1
|
Watanabe C, Zhong J, Yamashita S, Kondo Y, Masaki C, Hosokawa R, Shibata Y. Mechanical insights into jawbone characteristics under chronic kidney disease: A comprehensive nanoindentation approach. J Mech Behav Biomed Mater 2024; 154:106506. [PMID: 38518511 DOI: 10.1016/j.jmbbm.2024.106506] [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: 12/21/2023] [Revised: 03/09/2024] [Accepted: 03/11/2024] [Indexed: 03/24/2024]
Abstract
The mechanical properties of the jawbone play a critical role in determining the successful integration of dental prostheses. Chronic kidney disease (CKD) has been identified to abnormally accelerate bone turnover rates. However, the impact of CKD on the mechanical characteristics of the jawbone has not been extensively studied. This study sought to evaluate the time-dependent viscoelastic behaviors of rat jawbones, particularly in the scenarios both with and without CKD. We hypothesized that CKD might compromise the bone's innate toughening mechanisms, potentially owing to the time-dependent viscoelasticity of the bone matrix proteins. The maxillary and mandibular bones of Wistar rats were subjected to nanoindentation and Raman micro-spectroscopy. Load-hold-displacement curves from the cortical regions were obtained via nanoindentation and were mathematically characterized using a suitable viscoelastic constitutive model. Raman micro-spectroscopy was employed to identify nuanced vibrational changes in local molecular structures induced by CKD. The time course of indenter penetration onto cortical bones during the holding stage (creep behavior) can be mathematically represented by a series arrangement of the Kelvin-Voigt bodies. This configuration dictates the overall viscoelastic response observed during nanoindentation tests. The CKD model exhibited a reduced extent of viscoelastic contributions, especially during the initial ramp loading phase in both the maxillary and mandibular cortical bones. The generalized Kelvin-Voigt model comprises 2 K-Voigt elements that signify an immediate short retardation time (τ1) and a subsequent prolonged retardation time (τ2), respectively. Notably, the mandibular CKD model led to an increase in the delayed τ2 alongside an increase in non-enzymatic collagen cross-linking. These suggest that, over time, CKD diminishes the bone's capability for supplementary energy absorption and dimensional recovery, thus heightening their susceptibility to fractures.
Collapse
Affiliation(s)
- Chie Watanabe
- Department of Biomaterials and Engineering, Showa University School of Dentistry, Tokyo, Japan.
| | - Jingxiao Zhong
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, Australia
| | - Sotaro Yamashita
- Division of Oral Reconstruction and Rehabilitation, Kyusyu Dental University, Kitakyushu, Japan
| | - Yusuke Kondo
- Division of Oral Reconstruction and Rehabilitation, Kyusyu Dental University, Kitakyushu, Japan
| | - Chihiro Masaki
- Division of Oral Reconstruction and Rehabilitation, Kyusyu Dental University, Kitakyushu, Japan
| | - Ryuji Hosokawa
- Division of Oral Reconstruction and Rehabilitation, Kyusyu Dental University, Kitakyushu, Japan
| | - Yo Shibata
- Department of Biomaterials and Engineering, Showa University School of Dentistry, Tokyo, Japan
| |
Collapse
|
2
|
Xi Y, Deng X, Shu Z, Yang C. Probing nanoscale structural response of collagen fibril in human Achilles tendon during loading using in situ SAXS. J Mech Behav Biomed Mater 2024; 156:106599. [PMID: 38820710 DOI: 10.1016/j.jmbbm.2024.106599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 05/17/2024] [Accepted: 05/23/2024] [Indexed: 06/02/2024]
Abstract
The specific viscoelastic mechanical properties of the human Achilles tendon are strongly dependent on the structural characteristics of collagen. Although research on the deformation mechanisms of the Achilles tendon in various animals is extensive, understanding of these mechanisms in the human Achilles tendon remains largely empirical and macroscopic. In this work, the evolution of D-space, orientation, and average length of voids between fibers are investigated during the stretching using SAXS techniques. Initially, the void length increases marginally, while the misorientation breadth decreased rapidly as the D-space steadily increased. In the second region, D-space and the void length increase sharply under rising stress, even though misorientation width decreased. During the third region, the increases in void length and D-space decelerate, but the misorientation width widens, suggesting the onset of irreversible microscopic fibril failure in the Achilles tendon. In the final region, the fibers undergo macroscopic failure, with D-space and void length returning to their initial states. The macroscopic alterations are elucidated by the nanoscale structural responses, providing a fundamental understanding of the mechanisms driving the complex biomechanics, tissue structural organization, and Achilles tendon regeneration.
Collapse
Affiliation(s)
- Yan Xi
- Department of Radiology, Shanghai TCM-Integrated Hospital, Shanghai University of TCM, 200082, China
| | - Xiaofei Deng
- Department of Radiology, Shanghai TCM-Integrated Hospital, Shanghai University of TCM, 200082, China.
| | - Zheng Shu
- Department of Radiology, Shanghai TCM-Integrated Hospital, Shanghai University of TCM, 200082, China.
| | - Chunming Yang
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201204, China.
| |
Collapse
|
3
|
Gallagher S, Josyula K, Rahul, Kruger U, Gong A, Song A, Eschelbach E, Crawford D, Pham T, Sweet R, Parsey C, Norfleet J, De S. Mechanical behavior of full-thickness burn human skin is rate-independent. Sci Rep 2024; 14:11096. [PMID: 38750077 PMCID: PMC11096406 DOI: 10.1038/s41598-024-61556-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 05/07/2024] [Indexed: 05/18/2024] Open
Abstract
Skin tissue is recognized to exhibit rate-dependent mechanical behavior under various loading conditions. Here, we report that the full-thickness burn human skin exhibits rate-independent behavior under uniaxial tensile loading conditions. Mechanical properties, namely, ultimate tensile stress, ultimate tensile strain, and toughness, and parameters of Veronda-Westmann hyperelastic material law were assessed via uniaxial tensile tests. Univariate hypothesis testing yielded no significant difference (p > 0.01) in the distributions of these properties for skin samples loaded at three different rates of 0.3 mm/s, 2 mm/s, and 8 mm/s. Multivariate multiclass classification, employing a logistic regression model, failed to effectively discriminate samples loaded at the aforementioned rates, with a classification accuracy of only 40%. The median values for ultimate tensile stress, ultimate tensile strain, and toughness are computed as 1.73 MPa, 1.69, and 1.38 MPa, respectively. The findings of this study hold considerable significance for the refinement of burn care training protocols and treatment planning, shedding new light on the unique, rate-independent behavior of burn skin.
Collapse
Grants
- W911NF-17-2-0022 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W911NF-17-2-0022 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W911NF-17-2-0022 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W911NF-17-2-0022 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W912CG-20-2-0004 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W912CG-20-2-0004 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W912CG-20-2-0004 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W912CG-20-2-0004 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W912CG-20-2-0004 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W912CG-20-2-0004 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W911NF-17-2-0022 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
Collapse
Affiliation(s)
- Samara Gallagher
- Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
- Center for Modeling, Simulation, and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Kartik Josyula
- Center for Modeling, Simulation, and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Rahul
- Center for Modeling, Simulation, and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, NY, USA.
| | - Uwe Kruger
- Center for Modeling, Simulation, and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, NY, USA
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Alex Gong
- Center for Research in Education and Simulation Technologies, University of Washington, Seattle, WA, USA
| | - Agnes Song
- Center for Research in Education and Simulation Technologies, University of Washington, Seattle, WA, USA
| | - Emily Eschelbach
- UW Medicine Regional Burn Center at Harborview Medical Center, University of Washington, Seattle, WA, USA
| | - David Crawford
- UW Medicine Regional Burn Center at Harborview Medical Center, University of Washington, Seattle, WA, USA
| | - Tam Pham
- UW Medicine Regional Burn Center at Harborview Medical Center, University of Washington, Seattle, WA, USA
| | - Robert Sweet
- Center for Research in Education and Simulation Technologies, University of Washington, Seattle, WA, USA
| | - Conner Parsey
- U.S. Army Combat Capabilities Development Command - Soldier Center, Simulation and Training Technology Center, Orlando, FL, USA
| | - Jack Norfleet
- U.S. Army Combat Capabilities Development Command - Soldier Center, Simulation and Training Technology Center, Orlando, FL, USA
| | - Suvranu De
- Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
- Center for Modeling, Simulation, and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, NY, USA
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
| |
Collapse
|
4
|
Dremin V, Zharkikh E, Lopushenko I, Marcinkevics Z, Bykov A, Meglinski I. Incremental residual polarization caused by aging in human skin. JOURNAL OF BIOMEDICAL OPTICS 2024; 29:052912. [PMID: 38077500 PMCID: PMC10704186 DOI: 10.1117/1.jbo.29.5.052912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 09/01/2023] [Accepted: 10/19/2023] [Indexed: 12/18/2023]
Abstract
Significance The study of the effect of aging on the optical properties of biological tissues, in particular polarization, is important in the development of new diagnostic approaches. Aim This work aims to provide a comprehensive analysis of the factors and mechanisms that contribute to the alteration of skin polarization properties caused by aging, using polarization-sensitive hyperspectral imaging measurements and Monte Carlo simulation. Approach Our investigation involved both experimental studies of in vivo human skin of volunteers of different ages and computational modeling that accounted for changes in the absorption and scattering properties of the skin model. Specifically, we analyzed alterations in the degree of linear polarization (DOLP) to better understand the impact of aging on skin polarization properties. Results A statistically significant increase in the DOLP was found for the elderly group. At the same time, there was no correlation between changes in polarization and the calculated blood volume fraction parameter for different ages. According to the simulation results, it was also found that a change in the scattering properties of biological tissues has a more significant effect on the change in polarizing light compared to the change in absorption. Conclusions The results of the work prove that the sensitivity of polarization imaging to age- or pathological-related skin changes may be primarily due to changes in scattering, which in turn is associated with changes in the collagen fibers of the dermis. The proposed technique shows promise for in vivo non-invasive real-time assessment of age-associated skin changes and can also be extended to monitor changes associated with the development of age-related pathologies.
Collapse
Affiliation(s)
- Viktor Dremin
- University of Oulu, Opto-Electronics and Measurement Techniques Unit, Faculty of Information Technology and Electrical Engineering, Oulu, Finland
- Aston University, College of Engineering and Physical Sciences, Birmingham, United Kingdom
| | - Elena Zharkikh
- University of Oulu, Opto-Electronics and Measurement Techniques Unit, Faculty of Information Technology and Electrical Engineering, Oulu, Finland
| | - Ivan Lopushenko
- University of Oulu, Opto-Electronics and Measurement Techniques Unit, Faculty of Information Technology and Electrical Engineering, Oulu, Finland
| | | | - Alexander Bykov
- University of Oulu, Opto-Electronics and Measurement Techniques Unit, Faculty of Information Technology and Electrical Engineering, Oulu, Finland
| | - Igor Meglinski
- University of Oulu, Opto-Electronics and Measurement Techniques Unit, Faculty of Information Technology and Electrical Engineering, Oulu, Finland
- Aston University, College of Engineering and Physical Sciences, Birmingham, United Kingdom
- I.M. Sechenov First Moscow State Medical University, Human Anatomy and Histology Department, N.V. Sklifosovsky Institute of Clinical Medicine, Moscow, Russia
| |
Collapse
|
5
|
Jansen I, Cahalane R, Hengst R, Akyildiz A, Farrell E, Gijsen F, Aikawa E, van der Heiden K, Wissing T. The interplay of collagen, macrophages, and microcalcification in atherosclerotic plaque cap rupture mechanics. Basic Res Cardiol 2024; 119:193-213. [PMID: 38329498 PMCID: PMC11008085 DOI: 10.1007/s00395-024-01033-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 01/17/2024] [Accepted: 01/19/2024] [Indexed: 02/09/2024]
Abstract
The rupture of an atherosclerotic plaque cap overlying a lipid pool and/or necrotic core can lead to thrombotic cardiovascular events. In essence, the rupture of the plaque cap is a mechanical event, which occurs when the local stress exceeds the local tissue strength. However, due to inter- and intra-cap heterogeneity, the resulting ultimate cap strength varies, causing proper assessment of the plaque at risk of rupture to be lacking. Important players involved in tissue strength include the load-bearing collagenous matrix, macrophages, as major promoters of extracellular matrix degradation, and microcalcifications, deposits that can exacerbate local stress, increasing tissue propensity for rupture. This review summarizes the role of these components individually in tissue mechanics, along with the interplay between them. We argue that to be able to improve risk assessment, a better understanding of the effect of these individual components, as well as their reciprocal relationships on cap mechanics, is required. Finally, we discuss potential future steps, including a holistic multidisciplinary approach, multifactorial 3D in vitro model systems, and advancements in imaging techniques. The obtained knowledge will ultimately serve as input to help diagnose, prevent, and treat atherosclerotic cap rupture.
