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Sattari S, Mariano CA, Eskandari M. Pressure-volume mechanics of inflating and deflating intact whole organ porcine lungs. J Biomech 2023; 157:111696. [PMID: 37413822 DOI: 10.1016/j.jbiomech.2023.111696] [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: 10/07/2022] [Revised: 06/14/2023] [Accepted: 06/19/2023] [Indexed: 07/08/2023]
Abstract
Pressure-volume curves of the lung are classical measurements of lung function and are impacted by changes in lung structure due to disease or shifts in air-delivery volume or cycling rate. Diseased and preterm infant lungs have been found to show heterogeneous behavior which is highly frequency dependent. This breathing rate dependency has motivated the exploration of multi-frequency oscillatory ventilators to deliver volume oscillation with optimal frequencies for various portions of the lung to provide more uniform air distribution. The design of these advanced ventilators requires the examination of lung function and mechanics, and an improved understanding of the pressure-volume response of the lung. Therefore, to comprehensively analyze whole lung organ mechanics, we investigate six combinations of varying applied volumes and frequencies using ex-vivo porcine specimens and our custom-designed electromechanical breathing apparatus. Lung responses were evaluated through measurements of inflation and deflation slopes, static compliance, peak pressure and volume, as well as hysteresis, energy loss, and pressure relaxation. Generally, we observed that the lungs were stiffer when subjected to faster breathing rates and lower inflation volumes. The lungs exhibited greater inflation volume dependencies compared to frequency dependencies. This study's reported response of the lung to variations of inflation volume and breathing rate can help the optimization of conventional mechanical ventilators and inform the design of advanced ventilators. Although frequency dependency is found to be minimal in normal porcine lungs, this preliminary study lays a foundation for comparison with pathological lungs, which are known to demonstrate marked rate dependency.
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Affiliation(s)
- Samaneh Sattari
- Department of Mechanical Engineering, University of California at Riverside, Riverside, CA, USA
| | - Crystal A Mariano
- Department of Mechanical Engineering, University of California at Riverside, Riverside, CA, USA
| | - Mona Eskandari
- Department of Mechanical Engineering, University of California at Riverside, Riverside, CA, USA; BREATHE Center, School of Medicine, University of California at Riverside, Riverside, CA, USA; Department of Bioengineering, University of California at Riverside, Riverside, CA, USA.
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2
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Zhang Y, Wang Z, Sun Q, Li Q, Li S, Li X. Dynamic Hydrogels with Viscoelasticity and Tunable Stiffness for the Regulation of Cell Behavior and Fate. MATERIALS (BASEL, SWITZERLAND) 2023; 16:5161. [PMID: 37512435 PMCID: PMC10386333 DOI: 10.3390/ma16145161] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 07/16/2023] [Accepted: 07/19/2023] [Indexed: 07/30/2023]
Abstract
The extracellular matrix (ECM) of natural cells typically exhibits dynamic mechanical properties (viscoelasticity and dynamic stiffness). The viscoelasticity and dynamic stiffness of the ECM play a crucial role in biological processes, such as tissue growth, development, physiology, and disease. Hydrogels with viscoelasticity and dynamic stiffness have recently been used to investigate the regulation of cell behavior and fate. This article first emphasizes the importance of tissue viscoelasticity and dynamic stiffness and provides an overview of characterization techniques at both macro- and microscale. Then, the viscoelastic hydrogels (crosslinked via ion bonding, hydrogen bonding, hydrophobic interactions, and supramolecular interactions) and dynamic stiffness hydrogels (softening, stiffening, and reversible stiffness) with different crosslinking strategies are summarized, along with the significant impact of viscoelasticity and dynamic stiffness on cell spreading, proliferation, migration, and differentiation in two-dimensional (2D) and three-dimensional (3D) cell cultures. Finally, the emerging trends in the development of dynamic mechanical hydrogels are discussed.
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Affiliation(s)
- Yuhang Zhang
- School of Mechanics and Safety Engineering, Zhengzhou University, Zhengzhou 450001, China (Q.L.)
- National Center for International Joint Research of Micro-Nano Moulding Technology, Zhengzhou University, Zhengzhou 450001, China
| | - Zhuofan Wang
- School of Mechanics and Safety Engineering, Zhengzhou University, Zhengzhou 450001, China (Q.L.)
- National Center for International Joint Research of Micro-Nano Moulding Technology, Zhengzhou University, Zhengzhou 450001, China
| | - Qingqing Sun
- School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, China
| | - Qian Li
- School of Mechanics and Safety Engineering, Zhengzhou University, Zhengzhou 450001, China (Q.L.)
