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She Y, Sun Y, Jiang N. The mechanics of tissue-engineered temporomandibular joint discs: Current status and prospects for enhancement. J Biomater Appl 2024; 39:269-287. [PMID: 39023922 DOI: 10.1177/08853282241265059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
The temporomandibular joint (TMJ) disc is an essential protective but vulnerable fibrocartilage. Their high mechanical strength is vital in absorbing loads, reducing friction, and protecting the condylar surface. Many diseases can lead to the destruction or degeneration of the mechanical function of the TMJ disc. Unfortunately, conservative treatment is ineffective in restoring the defective mechanical properties of the discs. Tissue engineering has been investigated as a promising alternative treatment approach to approximate the properties of native tissue. However, it is difficult for tissue-engineered discs to obtain sufficient mechanical properties. Several approaches have been proposed to improve the mechanical properties of tissue-engineered constructs. In this review, we summarized the mechanical properties of native TMJ discs and discussed the current mechanical testing methods. We then summarized the current advances in improving the mechanical properties of TMJ disc tissue-engineered constructs. Moreover, existing challenges and outbreak directions are discussed. This review assists future research in better understanding the mechanical properties of both native and tissue-engineered TMJ discs. It provides new insights into future mechanical property enhancement for TMJ disc tissue engineering.
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Affiliation(s)
- Yilin She
- State Key Laboratory of Oral Diseases, and National Clinical Research Center for Oral Disease, and West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yixin Sun
- State Key Laboratory of Oral Diseases, and National Clinical Research Center for Oral Disease, and West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Nan Jiang
- State Key Laboratory of Oral Diseases, and National Clinical Research Center for Oral Disease, and West China Hospital of Stomatology, Sichuan University, Chengdu, China
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2
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Buchweitz N, Sun Y, Cisewski Porto S, Kelley J, Niu Y, Wang S, Meng Z, Reitman C, Slate E, Yao H, Wu Y. Regional structure-function relationships of lumbar cartilage endplates. J Biomech 2024; 169:112131. [PMID: 38739987 PMCID: PMC11182561 DOI: 10.1016/j.jbiomech.2024.112131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 04/17/2024] [Accepted: 05/02/2024] [Indexed: 05/16/2024]
Abstract
Cartilage endplates (CEPs) act as protective mechanical barriers for intervertebral discs (IVDs), yet their heterogeneous structure-function relationships are poorly understood. This study addressed this gap by characterizing and correlating the regional biphasic mechanical properties and biochemical composition of human lumbar CEPs. Samples from central, lateral, anterior, and posterior portions of the disc (n = 8/region) were mechanically tested under confined compression to quantify swelling pressure, equilibrium aggregate modulus, and hydraulic permeability. These properties were correlated with CEP porosity and glycosaminoglycan (s-GAG) content, which were obtained by biochemical assays of the same specimens. Both swelling pressure (142.79 ± 85.89 kPa) and aggregate modulus (1864.10 ± 1240.99 kPa) were found to be regionally dependent (p = 0.0001 and p = 0.0067, respectively) in the CEP and trended lowest in the central location. No significant regional dependence was observed for CEP permeability (1.35 ± 0.97 * 10-16 m4/Ns). Porosity measurements correlated significantly with swelling pressure (r = -0.40, p = 0.0227), aggregate modulus (r = -0.49, p = 0.0046), and permeability (r = 0.36, p = 0.0421), and appeared to be the primary indicator of CEP biphasic mechanical properties. Second harmonic generation microscopy also revealed regional patterns of collagen fiber anchoring, with fibers inserting the CEP perpendicularly in the central region and at off-axial directions in peripheral regions. These results suggest that CEP tissue has regionally dependent mechanical properties which are likely due to the regional variation in porosity and matrix structure. This work advances our understanding of healthy baseline endplate biomechanics and lays a groundwork for further understanding the role of CEPs in IVD degeneration.
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Affiliation(s)
- Nathan Buchweitz
- Department of Bioengineering, Clemson University, Clemson, SC, USA.
| | - Yi Sun
- Department of Orthopaedics, The 2nd Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Sarah Cisewski Porto
- Department of Bioengineering, Clemson University, Clemson, SC, USA; School of Health Sciences, College of Charleston, Charleston, SC, USA.
| | - Joshua Kelley
- Department of Bioengineering, Clemson University, Clemson, SC, USA.
| | - Yipeng Niu
- College of Art and Science, New York University, New York City, NY, USA.
| | - Shangping Wang
- Department of Bioengineering, Clemson University, Clemson, SC, USA.
| | - Zhaoxu Meng
- Department of Mechanical Engineering, Clemson University, Clemson, SC, USA.
| | - Charles Reitman
- Department of Orthopaedics and Physical Medicine, Medical University of South Carolina, Charleston, SC, USA.
| | - Elizabeth Slate
- Department of Statistics, Florida State University, Tallahassee, FL, USA.
| | - Hai Yao
- Department of Bioengineering, Clemson University, Clemson, SC, USA; Department of Orthopaedics and Physical Medicine, Medical University of South Carolina, Charleston, SC, USA.
| | - Yongren Wu
- Department of Bioengineering, Clemson University, Clemson, SC, USA; Department of Orthopaedics and Physical Medicine, Medical University of South Carolina, Charleston, SC, USA.
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Donahue RP, Kallins EG, Hu JC, Athanasiou KA. Characterization of the Temporomandibular Joint Disc Complex in the Yucatan Minipig. Tissue Eng Part A 2023; 29:439-448. [PMID: 37073459 PMCID: PMC10440658 DOI: 10.1089/ten.tea.2023.0011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 04/17/2023] [Indexed: 04/20/2023] Open
Abstract
The temporomandibular joint (TMJ) disc complex (i.e., the TMJ disc and its six attachments) is crucial to everyday functions such as mastication and speaking. The TMJ can be afflicted by many conditions, including disc displacement and defects. Pathologies of the TMJ disc complex most commonly present first as anterior disc displacement, which the field hypothesizes may implicate the two posterior attachments. As a result of anterior disc displacement, defects may develop in the lateral disc complex. Tissue engineering is poised to improve treatment paradigms for these indications of the TMJ disc complex by engineering biomimetic implants, but, first, gold-standard design criteria for such implants should be established through characterization studies. This study's objective was to characterize the structural, mechanical, biochemical, and crosslinking differences among the two posterior attachments and the lateral disc in the Yucatan minipig, a well-accepted TMJ animal model. In tension, it was found that the posterior inferior attachment (PIA) was significantly stiffer and stronger by 2.13 and 2.30 times, respectively, than the posterior superior attachment (PSA). It was found that collagen in both attachments was primarily aligned mediolaterally; however, the lateral disc was much more aligned and anisotropic than either attachment. Among the three locations, the PSA exhibited the greatest degree of heterogeneity and highest proportion of fat vacuoles. The PIA and lateral disc were 1.93 and 1.91 times more collagenous, respectively, by dry weight (DW) than the PSA. The PIA also exhibited 1.78 times higher crosslinking per DW than the PSA. Glycosaminoglycan per DW was significantly higher in the lateral disc by 1.48 and 5.39 times than the PIA and PSA, respectively. Together, these results establish design criteria for tissue-engineering of the TMJ disc complex and indicate that the attachments are less fibrocartilaginous than the disc, while still significantly contributing to the mechanical stability of the TMJ disc complex during articulation. These results also support the biomechanical function of the PIA and PSA, suggesting that the stiffer PIA anchors the disc to the mandibular condyle during articulation, while the softer PSA serves to allow translation over the articular eminence. Impact Statement Characterization of the temporomandibular joint (TMJ) disc complex (i.e., the disc and its attachments) has important implications for those aiming to tissue-engineer functional replacements and can help elucidate its biomechanical function. For example, the findings shown here suggest that the stiffer posterior inferior attachment anchors the disc during articulation, while the softer posterior superior attachment allows translation over the articular eminence.
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Affiliation(s)
- Ryan P. Donahue
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California, USA
| | - Eston G. Kallins
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California, USA
| | - Jerry C. Hu
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California, USA
| | - Kyriacos A. Athanasiou
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California, USA
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Bielajew BJ, Donahue RP, Espinosa MG, Arzi B, Wang D, Hatcher DC, Paschos NK, Wong MEK, Hu JC, Athanasiou KA. Knee orthopedics as a template for the temporomandibular joint. Cell Rep Med 2021; 2:100241. [PMID: 34095872 PMCID: PMC8149366 DOI: 10.1016/j.xcrm.2021.100241] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Although the knee joint and temporomandibular joint (TMJ) experience similar incidence of cartilage ailments, the knee orthopedics field has greater funding and more effective end-stage treatment options. Translational research has resulted in the development of tissue-engineered products for knee cartilage repair, but the same is not true for TMJ cartilages. Here, we examine the anatomy and pathology of the joints, compare current treatments and products for cartilage afflictions, and explore ways to accelerate the TMJ field. We examine disparities, such as a 6-fold higher article count and 2,000-fold higher total joint replacement frequency in the knee compared to the TMJ, despite similarities in osteoarthritis incidence. Using knee orthopedics as a template, basic and translational research will drive the development and implementation of clinical products for the TMJ. With more funding opportunities, training programs, and federal guidance, millions of people afflicted with TMJ disorders could benefit from novel, life-changing therapeutics.
