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Baer K, Kieser S, Schon B, Rajendran K, Ten Harkel T, Ramyar M, Löbker C, Bateman C, Butler A, Raja A, Hooper G, Anderson N, Woodfield T. Spectral CT imaging of human osteoarthritic cartilage via quantitative assessment of glycosaminoglycan content using multiple contrast agents. APL Bioeng 2021; 5:026101. [PMID: 33834156 PMCID: PMC8018795 DOI: 10.1063/5.0035312] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 02/22/2021] [Indexed: 01/06/2023] Open
Abstract
Detection of early osteoarthritis to stabilize or reverse the damage to articular cartilage would improve patient function, reduce disability, and limit the need for joint replacement. In this study, we investigated nondestructive photon-processing spectral computed tomography (CT) for the quantitative measurement of the glycosaminoglycan (GAG) content compared to destructive histological and biochemical assay techniques in normal and osteoarthritic tissues. Cartilage-bone cores from healthy bovine stifles were incubated in 50% ioxaglate (Hexabrix®) or 100% gadobenate dimeglumine (MultiHance®). A photon-processing spectral CT (MARS) scanner with a CdTe-Medipix3RX detector imaged samples. Calibration phantoms of ioxaglate and gadobenate dimeglumine were used to determine iodine and gadolinium concentrations from photon-processing spectral CT images to correlate with the GAG content measured using a dimethylmethylene blue assay. The zonal distribution of GAG was compared between photon-processing spectral CT images and histological sections. Furthermore, discrimination and quantification of GAG in osteoarthritic human tibial plateau tissue using the same contrast agents were demonstrated. Contrast agent concentrations were inversely related to the GAG content. The GAG concentration increased from 25 μg/ml (85 mg/ml iodine or 43 mg/ml gadolinium) in the superficial layer to 75 μg/ml (65 mg/ml iodine or 37 mg/ml gadolinium) in the deep layer of healthy bovine cartilage. Deep zone articular cartilage could be distinguished from subchondral bone by utilizing the material decomposition technique. Photon-processing spectral CT images correlated with histological sections in healthy and osteoarthritic tissues. Post-imaging material decomposition was able to quantify the GAG content and distribution throughout healthy and osteoarthritic cartilage using Hexabrix® and MultiHance® while differentiating the underlying subchondral bone.
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Affiliation(s)
| | - Sandra Kieser
- Christchurch Regenerative Medicine and Tissue Engineering (CReaTE), Department of Orthopaedic Surgery and Musculoskeletal Medicine, University of Otago Christchurch, Christchurch 8011, New Zealand
| | | | | | | | - Mohsen Ramyar
- Department of Radiology, University of Otago Christchurch, Christchurch 8011, New Zealand
| | | | - Christopher Bateman
- Department of Radiology, University of Otago Christchurch, Christchurch 8011, New Zealand
| | | | | | | | - Nigel Anderson
- Department of Radiology, University of Otago Christchurch, Christchurch 8011, New Zealand
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Anitha DP, Baum T, Kirschke JS, Subburaj K. Effect of the intervertebral disc on vertebral bone strength prediction: a finite-element study. Spine J 2020; 20:665-671. [PMID: 31841703 DOI: 10.1016/j.spinee.2019.11.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 11/23/2019] [Accepted: 11/25/2019] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Osteoporotic vertebral fractures (OVFs) are a prevalent skeletal condition in the elderly but the mechanism behind these fractures remain unclear due to the complex biomechanical interplay between spinal segments such as the vertebra and intervertebral discs (IVDs). PURPOSE To investigate the biomechanical influence of IVDs by (1) comparing finite element (FE)-predicted failure load with experimentally measured failure load of functional spinal units (FSUs) and (2) comparing this correlation with those of FE-predicted failure load and bone mineral density (BMD) of the single central vertebra with experimentally measured failure load. STUDY DESIGN A computational biomechanical analysis. PATIENT SAMPLE Ten thoracic FSUs consisting of a central vertebra, the adjacent IVDs, and the upper and lower halves of the adjacent vertebrae were harvested from formalin-fixed human donors (4 males, 6 females; mean age of 82±9 years). OUTCOME MEASURES The outcome measures included the prediction of vertebral strength and determination of BMD in FSUs and the single central vertebra and the correlation of both measures with experimentally measured vertebral strength of the FSUs. METHODS The FSUs underwent clinical multidetector computed tomography (MDCT) (spatial resolution: 250×250×600 μm3). BMD was determined for the FSUs from the MDCT images of the central vertebrae. FE-predicted failure load was calculated in the single central vertebra of the FSUs alone and the entire FSUs. Experimentally measured failure load of the FSUs was determined in a uniaxial biomechanical test. RESULTS BMD of the central vertebrae correlated significantly with experimentally measured failure load (R2=0.66, p<.02), whereas FE-predicted failure load of the central vertebra showed no significant correlation with experimentally measured failure load (p=.07). However, FE-predicted failure load of FSUs best predicted experimentally measured failure load of FSUs (R2=0.93, p<.0001). CONCLUSIONS This study demonstrated that routine clinical MDCT images can be an accurate and feasible tool for prediction of OVFs using patient-specific FE analysis of FSU models. CLINICAL SIGNIFICANCE Improved management of OVFs is essential amidst current clinical challenges. Implementation of a vertebral strength assessment tool could result in more accurate prediction of osteoporotic fracture risk and aid clinicians with better targeted early treatment strategies.
