1
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Iwasaki N, Roldo M, Karali A, Blunn G. In vitro development of a muscle-tendon junction construct using decellularised extracellular matrix: Effect of cyclic tensile loading. Biomater Adv 2024; 161:213873. [PMID: 38692180 DOI: 10.1016/j.bioadv.2024.213873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 04/10/2024] [Accepted: 04/24/2024] [Indexed: 05/03/2024]
Abstract
The muscle tendon junction (MTJ) plays a crucial role in transmitting the force generated by muscles to the tendon and then to the bone. Injuries such as tears and strains frequently happen at the MTJ, where the regenerative process is limited due to poor vascularization and the complex structure of the tissue. Current solutions for a complete tear at the MTJ have not been successful and therefore, the development of a tissue-engineered MTJ may provide a more effective treatment. In this study, decellularised extracellular matrix (DECM) derived from sheep MTJ was used to provide a scaffold for the MTJ with the relevant mechanical properties and differentiation cues such as the relase of growth factors. Human mesenchymal stem cells (MSCs) were seeded on DECM and 10 % cyclic strain was applied using a bioreactor. MSCs cultured on DECM showed significantly higher gene and protein expression of MTJ markers such as collagen 22, paxillin and talin, than MSCs in 2D culture. Although collagen 22 protein expression was higher in the cells with strain than without strain, reduced gene expression of other MTJ markers was observed when the strain was applied. DECM combined with 10 % strain enhanced myogenic differentiation, while tenogenic differentiation was reduced when compared to static cultures of MSCs on DECM. For the first time, these results showed that DECM derived from the MTJ can induce MTJ marker gene and protein expression by MSCs, however, the effect of strain on the MTJ development in DECM culture needs further investigation.
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Affiliation(s)
- Nodoka Iwasaki
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, UK.
| | - Marta Roldo
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, UK
| | - Aikaterina Karali
- School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth, UK
| | - Gordon Blunn
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, UK
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Davis S, Karali A, Balcaen T, Zekonyte J, Pétré M, Roldo M, Kerckhofs G, Blunn G. Comparison of two contrast-enhancing staining agents for use in X-ray imaging and digital volume correlation measurements across the cartilage-bone interface. J Mech Behav Biomed Mater 2024; 152:106414. [PMID: 38277908 DOI: 10.1016/j.jmbbm.2024.106414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 12/11/2023] [Accepted: 01/19/2024] [Indexed: 01/28/2024]
Abstract
OBJECTIVE The pathogenesis of osteoarthritis (OA) is associated with subchondral bone changes, which is linked to abnormal strain distribution in the overlying articular cartilage. This highlights the importance of understanding mechanical interaction at the cartilage-bone interface. The aim of this study is to compare solutions of two contrast-enhancing staining agents (CESA) for combining high-resolution Contrast-Enhanced X-ray microfocus Computed Tomography (CECT) with Digital Volume Correlation (DVC) for full-field strain measurements at the cartilage-bone interface. DESIGN Bovine osteochondral plugs were stained with phosphotungstic acid (PTA) in 70% ethanol or 1:2 hafnium-substituted Wells-Dawson polyoxometalate (Hf-WD POM) in PBS. Mechanical properties were assessed using micromechanical probing and nanoindentation. Strain uncertainties (from CECT data) were evaluated following two consecutive unloaded scans. Residual strains were computed following unconfined compression (ex situ) testing. RESULTS PTA and Hf-WD POM enabled the visualisation of structural features in cartilage, allowing DVC computation on the CECT data. Residual strains up to ∼10,000 μɛ were detected up to the tidemark. Nanoindentation showed that PTA-staining caused an average ∼6-fold increase in articular cartilage stiffness, a ∼19-fold increase in reduced modulus and ∼7-fold increase in hardness, whereas Hf-WD POM-stained specimens had mechanical properties similar to pre-stain tissue. Micromechanical probing showed a 77% increase in cartilage surface stiffness after PTA-staining, in comparison to a 16% increase in stiffness after staining with Hf-WD POM. CONCLUSION Hf-WD POM is a more suitable CESA solution compared to PTA for CECT imaging combined with DVC as it allowed visualisation of structural features in the cartilage tissue whilst more closely maintaining tissue mechanical properties.
