the exponential SEF is still lacking. The purpose of this study is to combine the exponential function with the polynomial SEF to obtain the most suitable constitutive equation to describe the three-dimensional passive behavior of the esophagus. METHODS fresh pig esophagus with a length of 13 cm in the middle position was selected as esophageal samples. The esophageal sample was separated into muscular layer and mucosal layer with surgical scissors. Stretch-inflation mechanical tests of the intact esophagus, esophageal muscular, and esophageal mucosa were carried out on a triaxial test machine. The external radius, axial force, and internal pressure were recorded simultaneously. The seven-parameter Fung-type SEF and several new SEFs combining polynomials and exponents were used to fit the experimental data curves. RESULTS The stretch-inflation test data and the morphometric parameters at the zero-stress state of the layered esophagus were obtained. The new SEF with polynomial and exponential combination is more suitable to describe describing the three-dimensional passive biomechanical properties of esophageal tissue. Among them, New-Fung13 SEF is more suitable for describing the passive biomechanical properties of intact esophageal tissue, Sokolis-Fung13 SEF is more suitable for the esophageal muscle layer, and New-Fung10 SEF is more suitable for the esophageal mucosa. The constitutive parameters of the optimal constitutive model for each layer of the esophagus were obtained.
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Affiliation(s)
- Pan Ren
- Tribology Research Institute, Key Laboratory for Advanced Technology of Materials of Ministry of Education, Southwest Jiaotong University, Chengdu, 610031, China
| | - Xing Deng
- Tribology Research Institute, Key Laboratory for Advanced Technology of Materials of Ministry of Education, Southwest Jiaotong University, Chengdu, 610031, China
| | - KeZhou Li
- Department of Pancreatic Surgery, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - GuiHao Li
- Tribology Research Institute, Key Laboratory for Advanced Technology of Materials of Ministry of Education, Southwest Jiaotong University, Chengdu, 610031, China
| | - Wei Li
- Tribology Research Institute, Key Laboratory for Advanced Technology of Materials of Ministry of Education, Southwest Jiaotong University, Chengdu, 610031, China.
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Goyal RP, Gangwar AK, Khangembam SD, Yadav VK, Kumar R, Verma RK, Kumar N. Decellularization of caprine esophagus using fruit pericarp extract of Sapindus mukorossi. Cell Tissue Bank 2021; 23:79-92. [PMID: 33768473 DOI: 10.1007/s10561-021-09916-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 03/10/2021] [Indexed: 11/24/2022]
Abstract
Biological detergents like sodium deoxycholate, sodium dodecyl sulphate and Triton X-100 impairs the collagenous and non-collagenous proteins, glycosaminoglycans and growth factors. Further, certain chemical and enzymes are responsible for residual cytotoxicity in the decellularized extracellular matrix. The main focus of this study was to explore the decellularization property of soap nut pericarp extract (SPE) for development of decellularized tubular esophageal scaffold. For this 2.5, 5.0 and 10% concentrations of SPE were used for decellularization of caprine esophageal tissues. Histological analysis of hematoxylin and eosin and Masson's trichrome stained tissue samples confirmed decellularization with preservation of extracellular matrix microarchitecture. Scanning electron microscopic images of luminal surface of decellularized esophageal matrix showed randomly oriented collagen fibres with large interconnected pores and cells were absent. However, the external surface was more textured with fibrous structures and collagen fibres were well preserved. DAPI stained decellularized tissues revealed complete removal of nuclear components, verified by DNA content measurement and SDS-PAGE. The FTIR spectra of decellularized esophagus shows absorption peaks of amide A, B, I, II and III. Elastic modulus of the decellularized esophagus scaffolds increased (P > 0.05) as compared to native tissues. Histological and scanning electron microscopic evaluation of in vitro seeded scaffolds showed attachment and growth of primary chicken embryo fibroblasts over and within the decellularized scaffolds. It was concluded that 5% SPE is ideal for preparation of cytocompatible decellularized caprine esophageal scaffold with well-preserved extracellular matrix architecture and, may be used as an alternative to biological detergents and other chemicals.
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Affiliation(s)
- Ravi Prakash Goyal
- Department of Veterinary Surgery and Radiology, College of Veterinary Science and Animal Husbandry, Acharya Narendra Dev University of Agriculture and Technology, Kumarganj, Ayodhya, Uttar Pradesh, 224 229, India
| | - Anil Kumar Gangwar
- Department of Veterinary Surgery and Radiology, College of Veterinary Science and Animal Husbandry, Acharya Narendra Dev University of Agriculture and Technology, Kumarganj, Ayodhya, Uttar Pradesh, 224 229, India.
| | - Sangeeta Devi Khangembam
- Department of Veterinary Surgery and Radiology, College of Veterinary Science and Animal Husbandry, Acharya Narendra Dev University of Agriculture and Technology, Kumarganj, Ayodhya, Uttar Pradesh, 224 229, India
| | - Vipin Kumar Yadav
- Department of Veterinary Surgery and Radiology, College of Veterinary Science and Animal Husbandry, Acharya Narendra Dev University of Agriculture and Technology, Kumarganj, Ayodhya, Uttar Pradesh, 224 229, India
| | - Rabindra Kumar
- Department of Veterinary Gynaecology and Obstetrics, College of Veterinary Science and Animal Husbandry, Acharya Narendra Dev University of Agriculture and Technology, Kumarganj, Ayodhya, Uttar Pradesh, 224 229, India
| | - Rajesh Kumar Verma
- Department of Veterinary Clinical Complex, College of Veterinary Science and Animal Husbandry, Acharya Narendra Dev University of Agriculture and Technology, Kumarganj, Ayodhya, Uttar Pradesh, 224 229, India
| | - Naveen Kumar
- Division of Surgery, Indian Veterinary Research Institute, Izatnagar, Uttar Pradesh, 243122, India
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Biomechanical Force Prediction for Lengthening of Small Intestine during Distraction Enterogenesis. Bioengineering (Basel) 2020; 7:bioengineering7040140. [PMID: 33171760 PMCID: PMC7711478 DOI: 10.3390/bioengineering7040140] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/04/2020] [Accepted: 10/28/2020] [Indexed: 11/16/2022] Open
Abstract
Distraction enterogenesis has been extensively studied as a potential treatment for short bowel syndrome, which is the most common form of intestinal failure. Different strategies including parenteral nutrition and surgical lengthening to manage patients with short bowel syndrome are associated with high complication rates. More recently, self-expanding springs have been used to lengthen the small intestine using an intraluminal axial mechanical force, where this biomechanical force stimulates the growth and elongation of the small intestine. Differences in physical characteristics of patients with short bowel syndrome would require a different mechanical force—this is crucial in order to achieve an efficient and safe lengthening outcome. In this study, we aimed to predict the required mechanical force for each potential intestinal size. Based on our previous experimental observations and computational findings, we integrated our experimental measurements of patient biometrics along with mechanical characterization of the soft tissue into our numerical simulations to develop a series of computational models. These computational models can predict the required mechanical force for any potential patient where this can be advantageous in predicting an individual’s tissue response to spring-mediated distraction enterogenesis and can be used toward a safe delivery of the mechanical force.