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Affiliation(s)
- D Praveen Anitha
- Engineering Product Development (EPD) Pillar, Singapore University of Technology and Design (SUTD), 8 Somapah Road, Singapore 487372
| | - Thomas Baum
- Department of Neuroradiology, Klinikum rechts der Isar, Technische Universitaet Muenchen, Muenchen, Germany
| | - Jan S Kirschke
- Department of Neuroradiology, Klinikum rechts der Isar, Technische Universitaet Muenchen, Muenchen, Germany
| | - Karupppasamy Subburaj
- Engineering Product Development (EPD) Pillar, Singapore University of Technology and Design (SUTD), 8 Somapah Road, Singapore 487372.
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Franklin SP, Stoker AM, Lin ASP, Pownder SL, Burke EE, Bozynski CC, Kuroki K, Guldberg RE, Cook JL, Holmes SP. T1ρ, T2 mapping, and EPIC-µCT Imaging in a Canine Model of Knee Osteochondral Injury. J Orthop Res 2020; 38:368-377. [PMID: 31429976 DOI: 10.1002/jor.24450] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 08/02/2019] [Indexed: 02/04/2023]
Abstract
The dog is the most commonly used large animal model for the study of osteoarthritis. Optimizing methods for assessing cartilage health would prove useful in reducing the number of dogs needed for a valid study of osteoarthritis and cartilage repair. Twelve beagles had critical-sized osteochondral defects created in the medial femoral condyle of both knees. Eight dogs had T1ρ and T2 magnetic resonance imaging (MRI) performed approximately 6 months after defect creation. Following MRI evaluations, all 12 dogs were humanely euthanatized and cartilage samples were obtained from the medial and lateral femoral condyles, medial and lateral tibial plateaus, trochlear groove, and patella for proteoglycan and collagen quantification. Equilibrium partitioning of an ionic contrast (EPIC)-µCT was then performed followed by the histologic assessment of the knees. Correlations between T1ρ, T2, EPIC-µCT and proteoglycan, collagen, and histology scores were assessed using a multivariate analysis accounting for correlations from samples within the same knee and in the same dog. Pearson's correlation coefficients were calculated to assess the strength of significant relationships. Correlations between µCT values and biochemical or histologic assessment were weak to moderately strong (0.09-0.41; p < 0.0001-0.66). There was a weak correlation between the T2 values and cartilage proteoglycan (-0.32; p = 0.04). The correlation between T1ρ values and cartilage proteoglycan were moderately strong (-0.38; p < 0.05) while the strongest correlation was between the T1ρ values and histological assessment of cartilage with a correlation coefficient of 0.58 (p < 0.0001). These data suggest that T1ρ shows promise for possible utility in the translational study of cartilage health and warrants further development in this species. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:368-377, 2020.
