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Guvench O. Atomic-Resolution Experimental Structural Biology and Molecular Dynamics Simulations of Hyaluronan and Its Complexes. Molecules 2022; 27:7276. [PMID: 36364098 PMCID: PMC9658939 DOI: 10.3390/molecules27217276] [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: 08/26/2022] [Revised: 10/20/2022] [Accepted: 10/21/2022] [Indexed: 11/28/2023] Open
Abstract
This review summarizes the atomic-resolution structural biology of hyaluronan and its complexes available in the Protein Data Bank, as well as published studies of atomic-resolution explicit-solvent molecular dynamics simulations on these and other hyaluronan and hyaluronan-containing systems. Advances in accurate molecular mechanics force fields, simulation methods and software, and computer hardware have supported a recent flourish in such simulations, such that the simulation publications now outnumber the structural biology publications by an order of magnitude. In addition to supplementing the experimental structural biology with computed dynamic and thermodynamic information, the molecular dynamics studies provide a wealth of atomic-resolution information on hyaluronan-containing systems for which there is no atomic-resolution structural biology either available or possible. Examples of these summarized in this review include hyaluronan pairing with other hyaluronan molecules and glycosaminoglycans, with ions, with proteins and peptides, with lipids, and with drugs and drug-like molecules. Despite limitations imposed by present-day computing resources on system size and simulation timescale, atomic-resolution explicit-solvent molecular dynamics simulations have been able to contribute significant insight into hyaluronan's flexibility and capacity for intra- and intermolecular non-covalent interactions.
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Affiliation(s)
- Olgun Guvench
- Department of Pharmaceutical Sciences and Administration, School of Pharmacy, Westbrook College of Health Professions, University of New England, 716 Stevens Avenue, Portland, ME 04103, USA
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2
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Mihajlovic M, Rikkers M, Mihajlovic M, Viola M, Schuiringa G, Ilochonwu BC, Masereeuw R, Vonk L, Malda J, Ito K, Vermonden T. Viscoelastic Chondroitin Sulfate and Hyaluronic Acid Double-Network Hydrogels with Reversible Cross-Links. Biomacromolecules 2022; 23:1350-1365. [PMID: 35195399 PMCID: PMC8924925 DOI: 10.1021/acs.biomac.1c01583] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 02/11/2022] [Indexed: 12/13/2022]
Abstract
Viscoelastic hydrogels are gaining interest as they possess necessary requirements for bioprinting and injectability. By means of reversible, dynamic covalent bonds, it is possible to achieve features that recapitulate the dynamic character of the extracellular matrix. Dually cross-linked and double-network (DN) hydrogels seem to be ideal for the design of novel biomaterials and bioinks, as a wide range of properties required for mimicking advanced and complex tissues can be achieved. In this study, we investigated the fabrication of chondroitin sulfate/hyaluronic acid (CS/HA)-based DN hydrogels, in which two networks are interpenetrated and cross-linked with the dynamic covalent bonds of very different lifetimes. Namely, Diels-Alder adducts (between methylfuran and maleimide) and hydrazone bonds (between aldehyde and hydrazide) were chosen as cross-links, leading to viscoelastic hydrogels. Furthermore, we show that viscoelasticity and the dynamic character of the resulting hydrogels could be tuned by changing the composition, that is, the ratio between the two types of cross-links. Also, due to a very dynamic nature and short lifetime of hydrazone cross-links (∼800 s), the DN hydrogel is easily processable (e.g., injectable) in the first stages of gelation, allowing the material to be used in extrusion-based 3D printing. The more long-lasting and robust Diels-Alder cross-links are responsible for giving the network enhanced mechanical strength and structural stability. Being highly charged and hydrophilic, the cross-linked CS and HA enable a high swelling capacity (maximum swelling ratio ranging from 6 to 12), which upon confinement results in osmotically stiffened constructs, able to mimic the mechanical properties of cartilage tissue, with the equilibrium moduli ranging from 0.3 to 0.5 MPa. Moreover, the mesenchymal stromal cells were viable in the presence of the hydrogels, and the effect of the degradation products on the macrophages suggests their safe use for further translational applications. The DN hydrogels with dynamic covalent cross-links hold great potential for the development of novel smart and tunable viscoelastic materials to be used as biomaterial inks or bioinks in bioprinting and regenerative medicine.