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Affiliation(s)
- Benjamin J Bielajew
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, USA
| | - Ryan P Donahue
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, USA
| | - M Gabriela Espinosa
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, USA
| | - Boaz Arzi
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA
| | - Dean Wang
- Department of Orthopaedic Surgery, University of California, Irvine Medical Center, Orange, CA, USA
| | | | - Nikolaos K Paschos
- Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Mark E K Wong
- Department of Oral and Maxillofacial Surgery, University of Texas School of Dentistry, Houston, TX, USA
| | - Jerry C Hu
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, USA
| | - Kyriacos A Athanasiou
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, USA
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Quinlan ND, Wu Y, Chiaramonti AM, Guess S, Barfield WR, Yao H, Pellegrini VD. Functional Flexion Instability After Rotating-Platform Total Knee Arthroplasty. J Bone Joint Surg Am 2020; 102:1694-1702. [PMID: 33027123 DOI: 10.2106/jbjs.19.01403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND We sought to define "at risk" loading conditions associated with rotating-platform total knee arthroplasty (TKA-RP) implants that predispose to insert subluxation and spinout and to quantify tolerances for flexion-extension gap asymmetry and laxity in order to prevent these adverse events. METHODS Biomechanical testing was performed on 6 fresh-frozen cadaveric limbs with a TKA-RP implant with use of a gap-balancing technique, followed by sequential femoral component revision with variable-thickness polyethylene inserts to systematically represent 5 flexion-extension mismatch and asymmetry conditions. Each configuration was subjected to mechanical loading at 0°, 30°, and 60°. Rotational displacement of the insert on the tibial baseplate, lateral compartment separation, and insert concavity depth were measured with use of a digital caliper. Yield torque, a surrogate for ease of insert rotation and escape of the femoral component, was calculated with use of custom MATLAB code. RESULTS Design-intended insert rotation decreased with increasing knee flexion angles in each loading configuration. Likewise, yield torque increased with increasing joint flexion and decreased with increasing joint laxity in all testing configurations. Insert instability and femoral condyle displacement were reproduced in positions of increasing knee flexion and asymmetrical flexion gap laxity. The depth of lateral polyethylene insert concavity determined femoral condylar capture and defined a narrow tolerance of <2 mm in the smallest implant sizes for flexion gap asymmetry leading to rotational insert instability. CONCLUSIONS Decreased femoral-tibial articular surface conformity with increasing knee flexion and asymmetrical flexion gap laxity enable paradoxical motion of the femoral component on the upper insert surface rather than the undersurface, as designed. CLINICAL RELEVANCE Mobile-bearing TKA-RP is a technically demanding procedure requiring a snug symmetrical flexion gap. As little as 2 mm of asymmetrical lateral flexion laxity can result in decreased conformity, condyle liftoff, and insert subluxation. Flexion beyond 30° decreases bearing surface contact area and predisposes to reduced insert rotation and mechanical malfunction.
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Affiliation(s)
- Nicole Durig Quinlan
- Department of Orthopaedic Surgery, University of Virginia Health System, Charlottesville, Virginia
- Department of Orthopaedics and Physical Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Yongren Wu
- Department of Orthopaedics and Physical Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Alexander M Chiaramonti
- Department of Orthopaedics and Physical Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Sarah Guess
- Department of Orthopaedics and Physical Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - William R Barfield
- Department of Orthopaedics and Physical Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Hai Yao
- Department of Orthopaedics and Physical Medicine, Medical University of South Carolina, Charleston, South Carolina
- Department of Bioengineering, Clemson University, Clemson-MUSC Bioengineering Program, Charleston, South Carolina
| | - Vincent D Pellegrini
- Department of Orthopaedics and Physical Medicine, Medical University of South Carolina, Charleston, South Carolina
- Department of Bioengineering, Clemson University, Clemson-MUSC Bioengineering Program, Charleston, South Carolina
- Department of Orthopaedics, Dartmouth-Hitchcock Medical Center, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire
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Barrientos E, Pelayo F, Tanaka E, Lamela-Rey MJ, Fernández-Canteli A. Viscoelastic properties of the central region of porcine temporomandibular joint disc in shear stress-relaxation. J Biomech 2019; 93:126-131. [PMID: 31301763 DOI: 10.1016/j.jbiomech.2019.06.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 06/14/2019] [Accepted: 06/23/2019] [Indexed: 11/28/2022]
Abstract
In this study, shear relaxation properties of the porcine temporomandibular joint (TMJ) disc are investigated. Previous studies have shown that, in fatigue failure and damage of cartilage and fibrocartilage, shear loads could be one of the biggest contributors to the failure. The aim of the present study is to develop an evaluation method to study shear properties of the disc and to do a mathematical characterization of it. For the experiments, twelve porcine discs were used. Each disc was dissected from the TMJ and, then, static strain control tests were carried out to obtain the shear relaxation modulus for the central region of the discs. From the results, it was found that the disc presents a viscoelastic behavior under shear loads. Relaxation modulus decreased with time. Shear relaxation was 10% of the instantaneous stress, which implies that the viscous properties of the disc cannot be neglected. The present results lead to a better understanding of the discs mechanical behavior under realistic TMJ working conditions.
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Affiliation(s)
- Eva Barrientos
- Department of Construction and Manufacturing Engineering, University of Oviedo, Gijón, Spain.
| | - Fernandez Pelayo
- Department of Construction and Manufacturing Engineering, University of Oviedo, Gijón, Spain
| | - Eiji Tanaka
- Department of Orthodontics and Dentofacial Orthopedics, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - María Jesús Lamela-Rey
- Department of Construction and Manufacturing Engineering, University of Oviedo, Gijón, Spain
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7
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Fazaeli S, Ghazanfari S, Mirahmadi F, Everts V, Smit TH, Koolstra JH. The dynamic mechanical viscoelastic properties of the temporomandibular joint disc: The role of collagen and elastin fibers from a perspective of polymer dynamics. J Mech Behav Biomed Mater 2019; 100:103406. [PMID: 31473438 DOI: 10.1016/j.jmbbm.2019.103406] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 07/27/2019] [Accepted: 08/24/2019] [Indexed: 10/26/2022]
Abstract
The temporomandibular joint disc is a structure, characterized as heterogeneous fibrocartilage, and is composed of macromolecular biopolymers. Despite a large body of characterization studies, the contribution of matrix biopolymers on the dynamic viscoelastic behavior of the disc is poorly understood. Given the high permeability and low concentration of glycosaminoglycans in the disc, it has been suggested that poro-elastic behavior can be neglected and that the intrinsic viscoelastic nature of solid matrix plays a dominant role in governing its time-dependent behavior. This study attempts to quantify the contribution of collagen and elastin fibers to the viscoelastic properties of the disc. Using collagenase and elastase, we perturbed the collagen and elastin fibrillar network in porcine temporomandibular joint discs and investigated the changes of dynamic viscoelastic properties in five different regions of the disc. Following both treatments, the storage and loss moduli of these regions were reduced dramatically up to the point that the tissue was no longer mechanically heterogeneous. However, the proportion of changes in storage and loss moduli were different for each treatment, reflected in the decrease and increase of the loss tangent for collagenase and elastase treated discs, respectively. The reduction of storage and loss moduli of the disc correlated with a decrease of biopolymer length. The present study indicates that the compositional and structural changes of collagen and elastin fibers alter the viscoelastic properties of the disc consistent with polymer dynamics.
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Affiliation(s)
- Sepanta Fazaeli
- Department of Oral Cell Biology and Functional Anatomy, Academic Centre for Dentistry Amsterdam, University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam, the Netherlands.
| | - Samaneh Ghazanfari
- Aachen-Maastricht Institute for Biobased Materials, Faculty of Science and Engineering, Maastricht University, Geleen, the Netherlands; Department of Biohybrid & Medical Textiles (Biotex), RWTH Aachen University, Aachen, Germany.
| | - Fereshteh Mirahmadi
- Department of Oral Cell Biology and Functional Anatomy, Academic Centre for Dentistry Amsterdam, University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam, the Netherlands.
| | - Vincent Everts
- Department of Oral Cell Biology and Functional Anatomy, Academic Centre for Dentistry Amsterdam, University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam, the Netherlands.
| | - Theodoor Henri Smit
- Department of Medical Biology - Academic Medical Center Amsterdam, Amsterdam, the Netherlands.
| | - Jan Harm Koolstra
- Department of Oral Cell Biology and Functional Anatomy, Academic Centre for Dentistry Amsterdam, University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam, the Netherlands.
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Peloquin JM, Santare MH, Elliott DM. Short cracks in knee meniscus tissue cause strain concentrations, but do not reduce ultimate stress, in single-cycle uniaxial tension. ROYAL SOCIETY OPEN SCIENCE 2018; 5:181166. [PMID: 30564409 PMCID: PMC6281910 DOI: 10.1098/rsos.181166] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 10/19/2018] [Indexed: 05/15/2023]
Abstract
Tears are central to knee meniscus pathology and, from a mechanical perspective, are crack-like defects (cracks). In many materials, cracks create stress concentrations that cause progressive local rupture and reduce effective strength. It is currently unknown if cracks in meniscus have these consequences; if they do, this would have repercussions for management of meniscus pathology. The objective of this study was to determine if a short crack in meniscus tissue, which mimics a preclinical meniscus tear, (a) causes crack growth and reduces effective strength, (b) creates a near-tip strain concentration and (c) creates unloaded regions on either side of the crack. Specimens with and without cracks were tested in uniaxial tension and compared in terms of macroscopic stress-strain curves and digital image correlation strain fields. The strain fields were used as an indicator of stress concentrations and unloaded regions. Effective strength was found to be insensitive to the presence of a crack (potential effect < 0.86 s.d.; β = 0.2), but significant strain concentrations, which have the potential to lead to long-term accumulation of tissue or cell damage, were observed near the crack tip.
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Affiliation(s)
- John M. Peloquin
- Department of Biomedical Engineering, University of Delaware, Newark, DE, USA
| | - Michael H. Santare
- Department of Mechanical Engineering, University of Delaware, Newark, DE, USA
| | - Dawn M. Elliott
- Department of Biomedical Engineering, University of Delaware, Newark, DE, USA
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Coombs MC, Bonthius DJ, Nie X, Lecholop MK, Steed MB, Yao H. Effect of Measurement Technique on TMJ Mandibular Condyle and Articular Disc Morphometry: CBCT, MRI, and Physical Measurements. J Oral Maxillofac Surg 2018; 77:42-53. [PMID: 30076808 DOI: 10.1016/j.joms.2018.06.175] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 05/28/2018] [Accepted: 06/26/2018] [Indexed: 11/25/2022]
Abstract
PURPOSE Accurate description of the temporomandibular size and shape (morphometry) is critical for clinical diagnosis and surgical planning and the design and development of regenerative scaffolds and prosthetic devices and to model the temporomandibular loading environment. The study objective was to determine the 3-dimensional morphometry of the temporomandibular joint (TMJ) condyle and articular disc using cone-beam computed tomography (CBCT), magnetic resonance imaging (MRI), and physical measurements of the same joints using a repeated measures design and to determine the effect of the measurement technique on temporomandibular size and shape. MATERIALS AND METHODS Human cadaveric heads underwent a multistep protocol to acquire physiologically meaningful measurements of the condyle and disc. The heads first underwent CBCT scanning, and solid models were automatically generated. The superficial soft tissues were dissected, and intact TMJs were excised and underwent MRI scanning, with solid models generated after manual segmentation. After MRI, the intact joints were dissected, and physical measurements of the condyle and articular disc were performed. The CBCT-based model measurements, MRI-based model measurements, and physical measurements were standardized, and a repeated measures study design was used to determine the effect of the measurement technique on the morphometric parameters. RESULTS Multivariate general linear mixed effects models showed significant effects for measurement technique for condylar morphometric outcomes (P < .001) and articular disc morphometric outcomes (P < .001). The physical measurements after dissection were larger than either the CBCT-based or MRI-based measurements. Differences in imaging-based morphometric parameters followed a complex relationship between imaging modality resolution and contrast between tissue types. CONCLUSIONS Physical measurements after dissection are still considered the reference standard. However, owing to their inaccessibility in vivo, understanding how the imaging technique affects the temporomandibular size and shape is critical toward the development of high-fidelity solid models to be used in the design and development of regenerative scaffolds, surgical planning, prosthetic devices, and anatomic investigations.
