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Rajankunte Mahadeshwara M, Al-Jawad M, Hall RM, Pandit H, El-Gendy R, Bryant M. How Do Cartilage Lubrication Mechanisms Fail in Osteoarthritis? A Comprehensive Review. Bioengineering (Basel) 2024; 11:541. [PMID: 38927777 PMCID: PMC11200606 DOI: 10.3390/bioengineering11060541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 05/02/2024] [Accepted: 05/21/2024] [Indexed: 06/28/2024] Open
Abstract
Cartilage degeneration is a characteristic of osteoarthritis (OA), which is often observed in aging populations. This degeneration is due to the breakdown of articular cartilage (AC) mechanical and tribological properties primarily attributed to lubrication failure. Understanding the reasons behind these failures and identifying potential solutions could have significant economic and societal implications, ultimately enhancing quality of life. This review provides an overview of developments in the field of AC, focusing on its mechanical and tribological properties. The emphasis is on the role of lubrication in degraded AC, offering insights into its structure and function relationship. Further, it explores the fundamental connection between AC mechano-tribological properties and the advancement of its degradation and puts forth recommendations for strategies to boost its lubrication efficiency.
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Affiliation(s)
- Manoj Rajankunte Mahadeshwara
- Institute of Functional Surfaces, Mechanical Engineering, University of Leeds, Leeds LS2 9JT, UK
- Department of Oral Biology, Faculty of Dentistry, University of Leeds, Leeds LS2 9JT, UK; (M.A.-J.); (R.E.-G.)
| | - Maisoon Al-Jawad
- Department of Oral Biology, Faculty of Dentistry, University of Leeds, Leeds LS2 9JT, UK; (M.A.-J.); (R.E.-G.)
| | - Richard M. Hall
- School of Engineering, College of Engineering and Physical Sciences, University of Birmingham, Birmingham B15 2TT, UK;
| | - Hemant Pandit
- Leeds Institute of Rheumatic and Musculoskeletal Medicine (LIRMM), University of Leeds, Chapel Allerton Hospital, Leeds LS7 4SA, UK;
| | - Reem El-Gendy
- Department of Oral Biology, Faculty of Dentistry, University of Leeds, Leeds LS2 9JT, UK; (M.A.-J.); (R.E.-G.)
- Department of Oral Pathology, Faculty of Dentistry, Suez Canal University, Ismailia 3, Ismailia Governorate 8366004, Egypt
| | - Michael Bryant
- Institute of Functional Surfaces, Mechanical Engineering, University of Leeds, Leeds LS2 9JT, UK
- School of Engineering, College of Engineering and Physical Sciences, University of Birmingham, Birmingham B15 2TT, UK;
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2
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Klahr B, Lanzendorf JZ, Thiesen JLM, Pinto OT, Müller LG, Carniel TA, Fancello EA. On the contribution of solid and fluid behavior to the modeling of the time-dependent mechanics of tendons under semi-confined compression. J Mech Behav Biomed Mater 2023; 148:106220. [PMID: 37944227 DOI: 10.1016/j.jmbbm.2023.106220] [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: 05/16/2023] [Revised: 10/10/2023] [Accepted: 10/31/2023] [Indexed: 11/12/2023]
Abstract
The present work aims to investigate whether it is possible to identify and quantify the contributions of the interstitial fluid and the solid skeleton to the overall time-dependent behavior of tendons based on a single mechanical test. For this purpose, the capabilities of three different time-dependent models (a viscoelastic, a poroelastic and a poroviscoelastic) were investigated in the modeling of the experimental behavior obtained from semi-confined compression with stress relaxation tests transverse to collagen fibers. The main achieved result points out that the poroviscoelastic model was the only one capable to characterize both the experimental responses of the force and volume changes of the tissue samples. Moreover, further analysis of this model shows that while the kinematics of the sample are mainly governed by the fluid flow (pore pressure contribution of the model), the behavior intrinsically associated with the viscoelastic solid skeleton makes a significant contribution to the experimental force response. This study reinforces the importance of taking both the experimental kinematics and kinetics of tendon tissues into account during the constitutive characterization procedure.