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Affiliation(s)
- Samuel P Franklin
- Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, Georgia.,Regenerative Bioscience Center, University of Georgia, Athens, Georgia
| | - Aaron M Stoker
- Thompson Laboratory for Regenerative Orthopaedics, Missouri Orthopaedic Institute, University of Missouri, Columbia, Missouri
| | - Angela S P Lin
- Knight Campus for Accelerating Scientific Impact, University of Oregon, Eugene, Oregon
| | - Sarah L Pownder
- MRI Laboratory, Department of Radiology and Imaging, Hospital for Special Surgery, New York, New York
| | - Emily E Burke
- Veterinary Biosciences and Diagnostic Imaging, College of Veterinary Medicine, University of Georgia, Athens, Georgia
| | - Chantelle C Bozynski
- Thompson Laboratory for Regenerative Orthopaedics, Missouri Orthopaedic Institute, University of Missouri, Columbia, Missouri
| | - Kei Kuroki
- Thompson Laboratory for Regenerative Orthopaedics, Missouri Orthopaedic Institute, University of Missouri, Columbia, Missouri
| | - Robert E Guldberg
- Knight Campus for Accelerating Scientific Impact, University of Oregon, Eugene, Oregon
| | - James L Cook
- Thompson Laboratory for Regenerative Orthopaedics, Missouri Orthopaedic Institute, University of Missouri, Columbia, Missouri
| | - Shannon P Holmes
- Veterinary Biosciences and Diagnostic Imaging, College of Veterinary Medicine, University of Georgia, Athens, Georgia
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Mashiatulla M, Moran MM, Chan D, Li J, Freedman JD, Snyder BD, Grinstaff MW, Plaas A, Sumner DR. Murine articular cartilage morphology and compositional quantification with high resolution cationic contrast-enhanced μCT. J Orthop Res 2017; 35:2740-2748. [PMID: 28471533 PMCID: PMC5671366 DOI: 10.1002/jor.23595] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 04/24/2017] [Indexed: 02/04/2023]
Abstract
Articular cartilage lines the load-bearing surfaces of long bones and undergoes compositional and structural degeneration during osteoarthritis progression. Contrast enhanced microcomputed tomography (μCT) is being applied to a variety of preclinical models, including the mouse, to map structural and compositional properties in 3-D. The thinness (∼30-50 μm) and high cellularity of mouse articular cartilage presents a significant imaging challenge. Our group previously showed that mouse articular cartilage and proteoglycan (PG) content can be assessed by μCT with the ioxagalate-based contrast agent Hexabrix, but the voxel size used (6 μm) was deemed to be barely adequate. The objective of the present study is to assess the utility of a novel contrast agent, CA4+, to quantify mouse articular cartilage morphology and composition with high resolution μCT imaging (3 μm voxels) and to compare the sensitivity of CA4+ and Hexabrix to detect between-group differences. While both contrast agents are iodine-based, Hexabrix is anionic and CA4+ is cationic so they interact differently with negatively charged PGs. With CA4+, a strong correlation was found between non-calcified articular cartilage thickness measurements made with histology and μCT (R2 = 0.72, p < 0.001). Cartilage degeneration-as assessed by loss in volume, thickness, and PG content-was observed in 34-week-old mice when compared to both 7- and 12-week-old mice. High measurement precision was observed with CA4+, with the coefficient of variation after repositioning and re-imaging samples equaling 2.8%, 4.5%, 7.4% and 5.9% for attenuation, thickness, volume, and PG content, respectively. Use of CA4+ allowed increased sensitivity for assessing PG content compared to Hexabrix, but had no advantage for measurement of cartilage thickness or volume. This improvement in imaging should prove useful in preclinical studies of cartilage degeneration and regeneration. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2740-2748, 2017.
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Affiliation(s)
- Maleeha Mashiatulla
- Department of Cell & Molecular Medicine, Rush University Medical Center, Chicago, IL, USA,Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Meghan M. Moran
- Department of Cell & Molecular Medicine, Rush University Medical Center, Chicago, IL, USA
| | - Deva Chan
- Department of Internal Medicine, Rush University Medical Center, Chicago, IL, USA
| | - Jun Li
- Department of Internal Medicine, Rush University Medical Center, Chicago, IL, USA
| | - Jonathan D. Freedman
- Department of Biomedical Engineering and Chemistry, Boston University, Boston, MA, USA
| | - Brian D. Snyder
- Center for Advanced Orthopedic Studies, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Mark W. Grinstaff
- Department of Biomedical Engineering and Chemistry, Boston University, Boston, MA, USA
| | - Anna Plaas
- Department of Internal Medicine, Rush University Medical Center, Chicago, IL, USA,Address for correspondence: D. Rick Sumner, Ph.D., Department of Cell & Molecular Medicine, Rush University Medical Center, 600 South Paulina, Suite 507, Chicago, IL 60612, Phone: 312-942-5501, ; Anna Plaas, Department of Internal Medicine, Rush University Medical Center, 1750 W. Harrison Street, Suite 1413, Chicago, IL 60612, Phone: 312-942-7194,
| | - D. Rick Sumner
- Department of Cell & Molecular Medicine, Rush University Medical Center, Chicago, IL, USA,Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA,Address for correspondence: D. Rick Sumner, Ph.D., Department of Cell & Molecular Medicine, Rush University Medical Center, 600 South Paulina, Suite 507, Chicago, IL 60612, Phone: 312-942-5501, ; Anna Plaas, Department of Internal Medicine, Rush University Medical Center, 1750 W. Harrison Street, Suite 1413, Chicago, IL 60612, Phone: 312-942-7194,