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Affiliation(s)
- Matthew C Coombs
- Postdoctoral Fellow, Department of Bioengineering, Clemson University, Clemson, SC; and Department of Oral Health Sciences, Medical University of South Carolina, Charleston, SC
| | - Daniel J Bonthius
- MD/PhD Student, Department of Bioengineering, Clemson University, Clemson, SC
| | - Xingju Nie
- Research Associate, Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC
| | - Michael K Lecholop
- Assistant Professor, Department of Oral and Maxillofacial Surgery, Medical University of South Carolina, Charleston, SC
| | - Martin B Steed
- Professor and Department Head, Department of Oral and Maxillofacial Surgery, Medical University of South Carolina, Charleston, SC
| | - Hai Yao
- Professor, Department of Bioengineering, Clemson University, Clemson, SC; and Department of Oral Health Sciences, Medical University of South Carolina, Charleston, SC.
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Effect of freezing storage time on the elastic and viscous properties of the porcine TMJ disc. J Mech Behav Biomed Mater 2017; 71:314-319. [DOI: 10.1016/j.jmbbm.2017.03.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 03/21/2017] [Accepted: 03/31/2017] [Indexed: 11/17/2022]
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Wu Y, Cisewski SE, Wei F, She X, Gonzales TS, Iwasaki LR, Nickel JC, Yao H. Fluid pressurization and tractional forces during TMJ disc loading: A biphasic finite element analysis. Orthod Craniofac Res 2017; 20 Suppl 1:151-156. [PMID: 28643926 PMCID: PMC5928793 DOI: 10.1111/ocr.12147] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/26/2017] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To investigate the ploughing mechanism associated with tractional force formation on the temporomandibular joint (TMJ) disc surface. SETTING AND SAMPLE POPULATION Ten left TMJ discs were harvested from 6- to 8-month-old male Yorkshire pigs. MATERIALS AND METHODS Confined compression tests characterized mechanical TMJ disc properties, which were incorporated into a biphasic finite element model (FEM). The FEM was established to investigate load carriage within the extracellular matrix (ECM) and the ploughing mechanism during tractional force formation by simulating previous in vitro plough experiments. RESULTS Biphasic mechanical properties were determined in five TMJ disc regions (average±standard deviation for aggregate modulus: 0.077±0.040 MPa; hydraulic permeability: 0.88±0.37×10-3 mm4 /Ns). FE simulation results demonstrated that interstitial fluid pressurization is a dominant loading support mechanism in the TMJ disc. Increased contact load and duration led to increased solid ECM strain and stress within, and increased ploughing force on the surface of the disc. CONCLUSION Sustained mechanical loading may play a role in load carriage within the ECM and ploughing force formation during stress-field translation at the condyle-disc interface. This study further elucidated the mechanism of ploughing on tractional force formation and provided a baseline for future analysis of TMJ mechanics, cartilage fatigue and early TMJ degeneration.
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Affiliation(s)
- Y. Wu
- Department of Bioengineering, Clemson University, Clemson, SC, USA
- Department of Orthopaedics, Medical University of South Carolina (MUSC), Charleston, SC, USA
| | - S. E. Cisewski
- Department of Bioengineering, Clemson University, Clemson, SC, USA
| | - F. Wei
- Department of Bioengineering, Clemson University, Clemson, SC, USA
| | - X. She
- Department of Bioengineering, Clemson University, Clemson, SC, USA
| | - T. S. Gonzales
- Department of Oral Health Sciences, MUSC, Charleston, SC, USA
| | - L. R. Iwasaki
- Department of Orthodontics and Dentofacial Orthopaedics, University of Missouri-Kansas City, Kansas City, MO, USA
| | - J. C. Nickel
- Department of Orthodontics and Dentofacial Orthopaedics, University of Missouri-Kansas City, Kansas City, MO, USA
| | - H. Yao
- Department of Bioengineering, Clemson University, Clemson, SC, USA
- Department of Orthopaedics, Medical University of South Carolina (MUSC), Charleston, SC, USA
- Department of Oral Health Sciences, MUSC, Charleston, SC, USA
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12
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Wu Y, Kuo J, Wright GJ, Cisewski SE, Wei F, Kern MJ, Yao H. Viscoelastic shear properties of porcine temporomandibular joint disc. Orthod Craniofac Res 2016; 18 Suppl 1:156-63. [PMID: 25865544 DOI: 10.1111/ocr.12088] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2014] [Indexed: 12/01/2022]
Abstract
OBJECTIVES To investigate the intrinsic viscoelastic shear properties in porcine TMJ discs. MATERIALS AND METHODS Twelve fresh porcine TMJ discs from young adult pigs (6-8 months) were used. Cylindrical samples (5 mm diameter) with uniform thickness (~1.2 mm) were prepared from five regions of the TMJ disc. Torsional shear tests were performed under 10% compressive strain. Dynamic shear was applied in two methods: 1) a frequency sweep test over the frequency range of 0.1-10 rad/s with a constant shear strain amplitude of 0.05 rad and 2) a strain sweep test over the range of 0.005-0.15 rad at a constant frequency of 10 rad/s. Transient stress relaxation tests were also performed to determine the equilibrium shear properties. RESULTS As the frequency increased in the frequency sweep test, the dynamic shear complex modulus increased, with values ranging from 7 to 17 kPa. The phase angle, ranging from 11 to 15 degrees, displayed no pattern of regional variation as the frequency increased. The dynamic shear modulus decreased as the shear strain increased. The equilibrium shear modulus had values ranging from 2.6 to 4 kPa. The posterior region had significantly higher values for dynamic shear modulus than those in the anterior region, while no significant regional difference was found for equilibrium shear modulus. CONCLUSION Our results suggest that the intrinsic region-dependent viscoelastic shear characteristics of TMJ disc may play a crucial role in determining the local strain of the TMJ disc under mechanical loading.
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Affiliation(s)
- Y Wu
- Department of Bioengineering, Clemson University, Clemson, SC, USA
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13
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Fazaeli S, Ghazanfari S, Everts V, Smit TH, Koolstra JH. The contribution of collagen fibers to the mechanical compressive properties of the temporomandibular joint disc. Osteoarthritis Cartilage 2016; 24:1292-301. [PMID: 26828357 DOI: 10.1016/j.joca.2016.01.138] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 01/06/2016] [Accepted: 01/19/2016] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The Temporomandibular Joint (TMJ) disc is a fibrocartilaginous structure located between the mandibular condyle and the temporal bone, facilitating smooth movements of the jaw. The load-bearing properties of its anisotropic collagenous network have been well characterized under tensile loading conditions. However, recently it has also been speculated that the collagen fibers may contribute dominantly in reinforcing the disc under compression. Therefore, in this study, the structural-functional role of collagen fibers in mechanical compressive properties of TMJ disc was investigated. DESIGN Intact porcine TMJ discs were enzymatically digested with collagenase to disrupt the collagenous network of the cartilage. The digested and non-digested articular discs were analyzed mechanically, biochemically and histologically in five various regions. These tests included: (1) cyclic compression tests, (2) biochemical quantification of collagen and glycosaminoglycan (GAG) content and (3) visualization of collagen fibers' alignment by polarized light microscopy (PLM). RESULTS The instantaneous compressive moduli of the articular discs were reduced by as much as 50-90% depending on the region after the collagenase treatment. The energy dissipation properties of the digested discs showed a similar tendency. Biochemical analysis of the digested samples demonstrated an average of 14% and 35% loss in collagen and GAG, respectively. Despite the low reduction of collagen content the PLM images showed considerable perturbation of the collagenous network of the TMJ disc. CONCLUSIONS The results indicated that even mild disruption of collagen fibers can lead to substantial mechanical softening of TMJ disc undermining its reinforcement and mechanical stability under compression.
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Affiliation(s)
- S Fazaeli
- Department of Oral Cell Biology and Functional Anatomy - Academic Center for Dentistry Amsterdam, University of Amsterdam and VU University Amsterdam, Amsterdam, The Netherlands; MOVE Research Institute Amsterdam, The Netherlands.
| | - S Ghazanfari
- Department of Orthopaedic Surgery - VUmc, Amsterdam, The Netherlands; MOVE Research Institute Amsterdam, The Netherlands.
| | - V Everts
- Department of Oral Cell Biology and Functional Anatomy - Academic Center for Dentistry Amsterdam, University of Amsterdam and VU University Amsterdam, Amsterdam, The Netherlands; MOVE Research Institute Amsterdam, The Netherlands.
| | - T H Smit
- Department of Orthopaedic Surgery - VUmc, Amsterdam, The Netherlands; MOVE Research Institute Amsterdam, The Netherlands.
| | - J H Koolstra
- Department of Oral Cell Biology and Functional Anatomy - Academic Center for Dentistry Amsterdam, University of Amsterdam and VU University Amsterdam, Amsterdam, The Netherlands; MOVE Research Institute Amsterdam, The Netherlands.
