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Barahona J, Sahli Costabal F, Hurtado DE. Machine learning modeling of lung mechanics: Assessing the variability and propagation of uncertainty in respiratory-system compliance and airway resistance. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2024; 243:107888. [PMID: 37948910 DOI: 10.1016/j.cmpb.2023.107888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 10/12/2023] [Accepted: 10/25/2023] [Indexed: 11/12/2023]
Abstract
BACKGROUND AND OBJECTIVE Traditional assessment of patient response in mechanical ventilation relies on respiratory-system compliance and airway resistance. Clinical evidence has shown high variability in these parameters, highlighting the difficulty of predicting them before the start of ventilation therapy. This motivates the creation of computational models that can connect structural and tissue features with lung mechanics. In this work, we leverage machine learning (ML) techniques to construct predictive lung function models informed by non-linear finite element simulations, and use them to investigate the propagation of uncertainty in the lung mechanical response. METHODS We revisit a continuum poromechanical formulation of the lungs suitable for determining patient response. Based on this framework, we create high-fidelity finite element models of human lungs from medical images. We also develop a low-fidelity model based on an idealized sphere geometry. We then use these models to train and validate three ML architectures: single-fidelity and multi-fidelity Gaussian process regression, and artificial neural networks. We use the best predictive ML model to further study the sensitivity of lung response to variations in tissue structural parameters and boundary conditions via sensitivity analysis and forward uncertainty quantification. Codes are available for download at https://github.com/comp-medicine-uc/ML-lung-mechanics-UQ RESULTS: The low-fidelity model delivers a lung response very close to that predicted by high-fidelity simulations and at a fraction of the computational time. Regarding the trained ML models, the multi-fidelity GP model consistently delivers better accuracy than the single-fidelity GP and neural network models in estimating respiratory-system compliance and resistance (R2∼0.99). In terms of computational efficiency, our ML model delivers a massive speed-up of ∼970,000× with respect to high-fidelity simulations. Regarding lung function, we observed an almost matched and non-linear behavior between specific structural parameters and chest wall stiffness with compliance. Also, we observed a strong modulation of airways resistance with tissue permeability. CONCLUSIONS Our findings unveil the relevance of specific lung tissue parameters and boundary conditions in the respiratory-system response. Furthermore, we highlight the advantages of adopting a multi-fidelity ML approach that combines data from different levels to yield accurate and efficient estimates of clinical mechanical markers. We envision that the methods presented here can open the way to the development of predictive ML models of the lung response that can inform clinical decisions.
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Affiliation(s)
- José Barahona
- Department of Structural and Geotechnical Engineering, School of Engineering, Pontificia Universidad Católica de Chile, Santiago, 7820436, Chile; Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, 7820436, Chile
| | - Francisco Sahli Costabal
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, 7820436, Chile; Department of Mechanical and Metallurgical Engineering, School of Engineering, Pontificia Universidad Católica de Chile, Santiago, 7820436, Chile
| | - Daniel E Hurtado
- Department of Structural and Geotechnical Engineering, School of Engineering, Pontificia Universidad Católica de Chile, Santiago, 7820436, Chile; Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, 7820436, Chile; Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, 02140, USA.