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Farhat W, Chatelain F, Marret A, Faivre L, Arakelian L, Cattan P, Fuchs A. Trends in 3D bioprinting for esophageal tissue repair and reconstruction. Biomaterials 2020; 267:120465. [PMID: 33129189 DOI: 10.1016/j.biomaterials.2020.120465] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 10/15/2020] [Accepted: 10/18/2020] [Indexed: 02/08/2023]
Abstract
In esophageal pathologies, such as esophageal atresia, cancers, caustic burns, or post-operative stenosis, esophageal replacement is performed by using parts of the gastrointestinal tract to restore nutritional autonomy. However, this surgical procedure most often does not lead to complete functional recovery and is instead associated with many complications resulting in a decrease in the quality of life and survival rate. Esophageal tissue engineering (ETE) aims at repairing the defective esophagus and is considered as a promising therapeutic alternative. Noteworthy progress has recently been made in the ETE research area but strong challenges remain to replicate the structural and functional integrity of the esophagus with the approaches currently being developed. Within this context, 3D bioprinting is emerging as a new technology to facilitate the patterning of both cellular and acellular bioinks into well-organized 3D functional structures. Here, we present a comprehensive overview of the recent advances in tissue engineering for esophageal reconstruction with a specific focus on 3D bioprinting approaches in ETE. Current biofabrication techniques and bioink features are highlighted, and these are discussed in view of the complexity of the native esophagus that the designed substitute needs to replace. Finally, perspectives on recent strategies for fabricating other tubular organ substitutes via 3D bioprinting are discussed briefly for their potential in ETE applications.
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Affiliation(s)
- Wissam Farhat
- Université de Paris, Inserm, U976 HIPI, F-75006, Paris, France; AP-HP, Hôpital Saint-Louis, 1 avenue Vellefaux, F-75010, Paris, France; CEA, IRIG, F-38000, Grenoble, France
| | - François Chatelain
- Université de Paris, Inserm, U976 HIPI, F-75006, Paris, France; AP-HP, Hôpital Saint-Louis, 1 avenue Vellefaux, F-75010, Paris, France; CEA, IRIG, F-38000, Grenoble, France
| | - Auriane Marret
- Université de Paris, Inserm, U976 HIPI, F-75006, Paris, France; AP-HP, Hôpital Saint-Louis, 1 avenue Vellefaux, F-75010, Paris, France; CEA, IRIG, F-38000, Grenoble, France
| | - Lionel Faivre
- Université de Paris, Inserm, U976 HIPI, F-75006, Paris, France; Assistance Publique - Hôpitaux de Paris, Unité de Thérapie Cellulaire, Hôpital Saint-Louis, Paris, France
| | - Lousineh Arakelian
- Université de Paris, Inserm, U976 HIPI, F-75006, Paris, France; Assistance Publique - Hôpitaux de Paris, Unité de Thérapie Cellulaire, Hôpital Saint-Louis, Paris, France
| | - Pierre Cattan
- Université de Paris, Inserm, U976 HIPI, F-75006, Paris, France; Assistance Publique - Hôpitaux de Paris, Service de Chirurgie Digestive, Hôpital Saint-Louis, Paris, France
| | - Alexandra Fuchs
- Université de Paris, Inserm, U976 HIPI, F-75006, Paris, France; AP-HP, Hôpital Saint-Louis, 1 avenue Vellefaux, F-75010, Paris, France; CEA, IRIG, F-38000, Grenoble, France.
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17
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Tagkalos E, Lindner A, Gruber G, Lang H, Heimann A, Grimminger PP, Muensterer OJ, Oetzmann von Sochaczewski C. Using simple interrupted suture anastomoses may impair translatability of experimental rodent oesophageal surgery. Acta Chir Belg 2020; 120:310-314. [PMID: 31012385 DOI: 10.1080/00015458.2019.1610263] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Background/purpose: Irreproducibility and missing translatability are major drawbacks in experimental animal studies. Hand-sewn anastomoses in oesophageal surgery are usually continuous, whereas those in experimental oesophageal surgery are widely performed using the simple interrupted technique. It has been implicated to be inferior in tolerating anastomotic tension, which we aimed to test in rats due to their importance as an animal model in oesophageal surgery.Methods: We determined linear breaking strengths for the native oesophagus (n = 10), the simple interrupted suture anastomosis (n = 11), and the simple stitch (n = 9) in 8-week old Sprague-Dawley rats. Experiments were powered to a margin of error of 10% around the results of exploratory investigations. The comparison of anastomotic resilience between native organ and simple interrupted suture anastomosis was a priori powered to 99%.Results: Native oesophagi sustained traction forces of 4.25 N (95% CI: 4.03-4.58 N), but the simple interrupted suture anastomosis had only 38.6% (Δ= -2.78 N, 95% CI: -2.46 to -3.11 N, p < .0001) of the resilience of native oesophagi.Conclusions: Oesophageal division and re-anastomosis markedly decreases resilience to traction forces compared to the native organ. This effect is even more pronounced in rats compared to other species and might impair transferability of results.
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Affiliation(s)
- Evangelos Tagkalos
- Department of General, Visceral and Transplant Surgery Universitätsmedizin Mainz der Johannes Gutenberg-Universität, Mainz, Germany
| | - Andreas Lindner
- Department of Paediatric Surgery, Universitätsmedizin Mainz der Johannes Gutenberg-Universität, Mainz, Germany
| | - Gudrun Gruber
- Translational Animal Research Centre Johannes Gutenberg-Universität Mainz, Mainz, Germany
| | - Hauke Lang
- Department of General, Visceral and Transplant Surgery Universitätsmedizin Mainz der Johannes Gutenberg-Universität, Mainz, Germany
| | - Axel Heimann
- Institute of Neurosurgical Pathophysiology Universitätsmedizin Mainz der Johannes Gutenberg-Universität, Mainz, Germany
| | - Peter P. Grimminger
- Department of General, Visceral and Transplant Surgery Universitätsmedizin Mainz der Johannes Gutenberg-Universität, Mainz, Germany
| | - Oliver J. Muensterer
- Department of Paediatric Surgery, Universitätsmedizin Mainz der Johannes Gutenberg-Universität, Mainz, Germany
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Hosseini HS, Taylor JS, Wood LS, Dunn JC. Biomechanics of small intestine during distraction enterogenesis with an intraluminal spring. J Mech Behav Biomed Mater 2020; 101:103413. [DOI: 10.1016/j.jmbbm.2019.103413] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Revised: 06/13/2019] [Accepted: 08/31/2019] [Indexed: 12/25/2022]
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19
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Goudard Y, Masson C, Ammar Y, Bège T. Biomechanical characterization of human small bowel wall under inflation conditions. Comput Methods Biomech Biomed Engin 2019. [DOI: 10.1080/10255842.2020.1714243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Y. Goudard
- Hôpital d’Instruction des Armées Laveran 4, bd Alphonse, Laveran Marseille cedex, France
- Aix-Marseille Univ, Marseille, France
| | - C. Masson
- Aix-Marseille Univ, Marseille, France
| | - Y. Ammar
- Aix-Marseille Univ, Marseille, France
| | - T. Bège
- Aix-Marseille Univ, Marseille, France
- department of general surgery, Aix Marseille Université, AP-HM, North Hospital, France
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20
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Dargar S, Kruger U, De S. In vivo Layer-specific Mechanical Characterization of Porcine Stomach Tissue using Ultrasound Elastography. J Biomech Eng 2019; 141:2729411. [PMID: 30901383 DOI: 10.1115/1.4043259] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Indexed: 12/14/2022]
Abstract
This paper presents in vivo mechanical characterization of the muscularis, submucosa and mucosa of the porcine stomach wall under large deformation loading. This is important for the development of gastrointestinal pathology-specific surgical intervention techniques. The study is based on testing the cardiac and fundic glandular stomach regions using a custom-developed compression elastography setup. Particular attention has been paid to elucidate the heterogeneity and anisotropy of tissue response. A Fung hyperelastic material model has been used to model the mechanical response of each tissue layer. A univariate analysis comparing the initial shear moduli of the three layers indicates that the muscularis (5.69±4.06 kPa) is the stiffest followed by the submucosa (3.04±3.32 kPa) and the mucosa (0.56±0.28 kPa). The muscularis is found to be strongly distinguishable from the mucosa tissue in the cardiac and fundic region based on a multivariate discriminant analysis. The cardiac muscularis is observed to be stiffer than the fundic muscularis tissue (shear moduli of 7.96±3.82 kPa vs. 3.42±2.96 kPa), more anisotropic (anisotropic parameter of 2.21±0.77 vs. 1.41±0.38), and strongly distinguishable from its fundic counterpart. Finally, a univariate comparison of the in vivo and ex vivo initial shear moduli for each layer shows that the muscularis and submucosa tissues are softer while in vivo, but the mucosa tissue is stiffer while in vivo. The mechanical properties highlight the inhomogeneity and anisotropy of multilayer stomach tissue.