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Matuska AM, Muller S, Dolwick MF, McFetridge PS. Biomechanical and biochemical outcomes of porcine temporomandibular joint disc deformation. Arch Oral Biol 2016; 64:72-9. [PMID: 26774186 DOI: 10.1016/j.archoralbio.2016.01.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 11/24/2015] [Accepted: 01/06/2016] [Indexed: 11/15/2022]
Abstract
OBJECTIVE The structure-function relationship in the healthy temporomandibular joint (TMJ) disc has been well established, however the changes in dysfunctional joints has yet to be systematically evaluated. Due to the poor understanding of the etiology of temporomandibular disorders (TMDs) this study evaluated naturally occurring degenerative remodeling in aged female porcine temporomandibular joint (TMJ) discs in order to gain insight into the progression and effects on possible treatment strategies of TMDs. DESIGN Surface and regional biomechanical and biochemical properties of discal tissues were determined in grossly deformed (≥Wilkes Stage 3) and morphologically normal (≤Wilkes Stage 2) TMJ discs. RESULTS Compared to normal disc structure the deformed discs lacked a smooth biconcave shape and characteristic ECM organization. Reduction in tensile biomechanical integrity and increased compressive stiffness and cellularity was found in deformed discs. Regionally, the posterior and intermediate zones of the disc were most frequently affected along with the inferior surface. CONCLUSIONS The frequency of degeneration observed on the inferior surface of the disc (predominantly posterior), suggests that a disruption in the disc-condyle relationship likely contributes to the progression of joint dysfunction more than the temporodiscal relationship. As such, the inferior joint space may be an important consideration in early clinical diagnosis and treatment of TMDs, as it is overlooked in techniques performed in the upper joint space, including arthroscopy and arthrocentesis. Furthermore, permanent damage to the disc mechanical properties would limit the ability to successfully reposition deformed discs, highlighting the importance of emerging therapies such as tissue engineering.
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Affiliation(s)
- Andrea M Matuska
- J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, United States
| | - Stephen Muller
- J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, United States
| | - M Franklin Dolwick
- Department of Oral and Maxillofacial Surgery, University of Florida, United States
| | - Peter S McFetridge
- J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, United States.
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15
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Lakes EH, Kline CL, McFetridge PS, Allen KD. Comparing the mechanical properties of the porcine knee meniscus when hydrated in saline versus synovial fluid. J Biomech 2015; 48:4333-8. [DOI: 10.1016/j.jbiomech.2015.10.046] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 10/30/2015] [Accepted: 10/31/2015] [Indexed: 11/30/2022]
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16
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MacBarb RF, Paschos NK, Abeug R, Makris EA, Hu JC, Athanasiou KA. Passive strain-induced matrix synthesis and organization in shape-specific, cartilaginous neotissues. Tissue Eng Part A 2015; 20:3290-302. [PMID: 24918268 DOI: 10.1089/ten.tea.2013.0694] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Tissue-engineered musculoskeletal soft tissues typically lack the appropriate mechanical robustness of their native counterparts, hindering their clinical applicability. With structure and function being intimately linked, efforts to capture the anatomical shape and matrix organization of native tissues are imperative to engineer functionally robust and anisotropic tissues capable of withstanding the biomechanically complex in vivo joint environment. The present study sought to tailor the use of passive axial compressive loading to drive matrix synthesis and reorganization within self-assembled, shape-specific fibrocartilaginous constructs, with the goal of developing functionally anisotropic neotissues. Specifically, shape-specific fibrocartilaginous neotissues were subjected to 0, 0.01, 0.05, or 0.1 N axial loads early during tissue culture. Results found the 0.1-N load to significantly increase both collagen and glycosaminoglycan synthesis by 27% and 67%, respectively, and to concurrently reorganize the matrix by promoting greater matrix alignment, compaction, and collagen crosslinking compared with all other loading levels. These structural enhancements translated into improved functional properties, with the 0.1-N load significantly increasing both the relaxation modulus and Young's modulus by 96% and 255%, respectively, over controls. Finite element analysis further revealed the 0.1-N uniaxial load to induce multiaxial tensile and compressive strain gradients within the shape-specific neotissues, with maxima of 10.1%, 18.3%, and -21.8% in the XX-, YY-, and ZZ-directions, respectively. This indicates that strains created in different directions in response to a single axis load drove the observed anisotropic functional properties. Together, results of this study suggest that strain thresholds exist within each axis to promote matrix synthesis, alignment, and compaction within the shape-specific neotissues. Tailoring of passive axial loading, thus, presents as a simple, yet effective way to drive in vitro matrix development in shape-specific neotissues toward more closely achieving native structural and functional properties.
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Affiliation(s)
- Regina F MacBarb
- 1 Department of Biomedical Engineering, University of California , Davis, Davis, California
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17
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McDonald M, Vapniarsky-Arzi N, Verstraete F, Staszyk C, Leale D, Woolard K, Arzi B. Characterization of the temporomandibular joint of the harbour porpoise (Phocoena phocoena) and Risso's dolphin (Grampus griseus). Arch Oral Biol 2015; 60:582-92. [DOI: 10.1016/j.archoralbio.2015.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 12/22/2014] [Accepted: 01/02/2015] [Indexed: 10/24/2022]
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18
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Henderson SE, Lowe JR, Tudares MA, Gold MS, Almarza AJ. Temporomandibular joint fibrocartilage degeneration from unilateral dental splints. Arch Oral Biol 2014; 60:1-11. [PMID: 25247778 DOI: 10.1016/j.archoralbio.2014.08.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 08/15/2014] [Accepted: 08/30/2014] [Indexed: 12/31/2022]
Abstract
OBJECTIVE The objective of this study was to determine the extent to which altered loading in the temporomandibular joint (TMJ), as might be associated with a malocclusion, drives degeneration of articulating surfaces in the TMJ. We therefore sought to quantify the effects of altered joint loading on the mechanical properties and biochemical content and distribution of TMJ fibrocartilage in the rabbit. DESIGN Altered TMJ loading was induced with a 1mm splint placed unilaterally over the maxillary and mandibular molars for 6 weeks. At that time, TMJ fibrocartilage was assessed by compression testing, biochemical content (collagen, glycosaminoglycan (GAG), DNA) and distribution (histology), for both the TMJ disc and the condylar fibrocartilage. RESULTS There were no changes in the TMJ disc for any of the parameters tested. The condylar fibrocartilage from the splinted animals was significantly stiffer and the DNA content was significantly lower than that in control animals. There was significant remodeling in the condylar fibrocartilage layers as manifested by a change in GAG and collagen II distribution and a loss of defined cell layers. CONCLUSIONS A connection between the compressive properties of TMJ condylar fibrocartilage after 6 weeks of splinting and the changes in histology was observed. These results suggest a change in joint loading leads to condylar damage, which may contribute to pain associated with at least some forms of TMJ disease.
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Affiliation(s)
- Sarah E Henderson
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jesse R Lowe
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Mauro A Tudares
- Department of Oral Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Michael S Gold
- Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Alejandro J Almarza
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA; Department of Oral Biology, University of Pittsburgh, Pittsburgh, PA, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
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19
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Xiao Y, Rennerfeldt DA, Friis EA, Gehrke SH, Detamore MS. Evaluation of apparent fracture toughness of articular cartilage and hydrogels. J Tissue Eng Regen Med 2014; 11:121-128. [PMID: 24700577 DOI: 10.1002/term.1892] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 12/05/2013] [Accepted: 02/24/2014] [Indexed: 01/24/2023]
Abstract
Recently, biomaterials-based tissue-engineering strategies, including the use of hydrogels, have offered great promise for repairing articular cartilage. Mechanical failure testing in outcome analyses is of crucial clinical importance to the success of engineered constructs. Interpenetrating networks (IPNs) are gaining more attention, due to their superior mechanical integrity. This study provided a combination testing method of apparent fracture toughness, which was applied to both articular cartilage and hydrogels. The apparent fracture toughnesses of two groups, hydrogels and articular cartilage, were evaluated based on the modified single-edge notch test and ASTM standards on the single-edge notch test and compact tension test. The results demonstrated that the toughness for articular cartilage (348 ± 43 MPa/mm½ ) was much higher than that for hydrogels. With a toughness value of 10.8 ± 1.4 MPa/mm½ , IPNs of agarose and poly(ethylene glycol) diacrylate (PEG-DA) looked promising. The IPNs were 1.4 times tougher than PEG-DA alone, although still over an order of magnitude less tough than cartilage. A new method was developed to evaluate hydrogels and cartilage in a manner that enabled a more relevant direct comparison for fracture testing of hydrogels for cartilage tissue engineering. Moreover, a target toughness value for cartilage of using this direct comparison method has been identified (348 ± 43 MPa/mm½ ), and the toughness discrepancy to be overcome between hydrogels and cartilage has been quantified. Copyright © 2014 John Wiley & Sons, Ltd.
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Affiliation(s)
- Yinghua Xiao
- Chemical and Petroleum Engineering, University of Kansas, Lawrence, KS, USA
| | | | | | - Stevin H Gehrke
- Chemical and Petroleum Engineering, University of Kansas, Lawrence, KS, USA
| | - Michael S Detamore
- Chemical and Petroleum Engineering, University of Kansas, Lawrence, KS, USA
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20
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Lomakin J, Sprouse PA, Detamore MS, Gehrke SH. Effect of Pre-Stress on the Dynamic Tensile Behavior of the TMJ Disc. J Biomech Eng 2013; 136:011001. [DOI: 10.1115/1.4025775] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Indexed: 11/08/2022]
Abstract
Previous dynamic analyses of the temporomandibular joint (TMJ) disc have not included a true preload, i.e., a step stress or strain beyond the initial tare load. However, due to the highly nonlinear stress-strain response of the TMJ disc, we hypothesized that the dynamic mechanical properties would greatly depend on the preload, which could then, in part, account for the large variation in the tensile stiffnesses reported for the TMJ disc in the literature. This study is the first to report the dynamic mechanical properties as a function of prestress. As hypothesized, the storage modulus (E′) of the disc varied by a factor of 25 in the mediolateral direction and a factor of 200 in the anteroposterior direction, depending on the prestress. Multiple constant strain rate sweeps were extracted and superimposed via strain-rate frequency superposition (SRFS), which demonstrated that the strain rate amplitude and strain rate were both important factors in determining the TMJ disc material properties, which is an effect not typically seen with synthetic materials. The presented analysis demonstrated, for the first time, the applicability of viscoelastic models, previously applied to synthetic polymer materials, to a complex hierarchical biomaterial such as the TMJ disc, providing a uniquely comprehensive way to capture the viscoelastic response of biological materials. Finally, we emphasize that the use of a preload, preferably which falls within the linear region of the stress-strain curve, is critical to provide reproducible results for tensile analysis of musculoskeletal tissues. Therefore, we recommend that future dynamic mechanical analyses of the TMJ disc be performed at a controlled prestress corresponding to a strain range of 5–10%.