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Galloy AE, Reinhardt JM, Raghavan ML. Role of lung lobar sliding on parenchymal distortion during breathing. J Appl Physiol (1985) 2023; 135:534-541. [PMID: 37439240 PMCID: PMC10538991 DOI: 10.1152/japplphysiol.00631.2022] [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: 10/20/2022] [Revised: 06/14/2023] [Accepted: 07/10/2023] [Indexed: 07/14/2023] Open
Abstract
Sliding between lung lobes along lobar fissures is a poorly understood aspect of lung mechanics. The objective of this study was to test the hypothesis that lobar sliding helps reduce distortion in the lung parenchyma during breathing. Finite element models of left lungs with geometries and boundary conditions derived from medical images of human subjects were developed. Effect of lobar sliding was studied by comparing nonlinear finite elastic contact mechanics simulations that allowed and disallowed lobar sliding. Lung parenchymal distortion during simulated breath-holds and tidal breathing was quantified with the model's spatial mean anisotropic deformation index (ADI), a measure of directional preference in volume change that varies spatially in the lung. Models that allowed lobar sliding had significantly lower mean ADI (i.e., lesser parenchymal distortion) than models that disallowed lobar sliding under simulations of both tidal breathing (5.3% median difference, P = 0.008, n = 8) and lung deformation between breath-holds at total lung capacity and functional residual capacity (3.2% median difference, P = 0.03, n = 6). This effect was most pronounced in the lower lobe where lobar sliding reduced parenchymal distortion with statistical significance, but not in the upper lobe. In addition, more lobar sliding was correlated with greater reduction in distortion between sliding and nonsliding models in our study cohorts (Pearson's correlation coefficient of 0.95 for tidal breathing, 0.87 for breath-holds, and 0.91 for the combined dataset). These findings are consistent with the hypothesis that lung lobar sliding reduces parenchymal distortion during breathing.NEW & NOTEWORTHY The role of lobar sliding in lung mechanics is poorly understood. Delineating this role could help explain how breathing is affected by anatomical differences between subjects such as incomplete and missing lobar fissures. We used computational contact mechanics models of lungs from human subjects to delineate the effect of lobar sliding by comparing simulations that allowed and disallowed sliding. We found evidence consistent with the hypothesis that lung lobar sliding reduces parenchymal distortion during breathing.
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Affiliation(s)
- Adam E Galloy
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa, United States
| | - Joseph M Reinhardt
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa, United States
| | - Madhavan L Raghavan
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa, United States
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Daphalapurkar N, Riglin J, Mohan A, Harris J, Bernardin J. Quasi-dynamic breathing model of the lung incorporating viscoelasticity of the lung tissue. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2023:e3744. [PMID: 37334440 DOI: 10.1002/cnm.3744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 03/21/2023] [Accepted: 06/05/2023] [Indexed: 06/20/2023]
Abstract
We advanced a novel model to calculate viscoelastic lung compliance and airflow resistance in presence of mucus, accounting for the quasi-linear viscoelastic stress-strain response of the parenchyma (alveoli) tissue. We adapted a continuum-based numerical modeling approach for the lung, integrating the fluid mechanics of the airflow within individual generations of the bronchi and alveoli. The model accounts for elasticity of the deformable bronchioles, resistance to airflow due to the presence of mucus within the bronchioles, and subsequent mucus flow. Simulated quasi-dynamic inhalation and expiration cycles were used to characterize the net compliance and resistance of the lung, considering the rheology of the mucus and viscoelastic properties of the parenchyma tissue. The structure and material properties of the lung were identified to have an important contribution to the lung compliance and airflow resistance. The secondary objective of this work was to assess whether a higher frequency and smaller volume of harmonic air flow rate compared to a normal ventilator breathing cycle enhanced mucus outflow. Results predict, lower mucus viscosity and higher excitation frequency of breathing are favorable for the flow of mucus up the bronchi tree, towards the trachea.
