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Shazeeb MS, Howes S, Kandasamy S, Peiris TB, Sotak CH, Pins GD. Developing quantitative MRI parameters to characterize host response and tissue ingrowth into collagen scaffolds. NMR IN BIOMEDICINE 2019; 32:e4059. [PMID: 30657204 DOI: 10.1002/nbm.4059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 11/19/2018] [Accepted: 11/20/2018] [Indexed: 06/09/2023]
Abstract
The in vivo evaluation of soft biomaterial implant remodeling routinely requires the surgical removal of the implant for subsequent histological assessment of tissue ingrowth and scaffold remodeling. This approach is very resource intensive, often destructive, and imposes practical limitations on how effectively these materials can be evaluated. MRI has the potential to non-invasively monitor the remodeling of implanted collagen scaffolds in real time. This study investigated the development of a model system to characterize the cellular infiltration, void area fraction, and angiogenesis in collagen scaffold implants using T2 relaxation time and apparent diffusion coefficient (ADC) maps along with conventional histological techniques. Initial correlations found statistically significant relationships between the MRI and histological parameters for various regions of the implanted sponges: T2 versus cell density (r ≈ -0.83); T2 versus void area fraction (r ≈ +0.78); T2 versus blood vessel density (r ≈ +0.95); ADC versus cell density (r ≈ -0.77); and ADC versus void area fraction (r ≈ +0.84). This suggests that MRI is sensitive to specific remodeling parameters and has the potential to serve as a non-invasive tool to monitor the remodeling of implanted collagen scaffolds, and to ultimately assess the ability of these scaffolds to regenerate the functional properties of damaged tissues such as tendons, ligaments, skin or skeletal muscle.
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Affiliation(s)
- Mohammed Salman Shazeeb
- Department of Radiology, University of Massachusetts Medical School, Worcester, MA, USA
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA, USA
| | - Stuart Howes
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA, USA
| | - Sivakumar Kandasamy
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA, USA
| | - Thelge Buddika Peiris
- Department of Mathematical Sciences, Worcester Polytechnic Institute, Worcester, MA, USA
| | - Christopher H Sotak
- Department of Radiology, University of Massachusetts Medical School, Worcester, MA, USA
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA, USA
- Department of Chemistry & Biochemistry, Worcester Polytechnic Institute, Worcester, MA, USA
| | - George D Pins
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA, USA
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2
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Fujihara Y, Nitta N, Misawa M, Hyodo K, Shirasaki Y, Hayashi K, Kosaka R, Homma K, Numano T, Kuribayashi S, Watanabe Y, Sato J, Ohtomo K, Takato T, Hoshi K. T2 and Apparent Diffusion Coefficient of MRI Reflect Maturation of Tissue-Engineered Auricular Cartilage Subcutaneously Transplanted in Rats. Tissue Eng Part C Methods 2016; 22:429-38. [DOI: 10.1089/ten.tec.2015.0291] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Yuko Fujihara
- Department of Oral and Maxillofacial Surgery, The University of Tokyo Hospital, Tokyo, Japan
| | - Naotaka Nitta
- Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Masaki Misawa
- Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Koji Hyodo
- Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Yoshio Shirasaki
- Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Kazuhiko Hayashi
- Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Ryo Kosaka
- Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Kazuhiro Homma
- Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Tomokazu Numano
- Department of Radiological Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Shouta Kuribayashi
- Department of Radiological Science, Faculty of Health Science, Komazawa University, Tokyo, Japan
| | - Yasushi Watanabe
- Department of Radiology, The University of Tokyo Hospital, Tokyo, Japan
| | - Jiro Sato
- Department of Radiology, The University of Tokyo Hospital, Tokyo, Japan
| | - Kuni Ohtomo
- Department of Radiology, The University of Tokyo Hospital, Tokyo, Japan
| | - Tsuyoshi Takato
- Department of Oral and Maxillofacial Surgery, The University of Tokyo Hospital, Tokyo, Japan
| | - Kazuto Hoshi
- Department of Oral and Maxillofacial Surgery, The University of Tokyo Hospital, Tokyo, Japan
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3
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Chen J, Zhu X, Xu Y, Tang Y, Xiong S, Zhuo S, Chen J. Stereoscopic visualization and quantification of auricular cartilage regeneration in rabbits using multiphoton microscopy. SCANNING 2014; 36:540-546. [PMID: 25195587 DOI: 10.1002/sca.21153] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 07/15/2014] [Indexed: 06/03/2023]
Abstract
Multiphoton microscopy (MPM) was applied for imaging and quantifying the elastic cartilage regeneration tissue in a rabbit ear model without using labeling agents. Morphology of cells and collagen matrix were analysis, showing significant difference between regenerated and intact cartilage in cellular size and collagen distribution. The results demonstrate that high resolution images provide by MPM are consistent with the histological results, and show additional biological behavior which is not visible in standard histology. Advantages in instrumentation may lead to the application of MPM for intravital detection and treatment.