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Newton MD, Hartner SE, Timmons S, Delaney ND, Pirrone MG, Baker KC, Maerz T. Contrast-enhanced μCT of the intervertebral disc: A comparison of anionic and cationic contrast agents for biochemical and morphological characterization. J Orthop Res 2017; 35:1067-1075. [PMID: 27415967 DOI: 10.1002/jor.23364] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 07/02/2016] [Indexed: 02/04/2023]
Abstract
The objective of this study was to quantify and compare the contrast-enhancing properties of the anionic contrast agent ioxaglate/Hexabrix, and cationic contrast agent CA4+ for biochemical and morphological characterization of the intervertebral disc (IVD) via μCT. Optimal contrast agent concentrations were determined by incubating rat lumbar IVDs in dilutions of Hexabrix-320 (20%, 30%, 40%, and 50%) and CA4+ (10, 20, 30, and 40 mg I/ml). μCT imaging was performed at 70 kVp, 114 μA, and 250 ms integration time, 12 μm voxel size. The kinetics of contrast enhancement were quantified with cumulative incubations for 0.5, 1, 2, 12, 16, 20, and 24 h using both agents. Agreement in morphological quantification was assessed via serial scans of the same IVDs. Correlation of attenuation to glycosaminoglycan (GAG) content was determined by enzymatic digestion of IVDs, subsequent μCT imaging, and GAG quantification via dimethylmethylene blue assay. Forty percent Hexabrix and 30 mg I/ml CA4+ were chosen as optimal concentrations. Hexabrix enabled greater delineation of the IVD from surrounding tissues, and CA4+ had the lowest uptake in surrounding soft tissue. Twenty-four hour incubation was sufficient for >99% equilibration of both agents. A high level of agreement was observed in the quantification of IVD volume (ICC = 0.951, r = 0.997) and height (ICC = 0.947, r = 0.991). Both agents exhibited strong linear correlations between μCT attenuation and GAG content (Hexabrix: r = -0.940; CA4+ : r = 0.887). Both agents enable biochemical and morphological quantification of the IVD via contrast-enhanced μCT and are effective tools for preclinical characterization. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1067-1075, 2017.
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Affiliation(s)
- Michael D Newton
- Orthopaedic Research Laboratory, Beaumont Health, 3811W Thirteen Mile Road, Royal Oak, Michigan, 48073
| | - Samantha E Hartner
- Orthopaedic Research Laboratory, Beaumont Health, 3811W Thirteen Mile Road, Royal Oak, Michigan, 48073
| | - Shannon Timmons
- Department of Natural Sciences, Lawrence Technological University, Southfield, Michigan
| | - Nathan D Delaney
- Department of Natural Sciences, Lawrence Technological University, Southfield, Michigan
| | - Michael G Pirrone
- Department of Natural Sciences, Lawrence Technological University, Southfield, Michigan
| | - Kevin C Baker
- Orthopaedic Research Laboratory, Beaumont Health, 3811W Thirteen Mile Road, Royal Oak, Michigan, 48073.,Department of Orthopaedic Surgery, Oakland University-William Beaumont School of Medicine, Rochester, Michigan
| | - Tristan Maerz
- Orthopaedic Research Laboratory, Beaumont Health, 3811W Thirteen Mile Road, Royal Oak, Michigan, 48073.,Department of Orthopaedic Surgery, Oakland University-William Beaumont School of Medicine, Rochester, Michigan
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Quantitative imaging of excised osteoarthritic cartilage using spectral CT. Eur Radiol 2016; 27:384-392. [DOI: 10.1007/s00330-016-4374-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 02/29/2016] [Accepted: 04/18/2016] [Indexed: 12/23/2022]
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7
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Crica LE, Wengenroth J, Tiainen H, Ionita M, Haugen HJ. Enhanced X-ray absorption for micro-CT analysis of low density polymers. JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 2016; 27:805-23. [DOI: 10.1080/09205063.2016.1152856] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Khoury BM, Bigelow EMR, Smith LM, Schlecht SH, Scheller EL, Andarawis-Puri N, Jepsen KJ. The use of nano-computed tomography to enhance musculoskeletal research. Connect Tissue Res 2015; 56:106-19. [PMID: 25646568 PMCID: PMC4755519 DOI: 10.3109/03008207.2015.1005211] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Advances in computed tomography (CT) imaging are opening new avenues toward more precise characterization and quantification of connective tissue microarchitecture. In the last two decades, micro-computed tomography (microCT) has significantly augmented destructive methods for the 3D micro-analysis of tissue structure, primarily in the bone research field. Recently, microCT has been employed in combination with contrast agents to generate contrast-enhanced images of soft tissues that are otherwise difficult to visualize due to their native radiodensity. More recent advances in CT technology have enabled ultra-high resolution imaging by utilizing a more powerful nano-focused X-ray source, such as that found in nano-computed tomography (nanoCT) systems. NanoCT imaging has facilitated the expansion of musculoskeletal research by reducing acquisition time and significantly expanding the range of samples that can be imaged in terms of size, age and tissue-type (bone, muscle, tendon, cartilage, vessels and adipose tissue). We present the application and early results of nanoCT imaging in various tissue types and how this ultra-high resolution imaging modality is capable of characterizing microstructures at levels of details previously not possible. Contrast-enhanced imaging techniques to enable soft-tissue visualization and characterization are also outlined.