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Affiliation(s)
- Nitin Daphalapurkar
- Fluid Dynamics and Solid Mechanics, T-3, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | - Jacob Riglin
- Mechanical and Thermal Engineering, E-1, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | - Arvind Mohan
- Computational Physics and Methods, CCS-2, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | - Jennifer Harris
- Biosecurity and Public Health, B-10, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | - John Bernardin
- Mechanical and Thermal Engineering, E-1, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
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Bhana RH, Magan AB. Lung Mechanics: A Review of Solid Mechanical Elasticity in Lung Parenchyma. JOURNAL OF ELASTICITY 2023; 153:53-117. [PMID: 36619653 PMCID: PMC9808719 DOI: 10.1007/s10659-022-09973-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 12/13/2022] [Indexed: 06/17/2023]
Abstract
The lung is the main organ of the respiratory system. Its purpose is to facilitate gas exchange (breathing). Mechanically, breathing may be described as the cyclic application of stresses acting upon the lung surface. These forces are offset by prominent stress-bearing components of lung tissue. These components result from the mechanical elastic properties of lung parenchyma. Various studies have been dedicated to understanding the macroscopic behaviour of parenchyma. This has been achieved through pressure-volume analysis, numerical methods, the development of constitutive equations or strain-energy functions, finite element methods, image processing and elastography. Constitutive equations can describe the elastic behaviour exhibited by lung parenchyma through the relationship between the macroscopic stress and strain. The research conducted within lung mechanics around the elastic and resistive properties of the lung has allowed scientists to develop new methods and equipment for evaluating and treating pulmonary pathogens. This paper establishes a review of mathematical studies conducted within lung mechanics, centering on the development and implementation of solid mechanics to the understanding of the mechanical properties of the lung. Under the classical theory of elasticity, the lung is said to behave as an isotropic elastic continuum undergoing small deformations. However, the lung has also been known to display heterogeneous anisotropic behaviour associated with large deformations. Therefore, focus is placed on the assumptions and development of the various models, their mechanical influence on lung physiology, and the development of constitutive equations through the classical and non-classical theory of elasticity. Lastly, we also look at lung blast mechanics. No explicit emphasis is placed on lung pathology.
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Affiliation(s)
- R. H. Bhana
- School of Computer Science and Applied Mathematics, University of the Witwatersrand, Johannesburg, Wits, 2050 South Africa
| | - A. B. Magan
- School of Computer Science and Applied Mathematics, University of the Witwatersrand, Johannesburg, Wits, 2050 South Africa
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Avilés-Rojas N, Hurtado DE. Whole-lung finite-element models for mechanical ventilation and respiratory research applications. Front Physiol 2022; 13:984286. [PMID: 36267590 PMCID: PMC9577367 DOI: 10.3389/fphys.2022.984286] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 09/12/2022] [Indexed: 11/30/2022] Open
Abstract
Mechanical ventilation has been a vital treatment for Covid-19 patients with respiratory failure. Lungs assisted with mechanical ventilators present a wide variability in their response that strongly depends on air-tissue interactions, which motivates the creation of simulation tools to enhance the design of ventilatory protocols. In this work, we aim to create anatomical computational models of the lungs that predict clinically-relevant respiratory variables. To this end, we formulate a continuum poromechanical framework that seamlessly accounts for the air-tissue interaction in the lung parenchyma. Based on this formulation, we construct anatomical finite-element models of the human lungs from computed-tomography images. We simulate the 3D response of lungs connected to mechanical ventilation, from which we recover physiological parameters of high clinical relevance. In particular, we provide a framework to estimate respiratory-system compliance and resistance from continuum lung dynamic simulations. We further study our computational framework in the simulation of the supersyringe method to construct pressure-volume curves. In addition, we run these simulations using several state-of-the-art lung tissue models to understand how the choice of constitutive models impacts the whole-organ mechanical response. We show that the proposed lung model predicts physiological variables, such as airway pressure, flow and volume, that capture many distinctive features observed in mechanical ventilation and the supersyringe method. We further conclude that some constitutive lung tissue models may not adequately capture the physiological behavior of lungs, as measured in terms of lung respiratory-system compliance. Our findings constitute a proof of concept that finite-element poromechanical models of the lungs can be predictive of clinically-relevant variables in respiratory medicine.
