1
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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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2
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McKinley JP, O'Connell GD. Review of state-of-the-art micro and macro-bioreactors for the intervertebral disc. J Biomech 2024; 165:111964. [PMID: 38412621 DOI: 10.1016/j.jbiomech.2024.111964] [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: 08/08/2023] [Revised: 01/02/2024] [Accepted: 01/23/2024] [Indexed: 02/29/2024]
Abstract
Lower back pain continues to be a global epidemic, limiting quality of life and ability to work, due in large part to symptomatic disc degeneration. Development of more effective and less invasive biological strategies are needed to treat disc degeneration. In vitro models such as macro- or micro-bioreactors or mechanically active organ-chips hold great promise in reducing the need for animal studies that may have limited clinical translatability, due to harsher and more complex mechanical loading environments in human discs than in most animal models. This review highlights the complex loading conditions of the disc in situ, evaluates state-of-the-art designs for applying such complex loads across multiple length scales, from macro-bioreactors that load whole discs to organ-chips that aim to replicate cellular or engineered tissue loading. Emphasis was placed on the rapidly evolving more customizable organ-chips, given their greater potential for studying the progression and treatment of symptomatic disc degeneration. Lastly, this review identifies new trends and challenges for using organ-chips to assess therapeutic strategies.
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Affiliation(s)
- Jonathan P McKinley
- Berkeley BioMechanics Laboratory, Department of Mechanical Engineering, University of California, Berkeley 94720, CA, USA.
| | - Grace D O'Connell
- Berkeley BioMechanics Laboratory, Department of Mechanical Engineering, University of California, Berkeley 94720, CA, USA.
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3
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Yin X, Vesvoranan O, Andreopoulos F, Dauer EA, Gu W, Huang CYC. Analysis of Extracellular ATP Distribution in the Intervertebral Disc. Ann Biomed Eng 2024; 52:542-555. [PMID: 37934317 DOI: 10.1007/s10439-023-03398-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Accepted: 10/25/2023] [Indexed: 11/08/2023]
Abstract
Progressive loss of proteoglycans (PGs) is the major biochemical change during intervertebral disc (IVD) degeneration. Adenosine triphosphate (ATP) as the primary energy source is not only critical for cell survival but also serves as a building block in PG synthesis. Extracellular ATP can mediate a variety of physiological functions and was shown to promote extracellular matrix (ECM) production in the IVD. Therefore, the objective of this study was to develop a 3D finite element model to predict extracellular ATP distribution in the IVD and evaluate the impact of degeneration on extracellular ATP distribution. A novel 3D finite element model of the IVD was developed by incorporating experimental measurements of ATP metabolism and ATP-PG binding kinetics into the mechano-electrochemical mixture theory. The new model was validated by experimental data of porcine IVD, and then used to analyze the extracellular distribution of ATP in human IVDs. Extracellular ATP was shown to bind specifically with PGs in IVD ECM. It was found that annulus fibrosus cells hydrolyze ATP faster than that of nucleus pulposus (NP) cells whereas NP cells exhibited a higher ATP release. The distribution of extracellular ATP in a porcine model was consistent with experimental data in our previous study. The predictions from a human IVD model showed a high accumulation of extracellular ATP in the NP region, whereas the extracellular ATP level was reduced with tissue degeneration. This study provides an understanding of extracellular ATP metabolism and its potential biological influences on the IVD via purinergic signaling.
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Affiliation(s)
- Xue Yin
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA
| | - Oraya Vesvoranan
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA
| | - Fotios Andreopoulos
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA
| | - Edward A Dauer
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA
| | - Weiyong Gu
- Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL, USA
| | - C-Y Charles Huang
- Department of Biomedical Engineering, College of Engineering, University of Miami, P.O. Box 248294, Coral Gables, FL, 33124-0621, USA.
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4
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Huang CY, Loo DM, Gu W. Modeling of glycosaminoglycan biosynthesis in intervertebral disc cells. Comput Biol Med 2023; 162:107039. [PMID: 37295387 DOI: 10.1016/j.compbiomed.2023.107039] [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: 10/05/2022] [Revised: 05/05/2023] [Accepted: 05/12/2023] [Indexed: 06/12/2023]
Abstract
Loss of proteoglycan (PG) is a potential factor responsible for degeneration of the intervertebral disc (IVD). PG consists of a core protein with covalently attached glycosaminoglycan (GAG) chains. The objective of this study was to develop a mathematical model of GAG biosynthesis to investigate the effects of glycolytic enzymes on GAG biosynthesis of IVD cells. A new mathematical model of GAG biosynthesis was developed for IVD cells by incorporating biosynthesis of uridine diphosphate-sugars into the glycolytic pathway. This new model showed good agreement between the model predictions of intracellular ATP content and GAG biosynthesis and experimental data measured at different external glucose levels. The quantitative analyses demonstrated that GAG biosynthesis may be sensitive to the activities of hexokinase (HK) and phosphofructokinase (PFK), especially at low glucose supply, with GAG biosynthesis being significantly enhanced by a slight increase in activities of HK and PFK. This suggests that metabolic reprogramming could be a potential strategy for promoting PG biosynthesis in IVD cells. Furthermore, it was shown that GAG biosynthesis may be promoted by increasing intracellular glutamine concentration or activity of glutamine:fructose-6-phosphate amidotransferase in the hexamine pathway. This study provides a better understanding of the relationship between glycolysis and PG biosynthesis in IVD cells. The theoretical framework developed in this study is useful for studying the role of glycolysis in disc degeneration and developing new preventive and treatment strategies for degeneration of the IVD.
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Affiliation(s)
- Chun-Yuh Huang
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA.
| | - Daniela M Loo
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA
| | - Weiyong Gu
- Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL, USA
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5
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Samanta A, Lufkin T, Kraus P. Intervertebral disc degeneration-Current therapeutic options and challenges. Front Public Health 2023; 11:1156749. [PMID: 37483952 PMCID: PMC10359191 DOI: 10.3389/fpubh.2023.1156749] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 06/12/2023] [Indexed: 07/25/2023] Open
Abstract
Degeneration of the intervertebral disc (IVD) is a normal part of aging. Due to the spine's declining function and the development of pain, it may affect one's physical health, mental health, and socioeconomic status. Most of the intervertebral disc degeneration (IVDD) therapies today focus on the symptoms of low back pain rather than the underlying etiology or mechanical function of the disc. The deteriorated disc is typically not restored by conservative or surgical therapies that largely focus on correcting symptoms and structural abnormalities. To enhance the clinical outcome and the quality of life of a patient, several therapeutic modalities have been created. In this review, we discuss genetic and environmental causes of IVDD and describe promising modern endogenous and exogenous therapeutic approaches including their applicability and relevance to the degeneration process.
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Allais R, Capart A, Da Silva A, Boiron O. Biomechanical consequences of the intervertebral disc centre of rotation kinematics during lateral bending and axial rotation. Sci Rep 2023; 13:3172. [PMID: 36823433 PMCID: PMC9950088 DOI: 10.1038/s41598-023-29551-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 02/06/2023] [Indexed: 02/25/2023] Open
Abstract
The location of the instantaneous centre of rotation (ICR) of a lumbar unit has a considerable clinical importance as a spinal health estimator. Consequently, many studies have been conducted to measure or estimate the ICR during rotations in the three anatomical planes; however the results reported are widely scattered. Even if some inter-subjects variability is to be expected, such inconsistencies are likely explained by the differences in methods and experiments. Therefore, in this paper we seek to model three behaviours of the ICR during lateral bending and axial rotation based on results published in the literature. In order to assess the metabolic and mechanical sensibility to the assumption made on the ICR kinematics, we used a previously validated three dimensional non-linear poroelastic model of a porcine intervertebral disc to simulate physiological lateral and axial rotations. The impact of the geometry was also briefly investigated by considering a 11[Formula: see text] wedge angle. From our simulations, it appears that the hypothesis made on the ICR location does not significantly affect the critical nutrients concentrations but gives disparate predictions of the intradiscal pressure at the centre of the disc (variation up to 0.7 MPa) and of the displacement fields (variation up to 0.4 mm). On the contrary, the wedge angle does not influence the estimated intradiscal pressure but leads to minimal oxygen concentration decreased up to 33% and increased maximal lactate concentration up to 13%. While we can not settle on which definition of the ICR is more accurate, this work suggests that patient-specific modeling of the ICR is required and brings new insights that can be useful for the development of new tools or the design of surgical material such as total lumbar disc prostheses.
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Affiliation(s)
- Roman Allais
- CNRS, Centrale Marseille, IRPHE, Aix Marseille Univ, 13013, Marseille, France.
| | - Antoine Capart
- grid.462364.10000 0000 9151 9019Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, 13013 Marseille, France
| | - Anabela Da Silva
- grid.462364.10000 0000 9151 9019Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, 13013 Marseille, France
| | - Olivier Boiron
- grid.5399.60000 0001 2176 4817CNRS, Centrale Marseille, IRPHE, Aix Marseille Univ, 13013 Marseille, France
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7
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Predictive Factors for Poor Outcome following Chemonucleolysis with Condoliase in Lumbar Disc Herniation. MEDICINA (KAUNAS, LITHUANIA) 2022; 58:medicina58121868. [PMID: 36557070 PMCID: PMC9781337 DOI: 10.3390/medicina58121868] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 12/11/2022] [Accepted: 12/14/2022] [Indexed: 12/24/2022]
Abstract
Background and Objectives: Condoliase, a chondroitin sulfate ABC endolyase, is a novel and minimally invasive chemonucleolytic drug for lumbar disc herniation. Despite the growing number of treatments for lumbar disc herniation, the predicting factors for poor outcomes following treatment remain unclear. The aim of this study was to determine the predictive factors for unsuccessful clinical outcome following condoliase therapy. Material and Methods: We performed a retrospective single-center analysis of 101 patients who underwent chemonucleolysis with condoliase from January 2019 to December 2021. Patients were divided into good outcome (i.e., favorable outcome) and poor outcome (i.e., requiring additional surgical treatment) groups. Patient demographics and imaging findings were collected. Clinical outcomes were evaluated using the numerical rating scale and Japanese Orthopaedic Association scores at baseline and at 1- and 3-month follow-up. Pretreatment indicators for additional surgery were compared between the 2 groups. Results: There was a significant difference in baseline leg numbness between the good outcome and poor outcome groups (6.27 ± 1.90 vs. 4.42 ± 2.90, respectively; p = 0.033). Of the 101 included patients, 32 received a preoperative computed tomography scan. In those patients, the presence of calcification or ossification in disc hernia occurred more often in the poor outcome group (61.5% vs. 5.3%, respectively; p < 0.001; odds ratio = 22.242; p = 0.014). Receiver-operating characteristics curve analysis for accompanying calcification or ossification showed an area under the curve of 0.858 (95% confidence interval, 0.715−1.000; p = 0.001). Conclusions: Calcified or ossified disc herniation may be useful predictors of unsuccessful treatment in patients with condoliase administration.
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8
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Tang SN, Bonilla AF, Chahine NO, Colbath AC, Easley JT, Grad S, Haglund L, Le Maitre CL, Leung V, McCoy AM, Purmessur D, Tang SY, Zeiter S, Smith LJ. Controversies in spine research: Organ culture versus in vivo models for studies of the intervertebral disc. JOR Spine 2022; 5:e1235. [PMID: 36601369 PMCID: PMC9799089 DOI: 10.1002/jsp2.1235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 11/14/2022] [Accepted: 11/17/2022] [Indexed: 11/30/2022] Open
Abstract
Intervertebral disc degeneration is a common cause of low back pain, the leading cause of disability worldwide. Appropriate preclinical models for intervertebral disc research are essential to achieving a better understanding of underlying pathophysiology and for the development, evaluation, and translation of more effective treatments. To this end, in vivo animal and ex vivo organ culture models are both widely used by spine researchers; however, the relative strengths and weaknesses of these two approaches are a source of ongoing controversy. In this article, members from the Spine and Preclinical Models Sections of the Orthopedic Research Society, including experts in both basic and translational spine research, present contrasting arguments in support of in vivo animal models versus ex vivo organ culture models for studies of the disc, supported by a comprehensive review of the relevant literature. The objective is to provide a deeper understanding of the respective advantages and limitations of these approaches, and advance the field toward a consensus with respect to appropriate model selection and implementation. We conclude that complementary use of several model types and leveraging the unique advantages of each is likely to result in the highest impact research in most instances.