Collapse
Affiliation(s)
- Imke Jansen
- Department of Biomedical Engineering, Thorax Center Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Rachel Cahalane
- Mechanobiology and Medical Device Research Group (MMDRG), Biomedical Engineering, College of Science and Engineering, University of Galway, Galway, Ireland
- Division of Cardiovascular Medicine, Department of Medicine, Center for Interdisciplinary Cardiovascular Sciences Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Ranmadusha Hengst
- Department of Biomedical Engineering, Thorax Center Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Ali Akyildiz
- Department of Biomedical Engineering, Thorax Center Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
- Biomechanical Engineering, Technical University Delft, Delft, The Netherlands
| | - Eric Farrell
- Department of Oral and Maxillofacial Surgery, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Frank Gijsen
- Department of Biomedical Engineering, Thorax Center Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
- Biomechanical Engineering, Technical University Delft, Delft, The Netherlands
| | - Elena Aikawa
- Division of Cardiovascular Medicine, Department of Medicine, Center for Interdisciplinary Cardiovascular Sciences Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Kim van der Heiden
- Department of Biomedical Engineering, Thorax Center Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Tamar Wissing
- Department of Biomedical Engineering, Thorax Center Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands.
| |
Collapse
|
6
|
Deymier AC, Deymier PA. Open-system force-elongation relationship of collagen in chemo-mechanical equilibrium with water. J Mech Behav Biomed Mater 2024; 152:106464. [PMID: 38367533 DOI: 10.1016/j.jmbbm.2024.106464] [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: 08/21/2023] [Revised: 02/07/2024] [Accepted: 02/13/2024] [Indexed: 02/19/2024]
Abstract
A significant deformation mechanism of collagen at low loads is molecular uncoiling and rearrangement. Although the effect of hydration and cross-linking has been investigated at larger loads when collagen undergoes molecular sliding, their effects on collagen molecular reorganization remain unclear. Here we develop two thermodynamic models that use the notion of open-system elasticity to elucidate the effect of swelling due to water uptake during deformation of collagen networks under low and high cross-linking conditions. With low crosslinking, entropic contributions dominate resulting in rejection of solvent from the polymer network leading to reduced collagen stiffness with increased loads. Contrarily, high cross-linking inhibits initial coiling and structural kinking and the mechanical behavior is dominated by elastic energy. In this configuration, the solvent content depends on the sign of the applied load resulting in a non-linear open-system stress-strain relationship. The models provide insight on the parameters that impact the stress-strain relationships of hydrated collagen and can inform the way collagenous matrices are treated both in medical and laboratory settings.
Collapse
Affiliation(s)
- A C Deymier
- Department of Biomedical Engineering, UConn Health, Farmington, CT, USA.
| | - P A Deymier
- Department of Materials Science and Engineering, University of Arizona, Tucson, AZ, 85721, USA
| |
Collapse
|
7
|
Feng W, Wang L, Liu CJ, Zhang C. Skin characterization of diabetes mellitus revealed by polarization-sensitive optical coherence tomography imaging. JOURNAL OF BIOMEDICAL OPTICS 2024; 29:036003. [PMID: 38481479 PMCID: PMC10933388 DOI: 10.1117/1.jbo.29.3.036003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 01/18/2024] [Accepted: 02/28/2024] [Indexed: 03/24/2024]
Abstract
Significance Diabetes can lead to the glycation of proteins and dysfunction of skin collagen. Skin lesions are a prevalent clinical symptom of diabetes mellitus (DM). Early diagnosis and assessing the efficacy of treatment for DM are crucial for patient health management. However, performing a non-invasive skin assessment in the early stages of DM is challenging. Aim By using the polarization-sensitive optical coherent tomography (PS-OCT) imaging technique, it is possible to noninvasively assess the skin changes caused by diabetes. Approach The PS-OCT was used to monitor the polarization characteristics of mouse skin at different stages of diabetes. Results Based on a multi-layered adhesive tape model, we found that the polarization characteristics (retardation, optic axis, and polarization uniformity) were sensitive to the microstructure changes in the samples. Through this method, we observed significant changes in the polarization states of the skin as diabetes progressed. This was in line with the detected microstructure changes in skin collagen fibers using scanning electron microscopy. Conclusions This study presents a highly useful approach for non-invasive skin assessment of diabetes.
Collapse
Affiliation(s)
- Wei Feng
- Central People's Hospital of Zhanjiang, Zhanjiang Institute of Clinical Medicine, Zhanjiang, China
- Zhanjiang Central Hospital, Guangdong Medical University, Zhanjiang, China
| | - Lisi Wang
- Central People's Hospital of Zhanjiang, Zhanjiang Institute of Clinical Medicine, Zhanjiang, China
- Zhanjiang Central Hospital, Guangdong Medical University, Zhanjiang, China
| | - Chun-Jie Liu
- Huazhong University of Science and Technology, College of Life Science and Technology, Center for Artificial Intelligence Biology, Hubei Bioinformatics & Molecular Imaging Key Laboratory, Key Laboratory of Molecular Biophysics of the Ministry of Education, Wuhan, China
| | - Chao Zhang
- Central People's Hospital of Zhanjiang, Zhanjiang Institute of Clinical Medicine, Zhanjiang, China
- Zhanjiang Central Hospital, Guangdong Medical University, Zhanjiang, China
| |
Collapse
|
8
|
Noh S, Lee SJ, Yoo JJ, Jin YJ, Yun HW, Min BH, Park JY, Park DY. Synovium-Derived Mesenchymal Stem Cell-Based Scaffold-Free Fibrocartilage Engineering for Bone-Tendon Interface Healing in an Anterior Cruciate Ligament Reconstruction Model. Tissue Eng Regen Med 2024; 21:341-351. [PMID: 37856071 PMCID: PMC10825091 DOI: 10.1007/s13770-023-00593-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 08/21/2023] [Accepted: 08/27/2023] [Indexed: 10/20/2023] Open
Abstract
BACKGROUND Current tendon and ligament reconstruction surgeries rely on scar tissue healing which differs from native bone-to-tendon interface (BTI) tissue. We aimed to engineer Synovium-derived mesenchymal stem cells (Sy-MSCs) based scaffold-free fibrocartilage constructs and investigate in vivo bone-tendon interface (BTI) healing efficacy in a rat anterior cruciate ligament (ACL) reconstruction model. METHODS Sy-MSCs were isolated from knee joint of rats. Scaffold-free sy-MSC constructs were fabricated and cultured in differentiation media including TGF-β-only, CTGF-only, and TGF-β + CTGF. Collagenase treatment on tendon grafts was optimized to improve cell-to-graft integration. The effects of fibrocartilage differentiation and collagenase treatment on BTI integration was assessed by conducting histological staining, cell adhesion assay, and tensile testing. Finally, histological and biomechanical analyses were used to evaluate in vivo efficacy of fibrocartilage construct in a rat ACL reconstruction model. RESULTS Fibrocartilage-like features were observed with in the scaffold-free sy-MSC constructs when applying TGF-β and CTGF concurrently. Fifteen minutes collagenase treatment increased cellular attachment 1.9-fold compared to the Control group without affecting tensile strength. The failure stress was highest in the Col + D + group (22.494 ± 13.74 Kpa) compared to other groups at integration analysis in vitro. The ACL Recon + FC group exhibited a significant 88% increase in estimated stiffness (p = 0.0102) compared to the ACL Recon group at the 4-week postoperative period. CONCLUSION Scaffold-free, fibrocartilage engineering together with tendon collagenase treatment enhanced fibrocartilaginous BTI healing in ACL reconstruction.
Collapse
Affiliation(s)
- Sujin Noh
- Department of Biomedical Sciences, Graduate School of Ajou University, 206 World Cup-Ro, Yeongtong-Gu, Suwon, Republic of Korea
| | - Sang Jin Lee
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA
| | - James J Yoo
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA
| | - Yong Jun Jin
- Department of Orthopedic Surgery, School of Medicine, Ajou University, Suwon, Republic of Korea
| | - Hee-Woong Yun
- Cell Therapy Center, Ajou Medical Center, Suwon, Republic of Korea
| | - Byoung-Hyun Min
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA
| | - Jae-Young Park
- Department of Orthopedics Surgery, CHA University Bundang Medical Center, Bundang-Gu, Seongnam-Si, Gyeonggi-Do, Republic of Korea
| | - Do Young Park
- Department of Biomedical Sciences, Graduate School of Ajou University, 206 World Cup-Ro, Yeongtong-Gu, Suwon, Republic of Korea.
- Department of Orthopedic Surgery, School of Medicine, Ajou University, Suwon, Republic of Korea.
- Cell Therapy Center, Ajou Medical Center, Suwon, Republic of Korea.
- Leading Convergence of Healthcare and Medicine, Institute of Science & Technology (ALCHeMIST), Ajou University, Suwon, Republic of Korea.
| |
Collapse
|
9
|
Mohammadkhah M, Klinge S. Review paper: The importance of consideration of collagen cross-links in computational models of collagen-based tissues. J Mech Behav Biomed Mater 2023; 148:106203. [PMID: 37879165 DOI: 10.1016/j.jmbbm.2023.106203] [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: 06/23/2023] [Revised: 09/25/2023] [Accepted: 10/17/2023] [Indexed: 10/27/2023]
Abstract
Collagen as the main protein in Extra Cellular Matrix (ECM) is the main load-bearing component of fibrous tissues. Nanostructure and architecture of collagen fibrils play an important role in mechanical behavior of these tissues. Extensive experimental and theoretical studies have so far been performed to capture these properties, but none of the current models realistically represent the complexity of network mechanics because still less is known about the collagen's inner structure and its effect on the mechanical properties of tissues. The goal of this review article is to emphasize the significance of cross-links in computational modeling of different collagen-based tissues, and to reveal the need for continuum models to consider cross-links properties to better reflect the mechanical behavior observed in experiments. In addition, this study outlines the limitations of current investigations and provides potential suggestions for the future work.
Collapse
Affiliation(s)
- Melika Mohammadkhah
- Technische Universität Berlin, Institute of Mechanics, Chair of Structural Mechanics and Analysis, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany.
| | - Sandra Klinge
- Technische Universität Berlin, Institute of Mechanics, Chair of Structural Mechanics and Analysis, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
| |
Collapse
|
10
|
McCabe MC, Okamura DM, Erickson CB, Perry BW, Brewer CM, Nguyen ED, Saviola AJ, Majesky MW, Hansen KC. ECM-Focused Proteomic Analysis of Ear Punch Regeneration in Acomys Cahirinus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.11.561940. [PMID: 37873317 PMCID: PMC10592745 DOI: 10.1101/2023.10.11.561940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
In mammals, significant injury is generally followed by the formation of a fibrotic scar which provides structural integrity but fails to functionally restore damaged tissue. Spiny mice of the genus Acomys represent the first example of full skin autotomy in mammals. Acomys cahirinus has evolved extremely weak skin as a strategy to avoid predation and is able to repeatedly regenerate healthy tissue without scar after severe skin injury or full-thickness ear punches. Extracellular matrix (ECM) composition is a critical regulator of wound repair and scar formation and previous studies have suggested that alterations in its expression may be responsible for the differences in regenerative capacity observed between Mus musculus and A. cahirinus , yet analysis of this critical tissue component has been limited in previous studies by its insolubility and resistance to extraction. Here, we utilize a 2-step ECM-optimized extraction to perform proteomic analysis of tissue composition during wound repair after full-thickness ear punches in A. cahirinus and M. musculus from weeks 1 to 4 post-injury. We observe changes in a wide range of ECM proteins which have been previously implicated in wound regeneration and scar formation, including collagens, coagulation and provisional matrix proteins, and matricryptic signaling peptides. We additionally report differences in crosslinking enzyme activity and ECM protein solubility between Mus and Acomys. Furthermore, we observed rapid and sustained increases in CD206, a marker of pro-regenerative M2 macrophages, in Acomys, whereas little or no increase in CD206 was detected in Mus. Together, these findings contribute to a comprehensive understanding of tissue cues which drive the regenerative capacity of Acomys and identify a number of potential targets for future pro-regenerative therapies.
Collapse
|
11
|
Wohlgemuth RP, Brashear SE, Smith LR. Alignment, cross linking, and beyond: a collagen architect's guide to the skeletal muscle extracellular matrix. Am J Physiol Cell Physiol 2023; 325:C1017-C1030. [PMID: 37661921 PMCID: PMC10635663 DOI: 10.1152/ajpcell.00287.2023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 08/27/2023] [Accepted: 08/27/2023] [Indexed: 09/05/2023]
Abstract
The muscle extracellular matrix (ECM) forms a complex network of collagens, proteoglycans, and other proteins that produce a favorable environment for muscle regeneration, protect the sarcolemma from contraction-induced damage, and provide a pathway for the lateral transmission of contractile force. In each of these functions, the structure and organization of the muscle ECM play an important role. Many aspects of collagen architecture, including collagen alignment, cross linking, and packing density affect the regenerative capacity, passive mechanical properties, and contractile force transmission pathways of skeletal muscle. The balance between fortifying the muscle ECM and maintaining ECM turnover and compliance is highly dependent on the integrated organization, or architecture, of the muscle matrix, especially related to collagen. While muscle ECM remodeling patterns in response to exercise and disease are similar, in that collagen synthesis can increase in both cases, one outcome leads to a stronger muscle and the other leads to fibrosis. In this review, we provide a comprehensive analysis of the architectural features of each layer of muscle ECM: epimysium, perimysium, and endomysium. Further, we detail the importance of muscle ECM architecture to biomechanical function in the context of exercise or fibrosis, including disease, injury, and aging. We describe how collagen architecture is linked to active and passive muscle biomechanics and which architectural features are acutely dynamic and adapt over time. Future studies should investigate the significance of collagen architecture in muscle stiffness, ECM turnover, and lateral force transmission in the context of health and fibrosis.