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Affiliation(s)
- Nibaldo Avilés-Rojas
- Department of Structural and Geotechnical Engineering, School of Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Daniel E. Hurtado
- Department of Structural and Geotechnical Engineering, School of Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- *Correspondence: Daniel E. Hurtado,
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Zitnay RG, Herron MR, Carney KR, Potter S, Emerson LL, Weiss JA, Mendoza MC. Mechanics of lung cancer: A finite element model shows strain amplification during early tumorigenesis. PLoS Comput Biol 2022; 18:e1010153. [PMID: 36279309 PMCID: PMC9632844 DOI: 10.1371/journal.pcbi.1010153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 11/03/2022] [Accepted: 10/06/2022] [Indexed: 11/05/2022] Open
Abstract
Early lung cancer lesions develop within a unique microenvironment that undergoes constant cyclic stretch from respiration. While tumor stiffening is an established driver of tumor progression, the contribution of stress and strain to lung cancer is unknown. We developed tissue scale finite element models of lung tissue to test how early lesions alter respiration-induced strain. We found that an early tumor, represented as alveolar filling, amplified the strain experienced in the adjacent alveolar walls. Tumor stiffening further increased the amplitude of the strain in the adjacent alveolar walls and extended the strain amplification deeper into the normal lung. In contrast, the strain experienced in the tumor proper was less than the applied strain, although regions of amplification appeared at the tumor edge. Measurements of the alveolar wall thickness in clinical and mouse model samples of lung adenocarcinoma (LUAD) showed wall thickening adjacent to the tumors, consistent with cellular response to strain. Modeling alveolar wall thickening by encircling the tumor with thickened walls moved the strain amplification radially outward, to the next adjacent alveolus. Simulating iterative thickening in response to amplified strain produced tracks of thickened walls. We observed such tracks in early-stage clinical samples. The tracks were populated with invading tumor cells, suggesting that strain amplification in very early lung lesions could guide pro-invasive remodeling of the tumor microenvironment. The simulation results and tumor measurements suggest that cells at the edge of a lung tumor and in surrounding alveolar walls experience increased strain during respiration that could promote tumor progression.
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Affiliation(s)
- Rebecca G. Zitnay
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, United States of America
- Huntsman Cancer Institute, Salt Lake City, Utah, United States of America
| | - Michael R. Herron
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, United States of America
| | - Keith R. Carney
- Department of Oncological Sciences, University of Utah, Salt Lake City, Utah, United States of America
| | - Scott Potter
- Huntsman Cancer Institute, Salt Lake City, Utah, United States of America
- Department of Pathology, University of Utah, Salt Lake City, Utah, United States of America
| | - Lyska L. Emerson
- Huntsman Cancer Institute, Salt Lake City, Utah, United States of America
- Department of Pathology, University of Utah, Salt Lake City, Utah, United States of America
| | - Jeffrey A. Weiss
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, United States of America
- Scientific Computing and Imaging Institute, Salt Lake City, Utah, United States of America
| | - Michelle C. Mendoza
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, United States of America
- Huntsman Cancer Institute, Salt Lake City, Utah, United States of America
- Department of Oncological Sciences, University of Utah, Salt Lake City, Utah, United States of America
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7
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Naumann J, Koppe N, Thome UH, Laube M, Zink M. Mechanical properties of the premature lung: From tissue deformation under load to mechanosensitivity of alveolar cells. Front Bioeng Biotechnol 2022; 10:964318. [PMID: 36185437 PMCID: PMC9523442 DOI: 10.3389/fbioe.2022.964318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 08/23/2022] [Indexed: 11/16/2022] Open
Abstract
Many preterm infants require mechanical ventilation as life-saving therapy. However, ventilation-induced overpressure can result in lung diseases. Considering the lung as a viscoelastic material, positive pressure inside the lung results in increased hydrostatic pressure and tissue compression. To elucidate the effect of positive pressure on lung tissue mechanics and cell behavior, we mimic the effect of overpressure by employing an uniaxial load onto fetal and adult rat lungs with different deformation rates. Additionally, tissue expansion during tidal breathing due to a negative intrathoracic pressure was addressed by uniaxial tension. We found a hyperelastic deformation behavior of fetal tissues under compression and tension with a remarkable strain stiffening. In contrast, adult lungs exhibited a similar response only during compression. Young’s moduli were always larger during tension compared to compression, while only during compression a strong deformation-rate dependency was found. In fact, fetal lung tissue under compression showed clear viscoelastic features even for small strains. Thus, we propose that the fetal lung is much more vulnerable during inflation by mechanical ventilation compared to normal inspiration. Electrophysiological experiments with different hydrostatic pressure gradients acting on primary fetal distal lung epithelial cells revealed that the activity of the epithelial sodium channel (ENaC) and the sodium-potassium pump (Na,K-ATPase) dropped during pressures of 30 cmH2O. Thus, pressures used during mechanical ventilation might impair alveolar fluid clearance important for normal lung function.