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Affiliation(s)
- Sarah Davis
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, PO1 2DT, UK; School of Mechanical and Design Engineering, University of Portsmouth, PO1 3DJ, UK.
| | - Aikaterina Karali
- School of Mechanical and Design Engineering, University of Portsmouth, PO1 3DJ, UK
| | - Tim Balcaen
- Biomechanics Lab, Institute of Mechanics, Materials and Civil Engineering, UCLouvain, Louvain-la-Neuve, Belgium; Pole of Morphology, Institute of Experimental and Clinical Research, UCLouvain, Brussels, Belgium; Molecular Design and Synthesis, Department of Chemistry, KU Leuven, Leuven, Belgium
| | - Jurgita Zekonyte
- School of Mechanical and Design Engineering, University of Portsmouth, PO1 3DJ, UK
| | - Maïté Pétré
- Biomechanics Lab, Institute of Mechanics, Materials and Civil Engineering, UCLouvain, Louvain-la-Neuve, Belgium; Pole of Morphology, Institute of Experimental and Clinical Research, UCLouvain, Brussels, Belgium; Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Heverlee, Belgium
| | - Marta Roldo
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, PO1 2DT, UK
| | - Greet Kerckhofs
- Biomechanics Lab, Institute of Mechanics, Materials and Civil Engineering, UCLouvain, Louvain-la-Neuve, Belgium; Pole of Morphology, Institute of Experimental and Clinical Research, UCLouvain, Brussels, Belgium; Department of Materials Engineering, KU Leuven, Heverlee, Belgium; Prometheus, Division for Skeletal Tissue Engineering, KU Leuven, Leuven, Belgium
| | - Gordon Blunn
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, PO1 2DT, UK
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Yavuzyegit B, Karali A, De Mori A, Smith N, Usov S, Shashkov P, Bonithon R, Blunn G. Evaluation of Corrosion Performance of AZ31 Mg Alloy in Physiological and Highly Corrosive Solutions. ACS Appl Bio Mater 2024; 7:1735-1747. [PMID: 38411089 PMCID: PMC10952013 DOI: 10.1021/acsabm.3c01169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Revised: 02/11/2024] [Accepted: 02/13/2024] [Indexed: 02/28/2024]
Abstract
Resorbable Mg and Mg alloys have gained significant interest as promising biomedical materials. However, corrosion of these alloys can lead to premature reduction in their mechanical properties, and therefore their corrosion rate needs to be controlled. The aim of this study is to select an appropriate environment where the effects of coatings on the corrosion rate of the underlying Mg alloy can be discerned and measured in a relatively short time period. The corrosion resistance of uncoated AZ31 alloy in different solutions [Hank's Balanced Salt Solution, 1× phosphate buffered solution (PBS), 4× PBS, 0.9%, 3.5%, and 5 M sodium chloride (NaCl)] was determined by measuring the weight loss over a 2 week period. Upon exposure to physiological solutions, the uncoated AZ31 alloys exhibited a variable weight increase of 0.4 ± 0.4%. 3.5% and 5 M NaCl solutions led to 0.27 and 9.7 mm/year corrosion rates, respectively, where the compositions of corrosion products from AZ31 in all saline solutions were similar. However, the corrosion of the AZ31 alloy when coated by electrochemical oxidation with two phosphate coatings, one containing fluorine (PF) and another containing both fluorine and silica (PFS), showed 0.3 and 0.25 mm/year corrosion rates, respectively. This is more than 30 times lower than that of the uncoated alloy (7.8 mm/year), making them promising candidates for corrosion protection in severe corrosive environments. Cross-sections of the samples showed that the coatings protected the alloy from corrosion by preventing access of saline to the alloy surface, and this was further reinforced by corrosion products from both the alloy and the coatings forming an additional barrier. The information in this paper provides a methodology for evaluating the effects of coatings on the rate of corrosion of magnesium alloys.
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Affiliation(s)
- Berzah Yavuzyegit
- School
of Pharmacy and Biomedical Sciences, Faculty of Science and Health, University of Portsmouth, St Michael’s Building, White Swan Road, Portsmouth PO1 2DT, U.K.
- Mechanical
Engineering Department, Recep Tayyip Erdogan
University, Rize 53100, Turkey
| | - Aikaterina Karali
- School
of Mechanical & Design Engineering Faculty of Technology, University of Portsmouth, Anglesea Building, Anglesea Road, Portsmouth PO1 3DJ, U.K.
| | - Arianna De Mori
- School
of Pharmacy and Biomedical Sciences, Faculty of Science and Health, University of Portsmouth, St Michael’s Building, White Swan Road, Portsmouth PO1 2DT, U.K.
| | - Nigel Smith
- BioCera
Medical Limited, 3b Homefield
Road, Haverhill CB9 8QP, Suffolk, U.K.
| | - Sergey Usov
- BioCera
Medical Limited, 3b Homefield
Road, Haverhill CB9 8QP, Suffolk, U.K.
| | - Pavel Shashkov
- BioCera
Medical Limited, 3b Homefield
Road, Haverhill CB9 8QP, Suffolk, U.K.
| | - Roxane Bonithon
- School
of Mechanical & Design Engineering Faculty of Technology, University of Portsmouth, Anglesea Building, Anglesea Road, Portsmouth PO1 3DJ, U.K.
| | - Gordon Blunn
- School
of Pharmacy and Biomedical Sciences, Faculty of Science and Health, University of Portsmouth, St Michael’s Building, White Swan Road, Portsmouth PO1 2DT, U.K.