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Affiliation(s)
- Shirley N. Tang
- Department of Biomedical EngineeringThe Ohio State UniversityColumbusOhioUSA
| | - Andres F. Bonilla
- Preclinical Surgical Research Laboratory, Department of Clinical SciencesColorado State UniversityFort CollinsColoradoUSA
| | - Nadeen O. Chahine
- Departments of Orthopedic Surgery and Biomedical EngineeringColumbia UniversityNew YorkNew YorkUSA
| | - Aimee C. Colbath
- Department of Clinical Sciences, College of Veterinary MedicineCornell UniversityIthacaNew YorkUSA
| | - Jeremiah T. Easley
- Preclinical Surgical Research Laboratory, Department of Clinical SciencesColorado State UniversityFort CollinsColoradoUSA
| | | | | | | | - Victor Leung
- Department of Orthopaedics and TraumatologyThe University of Hong KongHong KongSARChina
| | - Annette M. McCoy
- Department of Veterinary Clinical MedicineUniversity of IllinoisUrbanaIllinoisUSA
| | - Devina Purmessur
- Department of Biomedical EngineeringThe Ohio State UniversityColumbusOhioUSA
| | - Simon Y. Tang
- Department of Orthopaedic SurgeryWashington University in St LouisSt LouisMissouriUSA
| | | | - Lachlan J. Smith
- Departments of Orthopaedic Surgery and NeurosurgeryUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA,Translational Musculoskeletal Research CenterCorporal Michael J. Crescenz VA Medical CenterPhiladelphiaPennsylvaniaUSA
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9
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Eremina G, Smolin A, Xie J, Syrkashev V. Development of a Computational Model of the Mechanical Behavior of the L4-L5 Lumbar Spine: Application to Disc Degeneration. MATERIALS (BASEL, SWITZERLAND) 2022; 15:6684. [PMID: 36234026 PMCID: PMC9572952 DOI: 10.3390/ma15196684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/22/2022] [Accepted: 09/23/2022] [Indexed: 06/16/2023]
Abstract
Degenerative changes in the lumbar spine significantly reduce the quality of life of people. In order to fully understand the biomechanics of the affected spine, it is crucial to consider the biomechanical alterations caused by degeneration of the intervertebral disc (IVD). Therefore, this study is aimed at the development of a discrete element model of the mechanical behavior of the L4-L5 spinal motion segment, which covers all the degeneration grades from healthy IVD to its severe degeneration, and numerical study of the influence of the IVD degeneration on stress state and biomechanics of the spine. In order to analyze the effects of IVD degeneration on spine biomechanics, we simulated physiological loading conditions using compressive forces. The results of modeling showed that at the initial stages of degenerative changes, an increase in the amplitude and area of maximum compressive stresses in the disc is observed. At the late stages of disc degradation, a decrease in the value of intradiscal pressure and a shift in the maximum compressive stresses in the dorsal direction is observed. Such an influence of the degradation of the geometric and mechanical parameters of the tissues of the disc leads to the effect of bulging, which in turn leads to the formation of an intervertebral hernia.
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Affiliation(s)
- Galina Eremina
- Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, Pr. Akademicheskii, 2/4, 634055 Tomsk, Russia
| | - Alexey Smolin
- Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, Pr. Akademicheskii, 2/4, 634055 Tomsk, Russia
| | - Jing Xie
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China
| | - Vladimir Syrkashev
- Department of General Medicine, Siberian State Medical University, Moskovsky Trakt, 2, 634050 Tomsk, Russia
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10
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Importance of Matrix Cues on Intervertebral Disc Development, Degeneration, and Regeneration. Int J Mol Sci 2022; 23:ijms23136915. [PMID: 35805921 PMCID: PMC9266338 DOI: 10.3390/ijms23136915] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 06/17/2022] [Accepted: 06/20/2022] [Indexed: 01/25/2023] Open
Abstract
Back pain is one of the leading causes of disability worldwide and is frequently caused by degeneration of the intervertebral discs. The discs’ development, homeostasis, and degeneration are driven by a complex series of biochemical and physical extracellular matrix cues produced by and transmitted to native cells. Thus, understanding the roles of different cues is essential for designing effective cellular and regenerative therapies. Omics technologies have helped identify many new matrix cues; however, comparatively few matrix molecules have thus far been incorporated into tissue engineered models. These include collagen type I and type II, laminins, glycosaminoglycans, and their biomimetic analogues. Modern biofabrication techniques, such as 3D bioprinting, are also enabling the spatial patterning of matrix molecules and growth factors to direct regional effects. These techniques should now be applied to biochemically, physically, and structurally relevant disc models incorporating disc and stem cells to investigate the drivers of healthy cell phenotype and differentiation. Such research will inform the development of efficacious regenerative therapies and improved clinical outcomes.
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11
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Impact of Microenvironmental Changes during Degeneration on Intervertebral Disc Progenitor Cells: A Comparison with Mesenchymal Stem Cells. Bioengineering (Basel) 2022; 9:bioengineering9040148. [PMID: 35447707 PMCID: PMC9025850 DOI: 10.3390/bioengineering9040148] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/16/2022] [Accepted: 03/17/2022] [Indexed: 12/22/2022] Open
Abstract
Intervertebral disc (IVD) degeneration occurs with natural ageing and is linked to low back pain, a common disease. As an avascular tissue, the microenvironment inside the IVD is harsh. During degeneration, the condition becomes even more compromised, presenting a significant challenge to the survival and function of the resident cells, as well as to any regeneration attempts using cell implantation. Mesenchymal stem cells (MSCs) have been proposed as a candidate stem cell tool for IVD regeneration. Recently, endogenous IVD progenitor cells have been identified inside the IVD, highlighting their potential for self-repair. IVD progenitor cells have properties similar to MSCs, with minor differences in potency and surface marker expression. Currently, it is unclear how IVD progenitor cells react to microenvironmental factors and in what ways they possibly behave differently to MSCs. Here, we first summarized the microenvironmental factors presented in the IVD and their changes during degeneration. Then, we analyzed the available studies on the responses of IVD progenitor cells and MSCs to these factors, and made comparisons between these two types of cells, when possible, in an attempt to achieve a clear understanding of the characteristics of IVD progenitor cells when compared to MSCs; as well as, to provide possible clues to cell fate after implantation, which may facilitate future manipulation and design of IVD regeneration studies.
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12
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McDonnell EE, Buckley CT. Consolidating and re-evaluating the human disc nutrient microenvironment. JOR Spine 2022; 5:e1192. [PMID: 35386756 PMCID: PMC8966889 DOI: 10.1002/jsp2.1192] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 12/14/2021] [Accepted: 01/07/2022] [Indexed: 12/19/2022] Open
Abstract
Background Despite exciting advances in regenerative medicine, cell‐based strategies for treating degenerative disc disease remain in their infancy. To maximize the potential for successful clinical translation, a more thorough understanding of the in vivo microenvironment is needed to better determine and predict how cell therapies will respond when administered in vivo. Aims This work aims to reflect on the in vivo nutrient microenvironment of the degenerating IVD through consolidating what has already been measured together with investigative in silico models. Materials and Methods This work uses in silico modeling, underpinned by more recent experimentally determined parameters of degeneration and nutrient transport from the literature, to re‐evaluate the current knowledge in terms of grade‐specific stages of degeneration. Results Through modeling only the metabolically active cell population, this work predicts slightly higher glucose concentrations compared to previous in silico models, while the predicted results show good agreement with previous intradiscal pH and oxygen measurements. Increasing calcification with degeneration limits nutrient transport into the IVD and initiates a build‐up of acidity; however, its effect is compensated somewhat by a reduction in diffusional distance due to decreasing disc height. Discussion This work advances in silico modeling through a strong foundation of experimentally determined grade‐specific input parameters. Taken together, pre‐existing measurements and predicted results suggest that metabolite concentrations may not be as critically low as commonly believed, with calcification not appearing to have a detrimental effect at stages of degeneration when cell therapies are an appropriate intervention. Conclusion Overall, our initiative is to provoke greater deliberation and consideration of the nutrient microenvironment when performing in vitro cell culture and cell therapy development. This work highlights urgency for robust experimental glucose measurements in healthy and degenerating IVDs, not only to validate in silico models but to significantly advance the field in fully elucidating the nutrient microenvironment and refining in vitro techniques to accelerate clinical translation.
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Affiliation(s)
- Emily E McDonnell
- Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College Dublin The University of Dublin Dublin Ireland.,Discipline of Mechanical, Manufacturing and Biomedical Engineering, School of Engineering, Trinity College Dublin The University of Dublin Dublin Ireland
| | - Conor T Buckley
- Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College Dublin The University of Dublin Dublin Ireland.,Discipline of Mechanical, Manufacturing and Biomedical Engineering, School of Engineering, Trinity College Dublin The University of Dublin Dublin Ireland.,Advanced Materials and Bioengineering Research (AMBER) Centre, Royal College of Surgeons in Ireland & Trinity College Dublin The University of Dublin Dublin Ireland.,Tissue Engineering Research Group, Department of Anatomy and Regenerative Medicine Royal College of Surgeons in Ireland Dublin Ireland
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13
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Volz M, Elmasry S, Jackson AR, Travascio F. Computational Modeling Intervertebral Disc Pathophysiology: A Review. Front Physiol 2022; 12:750668. [PMID: 35095548 PMCID: PMC8793742 DOI: 10.3389/fphys.2021.750668] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 12/15/2021] [Indexed: 12/31/2022] Open
Abstract
Lower back pain is a medical condition of epidemic proportion, and the degeneration of the intervertebral disc has been identified as a major contributor. The etiology of intervertebral disc (IVD) degeneration is multifactorial, depending on age, cell-mediated molecular degradation processes and genetics, which is accelerated by traumatic or gradual mechanical factors. The complexity of such intertwined biochemical and mechanical processes leading to degeneration makes it difficult to quantitatively identify cause–effect relationships through experiments. Computational modeling of the IVD is a powerful investigative tool since it offers the opportunity to vary, observe and isolate the effects of a wide range of phenomena involved in the degenerative process of discs. This review aims at discussing the main findings of finite element models of IVD pathophysiology with a special focus on the different factors contributing to physical changes typical of degenerative phenomena. Models presented are subdivided into those addressing role of nutritional supply, progressive biochemical alterations stemming from an imbalance between anabolic and catabolic processes, aging and those considering mechanical factors as the primary source that induces morphological change within the disc. Limitations of the current models, as well as opportunities for future computational modeling work are also discussed.
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Affiliation(s)
- Mallory Volz
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, United States
| | - Shady Elmasry
- Department of Biomechanics, Hospital for Special Surgery, New York, NY, United States
| | - Alicia R. Jackson
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, United States
| | - Francesco Travascio
- Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL, United States
- Department of Orthopaedic Surgery, University of Miami, Miami, FL, United States
- Max Biedermann Institute for Biomechanics, Mount Sinai Medical Center, Miami Beach, FL, United States
- *Correspondence: Francesco Travascio,
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14
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Xu H, Dong R, Zeng Q, Fang L, Ge Q, Xia C, Zhang P, Lv S, Zou Z, Wang P, Li J, Ruan H, Hu S, Wu C, Jin H, Tong P. Col9a2 gene deletion accelerates the degeneration of intervertebral discs. Exp Ther Med 2022; 23:207. [PMID: 35126710 PMCID: PMC8796617 DOI: 10.3892/etm.2022.11130] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 12/22/2021] [Indexed: 11/06/2022] Open
Affiliation(s)
- Huihui Xu
- The First College of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, P.R. China
| | - Rui Dong
- The First College of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, P.R. China
| | - Qinghe Zeng
- The First College of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, P.R. China
| | - Liang Fang
- The First College of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, P.R. China
| | - Qinwen Ge
- The First College of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, P.R. China
| | - Chenjie Xia
- The First College of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, P.R. China
| | - Peng Zhang
- The First College of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, P.R. China
| | - Shuaijie Lv
- The First College of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, P.R. China
| | - Zhen Zou
- The First College of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, P.R. China
| | - Pinger Wang
- The First College of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, P.R. China
| | - Ju Li
- The First College of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, P.R. China
| | - Hongfeng Ruan
- The First College of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, P.R. China
| | - Songfeng Hu
- Department of Orthopaedics and Traumatology, Shaoxing Hospital of Traditional Chinese Medicine, Shaoxing, Zhejiang 312000, P.R. China
| | - Chengliang Wu
- The First College of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, P.R. China
| | - Hongting Jin
- The First College of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, P.R. China
| | - Peijian Tong
- The First College of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, P.R. China
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15
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Wang Z, Shen J, Feng E, Jiao Y. AMPK as a Potential Therapeutic Target for Intervertebral Disc Degeneration. Front Mol Biosci 2021; 8:789087. [PMID: 34957218 PMCID: PMC8692877 DOI: 10.3389/fmolb.2021.789087] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 11/24/2021] [Indexed: 12/25/2022] Open
Abstract
As the principal reason for low back pain, intervertebral disc degeneration (IDD) affects the health of people around the world regardless of race or region. Degenerative discs display a series of characteristic pathological changes, including cell apoptosis, senescence, remodeling of extracellular matrix, oxidative stress and inflammatory local microenvironment. As a serine/threonine-protein kinase in eukaryocytes, AMP-activated protein kinase (AMPK) is involved in various cellular processes through the modulation of cell metabolism and energy balance. Recent studies have shown the abnormal activity of AMPK in degenerative disc cells. Besides, AMPK regulates multiple crucial biological behaviors in IDD. In this review, we summarize the pathophysiologic changes of IDD and activation process of AMPK. We also attempt to generalize the role of AMPK in the pathogenesis of IDD. Moreover, therapies targeting AMPK in alleviating IDD are analyzed, for better insight into the potential of AMPK as a therapeutic target.