- National Center for International Joint Research of Micro-Nano Moulding Technology, Zhengzhou University, Zhengzhou 450001, China
| | - Shaohui Li
- School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, China
| | - Xiaomeng Li
- School of Mechanics and Safety Engineering, Zhengzhou University, Zhengzhou 450001, China (Q.L.)
- National Center for International Joint Research of Micro-Nano Moulding Technology, Zhengzhou University, Zhengzhou 450001, China
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Mariano CA, Sattari S, Ramirez GO, Eskandari M. Effects of tissue degradation by collagenase and elastase on the biaxial mechanics of porcine airways. Respir Res 2023; 24:105. [PMID: 37031200 PMCID: PMC10082978 DOI: 10.1186/s12931-023-02376-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Accepted: 02/22/2023] [Indexed: 04/10/2023] Open
Abstract
BACKGROUND Common respiratory illnesses, such as emphysema and chronic obstructive pulmonary disease, are characterized by connective tissue damage and remodeling. Two major fibers govern the mechanics of airway tissue: elastin enables stretch and permits airway recoil, while collagen prevents overextension with stiffer properties. Collagenase and elastase degradation treatments are common avenues for contrasting the role of collagen and elastin in healthy and diseased states; while previous lung studies of collagen and elastin have analyzed parenchymal strips in animal and human specimens, none have focused on the airways to date. METHODS Specimens were extracted from the proximal and distal airways, namely the trachea, large bronchi, and small bronchi to facilitate evaluations of material heterogeneity, and subjected to biaxial planar loading in the circumferential and axial directions to assess airway anisotropy. Next, samples were subjected to collagenase and elastase enzymatic treatment and tensile tests were repeated. Airway tissue mechanical properties pre- and post-treatment were comprehensively characterized via measures of initial and ultimate moduli, strain transitions, maximum stress, hysteresis, energy loss, and viscoelasticity to gain insights regarding the specialized role of individual connective tissue fibers and network interactions. RESULTS Enzymatic treatment demonstrated an increase in airway tissue compliance throughout loading and resulted in at least a 50% decrease in maximum stress overall. Strain transition values led to significant anisotropic manifestation post-treatment, where circumferential tissues transitioned at higher strains compared to axial counterparts. Hysteresis values and energy loss decreased after enzymatic treatment, where hysteresis reduced by almost half of the untreated value. Anisotropic ratios exhibited axially led stiffness at low strains which transitioned to circumferentially led stiffness when subjected to higher strains. Viscoelastic stress relaxation was found to be greater in the circumferential direction for bronchial airway regions compared to axial counterparts. CONCLUSION Targeted fiber treatment resulted in mechanical alterations across the loading range and interactions between elastin and collagen connective tissue networks was observed. Providing novel mechanical characterization of elastase and collagenase treated airways aids our understanding of individual and interconnected fiber roles, ultimately helping to establish a foundation for constructing constitutive models to represent various states and progressions of pulmonary disease.
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Affiliation(s)
- Crystal A Mariano
- Department of Mechanical Engineering, University of California at Riverside, Riverside, CA, USA
| | - Samaneh Sattari
- Department of Mechanical Engineering, University of California at Riverside, Riverside, CA, USA
| | - Gustavo O Ramirez
- Department of Mechanical Engineering, University of California at Riverside, Riverside, CA, USA
| | - Mona Eskandari
- Department of Mechanical Engineering, University of California at Riverside, Riverside, CA, USA.
- BREATHE Center, School of Medicine, University of California at Riverside, Riverside, CA, USA.
- Department of Bioengineering, University of California at Riverside, Riverside, CA, USA.
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Sattari S, Mariano CA, Kuschner WG, Taheri H, Bates JHT, Eskandari M. Positive- and Negative-Pressure Ventilation Characterized by Local and Global Pulmonary Mechanics. Am J Respir Crit Care Med 2023; 207:577-586. [PMID: 36194677 PMCID: PMC10870900 DOI: 10.1164/rccm.202111-2480oc] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 10/04/2022] [Indexed: 11/16/2022] Open
Abstract
Rationale: There is continued debate regarding the equivalency of positive-pressure ventilation (PPV) and negative-pressure ventilation (NPV). Resolving this question is important because of the different practical ramifications of the two paradigms. Objectives: We sought to investigate the parallel between PPV and NPV and determine whether or not these two paradigms cause identical ventilation profiles by analyzing the local strain mechanics when the global tidal volume (Vt) and inflation pressure was matched. Methods: A custom-designed electromechanical apparatus was used to impose equal global loads and displacements on the same ex vivo healthy porcine lung using PPV and NPV. High-speed high-resolution cameras recorded local lung surface deformations and strains in real time, and differences between PPV and NPV global energetics, viscoelasticity, as well as local tissue distortion were assessed. Measurements and Main Results: During initial inflation, NPV exhibited significantly more bulk pressure-volume compliance than PPV, suggestive of earlier lung recruitment. NPV settings also showed reduced relaxation, hysteresis, and energy loss compared with PPV. Local strain trends were also decreased in NPV, with reduced tissue distortion trends compared with PPV, as revealed through analysis of tissue anisotropy. Conclusions: Apparently, contradictory previous studies are not mutually exclusive. Equivalent changes in transpulmonary pressures in PPV and NPV lead to the same changes in lung volume and pressures, yet local tissue strains differ between PPV and NPV. Although limited to healthy specimens and ex vivo experiments in the absence of a chest cavity, these results may explain previous reports of better oxygenation and less lung injury in NPV.
