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de Alcântara ACS, Felix LC, Galvão DS, Sollero P, Skaf MS. The Role of the Extrafibrillar Volume on the Mechanical Properties of Molecular Models of Mineralized Bone Microfibrils. ACS Biomater Sci Eng 2023; 9:230-245. [PMID: 36484626 DOI: 10.1021/acsbiomaterials.2c00728] [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: 12/13/2022]
Abstract
Bones are responsible for body support, structure, motion, and several other functions that enable and facilitate life for many different animal species. They exhibit a complex network of distinct physical structures and mechanical properties, which ultimately depend on the fraction of their primary constituents at the molecular scale. However, the relationship between structure and mechanical properties in bones are still not fully understood. Here, we investigate structural and mechanical properties of all-atom bone molecular models composed of type-I collagen, hydroxyapatite (HA), and water by means of fully atomistic molecular dynamics simulations. Our models encompass an extrafibrillar volume (EFV) and consider mineral content in both the EFV and intrafibrillar volume (IFV), consistent with experimental observations. We investigate solvation structures and elastic properties of bone microfibril models with different degrees of mineralization, ranging from highly mineralized to weakly mineralized and nonmineralized models. We find that the local tetrahedral order of water is lost in similar ways in the EFV and IFV regions for all HA containing models, as calcium and phosphate ions are strongly coordinated with water molecules. We also subject our models to tensile loads and analyze the spatial stress distribution over the nanostructure of the material. Our results show that both mineral and water contents accumulate significantly higher stress levels, most notably in the EFV, thus revealing that this region, which has been only recently incorporated in all-atom molecular models, is fundamental for studying the mechanical properties of bones at the nanoscale. Furthermore, our results corroborate the well-established finding that high mineral content makes bone stiffer.
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Affiliation(s)
- Amadeus C S de Alcântara
- Department of Computational Mechanics, School of Mechanical Engineering, University of Campinas, Campinas13083-860, SPBrazil.,Center for Computing in Engineering & Sciences, CCES, University of Campinas, Campinas13083-861, SPBrazil
| | - Levi C Felix
- Center for Computing in Engineering & Sciences, CCES, University of Campinas, Campinas13083-861, SPBrazil.,Department of Applied Physics, Gleb Wataghin Institute of Physics, University of Campinas, Campinas13083-859, SPBrazil
| | - Douglas S Galvão
- Center for Computing in Engineering & Sciences, CCES, University of Campinas, Campinas13083-861, SPBrazil.,Department of Applied Physics, Gleb Wataghin Institute of Physics, University of Campinas, Campinas13083-859, SPBrazil
| | - Paulo Sollero
- Department of Computational Mechanics, School of Mechanical Engineering, University of Campinas, Campinas13083-860, SPBrazil.,Center for Computing in Engineering & Sciences, CCES, University of Campinas, Campinas13083-861, SPBrazil
| | - Munir S Skaf
- Center for Computing in Engineering & Sciences, CCES, University of Campinas, Campinas13083-861, SPBrazil.,Institute of Chemistry, University of Campinas, Campinas13083-970, SPBrazil
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Devising Bone Molecular Models at the Nanoscale: From Usual Mineralized Collagen Fibrils to the First Bone Fibers Including Hydroxyapatite in the Extra-Fibrillar Volume. MATERIALS 2022; 15:ma15062274. [PMID: 35329726 PMCID: PMC8955169 DOI: 10.3390/ma15062274] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/08/2022] [Accepted: 03/17/2022] [Indexed: 02/04/2023]
Abstract
At the molecular scale, bone is mainly constituted of type-I collagen, hydroxyapatite, and water. Different fractions of these constituents compose different composite materials that exhibit different mechanical properties at the nanoscale, where the bone is characterized as a fiber, i.e., a bundle of mineralized collagen fibrils surrounded by water and hydroxyapatite in the extra-fibrillar volume. The literature presents only models that resemble mineralized collagen fibrils, including hydroxyapatite in the intra-fibrillar volume only, and lacks a detailed prescription on how to devise such models. Here, we present all-atom bone molecular models at the nanoscale, which, differently from previous bone models, include hydroxyapatite both in the intra-fibrillar volume and in the extra-fibrillar volume, resembling fibers in bones. Our main goal is to provide a detailed prescription on how to devise such models with different fractions of the constituents, and for that reason, we have made step-by-step scripts and files for reproducing these models available. To validate the models, we assessed their elastic properties by performing molecular dynamics simulations that resemble tensile tests, and compared the computed values against the literature (both experimental and computational results). Our results corroborate previous findings, as Young’s Modulus values increase with higher fractions of hydroxyapatite, revealing all-atom bone models that include hydroxyapatite in both the intra-fibrillar volume and in the extra-fibrillar volume as a path towards realistic bone modeling at the nanoscale.