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Affiliation(s)
- Bruno Klahr
- Department of Mechanical Engineering, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Jonas Zin Lanzendorf
- Department of Mechanical Engineering, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - José Luís Medeiros Thiesen
- Department of Mechanical Engineering, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Otávio Teixeira Pinto
- Department of Mechanical Engineering, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Liz Girardi Müller
- Graduate Program in Environmental Sciences, Community University of Chapecó Region, Chapecó, Santa Catarina, Brazil
| | - Thiago André Carniel
- Graduate Program in Health Sciences, Community University of Chapecó Region, Chapecó, Santa Catarina, Brazil; Polytechnic School, Community University of Chapecó Region, Chapecó, Santa Catarina, Brazil.
| | - Eduardo Alberto Fancello
- Department of Mechanical Engineering, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil; University Hospital, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil
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Carniel TA, Eckert JP, Atuatti EB, Klahr B, Thiesen JLM, Mentges J, Pinto OT, Müller LG, Fancello EA. Is the fluid volume fraction equal to the water content in tendons? Insights on biphasic modeling. J Mech Behav Biomed Mater 2023; 140:105703. [PMID: 36764169 DOI: 10.1016/j.jmbbm.2023.105703] [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: 11/27/2022] [Revised: 01/12/2023] [Accepted: 02/01/2023] [Indexed: 02/09/2023]
Abstract
The mass density of highly hydrated soft tissues is generally assumed to be very close to that of the water, resulting that the fluid mass fraction (water content) being equal to the fluid volume fraction. Within this context, the present study aims to investigate whether such an assumption actually holds for tendon tissues and to what extent it may affect the constitutive characterizations based on biphasic (poroelastic) models. Once the water content was assessed by a classical drying assay, the fluid volume fraction was obtained based on an image segmentation approach. The main achieved results point out that the fluid volume fraction is ∼20% higher than the water content in the studied tendons (flexor digitorum profundus bovine tendons). Based on this, it is shown that the use of the water content instead of the fluid volume fraction may considerably bias the results drawn by biphasic modeling of tendons. Accordingly, a proper measurement of the fluid volume fraction is then required.
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Affiliation(s)
- Thiago André Carniel
- Polytechnic School, Community University of Chapecó Region, Chapecó, SC, Brazil.
| | - João Paulo Eckert
- Polytechnic School, Community University of Chapecó Region, Chapecó, SC, Brazil
| | | | - Bruno Klahr
- Department of Mechanical Engineering, Federal University of Santa Catarina, Florianópolis, SC, Brazil
| | | | - Julia Mentges
- Polytechnic School, Community University of Chapecó Region, Chapecó, SC, Brazil
| | - Otávio Teixeira Pinto
- Department of Mechanical Engineering, Federal University of Santa Catarina, Florianópolis, SC, Brazil
| | - Liz Girardi Müller
- Graduate Program in Environmental Sciences, Community University of Chapecó Region, Chapecó, SC, Brazil
| | - Eduardo Alberto Fancello
- Department of Mechanical Engineering, Federal University of Santa Catarina, Florianópolis, SC, Brazil; University Hospital, Federal University of Santa Catarina, Florianópolis, SC, Brazil
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Belluzzi E, Todros S, Pozzuoli A, Ruggieri P, Carniel EL, Berardo A. Human Cartilage Biomechanics: Experimental and Theoretical Approaches towards the Identification of Mechanical Properties in Healthy and Osteoarthritic Conditions. Processes (Basel) 2023. [DOI: 10.3390/pr11041014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023] Open
Abstract
Articular cartilage is a complex connective tissue with the fundamental functions of load bearing, shock absorption and lubrication in joints. However, traumatic events, aging and degenerative pathologies may affect its structural integrity and function, causing pain and long-term disability. Osteoarthritis represents a health issue, which concerns an increasing number of people worldwide. Moreover, it has been observed that this pathology also affects the mechanical behavior of the articular cartilage. To better understand this correlation, the here proposed review analyzes the physiological aspects that influence cartilage microstructure and biomechanics, with a special focus on the pathological changes caused by osteoarthritis. Particularly, the experimental data on human articular cartilage are presented with reference to different techniques adopted for mechanical testing and the related theoretical mechanical models usually applied to articular cartilage are briefly discussed.