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Affiliation(s)
- Saurabh Dargar
- Center for Modeling, Simulation and Imaging in Medicine (CeMSIM), Rensselaer Polytechnic Institute, Troy, NY, USA; Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Uwe Kruger
- Center for Modeling, Simulation and Imaging in Medicine (CeMSIM), Rensselaer Polytechnic Institute, Troy, NY, USA; Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Suvranu De
- Center for Modeling, Simulation and Imaging in Medicine (CeMSIM), Rensselaer Polytechnic Institute, Troy, NY, USA; Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA; Department of Mechanical, Aerospace, and Nuclear Engineering, , Rensselaer Polytechnic Institute, Troy, NY, USA
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21
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Zhao J, McMahon B, Fox M, Gregersen H. The esophagiome: integrated anatomical, mechanical, and physiological analysis of the esophago-gastric segment. Ann N Y Acad Sci 2018; 1434:5-20. [DOI: 10.1111/nyas.13869] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 04/27/2018] [Accepted: 05/04/2018] [Indexed: 12/24/2022]
Affiliation(s)
- Jingbo Zhao
- GIOME Academy, Department of Clinical Medicine; Aarhus University; Aarhus Denmark
| | - Barry McMahon
- Trinity Academic Gastroenterology Group; Tallaght Hospital and Trinity College; Dublin Ireland
| | - Mark Fox
- Abdominal Center: Gastroenterology; St. Claraspital Basel Switzerland
- Neurogastroenterology and Motility Research Group; University Hospital Zürich; Zürich Switzerland
| | - Hans Gregersen
- GIOME, Department of Surgery; Prince of Wales Hospital and Chinese University of Hong Kong; Shatin Hong Kong SAR
- California Medical Innovations Institute; San Diego California
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Luc G, Charles G, Gronnier C, Cabau M, Kalisky C, Meulle M, Bareille R, Roques S, Couraud L, Rannou J, Bordenave L, Collet D, Durand M. Decellularized and matured esophageal scaffold for circumferential esophagus replacement: Proof of concept in a pig model. Biomaterials 2018; 175:1-18. [PMID: 29793088 DOI: 10.1016/j.biomaterials.2018.05.023] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 05/09/2018] [Accepted: 05/14/2018] [Indexed: 10/16/2022]
Abstract
Surgical resection of the esophagus requires sacrificing a long portion of it. Its replacement by the demanding gastric pull-up or colonic interposition techniques may be avoided by using short biologic scaffolds composed of decellularized matrix (DM). The aim of this study was to prepare, characterize, and assess the in vivo remodeling of DM and its clinical impact in a preclinical model. A dynamic chemical and enzymatic decellularization protocol of porcine esophagus was set up and optimized. The resulting DM was mechanically and biologically characterized by DNA quantification, histology, and histomorphometry techniques. Then, in vitro and in vivo tests were performed, such as DM recellularization with human or porcine adipose-derived stem cells, or porcine stromal vascular fraction, and maturation in rat omentum. Finally, the DM, matured or not, was implanted as a 5-cm-long esophagus substitute in an esophagectomized pig model. The developed protocol for esophageal DM fulfilled previously established criteria of decellularization and resulted in a scaffold that maintained important biologic components and an ultrastructure consistent with a basement membrane complex. In vivo implantation was compatible with life without major clinical complications. The DM's scaffold in vitro characteristics and in vivo implantation showed a pattern of constructive remodeling mimicking major native esophageal characteristics.
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Affiliation(s)
- Guillaume Luc
- CHU Bordeaux, CIC1401, F-33000, Bordeaux, France; Univ. Bordeaux, F-33000, Bordeaux, France; Inserm, Bioingénierie tissulaire, U1026, F-33000, Bordeaux, France; CHU Bordeaux, Department of Digestive Surgery, F-33000, Bordeaux, France
| | - Guillaume Charles
- CHU Bordeaux, CIC1401, F-33000, Bordeaux, France; Univ. Bordeaux, F-33000, Bordeaux, France
| | - Caroline Gronnier
- Univ. Bordeaux, F-33000, Bordeaux, France; CHU Bordeaux, Department of Digestive Surgery, F-33000, Bordeaux, France
| | - Magali Cabau
- CHU Bordeaux, CIC1401, F-33000, Bordeaux, France; Univ. Bordeaux, F-33000, Bordeaux, France; CHU Bordeaux, Department of Digestive Surgery, F-33000, Bordeaux, France
| | - Charlotte Kalisky
- CHU Bordeaux, CIC1401, F-33000, Bordeaux, France; Univ. Bordeaux, F-33000, Bordeaux, France
| | - Mallory Meulle
- CHU Bordeaux, CIC1401, F-33000, Bordeaux, France; Univ. Bordeaux, F-33000, Bordeaux, France
| | - Reine Bareille
- Univ. Bordeaux, F-33000, Bordeaux, France; Inserm, Bioingénierie tissulaire, U1026, F-33000, Bordeaux, France
| | - Samantha Roques
- CHU Bordeaux, CIC1401, F-33000, Bordeaux, France; Univ. Bordeaux, F-33000, Bordeaux, France
| | - Lionel Couraud
- CHU Bordeaux, CIC1401, F-33000, Bordeaux, France; Univ. Bordeaux, F-33000, Bordeaux, France; LAPVSO, F-31201, Toulouse Cedex 2, France
| | - Johanna Rannou
- CHU Bordeaux, CIC1401, F-33000, Bordeaux, France; Univ. Bordeaux, F-33000, Bordeaux, France
| | - Laurence Bordenave
- CHU Bordeaux, CIC1401, F-33000, Bordeaux, France; Univ. Bordeaux, F-33000, Bordeaux, France; Inserm, Bioingénierie tissulaire, U1026, F-33000, Bordeaux, France
| | - Denis Collet
- CHU Bordeaux, Department of Digestive Surgery, F-33000, Bordeaux, France
| | - Marlène Durand
- CHU Bordeaux, CIC1401, F-33000, Bordeaux, France; Univ. Bordeaux, F-33000, Bordeaux, France; Inserm, Bioingénierie tissulaire, U1026, F-33000, Bordeaux, France.
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23
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Kou W, Pandolfino JE, Kahrilas PJ, Patankar NA. Studies of abnormalities of the lower esophageal sphincter during esophageal emptying based on a fully coupled bolus-esophageal-gastric model. Biomech Model Mechanobiol 2018; 17:1069-1082. [PMID: 29644483 DOI: 10.1007/s10237-018-1014-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 03/20/2018] [Indexed: 01/27/2023]
Abstract
The aim of this work was to develop a fully coupled bolus-esophageal-gastric model based on the immersed boundary-finite element method to study the process of esophageal emptying across the esophagogastric junction (EGJ). The model included an esophageal segment, an ellipsoid-shaped stomach, a bolus, and a simple model of the passive and active sphincteric functions of the lower esophageal sphincter (LES). We conducted three sets of case studies: (1) the effect of a non-relaxing LES; (2) the influence of the tissue anisotropy in the form of asymmetrical right- and left-sided compliance of the LES segment; and (3) the influence of LES and gastric wall stiffness on bulge formation of the distal esophageal wall. We found that a non-relaxing LES caused sustained high wall stress along the LES segment and obstruction of bolus emptying. From the simulations of tissue anisotropy, we found that the weaker side (i.e., more compliant) of the LES segment sustained greater deformation, greater wall shear stress, and a greater high-pressure load during bolus transit. In the third set of studies, we found that a right-sided bulge in the esophageal wall tends to develop during esophageal emptying when LES stiffness was decreased or gastric wall stiffness was increased. Hence, the bulge may be partly due to the asymmetric configuration of the gastric wall with respect to the esophageal tube. Together, the observations from these simulations provide insight into the genesis of epiphrenic diverticula, a complication observed with esophageal motility disorders. Future work, with additional layers of complexity to the model, will delve into the mechanics of gastroesophageal reflux and the effects of hiatus hernia on EGJ function.