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Affiliation(s)
| | | | | | | | - Erica L. Scheller
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Nelly Andarawis-Puri
- Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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Hyaluronic acid enhances the mechanical properties of tissue-engineered cartilage constructs. PLoS One 2014; 9:e113216. [PMID: 25438040 PMCID: PMC4249877 DOI: 10.1371/journal.pone.0113216] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Accepted: 10/20/2014] [Indexed: 11/26/2022] Open
Abstract
There is a need for materials that are well suited for cartilage tissue engineering. Hydrogels have emerged as promising biomaterials for cartilage repair, since, like cartilage, they have high water content, and they allow cells to be encapsulated within the material in a genuinely three-dimensional microenvironment. In this study, we investigated the mechanical properties of tissue-engineered cartilage constructs using in vitro culture models incorporating human chondrocytes from osteoarthritis patients. We evaluated hydrogels formed from mixtures of photocrosslinkable gelatin-methacrylamide (Gel-MA) and varying concentrations (0–2%) of hyaluronic acid methacrylate (HA-MA). Initially, only small differences in the stiffness of each hydrogel existed. After 4 weeks of culture, and to a greater extent 8 weeks of culture, HA-MA had striking and concentration dependent impact on the changes in mechanical properties. For example, the initial compressive moduli of cell-laden constructs with 0 and 1% HA-MA were 29 and 41 kPa, respectively. After 8 weeks of culture, the moduli of these constructs had increased to 66 and 147 kPa respectively, representing a net improvement of 69 kPa for gels with 1% HA-MA. Similarly the equilibrium modulus, dynamic modulus, failure strength and failure strain were all improved in constructs containing HA-MA. Differences in mechanical properties did not correlate with glycosaminoglycan content, which did not vary greatly between groups, yet there were clear differences in aggrecan intensity and distribution as assessed using immunostaining. Based on the functional development with time in culture using human chondrocytes, mixtures of Gel-MA and HA-MA are promising candidates for cartilage tissue-engineering applications.
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Three-dimensional characterization of in vivo intervertebral disc degeneration using EPIC-μCT. Osteoarthritis Cartilage 2014; 22:1918-25. [PMID: 25151083 DOI: 10.1016/j.joca.2014.08.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 07/25/2014] [Accepted: 08/13/2014] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Small animal models are commonly employed to study progression of and potential treatment techniques for degenerative disc disease (DDD), but assessment using conventional imaging techniques is challenging due to resolution. The objective of this study was to employ equilibrium partitioning of an ionic contrast agent micro computed tomography (EPIC - μCT) to map three-dimensional (3D) degenerative changes in the rabbit intervertebral disc (IVD). MATERIALS AND METHODS In vivo degeneration was induced surgically in 12 New Zealand White rabbits via percutaneous annular puncture and percutaneous nucleotomy. IVDs were harvested after 3 and 6 weeks. EPIC-μCT imaging was performed on fresh, IVDs before and after formalin fixation, and 3D IVD volumes were segmented. IVDs were histologically stained with Safranin-O/Fast-Green and Hematoxylin & Eosin (H&E). EPIC-μCT attenuation and 3D morphological measurements were assessed in healthy and degenerate IVDs and compared to qualitative grading and disc height measurement from histology. RESULTS EPIC-μCT caused pronounced contrast enhancement of the IVD. Annular puncture and nucleotomy produced mild and severe degenerative changes, respectively. IVD attenuation following contrast enhancement increased significantly in nucleotomized discs at 3 and 6 weeks. IVD attenuation correlated significantly with histologic score and disc height measurements. Disc height decreased most extensively in the posterior and lateral aspects of the IVD. 3D morphological measurements correlated strongly to IVD attenuation and were more sensitive to degenerative changes than histologic measurements. Formalin fixation reduced the attenuation of IVDs by ∼10%. CONCLUSION EPIC-μCT is sensitive to in vivo DDD induced by nucleotomy and provides a high resolution 3D method for mapping degenerative changes in rabbit IVDs.