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Affiliation(s)
- Zhen Wang
- Department of Orthopedics, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Jianxiong Shen
- Department of Orthopedics, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Erwei Feng
- Department of Orthopedics, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Yang Jiao
- Department of Orthopedics, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
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16
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Shalash W, Ahrens SR, Bardonova LA, Byvaltsev VA, Giers MB. Patient-specific apparent diffusion maps used to model nutrient availability in degenerated intervertebral discs. JOR Spine 2021; 4:e1179. [PMID: 35005445 PMCID: PMC8717112 DOI: 10.1002/jsp2.1179] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 09/29/2021] [Accepted: 10/25/2021] [Indexed: 01/07/2023] Open
Abstract
INTRODUCTION In this study, magnetic resonance imaging data was used to (1) model IVD-specific gradients of glucose, oxygen, lactate, and pH; and (2) investigate possible effects of covariate factors (i.e., disc geometry, and mean apparent diffusion coefficient values) on the IVD's microenvironment. Mathematical modeling of the patient's specific IVD microenvironment could be important when selecting patients for stem cell therapy due to the increased nutrient demand created by that treatment. MATERIALS AND METHODS Disc geometry and water diffusion coefficients were extracted from MRIs of 37 patients using sagittal T1-weighted images, T2-weighted images, and ADC Maps. A 2-D steady state finite element mathematical model was developed in COMSOL Multiphysics® 5.4 to compute concentration maps of glucose, oxygen, lactate and pH. RESULTS Concentration of nutrients (i.e., glucose, and oxygen) dropped with increasing distance from the cartilaginous endplates (CEP), whereas acidity levels increased. Most discs experienced poor nutrient levels along with high acidity values in the inner annulus fibrosus (AF). The disc's physiological microenvironment became more deficient as degeneration progressed. For example, minimum glucose concentration in grade 4 dropped by 31.1% compared to grade 3 (p < 0.0001). The model further suggested a strong effect of the following parameters: disc size, AF and CEP diffusivities, metabolic reactions, and cell density on solute concentrations in the disc (p < 0.05). CONCLUSION The significance of this work implies that the individual morphology and physiological conditions of each disc, even among discs of the same Pfirrmann grade, should be evaluated when modeling IVD solute concentrations.
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Affiliation(s)
- Ward Shalash
- School of Chemical, Biological and Environmental EngineeringOregon State UniversityCorvallisOregonUSA
| | - Sonia R. Ahrens
- School of Chemical, Biological and Environmental EngineeringOregon State UniversityCorvallisOregonUSA
| | - Liudmila A. Bardonova
- School of Chemical, Biological and Environmental EngineeringOregon State UniversityCorvallisOregonUSA
- Irkutsk State Medical UniversityIrkutskRussia
| | - Vadim A. Byvaltsev
- Irkutsk State Medical UniversityIrkutskRussia
- Railway Clinical Hospital at the Irkutsk‐Passazhirsky StationIrkutskRussia
| | - Morgan B. Giers
- School of Chemical, Biological and Environmental EngineeringOregon State UniversityCorvallisOregonUSA
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17
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McDonnell EE, Buckley CT. Investigating the physiological relevance of ex vivo disc organ culture nutrient microenvironments using in silico modeling and experimental validation. JOR Spine 2021; 4:e1141. [PMID: 34337330 PMCID: PMC8313156 DOI: 10.1002/jsp2.1141] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/22/2021] [Accepted: 01/28/2021] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Ex vivo disc organ culture systems have become a valuable tool for the development and pre-clinical testing of potential intervertebral disc (IVD) regeneration strategies. Bovine caudal discs have been widely selected due to their large availability and comparability to human IVDs in terms of size and biochemical composition. However, despite their extensive use, it remains to be elucidated whether their nutrient microenvironment is comparable to human degeneration. AIMS This work aims to create the first experimentally validated in silico model which can be used to predict and characterize the metabolite concentrations within ex vivo culture systems. MATERIALS & METHODS Finite element models of cultured discs governed by previously established coupled reaction-diffusion equations were created using COMSOL Multiphysics. Experimental validation was performed by measuring oxygen, glucose and pH levels within discs cultured for 7 days, in a static compression bioreactor. RESULTS The in silico model was successfully validated through good agreement between the predicted and experimentally measured concentrations. For an ex vivo organ cultured in high glucose medium (4.5 g/L or 25 mM) and normoxia, a larger bovine caudal disc (Cd1-2 to Cd3-4) had a central concentration of ~2.6 %O2, ~8 mM of glucose and a pH value of 6.7, while the smallest caudal discs investigated (Cd6-7 and Cd7-8), had a central concentration of ~6.5 %O2, ~12 mM of glucose and a pH value of 6.9. DISCUSSION This work advances the knowledge of ex vivo disc culture microenvironments and highlights a critical need for optimization and standardization of culturing conditions. CONCLUSION Ultimately, for assessment of cell-based therapies and successful clinical translation based on nutritional demands, it is imperative that the critical metabolite values within organ cultures (minimum glucose, oxygen and pH values) are physiologically relevant and comparable to the stages of human degeneration.
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Affiliation(s)
- Emily E. McDonnell
- Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College DublinThe University of DublinDublinIreland
- Discipline of Mechanical, Manufacturing and Biomedical Engineering, School of Engineering, Trinity College DublinThe University of DublinDublinIreland
| | - Conor T. Buckley
- Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College DublinThe University of DublinDublinIreland
- Discipline of Mechanical, Manufacturing and Biomedical Engineering, School of Engineering, Trinity College DublinThe University of DublinDublinIreland
- Advanced Materials and Bioengineering Research (AMBER) Centre, Royal College of Surgeons in Ireland and Trinity College DublinThe University of DublinDublinIreland
- Tissue Engineering Research Group, Department of Anatomy and Regenerative MedicineRoyal College of Surgeons in IrelandDublinIreland
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18
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Hassan CR, Lee W, Komatsu DE, Qin YX. Evaluation of nucleus pulposus fluid velocity and pressure alteration induced by cartilage endplate sclerosis using a poro-elastic finite element analysis. Biomech Model Mechanobiol 2020; 20:281-291. [PMID: 32949306 DOI: 10.1007/s10237-020-01383-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 09/01/2020] [Indexed: 11/25/2022]
Abstract
The nucleus pulposus (NP) in the intervertebral disk (IVD) depends on diffusive fluid transport for nutrients through the cartilage endplate (CEP). Disruption in fluid exchange of the NP is considered a cause of IVD degeneration. Furthermore, CEP calcification and sclerosis are hypothesized to restrict fluid flow between the NP and CEP by decreasing permeability and porosity of the CEP matrix. We performed a finite element analysis of an L3-L4 lumbar functional spine unit with poro-elastic constitutive equations. The aim of the study was to predict changes in the solid and fluid parameters of the IVD and CEP under structural changes in CEP. A compressive load of 500 N was applied followed by a 10 Nm moment in extension, flexion, lateral bending, and axial rotation to the L3-L4 model with fully saturated IVD, CEP, and cancellous bone. A healthy case of L3-L4 physiology was then compared to two cases of CEP sclerosis: a calcified cartilage endplate and a fluid constricted sclerotic cartilage endplate. Predicted NP fluid velocity increased for the calcified CEP and decreased for the calcified + less permeable CEP. Decreased NP fluid velocity was prominent in the axial direction through the CEP due to a less permeable path available for fluid flux. Fluid pressure and maximum principal stress in the NP were predicted to increase in both cases of CEP sclerosis compared to the healthy case. The porous medium predictions of this analysis agree with the hypothesis that CEP sclerosis decreases fluid flow out of the NP, builds up fluid pressure in the NP, and increases the stress concentrations in the NP solid matrix.
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Affiliation(s)
- Chaudhry Raza Hassan
- Department of Biomedical Engineering, Stony Brook University, 215 Bioengineering Building, Stony Brook, NY, 11794, USA
| | - Wonsae Lee
- Department of Biomedical Engineering, Stony Brook University, 215 Bioengineering Building, Stony Brook, NY, 11794, USA
| | - David Edward Komatsu
- Department of Orthopaedics, School of Medicine, Stony Brook University, Stony Brook, NY, USA
| | - Yi-Xian Qin
- Department of Biomedical Engineering, Stony Brook University, 215 Bioengineering Building, Stony Brook, NY, 11794, USA.
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19
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Yin X, Motorwala A, Vesvoranan O, Levene HB, Gu W, Huang CY. Effects of Glucose Deprivation on ATP and Proteoglycan Production of Intervertebral Disc Cells under Hypoxia. Sci Rep 2020; 10:8899. [PMID: 32483367 PMCID: PMC7264337 DOI: 10.1038/s41598-020-65691-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Accepted: 03/05/2020] [Indexed: 12/25/2022] Open
Abstract
As the most common cause of low back pain, the cascade of intervertebral disc (IVD) degeneration is initiated by the disappearance of notochordal cells and progressive loss of proteoglycan (PG). Limited nutrient supply in the avascular disc environment restricts the production of ATP which is an essential energy source for cell survival and function such as PG biosynthesis. The objective of this study was to examine ATP level and PG production of porcine IVD cells under prolonged exposure to hypoxia with physiological glucose concentrations. The results showed notochordal NP and AF cells responded differently to changes of oxygen and glucose. Metabolic activities (including PG production) of IVD cells are restricted under the in-vivo nutrient conditions while NP notochordal cells are likely to be more vulnerable to reduced nutrition supply. Moreover, provision of energy, together or not with genetic regulation, may govern PG production in the IVD under restricted nutrient supply. Therefore, maintaining essential levels of nutrients may reduce the loss of notochordal cells and PG in the IVD. This study provides a new insight into the metabolism of IVD cells under nutrient deprivation and the information for developing treatment strategies for disc degeneration.
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Affiliation(s)
- Xue Yin
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA
| | - Aarif Motorwala
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA
| | - Oraya Vesvoranan
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA
| | - Howard B Levene
- Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Weiyong Gu
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA.,Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL, USA
| | - Chun-Yuh Huang
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA.