Collapse
Affiliation(s)
- Ross P Wohlgemuth
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California, United States
| | - Sarah E Brashear
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California, United States
| | - Lucas R Smith
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California, United States
- Department of Physical Medicine and Rehabilitation, University of California, Davis, California, United States
| |
Collapse
|
12
|
Szczesny SE, Corr DT. Tendon cell and tissue culture: Perspectives and recommendations. J Orthop Res 2023; 41:2093-2104. [PMID: 36794495 DOI: 10.1002/jor.25532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/19/2023] [Accepted: 02/08/2023] [Indexed: 02/17/2023]
Abstract
The wide variety of cell and tissue culture systems used to study and engineer tendons can make it difficult to choose the best approach and "optimal" culture conditions to test a given hypothesis. Therefore, a breakout session was organized at the 2022 ORS Tendon Section Meeting that focused on establishing a set of guidelines for conducting cell and tissue culture studies of tendon. This paper summarizes the outcomes of that discussion and presents recommendations for future studies. In the case of studying tendon cell behavior, cell and tissue culture systems are reductionist models in which the culture conditions should be strictly defined to approximate the in vivo condition as closely as possible. In contrast, for tissue engineering tendon replacements, the culture conditions do not need to replicate native tendon, but the outcome measures for success should be narrowly defined for the specific clinical application. Common recommendations for both applications are that researchers should perform a baseline phenotypic characterization of the cells that are ultimately used for experimentation. For models of tendon cell behavior, culture conditions should be well justified by existing literature and meticulously reported, tissue explant viability should be assessed, and comparisons to in vivo conditions should be made to determine baseline physiological relevance. For tissue engineering applications, the functional/structural/compositional outcome targets should be defined by the specific tendons they seek to replace, with key biologic and material properties prioritized for construct assessment. Lastly, when engineering tendon replacements, researchers should utilize clinically approved cGMP materials to facilitate clinical translation.
Collapse
Affiliation(s)
- Spencer E Szczesny
- Department of Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania, USA
- Department of Orthopaedics and Rehabilitation, Pennsylvania State University, Hershey, Pennsylvania, USA
| | - David T Corr
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA
| |
Collapse
|
13
|
Anderl WJ, Pearson N, Converse MI, Yu SM, Monson KL. Strain-induced collagen denaturation is rate dependent in failure of cerebral arteries. Acta Biomater 2023; 164:282-292. [PMID: 37116635 DOI: 10.1016/j.actbio.2023.04.032] [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: 10/29/2022] [Revised: 04/06/2023] [Accepted: 04/21/2023] [Indexed: 04/30/2023]
Abstract
While soft tissues are commonly damaged by mechanical loading, the manifestation of this damage at the microstructural level is not fully understood. Specifically, while rate-induced stiffening has been previously observed in cerebral arteries, associated changes in microstructural damage patterns following high-rate loading are largely undefined. In this study, we stretched porcine middle cerebral arteries to failure at 0.01 and >150 s-1, both axially and circumferentially, followed by probing for denatured tropocollagen using collagen hybridizing peptide (CHP). We found that collagen fibrils aligned with the loading direction experienced less denaturation following failure tests at high than low rates. Others have demonstrated similar rate dependence in tropocollagen denaturation during soft tissue failure, but this is the first study to quantify this behavior using CHP and to report it for cerebral arteries. These findings may have significant implications for traumatic brain injury and intracranial balloon angioplasty. We additionally observed possible tropocollagen denaturation in vessel layers primarily composed of fibrils transversely aligned to the loading axis. To our knowledge, this is the first observation of collagen denaturation due to transverse loading, but further research is needed to confirm this finding. STATEMENT OF SIGNIFICANCE: Previous work shows that collagen hybridizing peptide (CHP) can be used to identify collagen molecule unfolding and denaturation in mechanically overloaded soft tissues, including the cerebral arteries. But experiments have not explored collagen damage at rates relevant to traumatic brain injury. In this work, we quantified collagen damage in cerebral arteries stretched to failure at both high and low rates. We found that the collagen molecule is less damaged at high than at low rates, suggesting that damage mechanisms of either the collagen molecule or other elements of the collagen superstructure are rate dependent. This work implies that arteries failed at high rates, such as in traumatic brain injury, will have different molecular-level damage patterns than arteries failed at low rates. Consequently, improved understanding of damage characteristics may be expanded in the future to better inform clinically relevant cases of collagen damage such as angioplasty and injury healing.
Collapse
Affiliation(s)
| | - Noah Pearson
- DepSSSartment of Mechanical Engineering, University of Utah
| | | | - S Michael Yu
- Department of Biomedical Engineering, University of Utah; Department of Molecular Pharmaceutics, University of Utah
| | - Kenneth L Monson
- DepSSSartment of Mechanical Engineering, University of Utah; Department of Biomedical Engineering, University of Utah.
| |
Collapse
|
14
|
The Dosidicus gigas Collagen for Scaffold Preparation and Cell Cultivation: Mechanical and Physicochemical Properties, Morphology, Composition and Cell Viability. Polymers (Basel) 2023; 15:polym15051220. [PMID: 36904464 PMCID: PMC10006952 DOI: 10.3390/polym15051220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 01/19/2023] [Accepted: 01/30/2023] [Indexed: 03/04/2023] Open
Abstract
Directed formation of the structure of the culture of living cells is the most important task of tissue engineering. New materials for 3D scaffolds of living tissue are critical for the mass adoption of regenerative medicine protocols. In this manuscript, we demonstrate the results of the molecular structure study of collagen from Dosidicus gigas and reveal the possibility of obtaining a thin membrane material. The collagen membrane is characterized by high flexibility and plasticity as well as mechanical strength. The technology of obtaining collagen scaffolds, as well as the results of studies of its mechanical properties, surface morphology, protein composition, and the process of cell proliferation on its surface, are shown in the given manuscript. The investigation of living tissue culture grown on the surface of a collagen scaffold by X-ray tomography on a synchrotron source made it possible to remodel the structure of the extracellular matrix. It was found that the scaffolds obtained from squid collagen are characterized by a high degree of fibril ordering and high surface roughness and provide efficient directed growth of the cell culture. The resulting material provides the formation of the extracellular matrix and is characterized by a short time to living tissue sorption.
Collapse
|
15
|
Wang M, Sun S, Dong G, Long F, Butcher JT. Soft, strong, tough, and durable protein-based fiber hydrogels. Proc Natl Acad Sci U S A 2023; 120:e2213030120. [PMID: 36791112 PMCID: PMC9974439 DOI: 10.1073/pnas.2213030120] [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: 07/28/2022] [Accepted: 01/04/2023] [Indexed: 02/16/2023] Open
Abstract
Load-bearing soft tissues normally show J-shaped stress-strain behaviors with high compliance at low strains yet high strength at high strains. They have high water content but are still tough and durable. By contrast, naturally derived hydrogels are weak and brittle. Although hydrogels prepared from synthetic polymers can be strong and tough, they do not have the desired bioactivity for emerging biomedical applications. Here, we present a thermomechanical approach to replicate the combinational properties of soft tissues in protein-based photocrosslinkable hydrogels. As a demonstration, we create a gelatin methacryloyl fiber hydrogel with soft tissue-like mechanical properties, such as low Young's modulus (0.1 to 0.3 MPa), high strength (1.1 ± 0.2 MPa), high toughness (9,100 ± 2,200 J/m3), and high fatigue resistance (2,300 ± 500 J/m2). This hydrogel also resembles the biochemical and architectural properties of native extracellular matrix, which enables a fast formation of 3D interconnected cell meshwork inside hydrogels. The fiber architecture also regulates cellular mechanoresponse and supports cell remodeling inside hydrogels. The integration of tissue-like mechanical properties and bioactivity is highly desirable for the next-generation biomaterials and could advance emerging fields such as tissue engineering and regenerative medicine.
Collapse
Affiliation(s)
- Mingkun Wang
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY14853
| | - Shuofei Sun
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY14853
| | - Gening Dong
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY14853
| | - Feifei Long
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY14853
| | - Jonathan T. Butcher
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY14853
| |
Collapse
|
16
|
Silva Barreto I, Pierantoni M, Hammerman M, Törnquist E, Le Cann S, Diaz A, Engqvist J, Liebi M, Eliasson P, Isaksson H. Nanoscale characterization of collagen structural responses to in situ loading in rat Achilles tendons. Matrix Biol 2023; 115:32-47. [PMID: 36435426 DOI: 10.1016/j.matbio.2022.11.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 09/29/2022] [Accepted: 11/21/2022] [Indexed: 11/24/2022]
Abstract
The specific viscoelastic mechanical properties of Achilles tendons are highly dependent on the structural characteristics of collagen at and between all hierarchical levels. Research has been conducted on the deformation mechanisms of positional tendons and single fibrils, but knowledge about the coupling between the whole tendon and nanoscale deformation mechanisms of more commonly injured energy-storing tendons, such as Achilles tendons, remains sparse. By exploiting the highly periodic arrangement of tendons at the nanoscale, in situ loading of rat Achilles tendons during small-angle X-ray scattering acquisition was used to investigate the collagen structural response during load to rupture, cyclic loading and stress relaxation. The fibril strain was substantially lower than the applied tissue strain. The fibrils strained linearly in the elastic region of the tissue, but also exhibited viscoelastic properties, such as an increased stretchability and recovery during cyclic loading and fibril strain relaxation during tissue stress relaxation. We demonstrate that the changes in the width of the collagen reflections could be attributed to strain heterogeneity and not changes in size of the coherently diffracting domains. Fibril strain heterogeneity increased with applied loads and after the toe region, fibrils also became increasingly disordered. Additionally, a thorough evaluation of radiation damage was performed. In conclusion, this study clearly displays the simultaneous structural response and adaption of the collagen fibrils to the applied tissue loads and provide novel information about the transition of loads between length scales in the Achilles tendon.
Collapse
Affiliation(s)
| | - Maria Pierantoni
- Department of Biomedical Engineering, Lund University, Lund, Sweden
| | - Malin Hammerman
- Department of Biomedical Engineering, Lund University, Lund, Sweden; Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Elin Törnquist
- Department of Biomedical Engineering, Lund University, Lund, Sweden
| | - Sophie Le Cann
- CNRS, Univ Paris Est Creteil, Univ Gustave Eiffel, UMR 8208, MSME, Créteil F-94010, France
| | - Ana Diaz
- Paul Scherrer Institut, Villigen PSI, Switzerland
| | - Jonas Engqvist
- Division of Solid Mechanics, Lund University, Lund, Sweden
| | - Marianne Liebi
- Paul Scherrer Institut, Villigen PSI, Switzerland; Department of Physics, Chalmers University, Gothenburg, Sweden; Center of X-ray Analytics, Empa, Swiss Federal Laboratories for Materials Science and Technology, St.Gallen, Switzerland
| | - Pernilla Eliasson
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden; Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Hanna Isaksson
- Department of Biomedical Engineering, Lund University, Lund, Sweden.
| |
Collapse
|
17
|
Chawla D, Eriten M, Henak CR. Effect of osmolarity and displacement rate on cartilage microfracture clusters failure into two regimes. J Mech Behav Biomed Mater 2022; 136:105467. [PMID: 36198233 DOI: 10.1016/j.jmbbm.2022.105467] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 08/16/2022] [Accepted: 09/12/2022] [Indexed: 11/22/2022]
Abstract
Articular cartilage is a poroviscoelastic (PVE) material with remarkable resistance to fracture and fatigue failure. Cartilage failure mechanisms and material properties that govern failure are incompletely understood. Because cartilage is partially comprised of negatively charged glycosaminoglycans, altering solvent osmolarity can influence PVE relaxations. Therefore, this study aims to use osmolarity as a tool to provide additional data to interpret the role of PVE relaxations and identify cartilage failure regimes. Cartilage fracture was induced using a 100 μm radius spheroconical indenter at controlled displacement rates under three different osmolarity solvents. Secondarily, contact pressure (CP) and strain energy density (SED) were estimated to cluster data into two failure regimes with an expectation maximization algorithm. Critical displacement, critical load, critical time, and critical work to fracture increased with increasing osmolarity at a slow displacement rate whereas no significant effect was observed at a fast displacement rate. Clustering provided two distinct failure regimes, with regime (I) at lower normalized thickness (contact radius divided by sample thickness), and regime (II) at higher normalized thickness. Varied CP and SED in regime (I) suggest that failure in the regime is strain-governed. Constant CP and SED in regime (II) suggests that failure in the regime is dominantly governed by stress. These regimes can be interpreted as ductile versus brittle, or using a pressurized fragmentation interpretation. These findings demonstrated fundamental failure properties and postulate failure regimes for articular cartilage.