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Affiliation(s)
| | | | - Ware G. Kuschner
- Medical Service, Veterans Affairs Palo Alto Health Care System, Division of Pulmonary, Allergy & Critical Care Medicine, Stanford University, Stanford, California; and
| | | | - Jason H. T. Bates
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont
| | - Mona Eskandari
- Department of Mechanical Engineering
- BREATHE Center, School of Medicine, and
- Department of Bioengineering, University of California Riverside, Riverside, California
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Biaxial mechanical properties of the bronchial tree: Characterization of elasticity, extensibility, and energetics, including the effect of strain rate and preconditioning. Acta Biomater 2023; 155:410-422. [PMID: 36328122 DOI: 10.1016/j.actbio.2022.10.047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 10/18/2022] [Accepted: 10/21/2022] [Indexed: 11/05/2022]
Abstract
Distal airways commonly obstruct in lung disease and despite their importance, their mechanical properties are vastly underexplored. The lack of bronchial experiments restricts current airway models to either assume rigid structures, or extrapolate the material properties of the trachea to represent the small airways. Furthermore, past works are exclusively limited to uniaxial testing; investigating the multidirectional tensile loads of both the proximal and distal pulmonary airways is long overdue. Here we present comprehensive mechanical and viscoelastic properties of the porcine airway tree, including the trachea, trachealis muscle, large bronchi, and small bronchi, via measures of elasticity, extensibility, and energetics to explore regional and directional dependencies, cross-examining strain rate and preconditioning effects using planar equibiaxial tensile tests for the first time. We find bronchial regions are notably heterogeneous, where the trachea exhibits greater stiffness, energy loss, and preconditioning sensitivity than the smaller airways. Interestingly, the trachealis muscle is similar to the distal bronchi, despite being anatomically located adjacent to the proximal ring. Tissues are anisotropic and axially stiffer under initial loading, losing more energy with greater stress relaxation circumferentially. Strain rate dependency is also noted, where tissues are more energetically efficient at the faster strain rate, likely attributable to the microstructure. Findings highlight assumptions of homogeneity and isotropy are inadequate, and enable the improvement of aerosol flow and dynamic airway deformation computational predictive models. These results provide much needed fundamental material properties for future explorations contrasting healthy versus diseased pulmonary airway mechanics to better understand the relationship between structure and lung function. STATEMENT OF SIGNIFICANCE: We present comprehensive multiaxial mechanical tensile experiments of the proximal and distal airways via measures of maximum stress, initial and ultimate moduli, strain and stress transitions, hysteresis, energy loss, and stress relaxation, and further assess preconditioning and strain rate dependencies to examine the relationship between lung function and structure. The mechanical response of the bronchial tree demonstrates significant anisotropy and heterogeneity, even within the tracheal ring, and emphasizes that contrary to past studies, the behavior of the proximal airways cannot be extended to distal bronchial tree analyses. Establishing these material properties is critical to advancing our understanding of airway function and in developing accurate computational simulations to help diagnose and monitor pulmonary diseases.
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Bao YD, Qu SQ, Qi DB, Wei W. Investigation on puncture mechanical performance of tracheal tissue. J Mech Behav Biomed Mater 2021; 125:104958. [PMID: 34814077 DOI: 10.1016/j.jmbbm.2021.104958] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 10/25/2021] [Accepted: 11/06/2021] [Indexed: 11/29/2022]
Abstract
This paper investigated the mechanical behavior of the contact between the oblique tip puncture needle and the tracheal tissue during pathological examination for the diagnosis of respiratory diseases. By analyzing the force of the oblique tip puncture needle, this paper established a theoretical model of the contact mechanics between the needle and the tracheal tissue. With the material characteristics, needle diameter and puncture angle of trachea tissue as the loading conditions, the biomechanical simulation of piercing process was carried out by using the finite element simulation method, and realistic puncture experiments on isolated porcine tracheal tissue were performed by electronic universal testing machine. The results showed that the puncture needle was mainly subjected to the combined effect of cutting force, clamping force and frictional force on the needle shaft. When the needle diameter was 22G, penetrating the tracheal tissue vertically, the force on the needle was minimal. Meanwhile, it was found that the error between the experimental and theoretical values of the puncture force did not exceed 10%, thus verifying the feasibility of the hypothetical model of the puncture force in the tracheal tissue rupture stage. It provided a theoretical basis for the intervention of surgical instruments and reduced surgical risks.
