1
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Hayward S, Keogh PS, Miles AW, Gheduzzi S. The effect of structural changes on the low strain rate behaviour of the intervertebral disc. Proc Inst Mech Eng H 2024; 238:851-864. [PMID: 39180367 DOI: 10.1177/09544119241272915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/26/2024]
Abstract
The annuus fibrosus (AF) and nucleus pulposus (NP) of the intervertebral disc (IVD) work in conjunction to dissipate spinal loads. In this study we have isolated the contribution of the NP to the overall response of the disc and investigated the effect of extreme structural changes to the disc on the mechanical behaviour. Linear stiffness, overall load range, hysteresis area and total energy were used to evaluate the impact of these changes on the spine and surrounding structures. Six porcine lumbar isolated disc specimens were tested in 6 DOFs with a 400 N compressive axial preload at low strain rates in three conditions: intact (IN), after total nucleotomy (NN) and after the injection of bone cement into the nuclear void (SN). The latter two conditions, NN and SN, were chosen to emulate the effect of extreme changes to the NP on disc behaviour. When comparing with intact specimens, significant changes were noted primarily in axial compression-extension, mediolateral bending and flexion-extension. NN and SN cases demonstrated significant increases in linear stiffness, overall load range and total energy for mediolateral bending and flexion-extension compared to the intact (IN) state. SN also demonstrated a significant increase in total energy for axial compression-extension, and significant decreases in the elastic contribution to total energy in all axes except flexion-extension. These changes to total energy indicate that surrounding spinal structures would incur additional loading to produce the same motion in vivo after structural changes to the disc.
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Affiliation(s)
- Samantha Hayward
- Department of Mechanical Engineering, University of Bath, Bath, UK
| | - Patrick S Keogh
- Department of Mechanical Engineering, University of Bath, Bath, UK
| | - Anthony W Miles
- Department of Mechanical Engineering, University of Bath, Bath, UK
| | - Sabina Gheduzzi
- Department of Mechanical Engineering, University of Bath, Bath, UK
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Raftery K, Rahman T, Smith N, Schaer T, Newell N. The role of the nucleus pulposus in intervertebral disc recovery: Towards improved specifications for nucleus replacement devices. J Biomech 2024; 166:111990. [PMID: 38383232 DOI: 10.1016/j.jbiomech.2024.111990] [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: 06/07/2023] [Revised: 01/26/2024] [Accepted: 02/07/2024] [Indexed: 02/23/2024]
Abstract
Nucleus replacement devices (NRDs) have potential to treat degenerated or herniated intervertebral discs (IVDs). However, IVD height loss is a post-treatment complication. IVD height recovery involves the nucleus pulposus (NP), but the mechanism of this in response to physiological loads is not fully elucidated. This study aimed to characterise the non-linear recovery behaviour of the IVD in intact, post-nuclectomy, and post-NRD treatment states, under physiological loading. 36 bovine IVDs (12 intact, 12 post-nuclectomy, 12 post-treatment) underwent creep-recovery protocols simulating Sitting, Walking or Running, followed by 12 h of recovery. A rheological model decoupled the fluid-independent (elastic, fast) and fluid-dependent (slow) recovery phases. In post-nuclectomy and post-treatment groups, nuclectomy efficiency (ratio of NP removed to remaining NP) was quantified following post-test sectioning. Relative to intact, post-nuclectomy recovery significantly decreased in Sitting (-0.3 ± 0.4 mm, p < 0.05) and Walking (-0.6 ± 0.3 mm, p < 0.001) coupled with significant decreases to the slow response (p < 0.05). Post-nuclectomy, the fast and slow responses negatively correlated with nuclectomy efficiency (p < 0.05). In all protocols, the post-treatment group performed significantly worse in recovery (-0.5 ± 0.3 mm, p < 0.01) and the slow response (p < 0.05). Results suggest the NP mainly facilitates slow-phase recovery, linearly dependent on the amount of NP present. Failure of this NRD to recover is attributed to poor fluid imbibition. Additionally, unconfined NRD performance cannot be extrapolated to the in vitro response. This knowledge informs NRD design criteria to provide high osmotic pressure, and encourages testing standards to incorporate long-term recovery protocols.
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Affiliation(s)
- K Raftery
- Department of Bioengineering, Imperial College London, London, UK
| | - T Rahman
- Department of Bioengineering, Imperial College London, London, UK; Biomechanics Group, Department of Mechanical Engineering, Imperial College London, London, UK
| | - N Smith
- Division of Surgery and Interventional Science, University College London, Stanmore, UK
| | - T Schaer
- Department of Clinical Studies New Bolton Center, University of Pennsylvania School of Veterinary Medicine, Kennett Square, PA, USA
| | - N Newell
- Department of Bioengineering, Imperial College London, London, UK.