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Affiliation(s)
- Jonas Naumann
- Research Group Biotechnology and Biomedicine, Peter-Debye-Institute for Soft Matter Physics, Leipzig University, Leipzig, Germany
| | - Nicklas Koppe
- Research Group Biotechnology and Biomedicine, Peter-Debye-Institute for Soft Matter Physics, Leipzig University, Leipzig, Germany
| | - Ulrich H. Thome
- Center for Pediatric Research Leipzig, Department of Pediatrics, Division of Neonatology, Leipzig University, Leipzig, Germany
| | - Mandy Laube
- Center for Pediatric Research Leipzig, Department of Pediatrics, Division of Neonatology, Leipzig University, Leipzig, Germany
| | - Mareike Zink
- Research Group Biotechnology and Biomedicine, Peter-Debye-Institute for Soft Matter Physics, Leipzig University, Leipzig, Germany
- *Correspondence: Mareike Zink,
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8
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Neelakantan S, Xin Y, Gaver DP, Cereda M, Rizi R, Smith BJ, Avazmohammadi R. Computational lung modelling in respiratory medicine. J R Soc Interface 2022; 19:20220062. [PMID: 35673857 PMCID: PMC9174712 DOI: 10.1098/rsif.2022.0062] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Computational modelling of the lungs is an active field of study that integrates computational advances with lung biophysics, biomechanics, physiology and medical imaging to promote individualized diagnosis, prognosis and therapy evaluation in lung diseases. The complex and hierarchical architecture of the lung offers a rich, but also challenging, research area demanding a cross-scale understanding of lung mechanics and advanced computational tools to effectively model lung biomechanics in both health and disease. Various approaches have been proposed to study different aspects of respiration, ranging from compartmental to discrete micromechanical and continuum representations of the lungs. This article reviews several developments in computational lung modelling and how they are integrated with preclinical and clinical data. We begin with a description of lung anatomy and how different tissue components across multiple length scales affect lung mechanics at the organ level. We then review common physiological and imaging data acquisition methods used to inform modelling efforts. Building on these reviews, we next present a selection of model-based paradigms that integrate data acquisitions with modelling to understand, simulate and predict lung dynamics in health and disease. Finally, we highlight possible future directions where computational modelling can improve our understanding of the structure–function relationship in the lung.
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Affiliation(s)
- Sunder Neelakantan
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Yi Xin
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Donald P. Gaver
- Department of Biomedical Engineering, Tulane University, New Orleans, LA, USA
| | - Maurizio Cereda
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Rahim Rizi
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Bradford J. Smith
- Department of Bioengineering, University of Colorado Denver
- Anschutz Medical Campus, Aurora, CO, USA
- Department of Pediatric Pulmonary and Sleep Medicine, School of Medicine, University of Colorado, Aurora, CO, USA
| | - Reza Avazmohammadi
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
- J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, TX, USA
- Department of Cardiovascular Sciences, Houston Methodist Academic Institute, Houston, TX, USA
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Novak C, Ballinger MN, Ghadiali S. Mechanobiology of Pulmonary Diseases: A Review of Engineering Tools to Understand Lung Mechanotransduction. J Biomech Eng 2021; 143:110801. [PMID: 33973005 PMCID: PMC8299813 DOI: 10.1115/1.4051118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 05/01/2021] [Indexed: 12/17/2022]
Abstract
Cells within the lung micro-environment are continuously subjected to dynamic mechanical stimuli which are converted into biochemical signaling events in a process known as mechanotransduction. In pulmonary diseases, the abrogated mechanical conditions modify the homeostatic signaling which influences cellular phenotype and disease progression. The use of in vitro models has significantly expanded our understanding of lung mechanotransduction mechanisms. However, our ability to match complex facets of the lung including three-dimensionality, multicellular interactions, and multiple simultaneous forces is limited and it has proven difficult to replicate and control these factors in vitro. The goal of this review is to (a) outline the anatomy of the pulmonary system and the mechanical stimuli that reside therein, (b) describe how disease impacts the mechanical micro-environment of the lung, and (c) summarize how existing in vitro models have contributed to our current understanding of pulmonary mechanotransduction. We also highlight critical needs in the pulmonary mechanotransduction field with an emphasis on next-generation devices that can simulate the complex mechanical and cellular environment of the lung. This review provides a comprehensive basis for understanding the current state of knowledge in pulmonary mechanotransduction and identifying the areas for future research.