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Affiliation(s)
- Marko Mihajlovic
- Department
of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, 3584 CG Utrecht, The Netherlands
- Department
of Biomedical Engineering, Eindhoven University
of Technology, 5612 AZ Eindhoven, The Netherlands
| | - Margot Rikkers
- Department
of Orthopaedics, University Medical Center Utrecht, Utrecht University, 3508
GA Utrecht, The Netherlands
| | - Milos Mihajlovic
- Department
of Pharmacology, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, 3584 CG Utrecht, The Netherlands
| | - Martina Viola
- Department
of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, 3584 CG Utrecht, The Netherlands
- Department
of Orthopaedics, University Medical Center Utrecht, Utrecht University, 3508
GA Utrecht, The Netherlands
| | - Gerke Schuiringa
- Department
of Biomedical Engineering, Eindhoven University
of Technology, 5612 AZ Eindhoven, The Netherlands
| | - Blessing C. Ilochonwu
- Department
of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, 3584 CG Utrecht, The Netherlands
| | - Rosalinde Masereeuw
- Department
of Pharmacology, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, 3584 CG Utrecht, The Netherlands
| | - Lucienne Vonk
- Department
of Orthopaedics, University Medical Center Utrecht, Utrecht University, 3508
GA Utrecht, The Netherlands
| | - Jos Malda
- Department
of Orthopaedics, University Medical Center Utrecht, Utrecht University, 3508
GA Utrecht, The Netherlands
- Department
of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, 3508
GA Utrecht, the Netherlands
| | - Keita Ito
- Department
of Biomedical Engineering, Eindhoven University
of Technology, 5612 AZ Eindhoven, The Netherlands
- Department
of Orthopaedics, University Medical Center Utrecht, Utrecht University, 3508
GA Utrecht, The Netherlands
| | - Tina Vermonden
- Department
of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, 3584 CG Utrecht, The Netherlands
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Horkay F, Basser PJ, Hecht AM, Geissler E. Ionic effects in semi-dilute biopolymer solutions: A small angle scattering study. J Chem Phys 2018; 149:163312. [PMID: 30384682 PMCID: PMC6910579 DOI: 10.1063/1.5028351] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 05/29/2018] [Indexed: 11/14/2022] Open
Abstract
Systematic investigations using neutron and X-ray small angle scattering in near-physiological salt solutions were made to reveal the effect of polymer concentration, pH, and calcium ion concentration on the structure of semi-dilute solutions of four model biopolymers [polyaspartic acid, DNA, chondroitin sulfate, and hyaluronic acid (HA)] representing typical backbone structures. In the low q range (<0.01 Å-1), the scattering response I(q) is dominated by scattering from large clusters. In the intermediate q range, I(q) varies approximately as q -1, exposing the linear nature of the scatterers. In these polyelectrolyte solutions, the correlation length L displays a power law dependence on the polymer concentration c that resembles that of neutral polymer solutions. L increases with increasing calcium chloride concentration and with decreasing pH. The effect of the different divalent cations, Ba, Mg, Ca, Sr, and Mn, on the structure of DNA solutions is practically identical. However, in mixed salt conditions at the same ionic strength, the combined effect of mono- and divalent counter-ions on the structure of the polymer solutions deviates significantly from additivity. Anomalous small angle X-ray scattering observations on both DNA and HA solutions reveal that the divalent strontium counter-ions form a tight sheath around the polymer chain. The shape of the divalent ion cloud is similar in these two systems.