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3
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Sun Z, Sun Y, Mi C. Comprehensive modeling of annulus fibrosus: From biphasic refined characterization to damage accumulation under viscous loading. Acta Biomater 2024; 174:228-244. [PMID: 38070844 DOI: 10.1016/j.actbio.2023.12.007] [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: 09/06/2023] [Revised: 11/26/2023] [Accepted: 12/05/2023] [Indexed: 12/17/2023]
Abstract
The annulus fibrosus (AF), a permeable, hydrated, and fiber-reinforced soft tissue, exhibits complex responses influenced by fluid pressure, osmotic pressure, and structural mechanics. Existing models struggle to comprehensively represent these intricate interactions and the heterogeneous solid responses within the AF. Additionally, the mechanisms driving differential damage accumulation between non-degenerative and degenerative intervertebral discs remain poorly understood. In this study, we introduce a biphasic-swelling damage model for the AF. We conceptually develop and rigorously validate this model through tissue-level tests employing various loading modes, consistently aligning model predictions with experimental data. Leveraging parametric geometric algorithms and custom Python scripts, we construct models simulating both non-degenerative and degenerative discs. Following calibration, we subject these models to viscous loading protocols. Our findings reveal the posterior AF's susceptibility to damage, contingent upon loading rate and water content. We elucidate the underlying mechanisms by examining the temporal evolution of fluid pressure, osmotic pressure, and the regionally dependent fiber network. This research presents a highly accurate model of the AF, providing valuable insights into disc damage. Future research endeavors should expand this model to incorporate ionic transport and diffusion, enabling a more profound exploration of intervertebral disc mechanobiology. This comprehensive model contributes to a better understanding of AF behavior and may inform therapeutic strategies for disc-related pathologies. STATEMENT OF SIGNIFICANCE: This research presents a comprehensive model of the annulus fibrosus (AF), a crucial component of the intervertebral disc that provides structural support and resists deformation. The study introduces a biphasic-swelling damage model for the AF and validates it through tissue-level tests. The model accounts for fluid pressure, osmotic pressure, and matrix mechanics, providing a more accurate representation of the AF's behavior. The study also investigates the differential damage accumulation between non-degenerative and degenerative discs, shedding light on the mechanisms driving disc degeneration. The findings have significant implications for medical treatments and interventions, as they highlight the posterior AF's susceptibility to damage. This research is of great interest to readers interested in biomechanics, tissue engineering, and medical treatments for disc degeneration.
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Affiliation(s)
- Zhongwei Sun
- Jiangsu Key Laboratory of Engineering Mechanics, School of Civil Engineering, Southeast University, Nanjing, Jiangsu 210096, China
| | - Yueli Sun
- Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, Shanghai 200032, China
| | - Changwen Mi
- Jiangsu Key Laboratory of Engineering Mechanics, School of Civil Engineering, Southeast University, Nanjing, Jiangsu 210096, China.
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4
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Liu Q, Liang XF, Wang AG, Liu Y, Jia TJ, Li K, Zhang CQ. Failure mechanical properties of lumbar intervertebral disc under high loading rate. J Orthop Surg Res 2024; 19:15. [PMID: 38167031 PMCID: PMC10763340 DOI: 10.1186/s13018-023-04424-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 11/28/2023] [Indexed: 01/05/2024] Open
Abstract
BACKGROUND Lumbar disc herniation (LDH) is the main clinical cause of low back pain. The pathogenesis of lumbar disc herniation is still uncertain, while it is often accompanied by disc rupture. In order to explore relationship between loading rate and failure mechanics that may lead to lumbar disc herniation, the failure mechanical properties of the intervertebral disc under high rates of loading were analyzed. METHOD Bend the lumbar motion segment of a healthy sheep by 5° and compress it to the ultimate strength point at a strain rate of 0.008/s, making a damaged sample. Within the normal strain range, the sample is subjected to quasi-static loading and high loading rate at different strain rates. RESULTS For healthy samples, the stress-strain curve appears collapsed only at high rates of compression; for damaged samples, the stress-strain curves collapse both at quasi-static and high-rate compression. For damaged samples, the strengthening stage becomes significantly shorter as the strain rate increases, indicating that its ability to prevent the destruction is significantly reduced. For damaged intervertebral disc, when subjected to quasi-static or high rates loading until failure, the phenomenon of nucleus pulposus (NP) prolapse occurs, indicating the occurrence of herniation. When subjected to quasi-static loading, the AF moves away from the NP, and inner AF has the greatest displacement; when subjected to high rates loading, the AF moves closer to the NP, and outer AF has the greatest displacement. The Zhu-Wang-Tang (ZWT) nonlinear viscoelastic constitutive model was used to describe the mechanical behavior of the intervertebral disc, and the fitting results were in good agreement with the experimental curve. CONCLUSION Experimental results show that, both damage and strain rate have a significant effect on the mechanical behavior of the disc fracture. The research work in this article has important theoretical guiding significance for preventing LDH in daily life.
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Affiliation(s)
- Qing Liu
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, 300384, People's Republic of China
- National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, 300354, People's Republic of China
- Department of Mechanics, Tianjin University, Tianjin, 300354, People's Republic of China
- Tianjin Key Laboratory of Nonlinear Dynamics and Control, Tianjin, 300354, People's Republic of China
| | - Xiao-Feng Liang
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, 300384, People's Republic of China
- National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, 300354, People's Republic of China
| | - Ai-Guo Wang
- Affiliated Hospital of Tianjin Academia Sinica, Tianjin, 300120, People's Republic of China
| | - Ying Liu
- Affiliated Hospital of Tianjin Academia Sinica, Tianjin, 300120, People's Republic of China
| | - Tong-Ju Jia
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, 300384, People's Republic of China
- National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, 300354, People's Republic of China
| | - Kun Li
- Tianjin Key Laboratory of Film Electronic and Communication Device, Tianjin University of Technology, Tianjin, 300384, People's Republic of China.
| | - Chun-Qiu Zhang
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, 300384, People's Republic of China
- National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, 300354, People's Republic of China
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Gao Y, Chen X, Zheng G, Lin M, Zhou H, Zhang X. Current status and development direction of immunomodulatory therapy for intervertebral disk degeneration. Front Med (Lausanne) 2023; 10:1289642. [PMID: 38179277 PMCID: PMC10764593 DOI: 10.3389/fmed.2023.1289642] [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: 09/06/2023] [Accepted: 11/28/2023] [Indexed: 01/06/2024] Open
Abstract
Intervertebral disk (IVD) degeneration (IVDD) is a main factor in lower back pain, and immunomodulation plays a vital role in disease progression. The IVD is an immune privileged organ, and immunosuppressive molecules in tissues reduce immune cell (mainly monocytes/macrophages and mast cells) infiltration, and these cells can release proinflammatory cytokines and chemokines, disrupting the IVD microenvironment and leading to disease progression. Improving the inflammatory microenvironment in the IVD through immunomodulation during IVDD may be a promising therapeutic strategy. This article reviews the normal physiology of the IVD and its degenerative mechanisms, focusing on IVDD-related immunomodulation, including innate immune responses involving Toll-like receptors, NOD-like receptors and the complement system and adaptive immune responses that regulate cellular and humoral immunity, as well as IVDD-associated immunomodulatory therapies, which mainly include mesenchymal stem cell therapies, small molecule therapies, growth factor therapies, scaffolds, and gene therapy, to provide new strategies for the treatment of IVDD.