Collapse
Affiliation(s)
- Dipul Chawla
- Department of Mechanical Engineering, University of Wisconsin-Madison, 1513 University Ave., Madison, WI, 53706, USA
| | - Melih Eriten
- Department of Mechanical Engineering, University of Wisconsin-Madison, 1513 University Ave., Madison, WI, 53706, USA
| | - Corinne R Henak
- Department of Mechanical Engineering, University of Wisconsin-Madison, 1513 University Ave., Madison, WI, 53706, USA; Department of Biomedical Engineering, University of Wisconsin-Madison, 1550 University Ave., Madison, WI, 53706, USA; Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA.
| |
Collapse
|
18
|
Readioff R, Geraghty B, Kharaz YA, Elsheikh A, Comerford E. Proteoglycans play a role in the viscoelastic behaviour of the canine cranial cruciate ligament. Front Bioeng Biotechnol 2022; 10:984224. [DOI: 10.3389/fbioe.2022.984224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 10/31/2022] [Indexed: 11/17/2022] Open
Abstract
Proteoglycans (PGs) are minor extracellular matrix proteins, and their contributions to the mechanobiology of complex ligaments such as the cranial cruciate ligament (CCL) have not been determined to date. The CCLs are highly susceptible to injuries, and their extracellular matrix comprises higher PGs content than the other major knee ligaments. Hence these characteristics make CCLs an ideal specimen to use as a model in this study. This study addressed the hypothesis that PGs play a vital role in CCL mechanobiology by determining the biomechanical behaviour at low strain rates before and after altering PGs content. For the first time, this study qualitatively investigated the contribution of PGs to key viscoelastic characteristics, including strain rate dependency, hysteresis, creep and stress relaxation, in canine CCLs. Femur-CCL-tibia specimens (n = 6 pairs) were harvested from canine knee joints and categorised into a control group, where PGs were not depleted, and a treated group, where PGs were depleted. Specimens were preconditioned and cyclically loaded to 9.9 N at 0.1, 1 and 10%/min strain rates, followed by creep and stress relaxation tests. Low tensile loads were applied to focus on the toe-region of the stress-strain curves where the non-collagenous extracellular matrix components take significant effect. Biochemical assays were performed on the CCLs to determine PGs and water content. The PG content was ∼19% less in the treated group than in the control group. The qualitative study showed that the stress-strain curves in the treated group were strain rate dependent, similar to the control group. The CCLs in the treated group showed stiffer characteristics than the control group. Hysteresis, creep characteristics (creep strain, creep rate and creep compliance), and stress relaxation values were reduced in the treated group compared to the control group. This study suggests that altering PGs content changes the microstructural organisation of the CCLs, including water molecule contents which can lead to changes in CCL viscoelasticity. The change in mechanical properties of the CCLs may predispose to injury and lead to knee joint osteoarthritis. Future studies should focus on quantitatively identifying the effect of PG on the mechanics of intact knee ligaments across broader demography.
Collapse
|
19
|
Discovering design principles of collagen molecular stability using a genetic algorithm, deep learning, and experimental validation. Proc Natl Acad Sci U S A 2022; 119:e2209524119. [PMID: 36161946 DOI: 10.1073/pnas.2209524119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Collagen is the most abundant structural protein in humans, providing crucial mechanical properties, including high strength and toughness, in tissues. Collagen-based biomaterials are, therefore, used for tissue repair and regeneration. Utilizing collagen effectively during materials processing ex vivo and subsequent function in vivo requires stability over wide temperature ranges to avoid denaturation and loss of structure, measured as melting temperature (Tm). Although significant research has been conducted on understanding how collagen primary amino acid sequences correspond to Tm values, a robust framework to facilitate the design of collagen sequences with specific Tm remains a challenge. Here, we develop a general model using a genetic algorithm within a deep learning framework to design collagen sequences with specific Tm values. We report 1,000 de novo collagen sequences, and we show that we can efficiently use this model to generate collagen sequences and verify their Tm values using both experimental and computational methods. We find that the model accurately predicts Tm values within a few degrees centigrade. Further, using this model, we conduct a high-throughput study to identify the most frequently occurring collagen triplets that can be directly incorporated into collagen. We further discovered that the number of hydrogen bonds within collagen calculated with molecular dynamics (MD) is directly correlated to the experimental measurement of triple-helical quality. Ultimately, we see this work as a critical step to helping researchers develop collagen sequences with specific Tm values for intended materials manufacturing methods and biomedical applications, realizing a mechanistic materials by design paradigm.
Collapse
|
20
|
Khare E, Gonzalez-Obeso C, Kaplan DL, Buehler MJ. CollagenTransformer: End-to-End Transformer Model to Predict Thermal Stability of Collagen Triple Helices Using an NLP Approach. ACS Biomater Sci Eng 2022; 8:4301-4310. [PMID: 36149671 DOI: 10.1021/acsbiomaterials.2c00737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Collagen is one of the most important structural proteins in biology, and its structural hierarchy plays a crucial role in many mechanically important biomaterials. Here, we demonstrate how transformer models can be used to predict, directly from the primary amino acid sequence, the thermal stability of collagen triple helices, measured via the melting temperature Tm. We report two distinct transformer architectures to compare performance. First, we train a small transformer model from scratch, using our collagen data set featuring only 633 sequence-to-Tm pairings. Second, we use a large pretrained transformer model, ProtBERT, and fine-tune it for a particular downstream task by utilizing sequence-to-Tm pairings, using a deep convolutional network to translate natural language processing BERT embeddings into required features. Both the small transformer model and the fine-tuned ProtBERT model have similar R2 values of test data (R2 = 0.84 vs 0.79, respectively), but the ProtBERT is a much larger pretrained model that may not always be applicable for other biological or biomaterials questions. Specifically, we show that the small transformer model requires only 0.026% of the number of parameters compared to the much larger model but reaches almost the same accuracy for the test set. We compare the performance of both models against 71 newly published sequences for which Tm has been obtained as a validation set and find reasonable agreement, with ProtBERT outperforming the small transformer model. The results presented here are, to our best knowledge, the first demonstration of the use of transformer models for relatively small data sets and for the prediction of specific biophysical properties of interest. We anticipate that the work presented here serves as a starting point for transformer models to be applied to other biophysical problems.
Collapse
Affiliation(s)
- Eesha Khare
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, United States.,Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, United States
| | | | - David L Kaplan
- Tufts University, Medford, Massachusetts 02155, United States
| | - Markus J Buehler
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, United States.,Center for Computational Science and Engineering, Schwarzman College of Computing, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, United States
| |
Collapse
|
21
|
Johari N, Khodaei A, Samadikuchaksaraei A, Reis RL, Kundu SC, Moroni L. Ancient fibrous biomaterials from silkworm protein fibroin and spider silk blends: Biomechanical patterns. Acta Biomater 2022; 153:38-67. [PMID: 36126911 DOI: 10.1016/j.actbio.2022.09.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 08/26/2022] [Accepted: 09/13/2022] [Indexed: 11/15/2022]
Abstract
Silkworm silk protein fibroin and spider silk spidroin are known biocompatible and natural biodegradable polymers in biomedical applications. The presence of β-sheets in silk fibroin and spider spidroin conformation improves their mechanical properties. The strength and toughness of pure recombinant silkworm fibroin and spidroin are relatively low due to reduced molecular weight. Hence, blending is the foremost approach of recent studies to optimize silk fibroin and spidroin's mechanical properties. As summarised in the present review, numerous research investigations evaluate the blending of natural and synthetic polymers. The effects of blending silk fibroin and spidroin with natural and synthetic polymers on the mechanical properties are discussed in this review article. Indeed, combining natural and synthetic polymers with silk fibroin and spidroin changes their conformation and structure, fine-tuning the blends' mechanical properties. STATEMENT OF SIGNIFICANCE: Silkworm and spider silk proteins (silk fibroin and spidroin) are biocompatible and biodegradable natural polymers having different types of biomedical applications. Their mechanical and biological properties may be tuned through various strategies such as blending, conjugating and cross-linking. Blending is the most common method to modify fibroin and spidroin properties on demand, this review article aims to categorize and evaluate the effects of blending fibroin and spidroin with different natural and synthetic polymers. Increased polarity and hydrophilicity end to hydrogen bonding triggered conformational change in fibroin and spidroin blends. The effect of polarity and hydrophilicity of the blending compound is discussed and categorized to a combinatorial, synergistic and indirect impacts. This outlook guides us to choose the blending compounds mindfully as this mixing affects the biochemical and biophysical characteristics of the biomaterials.
Collapse
Affiliation(s)
- Narges Johari
- Materials Engineering group, Golpayegan College of Engineering, Isfahan University of Technology, Golpayegan, Iran.
| | - Azin Khodaei
- Department of Orthopedics, University Medical Center Utrecht, Utrecht, The Netherlands.
| | - Ali Samadikuchaksaraei
- Department of Medical Biotechnology, Faculty of Allied Medicine, Iran University of Medical Science, Tehran, Iran.
| | - Rui L Reis
- 3B's Research Group, I3Bs - Research Institute on Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, Parque de Ciência e Tecnologia, 4805-017 Barco, Guimarães, Portugal.
| | - Subhas C Kundu
- 3B's Research Group, I3Bs - Research Institute on Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, Parque de Ciência e Tecnologia, 4805-017 Barco, Guimarães, Portugal.
| | - Lorenzo Moroni
- Maastricht University, MERLN Institute for Technology Inspired Regenerative Medicine, Complex Tissue Regeneration Department, Maastricht, The Netherlands.
| |
Collapse
|
22
|
Haverkamp RG, Sizeland KH, Wells HC, Kamma-Lorger C. Collagen dehydration. Int J Biol Macromol 2022; 216:140-147. [DOI: 10.1016/j.ijbiomac.2022.06.180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 06/27/2022] [Indexed: 11/05/2022]
|
23
|
Carvalho EM, Kumar S. Lose the stress: Viscoelastic materials for cell engineering. Acta Biomater 2022; 163:146-157. [PMID: 35405329 DOI: 10.1016/j.actbio.2022.03.058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 03/21/2022] [Accepted: 03/31/2022] [Indexed: 11/30/2022]
Abstract
Biomaterials are widely used to study and control a variety of cell behaviors, including stem cell differentiation, organogenesis, and tumor invasion. While considerable attention has historically been paid to biomaterial elastic (storage) properties, it has recently become clear that viscous (loss) properties can also powerfully influence cell behavior. Here we review advances in viscoelastic materials for cell engineering. We begin by discussing collagen, an abundant naturally occurring biomaterial that derives its viscoelastic properties from its fibrillar architecture, which enables dissipation of applied stresses. We then turn to two other naturally occurring biomaterials that are more frequently modified for engineering applications, alginate and hyaluronic acid, whose viscoelastic properties may be tuned by modulating network composition and crosslinking. We also discuss the potential of exploiting engineered fibrous materials, particularly electrospun fiber-based materials, to control viscoelastic properties. Finally, we review mechanisms through which cells process viscous and viscoelastic cues as they move along and within these materials. The ability of viscoelastic materials to relax cell-imposed stresses can dramatically alter migration on two-dimensional surfaces and confinement-imposed barriers to engraftment and infiltration in three-dimensional scaffolds. STATEMENT OF SIGNIFICANCE: Most tissues and many biomaterials exhibit some viscous character, a property that is increasingly understood to influence cell behavior in profound ways. This review discusses the origin and significance of viscoelastic properties of common biomaterials, as well as how these cues are processed by cells to influence migration. A deeper understanding of the mechanisms of viscoelastic behavior in biomaterials and how cells interpret these inputs should aid the design and selection of biomaterials for specific applications.
Collapse
Affiliation(s)
- Emily M Carvalho
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720, USA
| | - Sanjay Kumar
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720, USA; San Francisco Graduate, Program in Bioengineering, University of California, Berkeley-University of California, Berkeley, CA 94720, USA; Department of Bioengineering, University of California, Berkeley, CA 94720, USA; Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94158, USA.
| |
Collapse
|
24
|
Yang F, Das D, Karunakaran K, Genin GM, Thomopoulos S, Chasiotis I. Nonlinear time-dependent mechanical behavior of mammalian collagen fibrils. Acta Biomater 2022; 163:63-77. [PMID: 35259515 PMCID: PMC9441475 DOI: 10.1016/j.actbio.2022.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [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.