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Affiliation(s)
- Ferenc Horkay
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 49 Convent Drive, Bethesda, Maryland 20892-5772, USA
| | - Peter J. Basser
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 49 Convent Drive, Bethesda, Maryland 20892-5772, USA
| | - Anne-Marie Hecht
- Laboratoire Interdisciplinaire de Physique CNRS, Université Grenoble Alpes, F-38402 Saint Martin d’Hères Cedex, France
| | - Erik Geissler
- Laboratoire Interdisciplinaire de Physique CNRS, Université Grenoble Alpes, F-38402 Saint Martin d’Hères Cedex, France
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4
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Arbelaez-Camargo D, Roig-Carreras M, García-Montoya E, Pérez-Lozano P, Miñarro-Carmona M, Ticó-Grau JR, Suñé-Negre JM. Osmolality predictive models of different polymers as tools in parenteral and ophthalmic formulation development. Int J Pharm 2018; 543:190-200. [PMID: 29604368 DOI: 10.1016/j.ijpharm.2018.03.052] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 03/23/2018] [Accepted: 03/27/2018] [Indexed: 12/20/2022]
Abstract
During the development of parenteral dosage forms, different physicochemical studies are required to ensure stable, effective and safe formulations. The osmolality of this kind of dosage forms should bear a close similarity to the body fluids to prevent local irritation, pain or even more significant side effects like endothelial damage. The osmotic studies performed in Polyethylene glycol 400 (PEG 400), Polyethylene glycol 4000 (PEG 4000), Poloxamer 407 (P407), Sodium Hyaluronate (SH), Chondroitin Sulphate Sodium (CS), Cremophor RH 40 (CRE40) and Polyvinyl alcohol (PVA) aqueous solutions, showed that the theoretical determination of the osmolality based on their molecular weight as the only determinant factor did not agree with the values obtained by the measurement of colligative properties such as the freezing point depression. The data obtained from this study and its analysis, provided predictive equations that can be used as tools in the primary development to estimate formulation's osmolality at different concentrations; and its evolution over a period at the hypothetical worst-case scenario of storage temperature.
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Affiliation(s)
- Diana Arbelaez-Camargo
- Pharmacy and Pharmaceutical Technology Department, Faculty of Pharmacy, University of Barcelona, Joan XXIII 27-32, CP 08028 Barcelona, Spain.
| | - Manel Roig-Carreras
- Pharmacy and Pharmaceutical Technology Department, Faculty of Pharmacy, University of Barcelona, Joan XXIII 27-32, CP 08028 Barcelona, Spain
| | - Encarna García-Montoya
- Pharmacy and Pharmaceutical Technology Department, Faculty of Pharmacy, University of Barcelona, Joan XXIII 27-32, CP 08028 Barcelona, Spain; Pharmacotherapy, Pharmacogenetics and Pharmaceutical Technology Research Group, IDIBELL-UB, Duran i Reynals Hospital, 3a level, Gran Via de l'Hospitalet 199, CP 08908 Hospitalet de Llobregat, Barcelona, Spain.
| | - Pilar Pérez-Lozano
- Pharmacy and Pharmaceutical Technology Department, Faculty of Pharmacy, University of Barcelona, Joan XXIII 27-32, CP 08028 Barcelona, Spain; Pharmacotherapy, Pharmacogenetics and Pharmaceutical Technology Research Group, IDIBELL-UB, Duran i Reynals Hospital, 3a level, Gran Via de l'Hospitalet 199, CP 08908 Hospitalet de Llobregat, Barcelona, Spain
| | - Montserrat Miñarro-Carmona
- Pharmacy and Pharmaceutical Technology Department, Faculty of Pharmacy, University of Barcelona, Joan XXIII 27-32, CP 08028 Barcelona, Spain; Pharmacotherapy, Pharmacogenetics and Pharmaceutical Technology Research Group, IDIBELL-UB, Duran i Reynals Hospital, 3a level, Gran Via de l'Hospitalet 199, CP 08908 Hospitalet de Llobregat, Barcelona, Spain
| | - Josep Ramon Ticó-Grau
- Pharmacy and Pharmaceutical Technology Department, Faculty of Pharmacy, University of Barcelona, Joan XXIII 27-32, CP 08028 Barcelona, Spain; Pharmacotherapy, Pharmacogenetics and Pharmaceutical Technology Research Group, IDIBELL-UB, Duran i Reynals Hospital, 3a level, Gran Via de l'Hospitalet 199, CP 08908 Hospitalet de Llobregat, Barcelona, Spain
| | - Josep Maria Suñé-Negre
- Pharmacy and Pharmaceutical Technology Department, Faculty of Pharmacy, University of Barcelona, Joan XXIII 27-32, CP 08028 Barcelona, Spain; Pharmacotherapy, Pharmacogenetics and Pharmaceutical Technology Research Group, IDIBELL-UB, Duran i Reynals Hospital, 3a level, Gran Via de l'Hospitalet 199, CP 08908 Hospitalet de Llobregat, Barcelona, Spain
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5