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Affiliation(s)
- Jing Chen
- Institute of Laser and Optoelectronics Technology, Fujian Provincial Key Laboratory for Photonics Technology, Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education, Fujian Normal University, Fuzhou, P. R. China
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4
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Appel AA, Anastasio MA, Larson JC, Brey EM. Imaging challenges in biomaterials and tissue engineering. Biomaterials 2013; 34:6615-30. [PMID: 23768903 PMCID: PMC3799904 DOI: 10.1016/j.biomaterials.2013.05.033] [Citation(s) in RCA: 167] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 05/18/2013] [Indexed: 12/11/2022]
Abstract
Biomaterials are employed in the fields of tissue engineering and regenerative medicine (TERM) in order to enhance the regeneration or replacement of tissue function and/or structure. The unique environments resulting from the presence of biomaterials, cells, and tissues result in distinct challenges in regards to monitoring and assessing the results of these interventions. Imaging technologies for three-dimensional (3D) analysis have been identified as a strategic priority in TERM research. Traditionally, histological and immunohistochemical techniques have been used to evaluate engineered tissues. However, these methods do not allow for an accurate volume assessment, are invasive, and do not provide information on functional status. Imaging techniques are needed that enable non-destructive, longitudinal, quantitative, and three-dimensional analysis of TERM strategies. This review focuses on evaluating the application of available imaging modalities for assessment of biomaterials and tissue in TERM applications. Included is a discussion of limitations of these techniques and identification of areas for further development.
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Affiliation(s)
- Alyssa A. Appel
- Department of Biomedical Engineering, Illinois Institute of Technology, 3255 South Dearborn St, Chicago, IL 60616, USA
- Research Service, Hines Veterans Administration Hospital, Hines, IL, USA
| | - Mark A. Anastasio
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Jeffery C. Larson
- Department of Biomedical Engineering, Illinois Institute of Technology, 3255 South Dearborn St, Chicago, IL 60616, USA
- Research Service, Hines Veterans Administration Hospital, Hines, IL, USA
| | - Eric M. Brey
- Department of Biomedical Engineering, Illinois Institute of Technology, 3255 South Dearborn St, Chicago, IL 60616, USA
- Research Service, Hines Veterans Administration Hospital, Hines, IL, USA
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5
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Smith Callahan LA, Childers EP, Bernard SL, Weiner SD, Becker ML. Maximizing phenotype constraint and extracellular matrix production in primary human chondrocytes using arginine-glycine-aspartate concentration gradient hydrogels. Acta Biomater 2013; 9:7420-8. [PMID: 23567942 DOI: 10.1016/j.actbio.2013.04.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 03/01/2013] [Accepted: 04/01/2013] [Indexed: 01/30/2023]
Abstract
New systematic approaches are necessary to determine and optimize the chemical and mechanical scaffold properties for hyaline cartilage generation using the limited cell numbers obtained from primary human sources. Peptide functionalized hydrogels possessing continuous variations in physico-chemical properties are an efficient three-dimensional platform for studying several properties simultaneously. Herein, we describe a polyethylene glycol dimethacrylate (PEGDM) hydrogel system possessing a gradient of arginine-glycine-aspartic acid peptide (RGD) concentrations from 0mM to 10mM. The system is used to correlate primary human osteoarthritic chondrocyte proliferation, phenotype maintenance and extracellular matrix (ECM) production to the gradient hydrogel properties. Cell number and chondrogenic phenotype (CD14:CD90 ratios) were found to decline in regions with higher RGD concentrations, while regions with lower RGD concentrations maintained cell number and phenotype. Over three weeks of culture, hydrogel regions containing lower RGD concentrations experience an increase in ECM content compared to regions with higher RGD concentrations. Variations in actin amounts and vinculin organization were observed within the RGD concentration gradients that contribute to the differences in chondrogenic phenotype maintenance and ECM expression.