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Affiliation(s)
- J. Lomakin
- Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, KS 66045
| | - P. A. Sprouse
- Bioengineering Program, University of Kansas, 1530 West 15th Street, Lawrence, KS 66045
| | | | - S. H. Gehrke
- e-mail: Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, KS 66045
- Bioengineering Program, University of Kansas, 1530 West 15th Street, Lawrence, KS 66045
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21
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MacBarb RF, Chen AL, Hu JC, Athanasiou KA. Engineering functional anisotropy in fibrocartilage neotissues. Biomaterials 2013; 34:9980-9. [PMID: 24075479 DOI: 10.1016/j.biomaterials.2013.09.026] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Accepted: 09/06/2013] [Indexed: 11/26/2022]
Abstract
The knee meniscus, intervertebral disc, and temporomandibular joint (TMJ) disc all possess complex geometric shapes and anisotropic matrix organization. While these characteristics are imperative for proper tissue function, they are seldom recapitulated following injury or disease. Thus, this study's objective was to engineer fibrocartilages that capture both gross and molecular structural features of native tissues. Self-assembled TMJ discs were selected as the model system, as the disc exhibits a unique biconcave shape and functional anisotropy. To drive anisotropy, 50:50 co-cultures of meniscus cells and articular chondrocytes were grown in biconcave, TMJ-shaped molds and treated with two exogenous stimuli: biomechanical (BM) stimulation via passive axial compression and bioactive agent (BA) stimulation via chondroitinase-ABC and transforming growth factor-β1. BM + BA synergistically increased Col/WW, Young's modulus, and ultimate tensile strength 5.8-fold, 14.7-fold, and 13.8-fold that of controls, respectively; it also promoted collagen fibril alignment akin to native tissue. Finite element analysis found BM stimulation to create direction-dependent strains within the neotissue, suggesting shape plays an essential role toward driving in vitro anisotropic neotissue development. Methods used in this study offer insight on the ability to achieve physiologic anisotropy in biomaterials through the strategic application of spatial, biomechanical, and biochemical cues.
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Affiliation(s)
- Regina F MacBarb
- Department of Biomedical Engineering, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
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22
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MacBarb RF, Makris EA, Hu JC, Athanasiou KA. A chondroitinase-ABC and TGF-β1 treatment regimen for enhancing the mechanical properties of tissue-engineered fibrocartilage. Acta Biomater 2013; 9:4626-34. [PMID: 23041782 DOI: 10.1016/j.actbio.2012.09.037] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 08/24/2012] [Accepted: 09/27/2012] [Indexed: 10/27/2022]
Abstract
The development of functionally equivalent fibrocartilage remains elusive despite efforts to engineer tissues such as knee meniscus, intervertebral disc and temporomandibular joint disc. Attempts to engineer these structures often fail to create tissues with mechanical properties on a par with native tissue, resulting in constructs unsuitable for clinical applications. The objective of this study was to engineer a spectrum of biomimetic fibrocartilages representative of the distinct functional properties found in native tissues. Using the self-assembly process, different co-cultures of meniscus cells and articular chondrocytes were seeded into agarose wells and treated with the catabolic agent chondroitinase-ABC (C-ABC) and the anabolic agent transforming growth factor-β1 (TGF-β1) via a two-factor (cell ratio and bioactive treatment), full factorial study design. Application of both C-ABC and TGF-β1 resulted in a beneficial or positive increase in the collagen content of treated constructs compared to controls. Significant increases in both the collagen density and fiber diameter were also seen with this treatment, increasing these values by 32 and 15%, respectively, over control values. Mechanical testing found the combined bioactive treatment to synergistically increase the Young's modulus and ultimate tensile strength of the engineered fibrocartilages compared to controls, with values reaching the lower spectrum of those found in native tissues. Together, these data demonstrate that C-ABC and TGF-β1 interact to develop a denser collagen matrix better able to withstand tensile loading. This study highlights a way to optimize the tensile properties of engineered fibrocartilage using a biochemical and a biophysical agent together to create distinct fibrocartilages with functional properties mimicking those of native tissue.
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23
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Juran CM, Dolwick MF, McFetridge PS. Shear mechanics of the TMJ disc: relationship to common clinical observations. J Dent Res 2012; 92:193-8. [PMID: 23166043 DOI: 10.1177/0022034512468749] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The temporomandibular joint (TMJ) is a complex hinge and gliding joint that induces significant shear loads onto the fibrocartilage TMJ disc during jaw motion. The purpose of this study was to assess regional variation in the disc's shear loading characteristics under physiologically relevant loads and to associate those mechanical findings with common clinical observations of disc fatigue and damage. Porcine TMJ discs were compressed between an axially translating bottom platen and a 2.5-cm-diameter indenter within a hydrated testing chamber. Discs were cyclically sheared at 0.5, 1, or 5 Hz to 1, 3, or 5% shear strain. Within the anterior and intermediate regions of the disc when sheared in the anteroposterior direction, both shear and compressive moduli experienced a significant decrease from instantaneous to steady state, while the posterior region's compressive modulus decreased approximately 5%, and no significant loss of shear modulus was noted. All regions retained their shear modulus within 0.5% of instantaneous values when shear was applied in the mediolateral direction. The results of the disc's regional shear mechanics suggest an observable and predictable link with the common clinical observation that the posterior region of the disc is most often the zone in which fatigue occurs, which may lead to disc damage and perforation.
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Affiliation(s)
- C M Juran
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611-6131, USA
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24
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Huey DJ, Hu JC, Athanasiou KA. Chondrogenically tuned expansion enhances the cartilaginous matrix-forming capabilities of primary, adult, leporine chondrocytes. Cell Transplant 2012; 22:331-40. [PMID: 23044188 DOI: 10.3727/096368912x657648] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
When expanded through passage, chondrocytes lose their ability to produce high-quality cartilaginous matrix. This study attempts to improve the properties of constructs formed with expanded chondrocytes through alterations in the expansion protocol and the ratio of primary to expanded chondrocytes used to form cartilage constructs. A chondrogenically tuned expansion protocol provided similar monolayer growth rates as those obtained using serum-containing medium and enhanced cartilaginous properties of resultant constructs. Various ratios of primary to chondrogenically expanded chondrocytes were then self-assembled to form neocartilage. Biochemical analysis showed that constructs formed with only expanded cells had twice the GAG per wet weight and collagen II/collagen I ratio compared to constructs formed with primary chondrocytes. Biomechanically, compressive properties of constructs formed with only passaged cells matched the instantaneous modulus and exceeded the relaxation modulus of constructs formed with only primary cells. These counterintuitive results show that, by applying proper expansion and three-dimensional culture techniques, the cartilage-forming potential of adult chondrocytes expanded through passage can be enhanced over that of primary cells.
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Affiliation(s)
- Daniel J Huey
- Department of Biomedical Engineering, University of California-Davis, Davis, CA 95616, USA
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25
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Willard VP, Kalpakci KN, Reimer AJ, Athanasiou KA. The regional contribution of glycosaminoglycans to temporomandibular joint disc compressive properties. J Biomech Eng 2012; 134:011011. [PMID: 22482666 DOI: 10.1115/1.4005763] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Understanding structure-function relationships in the temporomandibular joint (TMJ) disc is a critical first step toward creating functional tissue replacements for the large population of patients suffering from TMJ disc disorders. While many of these relationships have been identified for the collagenous fraction of the disc, this same understanding is lacking for the next most abundant extracellular matrix component, sulfated glycosaminoglycans (GAGs). Though GAGs are known to play a major role in maintaining compressive integrity in GAG-rich tissues such as articular cartilage, their role in fibrocartilaginous tissues in which GAGs are much less abundant is not clearly defined. Therefore, this study investigates the contribution of GAGs to the regional viscoelastic compressive properties of the temporomandibular joint (TMJ) disc. Chondroitinase ABC (C-ABC) was used to deplete GAGs in five different disc regions, and the time course for >95% GAG removal was defined. The compressive properties of GAG depleted regional specimens were then compared to non-treated controls using an unconfined compression stress-relaxation test. Additionally, treated and non-treated specimens were assayed biochemically and histologically to confirm GAG removal. Compared to untreated controls, the only regions affected by GAG removal in terms of biomechanical properties were in the intermediate zone, the most GAG-rich portion of the disc. Without GAGs, all intermediate zone regions showed decreased tissue viscosity, and the intermediate zone lateral region also showed a 12.5% decrease in modulus of relaxation. However, in the anterior and posterior band regions, no change in compressive properties was observed following GAG depletion, though these regions showed the highest compressive properties overall. Although GAGs are not the major extracellular matrix molecule of the TMJ disc, they are responsible for some of the viscoelastic compressive properties of the tissue. Furthermore, the mechanical role of sulfated GAGs in the disc varies regionally in the tissue, and GAG abundance does not always correlate with higher compressive properties. Overall, this study found that sulfated GAGs are important to TMJ disc mechanics in the intermediate zone, an important finding for establishing design characteristics for future tissue engineering efforts.