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Iwasaki N, Karali A, Roldo M, Blunn G. Full-Field Strain Measurements of the Muscle-Tendon Junction Using X-ray Computed Tomography and Digital Volume Correlation. Bioengineering (Basel) 2024; 11:162. [PMID: 38391648 PMCID: PMC10886230 DOI: 10.3390/bioengineering11020162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 02/01/2024] [Indexed: 02/24/2024] Open
Abstract
We report, for the first time, the full-field 3D strain distribution of the muscle-tendon junction (MTJ). Understanding the strain distribution at the junction is crucial for the treatment of injuries and to predict tear formation at this location. Three-dimensional full-field strain distribution of mouse MTJ was measured using X-ray computer tomography (XCT) combined with digital volume correlation (DVC) with the aim of understanding the mechanical behavior of the junction under tensile loading. The interface between the Achilles tendon and the gastrocnemius muscle was harvested from adult mice and stained using 1% phosphotungstic acid in 70% ethanol. In situ XCT combined with DVC was used to image and compute strain distribution at the MTJ under a tensile load (2.4 N). High strain measuring 120,000 µε, 160,000 µε, and 120,000 µε for the first principal stain (εp1), shear strain (γ), and von Mises strain (εVM), respectively, was measured at the MTJ and these values reduced into the body of the muscle or into the tendon. Strain is concentrated at the MTJ, which is at risk of being damaged in activities associated with excessive physical activity.
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Affiliation(s)
- Nodoka Iwasaki
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DT, UK
| | - Aikaterina Karali
- School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth PO1 3DJ, UK
| | - Marta Roldo
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DT, UK
| | - Gordon Blunn
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DT, UK
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De Mori A, Karali A, Daskalakis E, Hing R, Da Silva Bartolo PJ, Cooper G, Blunn G. Poly-ε-Caprolactone 3D-Printed Porous Scaffold in a Femoral Condyle Defect Model Induces Early Osteo-Regeneration. Polymers (Basel) 2023; 16:66. [PMID: 38201731 PMCID: PMC10780383 DOI: 10.3390/polym16010066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 12/17/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024] Open
Abstract
Large bone reconstruction following trauma poses significant challenges for reconstructive surgeons, leading to a healthcare burden for health systems, long-term pain for patients, and complex disorders such as infections that are difficult to resolve. The use of bone substitutes is suboptimal for substantial bone loss, as they induce localized atrophy and are generally weak, and unable to support load. A combination of strong polycaprolactone (PCL)-based scaffolds, with an average channel size of 330 µm, enriched with 20% w/w of hydroxyapatite (HA), β-tricalcium phosphate (TCP), or Bioglass 45S5 (Bioglass), has been developed and tested for bone regeneration in a critical-size ovine femoral condyle defect model. After 6 weeks, tissue ingrowth was analyzed using X-ray computed tomography (XCT), Backscattered Electron Microscopy (BSE), and histomorphometry. At this point, all materials promoted new bone formation. Histological analysis showed no statistical difference among the different biomaterials (p > 0.05), but PCL-Bioglass scaffolds enhanced bone formation in the center of the scaffold more than the other types of materials. These materials show potential to promote bone regeneration in critical-sized defects on load-bearing sites.
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Affiliation(s)
- Arianna De Mori
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, St. Michael’s Building, White Swan Road, Portsmouth PO1 2DT, UK
| | - Aikaterina Karali
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth PO1 3DJ, UK
| | - Evangelos Daskalakis
- School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Manchester M13 9PL, UK (G.C.)
| | - Richard Hing
- School of Earth and Environmental Sciences, University of Portsmouth, Portsmouth PO1 2HB, UK
| | | | - Glen Cooper
- School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Manchester M13 9PL, UK (G.C.)