Collapse
|
25
|
Fewster KM, Barrett JM, Callaghan JP. Characterizing the Mechanical and Viscoelastic Response of the Porcine Facet Joint Capsule Ligament in Response to a Simulated Impact. J Biomech Eng 2022; 144:1139235. [PMID: 35244145 DOI: 10.1115/1.4054022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Indexed: 11/08/2022]
Abstract
The facet capsule ligament (FCL) is a structure in the lumbar spine that constrains motions of the vertebrae. Subfailure loads can produce micro-damage resulting in increased laxity, decreased stiffness, and altered viscoelastic responses. Therefore, the purpose of this investigation was to determine the mechanical and viscoelastic properties of the FCL under various magnitudes of strain from control samples and samples that had been through an impact protocol. Two hundred FCL tissue samples were tested (20 Control & 180 Impacted). Impacted FCL tissue samples were obtained from functional spinal units that had been exposed to one of nine sub-failure impact conditions. All specimens underwent to following loading protocol: preconditioning with 5 cycles of 5% strain, followed by a 30 second rest period, 5 cycles of 10% strain and 1 cycle of 10% strain with a hold duration at 10% strain for 240 seconds (4 minutes). The same protocol followed for 30% and 50% strain. Measures of stiffness, hysteresis and force-relaxation were computed. No significant differences in stiffness were observed for impacted specimens in comparison to control. Impacted specimens from the 8g Flexed and 11g Flexed and Neutral conditions exhibited greater hysteresis during the cyclic-30% and cyclic-50% portion of the protocol in comparison to controls. In addition, specimens from the 8g and 11g Flexed conditions resulted in greater stress decay for the 50%-hold conditions. Results from this study demonstrate viscoelastic changes in FCL samples exposed to moderate and highspeed single impacts in a flexed posture.
Collapse
Affiliation(s)
- Kayla M Fewster
- Department of Kinesiology, University of Waterloo, Waterloo, ON
| | - Jeff M Barrett
- Department of Kinesiology, University of Waterloo, Waterloo, ON
| | | |
Collapse
|
26
|
Rausch M, Meador WD, Toaquiza-Tubon J, Moreno-Flores O, Tepole AB. Biaxial mechanics of thermally denaturing skin - Part 2: Modeling. Acta Biomater 2022; 140:421-433. [PMID: 34856415 DOI: 10.1016/j.actbio.2021.11.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 11/02/2021] [Accepted: 11/22/2021] [Indexed: 11/01/2022]
Abstract
Understanding the response of skin to superphysiological temperatures is critical to the diagnosis and prognosis of thermal injuries, and to the development of temperature-based medical therapeutics. Unfortunately, this understanding has been hindered by our incomplete knowledge about the nonlinear coupling between skin temperature and its mechanics. In Part I of this study we experimentally demonstrated a complex interdependence of time, temperature, direction, and load in skin's response to superphysiological temperatures. In Part II of our study, we test two different models of skin's thermo-mechanics to explain our observations. In both models we assume that skin's response to superphysiological temperatures is governed by the denaturation of its highly collageneous microstructure. Thus, we capture skin's native mechanics via a microstructurally-motivated strain energy function which includes probability distributions for collagen fiber orientation and waviness. In the first model, we capture skin's response to superphysiological temperatures as a transition between two states that link the kinetics of collagen fiber denaturation to fiber coiling and to the transformation of each fiber's constitutive behavior from purely elastic to viscoelastic. In the second model, we capture skin's response to superphysiological temperatures instead via three states in which a sequence of two reactions link the kinetics of collagen fiber denaturation to fiber coiling, followed by a state of fiber damage. Given the success of both models in qualitatively and quantitatively capturing our observations, we expect that our work will provide guidance for future experiments that could probe each model's assumptions toward a better understanding of skin's coupled thermo-mechanics and that our work will be used to guide the engineering design of heat treatment therapies. STATEMENT OF SIGNIFICANCE: Quantifying and modeling skin thermo-mechanics is critical to our understanding of skin physiology, pathophysiology, as well as heat-based treatments. This work addresses a lack of theoretical and computational models of the coupled thermo-mechanics of skin. Our model accounts for skin microstructure through modeling the probability of fiber orientation and fiber stress-free states. Denaturing induces changes in the stress-free configuration of collagen, as well as changes in fiber stiffness and viscoelastic properties. We propose two competing models that fit all of our experimental observations. These models will enable future developments of thermal-therapeutics, prevention and management of skin thermal injuries, and set a foundation for improved mechanistic models of skin thermo-mechanics.
Collapse
|
27
|
Zhang Y, Hollis D, Ross R, Snow T, Terrill NJ, Lu Y, Wang W, Connelly J, Tozzi G, Gupta HS. Investigating the Fibrillar Ultrastructure and Mechanics in Keloid Scars Using In Situ Synchrotron X-ray Nanomechanical Imaging. MATERIALS 2022; 15:ma15051836. [PMID: 35269067 PMCID: PMC8911729 DOI: 10.3390/ma15051836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 10/24/2021] [Accepted: 01/21/2022] [Indexed: 12/10/2022]
Abstract
Fibrotic scarring is prevalent in a range of collagenous tissue disorders. Understanding the role of matrix biophysics in contributing to fibrotic progression is important to develop therapies, as well as to elucidate biological mechanisms. Here, we demonstrate how microfocus small-angle X-ray scattering (SAXS), with in situ mechanics and correlative imaging, can provide quantitative and position-resolved information on the fibrotic matrix nanostructure and its mechanical properties. We use as an example the case of keloid scarring in skin. SAXS mapping reveals heterogeneous gradients in collagen fibrillar concentration, fibril pre-strain (variations in D-period) and a new interfibrillar component likely linked to proteoglycans, indicating evidence of a complex 3D structure at the nanoscale. Furthermore, we demonstrate a proof-of-principle for a diffraction-contrast correlative imaging technique, incorporating, for the first time, DIC and SAXS, and providing an initial estimate for measuring spatially resolved fibrillar-level strain and reorientation in such heterogeneous tissues. By application of the method, we quantify (at the microscale) fibrillar reorientations, increases in fibrillar D-period variance, and increases in mean D-period under macroscopic tissue strains of ~20%. Our results open the opportunity of using synchrotron X-ray nanomechanical imaging as a quantitative tool to probe structure–function relations in keloid and other fibrotic disorders in situ.
Collapse
Affiliation(s)
- Yuezhou Zhang
- Institute of Bioengineering and School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK; (Y.Z.); (W.W.)
| | - Dave Hollis
- LaVision UK, 2 Minton Place, Victoria Road, Bicester OX26 6QB, UK;
| | - Rosie Ross
- Centre for Cell Biology and Cutaneous Research, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK; (R.R.); (J.C.)
| | - Tim Snow
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK; (T.S.); (N.J.T.)
| | - Nick J. Terrill
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK; (T.S.); (N.J.T.)
| | - Yongjie Lu
- Centre for Biomarkers and Biotherapeutics, Barts Cancer Institute, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 5PZ, UK;
| | - Wen Wang
- Institute of Bioengineering and School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK; (Y.Z.); (W.W.)
| | - John Connelly
- Centre for Cell Biology and Cutaneous Research, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK; (R.R.); (J.C.)
| | - Gianluca Tozzi
- School of Engineering, London South Bank University, London SE1 0AA, UK;
| | - Himadri S. Gupta
- Institute of Bioengineering and School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK; (Y.Z.); (W.W.)
- Correspondence:
| |
Collapse
|
28
|
Yang F, Das D, Chasiotis I. Microscale Creep and Stress Relaxation Experiments with Individual Collagen Fibrils. OPTICS AND LASERS IN ENGINEERING 2022; 150:106869. [PMID: 35027783 PMCID: PMC8752082 DOI: 10.1016/j.optlaseng.2021.106869] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Nanoscale macromolecular biological structures exhibit time-dependent behavior, yet a quantitative understanding of their time-dependent mechanical behavior remains elusive, largely due to experimental challenges in attaining sufficient spatial and temporal resolution and control of stress or strain in conditions that guarantee their molecular integrity. To address this gap, an experimental methodology was developed to conduct creep and stress relaxation experiments with individual mammalian collagen fibrils. An image-based edge detection method implemented with high magnification optical microscopy and combined with closed-loop proportional-integral-derivative (PID) control was implemented and calibrated to apply constant force or stretch ratio values to individual collagen fibrils via a Microelectromechanical Systems (MEMS) device. This experimental methodology allowed for real-time control of uniaxial tensile stress or strain with 27 nm displacement resolution. The overall experimental system was tuned to apply step inputs with rise times below 0.5 s, less than 2.5% overshoot, and steady-state error less than 0.5%. Three individual collagen fibrils with diameters 101-121 nm were subjected to creep and stress relaxation tests in the range 4-20% engineering strain, under partially hydrated conditions. The collagen fibrils demonstrated non-linear viscoelastic behavior that was described well by the adaptive quasi-linear viscoelastic model. The results of this study demonstrate for the first time that mammalian collagen fibrils, the building blocks of connective tissues, exhibit nonlinear viscoelastic behavior in their partially hydrated state.
Collapse
Affiliation(s)
- Fan Yang
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Debashish Das
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Ioannis Chasiotis
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| |
Collapse
|
29
|
Tran DT, Guang Zhan Y, Tsai L. Dynamic tensile properties of porcine knee ligament. Biomed Mater Eng 2022; 33:293-302. [PMID: 35213341 DOI: 10.3233/bme-211318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND The knee plays an essential role in movement. There are four major ligaments in the knee which all have crucial functionalities for human activities. The anterior cruciate ligament (ACL) is the most commonly injured ligament in the knee, especially in athletes. OBJECTIVE The aim of this study was to investigate the dynamic tensile response of the porcine ACL at strain rates from 800 to 1500 s-1 for simulations of acute injury from sudden impact or collision. METHODS Split Hopkinson Tension Bar (SHTB) was utilized to create a dynamic tensile wave on the ACL. Stress-strain curves of strain rates between 800 s-1 to 1500 s-1 were recorded. RESULTS The results demonstrated that the elastic modulus of the porcine ACL at higher strain rates was six to eight times higher than that of porcine and human specimens at quasi-static strain rate. However, the failure stress was quite similar while the strain was much smaller than that at the lower strain rate. CONCLUSIONS ACL is highly strain rate sensitive and easier to break with lower failure strain when the strain rates increased to more than 1000 s-1. The stress-strain curves indicated that the sketching crimps at the slack region did not happen but switched to the sliding process of collagen fibers and was accompanied by some ruptures, which can develop into tears when strain and stress were large enough. On the other hand, the viscoelastic properties of the ligament, depending on the proteoglycan matrix and the cross-link, showed a limited value in the studied strain rate range.
Collapse
Affiliation(s)
- Dat Trong Tran
- Department of Mechanical Engineering, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan.,School of Transportation Engineering, Hanoi University of Science and Technology, Hanoi, Vietnam
| | - Yao Guang Zhan
- Department of Mechanical Engineering, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan
| | - Liren Tsai
- Department of Mechanical Engineering, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan
| |
Collapse
|
30
|
A mathematical model for viscoelastic properties of biological soft tissue. Theory Biosci 2022; 141:13-25. [PMID: 35112309 DOI: 10.1007/s12064-021-00361-7] [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: 10/01/2020] [Accepted: 12/15/2021] [Indexed: 10/19/2022]
Abstract
A quaternary viscoelastic structure model with two characteristic times is presented to describe the viscoelastic properties of parallel-fibered collagen tissue. The comparison results of model prediction and experimental data of rabbit medial collateral ligaments show that the model could accurately describe viscoelastic behavior such as stress-relaxation, strain-strengthening and creep of bio-soft-tissue within a small scope of errors. To study the biomechanical mechanism of viscoelasticity that biological soft tissue shows, the influence of model parameters on viscoelastic behavior of bio-soft-tissue is analyzed and researched, which indicated that the major influential elements of stress-relaxation in bio-soft-tissue are elastic modulus, relaxation time and strain rate of proteoglycan-rich matrix. The influence of elastic modulus of collagen fibers on stress-relaxation is not significant. However, the nonlinearity of stress-strain curve and viscoelastic behavior of bio-soft-tissue mostly depends on recruitment and reorientation of collagen fibers under external loading.
Collapse
|
31
|
Effects of Extrusion and Irradiation on the Mechanical Properties of a Water–Collagen Solution. Polymers (Basel) 2022; 14:polym14030578. [PMID: 35160567 PMCID: PMC8840162 DOI: 10.3390/polym14030578] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 01/21/2022] [Accepted: 01/28/2022] [Indexed: 02/04/2023] Open
Abstract
This article describes 1D extension tests on bovine collagen samples (8% collagen in water). At such a high collagen concentration, the mechanical properties of semi-solid samples can be approximated by hyperelastic models (two-parametric HGO and Misof models were used), or simply by Hooke’s law and the modulus of elasticity E. The experiments confirm a significant increase in the E-modulus of the samples irradiated with high-energy electrons. The modulus E~9 kPa of non-irradiated samples increases monotonically up to E~250 kPa for samples absorbing an e-beam dose of ~3300 Gy. This amplification is attributed to the formation of cross-links by irradiation. However, E-modulus can be increased not only by irradiation but also by exposure to a high strain rate. For example, soft isotropic collagen extruded through a 200 mm long capillary increases the modulus of elasticity from 9 kPa to 30 kPa, and the increase is almost isotropic. This stiffening occurs when the corrugated collagen fibers are straightened and are aligned in the flow direction. It seems that the permanent structural changes caused by extrusion mitigate the effects of the ex post applied irradiation. Irradiation of extruded samples by 3300 Gy increases the modulus of E-elasticity only three times (from 30 kPa to approximately 90 kPa). Extruded and ex post irradiated samples show slight anisotropy (the stiffness in the longitudinal direction is on an average greater than the transverse stiffness).