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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.
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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
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Varma S, Orgel JPRO, Schieber JD. Contrasting Local and Macroscopic Effects of Collagen Hydroxylation. Int J Mol Sci 2021; 22:ijms22169068. [PMID: 34445791 PMCID: PMC8396666 DOI: 10.3390/ijms22169068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 08/16/2021] [Accepted: 08/20/2021] [Indexed: 11/16/2022] Open
Abstract
Collagen is heavily hydroxylated. Experiments show that proline hydroxylation is important to triple helix (monomer) stability, fibril assembly, and interaction of fibrils with other molecules. Nevertheless, experiments also show that even without hydroxylation, type I collagen does assemble into its native D-banded fibrillar structure. This raises two questions. Firstly, even though hydroxylation removal marginally affects macroscopic structure, how does such an extensive chemical change, which is expected to substantially reduce hydrogen bonding capacity, affect local structure? Secondly, how does such a chemical perturbation, which is expected to substantially decrease electrostatic attraction between monomers, affect collagen's mechanical properties? To address these issues, we conduct a benchmarked molecular dynamics study of rat type I fibrils in the presence and absence of hydroxylation. Our simulations reproduce the experimental observation that hydroxylation removal has a minimal effect on collagen's D-band length. We also find that the gap-overlap ratio, monomer width and monomer length are minimally affected. Surprisingly, we find that de-hydroxylation also has a minor effect on the fibril's Young's modulus, and elastic stress build up is also accompanied by tightening of triple-helix windings. In terms of local structure, de-hydroxylation does result in a substantial drop (23%) in inter-monomer hydrogen bonding. However, at the same time, the local structures and inter-monomer hydrogen bonding networks of non-hydroxylated amino acids are also affected. It seems that it is this intrinsic plasticity in inter-monomer interactions that preclude fibrils from undergoing any large changes in macroscopic properties. Nevertheless, changes in local structure can be expected to directly impact collagen's interaction with extra-cellular matrix proteins. In general, this study highlights a key challenge in tissue engineering and medicine related to mapping collagen chemistry to macroscopic properties but suggests a path forward to address it using molecular dynamics simulations.
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Affiliation(s)
- Sameer Varma
- Department of Cell Biology, Microbiology and Molecular Biology, Department of Physics, University of South Florida, Tampa, FL 33620, USA
- Correspondence:
| | - Joseph P. R. O. Orgel
- Department of Biology, Department of Physics, Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, IL 60616, USA;
| | - Jay D. Schieber
- Department of Chemical and Biological Engineering, Department of Physics, Illinois Institute of Technology, Chicago, IL 60616, USA;
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Yan LJ, Sun LC, Cao KY, Chen YL, Zhang LJ, Liu GM, Jin T, Cao MJ. Type I collagen from sea cucumber (Stichopus japonicus) and the role of matrix metalloproteinase-2 in autolysis. FOOD BIOSCI 2021. [DOI: 10.1016/j.fbio.2021.100959] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Ristaniemi A, Regmi D, Mondal D, Torniainen J, Tanska P, Stenroth L, Finnilä MAJ, Töyräs J, Korhonen RK. Structure, composition and fibril-reinforced poroviscoelastic properties of bovine knee ligaments and patellar tendon. J R Soc Interface 2021; 18:20200737. [PMID: 33499766 DOI: 10.1098/rsif.2020.0737] [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] [Indexed: 12/24/2022] Open
Abstract
Tissue-level stress-relaxation of ligaments and tendons in the toe region is characterized by fast and long-term relaxations and an increase in relaxation magnitude with strain. Characterizing the compositional and structural origins of these phenomena helps in the understanding of mechanisms of ligament and tendon function and adaptation in health and disease. A three-step tensile stress-relaxation test was conducted on dumbbell-shaped pieces of bovine knee ligaments and patellar tendon (PT) (n = 10 knees). Their mechanical behaviour was characterized by a fibril-reinforced poroviscoelastic material model, able to describe characteristic times and magnitudes of fast and long-term relaxations. The crimp angle and length of tissues were measured with polarized light microscopy, while biochemical contents were determined by colorimetric biochemical methods. The long-term relaxation time was longer in the anterior cruciate ligament (ACL) and PT compared with collateral ligaments (p < 0.05). High hydroxyproline content predicted greater magnitude and shorter time of both fast and long-term relaxation. High uronic acid content predicted longer time of long-term relaxation, whereas high crimp angle predicted higher magnitude of long-term relaxation. ACL and PT are better long-term stabilizers than collateral ligaments. The long-term relaxation behaviour is affected or implied by proteoglycans and crimp angle, possibly relating to slow structural reorganization of the tissue.