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Affiliation(s)
- Vincent P Willard
- Department of Bioengineering, Rice University, Houston, TX 77005, USA
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26
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The temporomandibular joint disc of Asian elephant (Elephas maximus) and African elephant (Loxodonta africana). EUR J WILDLIFE RES 2011. [DOI: 10.1007/s10344-011-0595-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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27
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Sanchez-Adams J, Willard VP, Athanasiou KA. Regional variation in the mechanical role of knee meniscus glycosaminoglycans. J Appl Physiol (1985) 2011; 111:1590-6. [PMID: 21903884 DOI: 10.1152/japplphysiol.00848.2011] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
High compressive properties of cartilaginous tissues are commonly attributed to the sulfated glycosaminoglycan (GAG) fraction of the extracellular matrix (ECM), but this relationship has not been directly measured in the knee meniscus, which shows regional variation in GAG content. In this study, biopsies from each meniscus region (outer, middle, and inner) were either subjected to chondroitinase ABC (CABC) to remove all sulfated GAGs or not. Compressive testing revealed that GAG depletion in the inner and middle meniscus regions caused a significant decrease in modulus of relaxation (58% and 41% decreases, respectively, at 20% strain), and all regions exhibited a significant decrease in viscosity (outer: 29%; middle: 58%; inner: 62% decrease). Tensile properties following CABC treatment were unaffected for outer and middle meniscus specimens, but the inner meniscus displayed significant increases in Young's modulus (41% increase) and ultimate tensile stress (40% increase) following GAG depletion. These findings suggest that, in the outer meniscus, GAGs contribute to increasing tissue viscosity, whereas in the middle and inner meniscus, where GAGs are most abundant, these molecules also enhance the tissue's ability to withstand compressive loads. GAGs in the inner meniscus also contribute to reducing the circumferential tensile properties of the tissue, perhaps due to the pre-stress on the collagen network from increased hydration of the ECM. Understanding the mechanical role of GAGs in each region of the knee meniscus is important for understanding meniscus structure-function relationships and creating design criteria for functional meniscus tissue engineering efforts.
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Animal Models of Temporomandibular Joint Disorders: Implications for Tissue Engineering Approaches. Ann Biomed Eng 2011; 39:2479-90. [DOI: 10.1007/s10439-011-0364-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 07/16/2011] [Indexed: 12/19/2022]
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Hagandora CK, Chase TW, Almarza AJ. A comparison of the mechanical properties of the goat temporomandibular joint disc to the mandibular condylar cartilage in unconfined compression. JOURNAL OF DENTAL BIOMECHANICS 2011; 2011:212385. [PMID: 21765875 PMCID: PMC3134092 DOI: 10.4061/2011/212385] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 03/14/2011] [Accepted: 03/24/2011] [Indexed: 11/20/2022]
Abstract
The aim of this study was to make a comparison of the compressive properties of the goat temporomandibular joint (TMJ) disc to the mandibular condylar cartilage (MCC) and to explore the transversely isotropic biphasic model. Samples taken mediolaterally from three regions of the TMJ disc and MCC were tested in unconfined compression at strain levels ranging from 10% to 50% and then assessed for biochemical content. The results indicated that the TMJ disc exhibits a significantly greater tangent modulus than the MCC from 20% to 50% strain with values ranging from 729 ± 267 to 2413 ± 406 kPa and 363 ± 169 to 1677 ± 538 kPa, respectively (P < .05). The collagen content of the TMJ disc was significantly greater than the MCC, while the opposite held for the glycosaminoglycan (GAG) and DNA content. The results emphasize fundamental differences between the articulating tissues of the TMJ.
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Affiliation(s)
- Catherine K Hagandora
- Department of Oral Biology, Department of Bioengineering, Center for Craniofacial Regeneration, McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, 15261, USA
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Kalpakci KN, Kim EJ, Athanasiou KA. Assessment of growth factor treatment on fibrochondrocyte and chondrocyte co-cultures for TMJ fibrocartilage engineering. Acta Biomater 2011; 7:1710-8. [PMID: 21185408 DOI: 10.1016/j.actbio.2010.12.015] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 12/10/2010] [Accepted: 12/17/2010] [Indexed: 11/16/2022]
Abstract
Treatments for patients suffering from severe temporomandibular joint (TMJ) dysfunction are limited, motivating the development of strategies for tissue regeneration. In this study, co-cultures of fibrochondrocytes (FCs) and articular chondrocytes (ACs) were seeded in agarose wells, and supplemented with growth factors, to engineer tissue with biomechanical properties and extracellular matrix composition similar to native TMJ fibrocartilage. In the first phase, growth factors were applied alone and in combination, in the presence or absence of serum, while in the second phase, the best overall treatment was applied at intermittent dosing. Continuous treatment of AC/FC co-cultures with TGF-β1 in serum-free medium resulted in constructs with glycosaminoglycan/wet weight ratios (12.2%), instantaneous compressive moduli (790 kPa), relaxed compressive moduli (120 kPa) and Young's moduli (1.87 MPa) that overlap with native TMJ disc values. Among co-culture groups, TGF-β1 treatment increased collagen deposition ∼20%, compressive stiffness ∼130% and Young's modulus ∼170% relative to controls without growth factor. Serum supplementation, though generally detrimental to functional properties, was identified as a powerful mediator of FC construct morphology. Finally, both intermittent and continuous TGF-β1 treatment showed positive effects, though continuous treatment resulted in greater enhancement of construct functional properties. This work proposes a strategy for regeneration of TMJ fibrocartilage and its future application will be realized through translation of these findings to clinically viable cell sources.
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31
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Kalpakci KN, Willard VP, Wong ME, Athanasiou KA. An interspecies comparison of the temporomandibular joint disc. J Dent Res 2010; 90:193-8. [PMID: 21118792 DOI: 10.1177/0022034510381501] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The temporomandibular joint (TMJ) disc plays a critical role in normal function of the joint, and many disorders of the TMJ are a result of disc dysfunction. Previous quantitative TMJ characterization studies examined either the human or a specific animal model, but no single study has compared different species, in the belief that differences in joint morphology, function, and diet would be reflected in the material properties of the disc. In this study, we examined topographical biochemical (collagen, glycosaminoglycan, and DNA content) and biomechanical (tensile and compressive) properties of the human TMJ disc, and also discs from the cow, goat, pig, and rabbit. Regional and interspecies variations were identified in all parameters measured, and certain disc characteristics were observed across all species, such as a weak intermediate zone under mediolateral tension. While human discs possessed properties distinct from those of the other species, pig discs were most similar to the human, suggesting that the pig may be a suitable animal model for TMJ bioengineering efforts.
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Affiliation(s)
- K N Kalpakci
- Department of Bioengineering, Rice University, Houston, TX 77005, USA
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32
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Gunja NJ, Athanasiou KA. Effects of hydrostatic pressure on leporine meniscus cell-seeded PLLA scaffolds. J Biomed Mater Res A 2010; 92:896-905. [PMID: 19283825 DOI: 10.1002/jbm.a.32451] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Hydrostatic pressure (HP) is an important component of the loading environment of the knee joint. Studies with articular chondrocytes and TMJ disc fibrochondrocytes have identified certain benefits of HP for tissue engineering purposes. However, similar studies with meniscus cells are lacking. Thus, in this experiment, the effects of applying 10 MPa of HP at three different frequencies (0, 0.1, and 1 Hz) to leporine meniscus cell-seeded PLLA scaffolds were examined. HP was applied once every 3 days for 1 h for a period of 28 days. Constructs were analyzed for cellular, biochemical, and biomechanical properties. At t = 4 weeks, total collagen/scaffold was found to be significantly higher in the 10 MPa, 0 Hz group when compared with other groups. This despite the fact that the cell numbers/scaffold were found to be lower in all HP groups when compared with the culture control. Additionally, the total GAG/scaffold, instantaneous modulus, and relaxation modulus were significantly increased in the 10 MPa, 0 Hz group when compared with the culture control. In summary, this experiment provides evidence for the benefit of a 10 MPa, 0 Hz stimulus, on both biochemical and biomechanical aspects, for the purposes of meniscus tissue engineering using PLLA scaffolds.
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Affiliation(s)
- Najmuddin J Gunja
- Department of Bioengineering, Rice University, Houston, Texas 77251, USA
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33
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Kuo J, Zhang L, Bacro T, Yao H. The region-dependent biphasic viscoelastic properties of human temporomandibular joint discs under confined compression. J Biomech 2010; 43:1316-21. [PMID: 20171639 DOI: 10.1016/j.jbiomech.2010.01.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Revised: 01/13/2010] [Accepted: 01/21/2010] [Indexed: 10/19/2022]
Abstract
The objective of this study was to determine the biphasic viscoelastic properties of human temporomandibular joint (TMJ) discs, correlate these properties with disc biochemical composition, and examine the relationship between these properties and disc dynamic behavior in confined compression. The equilibrium aggregate modulus (H(A)), hydraulic permeability (k), and dynamic modulus were examined between five disc regions. Biochemical assays were conducted to quantify the amount of water, collagen, and glycosaminoglycan (GAG) content in each region. The creep tests showed that the average equilibrium moduli of the intermediate, lateral, and medial regions were significantly higher than for the anterior and posterior regions (69.75+/-11.47kPa compared to 22.0+/-5.15kPa). Permeability showed the inverse trend with the largest values in the anterior and posterior regions (8.51+/-1.36x10(-15)m(4)/Ns compared with 3.75+/-0.72x10(-15)m(4)/Ns). Discs were 74.5% water by wet weight, 62% collagen, and 3.2% GAG by dry weight. Regional variations were only observed for water content which likely results in the regional variation in biphasic mechanical properties. The dynamic modulus of samples during confined compression is related to the aggregate modulus and hydraulic permeability of the tissue. The anterior and posterior regions displayed lower complex moduli over all frequencies (0.01-3Hz) with average moduli of 171.8-609.3kPa compared with 454.6-1613.0kPa for the 3 central regions. The region of the TMJ disc with higher aggregate modulus and lower permeability had higher dynamic modulus. Our results suggested that fluid pressurization plays a significant role in the load support of the TMJ disc under dynamic loading conditions.