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20
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Cai XY, Sun MS, Huang YP, Liu ZX, Liu CJ, Du CF, Yang Q. Biomechanical Effect of L 4 -L 5 Intervertebral Disc Degeneration on the Lower Lumbar Spine: A Finite Element Study. Orthop Surg 2020; 12:917-930. [PMID: 32476282 PMCID: PMC7307239 DOI: 10.1111/os.12703] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/03/2020] [Accepted: 04/22/2020] [Indexed: 12/20/2022] Open
Abstract
OBJECTIVE To ascertain the biomechanical effects of a degenerated L4 -L5 segment on the lower lumbar spine through a comprehensive simulation of disc degeneration. METHODS A three-dimensional nonlinear finite element model of a normal L3 -S1 lumbar spine was constructed and validated. This normal model was then modified such that three degenerated models with different degrees of degeneration (mild, moderate, or severe) at the L4 -L5 level were constructed. While experiencing a follower compressive load (500 N), hybrid moment loads were applied to all models to determine range of motion (ROM), intradiscal pressure (IDP), maximum von Mises stress in the annulus, maximum shear stress in the annulus, and facet joint force. RESULTS As the degree of disc degeneration increased, the ROM of the L4 -L5 degenerated segment declined dramatically in all postures (flexion: 5.79°-1.91°; extension: 5.53°-2.62°; right lateral bending: 4.47°-1.46°; left lateral bending: 4.86°-1.61°; right axial rotation: 2.69°-0.74°; left axial rotation: 2.69°-0.74°), while the ROM in adjacent segments increased (1.88°-8.19°). The largest percent decrease in motion of the L4 -L5 segment due to disc degeneration was in right axial rotation (75%), left axial rotation (69%), flexion (67%), right lateral bending (67%), left lateral bending right (67%), and extension (53%). The change in the trend of the IDP was the same as that of the ROM. Specifically, the IDP decreased (flexion: 0.592-0.09 MPa; extension: 0.678-0.334 MPa; right lateral bending: 0.498-0.205 MPa; left lateral bending: 0.523-0.272 MPa; right axial rotation: 0.535-0.246 MPa; left axial rotation: 0.53-0.266 MPa) in the L4 -L5 segment, while the IDP in adjacent segments increased (0.511-0.789 MPa). The maximum von Mises stress and maximum shear stress of the annulus in whole lumbar spine segments increased (L4 -L5 segment: 0.413-2.626 MPa and 0.412-2.783 MPa, respectively; adjacent segment of L4 -L5 : 0.356-1.493 MPa and 0.359-1.718 MPa, respectively) as degeneration of the disc progressively increased. There was no apparent regularity in facet joint force in the degenerated segment as the degree of disc degeneration increased. Nevertheless, facet joint forces in adjacent healthy segments increased as the degree of disc degeneration increased (extension: 49.7-295.3 N; lateral bending: 3.5-171.2 N; axial rotation: 140.2-258.8 N). CONCLUSION Degenerated discs caused changes in the motion and loading pattern of the degenerated segments and adjacent normal segments. The abnormal load and motion in the degenerated models risked accelerating degeneration in the adjacent normal segments. In addition, accurate simulation of degenerated facet joints is essential for predicting changes in facet joint loads following disc degeneration.
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Affiliation(s)
- Xin-Yi Cai
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, China.,National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, China
| | - Meng-Si Sun
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, China.,National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, China
| | - Yun-Peng Huang
- Department of Spine Surgery, The First Affiliated Hospital of Fujian Medical University, Fuzhou, Fujian, China
| | - Zi-Xuan Liu
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, China.,National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, China
| | - Chun-Jie Liu
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, China.,National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, China
| | - Cheng-Fei Du
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, China.,National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, China
| | - Qiang Yang
- Department of Spine Surgery, Tianjin Hospital, Tianjin, China
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21
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Jaworski LM, Kleinhans KL, Jackson AR. Effects of Oxygen Concentration and Culture Time on Porcine Nucleus Pulposus Cell Metabolism: An in vitro Study. Front Bioeng Biotechnol 2019; 7:64. [PMID: 31001527 PMCID: PMC6454860 DOI: 10.3389/fbioe.2019.00064] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 03/07/2019] [Indexed: 01/07/2023] Open
Abstract
Low back pain is a common ailment that affects millions of individuals each year and is linked to degeneration of the intervertebral discs in the spine. Intervertebral disc degeneration is known to result from an imbalance in anabolic and catabolic activity by disc cells. Due to the avascular nature of the intervertebral disc, oxygen deficiency may occur in the central nucleus pulposus (NP). The resulting hypoxia affects matrix regulation and energy metabolism of disc cells, although the mechanisms are not fully understood. This study investigates in vitro glucose consumption and gene expression by NP cells over time under varying oxygen tensions. Notochordal porcine NP cells were cultured in agarose discs at 21, 5, or 1% oxygen tension for 1, 5, or 10 days. The expression of 10 key matrix genes, as well as Brachyury (T), by NP cells was analyzed using RT-PCR. Glucose consumption was measured using a two-point method. Results show that culture time and oxygen tension significantly affect glucose consumption rates by porcine NP cells. There were also significant changes in T expression based on oxygen level and culture time. The 1% oxygen tension had a significantly higher T expression on day 10 than the other two groups, which may indicate a better maintenance of the notochordal phenotype. MMP 1 and 13 expression increased over time for all groups, while only the 5% group showed an increase over time for MMP 3. TIMP expression followed the direction of MMPs but to a lesser magnitude. Five percent and twenty-one percent oxygen tensions led to decreases in anabolic gene expression while 1% led to increases. Oxygen concentration and culture time significantly impacted glucose consumption rate and the gene expression of matrix regulatory genes with hypoxic conditions most accurately maintaining the proper NP phenotype. This information is valuable not only for understanding disc pathophysiology, but also for harnessing the potential of notochordal NP cells in therapeutic applications.
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Affiliation(s)
- Lukas M Jaworski
- Orthopaedic Biomechanics Laboratory, Department of Biomedical Engineering, University of Miami, Coral Gables, FL, United States
| | - Kelsey L Kleinhans
- Orthopaedic Biomechanics Laboratory, Department of Biomedical Engineering, University of Miami, Coral Gables, FL, United States
| | - Alicia R Jackson
- Orthopaedic Biomechanics Laboratory, Department of Biomedical Engineering, University of Miami, Coral Gables, FL, United States
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22
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Hu BW, Lv X, Chen SF, Shao ZW. Application of Finite Element Analysis for Investigation of Intervertebral Disc Degeneration: from Laboratory to Clinic. Curr Med Sci 2019; 39:7-15. [PMID: 30868485 DOI: 10.1007/s11596-019-1993-7] [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: 01/26/2018] [Revised: 09/06/2018] [Indexed: 01/06/2023]
Abstract
Due to the ethical concern and inability to detect inner stress distributions of intervertebral disc (IVD), traditional methods for investigation of intervertebral disc degeneration (IVDD) have significant limitations. Many researchers have demonstrated that finite element analysis (FEA) is an effective tool for the research of IVDD. However, the specific application of FEA for investigation of IVDD has not been systematically elucidated before. In the present review, we summarize the current finite element models (FEM) used for the investigation of IVDD, including the poroelastic nonlinear FEM, diffusive-reactive theory model and cell-activity coupled mechano-electrochemical theory model. We further elaborate the use of FEA for the research of IVDD pathogenesis especially for nutrition and biomechanics associated etiology, and the biological, biomechanical and clinical influences of IVDD. In addition, the application of FEA for evaluation and exploration of various treatments for IVDD is also elucidated. We conclude that FEA is an excellent technique for research of IVDD, which could be used to explore the etiology, biology and biomechanics of IVDD. In the future, FEA may help us to achieve the goal of individualized precision therapy.
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Affiliation(s)
- Bin-Wu Hu
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Xiao Lv
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Song-Feng Chen
- Department of Orthopaedic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Zeng-Wu Shao
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
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23
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CERROLAZA M, NIETO F, GONZÁLEZ Y. COMPUTATION OF THE DYNAMIC COMPRESSION EFFECTS IN SPINE DISCS USING INTEGRAL METHODS. J MECH MED BIOL 2018. [DOI: 10.1142/s0219519417501032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The computational modeling using integral methods of dynamic loading and its effects on the nutrients transport in spine discs is addressed in this work. The numerical simulation and analysis was carried out using the Boundary Element Method (BEM) and a 3D model (axisymmetric) of the disc. The boundary model was discretized using linear interpolated elements and a multi-region approach. Concentration and production of three nutrients as lactate, oxygen and glucose were obtained. The maximum lactate concentration was observed very close to the interface between the nucleus and the inner annulus. A relatively simple model discretized with 130 boundary elements yielded very similar results to these coming from more complex FEM-based models. The numerical efforts in the domain and boundary discretizations were optimized using the BEM. Our results are in good agreement with those obtained using with finite element-based models. As expected, the dynamic loading increased the oxygen–glucose consumption and the lactate production, thus leading to a poor oxygen–glucose concentration at the nucleus of the disc. All of that is a favorable environment for a disc degeneration mechanism to be developed.
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Affiliation(s)
- M. CERROLAZA
- International Center of Numerical Methods in Engineering, Polytechnic University of Catalonia, c/Gran Capitá s/n, 08034, Barcelona, Spain
| | - F. NIETO
- National Institute of Bioengineering, Central University of Venezuela, Caracas, Venezuela
| | - Y. GONZÁLEZ
- National Institute of Bioengineering, Central University of Venezuela, Caracas, Venezuela
- Faculty of Industrial Engineering, University of Guayaquil, Ecuador
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24
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Buckley CT, Hoyland JA, Fujii K, Pandit A, Iatridis JC, Grad S. Critical aspects and challenges for intervertebral disc repair and regeneration-Harnessing advances in tissue engineering. JOR Spine 2018; 1:e1029. [PMID: 30895276 PMCID: PMC6400108 DOI: 10.1002/jsp2.1029] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 06/30/2018] [Accepted: 07/02/2018] [Indexed: 02/06/2023] Open
Abstract
Low back pain represents the highest burden of musculoskeletal diseases worldwide and intervertebral disc degeneration is frequently associated with this painful condition. Even though it remains challenging to clearly recognize generators of discogenic pain, tissue regeneration has been accepted as an effective treatment option with significant potential. Tissue engineering and regenerative medicine offer a plethora of exploratory pathways for functional repair or prevention of tissue breakdown. However, the intervertebral disc has extraordinary biological and mechanical demands that must be met to assure sustained success. This concise perspective review highlights the role of the disc microenvironment, mechanical and clinical design considerations, function vs mimicry in biomaterial‐based and cell engineering strategies, and potential constraints for clinical translation of regenerative therapies for the intervertebral disc.
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Affiliation(s)
- Conor T Buckley
- Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute Trinity College Dublin, The University of Dublin Dublin Ireland.,School of Engineering, Trinity College Dublin The University of Dublin Dublin Ireland.,Advanced Materials and Bioengineering Research (AMBER) Centre Royal College of Surgeons in Ireland & Trinity College Dublin, The University of Dublin Dublin Ireland
| | - Judith A Hoyland
- Division of Cell Matrix Biology and Regenerative Medicine University of Manchester Manchester UK.,NIHR Manchester Musculoskeletal Biomedical Research Unit, Central Manchester Foundation Trust Manchester Academic Health Science Centre Manchester UK
| | - Kengo Fujii
- Leni & Peter W. May Department of Orthopaedics Icahn School of Medicine at Mount Sinai New York New York USA.,Department of Orthopaedic Surgery University of Tsukuba Tsukuba Japan
| | - Abhay Pandit
- Centre for Research in Medical Devices (CÚRAM) National University of Ireland Galway Ireland
| | - James C Iatridis
- Leni & Peter W. May Department of Orthopaedics Icahn School of Medicine at Mount Sinai New York New York USA
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De Geer CM. Intervertebral Disk Nutrients and Transport Mechanisms in Relation to Disk Degeneration: A Narrative Literature Review. J Chiropr Med 2018; 17:97-105. [PMID: 30166966 DOI: 10.1016/j.jcm.2017.11.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Revised: 11/18/2017] [Accepted: 11/20/2017] [Indexed: 12/26/2022] Open
Abstract
Objective The purpose of this paper was to review the literature regarding the mechanisms leading to degeneration in intervertebral disks and to discuss contributing mechanical and biological factors. Methods The inclusion criteria for the literature review were research studies conducted in the last 3 decades with free full-text available in English. Review articles and articles pertaining to temporomandibular joints and joints of the body other than the intervertebral disk were excluded. The following databases were searched: PubMed, EBSCOhost, and Google Scholar through September 9, 2016. Results A total of 57 articles were used in this review. Intervertebral disk cells require glucose for sustainability and oxygen to synthesize matrix components. Nutrients enter the disk via 2 vascular supply routes: capillary beds of end plates and the peripheral annulus fibrosus. Solute size, shape and charge, compression, and metabolic demand all influence the efficiency of nutrient transport, and alterations of any of these factors may have effects on nutrient transport and, potentially, disk degeneration. Conclusions Progressive nutrient transport disruptions may actively contribute in advancing the phases of degenerative disk disease. Such disruptions include dysfunctional loading and spinal position, lack of motion, high frequency loading, disk injury, aging, smoking, an acidic environment, and a lack of nutrient bioavailability.