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Effect of crosslinking in cartilage-like collagen microstructures. J Mech Behav Biomed Mater 2016; 66:138-143. [PMID: 27866057 DOI: 10.1016/j.jmbbm.2016.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 10/03/2016] [Accepted: 10/14/2016] [Indexed: 11/20/2022]
Abstract
The mechanical performance of biological tissues is underpinned by a complex and finely balanced structure. Central to this is collagen, the most abundant protein in our bodies, which plays a dominant role in the functioning of tissues, and also in disease. Based on the collagen meshwork of articular cartilage, we have developed a bottom-up spring-node model of collagen and examined the effect of fibril connectivity, implemented by crosslinking, on mechanical behaviour. Although changing individual crosslink stiffness within an order of magnitude had no significant effect on modelling predictions, the density of crosslinks in a meshwork had a substantial impact on its behaviour. Highly crosslinked meshworks maintained a 'normal' configuration under loading, with stronger resistance to deformation and improved recovery relative to sparsely crosslinked meshwork. Stress on individual fibrils, however, was higher in highly crosslinked meshworks. Meshworks with low numbers of crosslinks reconfigured to disease-like states upon deformation and recovery. The importance of collagen interconnectivity may provide insight into the role of ultrastructure and its mechanics in the initiation, and early stages, of diseases such as osteoarthritis.
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Abstract
Treatment options for osteoarthritis (OA) beyond pain relief or total knee replacement are very limited. Because of this, attention has shifted to identifying which factors increase the risk of OA in vulnerable populations in order to be able to give recommendations to delay disease onset or to slow disease progression. The gold standard is then to use principles of risk management, first to provide subject-specific estimates of risk and then to find ways of reducing that risk. Population studies of OA risk based on statistical associations do not provide such individually tailored information. Here we argue that mechanistic models of cartilage tissue maintenance and damage coupled to statistical models incorporating model uncertainty, united within the framework of structural reliability analysis, provide an avenue for bridging the disciplines of epidemiology, cell biology, genetics and biomechanics. Such models promise subject-specific OA risk assessment and personalized strategies for mitigating or even avoiding OA. We illustrate the proposed approach with a simple model of cartilage extracellular matrix synthesis and loss regulated by daily physical activity.
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7
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Khanlari A, Suekama TC, Detamore MS, Gehrke SH. Structurally diverse and readily tunable photocrosslinked chondroitin sulfate based copolymers. ACTA ACUST UNITED AC 2015. [DOI: 10.1002/polb.23751] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Anahita Khanlari
- Department of Chemical and Petroleum Engineering; University of Kansas; Learned Hall, Room 4163 Lawrence Kansas 66045
| | - Tiffany C. Suekama
- Department of Chemical and Petroleum Engineering; University of Kansas; Learned Hall, Room 4163 Lawrence Kansas 66045
| | - Michael S. Detamore
- Department of Chemical and Petroleum Engineering; University of Kansas; Learned Hall, Room 4163 Lawrence Kansas 66045
- Bioengineering Program; University of Kansas; Lawrence Kansas 66045
| | - Stevin H. Gehrke
- Department of Chemical and Petroleum Engineering; University of Kansas; Learned Hall, Room 4163 Lawrence Kansas 66045
- Bioengineering Program; University of Kansas; Lawrence Kansas 66045
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8
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Short-term consolidation of articular cartilage in the long-term context of osteoarthritis. J Theor Biol 2015; 368:102-12. [DOI: 10.1016/j.jtbi.2015.01.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 12/04/2014] [Accepted: 01/04/2015] [Indexed: 01/18/2023]
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9
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Kolesnikov AL, Budkov YA, Nogovitsyn EA. Coarse-Grained Model of Glycosaminoglycans in Aqueous Salt Solutions. A Field-Theoretical Approach. J Phys Chem B 2014; 118:13037-49. [DOI: 10.1021/jp503749a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Andrei L. Kolesnikov