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Affiliation(s)
- Jonathan Kuo
- Department of Bioengineering, Clemson University, CU-MUSC Bioengineering Program, 173 Ashley Avenue, P.O. Box 250508, Charleston, SC 29425, USA
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34
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Gunja NJ, Athanasiou KA. Additive and synergistic effects of bFGF and hypoxia on leporine meniscus cell-seeded PLLA scaffolds. J Tissue Eng Regen Med 2010; 4:115-22. [PMID: 19937913 PMCID: PMC3553794 DOI: 10.1002/term.221] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Injuries to avascular regions of menisci do not heal and result in significant discomfort to patients. Current treatments, such as partial meniscectomy, alleviate these symptoms in the short term but lead to premature osteoarthritis as a result of compromised stability and changes in knee biomechanics. Thus, tissue engineering of the meniscus may provide an alternative treatment modality to overcome this problem. In this experiment, a scaffold-based tissue-engineering approach was utilized to regenerate the meniscus. Meniscus cells were cultured on poly-L-lactic acid scaffolds in normoxic (approximately 21% oxygen) or hypoxic (approximately 2% oxygen) conditions in the presence or absence of the growth factor, basic fibroblast growth factor (bFGF). At t = 4 weeks, histological sections of constructs showed presence of collagen and glycosaminoglycan (GAG) in all groups. Immunohistochemical staining showed the presence of collagen I in all groups and collagen II in groups cultured under hypoxic conditions. bFGF in the culture medium significantly increased cell number/construct by 25%, regardless of culture conditions. For GAG/construct, synergistic increases were observed in constructs cultured in hypoxic conditions and bFGF (two-fold) when compared to constructs cultured in normoxic conditions. Compressive tests showed synergistic increases in the relaxation modulus and coefficient of viscosity and additive increases in the instantaneous modulus for constructs cultured under hypoxic conditions and bFGF, when compared to constructs cultured under normoxic conditions. Overall, these results demonstrate that bFGF and hypoxia can significantly enhance the ability of meniscus cells to produce GAGs and improve the compressive properties of tissue-engineered meniscus constructs in vitro.
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Affiliation(s)
- Najmuddin J Gunja
- Department of Bioengineering, Rice University, Houston, TX 77251, USA
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35
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Lumpkins SB, McFetridge PS. Regional variations in the viscoelastic compressive properties of the temporomandibular joint disc and implications toward tissue engineering. J Biomed Mater Res A 2009; 90:784-91. [DOI: 10.1002/jbm.a.32148] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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36
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Gunja NJ, Athanasiou KA. Effects of co-cultures of meniscus cells and articular chondrocytes on PLLA scaffolds. Biotechnol Bioeng 2009; 103:808-16. [DOI: 10.1002/bit.22301] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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37
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Singh M, Detamore MS. Stress Relaxation Behavior of Mandibular Condylar Cartilage Under High-Strain Compression. J Biomech Eng 2009; 131:061008. [DOI: 10.1115/1.3118776] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
During temporomandibular joint (TMJ) function, the mandibular condylar cartilage plays a prime role in the distribution and absorption of stresses generated over the condyle. Biomechanical characterization of the tissue under compression, however, is still incomplete. The present study investigates the regional variations in the elastic and equilibrium moduli of the condylar cartilage under high strains using unconfined compression and stress relaxation, with aims to facilitate future tissue engineering studies. Porcine condylar cartilages from five regions (anterior, central, lateral, medial, and posterior) were tested under unconfined compression. Elastic moduli were obtained from the linear regions of the stress-strain curves corresponding to the continuous deformation. Equilibrium moduli were obtained from the stress relaxation curves using the Kelvin model. The posterior region was the stiffest, followed by the middle (medial, central, and lateral) regions and the anterior region, respectively. Specifically, in terms of the equilibrium modulus, the posterior region was 1.4 times stiffer than the middle regions, which were in turn 1.7 times stiffer than the anterior region, although only the difference between anterior and posterior regions was statistically significant. No significant differences in stiffness were observed among the medial, central, lateral, and posterior regions. A positive correlation between the thickness and stiffness of the cartilage was observed, reflecting that their regional variations may be related phenomena caused in response to cartilage loading patterns. Condylar cartilage was less stiff under compression than in tension. In addition, condylar cartilage under compression appears to behave in a manner similar to the TMJ disc in terms of the magnitude of moduli and drastic initial drop in stress after a ramp strain.
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Affiliation(s)
- M. Singh
- Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, KS 66045
| | - M. S. Detamore
- Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, KS 66045
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38
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Gunja NJ, Uthamanthil RK, Athanasiou KA. Effects of TGF-beta1 and hydrostatic pressure on meniscus cell-seeded scaffolds. Biomaterials 2009; 30:565-73. [PMID: 18980779 PMCID: PMC2637152 DOI: 10.1016/j.biomaterials.2008.10.007] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Accepted: 10/02/2008] [Indexed: 11/28/2022]
Abstract
The combinatorial effects of TGF-beta1 and hydrostatic pressure (HP) were investigated on meniscus cell-seeded PLLA constructs using a two-phase sequential study. The objective was to identify potentially synergistic effects of these stimuli toward enhancing the biomechanical and compositional characteristics of the engineered constructs. In Phase I, the effects of TGF-beta1 were examined on the ability of meniscus cells to produce ECM. In Phase II, meniscus cell-seeded PLLA constructs were cultured for 4 wks with a combination of TGF-beta1 and HP (10 MPa, 0 Hz or 10 MPa, 0.1 Hz). TGF-beta1 was found to increase collagen and GAG deposition in the scaffolds 15-fold and 8-fold, respectively, in Phase I. In Phase II, the combination of TGF-beta1 and 10 MPa, 0 Hz HP resulted in 4-fold higher collagen deposition (additive increase), 3-fold higher GAG deposition and enhanced compressive properties (additive and synergistic increases), when compared to the unpressurized no growth factor culture control. Though significant correlations were observed between the compressive properties (moduli and viscosity), and the GAG and collagen content of the constructs, the correlations were stronger with collagen. This study provides robust evidence that growth factors and HP can be used successfully in combination to enhance the functional properties of in vitro engineered knee meniscus constructs.
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Affiliation(s)
- Najmuddin J Gunja
- Department of Bioengineering, Rice University, MS-142, P.O. Box 1892, Houston, TX 77251-1892, USA.
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39
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Athanasiou KA, Almarza AJ, Detamore MS, Kalpakci KN. Tissue Engineering of Temporomandibular Joint Cartilage. ACTA ACUST UNITED AC 2009. [DOI: 10.2200/s00198ed1v01y200906tis002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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40
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Snider G, Lomakin J, Singh M, Gehrke S, Detamore M. Regional Dynamic Tensile Properties of the TMJ Disc. J Dent Res 2008; 87:1053-7. [DOI: 10.1177/154405910808701112] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Although the TMJ disc has been well-characterized under tension and compression, dynamic viscoelastic regional and directional variations have heretofore not been investigated. We hypothesized that the intermediate zone under mediolateral tension would exhibit lower dynamic moduli compared with the other regions of the disc under either mediolateral or anteroposterior tension. Specimens were prepared from porcine discs (3 regions/direction), and dynamic tensile sweeps were performed at 1% strain over a frequency range of 0.1 to 100 rad/sec. Generally, the intermediate zone possessed the lowest storage and loss moduli, and the highest loss tangent. This study further accentuates the known distinct character of the intermediate zone by showing for the first time that these differences also extend to dynamic behavior, perhaps implicating the TMJ disc as a structure primarily exposed to predominantly anteroposterior tension via anterior and posterior attachments, with a need for great distension mediolaterally across the intermediate zone.
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Affiliation(s)
- G.R. Snider
- Department of Chemical and Petroleum Engineering, University of Kansas, 1530 W. 15th St., Room 4132, Lawrence, KS 66045-7609, USA
| | - J. Lomakin
- Department of Chemical and Petroleum Engineering, University of Kansas, 1530 W. 15th St., Room 4132, Lawrence, KS 66045-7609, USA
| | - M. Singh
- Department of Chemical and Petroleum Engineering, University of Kansas, 1530 W. 15th St., Room 4132, Lawrence, KS 66045-7609, USA
| | - S.H. Gehrke
- Department of Chemical and Petroleum Engineering, University of Kansas, 1530 W. 15th St., Room 4132, Lawrence, KS 66045-7609, USA
| | - M.S. Detamore
- Department of Chemical and Petroleum Engineering, University of Kansas, 1530 W. 15th St., Room 4132, Lawrence, KS 66045-7609, USA
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41
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Anderson DEJ, Athanasiou KA. Passaged goat costal chondrocytes provide a feasible cell source for temporomandibular joint tissue engineering. Ann Biomed Eng 2008; 36:1992-2001. [PMID: 18830818 DOI: 10.1007/s10439-008-9572-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Accepted: 09/19/2008] [Indexed: 11/25/2022]
Abstract
Costal cartilage is commonly harvested for various types of facial reconstructive surgery. The ability of costal chondrocytes (CCs) to produce relevant extracellular matrix, including glycosaminoglycans (GAGs) and collagens, makes them an appealing cell source for fibrocartilage engineering. In order to obtain enough cells for tissue engineering, however, cell expansion will likely be necessary. This study examined CCs at passages 0, 1, 3, and 5, as well as temporomandibular (TMJ) disc cells, in a scaffoldless tissue engineering approach. It was hypothesized that earlier passage constructs would have more cartilaginous proteins and less fibrocartilaginous proteins. TMJ disc constructs had over twice the collagen content of any other group, as well as the largest tensile properties; however, the substantial contraction of the constructs and limited cell numbers make it a non-feasible cell source for tissue engineering. In general, statistical differences in mechanical properties or collagen content of the various CC groups were not observed; however, significantly more GAG was produced in the passaged CCs than the primary CCs. More collagen type II was also observed in some of the passaged groups. These results suggest not only feasibility but potential superiority of passaged CCs over primary CCs, which may lead to functional engineered fibrocartilage.
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Affiliation(s)
- Deirdre E J Anderson
- Department of Bioengineering, MS-142, Rice University, PO Box 1892, Houston, TX 77251, USA
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42
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Chia HN, Hull ML. Compressive moduli of the human medial meniscus in the axial and radial directions at equilibrium and at a physiological strain rate. J Orthop Res 2008; 26:951-6. [PMID: 18271010 DOI: 10.1002/jor.20573] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The axial and radial compressive moduli of the human meniscus are important material properties in tibiofemoral joint models, but they have not been determined previously for fresh-frozen tissue. Our goals were to measure the moduli at equilibrium and at a physiological strain rate, to determine whether the axial and radial compressive moduli are equal for each type of loading, and to determine whether they depend on the region (i.e., anterior, middle, posterior) of the meniscus. Samples from each region from 10 fresh-frozen human medial menisci were tested in unconfined compression at four strain levels (3%, 6%, 9%, and 12%) at 32%/s, a strain rate determined to be physiologically relevant to walking, and then allowed to reach equilibrium in stress relaxation. At equilibrium, the axial and radial compressive moduli at 12% strain were 83.4 kPa and 76.1 kPa, respectively (p = 0.58), whereas at the physiological strain rate, the axial and radial compressive moduli at 12% strain were 718 kPa and 605 kPa, respectively (p = 0.61). At the physiological strain rate, the modulus increased with increasing strain (79.2 kPa at 3% strain vs. 662 kPa at 12% strain) and the modulus in the anterior region (1,048 kPa at 12% strain) was significantly greater than that in the posterior region (329 kPa at 12% strain) (p = 0.04). Our study supports a plane of isotropy for the material properties of meniscal tissue. However, the material behavior is strongly nonlinear because the compressive modulus is several orders of magnitude smaller than previously reported values for tensile modulus. Further, the compressive modulus depends on the activity of interest (i.e., static such as standing or dynamic such as walking) due to viscoelastic effects, the strain level, and the region of the tissue.