Collapse
|
32
|
Hwang JW, Chawla D, Han G, Eriten M, Henak CR. Effects of solvent osmolarity and viscosity on cartilage energy dissipation under high-frequency loading. J Mech Behav Biomed Mater 2021; 126:105014. [PMID: 34871958 DOI: 10.1016/j.jmbbm.2021.105014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/29/2021] [Accepted: 11/27/2021] [Indexed: 01/16/2023]
Abstract
Articular cartilage is a spatially heterogeneous, dissipative biological hydrogel with a high fluid volume fraction. Although energy dissipation is important in the context of delaying cartilage damage, the dynamic behavior of articular cartilage equilibrated in media of varied osmolarity and viscosity is not widely understood. This study investigated the mechanical behaviors of cartilage when equilibrated to media of varying osmolarity and viscosity. Dynamic moduli and phase shift were measured at both low (1 Hz) and high (75-300 Hz) frequency, with cartilage samples compressed to varied offset strain levels. Increasing solution osmolarity and viscosity both independently resulted in larger energy dissipation and decreased dynamic modulus of cartilage at both low and high frequency. Mechanical property alterations induced by varying osmolarity are likely due to the change in permeability and fluid volume fraction within the tissue. The effects of solution viscosity are likely due to frictional interactions at the solid-fluid interface, affecting energy dissipation. These findings highlight the significance of interstitial fluid on the energy dissipation capabilities of the tissue, which can influence the onset of cartilage damage.
Collapse
Affiliation(s)
- Jin Wook Hwang
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Dipul Chawla
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Guebum Han
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Melih Eriten
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Corinne R Henak
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA; Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA; Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, Madison, WI, USA.
| |
Collapse
|
33
|
ColGen: An end-to-end deep learning model to predict thermal stability of de novo collagen sequences. J Mech Behav Biomed Mater 2021; 125:104921. [PMID: 34758444 DOI: 10.1016/j.jmbbm.2021.104921] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 10/21/2021] [Indexed: 11/22/2022]
Abstract
Collagen is the most abundant structural protein in humans, with dozens of sequence variants accounting for over 30% of the protein in an animal body. The fibrillar and hierarchical arrangements of collagen are critical in providing mechanical properties with high strength and toughness. Due to this ubiquitous role in human tissues, collagen-based biomaterials are commonly used for tissue repairs and regeneration, requiring chemical and thermal stability over a range of temperatures during materials preparation ex vivo and subsequent utility in vivo. Collagen unfolds from a triple helix to a random coil structure during a temperature interval in which the midpoint or Tm is used as a measure to evaluate the thermal stability of the molecules. However, finding a robust framework to facilitate the design of a specific collagen sequence to yield a specific Tm remains a challenge, including using conventional molecular dynamics modeling. Here we propose a de novo framework to provide a model that outputs the Tm values of input collagen sequences by incorporating deep learning trained on a large data set of collagen sequences and corresponding Tm values. By using this framework, we are able to quickly evaluate how mutations and order in the primary sequence affect the stability of collagen triple helices. Specifically, we confirm that mutations to glycines, mutations in the middle of a sequence, and short sequence lengths cause the greatest drop in Tm values.
Collapse
|
34
|
Al Makhzoomi AK, Kirk TB, Dye DE, Allison GT. Contribution of glycosaminoglycans to the structural and mechanical properties of tendons - A multiscale study. J Biomech 2021; 128:110796. [PMID: 34649066 DOI: 10.1016/j.jbiomech.2021.110796] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 09/17/2021] [Accepted: 10/03/2021] [Indexed: 11/18/2022]
Abstract
Tendinopathy of the Achilles tendon contributes to a large range of disorders, including mechanical damage and degenerative diseases. Glycosaminoglycans (GAGs), are thought to play a role in the mechanical strength of tendons by forming cross-links between collagen molecules and allowing the transmission of forces between fibrils. This study assessed the response of GAG-depleted tendons to damage induced by fatigue loading, investigating the mechanical damage (stiffness, hysteresis and maximum load), macrostructural changes (tenocyte morphology, fiber anisotropy and waviness) assessed by confocal imaging and nanostructural changes (fibril D-periodicity length) within the same non-viable intact tendons. Changes in fiber waviness and tenocyte shape are strongly correlated to mechanical and nano-structural (D-periodicity elongation) properties in both Control and GAG-depleted tendons. This study supports firstly, the vital role GAGs play as mechanical connectors facilitating the load transfer between the fibrils and their hydrophilic role in facilitating fibril sliding. Secondly, that observed changes in tenocyte shape and fiber waviness correlate with tendon stiffness and other mechanical profiles.
Collapse
Affiliation(s)
- Anas K Al Makhzoomi
- School of Allied Health, Faculty of Health Science, Curtin University, Perth, Western Australia, Australia.
| | - Thomas B Kirk
- School of Science, Engineering and Technology, RMIT University Vietnam, Ho Chi Minh City, Vietnam
| | - Danielle E Dye
- Curtin Medical School, Faculty of Health Sciences, Curtin University, Perth, Western Australia, Australia
| | - Garry T Allison
- Research Office, Curtin University, Perth, Western Australia, Australia
| |
Collapse
|
35
|
Nordsletten D, Capilnasiu A, Zhang W, Wittgenstein A, Hadjicharalambous M, Sommer G, Sinkus R, Holzapfel GA. A viscoelastic model for human myocardium. Acta Biomater 2021; 135:441-457. [PMID: 34487858 DOI: 10.1016/j.actbio.2021.08.036] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 08/22/2021] [Accepted: 08/24/2021] [Indexed: 01/06/2023]
Abstract
Understanding the biomechanics of the heart in health and disease plays an important role in the diagnosis and treatment of heart failure. The use of computational biomechanical models for therapy assessment is paving the way for personalized treatment, and relies on accurate constitutive equations mapping strain to stress. Current state-of-the art constitutive equations account for the nonlinear anisotropic stress-strain response of cardiac muscle using hyperelasticity theory. While providing a solid foundation for understanding the biomechanics of heart tissue, most current laws neglect viscoelastic phenomena observed experimentally. Utilizing experimental data from human myocardium and knowledge of the hierarchical structure of heart muscle, we present a fractional nonlinear anisotropic viscoelastic constitutive model. The model is shown to replicate biaxial stretch, triaxial cyclic shear and triaxial stress relaxation experiments (mean error ∼7.68%), showing improvements compared to its hyperelastic (mean error ∼24%) counterparts. Model sensitivity, fidelity and parameter uniqueness are demonstrated. The model is also compared to rate-dependent biaxial stretch as well as different modes of biaxial stretch, illustrating extensibility of the model to a range of loading phenomena. STATEMENT OF SIGNIFICANCE: The viscoelastic response of human heart tissues has yet to be integrated into common constitutive models describing cardiac mechanics. In this work, a fractional viscoelastic modeling approach is introduced based on the hierarchical structure of heart tissue. From these foundations, the current state-of-the-art biomechanical models of the heart muscle are transformed using fractional viscoelasticity, replicating passive muscle function across multiple experimental tests. Comparisons are drawn with current models to highlight the improvements of this approach and predictive responses show strong qualitative agreement with experimental data. The proposed model presents the first constitutive model aimed at capturing viscoelastic nonlinear response across multiple testing regimes, providing a platform for better understanding the biomechanics of myocardial tissue in health and disease.
Collapse
Affiliation(s)
- David Nordsletten
- Division of Biomedical Engineering and Imaging Sciences, Department of Biomedical Engineering, King's College London, UK; Departments of Biomedical Engineering and Cardiac Surgery, University of Michigan, North Campus Research Center, Building 20, 2800 Plymouth Rd, Ann Arbor 48109, MI, USA.
| | - Adela Capilnasiu
- Division of Biomedical Engineering and Imaging Sciences, Department of Biomedical Engineering, King's College London, UK
| | - Will Zhang
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, USA
| | - Anna Wittgenstein
- Division of Biomedical Engineering and Imaging Sciences, Department of Biomedical Engineering, King's College London, UK
| | | | - Gerhard Sommer
- Institute of Biomechanics, Graz University of Technology, Austria
| | - Ralph Sinkus
- Division of Biomedical Engineering and Imaging Sciences, Department of Biomedical Engineering, King's College London, UK; Inserm U1148, LVTS, University Paris Diderot, University Paris 13, Paris, France
| | - Gerhard A Holzapfel
- Institute of Biomechanics, Graz University of Technology, Austria; Department of Structural Engineering, Norwegian University of Science and Technology, Trondheim, Norway
| |
Collapse
|
36
|
Morin C, Hellmich C, Nejim Z, Avril S. Fiber Rearrangement and Matrix Compression in Soft Tissues: Multiscale Hypoelasticity and Application to Tendon. Front Bioeng Biotechnol 2021; 9:725047. [PMID: 34712652 PMCID: PMC8546211 DOI: 10.3389/fbioe.2021.725047] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 09/06/2021] [Indexed: 11/13/2022] Open
Abstract
It is widely accepted that the nonlinear macroscopic mechanical behavior of soft tissue is governed by fiber straightening and re-orientation. Here, we provide a quantitative assessment of this phenomenon, by means of a continuum micromechanics approach. Given the negligibly small bending stiffness of crimped fibers, the latter are represented through a number of hypoelastic straight fiber phases with different orientations, being embedded into a hypoelastic matrix phase. The corresponding representative volume element (RVE) hosting these phases is subjected to “macroscopic” strain rates, which are downscaled to fiber and matrix strain rates on the one hand, and to fiber spins on the other hand. This gives quantitative access to the fiber decrimping (or straightening) phenomenon under non-affine conditions, i.e. in the case where the fiber orientations cannot be simply linked to the macroscopic strain state. In the case of tendinous tissue, such an RVE relates to the fascicle material with 50 μm characteristic length, made up of crimped collagen bundles and a gel-type matrix in-between. The fascicles themselves act as parallel fibers in a similar matrix at the scale of a tissue-related RVE with 500 μm characteristic length. As evidenced by a sensitivity analysis and confirmed by various mechanical tests, it is the initial crimping angle which drives both the degree of straightening and the shape of the macroscopic stress-strain curve, while the final linear portion of this curve depends almost exclusively on the collagen bundle elasticity. Our model also reveals the mechanical cooperation of the tissue’s key microstructural components: while the fibers carry tensile forces, the matrices undergo hydrostatic pressure.
Collapse
Affiliation(s)
- Claire Morin
- Mines Saint-Etienne, Univ. Lyon, Univ. Jean Monnet, INSERM, U1059 Sainbiose, Centre CIS, Saint-Etienne, France
| | - Christian Hellmich
- Institute for Mechanics of Materials and Structures, TU Wien - Vienna University of Technology, Vienna, Austria
| | - Zeineb Nejim
- Mines Saint-Etienne, Univ. Lyon, Univ. Jean Monnet, INSERM, U1059 Sainbiose, Centre CIS, Saint-Etienne, France
| | - Stéphane Avril
- Mines Saint-Etienne, Univ. Lyon, Univ. Jean Monnet, INSERM, U1059 Sainbiose, Centre CIS, Saint-Etienne, France.,Institute for Mechanics of Materials and Structures, TU Wien - Vienna University of Technology, Vienna, Austria
| |
Collapse
|
37
|
Mlyniec A, Dabrowska S, Heljak M, Weglarz WP, Wojcik K, Ekiert-Radecka M, Obuchowicz R, Swieszkowski W. The dispersion of viscoelastic properties of fascicle bundles within the tendon results from the presence of interfascicular matrix and flow of body fluids. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2021; 130:112435. [PMID: 34702520 DOI: 10.1016/j.msec.2021.112435] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Revised: 09/06/2021] [Accepted: 09/09/2021] [Indexed: 01/12/2023]
Abstract
In this work, we investigate differences in the mechanical and structural properties of tendon fascicle bundles dissected from different areas of bovine tendons. The properties of tendon fascicle bundles were investigated by means of uniaxial tests with relaxation periods and hysteresis, dynamic mechanical analysis (DMA), as well as magnetic resonance imaging (MRI). Uniaxial tests with relaxation periods revealed greater elastic modulus, hysteresis, as well as stress drop during the relaxation of samples dissected from the posterior side of the tendon. However, the normalized stress relaxation curves did not show a statistically significant difference in the stress drop between specimens cut from different zones or between different strain levels. Using dynamic mechanical analysis, we found that fascicle bundles dissected from the anterior side of the tendon had lower storage and loss moduli, which could result from altered fluid flow within the interfascicular matrix (IFM). The lower water content, diffusivity, and higher fractional anisotropy of the posterior part of the tendon, as observed using MRI, indicates a different structure of the IFM, which controls the flow of fluids within the tendon. Our results show that the viscoelastic response to dynamic loading is correlated with fluid flow within the IFM, which was confirmed during analysis of the MRI results. In contrast to this, the long-term relaxation of tendon fascicle bundles is controlled by viscoplasticity of the IFM and depends on the spatial distribution of the matrix within the tendon. Comparison of results from tensile tests, DMA, and MRI gives new insight into tendon mechanics and the role of the IFM. These findings may be useful in improving the diagnosis of tendon injury and effectiveness of medical treatments for tendinopathies.