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Affiliation(s)
- Yu Dong Bao
- Harbin University of Science and Technology, Harbin, China; Key Laboratory of Advanced Manufacturing and Intelligent Technology, Ministry of Education, Harbin, China.
| | - Sheng Qian Qu
- Harbin University of Science and Technology, Harbin, China; Key Laboratory of Advanced Manufacturing and Intelligent Technology, Ministry of Education, Harbin, China
| | - Dong Bo Qi
- Harbin University of Science and Technology, Harbin, China; Key Laboratory of Advanced Manufacturing and Intelligent Technology, Ministry of Education, Harbin, China
| | - Wen Wei
- First Affiliated Hospital of Harbin Medical University, Harbin, China
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Li S, Li Y, Kong M, Zhang C, Geng Y, Sun M, He L, Li S, Liu H. Factors Associated with Age-Related Changes in Non-Smoking Urban Men and Women in China Determined by Low-Dose Computed Tomography Imaging. Med Sci Monit 2021; 27:e931006. [PMID: 34437515 PMCID: PMC8406892 DOI: 10.12659/msm.931006] [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] [Indexed: 11/25/2022] Open
Abstract
Background Respiratory function usually worsens in the elderly with aging. This study aimed to retrospectively investigate tracheal changes caused by “normal aging” through use of low-dose CT (LDCT) in non-smoking asymptomatic urban residents and the related factors influencing tracheal changes. Material/Methods A total of 733 Chinese subjects who underwent LDCT were recruited. The trachea shape, width, and calcification degree of the tracheal wall were measured and compared between males and females and among different age groups. The effects of age, sex, trachea morphology, BMI, BP, GLU, TC, TG, HDL, and LDL on the width and calcification of tracheal wall were analyzed by multiple linear regression. Results Significant sex differences in trachea shape were found, as type II and type I were found mainly in the males and females, respectively. The values of anterior-posterior inner diameter (AP), left-right inner diameter (LR), width, and calcification score of tracheae in the males were higher than that in the females. In both males and females, trachea AP, wall width, and calcification scores increased with age, but this trend was not observed in tracheal LR. Age, sex, and trachea shape had significant effects on the width and calcification scores of tracheal walls, and trachea calcification was one of the factors influencing tracheal wall width. Conclusions Tracheal aging can be evaluated by measuring trachea shape, thickness, and the degree of calcification of the tracheal wall by LDCT, while sex and age should be taken into consideration comprehensively for judging normal trachea aging. In addition, obesity may aggravate trachea aging.
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Affiliation(s)
- Shujing Li
- Department of Radiology, The First Hospital of Hebei Medical University, Shijiazhuang, Hebei, China (mainland)
| | - Yaguang Li
- Department of Radiology, The First Hospital of Hebei Medical University, Shijiazhuang, Hebei, China (mainland)
| | - Meibao Kong
- Department of Radiology, The First Hospital of Hebei Medical University, Shijiazhuang, Hebei, China (mainland)
| | - Chenguang Zhang
- Department of Radiology, The First Hospital of Hebei Medical University, Shijiazhuang, Hebei, China (mainland)
| | - Yulan Geng
- Department of Laboratory, The First Hospital of Hebei Medical University, Shijiazhuang, Hebei, China (mainland)
| | - Mengyue Sun
- Department of Radiology, The First Hospital of Hebei Medical University, Shijiazhuang, Hebei, China (mainland)
| | - Li He
- Department of Radiology, The First Hospital of Hebei Medical University, Shijiazhuang, Hebei, China (mainland)
| | - Shengnan Li
- Department of Radiology, The First Hospital of Hebei Medical University, Shijiazhuang, Hebei, China (mainland)
| | - Huaijun Liu
- Department of Medical Imaging, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, China (mainland)
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Pien N, Palladino S, Copes F, Candiani G, Dubruel P, Van Vlierberghe S, Mantovani D. Tubular bioartificial organs: From physiological requirements to fabrication processes and resulting properties. A critical review. Cells Tissues Organs 2021; 211:420-446. [PMID: 34433163 DOI: 10.1159/000519207] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 01/25/2021] [Indexed: 11/19/2022] Open
Affiliation(s)
- Nele Pien
- Laboratory for Biomaterials and Bioengineering, Canada Research Chair Tier I for the Innovation in Surgery, Department of Min-Met-Materials Engineering & Regenerative Medicine, CHU de Quebec Research Center, Laval University, Quebec City, Québec, Canada
- Polymer Chemistry & Biomaterials Group, Centre of Macromolecular Chemistry, Department of Organic and Macromolecular Chemistry, Ghent University, Ghent, Belgium
| | - Sara Palladino
- Laboratory for Biomaterials and Bioengineering, Canada Research Chair Tier I for the Innovation in Surgery, Department of Min-Met-Materials Engineering & Regenerative Medicine, CHU de Quebec Research Center, Laval University, Quebec City, Québec, Canada
- GenT Lab, Department of Chemistry, Materials and Chemical Engineering "G. Natta", Politecnico di Milano, Milan, Italy