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Affiliation(s)
- Helena N Chia
- Biomedical Engineering Graduate Group, One Shields Avenue, University of California, Davis, California 95616, USA
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43
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Singh M, Detamore MS. Tensile properties of the mandibular condylar cartilage. J Biomech Eng 2008; 130:011009. [PMID: 18298185 DOI: 10.1115/1.2838062] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mandibular condylar cartilage plays a crucial role in temporomandibular joint (TMJ) function, which includes facilitating articulation with the temporomandibular joint disc and reducing loads on the underlying bone. The cartilage experiences considerable tensile forces due to direct compression and shear. However, only scarce information is available about its tensile properties. The present study aims to quantify the biomechanical characteristics of the mandibular condylar cartilage to aid future three-dimensional finite element modeling and tissue engineering studies. Porcine condylar cartilage was tested under uniaxial tension in two directions, anteroposterior and mediolateral, with three regions per direction. Stress relaxation behavior was modeled using the Kelvin model and a second-order generalized Kelvin model, and collagen fiber orientation was determined by polarized light microscopy. The stress relaxation behavior of the tissue was biexponential in nature. The tissue exhibited greater stiffness in the anteroposterior direction than in the mediolateral direction as reflected by higher Young's (2.4 times), instantaneous (1.9 times), and relaxed (1.9 times) moduli. No significant differences were observed among the regional properties in either direction. The predominantly anteroposterior macroscopic fiber orientation in the fibrous zone of condylar cartilage correlated well with the biomechanical findings. The condylar cartilage appears to be less stiff and less anisotropic under tension than the anatomically and functionally related TMJ disc. The anisotropy of the condylar cartilage, as evidenced by tensile behavior and collagen fiber orientation, suggests that the shear environment of the TMJ exposes the condylar cartilage to predominantly but not exclusively anteroposterior loading.
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Affiliation(s)
- M Singh
- Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, KS 66045, USA
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44
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Allen KD, Athanasiou KA. Scaffold and growth factor selection in temporomandibular joint disc engineering. J Dent Res 2008; 87:180-5. [PMID: 18218847 DOI: 10.1177/154405910808700205] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Temporomandibular joint disc tissue-engineering studies commonly fail to produce significant matrix before construct contraction. We hypothesized that poly-L-lactic acid (PLLA) non-woven meshes would limit contraction, allow for comprehensive mechanical evaluation, and maintain viability relative to polyglycolic acid (PGA) non-woven mesh controls. Additionally, we proposed that growth factor stimulation, while limiting contraction, would increase construct properties relative to previous reports. After 4 wks, cell proliferation and matrix deposition were similar between the two meshes, but PGA constructs had contracted significantly. Furthermore, only PLLA constructs could be tested in tension and compression. Additional PLLA constructs were formed, then treated with insulin-like growth factor-1 (10 ng/mL), transforming growth factor-beta 1 (5 ng/mL), or transforming growth factor-beta 3 (5 ng/mL). Transforming growth factor-beta 1 yielded the most cells, collagen, and glycosaminoglycans at 6 wks; these constructs also demonstrated improved mechanics. Analysis of these data demonstrated significant temporomandibular joint disc-engineering potential for PLLA and transforming growth factor-beta 1.
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Affiliation(s)
- K D Allen
- Department of Bioengineering, Rice University, MS-142, PO Box 1892, Houston, TX 77251-1892, USA
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45
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Johns DE, Athanasiou KA. Design characteristics for temporomandibular joint disc tissue engineering: learning from tendon and articular cartilage. Proc Inst Mech Eng H 2007; 221:509-26. [PMID: 17822153 DOI: 10.1243/09544119jeim158] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Tissue engineering of chondrocytic or fibroblastic musculoskeletal tissues has been relatively well studied compared with that of the temporomandibular joint (TMJ) disc. Early attempts at tissue engineering the disc have been misguided owing to a lack of understanding of the composition and function of the TMJ disc. The objective of this review is to compare the TMJ disc with a chondrocytic tissue (hyaline articular cartilage) and a fibroblastic tissue (tendon) to understand better the properties of this fibrocartilaginous tissue. The TMJ disc has 25 times more glycosaminoglycan (GAG) per dry weight than tendon but half that of articular cartilage. The disc's tensile modulus is six times more than cartilage but orders less than tendon. The GAG content and tensile modulus suggest that the TMJ disc is characterized as a tissue between hyaline cartilage and tendon, but the disc appears more tendon like when considering its collagen make-up and cell content. Like tendon, the TMJ disc contains primarily collagen type I at 85 per cent per dry weight, while articular cartilage has 30 per cent less collagen, which is type II. Knowledge of quantitative comparisons between joint tissues can give extensive insight into how to improve tissue engineering of the TMJ disc.
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Affiliation(s)
- D E Johns
- Department of Bioengineering, Rice University, Houston, Texas 77251, USA
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46
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Allen KD, Athanasiou KA. Effect of passage and topography on gene expression of temporomandibular joint disc cells. ACTA ACUST UNITED AC 2007; 13:101-10. [PMID: 17518584 DOI: 10.1089/ten.2006.0094] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The temporomandibular joint (TMJ) disc is maintained by a population of fibrochondrocytes. Although articular chondrocytes exhibit zonal differences and de-differentiate in monolayer culture, such variations are unknown for fibrochondrocytic populations. This study's objective was to define topographical cellular variations in the porcine TMJ disc and investigate changes in the disc's gene expression levels over multiple passages using quantitative reverse transcriptase polymerase chain reaction. For topographical characterization, samples were acquired from posterior, anterior, lateral, medial, and intermediate zone sections and subdivided into inferior and superior halves. For passage characterization, cells were plated and passaged for 35 days, with samples acquired at every passage. The medial region had the lowest expression of genes indicative of fibroblastic activity, but in general, topographical variations were limited. Passage effects were evident; gene expression levels of aggrecan, collagen type I, and collagen type II dropped 20%, 23%, and 73% per passage, respectively. In contrast, decorin and glyseraldehyde-3-phosphate dehydrogenase gene expression increased 33% and 27% per passage, respectively. These data indicate that TMJ disc cells undergo significant changes due to monolayer expansion, experiencing losses in major chondrocytic markers (aggrecan and collagen type II) and fibroblastic markers (collagen type I) and posing a serious impediment to studies in which cell passaging is required.
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Affiliation(s)
- Kyle D Allen
- Department of Bioengineering, Rice University, Houston, Texas 77251-1892, USA
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Johns DE, Athanasiou KA. Improving culture conditions for temporomandibular joint disc tissue engineering. Cells Tissues Organs 2007; 185:246-57. [PMID: 17587799 DOI: 10.1159/000102173] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2007] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The temporomandibular joint (TMJ) is extremely important for activities like eating and talking, which can become painful and difficult for patients with TMJ dysfunction. Tissue engineering is a potential alternative to current surgical interventions through replacement of diseased or injured tissue with a functional construct. Since research with TMJ disc cells began relatively recently, optimal culturing conditions must be determined. METHODS Metabolic additives, L-glutamine, L-alanyl-L-glutamine, sodium pyruvate, and insulin, were examined for their effects on TMJ disc cells in monolayer. Effects of L-proline were examined in three-dimensional (3-D) culture at concentrations of 0, 25 and 100 mg/l. RESULTS The combination of L-glutamine, sodium pyruvate, and insulin improved cell proliferation rates without affecting collagen production or gene expression. No differences were observed in mechanical properties of the engineered constructs; however, collagen and glycosaminoglycan quantities normalized to cell number decreased at the highest concentration of L-proline. CONCLUSION This work identified supplements for 2-D monolayer expansion. Other supplements or culture conditions still need to be investigated for 3-D tissue production. This work improves upon porcine TMJ disc cell culturing conditions, taking us closer to being able to engineer the TMJ disc.
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Affiliation(s)
- D E Johns
- Department of Bioengineering, Rice University, Houston, Texas 77251, USA
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Abstract
The potential impact of a tissue-engineered temporomandibular joint (TMJ) disc is immense. Currently, patients suffering from a severely dysfunctional TMJ have few options. Facing the general lack of safe, effective TMJ disc implants, many patients undergo discectomy, a procedure that removes the injured TMJ disc in hopes of reducing debilitating symptoms associated with severe TMJ disorders. This procedure may not be ideal as the TMJ is left without an important functional component. Tissue engineering is a promising approach for the creation of viable, effective implants. The first attempt to investigate TMJ disc cells on a biomaterial was conducted in 1991. The first TMJ tissue-engineered constructs to be tested biochemically and biomechanically were formed in 1994; however, in examining this study in retrospect, it is clear how little TMJ knowledge was available at that time. Within the last 10 to 15 years, multiple studies have investigated critical TMJ disc characteristics, and while this characterization is not complete, these data have created a solid foundation for tissue-engineering research. Thus, the last 5 years have yielded core studies investigating the principal elements of tissue engineering: scaffold, cell source, and biological/biomechanical stimuli. Although TMJ disc tissue engineering is still in its formative years, its future is quite promising. Key studies are now being conducted that will assist in the establishment of a solid TMJ disc tissue-engineering approach. As the challenges of tissue engineering are faced and met, the ultimate goal of creating a functional biological implant nears.
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Affiliation(s)
- Kyle D Allen
- Department of Bioengineering, Rice University, Houston, Texas 77251-1892, USA
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