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Quantifying Baseline Fixed Charge Density in Healthy Human Cartilage Endplate: A Two-point Electrical Conductivity Method. Spine (Phila Pa 1976) 2017; 42:E1002-E1009. [PMID: 28699925 PMCID: PMC5509527 DOI: 10.1097/brs.0000000000002061] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Regional measurements of fixed charge densities (FCDs) of healthy human cartilage endplate (CEP) using a two-point electrical conductivity approach. OBJECTIVE The aim of this study was to determine the FCDs at four different regions (central, lateral, anterior, and posterior) of human CEP, and correlate the FCDs with tissue biochemical composition. SUMMARY OF BACKGROUND DATA The CEP, a thin layer of hyaline cartilage on the cranial and caudal surfaces of the intervertebral disc, plays an irreplaceable role in maintaining the unique physiological mechano-electrochemical environment inside the disc. FCD, arising from the carboxyl and sulfate groups of the glycosaminoglycans (GAG) in the extracellular matrix of the disc, is a key regulator of the disc ionic and osmotic environment through physicochemical and electrokinetic effects. Although FCDs in the annulus fibrosus (AF) and nucleus pulposus (NP) have been reported, quantitative baseline FCD in healthy human CEP has not been reported. METHODS CEP specimens were regionally isolated from human lumbar spines. FCD and ion diffusivity were concurrently investigated using a two-point electrical conductivity method. Biochemical assays were used to quantify regional GAG and water content. RESULTS FCD in healthy human CEP was region-dependent, with FCD lowest in the lateral region (P = 0.044). Cross-region FCD was 30% to 60% smaller than FCD in NP, but similar to the AF and articular cartilage (AC). CEP FCD (average: 0.12 ± 0.03 mEq/g wet tissue) was correlated with GAG content (average: 31.24 ± 5.06 μg/mg wet tissue) (P = 0.005). In addition, the cross-region ion diffusivity in healthy CEP (2.97 ± 1.00 × 10 cm/s) was much smaller than the AF and NP. CONCLUSION Healthy human CEP acts as a biomechanical interface, distributing loads between the bony vertebral body and soft disc tissues and as a gateway impeding rapid solute diffusion through the disc. LEVEL OF EVIDENCE N/A.
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Yao Y, Deng Q, Sun C, Song W, Liu H, Zhou Y. A genome-wide analysis of the gene expression profiles and alternative splicing events during the hypoxia-regulated osteogenic differentiation of human cartilage endplate-derived stem cells. Mol Med Rep 2017; 16:1991-2001. [PMID: 28656244 PMCID: PMC5562021 DOI: 10.3892/mmr.2017.6846] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 04/25/2017] [Indexed: 12/20/2022] Open
Abstract
It has been hypothesized that intervertebral disc degeneration is initiated by degeneration of the cartilage endplate (CEP), which is characterized by cartilage ossification. CEP‑derived stem cells (CESCs), with the potential for chondro‑osteogenic differentiation, may be responsible for the balance between chondrification and ossification in the CEP. The CEP remains in an avascular and hypoxic microenvironment; the present study observed that hypoxia was able to markedly inhibit the osteogenic differentiation of CESCs. This tissue‑specific CESC differentiation in response to a hypoxic microenvironment was physiologically important for the prevention of ossification in the CEP. In order to study the hypoxia‑regulated mechanisms underlying osteogenic differentiation of CESCs, a Human Transcriptome Array 2.0 was used to detect differentially expressed genes (DEGs) and alternatively spliced genes (ASGs) during the osteogenic differentiation of CESCs under hypoxia, compared with those induced under normoxia. High‑throughput analysis of DEGs and ASGs demonstrated that genes in the complement pathway were enriched, which may be a potential mechanism underlying hypoxia inhibition of CESCs osteogenesis. The results of the present study may provide a basis for future mechanistic studies regarding gene expression levels and alternative splicing events during the hypoxia‑regulated inhibition of osteogenesis, which may be helpful in identifying targets for CEP degeneration therapy.
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Affiliation(s)
- Yuan Yao
- Department of Orthopedics, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China
| | - Qiyue Deng
- Department of Neurobiology, College of Basic Medical Sciences, Third Military Medical University, Chongqing 400038, P.R. China
| | - Chao Sun
- Department of Orthopedics, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China
| | - Weiling Song
- Department of Ophthalmology, Southwest Hospital, Third Military Medical University, Chongqing 400038, P.R. China
| | - Huan Liu
- Department of Orthopedics, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China
| | - Yue Zhou
- Department of Orthopedics, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China
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Enhancement of Energy Production of the Intervertebral Disc by the Implantation of Polyurethane Mass Transfer Devices. Ann Biomed Eng 2017; 45:2098-2108. [PMID: 28612187 DOI: 10.1007/s10439-017-1867-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 06/01/2017] [Indexed: 12/25/2022]
Abstract
Insufficient nutrient supply has been suggested to be one of the etiologies for intervertebral disc (IVD) degeneration. We are investigating nutrient transport into the IVD as a potential treatment strategy for disc degeneration. Most cellular activities in the IVD (e.g., cell proliferation and extracellular matrix production) are mainly driven by adenosine-5'-triphosphate (ATP) which is the main energy currency. The objective of this study was to investigate the effect of increased mass transfer on ATP production in the IVD by the implantation of polyurethane (PU) mass transfer devices. In this study, the porcine functional spine units were used and divided into intact, device and surgical groups. For the device and surgical groups, two puncture holes were created bilaterally at the dorsal side of the annulus fibrosus (AF) region and the PU mass transfer devices were only implanted into the holes in the device group. Surgical groups were observed for the effects of placing the holes through the AF only. After 7 days of culture, the surgical group exhibited a significant reduction in the compressive stiffness and disc height compared to the intact and device groups, whereas no significant differences were found in compressive stiffness, disc height and cell viability between the intact and device groups. ATP, lactate and the proteoglycan contents in the device group were significantly higher than the intact group. These results indicated that the implantation of the PU mass transfer device can promote the nutrient transport and enhance energy production without compromising mechanical and cellular functions in the disc. These results also suggested that compromise to the AF has a negative impact on the IVD and must be addressed when treatment strategies are considered. The results of this study will help guide the development of potential strategies for disc degeneration.
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An JL, Zhang W, Zhang J, Lian LC, Shen Y, Ding WY. Vitamin D improves the content of TGF-β and IGF-1 in intervertebral disc of diabetic rats. Exp Biol Med (Maywood) 2017; 242:1254-1261. [PMID: 28537499 DOI: 10.1177/1535370217707744] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVE The contents of transforming growth factor-β and insulin-like growth factor-1 in disc of diabetic rats were measured at three different periods after injected with 1,25-Dihydroxyvitamin D3, and compared with that in normal rats. The significance of content changes was also discussed. METHODS Fourty-five Sprague-Dawley (SD) rats were divided into three groups, namely the experimental group (STZ+calcitriol), control group (STZ+citrate buffer), and normal group (citrate buffer). Complete lumbar discs in these groups were obtained at the second, fourth, sixth week, respectively. After paraffin-embedded sections and HE staining, the structure and morphology changes of disc were observed. The content of transforming growth factor-β and insulin-like growth factor-1 was measured by immunohistochemical method, and the expression of transforming growth factor-β and insulin-like growth factor-1 was detected by Western Blot. RESULTS In hematoxylin-eosin staining, degenerative changes were observed in disc of experimental and control group at three different periods, and there were no changes in disc in normal group. Immunohistochemical method indicated the content of transforming growth factor-β and insulin-like growth factor-1 in experimental and control group was significantly lower than normal group at three different periods ( P < 0.05). And there were significant differences between experimental and control group at three different periods ( P < 0.05). CONCLUSION Vitamin D can protect the degeneration of intervertebral disc and improve the content of transforming growth factor-β and insulin-like growth factor-1 in the intervertebral disc, which provides a new idea for the prevention and treatment of degenerative changes of the intervertebral disc in diabetic patients. Impact statement No researchers reported Vitamin D could protect degeneration of intervertebral disc. That is to say, we found a new method to prevent and treat degenerative changes of the intervertebral disc in diabetic patients. And Vitamin D prevented the discs by improving the content of TGF-β and IGF-1.
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Affiliation(s)
- Ji-Long An
- Department of Spine Surgery, The Third Hospital of Hebei Medical University, Shijiazhuang 050051, China
| | - Wei Zhang
- Department of Spine Surgery, The Third Hospital of Hebei Medical University, Shijiazhuang 050051, China
| | - Jian Zhang
- Department of Spine Surgery, The Third Hospital of Hebei Medical University, Shijiazhuang 050051, China
| | - Li-Chao Lian
- Department of Spine Surgery, The Third Hospital of Hebei Medical University, Shijiazhuang 050051, China
| | - Yong Shen
- Department of Spine Surgery, The Third Hospital of Hebei Medical University, Shijiazhuang 050051, China
| | - Wen-Yuan Ding
- Department of Spine Surgery, The Third Hospital of Hebei Medical University, Shijiazhuang 050051, China
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Xiao L, Xu HG, Wang H, Liu P, Liu C, Shen X, Zhang T, Xu YM. Intermittent Cyclic Mechanical Tension Promotes Degeneration of Endplate Cartilage via the Nuclear Factor-κB Signaling Pathway: an in Vivo Study. Orthop Surg 2017; 8:393-9. [PMID: 27627724 DOI: 10.1111/os.12260] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 06/28/2016] [Indexed: 12/13/2022] Open
Abstract
OBJECTIVE To establish a rabbit model for investigating the effects of intermittent cyclic mechanical tension (ICMT) on promoting degeneration of endplate cartilage. METHODS Forty New Zealand white rabbits were subjected to surgery and randomly divided into three equal groups as follows: control group (no treatment, n = 10), sham group (animals underwent a sham operation but were not subjected to mechanical tensile strain, n = 15) and loaded group (discs were subjected to 1.5 MPa external tensile loading by using an external loading device during the animals' daily activity, n = 15). Mechanical tensile strain was applied for 8 h/d. The animals were examined radiologically after 8 weeks treatment and then killed for removal of endplate cartilage tissue samples from their spines. Histological staining was performed to examine the morphology of endplate cartilage tissue. Multiple strategies were employed to examine degeneration of endplate cartilage and nuclear factor (NF)-κB signaling pathway activation. RESULTS After ICMT loading for 56 days, radiology revealed ossification, hyperosteogeny and stenosis in the intervertebral spaces. Examination of hematoxylin and eosin staining of sections of endplate cartilage showed significant damage as the load duration increased in the ICMT loading group. Expression of aggrecan (ACAN), type II collagen (COL-2A), SRY-related high mobility group-box gene 9 (SOX9) was down-regulated (FACAN = 21.515, P < 0.01; FCOL-2A = 6.670, P = 0.05; FSOX9 = 7.888, P < 0.05), whereas that of matrix metallopeptidase 13 (MMP13) was up-regulated (FMMP13 = 14.120, P < 0.01) after ICMT. Western blot and immunofluorescence revealed that expression of protein was consistent with gene expression results. Additionally, ICMT loading can lead to NF-κB signaling pathway activation as well as degeneration of endplate cartilage. CONCLUSION These experiments indicate that ICMT contributes to the activation of NF-κB signaling pathway in vivo and that the NF-κB signaling pathway further up-regulates MMP13, leading to degeneration of endplate cartilage.