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Affiliation(s)
- Wenjun Kou
- Department of Medicine, Feinberg School of Medicine, Northwestern University, 676 North Saint Clair Street, 14th Floor, Chicago, IL, 60611, USA
| | - John E Pandolfino
- Department of Medicine, Feinberg School of Medicine, Northwestern University, 676 North Saint Clair Street, 14th Floor, Chicago, IL, 60611, USA
| | - Peter J Kahrilas
- Department of Medicine, Feinberg School of Medicine, Northwestern University, 676 North Saint Clair Street, 14th Floor, Chicago, IL, 60611, USA
| | - Neelesh A Patankar
- Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.
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Mathieu V, de Loubens C, Thomas C, Panouillé M, Magnin A, Souchon I. An experimental model to investigate the biomechanical determinants of pharyngeal mucosa coating during swallowing. J Biomech 2018; 72:144-151. [PMID: 29559243 DOI: 10.1016/j.jbiomech.2018.03.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 02/23/2018] [Accepted: 03/03/2018] [Indexed: 11/30/2022]
Abstract
The development of innovative experimental approaches is necessary to gain insights in the complex biomechanics of swallowing. In particular, unraveling the mechanisms of formation of the thin film of bolus coating the pharyngeal mucosa after the ingestion of liquid or semi-liquid food products is an important challenge, with implication in dysphagia treatment and sensory perceptions. The aim here is to propose an original experimental model of swallowing (i) to simulate the peristaltic motions driving the bolus from the oral cavity to the esophagus, (ii) to mimic and vary complex physiological variables of the pharyngeal mucosa (lubrication, deformability and velocity) and (iii) to measure the thickness and the composition of the coatings resulting from bolus flow. Three Newtonian glucose solutions were considered as model food boli, through sets of experiments covering different ranges of each physiological parameter mimicked. The properties of the coatings (thickness and dilution in saliva film) were shown to depend significantly on the physical properties of food products considered (viscosity and density), but also on physiological variables such as lubrication by saliva, velocity of the peristaltic wave, and to a lesser extent, the deformability of the pharyngeal mucosa. The biomechanical peristalsis simulator developed here can contribute to unravel the determinants of bolus adhesion on pharyngeal mucosa, necessary both for the design of alternative food products for people affected by swallowing disorders, and for a better understanding of the dynamic mechanisms of aroma perception.
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Affiliation(s)
- Vincent Mathieu
- UMR GMPA, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France.
| | - Clément de Loubens
- UMR GMPA, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France; Univ. Grenoble Alpes, CNRS, Grenoble INP (Institute of Engineering Univ. Grenoble Alpes), LRP, 38000 Grenoble, France
| | - Chloé Thomas
- UMR GMPA, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France
| | - Maud Panouillé
- UMR GMPA, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France
| | - Albert Magnin
- Univ. Grenoble Alpes, CNRS, Grenoble INP (Institute of Engineering Univ. Grenoble Alpes), LRP, 38000 Grenoble, France
| | - Isabelle Souchon
- UMR GMPA, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France
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Petsepe DC, Kourkoulis SK, Papadodima SA, Sokolis DP. Regional and age-dependent residual strains, curvature, and dimensions of the human ureter. Proc Inst Mech Eng H 2017; 232:149-162. [PMID: 29278079 DOI: 10.1177/0954411917750192] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The ureters are retroperitoneal structures controlling urine transport from the kidneys to the bladder. Because of the relative scarcity of data on the biomechanical properties of human ureter and the established importance of knowing these properties for understanding its physiology, we initiated biomechanical studies in cadaveric tissue. Herein, we report definite zero-stress/no-load geometrical characterization at 15 regions along the ureter of human cadavers aged 23-82 years, estimating the opening angle, circumferential residual strains, axial curvature, and dimensional parameters. Opening angle decreased along the proximal 25% of ureter, increased and reached a maximum near the mid-ureter, and then gradually decreased toward the vesicoureteral junction (young: p < 0.05; middle-aged: p < 0.05; old: p > 0.05; males: p < 0.05; females: p < 0.05). Similar were the regional distributions of residual strain at the interface between epithelium-lamina propria and muscle and of internal but not external residual strain. Wall thickness increased steadily with aging ( p < 0.05 at few regions), while ureteral circumference did not ( p > 0.05 at most regions) and opening angle decreased ( p < 0.05 at several regions). Consistent with Fung's stress-growth law, the muscle layer thickened with age unlike the epithelium-lamina propria that thinned ( p < 0.05 at most regions for both thicknesses). Moderate-to-strong direct correlations of residual strain difference (= external - internal) with opening angle, wall thickness, and curvature were found in most ureters. The presented data will provide insight into the biomechanical response of ureter under zero/low-stress conditions and the relationship between ureteral remodeling and aging. Importantly, they may also be used to inform finite element models and computational studies simulating the ureter.
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Affiliation(s)
- Despoina C Petsepe
- 1 Department of Mechanics, School of Applied Mathematical and Physical Sciences, National Technical University of Athens, Athens, Greece
| | - Stavros K Kourkoulis
- 1 Department of Mechanics, School of Applied Mathematical and Physical Sciences, National Technical University of Athens, Athens, Greece
| | - Stavroula A Papadodima
- 2 Department of Forensic Medicine and Toxicology, Medical School, University of Athens, Athens, Greece
| | - Dimitrios P Sokolis
- 3 Laboratory of Biomechanics, Center of Clinical, Experimental Surgery & Translational Research, Biomedical Research Foundation Academy of Athens, Athens, Greece
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Dargar S, Akyildiz AC, De S. In Situ Mechanical Characterization of Multilayer Soft Tissue Using Ultrasound Imaging. IEEE Trans Biomed Eng 2017; 64:2595-2606. [PMID: 28026748 PMCID: PMC6218640 DOI: 10.1109/tbme.2016.2644651] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In this paper, we report the development of a technique to characterize layer-specific nonlinear material properties of soft tissue in situ with the potential for in vivo testing. A soft tissue elastography robotic arm system comprising of a robotically manipulated 30 MHz high-resolution ultrasound probe, a custom designed compression head, and load cells has been developed to perform compression ultrasound imaging on the target tissue and measure reaction forces. A multilayer finite element model is iteratively optimized to identify the material coefficients of each layer. Validation has been performed using tissue mimicking agar-based phantoms with a low relative error of ∼7% for two-layer phantoms and ∼10% error for three layer phantoms when compared to known ground-truth values obtained using a commercial material testing system. The technique has then been used to successfully determine the in situ layer-specific mechanical properties of intact porcine stomach. The mean C10 and C20 for a second-order reduced polynomial material model were determined for the muscularis (6.41 ± 0.60, 4.29 ± 1.87 kPa), submucosal (5.21 ± 0.57, 3.68 ± 3.01 kPa), and mucosal layers (0.06 ± 0.02, 0.09 ± 0.24 kPa). Such a system can be utilized to perform in vivo mechanical characterization, which is left as future work.