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Sundar S, Linardi R, Gaesser A, Guo T, Ortved K, Engiles J, Parreno J, Dhong C. Optics-Free, In Situ Swelling Monitoring of Articular Cartilage with Graphene Strain Sensors. ACS Biomater Sci Eng 2023; 9:1011-1019. [PMID: 36701648 PMCID: PMC10123914 DOI: 10.1021/acsbiomaterials.2c01456] [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] [Indexed: 01/27/2023]
Abstract
Articular cartilage derives its load-bearing strength from the mechanical and physiochemical coupling between the collagen network and negatively charged proteoglycans, respectively. Current disease modeling approaches and treatment strategies primarily focus on cartilage stiffness, partly because indentation tests are readily accessible. However, stiffness measurements via indentation alone cannot discriminate between proteoglycan degradation versus collagen degradation, and there is a lack of methods to monitor physiochemical contributors in full-stack tissue. To decouple these contributions, here, we developed a platform that measures tissue swelling in full-depth equine cartilage explants using piezoresistive graphene strain sensors. These piezoresistive strain sensors are embedded within an elastomer bulk and have sufficient sensitivity to resolve minute, real-time changes in swelling. By relying on simple DC resistance measurements over optical techniques, our platform can analyze multiple samples in parallel. Using these devices, we found that cartilage explants under enzymatic digestion showed distinctive swelling responses to a hypotonic challenge and established average equilibrium swelling strains in healthy cartilage (4.6%), cartilage with proteoglycan loss (0.5%), and in cartilage with both collagen and proteoglycan loss (-2.6%). Combined with histology, we decoupled the pathologic swelling responses as originating either from reduced fixed charge density or from loss of intrinsic stiffness of the collagen matrix in the superficial zone. By providing scalable and in situ monitoring of cartilage swelling, our platform could facilitate regenerative medicine approaches aimed at restoring osmotic function in osteoarthritic cartilage or could be used to validate physiologically relevant swelling behavior in synthetic hydrogels.
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Affiliation(s)
- Shalini Sundar
- Department of Biomedical Engineering, University of Delaware, Newark, Delaware, USA
| | - Renata Linardi
- Department of Clinical Studies, University of Pennsylvania School of Veterinary Medicine, New Bolton Center, Kennett Square, Pennsylvania, USA
| | - Angela Gaesser
- Department of Clinical Studies, University of Pennsylvania School of Veterinary Medicine, New Bolton Center, Kennett Square, Pennsylvania, USA
| | - Tianzheng Guo
- Department of Materials Science & Engineering, University of Delaware, Newark, Delaware, USA
| | - Kyla Ortved
- Department of Clinical Studies, University of Pennsylvania School of Veterinary Medicine, New Bolton Center, Kennett Square, Pennsylvania, USA
| | - Julie Engiles
- Department of Clinical Studies, University of Pennsylvania School of Veterinary Medicine, New Bolton Center, Kennett Square, Pennsylvania, USA
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, USA
| | - Justin Parreno
- Department of Biomedical Engineering, University of Delaware, Newark, Delaware, USA
- Department of Biological Sciences, University of Delaware, Newark, Delaware, USA
| | - Charles Dhong
- Department of Biomedical Engineering, University of Delaware, Newark, Delaware, USA
- Department of Materials Science & Engineering, University of Delaware, Newark, Delaware, USA
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Warren MR, Bajpayee AG. Modeling Electrostatic Charge Shielding Induced by Cationic Drug Carriers in Articular Cartilage Using Donnan Osmotic Theory. Bioelectricity 2022; 4:248-258. [PMID: 36644714 PMCID: PMC9811830 DOI: 10.1089/bioe.2021.0026] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Background Positively charged drug carriers are rapidly emerging as a viable solution for long-standing challenges in delivery to dense, avascular, negatively charged tissues. These cationic carriers have demonstrated especially strong promise in targeting drugs to articular cartilage for osteoarthritis (OA) treatment. It is critical to evaluate the dose-dependent effects of their high intratissue uptake levels on charge-shielding of anionic matrix