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6
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Kotecha M, Klatt D, Magin RL. Monitoring cartilage tissue engineering using magnetic resonance spectroscopy, imaging, and elastography. TISSUE ENGINEERING PART B-REVIEWS 2013; 19:470-84. [PMID: 23574498 DOI: 10.1089/ten.teb.2012.0755] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A key technical challenge in cartilage tissue engineering is the development of a noninvasive method for monitoring the composition, structure, and function of the tissue at different growth stages. Due to its noninvasive, three-dimensional imaging capabilities and the breadth of available contrast mechanisms, magnetic resonance imaging (MRI) techniques can be expected to play a leading role in assessing engineered cartilage. In this review, we describe the new MR-based tools (spectroscopy, imaging, and elastography) that can provide quantitative biomarkers for cartilage tissue development both in vitro and in vivo. Magnetic resonance spectroscopy can identify the changing molecular structure and alternations in the conformation of major macromolecules (collagen and proteoglycans) using parameters such as chemical shift, relaxation rates, and magnetic spin couplings. MRI provides high-resolution images whose contrast reflects developing tissue microstructure and porosity through changes in local relaxation times and the apparent diffusion coefficient. Magnetic resonance elastography uses low-frequency mechanical vibrations in conjunction with MRI to measure soft tissue mechanical properties (shear modulus and viscosity). When combined, these three techniques provide a noninvasive, multiscale window for characterizing cartilage tissue growth at all stages of tissue development, from the initial cell seeding of scaffolds to the development of the extracellular matrix during construct incubation, and finally, to the postimplantation assessment of tissue integration in animals and patients.
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Affiliation(s)
- Mrignayani Kotecha
- Department of Bioengineering, University of Illinois at Chicago , Chicago, Illinois
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7
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Smith Callahan LA, Ganios AM, Childers EP, Weiner SD, Becker ML. Primary human chondrocyte extracellular matrix formation and phenotype maintenance using RGD-derivatized PEGDM hydrogels possessing a continuous Young's modulus gradient. Acta Biomater 2013; 9:6095-104. [PMID: 23291491 DOI: 10.1016/j.actbio.2012.12.028] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 12/20/2012] [Accepted: 12/21/2012] [Indexed: 11/26/2022]
Abstract
Efficient ex vivo methods for expanding primary human chondrocytes while maintaining the phenotype is critical to advancing the sourcing of autologous cells for tissue engineering applications. While there has been significant research reported in the literature, systematic approaches are necessary to determine and optimize the chemical and mechanical scaffold properties for hyaline cartilage generation using limited cell numbers. Functionalized hydrogels possessing continuous variations in physico-chemical properties are, therefore, an efficient three-dimensional platform for studying several properties simultaneously. Herein we describe a polyethylene glycol dimethacrylate (PEGDM) hydrogel system with a modulus gradient (~27,000-3800 Pa) containing a uniform concentration of arginine-glycine-aspartic acid (RGD) peptide to enhance cell adhesion in order to correlate primary human osteoarthritic chondrocyte proliferation, phenotype maintenance, and extracellular matrix (ECM) production with hydrogel properties. Cell number and chondrogenic phenotype (CD14:CD90 ratios) were found to decline in regions with a higher storage modulus (>13,100 Pa), while regions with a lower storage modulus maintained their cell number and phenotype. Over 3 weeks culture hydrogel regions possessing a lower Young's modulus experienced an increase in ECM content (~200%) compared with regions with a higher storage modulus. Variations in the amount and organization of the cytoskeletal markers actin and vinculin were observed within the modulus gradient, which are indicative of differences in chondrogenic phenotype maintenance and ECM expression. Thus scaffold mechanical properties have a significant impact in modulating human osteoarthritic chondrocyte behavior and tissue formation.