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Affiliation(s)
- Saurabh Dargar
- Biomedical Engineering Department and with the Center for Modeling, Simulation and Imaging in Medicine (CeMSIM) at Rensselaer Polytechnic Institute in Troy, NY, USA.
| | - Ali C. Akyildiz
- Center for Modeling, Simulation and Imaging in Medicine (CeMSIM) at Rensselaer Polytechnic Institute in Troy, NY, USA.
| | - Suvranu De
- CeMSIM; Department of Mechanical, Aerospace and Nuclear Engineering (MANE) at Rensselaer Polytechnic Institute in Troy, NY, USA.
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Sokolis DP. Experimental study and biomechanical characterization for the passive small intestine: Identification of regional differences. J Mech Behav Biomed Mater 2017; 74:93-105. [DOI: 10.1016/j.jmbbm.2017.05.026] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 05/11/2017] [Accepted: 05/19/2017] [Indexed: 12/16/2022]
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Kou W, Griffith BE, Pandolfino JE, Kahrilas PJ, Patankar NA. A continuum mechanics-based musculo-mechanical model for esophageal transport. JOURNAL OF COMPUTATIONAL PHYSICS 2017; 348:433-459. [PMID: 29081541 PMCID: PMC5655876 DOI: 10.1016/j.jcp.2017.07.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
In this work, we extend our previous esophageal transport model using an immersed boundary (IB) method with discrete fiber-based structural model, to one using a continuum mechanics-based model that is approximated based on finite elements (IB-FE). To deal with the leakage of flow when the Lagrangian mesh becomes coarser than the fluid mesh, we employ adaptive interaction quadrature points to deal with Lagrangian-Eulerian interaction equations based on a previous work (Griffith and Luo [1]). In particular, we introduce a new anisotropic adaptive interaction quadrature rule. The new rule permits us to vary the interaction quadrature points not only at each time-step and element but also at different orientations per element. This helps to avoid the leakage issue without sacrificing the computational efficiency and accuracy in dealing with the interaction equations. For the material model, we extend our previous fiber-based model to a continuum-based model. We present formulations for general fiber-reinforced material models in the IB-FE framework. The new material model can handle non-linear elasticity and fiber-matrix interactions, and thus permits us to consider more realistic material behavior of biological tissues. To validate our method, we first study a case in which a three-dimensional short tube is dilated. Results on the pressure-displacement relationship and the stress distribution matches very well with those obtained from the implicit FE method. We remark that in our IB-FE case, the three-dimensional tube undergoes a very large deformation and the Lagrangian mesh-size becomes about 6 times of Eulerian mesh-size in the circumferential orientation. To validate the performance of the method in handling fiber-matrix material models, we perform a second study on dilating a long fiber-reinforced tube. Errors are small when we compare numerical solutions with analytical solutions. The technique is then applied to the problem of esophageal transport. We use two fiber-reinforced models for the esophageal tissue: a bi-linear model and an exponential model. We present three cases on esophageal transport that differ in the material model and the muscle fiber architecture. The overall transport features are consistent with those observed from the previous model. We remark that the continuum-based model can handle more realistic and complicated material behavior. This is demonstrated in our third case where a spatially varying fiber architecture is included based on experimental study. We find that this unique muscle fiber architecture could generate a so-called pressure transition zone, which is a luminal pressure pattern that is of clinical interest. This suggests an important role of muscle fiber architecture in esophageal transport.
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Affiliation(s)
| | - Boyce E. Griffith
- Departments of Mathematics and Biomedical Engineering, University
of North Carolina at Chapel Hill, Phillips Hall, Campus Box 3250, Chapel
Hill, North Carolina 27599-3250, USA
| | - John E. Pandolfino
- Department of Medicine, Feinberg School of Medicine, Northwestern
University, 676 North Saint Clair Street, 14th Floor, Chicago, Illinois
60611, USA
| | - Peter J. Kahrilas
- Department of Medicine, Feinberg School of Medicine, Northwestern
University, 676 North Saint Clair Street, 14th Floor, Chicago, Illinois
60611, USA
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Peirlinck M, Debusschere N, Iannaccone F, Siersema PD, Verhegghe B, Segers P, De Beule M. An in silico biomechanical analysis of the stent–esophagus interaction. Biomech Model Mechanobiol 2017; 17:111-131. [DOI: 10.1007/s10237-017-0948-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 08/03/2017] [Indexed: 12/15/2022]
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Kou W, Pandolfino JE, Kahrilas PJ, Patankar NA. Simulation studies of the role of esophageal mucosa in bolus transport. Biomech Model Mechanobiol 2017; 16:1001-1009. [PMID: 28050744 DOI: 10.1007/s10237-016-0867-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 12/19/2016] [Indexed: 10/20/2022]
Abstract
Based on a fully coupled computational model for esophageal transport, we analyzed the role of the mucosa (including the submucosa) in esophageal bolus transport and how bolus transport is affected by mucosal stiffness. Two groups of studies were conducted using a computational model. In the first group, a base case that represents normal esophageal transport and two hypothetical cases were simulated: (1) esophageal mucosa replaced by muscle and (2) esophagus without mucosa. For the base case, the geometric configuration of the esophageal wall was examined and the mechanical role of mucosa was analyzed. For the hypothetical cases, the pressure field and transport features were examined. In the second group of studies, cases with mucosa of varying stiffness were simulated. Overall transport characteristics were examined, and both pressure and geometry were analyzed. Results show that a compliant mucosa helped accommodate the incoming bolus and lubricate the moving bolus. Bolus transport was marginally achieved without mucosa or with mucosa replaced by muscle. A stiff mucosa greatly impaired bolus transport due to the lowered esophageal distensibility and increased luminal pressure. We conclude that mucosa is essential for normal esophageal transport function. Mechanically stiffened mucosa reduces the distensibility of the esophagus by obstructing luminal opening and bolus transport. Mucosal stiffening may be relevant in diseases characterized by reduced esophageal distensibility, elevated intrabolus pressure, and/or hypertensive muscle contraction such as eosinophilic esophagitis and jackhammer esophagus.
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Affiliation(s)
- Wenjun Kou
- Theoretical and Applied Mechanics, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - John E Pandolfino
- Department of Medicine, Feinberg School of Medicine, Northwestern University, 676 North Saint Clair Street, 14th Floor, Chicago, IL, 60611, USA
| | - Peter J Kahrilas
- Department of Medicine, Feinberg School of Medicine, Northwestern University, 676 North Saint Clair Street, 14th Floor, Chicago, IL, 60611, USA
| | - Neelesh A Patankar
- Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.
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31
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Sokolis DP, Petsepe DC, Papadodima SA, Kourkoulis SK. Age- and region-related changes in the biomechanical properties and composition of the human ureter. J Biomech 2016; 51:57-64. [PMID: 27939352 DOI: 10.1016/j.jbiomech.2016.11.067] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 11/27/2016] [Accepted: 11/28/2016] [Indexed: 12/17/2022]
Abstract
The ureter has been largely overlooked heretofore in the study of the biomechanics of soft biological tissues, although there has been significant motivation to use its biomechanical properties as inputs to mathematical models of ureteral function. Herein, we used histological analysis for quantification of collagen contents and thickness/area of ureteral layers, with concomitant geometrical analysis of zero-stress and no-load states, and inflation/extension testing to biomechanically characterize with the Fung-type model the ureters from cadavers. The effects of age and gender on the regional distribution of those properties were examined. Tissue properties did not differ (p>0.05) between the left and right ureter. Regional heterogeneity was established that was profoundly age-related but seldom gender-related, based on the following evidence: 1) In younger subjects, the axial stress-circumferential strain curves of upper ureter were shifted to smaller stresses and model parameter a2 representing axial stiffness was smallest (p<0.05), i.e. upper ureter was the least stiff region axially; 2) upper ureter underwent axial stiffening with advanced age, evidenced by the increasing (p<0.05) parameter a2, and the stress-strain curves were uniformly exhibited along the ureter, evidenced by the non-varying (p>0.05) parameters C,a1,a2,anda4; 3) aging raised (p<0.05) the collagen content of upper ureter to favor a near-uniform regional distribution; 4) wall thickness increased with age, unlike the opening angle and residual strains, reflecting the thickening of outer (muscular) vs. inner (mucosal) layers in aged subjects, with significant differences (p<0.05) in some regions; and 5) gender affected little (p>0.05) the opening angle and morphometry of no-load and zero-stress states.