| | - Francesco Copes
- Laboratory for Biomaterials and Bioengineering, Canada Research Chair Tier I for the Innovation in Surgery, Department of Min-Met-Materials Engineering & Regenerative Medicine, CHU de Quebec Research Center, Laval University, Quebec City, Québec, Canada
| | - Gabriele Candiani
- GenT Lab, Department of Chemistry, Materials and Chemical Engineering "G. Natta", Politecnico di Milano, Milan, Italy
| | - Peter Dubruel
- Polymer Chemistry & Biomaterials Group, Centre of Macromolecular Chemistry, Department of Organic and Macromolecular Chemistry, Ghent University, Ghent, Belgium
| | - Sandra Van Vlierberghe
- Polymer Chemistry & Biomaterials Group, Centre of Macromolecular Chemistry, Department of Organic and Macromolecular Chemistry, Ghent University, Ghent, Belgium
| | - Diego Mantovani
- Laboratory for Biomaterials and Bioengineering, Canada Research Chair Tier I for the Innovation in Surgery, Department of Min-Met-Materials Engineering & Regenerative Medicine, CHU de Quebec Research Center, Laval University, Quebec City, Québec, Canada
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Subramaniam DR, Oren L, Willging JP, Gutmark EJ. Evaluating the biomechanical characteristics of cuffed-tracheostomy tubes using finite element analysis. Comput Methods Biomech Biomed Engin 2021; 24:1595-1605. [PMID: 33761806 DOI: 10.1080/10255842.2021.1902511] [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] [Indexed: 10/21/2022]
Abstract
The objective of this study was to perform finite element analysis (FEA) of cuff inflation within an anatomically accurate model of an adult trachea in four different cuffed-tracheostomy tube designs. The leakage quantified by the distance between the cuff and trachea was largest for the Tracoe cuff and smallest for the Portex cuff. The smooth muscle stresses were greatest for the Portex and least for the Distal cuff, respectively. The proposed FEA model offers a promising approach to virtually evaluate the sealing efficacy of cuffed-tracheostomy tubes and the tracheal wall stresses induced by cuff inflation, prior to application.
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Affiliation(s)
| | - Liran Oren
- Department of Otolaryngology-Head and Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - J Paul Willging
- Division of Pediatric Otolaryngology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Ephraim J Gutmark
- Department of Aerospace Engineering and Engineering Mechanics, University of Cincinnati, Cincinnati, OH, USA.,Department of Otolaryngology-Head and Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, OH, USA
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Liu T, Shen M, Li H, Zhang Y, Mu B, Zhao X, Wang Y. Changes and quantitative characterization of hyper-viscoelastic biomechanical properties for young corneal stroma after standard corneal cross-linking treatment with different ultraviolet-A energies. Acta Biomater 2020; 113:438-451. [PMID: 32525050 DOI: 10.1016/j.actbio.2020.06.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 05/30/2020] [Accepted: 06/02/2020] [Indexed: 12/27/2022]
Abstract
Corneal collagen cross-linking (CXL) treatment can restore vision in patients suffering from keratoconus and corneal injury, by improving the mechanical properties of the cornea. The correlation between ultraviolet-A (UVA) irradiant energies of standard CXL (SCXL) and corneal visco-hyperelastic mechanical behavior remains unknown. In this study, SCXL with four different UVA irradiant energy doses (0-5.4 J/cm2) were administered as part of quantitative treatments of corneal stromal lenticules extracted from young myopic patients via small incision lenticule extraction (SMILE) corneal refractive surgery. Double-strip samples with symmetric geometries were cut simultaneously for SCXL treatment and non-treated control. First, 40 pairs of strips were loaded to failure to assess the mechanical parameters of the material. Then, another 40 pairs were tested using a special uniaxial tensile test including quasi-static loading-unloading, instantaneous loading, and stress relaxation, to determine the visco-hyperelastic mechanical behavior. Upon combining the collagen fibril crimping constitutive model with the quasi-linear viscoelastic model, it was observed that with increasing UVA energy dose, the corneal strength and hyperelastic stiffness were significantly enhanced, while the maximum stretch and viscosity of the cornea were significantly reduced. Considering the quantitative analysis of SCXL and the rehabilitation prediction of keratoconus treatment, the results clarify the biomechanical behavior of human corneal stroma in SCXL clinical surgery. STATEMENT OF SIGNIFICANCE: This study quantitatively analyzes the improvement in the biomechanical properties of young central corneal stroma, due to SCXL treatment with different energies. Furthermore, the correlation between the hyper-viscoelastic mechanical parameters and UVA irradiant energy doses of SCXL are clarified. The contribution of this study fills the knowledge gap of the CXL on corneal biomechanics. It can not only clarify this mechanism better but also assist with guiding SCXL surgery for individualized patient corneas.