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Affiliation(s)
- Liang Xiao
- Department of Orthopaedic Surgery, Yijishan Hospital, Wannan Medical College, Wuhu, China
| | - Hong-Guang Xu
- Department of Orthopaedic Surgery, Yijishan Hospital, Wannan Medical College, Wuhu, China.
| | - Hong Wang
- Department of Orthopaedic Surgery, Yijishan Hospital, Wannan Medical College, Wuhu, China
| | - Ping Liu
- Department of Orthopaedic Surgery, Yijishan Hospital, Wannan Medical College, Wuhu, China
| | - Chen Liu
- Department of Orthopaedic Surgery, Yijishan Hospital, Wannan Medical College, Wuhu, China
| | - Xiang Shen
- Department of Orthopaedic Surgery, Yijishan Hospital, Wannan Medical College, Wuhu, China
| | - Tao Zhang
- Department of Orthopaedic Surgery, Yijishan Hospital, Wannan Medical College, Wuhu, China
| | - Yong-Ming Xu
- Department of Orthopaedic Surgery, Yijishan Hospital, Wannan Medical College, Wuhu, China
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Wu Y, Cisewski SE, Wegner N, Zhao S, Pellegrini VD, Slate EH, Yao H. Region and strain-dependent diffusivities of glucose and lactate in healthy human cartilage endplate. J Biomech 2016; 49:2756-2762. [PMID: 27338525 DOI: 10.1016/j.jbiomech.2016.06.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 06/02/2016] [Accepted: 06/07/2016] [Indexed: 01/20/2023]
Abstract
The cartilage endplate (CEP) is implicated as the main pathway of nutrient supply to the healthy human intervertebral disc (IVD). In this study, the diffusivities of nutrient/metabolite solutes in healthy CEP were assessed, and further correlated with tissue biochemical composition and structure. The CEPs from non-degenerated human IVD were divided into four regions: central, lateral, anterior, and posterior. The diffusivities of glucose and lactate were measured with a custom diffusion cell apparatus under 0%, 10%, and 20% compressive strains. Biochemical assays were conducted to quantify the water and glycosaminoglycan (GAG) contents. The Safranin-O and Ehrlich׳s hematoxylin and eosin staining and scanning electron microscopy (SEM) were performed to reveal the tissue structure of the CEP. Average diffusivities of glucose and lactate in healthy CEP were 2.68±0.93×10-7cm2/s and 4.52±1.47×10-7cm2/s, respectively. Solute diffusivities were region-dependent (p<0.0001) with the highest values in the central region, and mechanical strains impeded solute diffusion in the CEP (p<0.0001). The solute diffusivities were significantly correlated with the tissue porosities (glucose: p<0.0001, r=0.581; lactate: p<0.0001, r=0.534). Histological and SEM studies further revealed that the collagen fibers in healthy CEP are more compacted than those in the nucleus pulposus (NP) and annulus fibrosus (AF) and show no clear orientation. Compared to human AF and NP, much smaller solute diffusivities in human CEP suggested that it acts as a gateway for solute diffusion through the disc, maintaining the balance of nutritional environment in healthy human disc under mechanical loading and preventing the progression of disc degeneration.
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Affiliation(s)
- Yongren Wu
- Department of Bioengineering, Clemson University, Clemson, SC, United States; Department of Orthopaedics, Medical University of South Carolina (MUSC), Charleston, SC, United States
| | - Sarah E Cisewski
- Department of Bioengineering, Clemson University, Clemson, SC, United States
| | - Nicholas Wegner
- Department of Bioengineering, Clemson University, Clemson, SC, United States
| | - Shichang Zhao
- Department of Bioengineering, Clemson University, Clemson, SC, United States
| | - Vincent D Pellegrini
- Department of Orthopaedics, Medical University of South Carolina (MUSC), Charleston, SC, United States
| | - Elizabeth H Slate
- Department of Statistics, Florida State University, Tallahassee, FL, United States
| | - Hai Yao
- Department of Bioengineering, Clemson University, Clemson, SC, United States; Department of Orthopaedics, Medical University of South Carolina (MUSC), Charleston, SC, United States.
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Zhang F, Zhao X, Shen H, Zhang C. Molecular mechanisms of cell death in intervertebral disc degeneration (Review). Int J Mol Med 2016; 37:1439-48. [PMID: 27121482 PMCID: PMC4866972 DOI: 10.3892/ijmm.2016.2573] [Citation(s) in RCA: 162] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 04/18/2016] [Indexed: 02/07/2023] Open
Abstract
Intervertebral discs (IVDs) are complex structures that consist of three parts, namely, nucleus pulposus, annulus fibrosus and cartilage endplates. With aging, IVDs gradually degenerate as a consequence of many factors, such as microenvironment changes and cell death. Human clinical trial and animal model studies have documented that cell death, particularly apoptosis and autophagy, significantly contribute to IVD degeneration. The mechanisms underlying this phenomenon include the activation of apoptotic pathways and the regulation of autophagy in response to nutrient deprivation and multiple stresses. In this review, we briefly summarize recent progress in understanding the function and regulation of apoptosis and autophagy signaling pathways. In particular, we focus on studies that reveal the functional mechanisms of these pathways in IVD degeneration.
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Affiliation(s)
- Fan Zhang
- Department of Orthopedics, Changhai Hospital Affiliated to The Second Military Medical University, Shanghai 200433, P.R. China
| | - Xueling Zhao
- Department of Orthopedics, The First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan 650032, P.R. China
| | - Hongxing Shen
- Department of Orthopedics, Changhai Hospital Affiliated to The Second Military Medical University, Shanghai 200433, P.R. China
| | - Caiguo Zhang
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
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Abstract
STUDY DESIGN Investigation of the effects of the impairment of different nutritional pathways on the intervertebral disc degeneration patterns in terms of spatial distributions of cell density, glycosaminoglycan content, and water content. OBJECTIVE The aim of this study was to test the hypothesis that impairment of different nutritional pathways would result in different degenerative patterns in human discs. SUMMARY OF BACKGROUND DATA Impairment of nutritional pathways has been found to affect cell viability in the disc. However, details on how impairment of different nutritional pathways affects the disc degeneration patterns are unknown. METHODS A 3D finite element model was used for this study. This finite element method was based on the cell-activity coupled mechano-electrochemical theory for cartilaginous tissues. Impairment of the nutritional pathways was simulated by lowering the nutrition level at the disc boundaries. Effects of the impartment of cartilaginous endplate-nucleus pulposus (CEP-NP) pathway only (Case 1), annulus fibrosus (AF) pathway only (Case 2), and both pathways (Case 3) on disc degeneration patterns were studied. RESULTS The predicted critical levels of nutrition for Case 1, Case 2, and Case 3 were around 30%, 20%, and 50% of the reference values, respectively. Below this critical level, the disc degeneration would occur. Disc degeneration appeared mainly in the NP for Case 1, in the outer AF for Case 2, and in both the NP and inner to middle AF for Case 3. For Cases 1 and 3, the loss of water content was primarily located in the mid-axial plane, which is consistent with the horizontal gray band seen in some T2-weighted magnetic resonance imaging (MRI). For the disc geometry used in this study, it was predicted that there existed a high-intensity zone (for Case 3), as seen in some T2-weighted MRI images. CONCLUSION Impairment of different nutrition pathways results in different degenerative patterns. LEVEL OF EVIDENCE N/A.
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DeLucca JF, Cortes DH, Jacobs NT, Vresilovic EJ, Duncan RL, Elliott DM. Human cartilage endplate permeability varies with degeneration and intervertebral disc site. J Biomech 2016; 49:550-7. [PMID: 26874969 DOI: 10.1016/j.jbiomech.2016.01.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 01/07/2016] [Accepted: 01/08/2016] [Indexed: 01/08/2023]
Abstract
Despite the critical functions the human cartilage endplate (CEP) plays in the intervertebral disc, little is known about its structural and mechanical properties and their changes with degeneration. Quantifying these changes with degeneration is important for understanding how the CEP contributes to the function and pathology of the disc. Therefore the objectives of this study were to quantify the effect of disc degeneration on human CEP mechanical properties, determine the influence of superior and inferior disc site on mechanics and composition, and simulate the role of collagen fibers in CEP and disc mechanics using a validated finite element model. Confined compression data and biochemical composition data were used in a biphasic-swelling model to calculate compressive extrafibrillar elastic and permeability properties. Tensile properties were obtained by applying published tensile test data to an ellipsoidal fiber distribution. Results showed that with degeneration CEP permeability decreased 50-60% suggesting that transport is inhibited in the degenerate disc. CEP fibers are organized parallel to the vertebrae and nucleus pulposus and may contribute to large shear strains (0.1-0.2) and delamination failure of the CEP commonly seen in herniated disc tissue. Fiber-reinforcement also reduces CEP axial strains thereby enhancing fluid flux by a factor of 1.8. Collectively, these results suggest that the structure and mechanics of the CEP may play critical roles in the solute transport and disc mechanics.
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Affiliation(s)
- John F DeLucca
- Department of Biomedical Engineering, University of Delaware, Newark, DE, United States
| | - Daniel H Cortes
- Department of Biomedical Engineering, University of Delaware, Newark, DE, United States
| | - Nathan T Jacobs
- Department of Mechanical Engineering, University of Pennsylvania, Philadelphia, PA, United States
| | - Edward J Vresilovic
- Penn State Hershey Bone and Joint Institute Pennsylvania State University, Hershey, PA, United States
| | - Randall L Duncan
- Department of Biomedical Engineering, University of Delaware, Newark, DE, United States; Department of Biological Sciences, University of Delaware, Newark, DE, United States
| | - Dawn M Elliott
- Department of Biomedical Engineering, University of Delaware, Newark, DE, United States.
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Yuan FL, Zhao MD, Jiang DL, Jin C, Liu HF, Xu MH, Hu W, Li X. Involvement of acid-sensing ion channel 1a in matrix metabolism of endplate chondrocytes under extracellular acidic conditions through NF-κB transcriptional activity. Cell Stress Chaperones 2016; 21:97-104. [PMID: 26384841 PMCID: PMC4679749 DOI: 10.1007/s12192-015-0643-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 09/01/2015] [Accepted: 09/04/2015] [Indexed: 01/01/2023] Open
Abstract
Acidic conditions are present in degenerated intervertebral discs and are believed to be responsible for matrix breakdown. Acid-sensing ion channel 1a (ASIC1a) is expressed in endplate chondrocytes, and its activation is associated with endplate chondrocyte apoptosis. However, the precise role of ASIC1a in regulating the matrix metabolic activity of endplate chondrocytes in response to extracellular acid remains poorly understood. Aggrecan (ACAN), type II collagen (Col2a1), and matrix metalloproteinase (MMP) expressions were determined using reverse transcription (RT)-PCR and Western blot. ASIC1a was knocked down by transfecting endplate chondrocytes with ASIC1a siRNA. MMP activity and NF-κB transcriptional activity were measured. NF-κB transcriptional activity was assessed by examining cytosolic phosphorylated IκBα and nuclear phosphorylated p65 levels. Extracellular acidic solution (pH 6.0) resulted in a decrease in ACAN and Co12a1 expressions and an increase in MMP-1, MMP-9, and MMP-13 expressions, as well as in MMP activity; while ASIC1a siRNA blocked these effects. In addition, acid-induced increase in cytosolic levels of phosphorylated IκBα and nuclear levels of phosphorylated p65 in endplate chondrocytes were inhibited by ASIC1a siRNA. ASIC1a is involved in matrix metabolism of endplate chondrocytes under extracellular acidic conditions via NF-κB transcriptional activity.
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Affiliation(s)
- Feng-Lai Yuan
- Department of Orthopaedics and Central Laboratory, The Third Hospital Affiliated to Nantong University, Wuxi, Jiangsu, 214041, China
| | - Ming-Dong Zhao
- Department of Orthopaedics, Jinshan Hospital, Fudan University, Shanghai, 201508, China.
| | - Dong-Lin Jiang
- Department of Orthopaedics and Central Laboratory, The Third Hospital Affiliated to Nantong University, Wuxi, Jiangsu, 214041, China
| | - Cheng Jin
- Department of Orthopaedics and Central Laboratory, The Third Hospital Affiliated to Nantong University, Wuxi, Jiangsu, 214041, China
| | - Hai-Fei Liu
- Department of Internal Medicine, The Affiliated Hospital of Medical College, Qingdao University, Qingdao, Shandong, 266100, China
| | - Ming-Hui Xu
- Department of Orthopaedics and Central Laboratory, The Third Hospital Affiliated to Nantong University, Wuxi, Jiangsu, 214041, China
| | - Wei Hu
- The Second Affiliated Hospital of Anhui Medical University, Hefei, 230601, Anhui, China
| | - Xia Li
- Department of Orthopaedics and Central Laboratory, The Third Hospital Affiliated to Nantong University, Wuxi, Jiangsu, 214041, China.
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O'Connell GD, Leach JK, Klineberg EO. Tissue Engineering a Biological Repair Strategy for Lumbar Disc Herniation. Biores Open Access 2015; 4:431-45. [PMID: 26634189 PMCID: PMC4652242 DOI: 10.1089/biores.2015.0034] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The intervertebral disc is a critical part of the intersegmental soft tissue of the spinal column, providing flexibility and mobility, while absorbing large complex loads. Spinal disease, including disc herniation and degeneration, may be a significant contributor to low back pain. Clinically, disc herniations are treated with both nonoperative and operative methods. Operative treatment for disc herniation includes removal of the herniated material when neural compression occurs. While this strategy may have short-term advantages over nonoperative methods, the remaining disc material is not addressed and surgery for mild degeneration may have limited long-term advantage over nonoperative methods. Furthermore, disc herniation and surgery significantly alter the mechanical function of the disc joint, which may contribute to progression of degeneration in surrounding tissues. We reviewed recent advances in tissue engineering and regenerative medicine strategies that may have a significant impact on disc herniation repair. Our review on tissue engineering strategies focuses on cell-based and inductive methods, each commonly combined with material-based approaches. An ideal clinically relevant biological repair strategy will significantly reduce pain and repair and restore flexibility and motion of the spine.