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Affiliation(s)
- Dimitrios P Sokolis
- Laboratory of Biomechanics, Center of Clinical, Experimental Surgery, and Translational Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece.
| | - Despoina C Petsepe
- Department of Mechanics, School of Applied Mathematical and Physical Sciences, National Technical University of Athens, Athens, Greece
| | - Stavroula A Papadodima
- Department of Forensic Medicine and Toxicology, Medical School, University of Athens, Athens, Greece
| | - Stavros K Kourkoulis
- Department of Mechanics, School of Applied Mathematical and Physical Sciences, National Technical University of Athens, Athens, Greece
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32
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Gregersen H, Liao D, Brasseur JG. The Esophagiome: concept, status, and future perspectives. Ann N Y Acad Sci 2016; 1380:6-18. [PMID: 27570939 DOI: 10.1111/nyas.13200] [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: 04/06/2016] [Revised: 07/13/2016] [Accepted: 07/14/2016] [Indexed: 12/23/2022]
Abstract
The term "Esophagiome" is meant to imply a holistic, multiscale treatment of esophageal function from cellular and muscle physiology to the mechanical responses that transport and mix fluid contents. The development and application of multiscale mathematical models of esophageal function are central to the Esophagiome concept. These model elements underlie the development of a "virtual esophagus" modeling framework to characterize and analyze function and disease by quantitatively contrasting normal and pathophysiological function. Functional models incorporate anatomical details with sensory-motor properties and functional responses, especially related to biomechanical functions, such as bolus transport and gastrointestinal fluid mixing. This brief review provides insight into Esophagiome research. Future advanced models can provide predictive evaluations of the therapeutic consequences of surgical and endoscopic treatments and will aim to facilitate clinical diagnostics and treatment.
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Affiliation(s)
- Hans Gregersen
- GIOME, College of Bioengineering, Chongqing University, China. .,GIOME, Department of Surgery, Prince of Wales Hospital, College of Medicine, Chinese University of Hong Kong, Hong Kong SAR.
| | - Donghua Liao
- GIOME Academy, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - James G Brasseur
- Aerospace Engineering Sciences, University of Colorado, Boulder, Colorado
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33
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Aho JM, Qiang B, Wigle DA, Tschumperlin DJ, Urban MW. Nondestructive measurement of esophageal biaxial mechanical properties utilizing sonometry. Phys Med Biol 2016; 61:4781-95. [PMID: 27272663 DOI: 10.1088/0031-9155/61/13/4781] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Malignant esophageal pathology typically requires resection of the esophagus and reconstruction to restore foregut continuity. Reconstruction options are limited and morbid. The esophagus represents a useful target for tissue engineering strategies based on relative simplicity in comparison to other organs. The ideal tissue engineered conduit would have sufficient and ideally matched mechanical tolerances to native esophageal tissue. Current methods for mechanical testing of esophageal tissues both in vivo and ex vivo are typically destructive, alter tissue conformation, ignore anisotropy, or are not able to be performed in fluid media. The aim of this study was to investigate biomechanical properties of swine esophageal tissues through nondestructive testing utilizing sonometry ex vivo. This method allows for biomechanical determination of tissue properties, particularly longitudinal and circumferential moduli and strain energy functions. The relative contribution of mucosal-submucosal layers and muscular layers are compared to composite esophagi. Swine thoracic esophageal tissues (n = 15) were tested by pressure loading using a continuous pressure pump system to generate stress. Preconditioning of tissue was performed by pressure loading with the pump system and pre-straining the tissue to in vivo length before data was recorded. Sonometry using piezocrystals was utilized to determine longitudinal and circumferential strain on five composite esophagi. Similarly, five mucosa-submucosal and five muscular layers from thoracic esophagi were tested independently. This work on esophageal tissues is consistent with reported uniaxial and biaxial mechanical testing and reported results using strain energy theory and also provides high resolution displacements, preserves native architectural structure and allows assessment of biomechanical properties in fluid media. This method may be of use to characterize mechanical properties of tissue engineered esophageal constructs.
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Affiliation(s)
- Johnathon M Aho
- Division of General Thoracic Surgery, Department of Surgery, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA. Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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Brooks RJ, Looi T, Drake J. Prediction of mechanical behaviour from histology in thin collagenous tissues. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2015:4845-8. [PMID: 26737378 DOI: 10.1109/embc.2015.7319478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A method of generating a rough, robust estimate of tensile modulus, elongation at break, and tear out of tissue from histology for the purpose of accelerating medical device and simulator design is presented. The known properties of the individual structural components of tissue are utilized by organizing these components according to existing histological data. This method was able to predict the elastic modulus of esophageal tissue by layer and direction with accuracy close to the standard deviation of the tissue properties, to provide a robust upper limit on tear out force for small (< 0.2mm or 3-0) sutures or clips, and predict force distribution between the layers during tear out.
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Kou W, Bhalla APS, Griffith BE, Pandolfino JE, Kahrilas PJ, Patankar NA. A fully resolved active musculo-mechanical model for esophageal transport. JOURNAL OF COMPUTATIONAL PHYSICS 2015; 298:446-465. [PMID: 26190859 PMCID: PMC4503224 DOI: 10.1016/j.jcp.2015.05.049] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Esophageal transport is a physiological process that mechanically transports an ingested food bolus from the pharynx to the stomach via the esophagus, a multilayered muscular tube. This process involves interactions between the bolus, the esophagus, and the neurally coordinated activation of the esophageal muscles. In this work, we use an immersed boundary (IB) approach to simulate peristaltic transport in the esophagus. The bolus is treated as a viscous fluid that is actively transported by the muscular esophagus, and the esophagus is modeled as an actively contracting, fiber-reinforced tube. Before considering the full model of the esophagus, however, we first consider a standard benchmark problem of flow past a cylinder. Next a simplified version of our model is verified by comparison to an analytic solution to the tube dilation problem. Finally, three different complex models of the multi-layered esophagus, which differ in their activation patterns and the layouts of the mucosal layers, are extensively tested. To our knowledge, these simulations are the first of their kind to incorporate the bolus, the multi-layered esophagus tube, and muscle activation into an integrated model. Consistent with experimental observations, our simulations capture the pressure peak generated by the muscle activation pulse that travels along the bolus tail. These fully resolved simulations provide new insights into roles of the mucosal layers during bolus transport. In addition, the information on pressure and the kinematics of the esophageal wall resulting from the coordination of muscle activation is provided, which may help relate clinical data from manometry and ultrasound images to the underlying esophageal motor function.