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Affiliation(s)
- Yanbing Gao
- Department of Orthopedics, Lanzhou University Second Hospital, Lanzhou, Gansu, China
- Key Laboratory of Bone and Joint Disease Research of Gansu Province, Lanzhou, Gansu, China
| | - Xiyue Chen
- Department of Orthopaedics, Sanya People’s Hospital, Sanya, Hainan, China
| | - Guan Zheng
- Department of Orthopedics, Lanzhou University Second Hospital, Lanzhou, Gansu, China
- Key Laboratory of Bone and Joint Disease Research of Gansu Province, Lanzhou, Gansu, China
| | - Maoqiang Lin
- Department of Orthopedics, Lanzhou University Second Hospital, Lanzhou, Gansu, China
- Key Laboratory of Bone and Joint Disease Research of Gansu Province, Lanzhou, Gansu, China
| | - Haiyu Zhou
- Department of Orthopedics, Lanzhou University Second Hospital, Lanzhou, Gansu, China
- Key Laboratory of Bone and Joint Disease Research of Gansu Province, Lanzhou, Gansu, China
| | - Xiaobo Zhang
- Department of Orthopaedics, Sanya People’s Hospital, Sanya, Hainan, China
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6
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Li ZL, Lu Q, Honiball JR, Wan SHT, Yeung KWK, Cheung KMC. Mechanical characterization and design of biomaterials for nucleus pulposus replacement and regeneration. J Biomed Mater Res A 2023; 111:1888-1902. [PMID: 37555381 DOI: 10.1002/jbm.a.37593] [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: 04/14/2023] [Accepted: 07/23/2023] [Indexed: 08/10/2023]
Abstract
Biomaterials for nucleus pulposus (NP) replacement and regeneration have great potential to restore normal biomechanics in degenerated intervertebral discs following nucleotomy. Mechanical characterizations are essential for assessing the efficacy of biomaterial implants for clinical applications. While traditional compression tests are crucial to quantify various modulus values, relaxation behaviors and fatigue resistance, rheological measurements should also be conducted to investigate the viscoelastic properties, injectability, and overall stability upon deformation. To recapitulate the physiological in vivo environment, the use of spinal models is necessary to evaluate the risk of implant extrusion and the restoration of biomechanics under different loading conditions. When designing devices for NP replacement, injectable materials are ideal to fully fill the nucleus cavity and prevent implant migration. In addition to achieving biocompatibility and desirable mechanical characteristics, biomaterial implants should be optimized to avoid implant extrusion or re-herniation post-operatively. This review discusses the most commonly used testing protocols for assessing mechanical properties of biomaterial implants and serves as reference material for enabling researchers to characterize NP implants through a unified approach whereby newly developed biomaterials may be compared and contrasted to existing devices.
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Affiliation(s)
- Zhuoqi Lucas Li
- Department of Orthopaedics & Traumatology, The University of Hong Kong, Hong Kong, China
| | - Qiuji Lu
- Department of Orthopaedics & Traumatology, The University of Hong Kong, Hong Kong, China
| | - John Robert Honiball
- Department of Orthopaedics & Traumatology, The University of Hong Kong, Hong Kong, China
| | - Sandra Hiu-Tung Wan
- Department of Orthopaedics & Traumatology, The University of Hong Kong, Hong Kong, China
| | - Kelvin Wai-Kwok Yeung
- Department of Orthopaedics & Traumatology, The University of Hong Kong, Hong Kong, China
- Shenzhen Key Laboratory for Innovative Technology in Orthopaedic Trauma, The University of Hong Kong Shenzhen Hospital, Shenzhen, China
| | - Kenneth Man-Chee Cheung
- Department of Orthopaedics & Traumatology, The University of Hong Kong, Hong Kong, China
- Department of Orthopaedics and Traumatology, The University of Hong Kong-Shenzhen Hospital, Shenzhen, China
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7
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Rahman T, Tavana S, Baxan N, Raftery KA, Morgan G, Schaer TP, Smith N, Moore A, Bull J, Stevens MM, Newell N. Quantifying internal intervertebral disc strains to assess nucleus replacement device designs: a digital volume correlation and ultra-high-resolution MRI study. Front Bioeng Biotechnol 2023; 11:1229388. [PMID: 37849982 PMCID: PMC10577660 DOI: 10.3389/fbioe.2023.1229388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 09/15/2023] [Indexed: 10/19/2023] Open
Abstract
Introduction: Nucleus replacement has been proposed as a treatment to restore biomechanics and relieve pain in degenerate intervertebral discs (IVDs). Multiple nucleus replacement devices (NRDs) have been developed, however, none are currently used routinely in clinic. A better understanding of the interactions between NRDs and surrounding tissues may provide insight into the causes of implant failure and provide target properties for future NRD designs. The aim of this study was to non-invasively quantify 3D strains within the IVD through three stages of nucleus replacement surgery: intact, post-nuclectomy, and post-treatment. Methods: Digital volume correlation (DVC) combined with 9.4T MRI was used to measure strains in seven human cadaveric specimens (42 ± 18 years) when axially compressed to 1 kN. Nucleus material was removed from each specimen creating a cavity that was filled with a hydrogel-based NRD. Results: Nucleus removal led to loss of disc height (12.6 ± 4.4%, p = 0.004) which was restored post-treatment (within 5.3 ± 3.1% of the intact state, p > 0.05). Nuclectomy led to increased circumferential strains in the lateral annulus region compared to the intact state (-4.0 ± 3.4% vs. 1.7 ± 6.0%, p = 0.013), and increased maximum shear strains in the posterior annulus region (14.6 ± 1.7% vs. 19.4 ± 2.6%, p = 0.021). In both cases, the NRD was able to restore these strain values to their intact levels (p ≥ 0.192). Discussion: The ability of the NRD to restore IVD biomechanics and some strain types to intact state levels supports nucleus replacement surgery as a viable treatment option. The DVC-MRI method used in the present study could serve as a useful tool to assess future NRD designs to help improve performance in future clinical trials.