Collapse
Affiliation(s)
- Andrzej Mlyniec
- AGH University of Science and Technology, Faculty of Mechanical Engineering and Robotics, Krakow, Poland.
| | - Sylwia Dabrowska
- AGH University of Science and Technology, Faculty of Mechanical Engineering and Robotics, Krakow, Poland
| | - Marcin Heljak
- Warsaw University of Technology, Faculty of Materials Science and Engineering, Warsaw, Poland
| | | | - Kaja Wojcik
- AGH University of Science and Technology, Faculty of Mechanical Engineering and Robotics, Krakow, Poland
| | - Martyna Ekiert-Radecka
- AGH University of Science and Technology, Faculty of Mechanical Engineering and Robotics, Krakow, Poland
| | - Rafal Obuchowicz
- Jagiellonian University Collegium Medicum, Department of Radiology, Krakow, Poland
| | - Wojciech Swieszkowski
- Warsaw University of Technology, Faculty of Materials Science and Engineering, Warsaw, Poland
| |
Collapse
|
38
|
Al Makhzoomi AK, Kirk TB, Allison GT. An AFM study of the nanostructural response of New Zealand white rabbit Achilles tendons to cyclic loading. Microsc Res Tech 2021; 85:728-737. [PMID: 34632676 DOI: 10.1002/jemt.23944] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/14/2021] [Accepted: 09/09/2021] [Indexed: 01/21/2023]
Abstract
The nanostructural response of New Zealand white rabbit Achilles tendons to a fatigue damage model was assessed quantitatively and qualitatively using the endpoint of dose assessments of each tendon from our previous study. The change in mechanical properties was assessed concurrently with nanostructural change in the same non-viable intact tendon. Atomic force microscopy was used to study the elongation of D-periodicities, and the changes were compared both within the same fibril bundle and between fibril bundles. D-periodicities increased due to both increased strain and increasing numbers of fatigue cycles. Although no significant difference in D-periodicity lengthening was found between fibril bundles, the lengthening of D-periodicity correlated strongly with the overall tendon mechanical changes. The accurate quantification of fibril elongation in response to macroscopic applied strain assisted in assessing the complex structure-function relationship in Achilles tendons.
Collapse
Affiliation(s)
- Anas K Al Makhzoomi
- School of Allied Health, Faculty of Health Science, Curtin University, Perth, Western Australia, Australia
| | - Thomas B Kirk
- School of Science, Engineering and Technology, RMIT University Vietnam, Ho Chi Minh City, Vietnam
| | - Garry T Allison
- Associate Deputy Vice-Chancellor, Research Excellence, Curtin University, Perth, Western Australia, Australia
| |
Collapse
|
39
|
Leighton MP, Rutenberg AD, Kreplak L. D-band strain underestimates fibril strain for twisted collagen fibrils at low strains. J Mech Behav Biomed Mater 2021; 124:104854. [PMID: 34601435 DOI: 10.1016/j.jmbbm.2021.104854] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 08/01/2021] [Accepted: 09/19/2021] [Indexed: 11/29/2022]
Abstract
Collagen fibrils are the main structural component of load-bearing tissues such as tendons, ligaments, skin, the cornea of the eye, and the heart. The D-band of collagen fibrils is an axial periodic density modulation that can be easily characterized by tissue-level X-ray scattering. During mechanical testing, D-band strain is often used as a proxy for fibril strain. However, this approach ignores the coupling between strain and molecular tilt. We examine the validity of this approximation using an elastomeric collagen fibril model that includes both the D-band and a molecular tilt field. In the low strain regime, we show that the D-band strain substantially underestimates fibril strain for strongly twisted collagen fibrils - such as fibrils from skin or corneal tissue.
Collapse
Affiliation(s)
- Matthew P Leighton
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, B3H 4R2, Nova Scotia, Canada; Department of Physics, Simon Fraser University, Burnaby, V5A 1S6, British Columbia, Canada
| | - Andrew D Rutenberg
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, B3H 4R2, Nova Scotia, Canada.
| | - Laurent Kreplak
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, B3H 4R2, Nova Scotia, Canada
| |
Collapse
|
40
|
Al Makhzoomi AK, Kirk TB, Dye DE, Allison GT. The influence of glycosaminoglycan proteoglycan side chains on tensile force transmission and the nanostructural properties of Achilles tendons. Microsc Res Tech 2021; 85:233-243. [PMID: 34390286 DOI: 10.1002/jemt.23899] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Revised: 07/16/2021] [Accepted: 07/25/2021] [Indexed: 01/13/2023]
Abstract
This study investigates the nanostructural mechanisms that lie behind load transmission in tendons and the role of glycosaminoglycans (GAGs) in the transmission of force in the tendon extracellular matrix. The GAGs in white New Zealand rabbit Achilles tendons were enzymatically depleted, and the tendons subjected to cyclic loading at 6% strain for up to 2 hr. A nanoscale morphometric assessment of fibril deformation under strain was linked with the decline in the tendon macroscale mechanical properties. An atomic force microscope (AFM) was employed to characterize the D-periodicity within and between fibril bundles (WFB and BFB, respectively). By the end of the second hour of the applied strain, the WFB and BFB D-periodicities had significantly increased in the GAG-depleted group (29% increase compared with 15% for the control, p < .0001). No statistically significant differences were found between WFB and BFB D-periodicities in either the control or GAG-depleted groups, suggesting that mechanical load in Achilles tendons is uniformly distributed and fairly homogenous among the WFB and BFB networks. The results of this study have provided evidence of a cycle-dependent mechanism of damage accumulation. The accurate quantification of fibril elongation (measured as the WFB and BFB D-periodicity lengths) in response to macroscopic applied strain has assisted in assessing the complex structure-function relationship in Achilles tendon.
Collapse
Affiliation(s)
- Anas K Al Makhzoomi
- School of Allied Health, Faculty of Health Science, Curtin University, Perth, Western Australia, Australia
| | - Thomas B Kirk
- Dean, School of Science, Engineering and Technology, RMIT University Vietnam, Ho Chi Minh City, Vietnam
| | - Danielle E Dye
- Curtin Medical School, Faculty of Health Sciences, Curtin University, Perth, Western Australia, Australia
| | - Garry T Allison
- Associate Deputy Vice-Chancellor -Research Excellence - Curtin University, Perth, Western Australia, Australia, Member Board of Directors; Sports Medicine Australia, Perth
| |
Collapse
|
41
|
Obarska-Kosinska A, Rennekamp B, Ünal A, Gräter F. ColBuilder: A server to build collagen fibril models. Biophys J 2021; 120:3544-3549. [PMID: 34265261 DOI: 10.1016/j.bpj.2021.07.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 05/21/2021] [Accepted: 07/07/2021] [Indexed: 11/17/2022] Open
Abstract
Type I collagen is the main structural component of many tissues in the human body. It provides excellent mechanical properties to connective tissue and acts as a protein interaction hub. There is thus a wide interest in understanding the properties and diverse functions of type I collagen at the molecular level. A precondition is an atomistic collagen I structure as it occurs in native tissue. To this end, we built full-atom models of cross-linked collagen fibrils by integrating the low-resolution structure of collagen fibril available from x-ray fiber diffraction with high-resolution structures of short collagen-like peptides from x-ray crystallography and mass spectrometry data. We created a Web resource of collagen models for 20 different species with a large variety of cross-link types and localization within the fibril to facilitate structure-based analyses and simulations of type I collagen in health and disease. To easily enable simulations, we provide parameters of the modeled cross-links for an Amber force field. The repository of collagen models is available at https://colbuilder.h-its.org.
Collapse
Affiliation(s)
- Agnieszka Obarska-Kosinska
- Heidelberg Institute for Theoretical Studies, Heidelberg, Germany; Hamburg Unit c/o DESY, European Molecular Biology Laboratory, Hamburg, Germany
| | - Benedikt Rennekamp
- Heidelberg Institute for Theoretical Studies, Heidelberg, Germany; Max Planck School Matter-to-Life (MtL), Heidelberg, Germany; Interdisciplinary Center for Scientific Computing, Heidelberg University, Heidelberg, Germany
| | - Aysecan Ünal
- Heidelberg Institute for Theoretical Studies, Heidelberg, Germany; Max Planck School Matter-to-Life (MtL), Heidelberg, Germany
| | - Frauke Gräter
- Heidelberg Institute for Theoretical Studies, Heidelberg, Germany; Max Planck School Matter-to-Life (MtL), Heidelberg, Germany; Interdisciplinary Center for Scientific Computing, Heidelberg University, Heidelberg, Germany.
| |
Collapse
|
42
|
A microstructural model of tendon failure. J Mech Behav Biomed Mater 2021; 122:104665. [PMID: 34311323 DOI: 10.1016/j.jmbbm.2021.104665] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 05/27/2021] [Accepted: 06/25/2021] [Indexed: 02/07/2023]
Abstract
Collagen fibrils are the most important structural component of tendons. Their crimped structure and parallel arrangement within the tendon lead to a distinctive non-linear stress-strain curve when a tendon is stretched. Microstructural models can be used to relate microscale collagen fibril mechanics to macroscale tendon mechanics, allowing us to identify the mechanisms behind each feature present in the stress-strain curve. Most models in the literature focus on the elastic behaviour of the tendon, and there are few which model beyond the elastic limit without introducing phenomenological parameters. We develop a model, built upon a collagen recruitment approach, that only contains microstructural parameters. We split the stress in the fibrils into elastic and plastic parts, and assume that the fibril yield stretch and rupture stretch are each described by a distribution function, rather than being single-valued. By changing the shapes of the distributions and their regions of overlap, we can produce macroscale tendon stress-strain curves that generate the full range of features observed experimentally, including those that could not be explained using existing models. These features include second linear regions occurring after the tendon has yielded, and step-like failure behaviour present after the stress has peaked. When we compare with an existing model, we find that our model reduces the average root mean squared error from 4.53MPa to 2.29MPa, and the resulting parameter values are closer to those found experimentally. Since our model contains only parameters that have a direct physical interpretation, it can be used to predict how processes such as ageing, disease, and injury affect the mechanical behaviour of tendons, provided we can quantify the effects of these processes on the microstructure.
Collapse
|
43
|
Rezvani Ghomi E, Nourbakhsh N, Akbari Kenari M, Zare M, Ramakrishna S. Collagen-based biomaterials for biomedical applications. J Biomed Mater Res B Appl Biomater 2021; 109:1986-1999. [PMID: 34028179 DOI: 10.1002/jbm.b.34881] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 04/24/2021] [Accepted: 05/15/2021] [Indexed: 12/19/2022]
Abstract
Collagen is an insoluble fibrous protein that composes the extracellular matrix in animals. Although collagen has been used as a biomaterial since 1881, the properties and the complex structure of collagen are still extensive study subjects worldwide. In this article, several topics of importance for understanding collagen research are reviewed starting from its historical milestones, followed by the description of the collagen superfamily and its complex structures, with a focus on type I collagen. Subsequently, some of the superior properties of collagen-based biomaterials, such as biocompatibility, biodegradability, mechanical properties, and cell activities, are pinpointed. These properties make collagen applicable in biomedicine, such as wound healing, tissue engineering, surface coating of medical devices, and skin supplementation. Moreover, some antimicrobial strategies and the general host tissue responses regarding collagen as a biomaterial are presented. Finally, the current status and clinical application of the three-dimensional (3D) printing techniques for the fabrication of collagen-based scaffolds and the reconstruction of the human heart's constituents, such as capillary structures or even the entire organ, are discussed. Besides, an overall outlook for the future of this unique biomaterial is provided.
Collapse
Affiliation(s)
- Erfan Rezvani Ghomi
- Center for Nanotechnology and Sustainability, Department of Mechanical Engineering, National University of Singapore, Singapore, Singapore
| | - Nooshin Nourbakhsh
- Yong Loo Lin School of Medicine, Department of Medicine, National University of Singapore, Singapore, Singapore
| | | | - Mina Zare
- Center for Nanotechnology and Sustainability, Department of Mechanical Engineering, National University of Singapore, Singapore, Singapore
| | - Seeram Ramakrishna
- Center for Nanotechnology and Sustainability, Department of Mechanical Engineering, National University of Singapore, Singapore, Singapore
| |
Collapse
|
44
|
Lama M, Raveendranathan B, Brun J, Fernandes FM, Boissière C, Nassif N, Marcellan A. Biomimetic Tough Gels with Weak Bonds Unravel the Role of Collagen from Fibril to Suprafibrillar Self-Assembly. Macromol Biosci 2021; 21:e2000435. [PMID: 33881218 DOI: 10.1002/mabi.202000435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 03/04/2021] [Indexed: 11/10/2022]
Abstract
Biological tissues rich in type I collagen exhibit specific hierarchical fibrillar structures together with remarkable mechanical toughness. However, the role of collagen alone in their mechanical response at different structural levels is not fully understood. Here, it is proposed to rationalize such challenging interplay from a materials science perspective through the subtle control of this protein self-assembly in vitro. It is relied on a spray-processing approach to readily use the collagen phase diagram and set a palette of biomimetic self-assembled collagen gels in terms of suprafibrillar organization. Their mechanical responses unveil the involvement of mechanisms occurring either at fibrillar or suprafibrillar scales. Noticeably, both modulus at early stage of deformations and tensile toughness probe the suprafibrillar organization, while durability under cyclic loading and stress relaxation reflect mechanisms at the fibril level. By changing the physicochemical environment, the interfibrillar interactions are modified toward more biomimetic mechanical responses. The possibility of making tissue-like materials with versatile compositions and toughness opens perspectives in tissue engineering.