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Affiliation(s)
- Grace D. O'Connell
- Department of Mechanical Engineering, University of California, Berkeley, Berkeley, California
| | - J. Kent Leach
- Department of Biomedical Engineering, University of California, Davis, Davis, California
- Department of Orthopedic Surgery, University of California, Davis Medical Center, Davis, California
| | - Eric O. Klineberg
- Department of Orthopedic Surgery, University of California, Davis Medical Center, Davis, California
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Barthelemy VMP, van Rijsbergen MM, Wilson W, Huyghe JM, van Rietbergen B, Ito K. A computational spinal motion segment model incorporating a matrix composition-based model of the intervertebral disc. J Mech Behav Biomed Mater 2015; 54:194-204. [PMID: 26469631 DOI: 10.1016/j.jmbbm.2015.09.028] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 09/10/2015] [Accepted: 09/23/2015] [Indexed: 01/08/2023]
Abstract
The extracellular matrix of the intervertebral disc is subjected to changes with age and degeneration, affecting the biomechanical behaviour of the spine. In this study, a finite element model of a generic spinal motion segment that links spinal biomechanics and intervertebral disc biochemical composition was developed. The local mechanical properties of the tissue were described by the local matrix composition, i.e. fixed charge density, amount of water and collagen and their organisation. The constitutive properties of the biochemical constituents were determined by fitting numerical responses to experimental measurements derived from literature. This general multi-scale model of the disc provides the possibility to evaluate the relation between local disc biochemical composition and spinal biomechanics.
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Affiliation(s)
- V M P Barthelemy
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - M M van Rijsbergen
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - W Wilson
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - J M Huyghe
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - B van Rietbergen
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - K Ito
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
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Changes in perfusion and diffusion in the endplate regions of degenerating intervertebral discs: a DCE-MRI study. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2015; 24:2458-67. [PMID: 26238936 DOI: 10.1007/s00586-015-4172-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 07/29/2015] [Accepted: 07/29/2015] [Indexed: 10/23/2022]
Abstract
PURPOSE Dynamic contrast-enhanced MRI (DCE-MRI) was used to investigate the associations between intervertebral disc degeneration and changes in perfusion and diffusion in the disc endplates. METHODS 56 participants underwent MRI scans. Changes in DCE-MRI signal enhancement in the endplate regions were analyzed. Also, a group template was generated for the endplates and enhancement maps were registered to this template for group analysis. RESULTS DCE-MRI enhancement changed significantly in cranial endplates with increased degeneration. A similar trend was observed for caudal endplates, but it was not significant. Group-averaged enhancement maps revealed major changes in spatial distribution of endplate perfusion and diffusion with increasing disc degeneration especially in peripheral endplate regions. CONCLUSIONS Increased enhancement in the endplate regions of degenerating discs might be an indication of ongoing damage in these tissues. Therefore, DCE-MRI could aid in understanding the pathophysiology of disc degeneration. Moreover, it could be used in the planning of novel treatments such as stem cell therapy.
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Indian hedgehog contributes to human cartilage endplate degeneration. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2015; 24:1720-8. [PMID: 25958162 DOI: 10.1007/s00586-015-4000-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Revised: 05/03/2015] [Accepted: 05/03/2015] [Indexed: 10/23/2022]
Abstract
PURPOSE To determine the role of Indian hedgehog (Ihh) signaling in human cartilage endplate (CEP) degeneration. METHODS CEP-degenerated tissues from patients with Modic I or II changes (n = 9 and 45, respectively) and normal tissues from vertebral burst fracture patients (n = 17) were collected. Specimens were either cut into slices for organ culture ex vivo or digested to isolate chondrocytes for cell culture in vitro. Ihh expression and the effect of Ihh on cartilage degeneration were determined by investigating degeneration markers in this study. RESULTS Ihh expression and cartilage degeneration markers significantly increased in the Modic I and II groups. The expression of cartilage degeneration markers was positively correlated with degeneration severity. Gain-of-function for Ihh promoted expression of cartilage degeneration markers in vitro, while loss-of-function for Ihh inhibited their expression both in vitro and ex vivo. CONCLUSIONS These findings demonstrated that Ihh promotes CEP degeneration. Blocking Ihh pathway has potential clinical usage for attenuating CEP degeneration.
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Gullbrand SE, Peterson J, Mastropolo R, Roberts TT, Lawrence JP, Glennon JC, DiRisio DJ, Ledet EH. Low rate loading-induced convection enhances net transport into the intervertebral disc in vivo. Spine J 2015; 15:1028-33. [PMID: 25500262 DOI: 10.1016/j.spinee.2014.12.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 12/02/2014] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT The intervertebral disc primarily relies on trans-endplate diffusion for the uptake of nutrients and the clearance of byproducts. In degenerative discs, diffusion is often diminished by endplate sclerosis and reduced proteoglycan content. Mechanical loading-induced convection has the potential to augment diffusion and enhance net transport into the disc. The ability of convection to augment disc transport is controversial and has not been demonstrated in vivo. PURPOSE To determine if loading-induced convection can enhance small molecule transport into the intervertebral disc in vivo. STUDY DESIGN Net transport was quantified via postcontrast enhanced magnetic resonance imaging (MRI) into the discs of the New Zealand white rabbit lumbar spine subjected to in vivo cyclic low rate loading. METHODS Animals were administered the MRI contrast agent gadodiamide intravenously and subjected to in vivo low rate loading (0.5 Hz, 200 N) via a custom external loading apparatus for either 2.5, 5, 10, 15, or 20 minutes. Animals were then euthanized and the lumbar spines imaged using postcontrast enhanced MRI. The T1 constants in the nucleus, annulus, and cartilage endplates were quantified as a measure of gadodiamide transport into the loaded discs compared with the adjacent unloaded discs. Microcomputed tomography was used to quantify subchondral bone density. RESULTS Low rate loading caused the rapid uptake and clearance of gadodiamide in the nucleus compared with unloaded discs, which exhibited a slower rate of uptake. Relative to unloaded discs, low rate loading caused a maximum increase in transport into the nucleus of 16.8% after 5 minutes of loading. Low rate loading increased the concentration of gadodiamide in the cartilage endplates at each time point compared with unloaded levels. CONCLUSIONS Results from this study indicate that forced convection accelerated small molecule uptake and clearance in the disc induced by low rate mechanical loading. Low rate loading may, therefore, be therapeutic to the disc as it may enhance the nutrient uptake and waste product clearance.
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Affiliation(s)
| | - Joshua Peterson
- Rensselear Polytechnic Institute, 110 8th St, Troy, NY 12180, USA
| | | | | | - James P Lawrence
- Albany Medical College, 43 New Scotland Ave, Albany, NY 12208, USA
| | - Joseph C Glennon
- Veterinary Specialties, 1641 Main St, Pattersonville, NY 12137, USA
| | - Darryl J DiRisio
- Albany Medical College, 43 New Scotland Ave, Albany, NY 12208, USA
| | - Eric H Ledet
- Rensselear Polytechnic Institute, 110 8th St, Troy, NY 12180, USA.
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Hossain MS, Bergstrom DJ, Chen XB. Modelling and simulation of the chondrocyte cell growth, glucose consumption and lactate production within a porous tissue scaffold inside a perfusion bioreactor. ACTA ACUST UNITED AC 2014. [PMID: 28626683 PMCID: PMC5466199 DOI: 10.1016/j.btre.2014.12.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Mathematical and numerical modelling of the tissue culture process in a perfusion bioreactor is able to provide insight into the fluid flow, nutrients and wastes transport, dynamics of the pH value, and the cell growth rate. Knowing the complicated interdependence of these processes is essential for optimizing the culture process for cell growth. This paper presents a resolved scale numerical simulation, which allows one not only to characterize the supply of glucose inside a porous tissue scaffold in a perfusion bioreactor, but also to assess the overall culture condition and predict the cell growth rate. The simulation uses a simplified scaffold that consists of a repeatable unit composed of multiple strands. The simulation results explore some problematic regions inside the simplified scaffold where the concentration of glucose becomes lower than the critical value for the chondrocyte cell viability and the cell growth rate becomes significantly reduced.
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Affiliation(s)
- Md Shakhawath Hossain
- Mechanical Engineering Department, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada
| | - D J Bergstrom
- Mechanical Engineering Department, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada
| | - X B Chen
- Mechanical Engineering Department, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada
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Zhu Q, Gao X, Gu W. Temporal changes of mechanical signals and extracellular composition in human intervertebral disc during degenerative progression. J Biomech 2014; 47:3734-43. [PMID: 25305690 DOI: 10.1016/j.jbiomech.2014.09.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 08/27/2014] [Accepted: 09/03/2014] [Indexed: 01/08/2023]
Abstract
In this study, a three-dimensional finite element model was used to investigate the changes in tissue composition and mechanical signals within human lumbar intervertebral disc during the degenerative progression. This model was developed based on the cell-activity coupled mechano-electrochemical mixture theory. The disc degeneration was simulated by lowering nutrition levels at disc boundaries, and the temporal and spatial distributions of the fixed charge density, water content, fluid pressure, Von Mises stress, and disc deformation were analyzed. Results showed that fixed charge density, fluid pressure, and water content decreased significantly in the nucleus pulposus (NP) and the inner to middle annulus fibrosus (AF) regions of the degenerative disc. It was found that, with degenerative progression, the Von Mises stress (relative to that at healthy state) increased within the disc, with a larger increase in the outer AF region. Both the disc volume and height decreased with the degenerative progression. The predicted results of fluid pressure change in the NP were consistent with experimental findings in the literature. The knowledge of the variations of temporal and spatial distributions of composition and mechanical signals within the human IVDs provide a better understanding of the progression of disc degeneration.
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Affiliation(s)
- Qiaoqiao Zhu
- Tissue Biomechanics Lab, Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA
| | - Xin Gao
- Department of Mechanical and Aerospace Engineering, University of Miami, P.O. Box 248294, Coral Gables, FL, 33124-0624, USA
| | - Weiyong Gu
- Tissue Biomechanics Lab, Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA; Department of Mechanical and Aerospace Engineering, University of Miami, P.O. Box 248294, Coral Gables, FL, 33124-0624, USA.
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Malandrino A, Lacroix D, Hellmich C, Ito K, Ferguson SJ, Noailly J. The role of endplate poromechanical properties on the nutrient availability in the intervertebral disc. Osteoarthritis Cartilage 2014; 22:1053-60. [PMID: 24857972 DOI: 10.1016/j.joca.2014.05.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 04/15/2014] [Accepted: 05/07/2014] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To investigate the relevance of the human vertebral endplate poromechanics on the fluid and metabolic transport from and to the intervertebral disc (IVD) based on educated estimations of the poromechanical parameter values of the bony endplate (BEP). METHODS 50 micro-models of different BEP samples were generated from μCTs of lumbar vertebrae and allowed direct determination of porosity values. Permeability values were calculated by using the micro-models, through the simulation of permeation via computational fluid dynamics. These educated ranges of porosity and permeability values were used as inputs for mechano-transport simulations to assess their effect on both the distributions of metabolites within an IVD model and the poromechanical calculations within the cartilaginous part of the endplate i.e., the cartilage endplate (CEP). RESULTS BEP effective permeability was highly correlated to local variations of porosity (R(2) ≈ 0.88). Universal patterns between bone volume fraction and permeability arose from these results and from other experimental data in the literature. These variations in BEP permeability and porosity had negligible effects on the distributions of metabolites within the disc. In the CEP, the variability of the poromechanical properties of the BEP did not affect the predicted consolidation but induced higher fluid velocities. CONCLUSIONS The present paper provides the first sets of thoroughly identified BEP parameter values that can be further used in patient-specific poromechanical studies. Representing BEP structural changes through variations in poromechanical properties did not affect the diffusion of metabolites. However, attention might be paid to alterations in fluid velocities and cell mechano-sensing within the CEP.