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Affiliation(s)
- Tamanna Rahman
- Department of Bioengineering, Imperial College London, London, United Kingdom
- Department of Mechanical Engineering, Biomechanics Group, Imperial College London, London, United Kingdom
| | - Saman Tavana
- Department of Bioengineering, Imperial College London, London, United Kingdom
- Department of Mechanical Engineering, Biomechanics Group, Imperial College London, London, United Kingdom
| | - Nicoleta Baxan
- Biological Imaging Centre, Central Biomedical Services, Imperial College London, London, United Kingdom
- Faculty of Medicine, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Kay A. Raftery
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - George Morgan
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Thomas P. Schaer
- Department of Clinical Studies, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA, United States
| | - Nigel Smith
- Division of Surgery and Interventional Science, University College London, Stanmore, United Kingdom
| | - Axel Moore
- Department of Bioengineering, Imperial College London, London, United Kingdom
- Department of Materials and Institute of Biomedical Engineering, Imperial College London, London, United Kingdom
| | - Jonathan Bull
- Neurosurgery, BARTS Health NHS Trust, London, United Kingdom
| | - Molly M. Stevens
- Department of Bioengineering, Imperial College London, London, United Kingdom
- Department of Materials and Institute of Biomedical Engineering, Imperial College London, London, United Kingdom
| | - Nicolas Newell
- Department of Bioengineering, Imperial College London, London, United Kingdom
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8
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Lin J, Zheng X, Xiong Z, Xiang Q, Zhao Y, Jiang S, Sun Z, Fan D, Sun C, Li W. DJ-1-mediated p62 degradation delays intervertebral disc degeneration by inhibiting apoptosis of nucleus pulposus cells. Apoptosis 2023; 28:1357-1371. [PMID: 37300741 DOI: 10.1007/s10495-023-01862-0] [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] [Accepted: 05/30/2023] [Indexed: 06/12/2023]
Abstract
Intervertebral disc degeneration (IDD) is the most important pathological basis of degenerative spinal diseases, for which effective interventions are still lacking. Oxidative stress is considered to be one of the leading pathological mechanisms contributing to IDD. However, the exact role of DJ-1 as an essential member of the antioxidant defense system in IDD is still unclear. Therefore, the aim of this study was to investigate the role played by DJ-1 in IDD and to reveal its potential molecular mechanisms. Western blot and immunohistochemical staining assays were performed to detect the expression of DJ-1 in degenerative nucleus pulposus cells (NPCs). After overexpression of DJ-1 in NPCs by lentiviral transfection, DCFH-DA and MitoSOX fluorescent probes were used to evaluate the levels of reactive oxygen species (ROS); while western blot, TUNEL staining, and Caspase-3 activity were used to assess apoptosis. Immunofluorescence staining was used to demonstrate the relationship between DJ-1 and p62. After inhibition of lysosomal degradation function with chloroquine, p62 degradation and apoptosis in DJ-1 overexpressing NPCs were further examined. In vivo, we assessed the therapeutic effect of upregulated DJ-1 on IDD by X-ray, MRI and Safranin O-Fast green staining. The protein expression of DJ-1 was significantly decreased in degenerated NPCs, accompanied by increased apoptosis. However, overexpression of DJ-1 significantly inhibited the elevated ROS levels and apoptosis in NPCs under oxidative stress. Mechanistically, our results showed that upregulation of DJ-1 promoted p62 degradation via the autophagic lysosomal pathway and that the protective effect of DJ-1 on NPCs under oxidative stress was partially mediated by promoting lysosomal pathway degradation of p62. Moreover, intradiscal injection of adeno-associated virus for overexpression of DJ-1 mitigated the progression of IDD in rats. This study reveals that DJ-1 maintains the homeostasis of NPCs by promoting the degradation of p62 through the autophagic lysosomal pathway, suggesting that DJ-1 is a promising new target for IDD intervention.
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Affiliation(s)
- Jialiang Lin
- Department of Orthopaedics, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, China
- Beijing Key Laboratory of Spinal Disease Research, Beijing, China
- Engineering Research Center of Bone and Joint Precision Medicine, Ministry of Education, Beijing, China
- Peking University Health Science Center, Beijing, China
| | - Xuanqi Zheng
- Department of Orthopaedics, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, China
- Beijing Key Laboratory of Spinal Disease Research, Beijing, China
- Engineering Research Center of Bone and Joint Precision Medicine, Ministry of Education, Beijing, China
- Peking University Health Science Center, Beijing, China
| | - Zhencheng Xiong
- Trauma Medical Center, Department of Orthopedics Surgery, West China Hospital, West China Medical School, Sichuan University, Chengdu, China
| | - Qian Xiang
- Department of Orthopaedics, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, China
- Beijing Key Laboratory of Spinal Disease Research, Beijing, China
- Engineering Research Center of Bone and Joint Precision Medicine, Ministry of Education, Beijing, China
- Peking University Health Science Center, Beijing, China
| | - Yongzhao Zhao
- Department of Orthopaedics, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, China
- Beijing Key Laboratory of Spinal Disease Research, Beijing, China
- Engineering Research Center of Bone and Joint Precision Medicine, Ministry of Education, Beijing, China
- Peking University Health Science Center, Beijing, China
| | - Shuai Jiang
- Department of Orthopaedics, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, China
- Beijing Key Laboratory of Spinal Disease Research, Beijing, China
- Engineering Research Center of Bone and Joint Precision Medicine, Ministry of Education, Beijing, China
| | - Zhuoran Sun
- Department of Orthopaedics, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, China
- Beijing Key Laboratory of Spinal Disease Research, Beijing, China
- Engineering Research Center of Bone and Joint Precision Medicine, Ministry of Education, Beijing, China
| | - Dongwei Fan
- Department of Orthopaedics, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, China
- Beijing Key Laboratory of Spinal Disease Research, Beijing, China
- Engineering Research Center of Bone and Joint Precision Medicine, Ministry of Education, Beijing, China
| | - Chuiguo Sun
- Department of Orthopaedics, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, China
- Beijing Key Laboratory of Spinal Disease Research, Beijing, China
- Engineering Research Center of Bone and Joint Precision Medicine, Ministry of Education, Beijing, China
| | - Weishi Li
- Department of Orthopaedics, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, China.