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Affiliation(s)
- Caymen Novak
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, The Davis Heart and Lung Research Institute, The Ohio State University, Wexner Medical Center, 473 West 12th Avenue, Columbus, OH 43210
| | - Megan N. Ballinger
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, The Davis Heart and Lung Research Institute, The Ohio State University, Wexner Medical Center, 473 West 12th Avenue, Columbus, OH 43210
| | - Samir Ghadiali
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, The Davis Heart and Lung Research Institute, The Ohio State University, Wexner Medical Center, 473 West 12th Avenue, Columbus, OH 43210; Department of Biomedical Engineering, The Ohio State University, 2124N Fontana Labs, 140 West 19th Avenue, Columbus, OH 43210
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Ghnatios C, Alfaro I, González D, Chinesta F, Cueto E. Data-Driven GENERIC Modeling of Poroviscoelastic Materials
. ENTROPY 2019. [PMCID: PMC7514510 DOI: 10.3390/e21121165] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Biphasic soft materials are challenging to model by nature. Ongoing efforts are targeting their effective modeling and simulation. This work uses experimental atomic force nanoindentation of thick hydrogels to identify the indentation forces are a function of the indentation depth. Later on, the atomic force microscopy results are used in a GENERIC general equation for non-equilibrium reversible–irreversible coupling (GENERIC) formalism to identify the best model conserving basic thermodynamic laws. The data-driven GENERIC analysis identifies the material behavior with high fidelity for both data fitting and prediction.
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Affiliation(s)
- Chady Ghnatios
- Mechanical Engineering Department, Notre Dame University-Louaizé, Zouk Mosbeh P.O. Box 72, Lebanon
- Correspondence: ; Tel.: +961-3-179672
| | - Iciar Alfaro
- Aragon Institute of Engineering Research, Universidad de Zaragoza, Edificio Betancourt, Maria de Luna, s.n., 50018 Zaragoza, Spain; (I.A.); (E.C.)
| | - David González
- Aragon Institute of Engineering Research, Universidad de Zaragoza, Edificio Betancourt, Maria de Luna, s.n., 50018 Zaragoza, Spain; (I.A.); (E.C.)
| | - Francisco Chinesta
- ESI Chair @ ENSAM Arts et Metiers Institute of Technology, 151 Boulevard de l’Hôpital, F-75013 Paris, France;
| | - Elias Cueto
- Aragon Institute of Engineering Research, Universidad de Zaragoza, Edificio Betancourt, Maria de Luna, s.n., 50018 Zaragoza, Spain; (I.A.); (E.C.)