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Affiliation(s)
- Wenjun Kou
- Theoretical and Applied Mechanics, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA
| | | | - Boyce E. Griffith
- Department of Mathematics, University of North Carolina at Chapel Hill, Phillips Hall, Campus Box 3250, Chapel Hill, North Carolina 27599-3250, USA
| | - John E. Pandolfino
- Department of Medicine, Feinberg School of Medicine, Northwestern University, 676 North Saint Clair Street, 14th Floor, Chicago, Illinois 60611, USA
| | - Peter J. Kahrilas
- Department of Medicine, Feinberg School of Medicine, Northwestern University, 676 North Saint Clair Street, 14th Floor, Chicago, Illinois 60611, USA
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Kou W, Pandolfino JE, Kahrilas PJ, Patankar NA. Simulation studies of circular muscle contraction, longitudinal muscle shortening, and their coordination in esophageal transport. Am J Physiol Gastrointest Liver Physiol 2015; 309:G238-47. [PMID: 26113296 PMCID: PMC4537927 DOI: 10.1152/ajpgi.00058.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 06/17/2015] [Indexed: 01/31/2023]
Abstract
On the basis of a fully coupled active musculomechanical model for esophageal transport, we aimed to find the roles of circular muscle (CM) contraction and longitudinal muscle (LM) shortening in esophageal transport, and the influence of their coordination. Two groups of studies were conducted using a computational model. In the first group, bolus transport with only CM contraction, only LM shortening, or both was simulated. Overall features and detailed information on pressure and the cross-sectional area (CSA) of mucosal and the two muscle layers were analyzed. In the second group, bolus transport with varying delay in CM contraction or LM shortening was simulated. The effect of delay on esophageal transport was studied. For cases showing abnormal transport, pressure and CSA were further analyzed. CM contraction by itself was sufficient to transport bolus, but LM shortening by itself was not. CM contraction decreased the CSA and the radius of the muscle layer locally, but LM shortening increased the CSA. Synchronized CM contraction and LM shortening led to overlapping of muscle CSA and pressure peaks. Advancing LM shortening adversely influenced bolus transport, whereas lagging LM shortening was irrelevant to bolus transport. In conclusion, CM contraction generates high squeezing pressure, which plays a primary role in esophageal transport. LM shortening increases muscle CSA, which helps to strengthen CM contraction. Advancing LM shortening decreases esophageal distensibility in the bolus region. Lagging LM shortening no longer helps esophageal transport. Synchronized CM contraction and LM shortening seems to be most effective for esophageal transport.
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Affiliation(s)
- Wenjun Kou
- 1Program of Theoretical and Applied Mechanics, Northwestern University, Evanston, Illinois;
| | - John E. Pandolfino
- 2Feinberg School of Medicine, Northwestern University, Chicago, Illinois; and
| | - Peter J. Kahrilas
- 2Feinberg School of Medicine, Northwestern University, Chicago, Illinois; and
| | - Neelesh A. Patankar
- 3Department of Mechanical Engineering, Northwestern University, Evanston, Illinois
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Defagó V, Moyano J, Bernhardt C, Sambuelli G, Cuestas E. Protective effect of early placement of nasogastric tube with solid dilator on tissue damage and stricture formation after caustic esophageal burns in rabbits. J Pediatr Surg 2015; 50:1264-8. [PMID: 25783296 DOI: 10.1016/j.jpedsurg.2014.11.040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 11/19/2014] [Accepted: 11/21/2014] [Indexed: 02/07/2023]
Abstract
BACKGROUND The ingestion of caustic substances remains an important public health issue worldwide. Children represent 80% of the ingestion injury population globally. Accidental alkaline material accounts for most caustic ingestions. There is no conclusive evidence of tissue damage and stricture protection of a nasogastric-tube with a solid dilator in the literature, therefore it was hypothesized that early intraesophageal tube placement does not cause additional histopathologic damage and prevents strictures. METHODS An exploratory study on experimental caustic esophageal burns in a rabbit model was designed. In the treated group a silicone tube was placed immediately after causing the burns, while the untreated group followed the natural course of the burn. On the twenty-secondday, an esophagectomy was performed on all animals for microscopic (Histopathologic Damage Score and Stenosis Index) and macroscopic analysis. RESULTS Forty animals were randomly divided into two groups. The Histopathologic Damage Score was 3.7±1.1 in the treated group versus 3.9±1.2 in the untreated group (p=.9690). The Stenosis Index was 0.6±0.1 in treated rabbits versus 2.3±0.2 in untreated (p<.0001). CONCLUSION The early placement of an intraesophageal tube with solid dilator prevents stenosis formation and does not produce greater tissue damage.
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Affiliation(s)
- Victor Defagó
- Department of Pediatric Surgery, Faculty of Medical Sciences, National University of Cordoba, Cordoba, Argentina
| | - Jimena Moyano
- Department of Pediatric Surgery, Faculty of Medical Sciences, National University of Cordoba, Cordoba, Argentina
| | - Celina Bernhardt
- Department of Pathology, Faculty of Medicine, Catholic University of Cordoba, Cordoba, Argentina
| | - Gabriela Sambuelli
- Department of Pathology, Faculty of Medicine, Catholic University of Cordoba, Cordoba, Argentina
| | - Eduardo Cuestas
- Health Sciences Research Institute-National University of Cordoba-National Scientific and Technical Research Council (INICSA-UNC-CONICET), Cordoba, Argentina.
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Luc G, Durand M, Collet D, Guillemot F, Bordenave L. Esophageal tissue engineering. Expert Rev Med Devices 2014; 11:225-41. [PMID: 24387697 DOI: 10.1586/17434440.2014.870470] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Esophageal tissue engineering is still in an early state, and ideal methods have not been developed. Since the beginning of the 20th century, advances have been made in the materials that can be used to produce an esophageal substitute. Three approaches to scaffold-based tissue engineering have yielded good results. The first development concerned non-absorbable constructs based on silicone and collagen. The need to remove the silicone tube is the main disadvantage of this material. Polymeric absorbable scaffolds have been used since the 1990s. The main polymeric material used is poly (glycolic) acid combined with collagen. The problem of stenosis remains prevalent in most studies using an absorbable construct. Finally, decellularized scaffolds have been used since 2000. The promises of this new approach are unfulfilled. Indeed, stenosis occurs when the esophageal defect is circumferential regardless of the scaffold materials. Cell supplementation can decrease the rate of stenosis, but the type(s) of cells and their roles have not been defined. Finally, esophageal tissue engineering cannot provide a functional esophageal substitute, and further development is necessary prior to conducting human clinical studies.
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Affiliation(s)
- Guillaume Luc
- Department of Digestive Surgery, University Hospital Haut-Lévêque, Av de Magellan, 33604 Pessac cedex, France
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Multiaxial mechanical response and constitutive modeling of esophageal tissues: Impact on esophageal tissue engineering. Acta Biomater 2013; 9:9379-91. [PMID: 23933485 DOI: 10.1016/j.actbio.2013.07.041] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 07/11/2013] [Accepted: 07/31/2013] [Indexed: 12/23/2022]
Abstract
Congenital defects of the esophagus are relatively frequent, with 1 out of 2500 babies suffering from such a defect. A new method of treatment by implanting tissue engineered esophagi into newborns is currently being developed and tested using ovine esophagi. For the reconstruction of the biological function of native tissues with engineered esophagi, their cellular structure as well as their mechanical properties must be considered. Since very limited mechanical and structural data for the esophagus are available, the aim of this study was to investigate the multiaxial mechanical behavior of the ovine esophagus and the underlying microstructure. Therefore, uniaxial tensile, biaxial tensile and extension-inflation tests on esophagi were performed. The underlying microstructure was examined in stained histological sections through standard optical microscopy techniques. Moreover, the uniaxial ultimate tensile strength and residual deformations of the tissue were determined. Both the mucosa-submucosa and the muscle layers showed nonlinear and anisotropic mechanical behavior during uniaxial, biaxial and inflation testing. Cyclical inflation of the intact esophageal tube caused marked softening of the passive esophagi in the circumferential direction. The rupture strength of the mucosa-submucosa layer was much higher than that of the muscle layer. Overall, the ovine esophagus showed a heterogeneous and anisotropic behavior with different mechanical properties for the individual layers. The intact and layer-specific multiaxial properties were characterized using a well-known three-dimensional microstructurally based strain-energy function. This novel and complete set of data serves the basis for a better understanding of tissue remodeling in diseased esophagi and can be used to perform computer simulations of surgical interventions or medical-device applications.