- Beijing Key Laboratory of Spinal Disease Research, Beijing, China.
- Engineering Research Center of Bone and Joint Precision Medicine, Ministry of Education, Beijing, China.
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9
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Ao X, Li Y, Jiang T, Li C, Lian Z, Wang L, Zhang Z, Huang M. Angiopoietin-2 Promotes Mechanical Stress-induced Extracellular Matrix Degradation in Annulus Fibrosus Via the HIF-1α/NF-κB Signaling Pathway. Orthop Surg 2023; 15:2410-2422. [PMID: 37475697 PMCID: PMC10475680 DOI: 10.1111/os.13797] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 05/19/2023] [Accepted: 05/22/2023] [Indexed: 07/22/2023] Open
Abstract
OBJECTIVE Mechanical stress is an important risk factor for intervertebral disc degeneration (IVDD). Angiopoietin-2 (ANG-2) is regulated by mechanical stress and is widely involved in the regulation of extracellular matrix metabolism. In addition, the signaling cascade between HIF-1α and NF-κB is critical in matrix degradation. This study aims to investigate the role and molecular mechanism of ANG-2 in regulating the degeneration of annulus fibrosus (AF) through the HIF-1α/NF-κB signaling pathway. METHODS The bipedal standing mice IVDD model was constructed, and histological experiments were used to evaluate the degree of IVDD and the expression of ANG-2 in the AF. Mouse primary AF cells were extracted in vitro and subjected to mechanical stretching experiments. Western blot assay was used to detect the effect of mechanical stress on ANG-2, and the role of the ANG-2-mediated HIF-1α/NF-κB pathway in matrix degradation. In addition, the effect of inhibiting ANG-2 expression by siRNA or monoclonal antibody on delaying IVDD was investigated at in vitro and in vivo levels. One-way ANOVA with the least significant difference method was used for pairwise comparison of the groups with homogeneous variance, and Dunnett's method was used to compare the groups with heterogeneous variance. RESULTS In IVDD, the expressions of catabolic biomarkers (mmp-13, ADAMTS-4) and ANG-2 were significantly increased in AF. In addition, p65 expression was increased while HIF-1α expression was significantly decreased. The results of western blot assay showed mechanical stress significantly up-regulated the expression of ANG-2 in AF cells, and promoted matrix degradation by regulating the activity of HIF-1α/NF-κB pathway. Exogenous addition of Bay117082 and CoCl2 inhibited matrix degradation caused by mechanical stress. Moreover, injection of neutralizing antibody or treatment with siRNA to inhibit the expression of ANG-2 improved the matrix metabolism of AF and inhibited IVDD progression by regulating the HIF-1α/NF-κB signaling pathway. CONCLUSION In IVDD, mechanical stress could regulate the HIF-1α/NF-κB signaling pathway and matrix degradation by mediating ANG-2 expression in AF degeneration.
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Affiliation(s)
- Xiang Ao
- Division of Spine Surgery, Department of OrthopaedicsNanfang Hospital of Southern Medical UniversityGuangzhouGuangdongChina
| | - Yuan Li
- Department of Spine Surgery, Center for Orthopedic SurgeryThe Third Affiliated Hospital of Southern Medical UniversityGuangzhouGuangdongChina
- Academy of Orthopaedics·Guangdong ProvinceGuangzhouGuangdongChina
| | - Tao Jiang
- Division of Spine Surgery, Department of OrthopaedicsNanfang Hospital of Southern Medical UniversityGuangzhouGuangdongChina
| | - Chenglong Li
- Division of Spine Surgery, Department of OrthopaedicsNanfang Hospital of Southern Medical UniversityGuangzhouGuangdongChina
| | - Zhengnan Lian
- Department of Spine Surgery, Center for Orthopedic SurgeryThe Third Affiliated Hospital of Southern Medical UniversityGuangzhouGuangdongChina
- Academy of Orthopaedics·Guangdong ProvinceGuangzhouGuangdongChina
| | - Liang Wang
- Department of Spine Surgery, Center for Orthopedic SurgeryThe Third Affiliated Hospital of Southern Medical UniversityGuangzhouGuangdongChina
- Academy of Orthopaedics·Guangdong ProvinceGuangzhouGuangdongChina
| | - Zhongmin Zhang
- Division of Spine Surgery, Department of OrthopaedicsNanfang Hospital of Southern Medical UniversityGuangzhouGuangdongChina
| | - Minjun Huang
- Department of Spine Surgery, Center for Orthopedic SurgeryThe Third Affiliated Hospital of Southern Medical UniversityGuangzhouGuangdongChina
- Academy of Orthopaedics·Guangdong ProvinceGuangzhouGuangdongChina
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10
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Zavras AG, Dandu N, Espinoza-Orias AA, Singh K, An HS, Inoue N, Colman MW. Computed Tomography Osteoabsorptiometry Evaluation of Cervical Endplate Subchondral Bone Mineral Density. Global Spine J 2023; 13:1803-1811. [PMID: 34736350 PMCID: PMC10556913 DOI: 10.1177/21925682211050325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
STUDY DESIGN Basic Science. OBJECTIVE Poor subchondral bone mineral density (sBMD) has been linked with subsidence of cervical interbody devices or grafts, which are traditionally placed centrally on the endplates. Considering that sBMD reflects long-term stress distributions, we hypothesize that the cervical uncovertebral joints are denser than the central endplate region. This study sought to investigate density distributions using computed tomography osteoabsorptiometry (CT-OAM). METHODS Twelve human cervical spines from C3-C7 (60 vertebrae, 120 endplates) were imaged with CT and segmented to create 3D reconstructions. The superior and inferior endplates were isolated, and the sBMD of the whole endplate, endplate center, and uncus was evaluated using CT-OAM. Density distributions were compared across the subaxial cervical spine. RESULTS The uncinate region of the inferior and superior endplates was significantly denser than the central endplate across all vertebral levels (P < .01). When comparing sBMD of the whole inferior and superior endplates, the superior endplate was significantly denser than the inferior endplate (P < .0001). However, the inferior uncus was denser than the superior uncus (P = .035). When assessing sBMD by vertebral level, peak densities were observed at C4 and C5, while C7 was, on average, significantly less dense than all other vertebrae. CONCLUSION The subchondral bone of the cervical uncovertebral joints is significantly denser than the central endplates. While the superior endplate in its entirety is denser than the inferior endplate, the inverse was true for the uncovertebral joints. This study serves as a basis for future investigations of new implant designs and their implications on subsidence.