- Institut
fur Nichtklassische Chemie e.V., Universität Leipzig, 04109 Leipzig, Germany
- Department
of Physics, Ivanovo State University, Ermaka 39, 153025 Ivanovo, Russia
| | - Yurij A. Budkov
- Institute
of Solution Chemistry, Russian Academy of Sciences 153045, Academicheskaya 1, Ivanovo, Russia
- National Research University Higher School of Economics, 101000 Moscow, Russia
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10
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Travascio F, Eltoukhy M, Cami S, Asfour S. Altered mechano-chemical environment in hip articular cartilage: effect of obesity. Biomech Model Mechanobiol 2013; 13:945-59. [PMID: 24352367 DOI: 10.1007/s10237-013-0545-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 12/10/2013] [Indexed: 11/28/2022]
Abstract
The production of extracellular matrix (ECM) components of articular cartilage is regulated, among other factors, by an intercellular signaling mechanism mediated by the interaction of cell surface receptors (CSR) with insulin-like growth factor-1 (IGF-1). In ECM, the presence of binding proteins (IGFBP) hinders IGF-1 delivery to CSR. It has been reported that levels of IGF-1 and IGFBP in obese population are, respectively, lower and higher than those found in normal population. In this study, an experimental-numerical approach was adopted to quantify the effect of this metabolic alteration found in obese population on the homeostasis of femoral hip cartilage. A new computational model, based on the mechano-electrochemical mixture theory, was developed to describe competitive binding kinetics of IGF-1 with IGFBP and CSR, and associated glycosaminoglycan (GAG) biosynthesis. Moreover, a gait analysis was carried out on obese and normal subjects to experimentally characterize mechanical loads on hip cartilage during walking. This information was deployed into the model to account for effects of physiologically relevant tissue deformation on GAG production in ECM. Numerical simulations were performed to compare GAG biosynthesis in femoral hip cartilage of normal and obese subjects. Results indicated that the lower ratio of IGF-1 to IGFBP found in obese population reduces cartilage GAG concentration up to 18 % when compared to normal population. Moreover, moderate physical activity, such as walking, has a modest beneficial effect on GAG production. The findings of this study suggest that IGF-1/IGFBP metabolic unbalance should be accounted for when considering the association of obesity with hip osteoarthritis.
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Affiliation(s)
- Francesco Travascio
- Biomechanics Research Laboratory, Department of Industrial Engineering, College of Engineering, University of Miami, 1251 Memorial Drive, MEB 268, Coral Gables, FL, 33124-0621, USA
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11
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Smith DW, Gardiner BS, Davidson JB, Grodzinsky AJ. Computational model for the analysis of cartilage and cartilage tissue constructs. J Tissue Eng Regen Med 2013; 10:334-47. [PMID: 23784936 DOI: 10.1002/term.1751] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 02/18/2013] [Accepted: 03/19/2013] [Indexed: 11/11/2022]
Abstract
We propose a new non-linear poroelastic model that is suited to the analysis of soft tissues. In this paper the model is tailored to the analysis of cartilage and the engineering design of cartilage constructs. The proposed continuum formulation of the governing equations enables the strain of the individual material components within the extracellular matrix (ECM) to be followed over time, as the individual material components are synthesized, assembled and incorporated within the ECM or lost through passive transport or degradation. The material component analysis developed here naturally captures the effect of time-dependent changes of ECM composition on the deformation and internal stress states of the ECM. For example, it is shown that increased synthesis of aggrecan by chondrocytes embedded within a decellularized cartilage matrix initially devoid of aggrecan results in osmotic expansion of the newly synthesized proteoglycan matrix and tension within the structural collagen network. Specifically, we predict that the collagen network experiences a tensile strain, with a maximum of ~2% at the fixed base of the cartilage. The analysis of an example problem demonstrates the temporal and spatial evolution of the stresses and strains in each component of a self-equilibrating composite tissue construct, and the role played by the flux of water through the tissue.