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Birzle AM, Hobrack SMK, Martin C, Uhlig S, Wall WA. Constituent-specific material behavior of soft biological tissue: experimental quantification and numerical identification for lung parenchyma. Biomech Model Mechanobiol 2019; 18:1383-1400. [PMID: 31053928 DOI: 10.1007/s10237-019-01151-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 04/17/2019] [Indexed: 12/14/2022]
Abstract
In this study, we present a method to experimentally quantify and numerically identify the constituent-specific material behavior of soft biological tissues. This allows the clear identification of the individual contributions of major load-bearing constituents and their interactions in the constitutive law. While the overall approach is applicable for many tissues, here it will be presented for the identification of a sophisticated constituent-specific material model of viable lung parenchyma. This material model will help to better model the effects of various lung diseases that feature altered fiber content in the lungs, such as emphysema or fibrosis. To experimentally quantify the mechanical properties of collagen, elastin, collagen-elastin-fiber interactions, and ground substance, we examined 18 collagenase and elastase treated rat lung parenchymal slices. The mechanical contributions of the collagen and elastin fibers in the living tissue were inferred from uniaxial tension tests comparing the behavior before and after the selective digestion of the respective fibers. In order to also obtain the mechanical influence of the ground substance, we consecutively treated the samples with both proteases. Collagen and elastin fibers are morphologically interconnected. Thus, a mechanical interaction between these fibers appears likely, but has not yet been experimentally verified. In this paper, we propose an experimental method to quantitatively assess the mechanical behavior of these collagen-elastin-fiber interactions. Based on our experiments, we have identified individual material models within a nonlinear continuum mechanics framework for each load-bearing component via an inverse analysis. The proposed constituent-specific material law can be incorporated into computational models of the respiratory system to simulate and even predict the behavior and alteration of the individual constituents and their effect on the whole respiratory system during normal and artificial breathing, in particular in the case of diseases that alter the fibers in the tissue.
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Affiliation(s)
- Anna M Birzle
- Institute for Computational Mechanics, Technical University of Munich, Boltzmannstr. 15, 85748, Garching b. Munich, Germany.
| | - Sophie M K Hobrack
- Institute for Computational Mechanics, Technical University of Munich, Boltzmannstr. 15, 85748, Garching b. Munich, Germany.,Munich University of Applied Sciences, Lothstr. 34, 80335, Munich, Germany
| | - Christian Martin
- Institute of Pharmacology and Toxicology, RWTH Aachen University, Wendlingweg 2, 52074, Aachen, Germany
| | - Stefan Uhlig
- Institute of Pharmacology and Toxicology, RWTH Aachen University, Wendlingweg 2, 52074, Aachen, Germany
| | - Wolfgang A Wall
- Institute for Computational Mechanics, Technical University of Munich, Boltzmannstr. 15, 85748, Garching b. Munich, Germany
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12
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Birzle AM, Wall WA. A viscoelastic nonlinear compressible material model of lung parenchyma - Experiments and numerical identification. J Mech Behav Biomed Mater 2019; 94:164-175. [PMID: 30897504 DOI: 10.1016/j.jmbbm.2019.02.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 02/18/2019] [Accepted: 02/20/2019] [Indexed: 12/17/2022]
Abstract
Characterizing material properties of lung parenchyma is essential in order to describe and predict the mechanical behavior of the lung in health and disease. Hence, we aim to identify the viscoelastic constitutive behavior of viable lung parenchyma with a particular focus on the nonlinear, compressible, and frequency-dependent material properties. To quantify the viscoelastic material behavior of rat lung parenchyma experimentally, we performed uniaxial tension tests with different frequencies, including the whole range of physiological frequencies, in combination with full-field displacement measurements (a total of 120 tests on 30 samples of 5 rats). By means of these experimental measurements, we identified the material parameters of two viscoelastic material models applicable to large three-dimensional deformations, i.e., the standard linear solid model and the model of fractional viscoelasticity. Our aim is to identify one set of material parameters that describes the whole range of physiological frequencies; therefore, we utilized a coupled inverse analysis, which equally incorporates all different tensile tests performed on one sample. The model most suitable for the description of the viscoelastic, nonlinear, and compressible material behavior of viable rat lung parenchyma is the strain energy function [Formula: see text] in combination with the model of fractional viscoelasticity (τ=0.06454s,α=0.5378, and β=1.856). This material model was validated to describe the complex nonlinear and compressible viscoelastic material behavior of lung parenchyma and can be utilized in finite element simulations of the whole range of physiological frequencies. Based on this model, it will be possible to quantify the stresses and strains of lung tissue during spontaneous and artificial breathing more reliable in the future.
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Affiliation(s)
- Anna M Birzle
- Institute for Computational Mechanics, Technical University of Munich, Boltzmannstr. 15, 85747 Garching b. München, Germany.
| | - Wolfgang A Wall
- Institute for Computational Mechanics, Technical University of Munich, Boltzmannstr. 15, 85747 Garching b. München, Germany
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