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Affiliation(s)
| | - Navya Dandu
- Rush University Medical Center, Chicago, IL, USA
| | | | - Kern Singh
- Rush University Medical Center, Chicago, IL, USA
| | - Howard S. An
- Rush University Medical Center, Chicago, IL, USA
| | - Nozomu Inoue
- Rush University Medical Center, Chicago, IL, USA
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11
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Chen JX, Li YH, Wen J, Li Z, Yu BS, Huang YC. Annular Defects Impair the Mechanical Stability of the Intervertebral Disc. Global Spine J 2023; 13:724-729. [PMID: 33783245 DOI: 10.1177/21925682211006061] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
STUDY DESIGN A biomechanical study. OBJECTIVES The purpose of this study was to investigate the effects of cruciform and square incisions of annulus fibrosus (AF) on the mechanical stability of bovine intervertebral disc (IVD) in multiple degrees of freedom. METHODS Eight bovine caudal IVD motion segments (bone-disc-bone) were obtained from the local abattoir. Cruciform and square incisions were made at the right side of the specimen's annulus using a surgical scalpel. Biomechanical testing of three-dimensional 6 degrees of freedom was then performed on the bovine caudal motion segments using the mechanical testing and simulation (MTS) machine. Force, displacement, torque and angle were recorded synchronously by the MTS system. P value <.05 was considered statistically significant. RESULTS Cruciform and square incisions of the AF reduced both axial compressive and torsional stiffness of the IVD and were significantly lower than those of the intact specimens (P < .01). Left-side axial torsional stiffness of the cruciform incision was significantly higher than a square incision (P < .01). Neither incision methods impacted flexional-extensional stiffness or lateral-bending stiffness. CONCLUSIONS The cruciform and square incisions of the AF obviously reduced axial compression and axial rotation, but they did not change the flexion-extension and lateral-bending stiffness of the bovine caudal IVD. This mechanical study will be meaningful for the development of new approaches to AF repair and the rehabilitation of the patients after receiving discectomy.
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Affiliation(s)
- Jun-Xin Chen
- Shenzhen Key Laboratory of Spine Surgery, Department of Spine Surgery, 74573Peking University Shenzhen Hospital, Shenzhen, China
- Shenzhen Engineering Laboratory of Orthopaedic Regenerative Technologies, National & Local Joint Engineering Research Center of Orthopaedic Biomaterials, 74573Peking University Shenzhen Hospital, Shenzhen, China
| | - Yun-He Li
- Shenzhen Key Laboratory of Spine Surgery, Department of Spine Surgery, 74573Peking University Shenzhen Hospital, Shenzhen, China
- Shenzhen Engineering Laboratory of Orthopaedic Regenerative Technologies, National & Local Joint Engineering Research Center of Orthopaedic Biomaterials, 74573Peking University Shenzhen Hospital, Shenzhen, China
| | - Jian Wen
- Shenzhen Key Laboratory of Spine Surgery, Department of Spine Surgery, 74573Peking University Shenzhen Hospital, Shenzhen, China
- Shenzhen Engineering Laboratory of Orthopaedic Regenerative Technologies, National & Local Joint Engineering Research Center of Orthopaedic Biomaterials, 74573Peking University Shenzhen Hospital, Shenzhen, China
| | - Zhen Li
- 161930AO Research Institute Davos, Davos, Switzerland
| | - Bin-Sheng Yu
- Shenzhen Key Laboratory of Spine Surgery, Department of Spine Surgery, 74573Peking University Shenzhen Hospital, Shenzhen, China
- Institute of Orthopaedics, Peking University Shenzhen Hospital, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen, China
| | - Yong-Can Huang
- Shenzhen Key Laboratory of Spine Surgery, Department of Spine Surgery, 74573Peking University Shenzhen Hospital, Shenzhen, China
- Shenzhen Engineering Laboratory of Orthopaedic Regenerative Technologies, National & Local Joint Engineering Research Center of Orthopaedic Biomaterials, 74573Peking University Shenzhen Hospital, Shenzhen, China
- Institute of Orthopaedics, Peking University Shenzhen Hospital, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen, China
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12
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Velnar T, Gradisnik L. Endplate role in the degenerative disc disease: A brief review. World J Clin Cases 2023; 11:17-29. [PMID: 36687189 PMCID: PMC9846967 DOI: 10.12998/wjcc.v11.i1.17] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 10/19/2022] [Accepted: 12/16/2022] [Indexed: 01/04/2023] Open
Abstract
The degenerative disease of the intervertebral disc is nowadays an important health problem, which has still not been understood and solved adequately. The vertebral endplate is regarded as one of the vital elements in the structure of the intervertebral disc. Its constituent cells, the chondrocytes in the endplate, may also be involved in the process of the intervertebral disc degeneration and their role is central both under physiological and pathological conditions. They main functions include a role in homeostasis of the extracellular environment of the intervertebral disc, metabolic support and nutrition of the discal nucleus and annulus beneath and the preservation of the extracellular matrix. Therefore, it is understandable that the cells in the endplate have been in the centre of research from several viewpoints, such as development, degeneration and growth, reparation and remodelling, as well as treatment strategies. In this article, we briefly review the importance of vertebral endplate, which are often overlooked, in the intervertebral disc degeneration.