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Affiliation(s)
- David W Smith
- School of Computer Science and Software Engineering, University of Western Australia, Crawley, WA, Australia
| | - Bruce S Gardiner
- School of Computer Science and Software Engineering, University of Western Australia, Crawley, WA, Australia
| | - John B Davidson
- School of Computer Science and Software Engineering, University of Western Australia, Crawley, WA, Australia
| | - Alan J Grodzinsky
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
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12
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Contribution of proteoglycan osmotic swelling pressure to the compressive properties of articular cartilage. Biophys J 2011; 101:916-24. [PMID: 21843483 DOI: 10.1016/j.bpj.2011.07.006] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 06/30/2011] [Accepted: 07/06/2011] [Indexed: 11/22/2022] Open
Abstract
The negatively charged proteoglycans (PG) provide compressive resistance to articular cartilage by means of their fixed charge density (FCD) and high osmotic pressure (π(PG)), and the collagen network (CN) provides the restraining forces to counterbalance π(PG). Our objectives in this work were to: 1), account for collagen intrafibrillar water when transforming biochemical measurements into a FCD-π(PG) relationship; 2), compute π(PG) and CN contributions to the compressive behavior of full-thickness cartilage during bovine growth (fetal, calf, and adult) and human adult aging (young and old); and 3), predict the effect of depth from the articular surface on π(PG) in human aging. Extrafibrillar FCD (FCD(EF)) and π(PG) increased with bovine growth due to an increase in CN concentration, whereas PG concentration was steady. This maturation-related increase was amplified by compression. With normal human aging, FCD(EF) and π(PG) decreased. The π(PG)-values were close to equilibrium stress (σ(EQ)) in all bovine and young human cartilage, but were only approximately half of σ(EQ) in old human cartilage. Depth-related variations in the strain, FCD(EF), π(PG), and CN stress profiles in human cartilage suggested a functional deterioration of the superficial layer with aging. These results suggest the utility of the FCD-π(PG) relationship for elucidating the contribution of matrix macromolecules to the biomechanical properties of cartilage.
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13
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Han L, Grodzinsky AJ, Ortiz C. Nanomechanics of the Cartilage Extracellular Matrix. ANNUAL REVIEW OF MATERIALS RESEARCH 2011; 41:133-168. [PMID: 22792042 PMCID: PMC3392687 DOI: 10.1146/annurev-matsci-062910-100431] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Cartilage is a hydrated biomacromolecular fiber composite located at the ends of long bones that enables proper joint lubrication, articulation, loading, and energy dissipation. Degradation of extracellular matrix molecular components and changes in their nanoscale structure greatly influence the macroscale behavior of the tissue and result in dysfunction with age, injury, and diseases such as osteoarthritis. Here, the application of the field of nanomechanics to cartilage is reviewed. Nanomechanics involves the measurement and prediction of nanoscale forces and displacements, intra- and intermolecular interactions, spatially varying mechanical properties, and other mechanical phenomena existing at small length scales. Experimental nanomechanics and theoretical nanomechanics have been applied to cartilage at varying levels of material complexity, e.g., nanoscale properties of intact tissue, the matrix associated with single cells, biomimetic molecular assemblies, and individual extracellular matrix biomolecules (such as aggrecan, collagen, and hyaluronan). These studies have contributed to establishing a fundamental mechanism-based understanding of native and engineered cartilage tissue function, quality, and pathology.
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Affiliation(s)
- Lin Han
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Alan J. Grodzinsky
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Christine Ortiz
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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14
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Hrabetová S, Masri D, Tao L, Xiao F, Nicholson C. Calcium diffusion enhanced after cleavage of negatively charged components of brain extracellular matrix by chondroitinase ABC. J Physiol 2009; 587:4029-49. [PMID: 19546165 DOI: 10.1113/jphysiol.2009.170092] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The concentration of extracellular calcium plays a critical role in synaptic transmission and neuronal excitability as well as other physiological processes. The time course and extent of local fluctuations in the concentration of this ion largely depend on its effective diffusion coefficient (D*) and it has been speculated that fixed negative charges on chondroitin sulphate proteoglycans (CSPGs) and other components of the extracellular matrix may influence calcium diffusion because it is a divalent cation. In this study we used ion-selective microelectrodes combined with pressure ejection or iontophoresis of ions from a micropipette to quantify diffusion characteristics of neocortex and hippocampus in rat brain slices. We show that D* for calcium is less than the value predicted from the behaviour of the monovalent cation tetramethylammonium (TMA), a commonly used diffusion probe, but D* for calcium increases in both brain regions after the slices are treated with chondroitinase ABC, an enzyme that predominantly cleaves chondroitin sulphate glycans. These results suggest that CSPGs do play a role in determining the local diffusion properties of calcium in brain tissue, most likely through electrostatic interactions mediating rapid equilibrium binding. In contrast, chondroitinase ABC does not affect either the TMA diffusion or the extracellular volume fraction, indicating that the enzyme does not alter the structure of the extracellular space and that the diffusion of small monovalent cations is not affected by CSPGs in the normal brain ionic milieu. Both calcium and CSPGs are known to have many distinct roles in brain physiology, including brain repair, and our study suggests they may be functionally coupled through calcium diffusion properties.