constituents, and the resulting changes in tissue osmotic swelling and mechanical integrity. Materials and Methods We use the ideal Donnan osmotic theory to derive a model for predicting intracartilage swelling pressures as a function of net charge (z) and equilibrium uptake of short-length, arginine-rich, multivalent, cationic peptide carriers (cationic peptide carriers [CPCs], z varied from +8 to +20) in cartilage samples with varying arthritic severities and fixed charge density (FCD). We use this model to determine the dose-dependent influence of CPCs on both physiological osmotic swelling pressures and compressive electrostatic moduli of cartilage in healthy and arthritic states. Results Under physiological conditions, the Donnan model predicted carrier-induced reductions in free swelling pressure between 8 and 29 kPa, and diminished compressive modulus by 20-68 kPa, both dependent on the net charge and uptake of CPCs. The magnitudes of deswelling and stiffness reduction increased monotonically with carrier uptake and net charge. Furthermore, predicted levels of deswelling by CPC charge shielding were amplified in tissues with reduced FCD (which model OA). Finally, the Donnan model predicted markedly higher reductions in tissue compressive modulus in hypotonic bathing salinity compared with physiological and hypertonic conditions. Conclusion This analysis demonstrates the importance of considering charge shielding as a likely adverse effect associated with uptake of cationic drug carriers into negatively charged tissues, especially in the case of damaged tissue. The simple modeling approach and principles described herein can inform the design of cationic drug delivery carriers and their clinical treatment regimens.
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Affiliation(s)
- Matthew R. Warren
- Department of Bioengineering and Northeastern University, Boston, Massachusetts, USA
| | - Ambika G. Bajpayee
- Department of Bioengineering and Northeastern University, Boston, Massachusetts, USA
- Department of Mechanical Engineering, Northeastern University, Boston, Massachusetts, USA
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7
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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.
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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.
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8
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Cuffaro D, Ciccone L, Rossello A, Nuti E, Santamaria S. Targeting Aggrecanases for Osteoarthritis Therapy: From Zinc Chelation to Exosite Inhibition. J Med Chem 2022; 65:13505-13532. [PMID: 36250680 PMCID: PMC9620172 DOI: 10.1021/acs.jmedchem.2c01177] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Indexed: 11/30/2022]
Abstract
Osteoarthritis (OA) is the most common degenerative joint disease. In 1999, two members of the A Disintegrin and Metalloproteinase with Thrombospondin Motifs (ADAMTS) family of metalloproteinases, ADAMTS4 and ADAMTS5, or aggrecanases, were identified as the enzymes responsible for aggrecan degradation in cartilage. The first aggrecanase inhibitors targeted the active site by chelation of the catalytic zinc ion. Due to the generally disappointing performance of zinc-chelating inhibitors in preclinical and clinical studies, inhibition strategies tried to move away from the active-site zinc in order to improve selectivity. Exosite inhibitors bind to proteoglycan-binding residues present on the aggrecanase ancillary domains (called exosites). While exosite inhibitors are generally more selective than zinc-chelating inhibitors, they are still far from fulfilling their potential, partly due to a lack of structural and functional data on aggrecanase exosites. Filling this gap will inform the design of novel potent, selective aggrecanase inhibitors.
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Affiliation(s)
- Doretta Cuffaro
- Department
of Pharmacy, University of Pisa, via Bonanno 6, 56126 Pisa, Italy
| | - Lidia Ciccone
- Department
of Pharmacy, University of Pisa, via Bonanno 6, 56126 Pisa, Italy
| | - Armando Rossello
- Department
of Pharmacy, University of Pisa, via Bonanno 6, 56126 Pisa, Italy
| | - Elisa Nuti
- Department
of Pharmacy, University of Pisa, via Bonanno 6, 56126 Pisa, Italy
| | - Salvatore Santamaria
- Department
of Immunology and Inflammation, Imperial
College London, Du Cane Road, London W12
0NN, U.K.