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Entezari V, Bansal PN, Stewart RC, Lakin BA, Grinstaff MW, Snyder BD. Effect of mechanical convection on the partitioning of an anionic iodinated contrast agent in intact patellar cartilage. J Orthop Res 2014; 32:1333-40. [PMID: 24961833 DOI: 10.1002/jor.22662] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Accepted: 05/14/2014] [Indexed: 02/04/2023]
Abstract
To determine if mechanical convection accelerates partitioning of an anionic contrast agent into cartilage while maintaining its ability to reflect the glycosaminoglycan (GAG) content in contrast-enhanced computed tomography (CECT) of cartilage. Bovine patellae (N = 4) were immersed in iothalamate and serially imaged over 24 h of passive diffusion at 34°C. Following saline washing for 14 h, each patella was serially imaged over 2.5 h of mechanical convection by cyclic compressive loading (120N, 1 Hz) while immersed in iothalamate at 34°C. After similar saline washing, each patella was sectioned into 15 blocks (n = 60) and contrast concentration per time point as well as GAG content were determined for each cartilage block. Mechanical convection produced 70.6%, 34.4%, and 16.4% higher contrast concentration at 30, 60, and 90 min, respectively, compared to passive diffusion (p < 0.001) and boosted initial contrast flux 330%. The correlation between contrast concentration and GAG content was significant at all time points and correlation coefficients improved with time, reaching R(2) = 0.60 after 180 min of passive diffusion and 22.5 min of mechanical convection. Mechanical convection significantly accelerated partitioning of a contrast agent into healthy cartilage while maintaining strong correlations with GAG content, providing an evidence-based rationale for adopting walking regimens in CECT imaging protocols.
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Affiliation(s)
- Vahid Entezari
- Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, 02215
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Jeon JE, Vaquette C, Theodoropoulos C, Klein TJ, Hutmacher DW. Multiphasic construct studied in an ectopic osteochondral defect model. J R Soc Interface 2014; 11:20140184. [PMID: 24694896 PMCID: PMC4006259 DOI: 10.1098/rsif.2014.0184] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 03/10/2014] [Indexed: 12/22/2022] Open
Abstract
In vivo osteochondral defect models predominantly consist of small animals, such as rabbits. Although they have an advantage of low cost and manageability, their joints are smaller and more easily healed compared with larger animals or humans. We hypothesized that osteochondral cores from large animals can be implanted subcutaneously in rats to create an ectopic osteochondral defect model for routine and high-throughput screening of multiphasic scaffold designs and/or tissue-engineered constructs (TECs). Bovine osteochondral plugs with 4 mm diameter osteochondral defect were fitted with novel multiphasic osteochondral grafts composed of chondrocyte-seeded alginate gels and osteoblast-seeded polycaprolactone scaffolds, prior to being implanted in rats subcutaneously with bone morphogenic protein-7. After 12 weeks of in vivo implantation, histological and micro-computed tomography analyses demonstrated that TECs are susceptible to mineralization. Additionally, there was limited bone formation in the scaffold. These results suggest that the current model requires optimization to facilitate robust bone regeneration and vascular infiltration into the defect site. Taken together, this study provides a proof-of-concept for a high-throughput osteochondral defect model. With further optimization, the presented hybrid in vivo model may address the growing need for a cost-effective way to screen osteochondral repair strategies before moving to large animal preclinical trials.