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8
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Nürnberger S, Meyer C, Ponomarev I, Barnewitz D, Resinger C, Klepal W, Albrecht C, Marlovits S. Equine articular chondrocytes on MACT scaffolds for cartilage defect treatment. Anat Histol Embryol 2013; 42:332-43. [PMID: 23323689 DOI: 10.1111/ahe.12018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 10/12/2012] [Indexed: 11/29/2022]
Abstract
Treatment of cartilage defects poses challenging problems in human and veterinary medicine, especially in horses. This study examines the suitability of applying scaffold materials similar to those used for human cartilage regeneration on equine chondrocytes. Chondrocytes gained from biopsies of the talocrural joint of three horses were propagated in 2D culture and grown on two different scaffold materials, hyaluronan (HYAFF®) and collagen (BioGide®), and evaluated by light and electron microscopy. The equine chondrocytes developed well in both types of materials. They were vital and physiologically highly active. On the surface of the scaffolds, they formed cell multilayers. Inside the hyaluronan web, the chondrocytes were regularly distributed and spanned the large scaffold fibre distances by producing their own matrix sheath. Half-circle-like depressions occasionally found in the cell membrane were probably related to movement on the flexible matrix sheath. Inside the dense collagen scaffold, only single cells were found. They passed through the scaffold strands by cell shape adaptation. This study showed that the examined scaffold materials can be used for equine chondrocyte cultivation. Chondrocytes tend to form multilayers on the surface of both, very dense and very porous scaffolds, and have strategies to span between and move in large gaps.
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Affiliation(s)
- S Nürnberger
- Department of Traumatology, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria; Ludwig Boltzmann Institute for Experimental and Clinical Traumatology in AUVA Research Center, Donaueschingenstrasse 13, 1200, Vienna, Austria; Austrian Cluster for Tissue Regeneration, Donaueschingenstrasse 13, 1200, Vienna, Austria
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9
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Rodriguez-Merchan EC. Regeneration of articular cartilage of the knee. Rheumatol Int 2012; 33:837-45. [PMID: 23263546 DOI: 10.1007/s00296-012-2601-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Accepted: 12/08/2012] [Indexed: 01/09/2023]
Abstract
Cartilage therapy for focal articular lesions of the knee has been implemented for more than a decade, and it is becoming increasingly available. What do we know on the healing response of cartilage lesions? What do we know on the treatment of focal cartilage lesions of the knee and the prognostic factors involved? PubMed articles related to articular cartilage regeneration of the knee in clinical studies were searched from January 2006 to November 2012, using the following key words: articular cartilage, regeneration, clinical studies, and knee. A total of 44 reports were found. They showed the following possibilities for the treatment of focal lesions of the articular cartilage of the knee: cartilage regeneration and repair including cartilage reparation with gene-activated matrices, autologous chondrocyte implantation (ACI) and matrix-induced ACI (MACI), microfracture, osteochondral autograft transfer (mosaicplasty), biological approaches (scaffolds, mesenchymal stem cells-MSCs, platelet-rich plasma, growing factors-GF, bone morphogenetic proteins-BMPs, magnetically labeled synovium-derived cells-M-SDCs, and elastic-like polypeptide gels), osteotomies, stem-cell-coated titanium implants, and chondroprotection with pulsed electromagnetic fields. Untreated cartilage lesions on the femoral condyles had a superior healing response compared to those on the tibial plateaus, and in the patellofemoral joint. Clinical outcome regarding the treatment of medial defects is better than that of the lateral defects. Improvement from baseline was better for patients < or = 30 years compared with patients > or = 30 years. ACI, MACI, and mosaicplasty have shown similar results. The results of comparative clinical studies using ACI have shown some superiority over conventional microfracturing in medium or large defects and in long-term durability. Some biological methods such as scaffolds, MSCs, GF, M-SDCs, BMPs, and elastic-like polypeptide gels still need more research.
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Affiliation(s)
- E Carlos Rodriguez-Merchan
- Department of Orthopaedic Surgery, La Paz University Hospital, Paseo de la Castellana 261, 28046 Madrid, Spain.