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9
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Warren MR, Vedadghavami A, Bhagavatula S, Bajpayee AG. Effects of polycationic drug carriers on the electromechanical and swelling properties of cartilage. Biophys J 2022; 121:3542-3561. [PMID: 35765244 PMCID: PMC9515003 DOI: 10.1016/j.bpj.2022.06.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 06/07/2022] [Accepted: 06/23/2022] [Indexed: 11/15/2022] Open
Abstract
Cationic nanocarriers offer a promising solution to challenges in delivering drugs to negatively charged connective tissues, such as to articular cartilage for the treatment of osteoarthritis (OA). However, little is known about the effects that cationic macromolecules may have on the mechanical properties of cartilage at high interstitial concentrations. We utilized arginine-rich cationic peptide carriers (CPCs) with varying net charge (from +8 to +20) to investigate the biophysical mechanisms of nanocarrier-induced alterations to cartilage biomechanical properties. We observed that CPCs increased the compressive modulus of healthy bovine cartilage explants by up to 70% and decreased the stiffness of glycosaminoglycan-depleted tissues (modeling OA) by 69%; in both cases, the magnitude of the change in stiffness correlated with the uptake of CPC charge variants. Next, we directly measured CPC-induced osmotic deswelling in cartilage tissue due to shielding of charge repulsions between anionic extracellular matrix constituents, with magnitudes of reductions between 36 and 64 kPa. We then demonstrated that electrostatic interactions were required for CPC-induced stiffening to occur, evidenced by no observed increase in tissue stiffness when measured in hypertonic bathing salinity. We applied a non-ideal Donnan osmotic model (under triphasic theory) to separate bulk modulus measurements into Donnan and non-Donnan components, which further demonstrated the conflicting charge-shielding and matrix-stiffening effects of CPCs. These results show that cationic drug carriers can alter tissue mechanical properties via multiple mechanisms, including the expected charge shielding as well as a novel stiffening phenomenon mediated by physical linkages. We introduce a model for how the magnitudes of these mechanical changes depend on tunable physical properties of the drug carrier, including net charge, size, and spatial charge distribution. We envision that the results and theory presented herein will inform the design of future cationic drug-delivery systems intended to treat diseases in a wide range of connective tissues.
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Affiliation(s)
- Matthew R Warren
- Department of Bioengineering, Northeastern University, Boston, Massachusetts
| | - Armin Vedadghavami
- Department of Bioengineering, Northeastern University, Boston, Massachusetts
| | - Sanjana Bhagavatula
- Department of Bioengineering, Northeastern University, Boston, Massachusetts
| | - Ambika G Bajpayee
- Department of Bioengineering, Northeastern University, Boston, Massachusetts; Department of Mechanical Engineering, Northeastern University, Boston, Massachusetts.
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10
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Krull CM, Rife J, Klamer B, Purmessur D, Walter BA. Pericellular heparan sulfate proteoglycans: Role in regulating the biosynthetic response of nucleus pulposus cells to osmotic loading. JOR Spine 2022; 5:e1209. [PMID: 35783912 PMCID: PMC9238280 DOI: 10.1002/jsp2.1209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 04/26/2022] [Accepted: 05/12/2022] [Indexed: 12/04/2022] Open
Abstract
Background Daily physiologic loading causes fluctuations in hydration of the intervertebral disc (IVD); thus, the embedded cells experience cyclic alterations to their osmotic environment. These osmotic fluctuations have been described as a mechanism linking mechanics and biology, and have previously been shown to promote biosynthesis in chondrocytes. However, this phenomenon has yet to be fully interrogated in the IVD. Additionally, the specialized extracellular matrix surrounding the cells, the pericellular matrix (PCM), transduces the biophysical signals that cells ultimately experience. While it is known that the PCM is altered in disc degeneration, whether it disrupts normal osmotic mechanotransduction has yet to be determined. Thus, our objectives were to assess: (1) whether dynamic osmotic conditions stimulate biosynthesis in nucleus pulposus cells, and (2) whether pericellular heparan sulfate proteoglycans (HSPGs) modulate the biosynthetic response to osmotic loading. Methods Bovine nucleus pulposus cells isolated with retained PCM were encapsulated in 1.5% alginate beads and treated with or without heparinase III, an enzyme that degrades the pericellular HSPGs. Beads were subjected to 1 h of daily iso-osmotic, hyper-osmotic, or hypo-osmotic loading for 1, 2, or 4 weeks. At each timepoint the total amount of extracellular and pericellular sGAG/DNA were quantified. Additionally, whether osmotic loading triggered alterations to HSPG sulfation was assessed via immunohistochemistry for the heparan sulfate 6-O-sulfertransferase 1 (HS6ST1) enzyme. Results Osmotic loading significantly influenced sGAG/DNA accumulation with a hyper-osmotic change promoting the greatest sGAG/DNA accumulation in the pericellular region compared with iso-osmotic conditions. Heparanase-III treatment significantly reduced extracellular sGAG/DNA but pericellular sGAG was not affected. HS6ST1 expression was not affected by osmotic loading. Conclusion Results suggest that hyper-osmotic loading promotes matrix synthesis and that modifications to HSPGs directly influence the metabolic responses of cells to osmotic fluctuations. Collectively, results suggest degeneration-associated modifications to pericellular HSPGs may contribute to the altered mechanobiology observed in disease.