Collapse
Affiliation(s)
- Milena Lama
- Laboratoire Chimie de la Matière Condensée de Paris, Collège de France, Sorbonne Université, CNRS, 4 Place Jussieu, Paris, F-75005, France.,Sciences et Ingénierie de la Matière Molle, ESPCI Paris, PSL University, CNRS, Sorbonne Université, 10 rue Vauquelin, Paris, F-75005, France
| | - Biravena Raveendranathan
- Laboratoire Chimie de la Matière Condensée de Paris, Collège de France, Sorbonne Université, CNRS, 4 Place Jussieu, Paris, F-75005, France
| | - Julie Brun
- Laboratoire Chimie de la Matière Condensée de Paris, Collège de France, Sorbonne Université, CNRS, 4 Place Jussieu, Paris, F-75005, France.,Sciences et Ingénierie de la Matière Molle, ESPCI Paris, PSL University, CNRS, Sorbonne Université, 10 rue Vauquelin, Paris, F-75005, France
| | - Francisco M Fernandes
- Laboratoire Chimie de la Matière Condensée de Paris, Collège de France, Sorbonne Université, CNRS, 4 Place Jussieu, Paris, F-75005, France
| | - Cédric Boissière
- Laboratoire Chimie de la Matière Condensée de Paris, Collège de France, Sorbonne Université, CNRS, 4 Place Jussieu, Paris, F-75005, France
| | - Nadine Nassif
- Laboratoire Chimie de la Matière Condensée de Paris, Collège de France, Sorbonne Université, CNRS, 4 Place Jussieu, Paris, F-75005, France
| | - Alba Marcellan
- Sciences et Ingénierie de la Matière Molle, ESPCI Paris, PSL University, CNRS, Sorbonne Université, 10 rue Vauquelin, Paris, F-75005, France.,Institut Universitaire de France (IUF), 1, rue Descartes, Paris, F-75005, France
| |
Collapse
|
45
|
Dremin V, Marcinkevics Z, Zherebtsov E, Popov A, Grabovskis A, Kronberga H, Geldnere K, Doronin A, Meglinski I, Bykov A. Skin Complications of Diabetes Mellitus Revealed by Polarized Hyperspectral Imaging and Machine Learning. IEEE TRANSACTIONS ON MEDICAL IMAGING 2021; 40:1207-1216. [PMID: 33406038 DOI: 10.1109/tmi.2021.3049591] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Aging and diabetes lead to protein glycation and cause dysfunction of collagen-containing tissues. The accompanying structural and functional changes of collagen significantly contribute to the development of various pathological malformations affecting the skin, blood vessels, and nerves, causing a number of complications, increasing disability risks and threat to life. In fact, no methods of non-invasive assessment of glycation and associated metabolic processes in biotissues or prediction of possible skin complications, e.g., ulcers, currently exist for endocrinologists and clinical diagnosis. In this publication, utilizing emerging photonics-based technology, innovative solutions in machine learning, and definitive physiological characteristics, we introduce a diagnostic approach capable of evaluating the skin complications of diabetes mellitus at the very earlier stage. The results of the feasibility studies, as well as the actual tests on patients with diabetes and healthy volunteers, clearly show the ability of the approach to differentiate diabetic and control groups. Furthermore, the developed in-house polarization-based hyperspectral imaging technique accomplished with the implementation of the artificial neural network provides new horizons in the study and diagnosis of age-related diseases.
Collapse
|
46
|
Effects of oxidation on the structure of collagen fibers of sea cucumber (Apostichopus japonicus) body wall during thermal processing. Lebensm Wiss Technol 2021. [DOI: 10.1016/j.lwt.2020.110528] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
47
|
Kittana N, Assali M, Zimmermann WH, Liaw N, Santos GL, Rehman A, Lutz S. Modulating the Biomechanical Properties of Engineered Connective Tissues by Chitosan-Coated Multiwall Carbon Nanotubes. Int J Nanomedicine 2021; 16:989-1000. [PMID: 33633447 PMCID: PMC7901244 DOI: 10.2147/ijn.s289107] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 01/20/2021] [Indexed: 01/08/2023] Open
Abstract
Background Under certain conditions, the physiological repair of connective tissues might fail to restore the original structure and function. Optimized engineered connective tissues (ECTs) with biophysical properties adapted to the target tissue could be used as a substitution therapy. This study aimed to investigate the effect of ECT enforcement by a complex of multiwall carbon nanotubes with chitosan (C-MWCNT) to meet in vivo demands. Materials and Methods ECTs were constructed from human foreskin fibroblasts (HFF-1) in collagen type I and enriched with the three different percentages 0.025, 0.05 and 0.1% of C-MWCNT. Characterization of the physical properties was performed by biomechanical studies using unidirectional strain. Results Supplementation with 0.025% C-MWCNT moderately increased the tissue stiffness, reflected by Young’s modulus, compared to tissues without C-MWCNT. Supplementation of ECTs with 0.1% C-MWCNT reduced tissue contraction and increased the elasticity and the extensibility, reflected by the yield point and ultimate strain, respectively. Consequently, the ECTs with 0.1% C-MWCNT showed a higher resilience and toughness as control tissues. Fluorescence tissue imaging demonstrated the longitudinal alignment of all cells independent of the condition. Conclusion Supplementation with C-MWCNT can enhance the biophysical properties of ECTs, which could be advantageous for applications in connective tissue repair.
Collapse
Affiliation(s)
- Naim Kittana
- Department of Biomedical Sciences, Faculty of Medicine & Health Sciences, An-Najah National University, Nablus, Palestine
| | - Mohyeddin Assali
- Department of Pharmacy, Faculty of Medicine & Health Sciences, An-Najah National University, Nablus, Palestine
| | - Wolfram-Hubertus Zimmermann
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen, Germany.,DZHK (German Center for Cardiovascular Research) Partner Site Göttingen, Göttingen, Germany
| | - Norman Liaw
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen, Germany.,DZHK (German Center for Cardiovascular Research) Partner Site Göttingen, Göttingen, Germany
| | - Gabriela Leao Santos
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen, Germany.,DZHK (German Center for Cardiovascular Research) Partner Site Göttingen, Göttingen, Germany
| | - Abdul Rehman
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen, Germany.,DZHK (German Center for Cardiovascular Research) Partner Site Göttingen, Göttingen, Germany
| | - Susanne Lutz
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen, Germany.,DZHK (German Center for Cardiovascular Research) Partner Site Göttingen, Göttingen, Germany
| |
Collapse
|
48
|
Barrett JM, Fewster KM, Cudlip AC, Dickerson CR, Callaghan JP. The rate of tendon failure in a collagen fibre recruitment-based model. J Mech Behav Biomed Mater 2020; 115:104273. [PMID: 33373959 DOI: 10.1016/j.jmbbm.2020.104273] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 12/08/2020] [Accepted: 12/12/2020] [Indexed: 11/30/2022]
Abstract
Accurate characterization of the mechanical response of collagenous tissues is critical for investigations into mechanisms of soft tissue injury. These tissues are inherently viscoelastic, exhibiting strain-rate dependent stiffnesses, creep, and stress-relaxation. The strain-rate features of the failure portion of the stress-strain curve are less well developed. Collagen-distribution based models are improving and capable of reproducing the non-linear aspects of the elastic response of soft tissues, but still require parameterization of failure regions. Therefore, the purpose of this investigation, was to determine whether the parameters characterizing the rate of damage accumulation in a collagen-distribution model are proportional to strain rate. Fifty rat tail tendons were subjected to one of five different strain rates (0.01, 0.05, 0.1, 0.15, 0.20 s-1) until failure in an uni-axial strain test. To test the hypothesis that the parameters associated with damage rate are proportional to strain rate, a collagen distribution model was employed with the parameters describing the rate of fibre damage being obtained by least-squares and regressed against the strain rate. The breaking function was found to be proportional to strain rate, with a proportionality constant of 60.7 s-1. Properties characterizing the failure portion of the stress-strain curves for rat tail tendons are also reported. The Young's Modulus did not vary with strain rate and was found to be 103.3 ± 49.5 MPa. Similarly, failure stresses and strains did not vary across the strain rates tested, and were 15.6 ± 6.1 MPa and 32.2 ± 9.1%, respectively.
Collapse
Affiliation(s)
- Jeff M Barrett
- University of Waterloo, Department of Kinesiology, Canada
| | | | - Alan C Cudlip
- University of Waterloo, Department of Kinesiology, Canada
| | | | | |
Collapse
|
49
|
Lin AH, Allan AN, Zitnay JL, Kessler JL, Yu SM, Weiss JA. Collagen denaturation is initiated upon tissue yield in both positional and energy-storing tendons. Acta Biomater 2020; 118:153-160. [PMID: 33035697 DOI: 10.1016/j.actbio.2020.09.056] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 09/04/2020] [Accepted: 09/30/2020] [Indexed: 12/12/2022]
Abstract
Tendons are collagenous soft tissues that transmit loads between muscles and bones. Depending on their anatomical function, tendons are classified as positional or energy-storing with differing biomechanical and biochemical properties. We recently demonstrated that during monotonic stretch of positional tendons, permanent denatured collagen begins accumulating upon departing the linear region of the stress-strain curve. However, it is unknown if this observation is true during mechanical overload of other types of tendons. Therefore, the purpose of this study was to investigate the onset of collagen denaturation relative to applied strain, and whether it differs between the two tendon types. Rat tail tendon (RTT) fascicles and rat flexor digitorum longus (FDL) tendons represented positional and energy-storing tendons, respectively. The samples were stretched to incremental levels of strain, then stained with fluorescently labeled collagen hybridizing peptides (CHPs); the CHP fluorescence was measured to quantify denatured collagen. Denatured collagen in both positional and energy-storing tendons began to increase at the yield strain, upon leaving the linear region of the stress-strain curve as the sample started to permanently deform. Despite significant differences between the two tendon types, it appears that collagen denaturation is initiated at tissue yield during monotonic stretch, and the fundamental mechanism of failure is the same for the two types of tendons. At tissue failure, positional tendons had double the percentage of denatured collagen compared to energy-storing tendons, with no difference between 0% control groups. These results help to elucidate the etiology of subfailure injury and rupture in functionally distinct tendons.
Collapse
Affiliation(s)
- Allen H Lin
- Department of Biomedical Engineering, University of Utah, United States; Scientific Computing and Imaging Institute, University of Utah, United States
| | - Alexandra N Allan
- Department of Biomedical Engineering, University of Utah, United States; Scientific Computing and Imaging Institute, University of Utah, United States
| | - Jared L Zitnay
- Department of Biomedical Engineering, University of Utah, United States; Scientific Computing and Imaging Institute, University of Utah, United States
| | - Julian L Kessler
- Department of Biomedical Engineering, University of Utah, 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.
| |
Collapse
|
50
|
Peterson BE, Szczesny SE. Dependence of tendon multiscale mechanics on sample gauge length is consistent with discontinuous collagen fibrils. Acta Biomater 2020; 117:302-309. [PMID: 33010516 DOI: 10.1016/j.actbio.2020.09.046] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 09/22/2020] [Accepted: 09/24/2020] [Indexed: 12/27/2022]
Abstract
While collagen fibrils are understood to be the primary load-bearing elements in tendon, controversy still exists on how fibrils functionally transmit load from muscle to bone. Specifically, it's unclear whether fibrils are structurally continuous along the tendon length and bear load independently, or if they are discontinuous and transfer load through interfibrillar shear forces. To address this question, we investigated whether the multiscale mechanics of rat tail tendon fascicles is dependent on sample gauge length. We hypothesized that as the grip-to-grip length is reduced and approaches the length of the collagen fibrils, tendon fascicles will adopt a multiscale mechanical response consistent with structurally continuous fibrils. Our findings show that, for gauge lengths of 20 mm or greater, the local fibril strains are less than the bulk tissue strains, which can be explained by relative sliding between discontinuous collagen fibrils. In contrast, at a 5 mm gauge length, the fibril strains are equivalent to the applied tissue strains, suggesting that the collagen fibrils are structurally continuous between the grips. Additionally, the macroscale tissue modulus is increased at gauge lengths of 5 and 10 mm. Together, these data support the hypothesis that collagen fibrils in rat tail tendon fascicles are discontinuous and also suggest that their length is between 5 and 10 mm. This fundamental information regarding tendon structure-function relationships underscores the importance of the tissue components that transmit load between fibrils and is critical for understanding tendon pathology as well as establishing structural benchmarks for suitable tissue engineered replacements.
Collapse
|