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Affiliation(s)
- Taiwei Liu
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300350 China; Department of Engineering Mechanics, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Min Shen
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300350 China.
| | - Hongxun Li
- Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin 300020 China; Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300070 China
| | - Yan Zhang
- Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin 300020 China; Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300070 China
| | - Bokun Mu
- Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin 300020 China; Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300070 China
| | - Xinheng Zhao
- Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin 300020 China; Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300070 China
| | - Yan Wang
- Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin 300020 China; Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300070 China
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11
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Characterizing the viscoelasticity of extra- and intra-parenchymal lung bronchi. J Mech Behav Biomed Mater 2020; 110:103824. [PMID: 32957174 DOI: 10.1016/j.jmbbm.2020.103824] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 04/14/2020] [Accepted: 04/20/2020] [Indexed: 11/21/2022]
Abstract
Pulmonary disease is known to cause remodeling of tissue structure, resulting in altered viscoelastic properties; yet the foundation for understanding this phenomenon is still nascent and will enable scientific insights regarding lung functionality. In order to characterize the viscoelastic response of pulmonary airways, uniaxial tensile experiments are conducted on porcine extra- and intra-parenchymal bronchial regions, measuring both axially and circumferentially oriented tissue. Anisotropic and heterogeneous effects on preconditioning and hysteresis are substantial, linking to energy dissipation expectancies. Stress relaxation is rheologically modeled using several classical configurations of discrete spring and dashpot elements; among them, Standard Linear Solid (SLS) and Maxwell-Weichart exhibit better fit performance. Enhanced fractional order derivative SLS (FSLS) model is also evaluated through use of a hybrid spring-pot of order α. FSLS outperforms the conventional models, demonstrating superior representation of the stress-relaxation curve's initial value and non-linear asymptotic decent. FSLS parameters exhibit notable orientation- and region-specific values, trending with observed tissue structural constituents, such as glycosaminoglycan and collagen. To the best of our knowledge, this work is the first to characterize proximal and distal bronchial energy efficiency and contextualize tissue biochemical composition in view of experimental measures and viscoelastic trends. Results provide a foundation for future investigations, particularly for understanding the role of viscoelasticity in diseased states.
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Ramazanilar M, Mojra A. Characterization of breast tissue permeability for detection of vascular breast tumors: An in vitro study. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2019; 107:110222. [PMID: 31761188 DOI: 10.1016/j.msec.2019.110222] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 09/14/2019] [Accepted: 09/17/2019] [Indexed: 01/20/2023]
Abstract
The biological tissue could be considered as a porous matrix filled with the interstitial fluid. The tumoral tissue has a different permeability from the healthy tissue. With regard to this knowledge, the main objective of the present study is to study the tissue permeability as a diagnostic parameter for the detection of breast cancer. To this end, the healthy and the cancerous specimens of the breast tissue are taken from 17 female cases. All cancerous tumors are in the vascular phase of the growth. The samples undergo a uniaxial compression test by a robotic system while the strain rate is set to remain unchanged. Using the stress and the strain rate data, the strain-dependent permeability is determined, which is an exponential function of the strain level. The permeability function is identified by the initial permeability at the zero compressive strain and a material constant. Results show that the initial permeability of the healthy breast tissue is significantly different from the corresponding value for the cancerous tissue. For all cancerous samples, the permeability is less than the healthy tissue samples; as 40-70% reduction in the initial permeability is observed compared to the healthy breast tissue. The evaluation of the permeability between the healthy and the cancerous specimens is accompanied by the biopsy reports and observing structural images of the specimens using environmental scanning electron microscope. Based on the results, the permeability is suggested to have a diagnostic application for the detection of vascular breast tumors.
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Affiliation(s)
- M Ramazanilar
- Department of Mechanical Engineering, K. N. Toosi University of Technology, 15 Pardis St., Tehran, 1991943344, Iran.
| | - A Mojra
- Department of Mechanical Engineering, K. N. Toosi University of Technology, 15 Pardis St., Tehran, 1991943344, Iran.