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Affiliation(s)
- Carly M. Krull
- Department of Biomedical EngineeringThe Ohio State UniversityColumbusOhioUSA
| | - Jordan Rife
- Department of Biomedical EngineeringThe Ohio State UniversityColumbusOhioUSA
| | - Brett Klamer
- Department of Biomedical Informatics, Center for BiostatisticsThe Ohio State UniversityColumbusOhioUSA
| | - Devina Purmessur
- Department of Biomedical EngineeringThe Ohio State UniversityColumbusOhioUSA
- Department of OrthopedicsThe Ohio State University Wexner Medical CenterColumbusOhioUSA
- Spine Research InstituteThe Ohio State UniversityColumbusOhioUSA
| | - Benjamin A. Walter
- Department of Biomedical EngineeringThe Ohio State UniversityColumbusOhioUSA
- Department of OrthopedicsThe Ohio State University Wexner Medical CenterColumbusOhioUSA
- Spine Research InstituteThe Ohio State UniversityColumbusOhioUSA
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11
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Nedrelow DS, Damodaran KV, Thurston TA, Beyer JP, Barocas VH. Residual stress and osmotic swelling of the periodontal ligament. Biomech Model Mechanobiol 2021; 20:2047-2059. [PMID: 34365539 DOI: 10.1007/s10237-021-01493-x] [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: 01/07/2021] [Accepted: 07/09/2021] [Indexed: 11/28/2022]
Abstract
Osmotic swelling and residual stress are increasingly recognized as important factors in soft tissue biomechanics. Little attention has been given to residual stress in periodontal ligament (PDL) biomechanics despite its rapid growth and remodeling potential. Those tissues that bear compressive loads, e.g., articular cartilage, intervertebral disk, have received much attention related to their capacities for osmotic swelling. To understand residual stress and osmotic swelling in the PDL, it must be asked (1) to what extent, if any, does the PDL exhibit residual stress and osmotic swelling, and (2) if so, whether residual stress and osmotic swelling are mechanically significant to the PDL's stress/strain behavior under external loading. Here, we incrementally built a series of computer models that were fit to uniaxial loading, osmotic swelling and residual stretch data. The models were validated with in vitro shear tests and in vivo tooth-tipping data. Residual stress and osmotic swelling models were used to analyze tension and compression stress (principal stress) effects in PDL specimens under external loads. Shear-to-failure experiments under osmotic conditions were performed and modeled to determine differences in mechanics and failure of swollen periodontal ligament. Significantly higher failure shear stresses in swollen PDL suggested that osmotic swelling reduced tension and thus had a strengthening effect. The in vivo model's first and third principal stresses were both higher with residual stress and osmotic swelling, but smooth stress gradients prevailed throughout the three-dimensional PDL anatomy. The addition of PDL stresses from residual stress and osmotic swelling represents a unique concept in dental biomechanics.
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Affiliation(s)
- David S Nedrelow
- Department of Biomedical Engineering, University of Minnesota-Twin Cities, Minneapolis, USA.
| | - Kishore V Damodaran
- Department of Developmental and Surgical Sciences, University of Minnesota School of Dentistry, Minneapolis, USA
| | - Theresa A Thurston
- Department of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, USA
| | - John P Beyer
- Department of Developmental and Surgical Sciences, University of Minnesota School of Dentistry, Minneapolis, USA
| | - Victor H Barocas
- Department of Biomedical Engineering, University of Minnesota-Twin Cities, Minneapolis, USA
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