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Affiliation(s)
- Aapo Ristaniemi
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
| | - Dristi Regmi
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
| | - Diponkor Mondal
- Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland
| | - Jari Torniainen
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.,Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland
| | - Petri Tanska
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
| | - Lauri Stenroth
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
| | - Mikko A J Finnilä
- Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland
| | - Juha Töyräs
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.,Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland.,School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane, Australia
| | - Rami K Korhonen
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
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Zeng YY, Hu WP, Zuo YH, Wang XR, Zhang J. Altered serum levels of type I collagen turnover indicators accompanied by IL-6 and IL-8 release in stable COPD. Int J Chron Obstruct Pulmon Dis 2019; 14:163-168. [PMID: 30655663 PMCID: PMC6322508 DOI: 10.2147/copd.s188139] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND COPD, characterized by chronic inflammation and airway remodeling, has significant pathological alterations in composition and deposition of the extracellular matrix. The expression of procollagen 1 C-terminal peptide (PICP) and collagen type 1 C-terminal telopeptide (ICTP), two major by-products in the synthesis and degradation of collagen, was shown to be positively correlated with inflammatory mediator levels in previous studies. PURPOSE In this study, we investigated whether the serum concentrations of PICP and ICTP were associated with the inflammation level for patients with stable COPD. PATIENTS AND METHODS We collected serum samples from 25 control subjects and 20 patients with stable COPD from December 2011 to October 2012 in Shanghai Zhongshan Hospital and Shanghai Dahua Hospital. We determined concentrations of PICP, ICTP, C-reactive protein (CRP), IL-6, IL-8, and tumor necrosis factor (TNF)-α by using enzyme-linked immunosorbent assay methods. RESULTS Demographic characteristics were comparable between the two groups. In patients with stable COPD, serum levels of CRP, IL-6, IL-8, and TNF-α were all elevated compared to control subjects, but only changes of IL-6 achieved statistical significance. Serum concentration of PICP was significantly elevated in patients with COPD, and level of ICTP was slightly decreased. Moreover, serum concentrations of PICP were positively correlated with the levels of both IL-6 and IL-8. CONCLUSION The increased levels of serum PICP in COPD might indicate the condition of airway remodeling, and IL-6 and/or IL-8 might play an important role in stimulating collagen synthesis.
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Affiliation(s)
- Ying-Ying Zeng
- Department of Pulmonary Medicine, Zhongshan Hospital, Fudan University, Shanghai, China,
| | - Wei-Ping Hu
- Department of Pulmonary Medicine, Zhongshan Hospital, Fudan University, Shanghai, China,
| | - Yi-Hui Zuo
- Department of Pulmonary Medicine, Zhongshan Hospital, Fudan University, Shanghai, China,
| | - Xiao-Ru Wang
- Department of Pulmonary Medicine, Dahua Hospital, Shanghai, China
| | - Jing Zhang
- Department of Pulmonary Medicine, Zhongshan Hospital, Fudan University, Shanghai, China,
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