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Sokolis DP. Structurally-motivated characterization of the passive pseudo-elastic response of esophagus and its layers. Comput Biol Med 2013; 43:1273-85. [DOI: 10.1016/j.compbiomed.2013.06.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 06/03/2013] [Accepted: 06/13/2013] [Indexed: 12/16/2022]
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A Microcontinuum Model for Mechanical Properties of Esophageal Tissue: Experimental Methodology and Constitutive Analysis. Ann Biomed Eng 2013; 42:62-72. [DOI: 10.1007/s10439-013-0897-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 08/14/2013] [Indexed: 10/26/2022]
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42
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Sokolis DP, Sassani SG. Microstructure-based constitutive modeling for the large intestine validated by histological observations. J Mech Behav Biomed Mater 2013; 21:149-66. [DOI: 10.1016/j.jmbbm.2013.02.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 02/12/2013] [Accepted: 02/20/2013] [Indexed: 10/27/2022]
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Sokolis DP. Identification and characterisation of regional variations in the material properties of ureter according to microstructure. Comput Methods Biomech Biomed Engin 2013; 17:1653-70. [DOI: 10.1080/10255842.2012.761692] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Sokolis DP. Multiaxial mechanical behaviour of the passive ureteral wall: experimental study and mathematical characterisation. Comput Methods Biomech Biomed Engin 2012; 15:1145-56. [DOI: 10.1080/10255842.2011.581237] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Stavropoulou EA, Dafalias YF, Sokolis DP. Biomechanical behavior and histological organization of the three-layered passive esophagus as a function of topography. Proc Inst Mech Eng H 2012; 226:477-90. [DOI: 10.1177/0954411912444073] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The zero-stress state of the mucosa-submucosa and two muscle esophageal layers has been delineated, but their multi-axial response has not, because muscle dissection may not leave tubular specimens intact for inflation/extension testing. The histomechanical behavior of the three-layered porcine esophagus was investigated in this study, through light microscopic examination and uniaxial tension, with two-dimensional strain measurement in pairs of orthogonally oriented specimens. The two-dimensional Fung-type strain–energy function described suitably the pseudo-elastic tissue response, affording faithful simulations to our data. Differences in the scleroprotein content and configuration were identified as a function of layer, topography, and orientation, substantiating the macromechanical differences found. In view of the failure and optimized material parameters, the mucosa-submucosa was stronger and stiffer than muscle, associating it with a higher collagen content. A notable topographical distribution was apparent, with data for the abdominal region differentiated from that for the cervical region, owing to the existence of inner muscle with a circumferential arrangement and of outer muscle with a longitudinal arrangement in the former region, and of both muscle layers with oblique arrangement in the latter region, with thoracic esophagus being a transition zone. Tissue from the mucosa-submucosa was stronger and stiffer longitudinally, relating with a preferential collagen reinforcement along that axis, but more extensible in the orthogonal axis.
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Affiliation(s)
- Eleni A Stavropoulou
- Laboratory of Biomechanics, Academy of Athens, Greece
- Department of Mechanics, National Technical University of Athens, Greece
| | - Yannis F Dafalias
- Department of Mechanics, National Technical University of Athens, Greece
- Department of Civil and Environmental Engineering, University of California, USA
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Sokolis DP, Orfanidis IK, Peroulis M. Biomechanical testing and material characterization for the rat large intestine: regional dependence of material parameters. Physiol Meas 2011; 32:1969-82. [DOI: 10.1088/0967-3334/32/12/007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Tan J, Chua C, Leong K, Chian K, Leong W, Tan L. Esophageal tissue engineering: An in-depth review on scaffold design. Biotechnol Bioeng 2011; 109:1-15. [DOI: 10.1002/bit.23323] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 08/29/2011] [Accepted: 08/31/2011] [Indexed: 01/29/2023]
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Sokolis DP, Sassani S, Kritharis EP, Tsangaris S. Differential histomechanical response of carotid artery in relation to species and region: mathematical description accounting for elastin and collagen anisotropy. Med Biol Eng Comput 2011; 49:867-79. [PMID: 21626234 DOI: 10.1007/s11517-011-0784-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Accepted: 05/05/2011] [Indexed: 11/24/2022]
Abstract
The selection of a mathematical descriptor for the passive arterial mechanical behavior has been long debated in the literature and customarily constrained by lack of pertinent data on the underlying microstructure. Our objective was to analyze the response of carotid artery subjected to inflation/extension with phenomenological and microstructure-based candidate strain-energy functions (SEFs), according to species (rabbit vs. pig) and region (proximal vs. distal). Histological variations among segments were examined, aiming to explicitly relate them with the differential material response. The Fung-type model could not capture the biphasic response alone. Combining a neo-Hookean with a two-fiber family term alleviated this restraint, but force data were poorly captured, while consideration of low-stress anisotropy via a quadratic term allowed improved simulation of both pressure and force data. The best fitting was achieved with the quadratic and Fung-type or four-fiber family SEF. The latter simulated more closely than the two-fiber family the high-stress response, being structurally justified for all artery types, whereas the quadratic term was justified for transitional and muscular arteries exhibiting notable elastin anisotropy. Diagonally arranged fibers were associated with pericellular medial collagen, and circumferentially and longitudinally arranged fibers with medial and adventitial collagen bundles, evidenced by the significant correlations of SEF parameters with quantitative histology.
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Affiliation(s)
- Dimitrios P Sokolis
- Laboratory of Biomechanics, Center for Experimental Surgery, Foundation of Biomedical Research, Academy of Athens, Athens, Greece.
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Sokolis DP. Strain-energy function and three-dimensional stress distribution in esophageal biomechanics. J Biomech 2010; 43:2753-64. [PMID: 20705294 DOI: 10.1016/j.jbiomech.2010.06.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 06/06/2010] [Accepted: 06/07/2010] [Indexed: 02/07/2023]
Abstract
Knowledge of the transmural stress and stretch fields in esophageal wall is necessary to quantify growth and remodeling, and the response to mechanically based clinical interventions or traumatic injury, but there are currently conflicting reports on this issue and the mechanical properties of intact esophagus have not been rigorously addressed. This paper offers multiaxial data on rabbit esophagus, warranted for proper identification of the 3D mechanical properties. The Fung-type strain-energy function was adopted to model our data for esophagus, taken as a thick-walled (1 or 2-layer) tubular structure subjected to inflation and longitudinal extension. Accurate predictions of the pressure-radius-force data were obtained using the 1-layer model, covering a broad range of extensions; the calculated material parameters indicated that intact wall was equally stiff as mucosa-submucosa, but stiffer than muscle in both principal axes, and tissue was stiffer longitudinally, concurring our histological findings (Stavropoulou et al., Journal of Biomechanics. 42 (2009) 2654-2663). Employing the material parameters of individual layers, with reference to their zero-stress state, a reasonable fit was obtained to the data for intact wall, modeled as a 2-layer tissue. Different from the stress distributions presented hitherto in the esophagus literature, consideration of residual stresses led to less dramatic homogenization of stresses under loading. Comparison of the 1- and 2-layer models of esophagus demonstrated that heterogeneity induced a more uniform distribution of residual stresses in each layer, a discontinuity in circumferential and longitudinal stresses at the interface among layers, and a considerable rise of stresses in mucosa, with a reduction in muscle.
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Affiliation(s)
- Dimitrios P Sokolis
- Laboratory of Biomechanics, Foundation of Biomedical Research, Academy of Athens, Athens, Greece.
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