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Almouemen N, Kelly HM, O'Leary C. Tissue Engineering: Understanding the Role of Biomaterials and Biophysical Forces on Cell Functionality Through Computational and Structural Biotechnology Analytical Methods. Comput Struct Biotechnol J 2019; 17:591-598. [PMID: 31080565 PMCID: PMC6502738 DOI: 10.1016/j.csbj.2019.04.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 03/26/2019] [Accepted: 04/13/2019] [Indexed: 12/13/2022] Open
Abstract
Within the past 25 years, tissue engineering (TE) has grown enormously as a science and as an industry. Although classically concerned with the recapitulation of tissue and organ formation in our body for regenerative medicine, the evolution of TE research is intertwined with progress in other fields through the examination of cell function and behaviour in isolated biomimetic microenvironments. As such, TE applications now extend beyond the field of tissue regeneration research, operating as a platform for modifiable, physiologically-representative in vitro models with the potential to improve the translation of novel therapeutics into the clinic through a more informed understanding of the relevant molecular biology, structural biology, anatomy, and physiology. By virtue of their biomimicry, TE constructs incorporate features of extracellular macrostructure, molecular adhesive moieties, and biomechanical properties, converging with computational and structural biotechnology advances. Accordingly, this mini-review serves to contextualise TE for the computational and structural biotechnology reader and provides an outlook on how the disciplines overlap with respect to relevant advanced analytical applications.
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Affiliation(s)
- Nour Almouemen
- School of Pharmacy, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland
- Tissue Engineering Research Group, Dept. of Anatomy, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland
- Advanced Materials and Bioengineering Research (AMBER) Centre, Royal College of Surgeons in Ireland and Trinity College Dublin, Dublin 2, Ireland
| | - Helena M. Kelly
- School of Pharmacy, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland
- Tissue Engineering Research Group, Dept. of Anatomy, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland
| | - Cian O'Leary
- School of Pharmacy, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland
- Tissue Engineering Research Group, Dept. of Anatomy, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland
- Advanced Materials and Bioengineering Research (AMBER) Centre, Royal College of Surgeons in Ireland and Trinity College Dublin, Dublin 2, Ireland
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Eskandari M, Arvayo AL, Levenston ME. Mechanical properties of the airway tree: heterogeneous and anisotropic pseudoelastic and viscoelastic tissue responses. J Appl Physiol (1985) 2018; 125:878-888. [PMID: 29745796 DOI: 10.1152/japplphysiol.00090.2018] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Airway obstruction and pulmonary mechanics remain understudied despite lung disease being the third cause of death in the United States. Lack of relevant data has led computational pulmonary models to infer mechanical properties from available material data for the trachea. Additionally, the time-dependent, viscoelastic behaviors of airways have been largely overlooked, despite their potential physiological relevance and utility as metrics of tissue remodeling and disease progression. Here, we address the clear need for airway-specific material characterization to inform biophysical studies of the bronchial tree. Specimens from three airway levels (trachea, large bronchi, and small bronchi) and two orientations (axial and circumferential) were prepared from five fresh pig lungs. Uniaxial tensile tests revealed substantial heterogeneity and anisotropy. Overall, the linear pseudoelastic modulus was significantly higher axially than circumferentially (30.5 ± 3.1 vs. 8.4 ± 1.1 kPa) and significantly higher among circumferential samples for small bronchi than for the trachea and large bronchi (12.5 ± 1.9 vs. 6.0 ± 0.6 and 6.6 ± 0.9 kPa). Circumferential samples exhibited greater percent stress relaxation over 300 s than their axial counterparts (38.0 ± 1.4 vs. 23.1 ± 1.5%). Axial and circumferential trachea samples displayed greater percent stress relaxation (26.4 ± 1.6 and 42.5 ± 1.7%) than corresponding large and small bronchi. This ex vivo pseudoelastic and viscoelastic characterization reveals novel anisotropic and heterogeneous behaviors and equips us to construct airway-specific constitutive relations. Our results establish necessary fundamentals for airway mechanics, laying the groundwork for future studies to extend to clinical questions surrounding lung injury, and further directly enables computational tools for lung disease obstruction predictions. NEW & NOTEWORTHY Understanding the mechanics of the lung is necessary for investigating disease progression. Trachea mechanics comprises the vast majority of ex vivo airway tissue characterization despite distal airways being the site of disease manifestation and occlusion. Furthermore, viscoelastic studies are scarce, whereas time-dependent behaviors could be potential physiological metrics of tissue remodeling. In this study, the critical need for airway-specific material properties is addressed, reporting bronchial tree anisotropic and heterogeneous material properties.