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Affiliation(s)
- Sabina Hrabetová
- Department of Physiology and Neuroscience, NYU School of Medicine, 550 First Avenue, New York, NY 10016, USA
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15
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Baeurle S, Kiselev M, Makarova E, Nogovitsin E. Effect of the counterion behavior on the frictional–compressive properties of chondroitin sulfate solutions. POLYMER 2009. [DOI: 10.1016/j.polymer.2009.01.066] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Nap RJ, Szleifer I. Structure and interactions of aggrecans: statistical thermodynamic approach. Biophys J 2008; 95:4570-83. [PMID: 18689463 PMCID: PMC2576360 DOI: 10.1529/biophysj.108.133801] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2008] [Accepted: 07/29/2008] [Indexed: 11/18/2022] Open
Abstract
Weak polyelectrolytes tethered to cylindrical surfaces are investigated using a molecular theory. These polymers form a model system to describe the properties of aggrecan molecules, which is one of the main components of cartilage. We have studied the structural and thermodynamical properties of two interacting aggrecans with a molecular density functional theory that incorporates the acid-base equilibrium as well as the molecular properties: including conformations, size, shape, and charge distribution of all molecular species. The effect of acidity and salt concentration on the behavior is explored in detail. The repulsive interactions between two cylindrical-shaped aggrecans are strongly influenced by both the salt concentration and the pH. With increasing acidity, the polyelectrolytes of the aggrecan acquire charge and with decreasing salt concentration those charges become less screened. Consequently the interactions increase in size and range with increasing acidity and decreasing salt concentration. The size and range of the forces offers a possible explanation to the aggregation behavior of aggrecans and for their ability to resist compressive forces in cartilage. Likewise, the interdigitation of two aggrecan molecules is strongly affected by the salt concentration as well as the pH. With increasing pH, the number of charges increases, causing the repulsions between the polymers to increase, leading to a lower interdigitation of the two cylindrical polymer layers of the aggrecan molecules. The low interdigitation in charged polyelectrolytes layers provides an explanation for the good lubrication properties of polyelectrolyte layers in general and cartilage in particular.
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Affiliation(s)
- Rikkert J Nap
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, USA
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Abstract
Here it is reported that aggrecan, the highly negatively charged macromolecule in the cartilage extracellular matrix, undergoes Ca(2+)-mediated self-adhesion after static compression even in the presence of strong electrostatic repulsion in physiological-like solution conditions. Aggrecan was chemically end-attached onto gold-coated planar silicon substrates and gold-coated microspherical atomic force microscope probe tips (end radius R approximately 2.5 mum) at a density ( approximately 40 mg/mL) that simulates physiological conditions in the tissue ( approximately 20-80 mg/mL). Colloidal force spectroscopy was employed to measure the adhesion between opposing aggrecan monolayers in NaCl (0.001-1.0 M) and NaCl + CaCl(2) ([Cl(-)] = 0.15 M, [Ca(2+)] = 0 - 75 mM) aqueous electrolyte solutions. Aggrecan self-adhesion was found to increase with increasing surface equilibration time upon compression (0-30 s). Hydrogen bonding and physical entanglements between the chondroitin sulfate-glycosaminoglycan side chains are proposed as important factors contributing to aggrecan self-adhesion. Self-adhesion was found to significantly increase with decreasing bath ionic strength (and hence, electrostatic double-layer repulsion), as well as increasing Ca(2+) concentration due to the additional ion-bridging effects. It is hypothesized that aggrecan self-adhesion, and the macromolecular energy dissipation that results from this self-adhesion, could be important factors contributing to the self-assembled architecture and integrity of the cartilage extracellular matrix in vivo.
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18
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Affiliation(s)
- Barbara Mulloy
- National Institute for Biological Standards and Control, Herts. EN6 3QG, United Kingdom
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