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10
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Callahan LAS, Ganios AM, McBurney DL, Dilisio MF, Weiner SD, Horton WE, Becker ML. ECM production of primary human and bovine chondrocytes in hybrid PEG hydrogels containing type I collagen and hyaluronic acid. Biomacromolecules 2012; 13:1625-31. [PMID: 22559049 DOI: 10.1021/bm3003336] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The development of advanced materials that facilitate hyaline cartilage formation and regeneration in aging populations is imperative. Critical to the success of this endeavor is the optimization of ECM production from clinically relevant cells. However, much of the current literature focuses on the investigation of primary bovine chondrocytes from young calves, which differ significantly than osteoarthritic cells from human sources. This study examines the levels of extracellular matrix (ECM) production using various levels of type I collagen and hyaluronic acid in poly(ethylene glycol) dimethacrylate (PEGDM) hydrogels in total knee arthroplasties, compared with the results from bovine chondrocytes. The addition of type 1 collagen in both the presence and absence of low levels of hyaluronic acid increased ECM production and/or retention in scaffolds containing either bovine or human chondrocytes. These findings are supported consistently with colorimetric quantification, whole mount extracellular matrix staining for both cell types, and histological staining for glycoaminoglycans and collagen of human chondrocyte containing samples. While exhibiting similar trends, the relative ECM productions levels for the primary human chondrocytes are significantly less than the bovine chondrocytes which reinforces the need for additional optimization.
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11
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Reiter DA, Irrechukwu O, Lin PC, Moghadam S, Von Thaer S, Pleshko N, Spencer RG. Improved MR-based characterization of engineered cartilage using multiexponential T2 relaxation and multivariate analysis. NMR IN BIOMEDICINE 2012; 25:476-88. [PMID: 22287335 PMCID: PMC3366280 DOI: 10.1002/nbm.1804] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 08/30/2011] [Accepted: 09/23/2011] [Indexed: 05/27/2023]
Abstract
Noninvasive monitoring of tissue quality would be of substantial use in the development of cartilage tissue engineering strategies. Conventional MR parameters provide noninvasive measures of biophysical tissue properties and are sensitive to changes in matrix development, but do not clearly distinguish between groups with different levels of matrix development. Furthermore, MR outcomes are nonspecific, with particular changes in matrix components resulting in changes in multiple MR parameters. To address these limitations, we present two new approaches for the evaluation of tissue engineered constructs using MR, and apply them to immature and mature engineered cartilage after 1 and 5 weeks of development, respectively. First, we applied multiexponential T(2) analysis for the quantification of matrix macromolecule-associated water compartments. Second, we applied multivariate support vector machine analysis using multiple MR parameters to improve detection of degree of matrix development. Monoexponential T(2) values decreased with maturation, but without further specificity. Much more specific information was provided by multiexponential analysis. The T(2) distribution in both immature and mature constructs was qualitatively comparable to that of native cartilage. The analysis showed that proteoglycan-bound water increased significantly during maturation, from a fraction of 0.05 ± 0.01 to 0.07 ± 0.01. Classification of samples based on individual MR parameters, T(1), T(2), k(m) or apparent diffusion coefficient, showed that the best classifiers were T(1) and k(m), with classification accuracies of 85% and 84%, respectively. Support vector machine analysis improved the accuracy to 98% using the combination (k(m), apparent diffusion coefficient). These approaches were validated using biochemical and Fourier transform infrared imaging spectroscopic analyses, which showed increased proteoglycan and collagen with maturation. In summary, multiexponential T(2) and multivariate support vector machine analyses provide improved sensitivity to changes in matrix development and specificity to matrix composition in tissue engineered cartilage. These approaches show substantial potential for the evaluation of engineered cartilage tissue and for extension to other tissue engineering constructs.
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Affiliation(s)
- David A Reiter
- Clinical Research Branch, National Institute on Aging, National Institutes of Health, Baltimore, MD 21225, USA.