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Affiliation(s)
- A Malandrino
- Biomechanics and Mechanobiology, Institute for Bioengineering of Catalonia, Barcelona, Spain
| | - D Lacroix
- INSIGNEO Institute for in silico Medicine, Department of Mechanical Engineering, University of Sheffield, Sheffield, UK
| | - C Hellmich
- Institute for Mechanics of Materials and Structures, Vienna University of Technology, Vienna, Austria
| | - K Ito
- Orthopedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - S J Ferguson
- Institute for Biomechanics, ETH, Zurich, Switzerland
| | - J Noailly
- Biomechanics and Mechanobiology, Institute for Bioengineering of Catalonia, Barcelona, Spain.
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Disc cell therapies: critical issues. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2014; 23 Suppl 3:S375-84. [PMID: 24509721 DOI: 10.1007/s00586-014-3177-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Revised: 12/02/2013] [Accepted: 01/08/2014] [Indexed: 12/13/2022]
Abstract
BACKGROUND Disc cell therapies, in which cells are injected into the degenerate disc in order to regenerate the matrix and restore function, appear to be an attractive, minimally invasive method of treatment. Interest in this area has stimulated research into disc cell biology in particular. However, other important issues, some of which are discussed here, need to be considered if cell-based therapies are to be brought to the clinic. PURPOSE Firstly, a question which is barely addressed in the literature, is how to identify patients with 'degenerative disc disease' who would benefit from cell therapy. Pain not disc degeneration is the symptom which drives patients to the clinic. Even though there are associations between back pain and disc degeneration, many people with even severely degenerate discs, with herniated discs or with spinal stenosis, are pain-free. It is not possible using currently available techniques to identify whether disc repair or regeneration would remove symptoms or prevent symptoms from occurring in future. Moreover, the repair process in human discs is very slow (years) because of the low cell density which can be supported nutritionally even in healthy human discs. If repair is necessary for relief of symptoms, questions regarding quality of life and rehabilitation during this long process need consideration. Also, some serious technical issues remain. Finding appropriate cell sources and scaffolds have received most attention, but these are not the only issues determining the feasibility of the procedure. There are questions regarding the safety of implanting cells by injection through the annulus whether the nutrient supply to the disc is sufficient to support implanted cells and whether, if cells are able to survive, conditions in a degenerate human disc will allow them to repair the damaged tissue. CONCLUSIONS If cell therapy for treatment of disc-related disorders is to enter the clinic as a routine treatment, investigations must examine the questions related to patient selection and the feasibility of achieving the desired repair in an acceptable time frame. Few diagnostic tests that examine whether cell therapies are likely to succeed are available at present, but definite exclusion criteria would be evidence of major disc fissures, or disturbance of nutrient pathways as measured by post-contrast MRI.
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Wu Y, Cisewski S, Sachs BL, Yao H. Effect of cartilage endplate on cell based disc regeneration: a finite element analysis. MOLECULAR & CELLULAR BIOMECHANICS : MCB 2013; 10:159-182. [PMID: 24015481 PMCID: PMC4315260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
This study examines the effects of cartilage endplate (CEP) calcification and the injection of intervertebral disc (IVD) cells on the nutrition distributions inside the human IVD under physiological loading conditions using multiphasic finite element modeling. The human disc was modeled as an inhomogeneous mixture consisting of a charged elastic solid, water, ions (Na+ and Cl-), and nutrient solute (oxygen, glucose and lactate) phases. The effect of the endplate calcification was simulated by a reduction of the tissue porosity (i.e., water volume faction) from 0.60 to 0.48. The effect of cell injection was simulated by increasing the cell density in the nucleus pulposus (NP) region by 50%, 100%, and 150%. Strain-dependent transport properties (e.g., hydraulic permeability and solute diffusivities) were considered to couple the solute transport and the mechanical loading. The simulation results showed that nutrient solute distribution inside the disc is maintained at a stable state during the day and night. The physiological diurnal cyclic loading does not change the nutrient environment in the human IVD. The cartilage endplate plays a significant role in the nutrient supply to human IVD. Calcification of the cartilage endplate significantly reduces the nutrient levels in human IVD. Therefore, in cell based therapy for IVD regeneration, the increased nutrient demand as a result of cell injection needs to be addressed. Excessive numbers of injected cells may cause further deterioration of the nutrient environment in the degenerated disc. This study is important for understanding the pathology of IVD degeneration and providing new insights into cell based therapies for low back pain.
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Affiliation(s)
- Yongren Wu
- Department of Bioengineering, Clemson University, Clemson, SC
| | - Sarah Cisewski
- Department of Bioengineering, Clemson University, Clemson, SC
| | - Barton L. Sachs
- Department of Orthopaedic Surgery, Medical University of South Carolina (MUSC), Charleston, SC
| | - Hai Yao
- Department of Bioengineering, Clemson University, Clemson, SC
- Department of Orthopaedic Surgery, Medical University of South Carolina (MUSC), Charleston, SC
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Sivakamasundari V, Lufkin T. Stemming the Degeneration: IVD Stem Cells and Stem Cell Regenerative Therapy for Degenerative Disc Disease. ACTA ACUST UNITED AC 2013; 2013. [PMID: 23951558 DOI: 10.5171/2013.724547] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The intervertebral disc (IVD) is immensely important for the integrity of vertebral column function. The highly specialized IVD functions to confer flexibility and tensile strength to the spine and endures various types of biomechanical force. Degenerative disc disease (DDD) is a prevalent musculoskeletal disorder and is the major cause of low back pain and includes the more severe degenerative lumbar scoliosis, disc herniation and spinal stenosis. DDD is a multifactorial disorder whereby an imbalance of anabolic and catabolic factors, or alterations to cellular composition, or biophysical stimuli and genetic background can all play a role in its genesis. However, our comprehension of IVD formation and theetiology of disc degeneration (DD) are far from being complete, hampering efforts to formulate appropriate therapies to tackle DD. Knowledge of the stem cells and various techniques to manipulate and direct them to particular fates have been promising in adopting a stem-cell based regenerative approach to DD. Moreover, new evidence on the residence of stem/progenitor cells within particular IVD niches has emerged holding promise for future therapeutic applications. Existing issues pertaining to current therapeutic approaches are also covered in this review.
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47
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Zhu Q, Jackson AR, Gu WY. Cell viability in intervertebral disc under various nutritional and dynamic loading conditions: 3d finite element analysis. J Biomech 2012; 45:2769-77. [PMID: 23040882 PMCID: PMC3593676 DOI: 10.1016/j.jbiomech.2012.08.044] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 07/30/2012] [Accepted: 08/31/2012] [Indexed: 12/23/2022]
Abstract
In this study, a new cell density model was developed and incorporated into the formulation of the mechano-electrochemical mixture theory to investigate the effects of deprivation of nutrition supply at boundary source, degeneration, and dynamic loading on the cell viability of intervertebral disc (IVD) using finite element methods. The deprivation of nutrition supply at boundary source was simulated by reduction in nutrition level at CEP and AF boundaries. Cases with 100%, 75%, 60%, 50% and 30% of normal nutrition level at both CEP and AF boundaries were modeled. Unconfined axial sinusoidal dynamic compressions with different combinations of amplitude (u=10%± 2.5%, ± 5%) and frequency (f=1, 10, 20 cycle/day) were applied. Degenerated IVD was modeled with altered material properties. Cell density decreased substantially with reduction of nutrition level at boundaries. Cell death was initiated primarily near the NP-AF interface on the mid-plane. Dynamic loading did not result in a change in the cell density in non-degenerated IVD, since glucose levels did not fall below the minimum value for cell survival; in degenerated IVDs, we found that increasing frequency and amplitude both resulted in higher cell density, because dynamic compression facilitates the diffusion of nutrients and thus increases the nutrition level around IVD cells. The novel computational model can be used to quantitatively predict both when and where cells start to die within the IVD under various kinds of nutritional and mechanical conditions.
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Affiliation(s)
- Qiaoqiao Zhu
- Tissue Biomechanics Laboratory, Department of Mechanical and Aerospace Engineering, College of Engineering, University of Miami, P.O. Box 248294, Coral Gables, FL 33124-0624, USA
| | - Alicia R. Jackson
- Orthopaedic Biomechanics Laboratory, Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA
| | - Wei Yong Gu
- Tissue Biomechanics Laboratory, Department of Mechanical and Aerospace Engineering, College of Engineering, University of Miami, P.O. Box 248294, Coral Gables, FL 33124-0624, USA
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Jackson AR, Huang CYC, Brown MD, Gu WY. 3D finite element analysis of nutrient distributions and cell viability in the intervertebral disc: effects of deformation and degeneration. J Biomech Eng 2012; 133:091006. [PMID: 22010741 DOI: 10.1115/1.4004944] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The intervertebral disc (IVD) receives important nutrients, such as glucose, from surrounding blood vessels. Poor nutritional supply is believed to play a key role in disc degeneration. Several investigators have presented finite element models of the IVD to investigate disc nutrition; however, none has predicted nutrient levels and cell viability in the disc with a realistic 3D geometry and tissue properties coupled to mechanical deformation. Understanding how degeneration and loading affect nutrition and cell viability is necessary for elucidating the mechanisms of disc degeneration and low back pain. The objective of this study was to analyze the effects of disc degeneration and static deformation on glucose distributions and cell viability in the IVD using finite element analysis. A realistic 3D finite element model of the IVD was developed based on mechano-electrochemical mixture theory. In the model, the cellular metabolic activities and viability were related to nutrient concentrations, and transport properties of nutrients were dependent on tissue deformation. The effects of disc degeneration and mechanical compression on glucose concentrations and cell density distributions in the IVD were investigated. To examine effects of disc degeneration, tissue properties were altered to reflect those of degenerated tissue, including reduced water content, fixed charge density, height, and endplate permeability. Two mechanical loading conditions were also investigated: a reference (undeformed) case and a 10% static deformation case. In general, nutrient levels decreased moving away from the nutritional supply at the disc periphery. Minimum glucose levels were at the interface between the nucleus and annulus regions of the disc. Deformation caused a 6.2% decrease in the minimum glucose concentration in the normal IVD, while degeneration resulted in an 80% decrease. Although cell density was not affected in the undeformed normal disc, there was a decrease in cell viability in the degenerated case, in which averaged cell density fell 11% compared with the normal case. This effect was further exacerbated by deformation of the degenerated IVD. Both deformation and disc degeneration altered the glucose distribution in the IVD. For the degenerated case, glucose levels fell below levels necessary for maintaining cell viability, and cell density decreased. This study provides important insight into nutrition-related mechanisms of disc degeneration. Moreover, our model may serve as a powerful tool in the development of new treatments for low back pain.
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Affiliation(s)
- Alicia R Jackson
- Tissue Biomechanics Lab, Department of Biomedical Engineering, University of Miami, Coral Gables, FL 33146, USA
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Comparison of four methods to simulate swelling in poroelastic finite element models of intervertebral discs. J Mech Behav Biomed Mater 2011; 4:1234-41. [PMID: 21783132 DOI: 10.1016/j.jmbbm.2011.04.008] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 04/06/2011] [Accepted: 04/11/2011] [Indexed: 11/22/2022]
Abstract
Osmotic phenomena influence the intervertebral disc biomechanics. Their simulation is challenging and can be undertaken at different levels of complexity. Four distinct approaches to simulate the osmotic behaviour of the intervertebral disc (a fixed boundary pore pressure model, a fixed osmotic pressure gradient model in the whole disc or only in the nucleus pulposus, and a swelling model with strain-dependent osmotic pressure) were analysed. Predictions were compared using a 3D poroelastic finite element model of a L4-L5 spinal unit under three different loading conditions: free swelling for 8 h and two daily loading cycles: (i) 200 N compression for 8 h followed by 500 N compression for 16 h; (ii) 500 N for 8 h followed by 1000 N for 16 h. Overall, all swelling models calculated comparable results, with differences decreasing under greater loads. Results predicted with the fixed boundary pore pressure and the fixed osmotic pressure in the whole disc models were nearly identical. The boundary pore pressure model, however, cannot simulate differential osmotic pressures in disc regions. The swelling model offered the best potential to provide more accurate results, conditional upon availability of reliable values for the required coefficients and material properties. Possible fields of application include mechanobiology investigations and crack opening and propagation. However, the other approaches are a good compromise between the ease of implementation and the reliability of results, especially when considering higher loads or when the focus is on global results such as spinal kinematics.
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