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Affiliation(s)
- Tomaz Velnar
- Department of Neurosurgery, University Medical Centre Ljubljana, Ljubljana 1000, Slovenia
- Alma Mater Europaea Maribor, Maribor 2000, Slovenia
| | - Lidija Gradisnik
- Alma Mater Europaea Maribor, Maribor 2000, Slovenia
- Institute of Biomedical Sciences, University of Maribor, University of Maribor, Maribor 2000, Slovenia
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13
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Degenerative Disc Disease of the Spine: From Anatomy to Pathophysiology and Radiological Appearance, with Morphological and Functional Considerations. J Pers Med 2022; 12:jpm12111810. [PMID: 36579533 PMCID: PMC9698646 DOI: 10.3390/jpm12111810] [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: 10/05/2022] [Revised: 10/28/2022] [Accepted: 10/30/2022] [Indexed: 11/06/2022] Open
Abstract
Degenerative disc disease is a common manifestation in routine imaging of the spine; this finding is partly attributable to physiological aging and partly to a pathological condition, and sometimes this distinction is simply not clear. In this review, we start focusing on disc anatomy and pathophysiology and try to correlate them with radiological aspects. Furthermore, there is a special focus on degenerative disc disease terminology, and, finally, some considerations regarding disc morphology and its specific function, as well as the way in which these aspects change in degenerative disease. Radiologists, clinicians and spine surgeons should be familiar with these aspects since they have an impact on everyday clinical practice.
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14
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Lim S, Huff RD, Veres JE, Satish D, O'Connell GD. Disc geometry measurement methods affect reported compressive mechanics by up to 65. JOR Spine 2022; 5:e1214. [PMID: 36203862 PMCID: PMC9520764 DOI: 10.1002/jsp2.1214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/04/2022] [Accepted: 06/17/2022] [Indexed: 11/10/2022] Open
Abstract
Mechanical testing is a valuable tool for assessing intervertebral disc health, but the wide range of testing protocols makes it difficult to compare results from different studies. Normalizing mechanical properties by disc geometry allows for such comparisons, but there is little consistency in the methods by which disc geometry is measured. As such, we hypothesized that methods used to measure disc geometry would impact reported mechanical properties. Disc height and area were measured using computed tomography (CT), digital calipers, and ImageJ to yield three different measurements for disc height and six for disc area. Disc heights measured by digital calipers ex situ were >30% less than disc heights measured in situ by CT, and disc areas measured ex situ using ImageJ were >30% larger than those measured by CT. This significantly affected reported mechanical properties, leading to a 65% reduction in normalized compressive stiffness in the most extreme case. Though we cannot quantitatively correct between methods, results presented in this study suggest that disc geometry measurement methods have a significant impact on normalized mechanical properties and should be accounted for when comparing results.
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Affiliation(s)
- Shiyin Lim
- Department of Mechanical EngineeringUniversity of California, BerkeleyBerkeleyCaliforniaUSA
| | - Reece D. Huff
- Department of Mechanical EngineeringUniversity of California, BerkeleyBerkeleyCaliforniaUSA
| | - Joanna E. Veres
- Department of BioengineeringUniversity of California, BerkeleyBerkeleyCaliforniaUSA
| | - Divya Satish
- Department of BioengineeringUniversity of California, BerkeleyBerkeleyCaliforniaUSA
| | - Grace D. O'Connell
- Department of Mechanical EngineeringUniversity of California, BerkeleyBerkeleyCaliforniaUSA
- Department of Orthopaedic SurgeryUniversity of California, San FranciscoSan FranciscoCaliforniaUSA
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15
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Cyanidin attenuates the high hydrostatic pressure-induced degradation of cellular matrix of nucleus pulposus cell via blocking the Wnt/β-catenin signaling. Tissue Cell 2022; 76:101798. [DOI: 10.1016/j.tice.2022.101798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/29/2022] [Accepted: 04/08/2022] [Indexed: 11/20/2022]
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16
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The Endplate Role in Degenerative Disc Disease Research: The Isolation of Human Chondrocytes from Vertebral Endplate—An Optimised Protocol. Bioengineering (Basel) 2022; 9:bioengineering9040137. [PMID: 35447697 PMCID: PMC9029037 DOI: 10.3390/bioengineering9040137] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 03/12/2022] [Accepted: 03/23/2022] [Indexed: 12/27/2022] Open
Abstract
Background: Degenerative disc disease is a progressive and chronic disorder with many open questions regarding its pathomorphological mechanisms. In related studies, in vitro organ culture systems are becoming increasingly essential as a replacement option for laboratory animals. Live disc cells are highly appealing to study the possible mechanisms of intervertebral disc (IVD) degeneration. To study the degenerative processes of the endplate chondrocytes in vitro, we established a relatively quick and easy protocol for isolating human chondrocytes from the vertebral endplates. Methods: The fragments of human lumbar endplates following lumbar fusion were collected, cut, ground and partially digested with collagenase I in Advanced DMEM/F12 with 5% foetal bovine serum. The sediment was harvested, and cells were seeded in suspension, supplemented with special media containing high nutrient levels. Morphology was determined with phalloidin staining and the characterisation for collagen I, collagen II and aggrecan with immunostaining. Results: The isolated cells retained viability in appropriate laboratory conditions and proliferated quickly. The confluent culture was obtained after 14 days. Six to 8 h after seeding, attachments were observed, and proliferation of the isolated cells followed after 12 h. The cartilaginous endplate chondrocytes were stable with a viability of up to 95%. Pheno- and geno-typic analysis showed chondrocyte-specific expression, which decreased with passages. Conclusions: The reported cell isolation process is simple, economical and quick, allowing establishment of a viable long-term cell culture. The availability of a vertebral endplate cell model will permit the study of cell properties, biochemical aspects, the potential of therapeutic candidates for the treatment of disc degeneration, and toxicology studies in a well-controlled environment.