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Affiliation(s)
- Mona Eskandari
- Department of Mechanical Engineering, University of California at Riverside , Riverside, California.,Department of Mechanical Engineering, Stanford University , Stanford, California
| | - Alberto L Arvayo
- Department of Mechanical Engineering, Stanford University , Stanford, California
| | - Marc E Levenston
- Department of Mechanical Engineering, Stanford University , Stanford, California.,Department of Bioengineering, Stanford University , Stanford, California
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Charrier EE, Pogoda K, Wells RG, Janmey PA. Control of cell morphology and differentiation by substrates with independently tunable elasticity and viscous dissipation. Nat Commun 2018; 9:449. [PMID: 29386514 PMCID: PMC5792430 DOI: 10.1038/s41467-018-02906-9] [Citation(s) in RCA: 220] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 01/05/2018] [Indexed: 12/21/2022] Open
Abstract
The mechanical properties of extracellular matrices can control the function of cells. Studies of cellular responses to biomimetic soft materials have been largely restricted to hydrogels and elastomers that have stiffness values independent of time and extent of deformation, so the substrate stiffness can be unambiguously related to its effect on cells. Real tissues, however, often have loss moduli that are 10 to 20% of their elastic moduli and behave as viscoelastic solids. The response of cells to a time-dependent viscous loss is largely uncharacterized because appropriate viscoelastic materials are lacking for quantitative studies. Here we report the synthesis of soft viscoelastic solids in which the elastic and viscous moduli can be independently tuned to produce gels with viscoelastic properties that closely resemble those of soft tissues. Systematic alteration of the hydrogel viscosity demonstrates the time dependence of cellular mechanosensing and the influence of viscous dissipation on cell phenotype.
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Affiliation(s)
- Elisabeth E Charrier
- Institute for Medicine and Engineering, University of Pennsylvania, 3340 Smith Walk, Philadelphia, PA, 19104, USA.
- Division of Gastroenterology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, Philadelphia, PA, 19104, USA.
| | - Katarzyna Pogoda
- Institute for Medicine and Engineering, University of Pennsylvania, 3340 Smith Walk, Philadelphia, PA, 19104, USA
- Institute of Nuclear Physics Polish Academy of Sciences, PL-31342, Krakow, Poland
| | - Rebecca G Wells
- Division of Gastroenterology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, Philadelphia, PA, 19104, USA
| | - Paul A Janmey
- Institute for Medicine and Engineering, University of Pennsylvania, 3340 Smith Walk, Philadelphia, PA, 19104, USA
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Hollister SJ, Hollister MP, Hollister SK. Computational modeling of airway instability and collapse in tracheomalacia. Respir Res 2017; 18:62. [PMID: 28424075 PMCID: PMC5395879 DOI: 10.1186/s12931-017-0540-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 03/28/2017] [Indexed: 11/24/2022] Open
Abstract
Background Tracheomalacia (TM) is a condition of excessive tracheal collapse during exhalation. Both acquired and congenital forms of TM are believed to result from morphological changes in cartilaginous, fibrous and/or smooth muscle tissues reducing airway mechanical properties to a degree that precipitates collapse. However, neither the specific amount of mechanical property reduction nor the malacic segment lengths leading to life threatening airway collapse in TM are known. Furthermore, the specific mechanism of collapse is still debated. Methods Computational nonlinear finite element models were developed to determine the effect of malacic segment length, tracheal diameter, and reduction in tissue nonlinear elastic properties on the risk for and mechanism of airway collapse. Cartilage, fibrous tissue, and smooth muscle nonlinear elastic properties were fit to experimental data from preterm lambs from the literature. These elastic properties were systematically reduced in the model to simulate TM. Results An intriguing finding was that sudden mechanical instability leading to complete airway collapse occurred in airways when even a 1 cm segment of cartilage and fibrous tissue properties had a critical reduction in material properties. In general, increased tracheal diameter, increased malacic segment length coupled with decreased nonlinear anterior cartilage/fibrous tissue nonlinear mechanical properties increased the risk of sudden airway collapse from snap through instability. Conclusion Modeling results support snap through instability as the mechanism for life threatening tracheomalacia specifically when cartilage ring nonlinear properties are reduced to a range between fibrous tissue nonlinear elastic properties (for larger diameter airways > 10 mm) to mucosa properties (for smaller diameter airways < 6 mm). Although reducing posterior tracheal smooth muscle properties to mucosa properties decreased exhalation area, no sudden instability leading to collapse was seen in these models.
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Affiliation(s)
- Scott J Hollister
- Wallace A. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Rm 2102 UA Whitaker Biomedical Engineering Bldg, 303 Ferst Drive, Atlanta, GA, 30332, USA.
| | | | - Sebastian K Hollister
- Department of Biomedical Engineering, The University of Michigan, Ann Arbor, MI, USA
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