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12
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Irrechukwu ON, Reiter DA, Lin PC, Roque RA, Fishbein KW, Spencer RG. Characterization of engineered cartilage constructs using multiexponential T₂ relaxation analysis and support vector regression. Tissue Eng Part C Methods 2012; 18:433-43. [PMID: 22166112 DOI: 10.1089/ten.tec.2011.0509] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
Abstract
Increased sensitivity in the characterization of cartilage matrix status by magnetic resonance (MR) imaging, through the identification of surrogate markers for tissue quality, would be of great use in the noninvasive evaluation of engineered cartilage. Recent advances in MR evaluation of cartilage include multiexponential and multiparametric analysis, which we now extend to engineered cartilage. We studied constructs which developed from chondrocytes seeded in collagen hydrogels. MR measurements of transverse relaxation times were performed on samples after 1, 2, 3, and 4 weeks of development. Corresponding biochemical measurements of sulfated glycosaminoglycan (sGAG) were also performed. sGAG per wet weight increased from 7.74±1.34 μg/mg in week 1 to 21.06±4.14 μg/mg in week 4. Using multiexponential T₂ analysis, we detected at least three distinct water compartments, with T₂ values and weight fractions of (45 ms, 3%), (200 ms, 4%), and (500 ms, 97%), respectively. These values are consistent with known properties of engineered cartilage and previous studies of native cartilage. Correlations between sGAG and MR measurements were examined using conventional univariate analysis with T₂ data from monoexponential fits with individual multiexponential compartment fractions and sums of these fractions, through multiple linear regression based on linear combinations of fractions, and, finally, with multivariate analysis using the support vector regression (SVR) formalism. The phenomenological relationship between T₂ from monoexponential fitting and sGAG exhibited a correlation coefficient of r²=0.56, comparable to the more physically motivated correlations between individual fractions or sums of fractions and sGAG; the correlation based on the sum of the two proteoglycan-associated fractions was r²=0.58. Correlations between measured sGAG and those calculated using standard linear regression were more modest, with r² in the range 0.43-0.54. However, correlations using SVR exhibited r² values in the range 0.68-0.93. These results indicate that the SVR-based multivariate approach was able to determine tissue sGAG with substantially higher accuracy than conventional monoexponential T₂ measurements or conventional regression modeling based on water fractions. This combined technique, in which the results of multiexponential analysis are examined with multivariate statistical techniques, holds the potential to greatly improve the accuracy of cartilage matrix characterization in engineered constructs using noninvasive MR data.
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Affiliation(s)
- Onyi N Irrechukwu
- Magnetic Resonance Imaging and Spectroscopy Section, Gerontology Research Center, National Institute on Aging, National Institutes of Health , Baltimore, Maryland, USA
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Nugent AE, McBurney DL, Horton WE. The presence of extracellular matrix alters the chondrocyte response to endoplasmic reticulum stress. J Cell Biochem 2011; 112:1118-29. [DOI: 10.1002/jcb.23025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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14
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Irrechukwu ON, Lin PC, Fritton K, Doty S, Pleshko N, Spencer RG. Magnetic resonance studies of macromolecular content in engineered cartilage treated with pulsed low-intensity ultrasound. Tissue Eng Part A 2010; 17:407-15. [PMID: 20807015 DOI: 10.1089/ten.tea.2010.0187] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Noninvasive monitoring of matrix development in tissue-engineered cartilage constructs would permit ongoing assessment with the ability to modify culture conditions during development to optimize tissue characteristics. In this study, chondrocytes seeded in a collagen hydrogel were exposed for 20 min/day to pulsed low-intensity ultrasound (PLIUS) at 30 mWcm(-2) and cultured for up to 5 weeks. Biochemical assays, histology, immunohistochemistry, Fourier transform infrared spectroscopy, and magnetic resonance imaging (MRI) were performed at weeks 3 and 5 after initiation of growth. The noninvasive MRI measurements were correlated with those from the invasive studies. In particular, MRI transverse relaxation time (T2) and magnetization transfer rate (k(m)) correlated with macromolecular content, which was increased by application of PLIUS. This indicates the sensitivity of MR techniques to PLIUS-induced changes in matrix development, and highlights the potential for noninvasive assessment of the efficacy of anabolic interventions for engineered tissue.
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Affiliation(s)
- Onyi N Irrechukwu
- Magnetic Resonance Imaging and Spectroscopy Section, Gerontology Research Center 4D-06, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
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