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17
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Jia H, Lin X, Wang D, Wang J, Shang Q, He X, Wu K, Zhao B, Peng P, Wang H, Wang D, Li P, Yang L, Luo Z, Yang L. Injectable hydrogel with nucleus pulposus-matched viscoelastic property prevents intervertebral disc degeneration. J Orthop Translat 2022; 33:162-173. [PMID: 35415072 PMCID: PMC8980713 DOI: 10.1016/j.jot.2022.03.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 03/10/2022] [Accepted: 03/16/2022] [Indexed: 02/07/2023] Open
Abstract
Background/Objective Intervertebral disc (IVD) degeneration (IVDD) that greatly affected by regional biomechanical environment is a major cause of low back pain. Injectable hydrogels have been commonly studied for treatment of IVDD due to their capability of mimicking extracellular matrix structure to support cellular behavior and clinical prospects in minimally invasive treatment. However, most hydrogels suffer from complicated chemistry, potential uncertainty and toxicity from in-situ gelation, and mismatch with IVD mechanical environment that limit their therapeutic effects or clinical translation in IVDD or intervertebral disc defect repair. For IVD lesion repair, the study aims to develop a novel hydrogel with shear-thinning enabled injectability, high bio-safety, and mechanical properties adaptable to the IVD environment, using a simple chemistry and method. And therapeutic efficacy of the novel hydrogel in the treatment of IVDD or intervertebral disc defect will be revealed. Methods A glycerol cross-linked PVA gel (GPG) was synthesized based on multiple H-bonds formation between glycerol molecules and PVA chains. The rheological and mechanical properties were tested. The swelling ratio was measured. The micro-architecture was observed through scanning and transmission electron microscopes. Nucleus pulposus (NP) cells were cultured in GPG-coated plates or silicone chambers treated under hydrostatic or dynamic loading in vitro, and examined for proliferation, vitality, apoptosis, expression of catabolic and anabolic markers. GPG was injected in needle puncture (IDD) or NP discectomy (NPD) models in vivo, and examined through magnetic resonance imaging, micro-computed tomography scanning and histological staining. Results GPG had a highly porous structure consisting of interconnected pores. Meanwhile, the GPG had NP-like viscoelastic property, and was able to withstand the cyclic deformation while exhibiting a prominent energy-dissipating capability. In vitro cell tests demonstrated that, the hydrogel significantly down-regulated the expression of catabolic markers, maintained the level of anabolic markers, preserved cell proliferation and vitality, reduced apoptotic rate of NP cells under pathologically hydrostatic and dynamic loading environments compared to cells cultured on untreated plate or silicone chamber. In vivo animal studies revealed that injection of GPG efficiently maintained NP structural integrity, IVD height and relative water content in IDD models, and stimulated the fibrous repair in NPD models. Conclusion This study showed that GPG, with high injectability, NP-like viscoelastic characteristics, good energy-dissipating properties and swelling capacities, preserved NP cells vitality against pathological loading, and had therapeutic effects on IVD repair in IDD and NPD models. The translational potential of this article Effective clinical strategy for treatment of intervertebral disc degeneration (IVDD) is still lacking. This study demonstrates that injection of a hydrogel with nucleus pulposus-matched viscoelastic property could remarkably prevent the IVDD progress. Prepared with simple chemistry and procedure, the cell/drug-free GPG with high bio-safety and shear-thinning enabled injectability bears great translational potential for the clinical treatment of IVDD via a minimally invasive approach.
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Affiliation(s)
- Haoruo Jia
- Institute of Orthopedic Surgery, The First Affiliated Hospital, Fourth Military Medical University, Xi'an, 710032, China
| | - Xiao Lin
- Orthopedic Institute and Department of Orthopedics, The First Affiliated Hospital, Soochow University, Suzhou, 215000, China
| | - Dong Wang
- Institute of Orthopedic Surgery, The First Affiliated Hospital, Fourth Military Medical University, Xi'an, 710032, China
| | - Jingwei Wang
- Department of Medicine Chemistry and Pharmaceutical Analysis, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, China
| | - Qiliang Shang
- Institute of Orthopedic Surgery, The First Affiliated Hospital, Fourth Military Medical University, Xi'an, 710032, China
| | - Xin He
- Department of Medicine Chemistry and Pharmaceutical Analysis, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, China
- Air Force Hospital of Eastern Theater Command, Nanjing, 210000, China
| | - Kang Wu
- Orthopedic Institute and Department of Orthopedics, The First Affiliated Hospital, Soochow University, Suzhou, 215000, China
| | - Boyan Zhao
- Department of Neurosurgery, The First Affiliated Hospital, Fourth Military Medical University, Xi'an, 710032, China
| | - Pandi Peng
- Institute of Flexible Electronics, Northwestern Polytechnical University, Xi'an, 710129, China
| | - Han Wang
- Institute of Orthopedic Surgery, The First Affiliated Hospital, Fourth Military Medical University, Xi'an, 710032, China
| | - Di Wang
- Institute of Orthopedic Surgery, The First Affiliated Hospital, Fourth Military Medical University, Xi'an, 710032, China
| | - Pan Li
- Institute of Orthopedic Surgery, The First Affiliated Hospital, Fourth Military Medical University, Xi'an, 710032, China
- Medical Research Institute, Northwestern Polytechnical University, Xi′an, 710032, China
| | - Liu Yang
- Institute of Orthopedic Surgery, The First Affiliated Hospital, Fourth Military Medical University, Xi'an, 710032, China
- Medical Research Institute, Northwestern Polytechnical University, