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Pancheri NM, Ellingson AJ, Marchus CR, Durgesh V, Verhage T, Yensen N, Schiele NR. Lysyl Oxidase Production by Murine C3H10T1/2 Mesenchymal Stem Cells Is Increased by TGFβs and Differentially Modulated by Mechanical Stimuli. Stem Cells Dev 2024; 33:355-364. [PMID: 38770821 DOI: 10.1089/scd.2023.0295] [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] [Indexed: 05/22/2024] Open
Abstract
Tendons are frequently injured and have limited regenerative capacity. This motivates tissue engineering efforts aimed at restoring tendon function through strategies to direct functional tendon formation. Generation of a crosslinked collagen matrix is paramount to forming mechanically functional tendon. However, it is unknown how lysyl oxidase (LOX), the primary mediator of enzymatic collagen crosslinking, is regulated by stem cells. This study investigates how multiple factors previously identified to promote tendon formation and healing (transforming growth factor [TGF]β1 and TGFβ2, mechanical stimuli, and hypoxia-inducible factor [HIF]-1α) regulate LOX production in the murine C3H10T1/2 mesenchymal stem cell (MSC) line. We hypothesized that TGFβ signaling promotes LOX activity in C3H10T1/2 MSCs, which is regulated by both mechanical stimuli and HIF-1α activation. TGFβ1 and TGFβ2 increased LOX levels as a function of concentration and time. Inhibiting the TGFβ type I receptor (TGFβRI) decreased TGFβ2-induced LOX production by C3H10T1/2 MSCs. Low (5 mPa) and high (150 mPa) magnitudes of fluid shear stress were applied to test impacts of mechanical stimuli, but without TGFβ2, loading alone did not alter LOX levels. Low loading (5 mPa) with TGFβ2 increased LOX at 7 days greater than TGFβ2 treatment alone. Neither HIF-1α knockdown (siRNA) nor activation (CoCl2) affected LOX levels. Ultimately, results suggest that TGFβ2 and appropriate loading magnitudes contribute to LOX production by C3H10T1/2 MSCs. Potential application of these findings includes treatment with TGFβ2 and appropriate mechanical stimuli to modulate LOX production by stem cells to ultimately control collagen matrix stiffening and support functional tendon formation.
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Affiliation(s)
- Nicholas M Pancheri
- Department of Chemical & Biological Engineering, University of Idaho, Moscow, Idaho, USA
| | - Allison J Ellingson
- Department of Chemical & Biological Engineering, University of Idaho, Moscow, Idaho, USA
| | - Colin R Marchus
- Department of Chemical & Biological Engineering, University of Idaho, Moscow, Idaho, USA
| | - Vibhav Durgesh
- Department of Mechanical Engineering, University of Idaho, Moscow, Idaho, USA
| | - Tabitha Verhage
- Department of Chemical & Biological Engineering, University of Idaho, Moscow, Idaho, USA
| | - Nicholas Yensen
- Department of Chemical & Biological Engineering, University of Idaho, Moscow, Idaho, USA
| | - Nathan R Schiele
- Department of Chemical & Biological Engineering, University of Idaho, Moscow, Idaho, USA
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Alijani H, Vaughan TJ. Exploring the hierarchical structure of lamellar bone and its impact on fracture behaviour: A computational study using a phase field damage model. J Mech Behav Biomed Mater 2024; 153:106471. [PMID: 38458079 DOI: 10.1016/j.jmbbm.2024.106471] [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: 12/08/2023] [Revised: 02/02/2024] [Accepted: 02/16/2024] [Indexed: 03/10/2024]
Abstract
Bone is a naturally occurring composite material composed of a stiff mineral phase and a compliant organic matrix of collagen and non-collagenous proteins (NCP). While diverse mineral morphologies such as platelets and grains have been documented, the precise role of individual constituents, and their morphology, remains poorly understood. To understand the role of constituent morphology on the fracture behaviour of lamellar bone, a damage based representative volume element (RVE) was developed, which considered various mineral morphologies and mineralised collagen fibril (MCF) configurations. This model framework incorporated a novel phase-field damage model to predict the onset and evolution of damage at mineral-mineral and mineral-MCF interfaces. It was found that platelet-based mineral morphologies had superior mechanical performance over their granular counterparts, owing to their higher load-bearing capacity, resulting from a higher aspect ratio. It was also found that MCFs had a remarkable capacity for energy dissipation under axial loading, with these fibrillar structures acting as barriers to crack propagation, thereby enhancing overall elongation and toughness. Interestingly, the presence of extrafibrillar platelet-based minerals also provided an additional toughening through a similar mechanism, whereby these structures also inhibited crack propagation. These findings demonstrate that the two primary constituent materials of lamellar bone play a key role in its toughening behaviour, with combined effect by both mineral and MCFs to inhibit crack propagation at this scale. These results have provided novel insight into the fracture behaviour of lamellar bone, enhancing our understanding of microstructure-property relationships at the sub-tissue level.
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Affiliation(s)
- Hamid Alijani
- Biomechanics Research Centre (BioMEC), Biomedical Engineering, School of Engineering, College of Science and Engineering, University of Galway, Ireland
| | - Ted J Vaughan
- Biomechanics Research Centre (BioMEC), Biomedical Engineering, School of Engineering, College of Science and Engineering, University of Galway, Ireland.
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Xiao P, Roy A, Wang X. In-silico simulation of nanoindentation on bone using a 2D cohesive finite element model. J Mech Behav Biomed Mater 2024; 151:106403. [PMID: 38237206 DOI: 10.1016/j.jmbbm.2024.106403] [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: 12/22/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 02/03/2024]
Abstract
This study proposed and validated a 2D finite element (FE) model for conducting in-silico simulations of in-situ nanoindentation tests on mineralized collagen fibrils (MCF) and the extrafibrillar matrix (EFM) within human cortical bone. Initially, a multiscale cohesive FE model was developed by adapting a previous model of bone lamellae, encompassing both MCF and EFM. Subsequently, nanoindentation tests were simulated in-silico using this model, and the resulting predictions were compared to AFM nanoindentation test data to verify the model's accuracy. The FE model accurately predicted nanoindentation results under wet conditions, closely aligning with outcomes obtained from AFM nanoindentation tests. Specifically, it successfully mirrored the traction/separation curve, nanoindentation modulus, plastic energy dissipation, and plastic energy ratio obtained from AFM nanoindentation tests. Additionally, this in-silico model demonstrated its ability to capture alterations in nanoindentation properties caused by the removal of bound water, by considering corresponding changes in mechanical properties of the collagen phase and the interfaces among bone constituents. Notably, significant changes in the elastic modulus and plastic energy dissipation were observed in both MCF and EFM compartments of bone, consistent with observations in AFM nanoindentation tests. These findings indicate that the proposed in-silico model effectively captures the influence of ultrastructural changes on bone's mechanical properties at sub-lamellar levels. Presently, no experimental methods exist to conduct parametric studies elucidating the ultrastructural origins of bone tissue fragility. The introduction of this in-silico model presents an invaluable tool to bridge this knowledge gap in the future.
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Affiliation(s)
- Pengwei Xiao
- Department of Mechanical Engineering, University of Texas at San Antonio, USA
| | - Anuradha Roy
- Department of Management Science and Statistics, University of Texas at San Antonio, USA
| | - Xiaodu Wang
- Department of Mechanical Engineering, University of Texas at San Antonio, USA.
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Bhattacharya S, Dubey DK. A multiscale investigation into the role of collagen-hyaluronan interface shear on the mechanical behaviour of collagen fibers in annulus fibrosus - Molecular dynamics-cohesive finite element-based study. J Mech Behav Biomed Mater 2023; 147:106147. [PMID: 37812947 DOI: 10.1016/j.jmbbm.2023.106147] [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: 04/13/2023] [Revised: 06/30/2023] [Accepted: 09/23/2023] [Indexed: 10/11/2023]
Abstract
Multi-directional deformation exhibited by annulus fibrosus (AF) is contributed by chemo-mechanical interactions among its biomolecular constituents' collagen type I (COL-I), collagen type II (COL-II), proteoglycans (aggrecan and hyaluronan) and water. However, the nature and role of such interactions on AF mechanics are unclear. This work employs a molecular dynamics-cohesive finite element-based multiscale approach to investigate role of COL-I-COL-II interchanging distribution and water concentration (WC) variations from outer annulus (OA) to inner annulus (IA) on collagen-hyaluronan (COL-HYL) interface shear, and the mechanisms by which interface shear impacts fibril sliding during collagen fiber deformation. At first, COL-HYL interface atomistic models are constructed by interchanging COL-I with COL-II and increasing COL-II and WC from 0 to 75%, and 65%-75% respectively. Thereafter, a multiscale approach is employed to develop representative volume elements (RVEs) of collagen fibers by incorporating COL-HYL shear as traction-separation behaviour at fibril-hyaluronan contact. Results show that increasing COL-II and WC increases interface stiffness from 0.6 GPa/nm to 1.2 GPa/nm and reduces interface strength from 155 MPa to 58 MPa from OA to IA, contributed by local hydration alterations. A stiffer and weaker interface enhances fibril sliding with increased straining at the contact - thereby contributing to reduction in modulus from 298 MPa to 198 MPa from OA to IA. Such reduction further contributes to softer mechanical response towards IA, as reported by earlier studies. Presented multiscale analysis provides deeper understanding of hierarchical structure-mechanics relationships in AF and can further aid in developing better substitutes for AF repair.
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Affiliation(s)
- Shambo Bhattacharya
- Department of Mechanical Engineering, Indian Institute of Technology Delhi, Haus Khas, New Delhi, 110016, India
| | - Devendra K Dubey
- Department of Mechanical Engineering, Indian Institute of Technology Delhi, Haus Khas, New Delhi, 110016, India.
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Yang F, Das D, Karunakaran K, Genin GM, Thomopoulos S, Chasiotis I. Nonlinear time-dependent mechanical behavior of mammalian collagen fibrils. Acta Biomater 2023; 163:63-77. [PMID: 35259515 PMCID: PMC9441475 DOI: 10.1016/j.actbio.2022.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 02/16/2022] [Accepted: 03/02/2022] [Indexed: 11/01/2022]
Abstract
The viscoelastic mechanical behavior of collagenous tissues has been studied extensively at the macroscale, yet a thorough quantitative understanding of the time-dependent mechanics of the basic building blocks of tissues, the collagen fibrils, is still missing. In order to address this knowledge gap, stress relaxation and creep tests at various stress (5-35 MPa) and strain (5-20%) levels were performed with individual collagen fibrils (average diameter of fully hydrated fibrils: 253 ± 21 nm) in phosphate buffered saline (PBS). The experimental results showed that the time-dependent mechanical behavior of fully hydrated individual collagen fibrils reconstituted from Type I calf skin collagen, is described by strain-dependent stress relaxation and stress-dependent creep functions in both the heel-toe and the linear regimes of deformation in monotonic stress-strain curves. The adaptive quasilinear viscoelastic (QLV) model, originally developed to capture the nonlinear viscoelastic response of collagenous tissues, provided a very good description of the nonlinear stress relaxation and creep behavior of the collagen fibrils. On the other hand, the nonlinear superposition (NSP) model fitted well the creep but not the stress relaxation data. The time constants and rates extracted from the adaptive QLV and the NSP models, respectively, pointed to a faster rate for stress relaxation than creep. This nonlinear viscoelastic behavior of individual collagen fibrils agrees with prior studies of macroscale collagenous tissues, thus demonstrating consistent time-dependent behavior across length scales and tissue hierarchies. STATEMENT OF SIGNIFICANCE: Pure stress relaxation and creep experiments were conducted for the first time with fully hydrated individual collagen fibrils. It is shown that collagen nanofibrils have a nonlinear time-dependent behavior which agrees with prior studies on macroscale collagenous tissues, thus demonstrating consistent time-dependent behavior across length scales and tissue hierarchies. This new insight into the non-linear viscoelastic behavior of the building blocks of mammalian collagenous tissues may serve as the foundation for improved macroscale tissue models that capture the mechanical behavior across length scales.
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Affiliation(s)
- Fan Yang
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Debashish Das
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Kathiresan Karunakaran
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Guy M Genin
- Mechanical Engineering and Materials Science, Washington University, St. Louis, MO 63130, USA
| | - Stavros Thomopoulos
- Orthopedic Surgery, Biomedical Engineering, Columbia University, New York, NY 10032, USA
| | - Ioannis Chasiotis
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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6
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Gasser TC, Miller C, Polzer S, Roy J. A quarter of a century biomechanical rupture risk assessment of abdominal aortic aneurysms. Achievements, clinical relevance, and ongoing developments. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2023; 39:e3587. [PMID: 35347895 DOI: 10.1002/cnm.3587] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 01/28/2022] [Accepted: 03/03/2022] [Indexed: 05/12/2023]
Abstract
Abdominal aortic aneurysm (AAA) disease, the local enlargement of the infrarenal aorta, is a serious condition that causes many deaths, especially in men exceeding 65 years of age. Over the past quarter of a century, computational biomechanical models have been developed towards the assessment of AAA risk of rupture, technology that is now on the verge of being integrated within the clinical decision-making process. The modeling of AAA requires a holistic understanding of the clinical problem, in order to set appropriate modeling assumptions and to draw sound conclusions from the simulation results. In this article we summarize and critically discuss the proposed modeling approaches and report the outcome of clinical validation studies for a number of biomechanics-based rupture risk indices. Whilst most of the aspects concerning computational mechanics have already been settled, it is the exploration of the failure properties of the AAA wall and the acquisition of robust input data for simulations that has the greatest potential for the further improvement of this technology.
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Affiliation(s)
- T Christian Gasser
- Department of Engineering Mechanics, KTH Royal Institute of Technology, Stockholm, Sweden
- Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
| | - Christopher Miller
- Department of Engineering Mechanics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Stanislav Polzer
- Department of Applied Mechanics, VSB-Technical University of Ostrava, Ostrava-Poruba, Czech Republic
| | - Joy Roy
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
- Department of Vascular Surgery, Karolinska University Hospital, Stockholm, Sweden
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Chen S, Arola D, Ricucci D, Bergeron BE, Branton JA, Gu LS, Tay FR. Biomechanical perspectives on dentine cracks and fractures: Implications in their clinical management. J Dent 2023; 130:104424. [PMID: 36657703 DOI: 10.1016/j.jdent.2023.104424] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/09/2023] [Accepted: 01/12/2023] [Indexed: 01/18/2023] Open
Abstract
OBJECTIVES The present review discussed the biomechanical properties of cracks and fractures in crown and root dentine and attempted to explain why cracked teeth and vertical root fractures are so frequent despite the existence of multiple crack toughening mechanisms in dentine. The implications of this knowledge were used to justify how these defects are managed clinically. DATA, SOURCES AND STUDY SELECTION Literature search was conducted on PubMed, Web of Science, and Scopus for a narrative review on fracture mechanics of crown and root dentine as well as the clinical management of cracked teeth and teeth with vertical root fracture. CONCLUSIONS Although dentine is tougher and less brittle than enamel, it's facture toughness is considerably lower than most ductile metals. Because the initiation toughness of dentine is very low, cracks initiate from incipient damage under low stress While crack toughening mechanisms exist that enable dentine to resist crack extension, these mechanisms are often inadequate for protecting dentine from crack propagation that ultimately leads to catastrophic failure. Additional factors such as ageing also reduces the resistance of dentine to crack growth. Because dentine cracks are eventually filled with bacteria biofilms upon exposure to oral fluids, they enable rapid bacteria ingress into the dental pulp via open dentinal tubules. To date, treatment options for cracked teeth are limited. While most teeth with vertical root fracture are recommended for extraction, new strategies have been reported that appeared to achieve short-term success in preserving these teeth. CLINICAL SIGNIFICANCE Current strategies for the management for dentine cracks and fractures are limited and their long-term effectiveness remain uncertain. Understanding the characteristics, toughening mechanism and weakening factors of tooth cracks is helpful in designing better treatment.
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Affiliation(s)
- Sishi Chen
- Hospital of Stomatology, Sun Yat-sen University & Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, PR China
| | - Dwayne Arola
- Department of Materials Science and Engineering, University of Washington, Seattle, WA USA
| | | | - Brian E Bergeron
- Department of Endodontics, The Dental College of Georgia, Augusta University, Augusta, GA, USA
| | - John A Branton
- Department of Endodontics, The Dental College of Georgia, Augusta University, Augusta, GA, USA
| | - Li-Sha Gu
- Hospital of Stomatology, Sun Yat-sen University & Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, PR China.
| | - Franklin R Tay
- Department of Endodontics, The Dental College of Georgia, Augusta University, Augusta, GA, USA.
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8
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Adouni M, Faisal T, Dhaher Y. Effect of Surgical Design Variations on the Knee Contact Behavior during Anterior Cruciate Ligament Reconstruction. J Knee Surg 2023; 36:310-321. [PMID: 34375997 DOI: 10.1055/s-0041-1733879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In this study, we aimed to develop an in-silico synthesis of the effect of critical surgical design parameters on articular contact behavior for a bone-patellar-tendon-bone anterior cruciate ligament reconstruction (ACL-R) surgery. A previously developed finite element model of the knee joint consisting of all relevant soft tissues was employed. The knee model was further updated with additional features to develop the parametric FE model of the biomechanical experiments that depicted the ACL-R surgery. The parametricity was created involving femoral tunnel architecture (orientations and locations) and graft fixation characteristics (pretension and angle of fixation). A global sensitivity analysis based on variance decomposition was used to investigate the contribution of the surgical parameters to the uncertainty in response to the ACL-R joint. Our examinations indicated that the total contact force was primarily influenced by either combined or individual action of the graft pretension and fixation angle, with a modest contribution of the graft insertion sites. The joint contact center and area were affected mainly by the angle of fixation and the tunnel placements. Graft pretension played the dominant role in the maximum contact pressure variability, an observation that has been well-documented in the literature. Interestingly, the joint contact behavior was almost insensitive to the tunnel's coronal and sagittal orientations. Our data provide an evaluation of how the surgical parameters affect the knee joint's contact behavior after ACL-R and may provide additional information to better explain the occurrence of osteoarthritis as an aftermath of such surgery.
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Affiliation(s)
- Malek Adouni
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, Illinois.,Department of Mechanical Engineering, Australian College of Kuwait, Kuwait City, Kuwait
| | - Tanvir Faisal
- Department of Bioengineering, University of Texas Southwest, Dallas, Texas
| | - Yasin Dhaher
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, Illinois.,Department of Mechanical Engineering, University of Louisiana at Lafayette, Louisiana.,Department of Physical Medicine and Rehabilitation, University of Texas Southwest, Dallas, Texas.,Department of Orthopedic Surgery, University of Texas Southwest, Dallas, Texas
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Faisal TR, Adouni M, Dhaher YY. Surrogate modeling of articular cartilage degradation to understand the synergistic role of MMP-1 and MMP-9: a case study. Biomech Model Mechanobiol 2023; 22:43-56. [PMID: 36201069 DOI: 10.1007/s10237-022-01630-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 08/22/2022] [Indexed: 11/26/2022]
Abstract
A characteristic feature of arthritic diseases is cartilage extracellular matrix (ECM) degradation, often orchestrated by the overexpression of matrix metalloproteinases (MMPs) and other proteases. The interplay between fibril level degradation and the tissue-level aggregate response to biomechanical loading was explored in this work by a computational multiscale cartilaginous model. We considered the relative abundance of collagenases (MMP-1) and gelatinases (MMP-9) in surrogate models, where the diffusion (spatial distribution) of these enzymes and the subsequent, co-localized fibrillar damage were spatially randomized with Latin Hypercube Sampling. The computational model was constructed by incorporating the results from prior molecular dynamics simulations (tensile test) of microfibril degradation into a hyper-elastoplastic fibril-reinforced cartilage model. Including MMPs-mediated collagen fibril-level degradation in computational models may help understand the ECM pathomechanics at the tissue level. The mechanics of cartilage tissue and fibril show variations in mechanical integrity depending on the different combinations of MMPs-1 and 9 with a concentration ratio of 1:1, 3:1, and 1:3 in simulated indentation tests. The fibril yield (local failure) was initiated at 20.2 ± 3.0 (%) and at 23.0 ± 2.8 (%) of bulk strain for col 1:gel 3 and col 3: gel 1, respectively. The reduction in failure stress (global response) was 39.8% for col 1:gel 3, 37.5% for col 1:gel 1, and 36.7% for col 3:gel 1 compared with the failure stress of the degradation free tissue. These findings indicate that cartilage's global and local mechanisms of failure largely depend on the relative abundance of the two key enzymes-collagenase (MMP-1) and gelatinase (MMP-9) and the spatial characteristics of diffusion across the layers of the cartilage ECM.
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Affiliation(s)
- Tanvir R Faisal
- Department of Mechanical Engineering, University of Louisiana at Lafayette, Lafayette, LA, 70508, USA.
| | - Malek Adouni
- Department of Mechanical Engineering, Australian College of Kuwait, East Mishref, Kuwait City, P.O. Box 1411, Kuwait
| | - Yasin Y Dhaher
- Department of Physical Medicine and Rehabilitation, University of Texas Southwest, Dallas, TX, USA
- Department of Orthopedic Surgery, University of Texas Southwest, Dallas, TX, USA
- Department of Biomedical Engineering, University of Texas Southwest, Dallas, TX, USA
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Lin AH, Slater CA, Martinez CJ, Eppell SJ, Yu SM, Weiss JA. Collagen fibrils from both positional and energy-storing tendons exhibit increased amounts of denatured collagen when stretched beyond the yield point. Acta Biomater 2023; 155:461-470. [PMID: 36400348 PMCID: PMC9805521 DOI: 10.1016/j.actbio.2022.11.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 11/04/2022] [Accepted: 11/09/2022] [Indexed: 11/17/2022]
Abstract
Collagen molecules are the base structural unit of tendons, which become denatured during mechanical overload. We recently demonstrated that during tendon stretch, collagen denaturation occurs at the yield point of the stress-strain curve in both positional and energy-storing tendons. We were interested in investigating how this load is transferred throughout the collagen hierarchy, and sought to determine the onset of collagen denaturation when collagen fibrils are stretched. Fibrils are one level above the collagen molecule in the collagen hierarchy, allowing more direct probing of the effect of strain on collagen molecules. We isolated collagen fibrils from both positional and energy-storing tendon types and stretched them using a microelectromechanical system device to various levels of strain. We stained the fibrils with fluorescently labeled collagen hybridizing peptides that specifically bind to denatured collagen, and examined whether samples stretched beyond the yield point of the stress-strain curve exhibited increased amounts of denatured collagen. We found that collagen denaturation in collagen fibrils from both tendon types occurs at the yield point. Greater amounts of denatured collagen were found in post-yield positional fibrils than in energy-storing fibrils. This is despite a greater yield strain and yield stress in fibrils from energy-storing tendons compared to positional tendons. Interestingly, the peak modulus of collagen fibrils from both tendon types was the same. These results are likely explained by the greater crosslink density found in energy-storing tendons compared to positional tendons. The insights gained from this study could help management of tendon and other musculoskeletal injuries by targeting collagen molecular damage at the fibril level. STATEMENT OF SIGNIFICANCE: When tendons are stretched or torn, this can lead to collagen denaturation (damage). Depending on their biomechanical function, tendons are considered positional or energy-storing with different crosslink profiles. By stretching collagen fibrils instead of fascicles from both tendon types, we can more directly examine the effect of tensile stretch on the collagen molecule in tendons. We found that regardless of tendon type, collagen denaturation in fibrils occurs when they are stretched beyond the yield point of the stress-strain curve. This provides insight into how load affects different tendon sub-structures during tendon injuries and failure, which will help clinicians and researchers understand mechanisms of injuries and potentially target collagen molecular damage as a treatment strategy, leading to improved clinical outcomes following injury.
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Affiliation(s)
- Allen H Lin
- Department of Biomedical Engineering, University of Utah, United States; Scientific Computing and Imaging Institute, University of Utah, United States
| | - Christopher A Slater
- Department of Biomedical Engineering, Case Western Reserve University, United States
| | - Callie-Jo Martinez
- Department of Biomedical Engineering, University of Utah, United States; Scientific Computing and Imaging Institute, University of Utah, United States
| | - Steven J Eppell
- Department of Biomedical Engineering, Case Western Reserve University, United States
| | - S Michael Yu
- Department of Biomedical Engineering, University of Utah, United States; Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, United States
| | - Jeffrey A Weiss
- Department of Biomedical Engineering, University of Utah, United States; Scientific Computing and Imaging Institute, University of Utah, United States; Department of Orthopaedics, University of Utah, United States.
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11
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Kim J, Baek SY, Schlecht SH, Beaulieu ML, Bussau L, Chen J, Ashton-Miller JA, Wojtys EM, Banaszak Holl MM. Anterior cruciate ligament microfatigue damage detected by collagen autofluorescence in situ. J Exp Orthop 2022; 9:74. [PMID: 35907038 PMCID: PMC9339057 DOI: 10.1186/s40634-022-00507-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 07/12/2022] [Indexed: 11/10/2022] Open
Abstract
PURPOSE Certain types of repetitive sub-maximal knee loading cause microfatigue damage in the human anterior cruciate ligament (ACL) that can accumulate to produce macroscopic tissue failure. However, monitoring the progression of that ACL microfatigue damage as a function of loading cycles has not been reported. To explore the fatigue process, a confocal laser endomicroscope (CLEM) was employed to capture sub-micron resolution fluorescence images of the tissue in situ. The goal of this study was to quantify the in situ changes in ACL autofluorescence (AF) signal intensity and collagen microstructure as a function of the number of loading cycles. METHODS Three paired and four single cadaveric knees were subjected to a repeated 4 times bodyweight landing maneuver known to strain the ACL. The paired knees were used to compare the development of ACL microfatigue damage on the loaded knee after 100 consecutive loading cycles, relative to the contralateral unloaded control knee, through second harmonic generation (SHG) and AF imaging using confocal microscopy (CM). The four single knees were used for monitoring progressive ACL microfatigue damage development by AF imaging using CLEM. RESULTS The loaded knees from each pair exhibited a statistically significant increase in AF signal intensity and decrease in SHG signal intensity as compared to the contralateral control knees. Additionally, the anisotropy of the collagen fibers in the loaded knees increased as indicated by the reduced coherency coefficient. Two out of the four single knee ACLs failed during fatigue loading, and they exhibited an order of magnitude higher increase in autofluorescence intensity per loading cycle as compared to the intact knees. Of the three regions of the ACL - proximal, midsubstance and distal - the proximal region of ACL fibers exhibited the highest AF intensity change and anisotropy of fibers. CONCLUSIONS CLEM can capture changes in ACL AF and collagen microstructures in situ during and after microfatigue damage development. Results suggest a large increase in AF may occur in the final few cycles immediately prior to or at failure, representing a greater plastic deformation of the tissue. This reinforces the argument that existing microfatigue damage can accumulate to induce bulk mechanical failure in ACL injuries. The variation in fiber organization changes in the ACL regions with application of load is consistent with the known differences in loading distribution at the ACL femoral enthesis.
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Affiliation(s)
- Jinhee Kim
- Department of Chemical & Biological Engineering, Monash University, Melbourne, Australia.,Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - So Young Baek
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Stephen H Schlecht
- Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Mélanie L Beaulieu
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA
| | | | - Junjie Chen
- Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
| | | | - Edward M Wojtys
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA.
| | - Mark M Banaszak Holl
- Department of Chemical & Biological Engineering, Monash University, Melbourne, Australia.
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Fontenele FF, Bouklas N. Understanding the inelastic response of collagen fibrils: A viscoelastic-plastic constitutive model. Acta Biomater 2022; 163:78-90. [PMID: 35835288 DOI: 10.1016/j.actbio.2022.07.011] [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: 03/30/2022] [Revised: 07/01/2022] [Accepted: 07/05/2022] [Indexed: 11/01/2022]
Abstract
Collagen fibrils, which are the lowest level fibrillar unit of organization of collagen, are thus of primary interest towards understanding the mechanical behavior of load-bearing soft tissues. The deformation of collagen fibrils shows unique mechanical features; namely, their high energy dissipation is even superior compared to most engineering materials. Additionally, there are indications that cyclic loading can further improve the toughness of collagen fibrils. Recent experiments from Liu at al. (2018) focused on the response of type I collagen fibrils to uniaxial cyclic loading, revealing some interesting results regarding their rate-dependent and inelastic response. In this work, we aim to develop a model that allows interpreting the complex nonlinear and inelastic response of collagen fibrils under cyclic loading. We propose a constitutive model that accounts for viscoelastic deformations through a decoupled strain-energy density function (into an elastic and a viscous parts), and for plastic deformations through plastic evolution laws. The stress-stretch response results obtained using this constitutive law showed good agreement with experimental data over complex loading paths. Ultimately we use the model to gain more insights on how cyclic loading and rate effects control the interplay between viscoelastic and plastic deformation in collagen fibrils, and to extrapolate the results from experimental data, analyzing how complex cyclic load influences energy dissipation and deformation mechanisms. STATEMENT OF SIGNIFICANCE: In this work, we develop a viscoelastic-plastic constitutive model for collagen fibrils with the aim of analyzing the effects of inelasticity and energy dissipation in this material, and more specifically the competition between viscoelasticity and plasticity in the context of cyclic loading and overload. Experimental and theoretical approaches so far have not fully clarified the interplay between viscous and plastic deformations during cyclic loading of collagen fibrils. Here, we aim to interpret the complex nonlinear response of collagen fibrils and, ultimately, suggest predictive capabilities that can inform tissue-level response and injury. To validate our model, we compare our results against the stress-stretch data obtained from experiments of cyclic loaded single fibrils performed by Liu et al. (2018).
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Affiliation(s)
- Fernanda F Fontenele
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, NY 14853, USA
| | - Nikolaos Bouklas
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, NY 14853, USA.
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13
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Yang F, Das D, Chasiotis I. Strain rate induced toughening of individual collagen fibrils. APPLIED PHYSICS LETTERS 2022; 120:114101. [PMID: 35355883 PMCID: PMC8934191 DOI: 10.1063/5.0084054] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Accepted: 02/27/2022] [Indexed: 06/14/2023]
Abstract
The nonlinear mechanical behavior of individual nanoscale collagen fibrils is governed by molecular stretching and sliding that result in a viscous response, which is still not fully understood. Toward this goal, the in vitro mechanical behavior of individual reconstituted mammalian collagen fibrils was quantified in a broad range of strain-rates, spanning roughly six orders of magnitude, from 10-4 to 35 s-1. It is shown that the nonlinear mechanical response is strain rate sensitive with the tangent modulus in the linear deformation regime increasing monotonically from 214 ± 8 to 358 ± 11 MPa. More pronounced is the effect of the strain rate on the ultimate tensile strength that is found to increase monotonically by a factor of four, from 42 ± 6 to 160 ± 14 MPa. Importantly, fibril strengthening takes place without a reduction in ductility, which results in equivalently large increase in toughness with the increasing strain rate. This experimental strain rate dependent mechanical response is captured well by a structural constitutive model that incorporates the salient features of the collagen microstructure via a process of gradual recruitment of kinked tropocollagen molecules, thus giving rise to the initial "toe-heel" mechanical behavior, followed by molecular stretching and sustained intermolecular slip that is initiated at a strain rate dependent stress threshold. The model shows that the fraction of tropocollagen molecules undergoing straightening increases continuously during loading, whereas molecular sliding is initiated after a small fibril strain (1%-2%) and progressively increases with applied strain.
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14
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Hasan F, Al Mahmud KAH, Khan MI, Kang W, Adnan A. Effect of random fiber networks on bubble growth in gelatin hydrogels. SOFT MATTER 2021; 17:9293-9314. [PMID: 34647568 DOI: 10.1039/d1sm00587a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In hydrodynamics, the event of dynamic bubble growth in a pure liquid under tensile pressure is known as cavitation. The same event can also be observed in soft materials (e.g., elastomers and hydrogels). However, for soft materials, bubble/cavity growth is either defined as cavitation if the bubble growth is elastic and reversible or as fracture if the cavity growth is by material failure and irreversible. In any way, bubble growth can cause damage to soft materials (e.g., tissue) by inducing high strain and strain-rate deformation. Additionally, a high-strength pressure wave is generated upon the collapse of the bubble. Therefore, it is crucial to identify the critical condition of spontaneous bubble growth in soft materials. Experimental and theoretical observations have agreed that the onset of bubble growth in soft materials requires higher tensile pressure than pure water. The extra tensile pressure is required since the cavitating bubble needs to overcome the elastic and surface energy in soft materials. In this manuscript, we developed two models to study and quantify the extra tensile pressure for different gelatin concentrations. Both the models are then compared with the existing cavitation onset criteria of rubber-like materials. Validation is done with the experimental results of threshold tensile pressure for different gelatin concentrations. Both models can moderately predict the extra tensile pressure within the intermediate range of gelatin concentrations (3-7% [w/v]). For low concentration (∼1%), the network's non-affinity plays a significant role and must be incorporated. On the other hand, for higher concentrations (∼10%), the entropic deformation dominates, and the strain energy formulation is not adequate.
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Affiliation(s)
- Fuad Hasan
- Department of Mechanical and Aerospace Engineering, The University of Texas at Arlington, USA.
- Woolf Hall, Room 315C, Arlington, TX 76019, USA
| | - K A H Al Mahmud
- Department of Mechanical and Aerospace Engineering, The University of Texas at Arlington, USA.
- Woolf Hall, Room 315C, Arlington, TX 76019, USA
| | - Md Ishak Khan
- Department of Mechanical and Aerospace Engineering, The University of Texas at Arlington, USA.
- Woolf Hall, Room 315C, Arlington, TX 76019, USA
| | - Wonmo Kang
- School for Engineering of Matter, Transport and Energy, Arizona State University, USA
| | - Ashfaq Adnan
- Department of Mechanical and Aerospace Engineering, The University of Texas at Arlington, USA.
- Woolf Hall, Room 315C, Arlington, TX 76019, USA
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15
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The Effect of Enzymatic Crosslink Degradation on the Mechanics of the Anterior Cruciate Ligament: A Hybrid Multi-Domain Model. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11188580] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The anterior cruciate ligament’s (ACL) mechanics is an important factor governing the ligament’s integrity and, hence, the knee joint’s response. Despite many investigations in this area, the cause and effect of injuries remain unclear or unknown. This may be due to the complexity of the direct link between macro- and micro-scale damage mechanisms. In the first part of this investigation, a three-dimensional coarse-grained model of collagen fibril (type I) was developed using a bottom-up approach to investigate deformation mechanisms under tensile testing. The output of this molecular level was used later to calibrate the parameters of a hierarchical multi-scale fibril-reinforced hyper-elastoplastic model of the ACL. Our model enabled us to determine the mechanical behavior of the ACL as a function of the basic response of the collagen molecules. Modeled elastic response and damage distribution were in good agreement with the reported measurements and computational investigations. Our results suggest that degradation of crosslink content dictates the loss of the stiffness of the fibrils and, hence, damage to the ACL. Therefore, the proposed computational frame is a promising tool that will allow new insights into the biomechanics of the ACL.
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Abstract
Studying changes in collagen deformation behavior at the nanoscale due to variations in mineralization and hydration is important for characterizing and developing collagen-based bio-composites. Recent studies also find that carbon nanotubes (CNTs) show promise as a reinforcing material for collagenous bio-composites. Currently, the effects of variation in mineral, water, and CNT content on collagen gap and overlap region mechanics during compression is unexplored. We use molecular dynamics simulations to investigate how variations in mineral, water, and CNT contents of collagen bio-composites in compression change their deformation behavior and thermal properties. Results indicate that variations in mineral and water content affect the collagen structure due to expansion or contraction of the gap and overlap regions. The deformation mechanisms of the gap and overlap regions also change. The presence of CNTs in non-mineralized collagen reduces the deformation of the gap region and increases the bio-composite elastic modulus to ranges comparable to mineralized collagen. The collagen/CNT bio-composites are also determined to have a higher specific heat than the studied mineralized collagen bio-composites, making them more likely to be resistant to thermal damage that could occur during implantation or functional use of a collagen collagen/CNT bio-composite biomaterial.
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Affiliation(s)
- Marco Fielder
- Multiscale Materials Modeling Lab, Department of Mechanical Engineering, University of Arkansas , Fayetteville, AR, USA
| | - Arun K Nair
- Multiscale Materials Modeling Lab, Department of Mechanical Engineering, University of Arkansas , Fayetteville, AR, USA.,Institute for Nanoscience and Engineering, University of Arkansas , Fayetteville, AR, USA
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17
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Wang R, Yu X, Gkousioudi A, Zhang Y. Effect of Glycation on Interlamellar Bonding of Arterial Elastin. EXPERIMENTAL MECHANICS 2021; 61:81-94. [PMID: 33583947 PMCID: PMC7880226 DOI: 10.1007/s11340-020-00644-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 07/21/2020] [Indexed: 06/12/2023]
Abstract
BACKGROUND Interlamellar bonding in the arterial wall is often compromised by cardiovascular diseases. However, several recent nationwide and hospital-based studies have uniformly reported reduced risk of thoracic aortic dissection in patients with diabetes. As one of the primary structural constituents in the arterial wall, elastin plays an important role in providing its interlamellar structural integrity. OBJECTIVE The purpose of this study is to examine the effects of glycation on the interlamellar bonding properties of arterial elastin. METHODS Purified elastin network was isolated from porcine descending thoracic aorta and incubated in 2 M glucose solution for 7, 14 or 21 days at 37 °C. Peeling and direct tension tests were performed to provide complimentary information on understanding the interlamellar layer separation properties of elastin network with glycation effect. Peeling tests were simulated using a cohesive zone model (CZM). Multiphoton imaging was used to visualize the interlamellar elastin fibers in samples subjected to peeling and direct tension. RESULTS Peeling and direct tension tests show that interlamellar energy release rate and strength both increases with the duration of glucose treatment. The traction at damage initiation estimated for the CZM agrees well with the interlamellar strength measurements from direct tension tests. Glycation was also found to increase the interlamellar failure strain of arterial elastin. Multiphoton imaging confirmed the contribution of radially running elastin fibers to resisting dissection. CONCLUSIONS Nonenzymatic glycation reduces the propensity of arterial elastin to dissection. This study also suggests that the CZM effectively describes the interlamellar bonding properties of arterial elastin.
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Affiliation(s)
- R Wang
- Department of Mechanical Engineering, Boston University, Boston, MA 02215
| | - X Yu
- Department of Mechanical Engineering, Boston University, Boston, MA 02215
| | - A Gkousioudi
- Department of Mechanical Engineering, Boston University, Boston, MA 02215
| | - Y Zhang
- Department of Mechanical Engineering, Boston University, Boston, MA 02215
- Department of Biomedical Engineering, Boston University, Boston, MA 02215
- Divison of Materials Science & Engineering, Boston University, Boston, MA 02215
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18
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Adouni M, Mbarki R, Al Khatib F, Eilaghi A. Multiscale modeling of knee ligament biomechanics. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2021; 37:e3413. [PMID: 33174350 DOI: 10.1002/cnm.3413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 10/02/2020] [Accepted: 11/01/2020] [Indexed: 06/11/2023]
Abstract
Knee connective tissues are mainly responsible for joint stability and play a crucial role in restraining excessive motion during regular activities. The damage mechanism of these tissues is directly linked to the microscale collagen level. However, this mechanical connection is still unclear. During this investigation, a multiscale fibril-reinforced hyper-elastoplastic model was developed and statistically calibrated. The model is accounting for the structural architecture of the soft tissue, starting from the tropocollagen molecule that forms fibrils to the whole soft tissue. Model predictions are in agreement with the results of experimental and numerical studies. Further, damage initiation and propagation in the collagen fiber were computed at knee ligaments and located mainly in the superficial layers. Results indicated higher crosslink density required higher tensile stress to elicit fibril damage. This approach is aligned with a realistic simulation of a damaging process and repair attempt. To the best of our knowledge, this is the first model published in which the connective tissue stiffness is simultaneously predicted by encompassing the mesoscopic scales between the molecular and macroscopic levels.
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Affiliation(s)
- Malek Adouni
- Physical Medicine and Rehabilitation Department, Northwestern University, Chicago, Illinois, USA
- Mechanical Engineering Department, Australian College of Kuwait, Kuwait city, Kuwait
| | - Raouf Mbarki
- Mechanical Engineering Department, Australian College of Kuwait, Kuwait city, Kuwait
| | - Fadi Al Khatib
- Mechanical Engineering Department, Australian College of Kuwait, Kuwait city, Kuwait
| | - Armin Eilaghi
- Mechanical Engineering Department, Australian College of Kuwait, Kuwait city, Kuwait
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19
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Atthapreyangkul A, Hoffman M, Pearce G. Effect of geometrical structure variations on the viscoelastic and anisotropic behaviour of cortical bone using multi-scale finite element modelling. J Mech Behav Biomed Mater 2020; 113:104153. [PMID: 33125948 DOI: 10.1016/j.jmbbm.2020.104153] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 10/10/2020] [Accepted: 10/21/2020] [Indexed: 11/25/2022]
Abstract
Multi-scale finite element analysis is performed to ascertain the effect of geometrical changes at multiple structural scales on the mechanical properties of cortical bone. Finite element models are developed, with reference to experimental data from existing literature, to account for bone's viscoelastic behaviour and anisotropic structure from the most fundamental level of bone consisting of mineralised collagen fibrils, up to the macroscopic level consisting of osteons and the Haversian canals. A statistical approach is incorporated to perform sensitivity analyses on the effects of different geometrical parameters on the effective material properties of cortical bone at each length scale. Numerical results indicate that there is an exponential correlation between the mineral volume fraction and the effective stiffness constants at each length scale. This contributes to the exponential behaviour of the instantaneous moduli describing cortical bone's two-phase stress relaxation process: a fast and slow response relaxation behaviour. Results indicate that the fast response relaxation time is independent of bone's structural anisotropy, whilst being dependent on variations in the global mineral volume fraction between length scales. However, the slow response relaxation time is independent of the changes in mineral volume fraction. It is also observed that the slow response relaxation time varies with bone's anisotropic structure, and therefore, contributes to the anisotropic properties of bone.
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Affiliation(s)
| | - Mark Hoffman
- School of Materials Science and Engineering, UNSW, Sydney, NSW, 2052, Australia; School of Mechanical and Manufacturing Engineering, UNSW, Sydney, NSW, 2052, Australia; School of Engineering, The University of Newcastle, NSW, 2308, Australia.
| | - Garth Pearce
- School of Mechanical and Manufacturing Engineering, UNSW, Sydney, NSW, 2052, Australia
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20
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Wang R, Yu X, Zhang Y. Mechanical and structural contributions of elastin and collagen fibers to interlamellar bonding in the arterial wall. Biomech Model Mechanobiol 2020; 20:93-106. [PMID: 32705413 DOI: 10.1007/s10237-020-01370-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 07/15/2020] [Indexed: 12/25/2022]
Abstract
The artery relies on interlamellar structural components, mainly elastin and collagen fibers, for maintaining its integrity and resisting dissection propagation. In this study, the contribution of arterial elastin and collagen fibers to interlamellar bonding was studied through mechanical testing, multiphoton imaging and finite element modeling. Steady-state peeling experiments were performed on porcine aortic media and the purified elastin network in the circumferential (Circ) and longitudinal (Long) directions. The peeling force and energy release rate associated with mode-I failure are much higher for aortic media than for the elastin network. Also, longitudinal peeling exhibits a higher energy release rate and strength than circumferential peeling for both the aortic media and elastin. Multiphoton imaging shows the recruitment of both elastin and collagen fibers within the interlamellar space and points to in-plane anisotropy of fiber distributions as a potential mechanism for the direction-dependent phenomena of peeling tests. Three-dimensional finite element models based on cohesive zone model (CZM) of fracture were created to simulate the peeling tests with the interlamellar energy release rate and separation distance at damage initiation obtained directly from peeling test. Our experimental results show that the separation distance at damage initiation is 80 μm for aortic media and 40 μm for elastin. The damage initiation stress was estimated from the model for aortic media (Circ: 60 kPa; Long: 95 kPa) and elastin (Circ: 9 kPa; Long: 14 kPa). The interlamellar separation distance at complete failure was estimated to be 3 - 4 mm for both media and elastin. Furthermore, elastin and collagen fibers both play an important role in bonding of the arterial wall, while collagen has a higher contribution than elastin to interlamellar stiffness, strength and toughness. These results on microstructural interlamellar failure shed light on the pathological development and progression of aortic dissection.
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Affiliation(s)
- Ruizhi Wang
- Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA
| | - Xunjie Yu
- Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA
| | - Yanhang Zhang
- Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA. .,Department of Biomedical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA. .,Divison of Materials Science & Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA.
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21
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An efficient two-scale 3D FE model of the bone fibril array: comparison of anisotropic elastic properties with analytical methods and micro-sample testing. Biomech Model Mechanobiol 2020; 19:2127-2147. [DOI: 10.1007/s10237-020-01328-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Accepted: 04/11/2020] [Indexed: 12/14/2022]
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22
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Tohidnezhad M, Zander J, Slowik A, Kubo Y, Dursun G, Willenberg W, Zendedel A, Kweider N, Stoffel M, Pufe T. Impact of Uniaxial Stretching on Both Gliding and Traction Areas of Tendon Explants in a Novel Bioreactor. Int J Mol Sci 2020; 21:ijms21082925. [PMID: 32331279 PMCID: PMC7215532 DOI: 10.3390/ijms21082925] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 04/03/2020] [Accepted: 04/16/2020] [Indexed: 12/14/2022] Open
Abstract
The effects of mechanical stress on cells and their extracellular matrix, especially in gliding sections of tendon, are still poorly understood. This study sought to compare the effects of uniaxial stretching on both gliding and traction areas in the same tendon. Flexor digitorum longus muscle tendons explanted from rats were subjected to stretching in a bioreactor for 6, 24, or 48 h, respectively, at 1 Hz and an amplitude of 2.5%. After stimulation, marker expression was quantified by histological and immunohistochemical staining in both gliding and traction areas. We observed a heightened intensity of scleraxis after 6 and 24 h of stimulation in both tendon types, though it had declined again 48 h after stimulation. We observed induced matrix metalloproteinase-1 and -13 protein expression in both tendon types. The bioreactor produced an increase in the mechanical structural strength of the tendon during the first half of the loading time and a decrease during the latter half. Uniaxial stretching of flexor tendon in our set-up can serve as an overloading model. A combination of mechanical and histological data allows us to improve the conditions for cultivating tendon tissues.
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Affiliation(s)
- Mersedeh Tohidnezhad
- Anatomy and Cell Biology, Uniklinik RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany; (J.Z.); (Y.K.); (N.K.); (T.P.)
- Correspondence: ; Tel.: +49-241-80-89550; Fax: +49-241-80-82431
| | - Johanna Zander
- Anatomy and Cell Biology, Uniklinik RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany; (J.Z.); (Y.K.); (N.K.); (T.P.)
| | - Alexander Slowik
- Institute of Neuroanatomy, Uniklinik RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany; (A.S.); (A.Z.)
| | - Yusuke Kubo
- Anatomy and Cell Biology, Uniklinik RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany; (J.Z.); (Y.K.); (N.K.); (T.P.)
| | - Gözde Dursun
- Institute of General Mechanics, RWTH Aachen University, Templergraben 64, 52056 Aachen, Germany; (G.D.); (W.W.); (M.S.)
| | - Wolfgang Willenberg
- Institute of General Mechanics, RWTH Aachen University, Templergraben 64, 52056 Aachen, Germany; (G.D.); (W.W.); (M.S.)
| | - Adib Zendedel
- Institute of Neuroanatomy, Uniklinik RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany; (A.S.); (A.Z.)
| | - Nisreen Kweider
- Anatomy and Cell Biology, Uniklinik RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany; (J.Z.); (Y.K.); (N.K.); (T.P.)
| | - Marcus Stoffel
- Institute of General Mechanics, RWTH Aachen University, Templergraben 64, 52056 Aachen, Germany; (G.D.); (W.W.); (M.S.)
| | - Thomas Pufe
- Anatomy and Cell Biology, Uniklinik RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany; (J.Z.); (Y.K.); (N.K.); (T.P.)
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Ferruzzi J, Zhang Y, Roblyer D, Zaman MH. Multi-scale Mechanics of Collagen Networks: Biomechanical Basis of Matrix Remodeling in Cancer. MULTI-SCALE EXTRACELLULAR MATRIX MECHANICS AND MECHANOBIOLOGY 2020. [DOI: 10.1007/978-3-030-20182-1_11] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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A multiscale synthesis: characterizing acute cartilage failure under an aggregate tibiofemoral joint loading. Biomech Model Mechanobiol 2019; 18:1563-1575. [DOI: 10.1007/s10237-019-01159-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 04/26/2019] [Indexed: 02/02/2023]
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25
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Meyer M. Processing of collagen based biomaterials and the resulting materials properties. Biomed Eng Online 2019; 18:24. [PMID: 30885217 PMCID: PMC6423854 DOI: 10.1186/s12938-019-0647-0] [Citation(s) in RCA: 235] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 03/12/2019] [Indexed: 02/07/2023] Open
Abstract
Collagen, the most abundant extracellular matrix protein in animal kingdom belongs to a family of fibrous proteins, which transfer load in tissues and which provide a highly biocompatible environment for cells. This high biocompatibility makes collagen a perfect biomaterial for implantable medical products and scaffolds for in vitro testing systems. To manufacture collagen based solutions, porous sponges, membranes and threads for surgical and dental purposes or cell culture matrices, collagen rich tissues as skin and tendon of mammals are intensively processed by physical and chemical means. Other tissues such as pericardium and intestine are more gently decellularized while maintaining their complex collagenous architectures. Tissue processing technologies are organized as a series of steps, which are combined in different ways to manufacture structurally versatile materials with varying properties in strength, stability against temperature and enzymatic degradation and cellular response. Complex structures are achieved by combined technologies. Different drying techniques are performed with sterilisation steps and the preparation of porous structures simultaneously. Chemical crosslinking is combined with casting steps as spinning, moulding or additive manufacturing techniques. Important progress is expected by using collagen based bio-inks, which can be formed into 3D structures and combined with live cells. This review will give an overview of the technological principles of processing collagen rich tissues down to collagen hydrolysates and the methods to rebuild differently shaped products. The effects of the processing steps on the final materials properties are discussed especially with regard to the thermal and the physical properties and the susceptibility to enzymatic degradation. These properties are key features for biological and clinical application, handling and metabolization.
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Affiliation(s)
- Michael Meyer
- Research Institute for Leather and Plastic Sheeting, Meissner Ring 1-5, 09599, Freiberg, Germany.
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26
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Awasthi A, Sharma R, Ghosh R. Monte Carlo type Simulations of Mineralized Collagen Fibril based on Two Scale Asymptotic Homogenization. J Biomech Eng 2019; 141:2720657. [PMID: 30615067 DOI: 10.1115/1.4042439] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Indexed: 11/08/2022]
Abstract
A multi-scale model for mineralized collagen fibril is proposed by taking into account the uncertainties associated with the geometrical properties of mineral phase and its distribution in the organic matrix. The asymptotic homogenization approach along with periodic boundary conditions has been used to derive the effective elastic moduli at two hierarchical length scales, namely: microfibril and mineralized collagen fibril. The uncertainties associated with the mineral plates have been directly included in the finite element mesh by randomly varying their sizes. A total 100 realizations for mineralized collagen fibril model with random distribution have been generated using an in-house MATLAB® code and Monte-Carlo type simulations have been performed under tension load to obtain the statistical equivalent modulus. The deformation response has been studied in both small (= 10%) and large (= 10%) strain regimes. The stress transformation mechanism has also been explored in microfibril which showed stress relaxation in the organic phase upon different stages of mineralization. The elastic moduli for microfibril under small and large strain have been obtained as 1.88 and 6.102 GPa, respectively, and have been used as input for upper scale homogenization procedure. Finally, the characteristic longitudinal moduli of the mineralized collagen fibril in the small and large strain regimes are obtained as 4.08 ± 0.062 and 12.93 ± 0.148 GPa, respectively. All the results are in good agreement to those obtained from previous experiments and molecular dynamics simulations in the literature with a significant reduction in the computational cost.
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Affiliation(s)
- Abhilash Awasthi
- MS Scholar, School of Engineering, Indian Institute of Technology Mandi, Kamand - 175005, Mandi, Himachal Pradesh, India
| | - Rajneesh Sharma
- Assistant Professor, School of Engineering, Indian Institute of Technology Mandi, Kamand - 175005, Mandi, Himachal Pradesh, India
| | - Rajesh Ghosh
- Assistant Professor, School of Engineering, Indian Institute of Technology Mandi, Kamand - 175005, Mandi, Himachal Pradesh, India
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27
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Faisal TR, Adouni M, Dhaher YY. The effect of fibrillar degradation on the mechanics of articular cartilage: a computational model. Biomech Model Mechanobiol 2019; 18:733-751. [DOI: 10.1007/s10237-018-01112-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 12/20/2018] [Indexed: 12/21/2022]
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28
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Abstract
The hierarchical structure of tendon allows for attenuation of mechanical strain down decreasing length scales. While reorganization of collagen fibers accounts for microscale strain attenuation, cross-linking between collagen molecules contributes to deformation mechanisms at the fibrillar and molecular scales. Divalent and trivalent enzymatic cross-links form during the development of collagen fibrils through the enzymatic activity of lysyl oxidase (LOX). By establishing connections between telopeptidyl and triple-helical domains of adjacent molecules within collagen fibrils, these cross-links stiffen the fibrils by resisting intermolecular sliding. Ultimately, greater enzymatic cross-linking leads to less compliant and stronger tendon as a result of stiffer fibrils. In contrast, nonenzymatic cross-links such as glucosepane and pentosidine are not produced during development but slowly accumulate through glycation of collagen. Therefore, these cross-links are only expected to be present in significant quantities in advanced age, where there has been sufficient time for glycation to occur, and in diabetes, where the presence of more free sugar in the extracellular matrix increases the rate of glycation. Unlike enzymatic cross-links, current evidence suggests that nonenzymatic cross-links are at least partially isolated to the surface of collagen fibers. As a result, glycation has been proposed to primarily impact tendon mechanics by altering molecular interactions at the fiber interface, thereby diminishing sliding between fibers. Thus, increased nonenzymatic cross-linking decreases microscale strain attenuation and the viscous response of tendon. In conclusion, enzymatic and nonenzymatic collagen cross-links have demonstrable and distinct effects on the mechanical properties of tendon across different length scales.
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Affiliation(s)
- Jeremy D Eekhoff
- a Department of Biomedical Engineering , Washington University in St. Louis , St. Louis , USA
| | - Fei Fang
- b Department of Orthopedic Surgery , Columbia University , New York , USA
| | - Spencer P Lake
- a Department of Biomedical Engineering , Washington University in St. Louis , St. Louis , USA.,c Department of Mechanical Engineering and Materials Science , Washington University in St. Louis , St. Louis , USA.,d Department of Orthopaedic Surgery , Washington University in St. Louis , St. Louis , USA
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Fielder M, Nair AK. Effects of hydration and mineralization on the deformation mechanisms of collagen fibrils in bone at the nanoscale. Biomech Model Mechanobiol 2018; 18:57-68. [PMID: 30088113 DOI: 10.1007/s10237-018-1067-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 07/30/2018] [Indexed: 12/25/2022]
Abstract
Bone is a biomaterial with a structural load-bearing function. Investigating the biomechanics of bone at the nanoscale is important in application to tissue engineering, the development of bioinspired materials, and for characterizing factors such as age, trauma, or disease. At the nanoscale, bone is composed of fibrils that are primarily a composite of collagen, apatite crystals (mineral), and water. Though several studies have been done characterizing the mechanics of fibrils, the effects of variation and distribution of water and mineral content in fibril gap and overlap regions are unexplored. We investigate how the deformation mechanisms of collagen fibrils change as a function of mineral and water content. We use molecular dynamics to study the mechanics of collagen fibrils of 0 wt%, 20 wt%, and 40 wt% mineralization and 0 wt%, 2 wt%, and 4 wt% hydration under applied tensile stresses. We observe that the stress-strain behavior becomes more nonlinear with an increase in hydration, and an increase in mineral content for hydrated fibrils under tensile stress reduces the nonlinear stress versus strain behavior caused by hydration. The Young's modulus of both non-mineralized and mineralized fibrils decreases as the water content increases. As the water content increases, the gap/overlap ratio increases by approximately 40% for the non-mineralized cases and 16% for the highly mineralized cases. Our results indicate that variations in mineral and water content change the distribution of water in collagen fibrils and that the water distribution changes the deformation of gap and overlap regions under tensile loading.
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Affiliation(s)
- Marco Fielder
- Multiscale Materials Modeling Lab, Department of Mechanical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Arun K Nair
- Multiscale Materials Modeling Lab, Department of Mechanical Engineering, University of Arkansas, Fayetteville, AR, USA. .,Institute for Nanoscience and Engineering, University of Arkansas, 731 W. Dickson Street, Fayetteville, AR, USA.
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Tehrani M, Ghalamzan Z, Sarvestani A. Polydispersity controls the strength of semi-flexible polymer networks. Phys Biol 2018; 15:066002. [PMID: 29771241 DOI: 10.1088/1478-3975/aac5a8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The classical theory of polymer elasticity is built upon the assumption of network monodispersity-the premise that polymer networks are comprised of sub-chains of equal length. The crosslinking of biopolymers, however, is a random process and the resultant networks are likely to be polydisperse. The effect of structural polydispersity on the mechanical behavior of biopolymer networks is not well understood. The purpose of this contribution is to show how network polydispersity controls mechanical behavior and the ultimate properties of crosslinked semi-flexible filaments at finite deformations. The proposed micromechanical continuum model is based on the force-elongation relation of individual chains of different lengths. It is shown that the mechanical strength of the network is controlled by the finite-extensibility of filaments and the degradation of shorter filaments at relatively small stretches. The progressive failure of filaments continues and eventually determines the ultimate strength of the network. The predicted stress-stretch behaviors are in reasonable agreement with the experimental data for connective tissues.
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Affiliation(s)
- Mohammad Tehrani
- Department of Mechanical Engineering, Ohio University, Athens, OH 45701, United States of America
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31
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Pond D, McBride A, Davids L, Reddy B, Limbert G. Microstructurally-based constitutive modelling of the skin – Linking intrinsic ageing to microstructural parameters. J Theor Biol 2018; 444:108-123. [DOI: 10.1016/j.jtbi.2018.01.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 12/21/2017] [Accepted: 01/15/2018] [Indexed: 10/18/2022]
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Deformation regimes of collagen fibrils in cortical bone revealed by in situ morphology and elastic modulus observations under mechanical loading. J Mech Behav Biomed Mater 2018; 79:115-121. [DOI: 10.1016/j.jmbbm.2017.12.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 11/21/2017] [Accepted: 12/14/2017] [Indexed: 01/14/2023]
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Takahashi N, Hirose T, Minaguchi JA, Ueda H, Tangkawattana P, Takehana K. Fibrillar architecture at three different sites of the bovine superficial digital flexor tendon. J Vet Med Sci 2018; 80:405-412. [PMID: 29332865 PMCID: PMC5880818 DOI: 10.1292/jvms.17-0562] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Superficial digital flexor tendon (SDFT) of the bovine hindlimb originates from the caudolateral aspect of the distal femur and finally inserts onto the plantar aspect of the middle phalanges. In the present study,
morphology and morphometry of the bovine SDFT at the muscle-tendon junction (MTJ), middle metatarsus (mM) and tendon-bone interface (TBI) were investigated. Cross-sectional morphology at the three regions of SDFT were
oval, semioval and ring-formed, respectively. Significant difference in cross-sectional area was found only between MTJ-mM and mM-TBI (P<0.05). Functional compression and friction from the adjacent
structures could be the most potential interactions affecting such appearances. Morphometric data of tenocyte number, water content, and glycosaminoglycan (GAG) length and angle were found increasing in the proximodistal
direction, except the fibril diameter and collagen fibril index (CFI). Statistical analyzes could reveal significant differences in average number of tenocytes (P<0.0001), CFI (between MTJ-mM and
MTJ-TBI, P<0.05), water content (between MTJ-TBI, P<0.05), length of GAG chains (between MTJ-TBI, P<0.05), and angle of GAG chains
(P<0.0001), respectively. The fibrillar characteristics at the three different areas, including fibril diameter distribution and interfibrillar distance, existed in conforming to the tensional axes in
situ. In addition, length and angle of GAG chains were relevant to moving directions of the collagen fibrils.
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Affiliation(s)
- Naoki Takahashi
- Laboratory of Veterinary Microanatomy, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
| | - Takuya Hirose
- Laboratory of Veterinary Microanatomy, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
| | - Jun A Minaguchi
- Laboratory of Veterinary Microanatomy, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
| | - Hiromi Ueda
- Laboratory of Veterinary Anatomy, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
| | - Prasarn Tangkawattana
- Laboratory of Veterinary Microanatomy, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan.,Department of Veterinary Anatomy, Faculty of Veterinary Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand
| | - Kazushige Takehana
- Laboratory of Veterinary Microanatomy, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
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Planz V, Seif S, Atchison JS, Vukosavljevic B, Sparenberg L, Kroner E, Windbergs M. Three-dimensional hierarchical cultivation of human skin cells on bio-adaptive hybrid fibers. Integr Biol (Camb) 2017; 8:775-84. [PMID: 27241237 DOI: 10.1039/c6ib00080k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The human skin comprises a complex multi-scale layered structure with hierarchical organization of different cells within the extracellular matrix (ECM). This supportive fiber-reinforced structure provides a dynamically changing microenvironment with specific topographical, mechanical and biochemical cell recognition sites to facilitate cell attachment and proliferation. Current advances in developing artificial matrices for cultivation of human cells concentrate on surface functionalizing of biocompatible materials with different biomolecules like growth factors to enhance cell attachment. However, an often neglected aspect for efficient modulation of cell-matrix interactions is posed by the mechanical characteristics of such artificial matrices. To address this issue, we fabricated biocompatible hybrid fibers simulating the complex biomechanical characteristics of native ECM in human skin. Subsequently, we analyzed interactions of such fibers with human skin cells focusing on the identification of key fiber characteristics for optimized cell-matrix interactions. We successfully identified the mediating effect of bio-adaptive elasto-plastic stiffness paired with hydrophilic surface properties as key factors for cell attachment and proliferation, thus elucidating the synergistic role of these parameters to induce cellular responses. Co-cultivation of fibroblasts and keratinocytes on such fiber mats representing the specific cells in dermis and epidermis resulted in a hierarchical organization of dermal and epidermal tissue layers. In addition, terminal differentiation of keratinocytes at the air interface was observed. These findings provide valuable new insights into cell behaviour in three-dimensional structures and cell-material interactions which can be used for rational development of bio-inspired functional materials for advanced biomedical applications.
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Affiliation(s)
- Viktoria Planz
- Department of Biopharmaceutics and Pharmaceutical Technology, Saarland University, Campus Building A 4.1, 66123 Saarbrücken, Germany.
| | - Salem Seif
- Department of Biopharmaceutics and Pharmaceutical Technology, Saarland University, Campus Building A 4.1, 66123 Saarbrücken, Germany. and PharmBioTec GmbH, Science Park 1, 66123 Saarbrücken, Germany
| | - Jennifer S Atchison
- INM - Leibniz Institute for New Materials, Campus Building D 2.2, 66123 Saarbrücken, Germany
| | - Branko Vukosavljevic
- Helmholtz Centre for Infection Research (HZI) and Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Department of Drug Delivery (DDEL), Campus Building E 8.1, 66123 Saarbrücken, Germany
| | - Lisa Sparenberg
- Department of Biopharmaceutics and Pharmaceutical Technology, Saarland University, Campus Building A 4.1, 66123 Saarbrücken, Germany.
| | - Elmar Kroner
- INM - Leibniz Institute for New Materials, Campus Building D 2.2, 66123 Saarbrücken, Germany
| | - Maike Windbergs
- Department of Biopharmaceutics and Pharmaceutical Technology, Saarland University, Campus Building A 4.1, 66123 Saarbrücken, Germany. and PharmBioTec GmbH, Science Park 1, 66123 Saarbrücken, Germany and Helmholtz Centre for Infection Research (HZI) and Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Department of Drug Delivery (DDEL), Campus Building E 8.1, 66123 Saarbrücken, Germany
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Henak CR, Bartell LR, Cohen I, Bonassar LJ. Multiscale Strain as a Predictor of Impact-Induced Fissuring in Articular Cartilage. J Biomech Eng 2017; 139:2571657. [PMID: 27760253 DOI: 10.1115/1.4034994] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Indexed: 11/08/2022]
Abstract
Mechanical damage is central to both initiation and progression of osteoarthritis (OA). However, specific causal links between mechanics and cartilage damage are incompletely understood, which results in an inability to predict failure. The lack of understanding is primarily due to the difficulty in simultaneously resolving the high rates and small length scales relevant to the problem and in correlating such measurements to the resulting fissures. This study leveraged microscopy and high-speed imaging to resolve mechanics on the previously unexamined time and length scales of interest in cartilage damage, and used those mechanics to develop predictive models. The specific objectives of this study were to: first, quantify bulk and local mechanics during impact-induced fissuring; second, develop predictive models of fissuring based on bulk mechanics and local strain; and third, evaluate the accuracy of these models in predicting fissures. To achieve these three objectives, bovine tibial cartilage was impacted using a custom spring-loaded device mounted on an inverted microscope. The occurrence of fissures was modulated by varying impact energy. For the first objective, during impact, deformation was captured at 10,000 frames per second and bulk and local mechanics were analyzed. For the second objective, data from samples impacted with a 1.2 mm diameter rod were fit to logistic regression functions, creating models of fissure probability based on bulk and local mechanics. Finally, for the third objective, data from samples impacted with a 0.8 mm diameter rod were used to test the accuracy of model predictions. This study provides a direct comparison between bulk and local mechanical thresholds for the prediction of fissures in cartilage samples, and demonstrates that local mechanics provide more accurate predictions of local failure than bulk mechanics provide. Bulk mechanics were accurate predictors of fissure for the entire sample cohort, but poor predictors of fissure for individual samples. Local strain fields were highly heterogeneous and significant differences were determined between fissured and intact samples, indicating the presence of damage thresholds. In particular, first principal strain rate and maximum shear strain were the best predictors of local failure, as determined by concordance statistics. These data provide an important step in establishing causal links between local mechanics and cartilage damage; ultimately, data such as these can be used to link macro- and micro-scale mechanics and thereby predict mechanically mediated disease on a subject-specific basis.
