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Anssari-Benam A, Saccomandi G. Continuous Softening as a State of Hyperelasticity: Examples of Application to the Softening Behavior of the Brain Tissue. J Biomech Eng 2024; 146:091009. [PMID: 38581377 DOI: 10.1115/1.4065271] [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: 01/12/2024] [Accepted: 04/03/2024] [Indexed: 04/08/2024]
Abstract
The continuous softening behavior of the brain tissue, i.e., the softening in the primary loading path with an increase in deformation, is modeled in this work as a state of hyperelasticity up to the onset of failure. That is, the softening behavior is captured via a core hyperelastic model without the addition of damage variables and/or functions. Examples of the application of the model will be provided to extant datasets of uniaxial tension and simple shear deformations, demonstrating the capability of the model to capture the whole-range deformation of the brain tissue specimens, including their softening behavior. Quantitative and qualitative comparisons with other models within the brain biomechanics literature will also be presented, showing the clear advantages of the current approach. The application of the model is then extended to capturing the rate-dependent softening behavior of the tissue by allowing the parameters of the core hyperelastic model to evolve, i.e., vary, with the deformation rate. It is shown that the model captures the rate-dependent and softening behaviors of the specimens favorably and also predicts the behavior at other rates. These results offer a clear set of advantages in favor of the considered modeling approach here for capturing the quasi-static and rate-dependent mechanical properties of the brain tissue, including its softening behavior, over the existing models in the literature, which at best may purport to capture only a reduced set of the foregoing behaviors, and with ill-posed effects.
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Affiliation(s)
- Afshin Anssari-Benam
- Cardiovascular Engineering Research Lab (CERL), School of Mechanical and Design Engineering, University of Portsmouth, Anglesea Road, Portsmouth PO1 3DJ, UK
| | - Giuseppe Saccomandi
- Dipartimento di Ingegneria, Universita degli studi di Perugia, Via G. Duranti, Perugia 06125, Italy
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LeBar K, Liu W, Chicco AJ, Wang Z. Role of Microtubule Network in the Passive Anisotropic Viscoelasticity of Healthy Right Ventricle. J Biomech Eng 2024; 146:071003. [PMID: 38329431 DOI: 10.1115/1.4064685] [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: 10/19/2023] [Accepted: 01/31/2024] [Indexed: 02/09/2024]
Abstract
Cardiomyocytes are viscoelastic and key determinants of right ventricle (RV) mechanics. Intracellularly, microtubules are found to impact the viscoelasticity of isolated cardiomyocytes or trabeculae; whether they contribute to the tissue-level viscoelasticity is unknown. Our goal was to reveal the role of the microtubule network in the passive anisotropic viscoelasticity of the healthy RV. Equibiaxial stress relaxation tests were conducted in healthy RV free wall (RVFW) under early (6%) and end (15%) diastolic strain levels, and at sub- and physiological stretch rates. The viscoelasticity was assessed at baseline and after the removal of microtubule network. Furthermore, a quasi-linear viscoelastic (QLV) model was applied to delineate the contribution of microtubules to the relaxation behavior of RVFW. After removing the microtubule network, RVFW elasticity and viscosity were reduced at the early diastolic strain level and in both directions. The reduction in elasticity was stronger in the longitudinal direction, whereas the degree of changes in viscosity were equivalent between directions. There was insignificant change in RVFW viscoelasticity at late diastolic strain level. Finally, the modeling showed that the tissue's relaxation strength was reduced by the removal of the microtubule network, but the change was present only at a later time scale. These new findings suggest a critical role of cytoskeleton filaments in RVFW passive mechanics in physiological conditions.
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Affiliation(s)
- Kristen LeBar
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523
| | - Wenqiang Liu
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523; Stanford Cardiovascular Institute, Stanford University, Stanford, CA 80523
| | - Adam J Chicco
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523
| | - Zhijie Wang
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523; School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523
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Anssari-Benam A, Saccomandi G. Modelling the rate-dependent mechanical behaviour of the brain tissue. J Mech Behav Biomed Mater 2024; 153:106502. [PMID: 38522863 DOI: 10.1016/j.jmbbm.2024.106502] [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: 01/25/2024] [Revised: 02/21/2024] [Accepted: 03/08/2024] [Indexed: 03/26/2024]
Abstract
A new modelling approach is employed in this work for application to the rate-dependent mechanical behaviour of the brain tissue, as an incompressible isotropic material. Extant datasets encompassing single- and multi-mode compression, tension and simple shear deformation(s) are considered, across a wide range of deformation rates from quasi-static to rates akin to blast loading conditions, in the order of 1000 s-1 . With a simple functional form and a reduced number of parameters, the model is shown to capture the considered rate-dependent behaviours favourably, including in both single- and multi-mode deformation fits, and over all range of deformation rates. The provided modelling results here are obtained from either first fitting the model to the quasi-static data, or/and predicting the behaviour at a different rate than those used for calibrating the model parameters. Given its simplicity, versatility, predictive capability and accuracy, the application of the utilised modelling framework in this work to the rate-dependent mechanical behaviour of the brain tissue is proposed.
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Affiliation(s)
- Afshin Anssari-Benam
- Cardiovascular Engineering Research Lab (CERL), School of Mechanical and Design Engineering, University of Portsmouth, Anglesea Road, Portsmouth, PO1 3DJ, United Kingdom.
| | - Giuseppe Saccomandi
- Dipartimento di Ingegneria, Universita degli studi di Perugia, Via G. Duranti, Perugia, 06125, Italy
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Roth K, Liu W, LeBar K, Ahern M, Wang Z. Establishment of a Biaxial Testing System for Characterization of Right Ventricle Viscoelasticity Under Physiological Loadings. Cardiovasc Eng Technol 2024:10.1007/s13239-024-00722-5. [PMID: 38468114 DOI: 10.1007/s13239-024-00722-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 02/19/2024] [Indexed: 03/13/2024]
Abstract
PURPOSE Prior studies have indicated an impact of cardiac muscle viscoelasticity on systolic and diastolic functions. However, the studies of ventricular free wall viscoelasticity, particularly for that of right ventricles (RV), are limited. Moreover, investigations on ventricular passive viscoelasticity have been restricted to large animals and there is a lack of data on rodent species. To fill this knowledge gap, this study aims to develop a biaxial tester that induces high-speed physiological deformations to characterize the passive viscoelasticity of rat RVs. METHODS The biaxial testing system was fabricated so that planar deformation of rat ventricle tissues at physiological strain rates was possible. The testing system was validated using isotropic polydimethylsiloxane (PDMS) sheets. Next, viscoelastic measurements were performed in healthy rat RV free walls by equibiaxial cyclic sinusoidal loadings and stress relaxation. RESULTS The biaxial tester's consistency, accuracy, and stability was confirmed from the PDMS samples measurements. Moreover, significant viscoelastic alterations of the RV were found between sub-physiological (0.1 Hz) and physiological frequencies (1-8 Hz). From hysteresis loop analysis, we found as the frequency increased, the elasticity and viscosity were increased in both directions. Interestingly, the ratio of storage energy to dissipated energy (Wd/Ws) remained constant at 0.1-5 Hz. We did not observe marked differences in healthy RV viscoelasticity between longitudinal and circumferential directions. CONCLUSION This work provides a new experimental tool to quantify the passive, biaxial viscoelasticity of ventricle free walls in both small and large animals. The dynamic mechanical tests showed frequency-dependent elastic and viscous behaviors of healthy rat RVs. But the ratio of dissipated energy to stored energy was maintained between frequencies. These findings offer novel baseline information on the passive viscoelasticity of healthy RVs in adult rats.
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Affiliation(s)
- Kellan Roth
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Wenqiang Liu
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA
- Stanford Cardiovascular Institute, Stanford University, Stanford, CA, USA
| | - Kristen LeBar
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Matt Ahern
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Zhijie Wang
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA.
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA.
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Terzano M, Wollner MP, Kainz MP, Rolf-Pissarczyk M, Götzen N, Holzapfel GA. Modelling the anisotropic inelastic response of polymeric scaffolds for in situ tissue engineering applications. J R Soc Interface 2023; 20:20230318. [PMID: 37700713 PMCID: PMC10498354 DOI: 10.1098/rsif.2023.0318] [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: 06/01/2023] [Accepted: 08/18/2023] [Indexed: 09/14/2023] Open
Abstract
In situ tissue engineering offers an innovative solution for replacement valves and grafts in cardiovascular medicine. In this approach, a scaffold, which can be obtained by polymer electrospinning, is implanted into the human body and then infiltrated by cells, eventually replacing the scaffold with native tissue. In silico simulations of the whole process in patient-specific models, including implantation, growth and degradation, are very attractive to study the factors that might influence the end result. In our research, we focused on the mechanical behaviour of the polymeric scaffold and its short-term response. Following a recently proposed constitutive model for the anisotropic inelastic behaviour of fibrous polymeric materials, we present here its numerical implementation in a finite element framework. The numerical model is developed as user material for commercial finite element software. The verification of the implementation is performed for elementary deformations. Furthermore, a parallel-plate test is proposed as a large-scale representative example, and the model is validated by comparison with experiments.
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Affiliation(s)
- Michele Terzano
- Institute of Biomechanics, Graz University of Technology, Graz, Austria
| | | | - Manuel P. Kainz
- Institute of Biomechanics, Graz University of Technology, Graz, Austria
| | | | - Nils Götzen
- 4RealSim Services BV, IJsselstein, The Netherlands
| | - Gerhard A. Holzapfel
- Institute of Biomechanics, Graz University of Technology, Graz, Austria
- Department of Structural Engineering, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
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Role of exosomes in bone and joint disease metabolism, diagnosis, and therapy. Eur J Pharm Sci 2022; 176:106262. [PMID: 35850174 DOI: 10.1016/j.ejps.2022.106262] [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: 05/11/2022] [Revised: 07/12/2022] [Accepted: 07/14/2022] [Indexed: 11/21/2022]
Abstract
Bone and joint diseases are prevalent and often fatal conditions in elderly individuals. Additionally, bone-derived cells may release exosomes that package and distribute a range of active substances, such as proteins, miRNAs, and numerous active factors, thereby facilitating material and information interchange between cells. Exososmes generated from bone may be utilized to manage bone production and resorption balance or even as biological or gene therapy carriers, depending on their properties and composition. In this review, we will discuss the composition, secretion, and uptake theory of exososmes, the role of exososmes in bone metabolism regulation, the pathogenesis and diagnosis of bone and joint diseases, and the application of exososmes in regenerative medicine. The findings will expand our understanding of the potential research and application space regarding exososmes.
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Modelling the rate-dependency of the mechanical behaviour of the aortic heart valve: An experimentally guided theoretical framework. J Mech Behav Biomed Mater 2022; 134:105341. [DOI: 10.1016/j.jmbbm.2022.105341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 04/30/2022] [Accepted: 06/26/2022] [Indexed: 11/19/2022]
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