| | - Gordon Blunn
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, St. Michael’s Building, White Swan Road, Portsmouth PO1 2DT, UK
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6
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Davis S, Zekonyte J, Karali A, Roldo M, Blunn G. Early Degenerative Changes in a Spontaneous Osteoarthritis Model Assessed by Nanoindentation. Bioengineering (Basel) 2023; 10:995. [PMID: 37760097 PMCID: PMC10525236 DOI: 10.3390/bioengineering10090995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 08/15/2023] [Accepted: 08/18/2023] [Indexed: 09/29/2023] Open
Abstract
Understanding early mechanical changes in articular cartilage (AC) and subchondral bone (SB) is crucial for improved treatment of osteoarthritis (OA). The aim of this study was to develop a method for nanoindentation of fresh, unfixed osteochondral tissue to assess the early changes in the mechanical properties of AC and SB. Nanoindentation was performed throughout the depth of AC and SB in the proximal tibia of Dunkin Hartley guinea pigs at 2 months, 3 months, and 2 years of age. The contralateral tibias were either histologically graded for OA or analyzed using immunohistochemistry. The results showed an increase in the reduced modulus (Er) in the deep zone of AC during early-stage OA (6.0 ± 1.75 MPa) compared to values at 2 months (4.04 ± 1.25 MPa) (*** p < 0.001). In severe OA (2-year) specimens, there was a significant reduction in Er throughout the superficial and middle AC zones, which correlated to increased ADAMTS 4 and 5 staining, and proteoglycan loss in these regions. In the subchondral bone, a 35.0% reduction in stiffness was observed between 2-month and 3-month specimens (*** p < 0.001). The severe OA age group had significantly increased SB stiffness of 36.2% and 109.6% compared to 2-month and 3-month-old specimens respectively (*** p < 0.001). In conclusion, this study provides useful information about the changes in the mechanical properties of both AC and SB during both early- and late-stage OA and indicates that an initial reduction in stiffness of the SB and an increase in stiffness in the deep zone of AC may precede early-stage cartilage degeneration.
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Affiliation(s)
- Sarah Davis
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth PO1 2DT, UK; (M.R.); (G.B.)
- School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth PO1 3DJ, UK; (J.Z.); (A.K.)
| | - Jurgita Zekonyte
- School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth PO1 3DJ, UK; (J.Z.); (A.K.)
| | - Aikaterina Karali
- School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth PO1 3DJ, UK; (J.Z.); (A.K.)
| | - Marta Roldo
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth PO1 2DT, UK; (M.R.); (G.B.)
| | - Gordon Blunn
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth PO1 2DT, UK; (M.R.); (G.B.)
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7
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Davis S, Karali A, Zekonyte J, Roldo M, Blunn G. Development of a method to investigate strain distribution across the cartilage-bone interface in guinea pig model of spontaneous osteoarthritis using lab-based contrast enhanced X-ray-computed tomography and digital volume correlation. J Mech Behav Biomed Mater 2023; 144:105999. [PMID: 37406483 DOI: 10.1016/j.jmbbm.2023.105999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 05/23/2023] [Accepted: 06/28/2023] [Indexed: 07/07/2023]
Abstract
OBJECTIVE Strain changes at the cartilage-bone interface play a crucial role in osteoarthritis (OA) development. Contrast-Enhanced X-ray Computed Tomography (CECT) and Digital Volume Correlation (DVC) can measure 3D strain changes at the osteochondral interface. Using lab-based CT systems it is often difficult to visualise soft tissues such as articular cartilage without staining to enhance contrast. Contrast-Enhancing Staining Agents (CESAs), such as Phosphotungstic Acid (PTA) in 70% ethanol, can cause tissue shrinkage and alter tissue mechanics. The aims of this study were, firstly, to assess changes to the mechanical properties of osteochondral tissue after staining with a PTA/PBS solution, and secondly, to visualise articular cartilage during loading and with CECT imaging in order to compare strain across the interface in both healthy and OA joints using DVC. DESIGN Nanoindentation was used to assess changes to mechanical properties in articular cartilage and subchondral bone before and after staining. Hindlimbs from Dunkin-Hartley guinea pigs were stained with 1% PTA/PBS at room temperature for 6 days. Two consecutive CECT datasets were acquired for DVC error analysis. In-situ compression with a load corresponding to 2x body weight was applied, the specimen was re-imaged, and DVC was performed between the pre- and post-load tomograms. RESULTS Nanoindentation before and after PTA/PBS staining showed similar cartilage stiffness (p < 0.05), however, staining significantly decreased the stiffness of subchondral bone (∼9-fold; p = 0.0012). In severe OA specimens, third principal/compressive (εp3) strain was 141.7% higher and shear strain (γ) was 98.2% higher in tibial articular cartilage compared to non-OA (2 - month) specimens. A 23.1% increase in third principal stain strain and a 54.5% significant increase in the shear (γ) strain (p = 0.0027) was transferred into the mineralised regions of calcified cartilage and subchondral bone in severe OA specimens. CONCLUSIONS These results indicate the suitability of PTA in PBS as a contrast agent for the visualisation of cartilage during CECT imaging and allowed DVC computation of strain across the cartilage-bone interface. However, further research is needed to address the reduction in stiffness of subchondral bone after incubation in PBS.
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Affiliation(s)
- Sarah Davis
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, PO1 2DT, UK; School of Mechanical and Design Engineering, University of Portsmouth, PO1 3DJ, UK.
| | - Aikaterina Karali
- School of Mechanical and Design Engineering, University of Portsmouth, PO1 3DJ, UK
| | - Jurgita Zekonyte
- School of Mechanical and Design Engineering, University of Portsmouth, PO1 3DJ, UK
| | - Marta Roldo
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, PO1 2DT, UK
| | - Gordon Blunn
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, PO1 2DT, UK
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8
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Karali A, Dall'Ara E, Zekonyte J, Kao AP, Blunn G, Tozzi G. Effect of radiation-induced damage of trabecular bone tissue evaluated using indentation and digital volume correlation. J Mech Behav Biomed Mater 2023; 138:105636. [PMID: 36608532 DOI: 10.1016/j.jmbbm.2022.105636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 12/09/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022]
Abstract
Exposure to X-ray radiation for an extended amount of time can cause damage to the bone tissue and therefore affect its mechanical properties. Specifically, high-resolution X-ray Computed Tomography (XCT), in both synchrotron and lab-based systems, has been employed extensively for evaluating bone micro-to-nano architecture. However, to date, it is still unclear how long exposures to X-ray radiation affect the mechanical properties of trabecular bone, particularly in relation to lab-XCT systems. Indentation has been widely used to identify local mechanical properties such as hardness and elastic modulus of bone and other biological tissues. The purpose of this study is therefore, to use indentation and XCT-based investigative tools such as digital volume correlation (DVC) to assess the microdamage induced by long exposure of trabecular bone tissue to X-ray radiation and how this affects its local mechanical properties. Trabecular bone specimens were indented before and after X-ray exposures of 33 and 66 h, where variation of elastic modulus was evaluated at every stage. The resulting elastic modulus was decreased, and micro-cracks appeared in the specimens after the first long X-ray exposure and crack formation increased after the second exposure. High strain concentration around the damaged tissue exceeding 1% was also observed from DVC analysis. The outcomes of this study show the importance of designing appropriate XCT-based experiments in lab systems to avoid degradation of the bone tissue mechanical properties due to radiation and these results will help to inform future studies that require long X-ray exposure for in situ experiments or generation of reliable subject-specific computational models.
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Affiliation(s)
- Aikaterina Karali
- School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth, UK.
| | - Enrico Dall'Ara
- Departement of Oncology and Metabolism and Insigneo Institute for in Silico Medicine, University of Sheffield, Sheffield, UK
| | - Jurgita Zekonyte
- School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth, UK
| | - Alexander P Kao
- School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth, UK
| | - Gordon Blunn
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, UK
| | - Gianluca Tozzi
- School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth, UK
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9
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Hexter AT, Karali A, Kao A, Tozzi G, Heidari N, Petrie A, Boyd A, Kalaskar DM, Pendegrass C, Rodeo S, Haddad F, Blunn G. Effect of Demineralized Bone Matrix, Bone Marrow Mesenchymal Stromal Cells, and Platelet-Rich Plasma on Bone Tunnel Healing After Anterior Cruciate Ligament Reconstruction: A Comparative Micro-Computed Tomography Study in a Tendon Allograft Sheep Model. Orthop J Sports Med 2021; 9:23259671211034166. [PMID: 34568508 PMCID: PMC8461134 DOI: 10.1177/23259671211034166] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 04/29/2021] [Indexed: 12/02/2022] Open
Abstract
Background: The effect of demineralized bone matrix (DBM), bone marrow–derived mesenchymal stromal cells (BMSCs), and platelet-rich plasma (PRP) on bone tunnel healing in anterior cruciate ligament reconstruction (ACLR) has not been comparatively assessed. Hypothesis: These orthobiologics would reduce tunnel widening, and the effects on tunnel diameter would be correlated with tunnel wall sclerosis. Study Design: Controlled laboratory study. Methods: A total of 20 sheep underwent unilateral ACLR using tendon allograft and outside-in interference screw fixation. The animals were randomized into 4 groups (n = 5 per group): Group 1 received 4mL of DBM paste, group 2 received 10 million BMSCs in fibrin sealant, group 3 received 12 mL of activated leukocyte-poor platelet-rich plasma, and group 4 (control) received no treatment. The sheep were euthanized after 12 weeks, and micro-computed tomography scans were performed. The femoral and tibial tunnels were divided into thirds (aperture, midportion, and exit), and the trabecular bone structure, bone mineral density (BMD), and tunnel diameter were measured. Tunnel sclerosis was defined by a higher bone volume in a 250-µm volume of interest compared with a 4-mm volume of interest surrounding the tunnel. Results: Compared with the controls, the DBM group had a significantly higher bone volume fraction (bone volume/total volume [BV/TV]) (52.7% vs 31.8%; P = .020) and BMD (0.55 vs 0.47 g/cm3; P = .008) at the femoral aperture and significantly higher BV/TV at femoral midportion (44.2% vs 32.9%; P = .038). There were no significant differences between the PRP and BMSC groups versus controls in terms of trabecular bone analysis or BMD. In the controls, widening at the femoral tunnel aperture was significantly greater than at the midportion (46.7 vs 41.7 mm2; P = .034). Sclerosis of the tunnel was common and most often seen at the femoral aperture. In the midportion of the femoral tunnel, BV/TV (r = 0.52; P = .019) and trabecular number (rS = 0.50; P = .024) were positively correlated with tunnel widening. Conclusion: Only DBM led to a significant increase in bone volume, which was seen in the femoral tunnel aperture and midportion. No treatment significantly reduced bone tunnel widening. Tunnel sclerosis in the femoral tunnel midportion was correlated significantly with tunnel widening. Clinical Relevance: DBM might have potential clinical use to enhance healing in the femoral tunnel after ACLR.
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Affiliation(s)
- Adam T Hexter
- Division of Surgery and Interventional Science, University College London, London, UK
| | - Aikaterina Karali
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth, UK
| | - Alex Kao
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth, UK
| | - Gianluca Tozzi
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth, UK
| | - Nima Heidari
- Royal London Hospital and Orthopaedic Specialists (OS), London, UK
| | - Aviva Petrie
- Eastman Dental Institute, University College London, London, UK
| | - Ashleigh Boyd
- Division of Surgery and Interventional Science, University College London, London, UK
| | - Deepak M Kalaskar
- Division of Surgery and Interventional Science, University College London, London, UK
| | - Catherine Pendegrass
- Division of Surgery and Interventional Science, University College London, London, UK
| | - Scott Rodeo
- Hospital of Special Surgery, New York, New York, USA
| | | | - Gordon Blunn
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, UK
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Karali A, Kao AP, Zekonyte J, Blunn G, Tozzi G. Micromechanical evaluation of cortical bone using in situ XCT indentation and digital volume correlation. J Mech Behav Biomed Mater 2021; 115:104298. [PMID: 33445104 DOI: 10.1016/j.jmbbm.2020.104298] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 12/22/2020] [Accepted: 12/25/2020] [Indexed: 11/29/2022]
Abstract
The overall mechanical behaviour of cortical bone is strongly dependant on its microstructure. X-ray computed tomography (XCT) has been widely used to identify the microstructural morphology of cortical tissue (i.e. pore network, Haversian and Volkmann's canals). However, the connection between microstructure and mechanics of cortical bone during plastic deformation is unclear. Hence, the purpose of this study is to provide an in-depth evaluation of the interplay of plastic strain building up in relation to changes in the canal network for cortical bone tissue. In situ step-wise XCT indentation was used to introduce a localised load on the surface of the tissue and digital volume correlation (DVC) was employed to assess the three-dimensional (3D) full-field plastic strain distribution in proximity of the indent. It was observed that regions adjacent to the imprint were under tensile strain, whereas the volume underneath experienced compressive strain. Canal loss and disruption was detected in regions of higher compressive strains exceeding -20000 με and crack formation occurred in specimens where Haversian canals were running parallel to the indentation tip. The results of this study outline the relationship between the micromechanical and structural behaviour of cortical bone during plastic deformation, providing information on cortical tissue fracture pathways.
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Affiliation(s)
- Aikaterina Karali
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth, UK.
| | | | - Jurgita Zekonyte
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth, UK
| | - Gordon Blunn
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, UK.
| | - Gianluca Tozzi
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth, UK.
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Karali A, Kao AP, Meeson R, Roldo M, Blunn GW, Tozzi G. Full-field strain of regenerated bone tissue in a femoral fracture model. J Microsc 2020; 285:156-166. [PMID: 32530049 DOI: 10.1111/jmi.12937] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 05/29/2020] [Accepted: 06/10/2020] [Indexed: 02/06/2023]
Abstract
The mechanical behaviour of regenerated bone tissue during fracture healing is key in determining its ability to withstand physiological loads. However, the strain distribution in the newly formed tissue and how this influences the way a fracture heals it is still unclear. X-ray Computed Tomography (XCT) has been extensively used to assess the progress of mineralised tissues in regeneration and when combined with in situ mechanics and digital volume correlation (DVC) has been proven a powerful tool to understand the mechanical behaviour and full-field three-dimensional (3D) strain distribution in bone. The purpose of this study is therefore to use in situ XCT mechanics and DVC to investigate the strain distribution and load-bearing capacity in a regenerating fracture in the diaphyseal bone, using a rodent femoral fracture model stabilised by external fixation. Rat femurs with 1 mm and 2 mm osteotomy gaps were tested under in situ XCT step-wise compression in the apparent elastic region. High strain was present in the newly formed bone (εp1 and εp3 reaching 29 000 µε and -43 000 µε, respectively), with a wide variation and inhomogeneity of the 3D strain distribution in the regenerating tissues of the fracture gap, which is directly related to the presence of unmineralised tissue observed in histological images. The outcomes of this study will contribute in understanding natural regenerative ability of bone and its mechanical behaviour under loading.
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Affiliation(s)
- A Karali
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth, UK
| | - A P Kao
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth, UK
| | - R Meeson
- Royal Veterinary College, Hatfield, Hertfordshire, UK
| | - M Roldo
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, UK
| | - G W Blunn
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, UK
| | - G Tozzi
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth, UK
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Tozzi G, Peña Fernández M, Davis S, Karali A, Kao AP, Blunn G. Full-Field Strain Uncertainties and Residuals at the Cartilage-Bone Interface in Unstained Tissues Using Propagation-Based Phase-Contrast XCT and Digital Volume Correlation. Materials (Basel) 2020; 13:E2579. [PMID: 32516970 PMCID: PMC7321571 DOI: 10.3390/ma13112579] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/02/2020] [Accepted: 06/03/2020] [Indexed: 01/02/2023]
Abstract
A deeper understanding of the cartilage-bone mechanics is fundamental to unravel onset and progression of osteoarthritis, enabling better diagnosis and treatment. The aim of this study is therefore to explore the capability of X-ray computed (XCT) phase-contrast imaging in a lab-based system to enable digital volume correlation (DVC) measurements of unstained cartilage-bone plugs from healthy adult bovines. DVC strain uncertainties were computed for both articular cartilage and mineralized tissue (calcified cartilage and subchondral bone) in the specimens at increasing propagation distances, ranging from absorption up to four times (4× such effective distance. In addition, a process of dehydration and rehydration was proposed to improve feature recognition in XCT of articular cartilage and mechanical properties of this tissue during the process were assessed via micromechanical probing (indentation), which was also used to determine the effect of long X-ray exposure. Finally, full-field strain from DVC was computed to quantify residual strain distribution at the cartilage-bone interface following unconfined compression test (ex situ). It was found that enhanced gray-scale feature recognition at the cartilage-bone interface was achieved using phase-contrast, resulting in reduced DVC strain uncertainties compared to absorption. Residual strains up to ~7000 µε in the articular cartilage were transferred to subchondral bone via the calcified cartilage and micromechanics revealed the predominant effect of long phase-contrast X-ray exposure in reducing both stiffness and hardness of the articular cartilage. The results of this study will pave the way for further development and refinement of the techniques, improving XCT-based strain measurements in cartilage-bone and other soft-hard tissue interfaces.
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Affiliation(s)
- Gianluca Tozzi
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth PO1 3DJ, UK; (M.P.F.); (A.K.); (A.P.K.)
| | - Marta Peña Fernández
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth PO1 3DJ, UK; (M.P.F.); (A.K.); (A.P.K.)
- School of Engineering Sciences, KTH Royal Institute of Technology, 100 44 Stockholm, Sweden
| | - Sarah Davis
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth PO1 2DT, UK; (S.D.); (G.B.)
| | - Aikaterina Karali
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth PO1 3DJ, UK; (M.P.F.); (A.K.); (A.P.K.)
| | - Alexander Peter Kao
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth PO1 3DJ, UK; (M.P.F.); (A.K.); (A.P.K.)
| | - Gordon Blunn
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth PO1 2DT, UK; (S.D.); (G.B.)
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Peña Fernández M, Dall'Ara E, Kao AP, Bodey AJ, Karali A, Blunn GW, Barber AH, Tozzi G. Preservation of Bone Tissue Integrity with Temperature Control for In Situ SR-MicroCT Experiments. Materials (Basel) 2018; 11:ma11112155. [PMID: 30388813 PMCID: PMC6266162 DOI: 10.3390/ma11112155] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 10/24/2018] [Accepted: 10/30/2018] [Indexed: 01/08/2023]
Abstract
Digital volume correlation (DVC), combined with in situ synchrotron microcomputed tomography (SR-microCT) mechanics, allows for 3D full-field strain measurement in bone at the tissue level. However, long exposures to SR radiation are known to induce bone damage, and reliable experimental protocols able to preserve tissue properties are still lacking. This study aims to propose a proof-of-concept methodology to retain bone tissue integrity, based on residual strain determination using DVC, by decreasing the environmental temperature during in situ SR-microCT testing. Compact and trabecular bone specimens underwent five consecutive full tomographic data collections either at room temperature or 0 °C. Lowering the temperature seemed to reduce microdamage in trabecular bone but had minimal effect on compact bone. A consistent temperature gradient was measured at each exposure period, and its prolonged effect over time may induce localised collagen denaturation and subsequent damage. DVC provided useful information on irradiation-induced microcrack initiation and propagation. Future work is necessary to apply these findings to in situ SR-microCT mechanical tests, and to establish protocols aiming to minimise the SR irradiation-induced damage of bone.
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Affiliation(s)
- Marta Peña Fernández
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, PO1 3DJ, Portsmouth, UK.
| | - Enrico Dall'Ara
- Department of Oncology and Metabolism and INSIGNEO Institute for in Silico Medicine, University of Sheffield, S1 3DJ, Sheffield, UK.
| | - Alexander P Kao
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, PO1 3DJ, Portsmouth, UK.
| | | | - Aikaterina Karali
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, PO1 3DJ, Portsmouth, UK.
| | - Gordon W Blunn
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, PO1 2DT, Portsmouth, UK.
| | - Asa H Barber
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, PO1 3DJ, Portsmouth, UK.
- School of Engineering, London South Bank University, SE1 0AA, London, UK.
| | - Gianluca Tozzi
- Zeiss Global Centre, School of Mechanical and Design Engineering, University of Portsmouth, PO1 3DJ, Portsmouth, UK.
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Nemčovská E, Garabášová M, Kállayová D, Majdan M, Rafajdus M, Rusnák M, Grendová K, Počrvina GO, Marcu O, Savova S, Vassileva S, Marinković S, Popović A, Stanković J, Stošić D, Karali A. Financial literacy for Roma – How to determine health of Roma communities? Eur J Public Health 2016. [DOI: 10.1093/eurpub/ckw174.083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Voulgari PV, Karali A, Alymara V, Chaidos A, Bourantas KL, Drosos AA. Systemic lupus erythematosus in a patient with beta-thalassemia major. Clin Exp Rheumatol 2005; 23:278. [PMID: 15895910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
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Karagkiozaki V, Borghi L, Litsas I, Gotsis A, Terzi S, Passalidou M, Kerameas N, Karali A, Risggits A, Koutsogiannis O. M.553 The effect of simvastatin on C-reactive protein in dyslipidemic patients with or without coronary artery disease. ATHEROSCLEROSIS SUPP 2004. [DOI: 10.1016/s1567-5688(04)90551-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Karali A, Russell P, Stefani FH, Tamm ER. Localization of myocilin/trabecular meshwork--inducible glucocorticoid response protein in the human eye. Invest Ophthalmol Vis Sci 2000; 41:729-40. [PMID: 10711688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
PURPOSE To study distribution and cellular localization of myocilin/trabecular meshwork-inducible glucocorticoid response protein (TIGR) in the human eye. METHODS A peptide antibody against a portion of the myosin-like domain of myocilin/TIGR was developed. Different ocular tissues from three human donors were investigated by one- and two-dimensional gel electrophoresis and Western blot analysis. Immunohistochemistry was performed on 25 human eyes enucleated because of posterior choroidal melanoma and on 7 normal human donor eyes. RESULTS By Western blot analysis, a band at approximately 57 kDa was visualized in cornea, trabecular meshwork, lamina cribrosa, optic nerve, retina, iris, ciliary body, and vitreous humor. By immunohistochemistry, immunoreactivity for myocilin/TIGR was observed in cells of the corneal epi- and endothelium and extracellularly in the corneal stroma and sclera. In the trabecular meshwork, cells of the uveal and corneoscleral meshwork were stained, as was the cribriform area directly adjacent to Schlemm's canal. Positive staining was seen in cells of the ciliary epithelium, ciliary muscle, lens epithelium, and in stromal and smooth muscle cells of the iris. Throughout the entire vitreous body, fine filamentous material was positively labeled. In the retina, staining was seen along the outer surface of rods and cones, in neurons of the inner and outer nuclear layer, and in the axons of optic nerve ganglion cells. Optic nerve axons were stained in the prelaminar, laminar, and postlaminar parts of the nerve. In the region of the lamina cribrosa, astrocytes in the glial columns and cribriform plates were positively labeled. CONCLUSIONS Myocilin TIGR is expressed in almost every ocular tissue. Depending on the respective tissue, it is observed extra- or intracellularly. The presence of myocilin/TIGR in optic nerve axons and lamina cribrosa astrocytes indicates that the trabecular meshwork might not be the only target of abnormal myocilin/TIGR in GLC1A-linked open-angle glaucoma.
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Affiliation(s)
- A Karali
- Department of Anatomy II, University of Erlangen-Nürnberg, Erlangen, Germany
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