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Affiliation(s)
| | | | | | | | - Dietmar W. Hutmacher
- Institute of Health and Biomedical Innovation, Queensland University of Technology, 60 Musk Avenue, Kelvin Grove, Queensland 4059, Australia
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13
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Renders GAP, Mulder L, Lin AS, Langenbach GEJ, Koolstra JH, Guldberg RE, Everts V. Contrast-enhanced microCT (EPIC-μCT) ex vivo applied to the mouse and human jaw joint. Dentomaxillofac Radiol 2013; 43:20130098. [PMID: 24353248 DOI: 10.1259/dmfr.20130098] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES The temporomandibular joint (TMJ) is susceptive to the development of osteoarthritis (OA). More detailed knowledge of its development is essential to improve our insight into TMJ-OA. It is imperative to have a standardized reliable three-dimensional (3D) imaging method that allows for detailed assessment of both bone and cartilage in healthy and diseased joints. We aimed to determine the applicability of a contrast-enhanced microCT (µCT) technique for ex vivo research of mouse and human TMJs. METHODS Equilibrium partitioning of an ionic contrast agent via µCT (EPIC-µCT) was previously applied for cartilage assessment in the knee joint. The method was ex vivo, applied to the mouse TMJ and adapted for the human TMJ. RESULTS EPIC-µCT (30-min immersion time) was applied to mouse mandibular condyles, and 3D imaging revealed an average cartilage thickness of 110 ± 16 µm. These measurements via EPIC-µCT were similar to the histomorphometric measures (113 ± 19 µm). For human healthy OA-affected TMJ samples, the protocol was adjusted to an immersion time of 1 h. 3D imaging revealed a significant thicker cartilage layer in joints with early signs of OA compared with healthy joints (414.2 ± 122.6 and 239.7 ± 50.5 µm, respectively). A subsequent significant thinner layer was found in human joints with late signs of OA (197.4 ± 159.7 µm). CONCLUSIONS The EPIC-µCT technique is effective for the ex vivo assessment of 3D cartilage morphology in the mouse as well as human TMJ and allows bone-cartilage interaction research in TMJ-OA.
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Affiliation(s)
- G A P Renders
- Department of Oral Cell Biology and Functional Anatomy, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, Amsterdam, Netherlands
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14
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Hill ML, Gorelikov I, Niroui F, Levitin RB, Mainprize JG, Yaffe MJ, Rowlands JA, Matsuura N. Towards a nanoscale mammographic contrast agent: development of a modular pre-clinical dual optical/x-ray agent. Phys Med Biol 2013; 58:5215-35. [PMID: 23851978 DOI: 10.1088/0031-9155/58/15/5215] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Contrast-enhanced digital mammography (CEDM) can provide improved breast cancer detection and characterization compared to conventional mammography by imaging the effects of tumour angiogenesis. Current small-molecule contrast agents used for CEDM are limited by a short plasma half-life and rapid extravasation into tissue interstitial space. To address these limitations, nanoscale agents that can remain intravascular except at sites of tumour angiogenesis can be used. For CEDM, this agent must be both biocompatible and strongly attenuate mammographic energy x-rays. Nanoscale perfluorooctylbromide (PFOB) droplets have good x-ray attenuation and have been used in patients for other applications. However, the macroscopic scale of x-ray imaging (50-100 µm) is inadequate for direct verification that PFOB droplets localize at sites of breast tumour angiogenesis. For efficient pre-clinical optimization for CEDM, we integrated an optical marker into PFOB droplets for microscopic assessment (≪50 µm). To develop PFOB droplets as a new nanoscale mammographic contrast agent, PFOB droplets were labelled with fluorescent quantum dots (QDs). The droplets had mean diameters of 160 nm, fluoresced at 635 nm and attenuated x-ray spectra at 30.5 keV mean energy with a relative attenuation of 5.6 ± 0.3 Hounsfield units (HU) mg(-1) mL(-1) QD-PFOB. With the agent loaded into tissue phantoms, good correlation between x-ray attenuation and optical fluorescence was found (R(2) = 0.96), confirming co-localization of the QDs with PFOB for quantitative assessment using x-ray or optical methods. Furthermore, the QDs can be removed from the PFOB agent without affecting its x-ray attenuation or structural properties for expedited translation of optimized PFOB droplet formulations into patients.