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Affiliation(s)
- Corinne R Henak
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY 14853
| | - Lena R Bartell
- Department of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853
| | - Itai Cohen
- Department of Physics, Cornell University, Ithaca, NY 14853
| | - Lawrence J Bonassar
- Meinig School of Biomedical Engineering, 149 Weill Hall, Cornell University, Ithaca, NY 14853; Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14853 e-mail:
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One-hit Models of Ventilator-induced Lung Injury: Benign Inflammation versus Inflammation as a By-product. Anesthesiology 2017; 126:909-922. [PMID: 28277372 DOI: 10.1097/aln.0000000000001605] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND One important explanation for the detrimental effects of conventional mechanical ventilation is the biotrauma hypothesis that ventilation may trigger proinflammatory responses that subsequently cause lung injury. This hypothesis has frequently been studied in so-called one-hit models (overventilation of healthy lungs) that so far have failed to establish an unequivocal link between inflammation and hypoxemic lung failure. This study was designed to develop a one-hit biotrauma model. METHODS Mice (six per group) were ventilated for up to 7 h (positive end-expiratory pressure 2 cm H2O) and received 300 μl/h fluid support. Series_1: initial plateau pressures of 10, 24, 27, or 30 cm H2O. Series_2: ventilation with pressure release at 34 cm H2O and initial plateau pressure of 10, 24, 27, or 30 cm H2O. To study the significance of inflammation, the latter groups were also pretreated with the steroid dexamethasone. RESULTS Within 7 h, 20 of 24 mice ventilated with plateau pressure of 27 cm H2O or more died of a catastrophic lung failure characterized by strongly increased proinflammatory markers and a precipitous decrease in pulmonary compliance, blood pressure, and oxygenation. Pretreatment with dexamethasone reduced inflammation, but prolonged median survival time by 30 min. CONCLUSIONS Our findings demonstrate a sharp distinction between ventilation with 24 cm H2O that was well tolerated and ventilation with 27 cm H2O that was lethal for most animals due to catastrophic lung failure. In the former case, inflammation was benign and in the latter, a by-product that only accelerated lung failure. The authors suggest that biotrauma-when defined as a ventilation-induced and inflammation-dependent hypoxemia-is difficult to study in murine one-hit models of ventilation, at least not within 7 h. (Anesthesiology 2017; 126:909-22).
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37
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Goh KL, Holmes DF. Collagenous Extracellular Matrix Biomaterials for Tissue Engineering: Lessons from the Common Sea Urchin Tissue. Int J Mol Sci 2017; 18:ijms18050901. [PMID: 28441344 PMCID: PMC5454814 DOI: 10.3390/ijms18050901] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 04/05/2017] [Accepted: 04/11/2017] [Indexed: 12/21/2022] Open
Abstract
Scaffolds for tissue engineering application may be made from a collagenous extracellular matrix (ECM) of connective tissues because the ECM can mimic the functions of the target tissue. The primary sources of collagenous ECM material are calf skin and bone. However, these sources are associated with the risk of having bovine spongiform encephalopathy or transmissible spongiform encephalopathy. Alternative sources for collagenous ECM materials may be derived from livestock, e.g., pigs, and from marine animals, e.g., sea urchins. Collagenous ECM of the sea urchin possesses structural features and mechanical properties that are similar to those of mammalian ones. However, even more intriguing is that some tissues such as the ligamentous catch apparatus can exhibit mutability, namely rapid reversible changes in the tissue mechanical properties. These tissues are known as mutable collagenous tissues (MCTs). The mutability of these tissues has been the subject of on-going investigations, covering the biochemistry, structural biology and mechanical properties of the collagenous components. Recent studies point to a nerve-control system for regulating the ECM macromolecules that are involved in the sliding action of collagen fibrils in the MCT. This review discusses the key attributes of the structure and function of the ECM of the sea urchin ligaments that are related to the fibril-fibril sliding action-the focus is on the respective components within the hierarchical architecture of the tissue. In this context, structure refers to size, shape and separation distance of the ECM components while function is associated with mechanical properties e.g., strength and stiffness. For simplicity, the components that address the different length scale from the largest to the smallest are as follows: collagen fibres, collagen fibrils, interfibrillar matrix and collagen molecules. Application of recent theories of stress transfer and fracture mechanisms in fibre reinforced composites to a wide variety of collagen reinforcing (non-mutable) connective tissue, has allowed us to draw general conclusions concerning the mechanical response of the MCT at specific mechanical states, namely the stiff and complaint states. The intent of this review is to provide the latest insights, as well as identify technical challenges and opportunities, that may be useful for developing methods for effective mechanical support when adapting decellularised connective tissues from the sea urchin for tissue engineering or for the design of a synthetic analogue.
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Affiliation(s)
- Kheng Lim Goh
- Newcastle University Singapore, SIT Building at Nanyang Polytechnic, 172A Ang Mo Kio Avenue 8 #05-01, Singapore 567739, Singapore.
- Newcastle University, School of Mechanical & Systems Engineering, Stephenson Building, Claremont Road, Newcastle upon Tyne NE1 7RU, UK.
| | - David F Holmes
- Manchester University, Wellcome Trust Centre for Cell Matrix Research, B.3016 Michael Smith Building, Faculty of Life Sciences, Oxford Road, Manchester M13 9PT, UK.
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In situ mechanical and molecular investigations of collagen/apatite biomimetic composites combining Raman spectroscopy and stress-strain analysis. Acta Biomater 2016; 46:278-285. [PMID: 27667019 DOI: 10.1016/j.actbio.2016.09.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 09/14/2016] [Accepted: 09/22/2016] [Indexed: 01/29/2023]
Abstract
We report the design, fabrication and application of a novel micro-electromechanical device coupled to a confocal Raman microscope that enables in situ molecular investigations of micro-fibers under uniaxial tensile load. This device allows for the mechanical study of micro-fibers with diameters in the range between 10 and 100μm and lengths of several hundred micrometers. By exerting forces in the mN range, the device enables an important force range to be accessed between that of atomic force microscopy and macroscopic stress-strain measurement devices. The load is varied using a stiffness-calibrated glass micro-needle driven by a piezo-translator during simultaneous Raman microscopy imaging. The method enables experiments probing the molecular response of micro-fibers to external stress. This set-up was applied to biomimetic non-mineralized and mineralized collagen micro-fibers revealing that above 30% mineralization the proline-related Raman band shows a pronounced response to stress, which is not observed in non-mineralized collagen. This molecular response coincides with a strong increase in the Young's modulus from 0.5 to 6GPa for 0% and 70% mineralized collagen, respectively. Our results are consistent with a progressive interlocking of the collagen triple-helices by apatite nanocrystals as the degree of mineralization increases. STATEMENT OF SIGNIFICANCE Collagen and apatite are the main constituents regulating the mechanical properties of bone. Hence, an improved understanding of the impact of mineralization on these properties is of large interest for the scientific community. This paper presents systematic studies of synthetic collagen microfibers with increasing apatite content and their response to tensile stress by using a novel self-made electromechanical device combined with a Raman spectrometer for molecular level studies. The impact of apatite on the mechanical and molecular response of collagen is evaluated giving important insights into the interaction between the mineral and organic phases. Therefore our findings expand the fundamental understanding of the mechanics of the apatite/collagen system relevant for the design of bio-composites with similar bio-mimicking properties for e.g. bone regrowth in medical applications.
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Adouni M, Dhaher YY. A multi-scale elasto-plastic model of articular cartilage. J Biomech 2016; 49:2891-2898. [PMID: 27435568 DOI: 10.1016/j.jbiomech.2016.06.031] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 06/21/2016] [Accepted: 06/24/2016] [Indexed: 11/20/2022]
Abstract
Collagen damage is one of the earliest signs of cartilage degeneration and the onset of osteoarthritis (OA), but the connection between the microscale damage and macroscale tissue function is unclear. We argue that a multiscale model can help elucidate the biochemical and mechanical underpinnings of OA by connecting the microscale defects in collagen fibrils to the macroscopic cartilage mechanics. We investigated this connection using a multiscale fibril reinforced hyperelastoplastic (MFRHEP) model that accounts for the structural architecture of the soft tissue, starting from tropocollagen molecules that form fibrils, and moving to the complete soft tissue. This model was driven by reported experimental data from unconfined compression testing of cartilage. The model successfully described the observed transient response of the articular cartilage in unconfined and indentation tests with low and high loading rates. We used this model to understand damage initiation and propagation as a function of the cross-link density between tropocollagen molecules. This approach appeared to provide a realistic simulation of damage when compared with certain published studies. The current construct presents the first attempt to express the aggregate cartilage damage in terms of the cross-link density at the microfibril level.
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Affiliation(s)
- Malek Adouni
- Northwestern University, Physical Medicine and Rehabilitation Department, 345 East Superior Street, Chicago, IL 60611, USA; Rehabilitation Institute of Chicago, Sensory Motor Performance Program, 345 East Superior Street, Chicago, IL 60611, USA.
| | - Yasin Y Dhaher
- Northwestern University, Physical Medicine and Rehabilitation Department, 345 East Superior Street, Chicago, IL 60611, USA; Rehabilitation Institute of Chicago, Sensory Motor Performance Program, 345 East Superior Street, Chicago, IL 60611, USA; Northwestern University, Biomedical Engineering Department, 2145 Sheridan Road, Evanston, IL 60208, USA
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40
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Abstract
A brief overview of isolated collagen fibril mechanics testing is followed by presentation of the first results testing fibrils isolated from load-bearing mammalian tendons using a microelectromechanical systems platform. The in vitro modulus (326 ± 112 MPa) and fracture stress (71 ± 23 MPa) are shown to be lower than previously measured on fibrils extracted from sea cucumber dermis and tested with the same technique. Scanning electron microscope images show the fibrils can fail with a mechanism that involves circumferential rupture, whereas the core of the fibril stays at least partially intact.
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Affiliation(s)
- Yehe Liu
- Department of Biomedical Engineering , Case Western Reserve University , Cleveland, OH , USA
| | - Roberto Ballarini
- Department of Civil and Environmental Engineering , University of Houston , Houston, TX , USA
| | - Steven J Eppell
- Department of Biomedical Engineering , Case Western Reserve University , Cleveland, OH , USA
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Sabet FA, Raeisi Najafi A, Hamed E, Jasiuk I. Modelling of bone fracture and strength at different length scales: a review. Interface Focus 2016; 6:20150055. [PMID: 26855749 PMCID: PMC4686238 DOI: 10.1098/rsfs.2015.0055] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
In this paper, we review analytical and computational models of bone fracture and strength. Bone fracture is a complex phenomenon due to the composite, inhomogeneous and hierarchical structure of bone. First, we briefly summarize the hierarchical structure of bone, spanning from the nanoscale, sub-microscale, microscale, mesoscale to the macroscale, and discuss experimental observations on failure mechanisms in bone at these scales. Then, we highlight representative analytical and computational models of bone fracture and strength at different length scales and discuss the main findings in the context of experiments. We conclude by summarizing the challenges in modelling of bone fracture and strength and list open topics for scientific exploration. Modelling of bone, accounting for different scales, provides new and needed insights into the fracture and strength of bone, which, in turn, can lead to improved diagnostic tools and treatments of bone diseases such as osteoporosis.