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Affiliation(s)
- Melissa L Hill
- Physical Sciences, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada
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15
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Lau SF, Wolschrijn CF, Siebelt M, Vernooij JCM, Voorhout G, Hazewinkel HAW. Assessment of articular cartilage and subchondral bone using EPIC-microCT in Labrador retrievers with incipient medial coronoid disease. Vet J 2013; 198:116-21. [PMID: 23846028 DOI: 10.1016/j.tvjl.2013.05.038] [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: 11/01/2012] [Revised: 05/07/2013] [Accepted: 05/27/2013] [Indexed: 01/02/2023]
Abstract
The aetiopathogenesis of medial coronoid disease (MCD) remains obscure, despite its high prevalence. The role of changes to subchondral bone or articular cartilage is much debated. Although there is evidence of micro-damage to subchondral bone, it is not known whether this is a cause or a consequence of MCD, nor is it known whether articular cartilage is modified in the early stages of the disease. The aim of the present study was to use equilibrium partitioning of an ionic contrast agent with micro-computed tomography (microCT) to investigate changes to both the articular cartilage and the subchondral bone of the medial coronoid processes (MCP) of growing Labrador retrievers at an early stage of the disease and at different bodyweights. Of 14 purpose-bred Labrador retrievers (15-27 weeks), six were diagnosed with bilateral MCD and one was diagnosed with unilateral MCD on the basis of microCT studies. The mean X-ray attenuation of articular cartilage was significantly higher in dogs with MCD than in dogs without MCD (P<0.01). In all dogs, the mean X-ray attenuation of articular cartilage was significantly higher at the lateral (P<0.001) than at the proximal aspect of the MCP, indicating decreased glycosaminoglycan content. Changes in parameters of subchondral bone micro-architecture, namely the ratio of bone volume to tissue volume (BV/TV), bone surface density (BS/TV), bone surface to volume ratio (BS/BV), trabecular thickness (Tb.Th; mm), size of marrow cavities described by trabecular spacing (Tb.Sp; mm), and structural model index (SMI), differed significantly by litter (P<0.05) due to the difference in age and weight, but not by the presence/absence of MCD (P>0.05), indicating that subchondral bone density is not affected in early MCD. This study demonstrated that cartilage matrix and not subchondral bone density is affected in the early stages of MCD.
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Affiliation(s)
- S F Lau
- Division of Diagnostic Imaging, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 108, 3584CM Utrecht, The Netherlands; Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, University Putra Malaysia, 43400 Serdang, Malaysia.
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16
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Kotwal N, Li J, Sandy J, Plaas A, Sumner DR. Initial application of EPIC-μCT to assess mouse articular cartilage morphology and composition: effects of aging and treadmill running. Osteoarthritis Cartilage 2012; 20:887-95. [PMID: 22609479 PMCID: PMC3817026 DOI: 10.1016/j.joca.2012.04.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 04/06/2012] [Accepted: 04/13/2012] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The current study was undertaken to adapt Equilibrium Partitioning of an Ionic Contrast agent via microcomputed tomography (EPIC-μCT) to mouse articular cartilage (AC), which presents a particular challenge because it is thin (30 μm) and has a small volume (0.2-0.4 mm(3)), meaning there is only approximately 2-4 μg of chondroitin sulfate (CS) glycosaminoglycan per joint surface cartilage. DESIGN Using 6 μm isotropic voxels and the negatively charged contrast agent ioxaglate (Hexabrix), we optimized contrast agent concentration and incubation time, assessed two methods of tissue preservation (formalin fixation and freezing), examined the effect of ex vivo chondroitinase ABC digestion on X-ray attenuation, assessed accuracy and precision, compared young and skeletally mature cartilage, and determined patterns of degradation in a murine cartilage damage model induced by treadmill running. RESULTS The optimal concentration of the contrast agent was 15%, formalin fixation was preferred to freezing, and 2 h of incubation was needed to reach contrast agent equilibrium with formalin-fixed specimens. There was good agreement with histologic measurements of cartilage thickness, although μCT over-estimated thickness by 13% (5 μm) in 6-week-old mice. Enzymatic release of 0.8 μg of chondrotin sulfate (about 40% of the total) increased X-ray attenuation by 17%. There was a 15% increase in X-ray attenuation in 14-week-old mice compared to 6-week-old mice (P < 0.001) and this corresponded to 65% decrease in CS content at 14 weeks. The older mice also had reductions of 33% in cartilage thickness and 44% in cartilage volume (P < 0.001). Treadmill running induced a 16% decrease in cartilage thickness (P = 0.012) and a 12% increase in X-ray attenuation (P = 0.006) in 14-week-old mice. CONCLUSION This technique enables non-destructive visualization and quantification of murine femoral AC in three dimensions with anatomic specificity and should prove to be a useful new tool in studying degeneration of cartilage in mouse models.
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Affiliation(s)
- Naomi Kotwal
- Department of Anatomy & Cell Biology, Rush University Medical Center, Chicago, IL
| | - Jun Li
- Department of Internal Medicine (Rheumatology), Rush University Medical Center, Chicago, IL
| | - John Sandy
- Department of Biochemistry, Rush University Medical Center, Chicago, IL
| | - Anna Plaas
- Department of Internal Medicine (Rheumatology), Rush University Medical Center, Chicago, IL,Department of Biochemistry, Rush University Medical Center, Chicago, IL
| | - D. Rick Sumner
- Department of Anatomy & Cell Biology, Rush University Medical Center, Chicago, IL,Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL
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