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Affiliation(s)
| | | | | | - Iwona Jasiuk
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Feng Z, Ishiguro Y, Fujita K, Kosawada T, Nakamura T, Sato D, Kitajima T, Umezu M. A fibril-based structural constitutive theory reveals the dominant role of network characteristics on the mechanical behavior of fibroblast-compacted collagen gels. Biomaterials 2015; 67:365-81. [DOI: 10.1016/j.biomaterials.2015.07.038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 07/17/2015] [Accepted: 07/20/2015] [Indexed: 01/02/2023]
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Stender ME, Regueiro RA, Klisch SM, Ferguson VL. An Equilibrium Constitutive Model of Anisotropic Cartilage Damage to Elucidate Mechanisms of Damage Initiation and Progression. J Biomech Eng 2015; 137:081010. [DOI: 10.1115/1.4030744] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Indexed: 11/08/2022]
Abstract
Traumatic injuries and gradual wear-and-tear of articular cartilage (AC) that can lead to osteoarthritis (OA) have been hypothesized to result from tissue damage to AC. In this study, a previous equilibrium constitutive model of AC was extended to a constitutive damage articular cartilage (CDAC) model. In particular, anisotropic collagen (COL) fibril damage and isotropic glycosaminoglycan (GAG) damage were considered in a 3D formulation. In the CDAC model, time-dependent effects, such as viscoelasticity and poroelasticity, were neglected, and thus all results represent the equilibrium response after all time-dependent effects have dissipated. The resulting CDAC model was implemented in two different finite-element models. The first simulated uniaxial tensile loading to failure, while the second simulated spherical indentation with a rigid indenter displaced into a bilayer AC sample. Uniaxial tension to failure simulations were performed for three COL fibril Lagrangian failure strain (i.e., the maximum elastic COL fibril strain) values of 15%, 30%, and 45%, while spherical indentation simulations were performed with a COL fibril Lagrangian failure strain of 15%. GAG damage parameters were held constant for all simulations. Our results indicated that the equilibrium postyield tensile response of AC and the macroscopic tissue failure strain are highly dependent on COL fibril Lagrangian failure strain. The uniaxial tensile response consisted of an initial nonlinear ramp region due to the recruitment of intact fibrils followed by a rapid decrease in tissue stress at initial COL fibril failure, as a result of COL fibril damage which continued until ultimate tissue failure. In the spherical indentation simulation, damage to both the COL fibril and GAG constituents was located only in the superficial zone (SZ) and near the articular surface with tissue thickening following unloading. Spherical indentation simulation results are in agreement with published experimental observations. Our results indicate that the proposed CDAC model is capable of simulating both initial small magnitude damage as well as complete failure of AC tissue. The results of this study may help to elucidate the mechanisms of AC tissue damage, which initiate and propagate OA.
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Affiliation(s)
- Michael E. Stender
- Department of Mechanical Engineering, University of Colorado, Boulder, CO 80309
| | - Richard A. Regueiro
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado, Boulder, CO 80309
| | - Stephen M. Klisch
- Department of Mechanical Engineering, California Polytechnic State University, San Luis Obispo, CA 93407
| | - Virginia L. Ferguson
- Department of Mechanical Engineering, University of Colorado, 427 UCB, Boulder, CO 80309 e-mail:
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Zimmermann EA, Ritchie RO. Bone as a Structural Material. Adv Healthc Mater 2015; 4:1287-304. [PMID: 25865873 DOI: 10.1002/adhm.201500070] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 03/12/2015] [Indexed: 01/02/2023]
Abstract
As one of the most important natural materials, cortical bone is a composite material comprising assemblies of tropocollagen molecules and nanoscale hydroxyapatite mineral crystals, forming an extremely tough, yet lightweight, adaptive and multi-functional material. Bone has evolved to provide structural support to organisms, and therefore its mechanical properties are vital physiologically. Like many mineralized tissues, bone can resist deformation and fracture from the nature of its hierarchical structure, which spans molecular to macroscopic length-scales. In fact, bone derives its fracture resistance with a multitude of deformation and toughening mechanisms that are active at most of these dimensions. It is shown that bone's strength and ductility originate primarily at the scale of the nano to submicrometer structure of its mineralized collagen fibrils and fibers, whereas bone toughness is additionally generated at much larger, micro- to near-millimeter, scales from crack-tip shielding associated with interactions between the crack path and the microstructure. It is further shown how the effectiveness with which bone's structural features can resist fracture at small to large length-scales can become degraded by biological factors such as aging and disease, which affect such features as the collagen cross-linking environment, the homogeneity of mineralization, and the density of the osteonal structures.
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Affiliation(s)
| | - Robert O. Ritchie
- Materials Sciences Division; Lawrence Berkeley National Laboratory; Berkeley CA 94720 USA
- Department of Materials Science & Engineering; University of California; Berkeley CA 94720 USA
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Fessel G, Li Y, Diederich V, Guizar-Sicairos M, Schneider P, Sell DR, Monnier VM, Snedeker JG. Advanced glycation end-products reduce collagen molecular sliding to affect collagen fibril damage mechanisms but not stiffness. PLoS One 2014; 9:e110948. [PMID: 25364829 PMCID: PMC4217736 DOI: 10.1371/journal.pone.0110948] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 08/08/2014] [Indexed: 12/28/2022] Open
Abstract
Advanced glycation end-products (AGE) contribute to age-related connective tissue damage and functional deficit. The documented association between AGE formation on collagens and the correlated progressive stiffening of tissues has widely been presumed causative, despite the lack of mechanistic understanding. The present study investigates precisely how AGEs affect mechanical function of the collagen fibril--the supramolecular functional load-bearing unit within most tissues. We employed synchrotron small-angle X-ray scattering (SAXS) and carefully controlled mechanical testing after introducing AGEs in explants of rat-tail tendon using the metabolite methylglyoxal (MGO). Mass spectrometry and collagen fluorescence verified substantial formation of AGEs by the treatment. Associated mechanical changes of the tissue (increased stiffness and failure strength, decreased stress relaxation) were consistent with reports from the literature. SAXS analysis revealed clear changes in molecular deformation within MGO treated fibrils. Underlying the associated increase in tissue strength, we infer from the data that MGO modified collagen fibrils supported higher loads to failure by maintaining an intact quarter-staggered conformation to nearly twice the level of fibril strain in controls. This apparent increase in fibril failure resistance was characterized by reduced side-by-side sliding of collagen molecules within fibrils, reflecting lateral molecular interconnectivity by AGEs. Surprisingly, no change in maximum fibril modulus (2.5 GPa) accompanied the changes in fibril failure behavior, strongly contradicting the widespread assumption that tissue stiffening in ageing and diabetes is directly related to AGE increased fibril stiffness. We conclude that AGEs can alter physiologically relevant failure behavior of collagen fibrils, but that tissue level changes in stiffness likely occur at higher levels of tissue architecture.
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Affiliation(s)
- Gion Fessel
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Yufei Li
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Vincent Diederich
- Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
| | | | - Philipp Schneider
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
- Faculty of Engineering and the Environment, University of Southampton, Southampton, United Kingdom
| | - David R. Sell
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Vincent M. Monnier
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Jess G. Snedeker
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
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Connizzo BK, Sarver JJ, Han L, Soslowsky LJ. In situ fibril stretch and sliding is location-dependent in mouse supraspinatus tendons. J Biomech 2014; 47:3794-8. [PMID: 25468300 DOI: 10.1016/j.jbiomech.2014.10.029] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 10/15/2014] [Accepted: 10/21/2014] [Indexed: 12/27/2022]
Abstract
Tendons are able to transmit high loads efficiently due to their finely optimized hierarchical collagen structure. Two mechanisms by which tendons respond to load are collagen fibril sliding and deformation (stretch). Although many studies have demonstrated that regional variations in tendon structure, composition, and organization contribute to the full tendon׳s mechanical response, the location-dependent response to loading at the fibril level has not been investigated. In addition, the instantaneous response of fibrils to loading, which is clinically relevant for repetitive stretch or fatigue injuries, has also not been studied. Therefore, the purpose of this study was to quantify the instantaneous response of collagen fibrils throughout a mechanical loading protocol, both in the insertion site and in the midsubstance of the mouse supraspinatus tendon. Utilizing a novel atomic force microscopy-based imaging technique, tendons at various strain levels were directly visualized and analyzed for changes in fibril d-period with increasing tendon strain. At the insertion site, d-period significantly increased from 0% to 1% tendon strain, increased again from 3% to 5% strain, and decreased after 5% strain. At the midsubstance, d-period increased from 0% to 1% strain and then decreased after 7% strain. In addition, fibril d-period heterogeneity (fibril sliding) was present, primarily at 3% strain with a large majority occurring in the tendon midsubstance. This study builds upon previous work by adding information on the instantaneous and regional-dependent fibrillar response to mechanical loading and presents data proposing that collagen fibril sliding and stretch are directly related to tissue organization and function.
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Affiliation(s)
- Brianne K Connizzo
- McKay Orthopaedic Research Laboratory, University of Pennsylvania, 424 Stemmler Hall, 36th and Hamilton Walk, Philadelphia, PA, 19104
| | - Joseph J Sarver
- McKay Orthopaedic Research Laboratory, University of Pennsylvania, 424 Stemmler Hall, 36th and Hamilton Walk, Philadelphia, PA, 19104; School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut Street, Philadelphia, PA, 19104
| | - Lin Han
- School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut Street, Philadelphia, PA, 19104
| | - Louis J Soslowsky
- McKay Orthopaedic Research Laboratory, University of Pennsylvania, 424 Stemmler Hall, 36th and Hamilton Walk, Philadelphia, PA, 19104.
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Zhou Z, Minary-Jolandan M, Qian D. A simulation study on the significant nanomechanical heterogeneous properties of collagen. Biomech Model Mechanobiol 2014; 14:445-57. [DOI: 10.1007/s10237-014-0615-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 09/01/2014] [Indexed: 10/24/2022]
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Kwan K, Cranford SW. Quantifying Cooperativity via Geometric Gyration-Based Metrics of Coupled Macromolecules. JOURNAL OF NANOMECHANICS AND MICROMECHANICS 2014. [DOI: 10.1061/(asce)nm.2153-5477.0000095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Affiliation(s)
- Kenny Kwan
- Graduate Research Assistant, Laboratory of Nanotechnology in Civil Engineering, Dept. of Civil and Environmental Engineering, Northeastern Univ., Boston, MA 02115
| | - Steven W. Cranford
- Assistant Professor, Laboratory of Nanotechnology in Civil Engineering, Dept. of Civil and Environmental Engineering, Northeastern Univ., Boston, MA 02115 (corresponding author)
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Szczesny SE, Elliott DM. Interfibrillar shear stress is the loading mechanism of collagen fibrils in tendon. Acta Biomater 2014; 10:2582-90. [PMID: 24530560 DOI: 10.1016/j.actbio.2014.01.032] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 12/04/2013] [Accepted: 01/30/2014] [Indexed: 12/15/2022]
Abstract
Despite the critical role tendons play in transmitting loads throughout the musculoskeletal system, little is known about the microstructural mechanisms underlying their mechanical function. Of particular interest is whether collagen fibrils in tendon fascicles bear load independently or if load is transferred between fibrils through interfibrillar shear forces. We conducted multiscale experimental testing and developed a microstructural shear lag model to explicitly test whether interfibrillar shear load transfer is indeed the fibrillar loading mechanism in tendon. Experimental correlations between fascicle macroscale mechanics and microscale interfibrillar sliding suggest that fibrils are discontinuous and share load. Moreover, for the first time, we demonstrate that a shear lag model can replicate the fascicle macroscale mechanics as well as predict the microscale fibrillar deformations. Since interfibrillar shear stress is the fundamental loading mechanism assumed in the model, this result provides strong evidence that load is transferred between fibrils in tendon and possibly other aligned collagenous tissues. Conclusively establishing this fibrillar loading mechanism and identifying the involved structural components should help develop repair strategies for tissue degeneration and guide the design of tissue engineered replacements.
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Affiliation(s)
- Spencer E Szczesny
- Department of Bioengineering, University of Pennsylvania, 240 Skirkanich Hall, 210 South 33rd St, Philadelphia, PA 19104, USA
| | - Dawn M Elliott
- Department of Biomedical Engineering, University of Delaware, 125 East Delaware Avenue, Newark, DE 19716, USA.
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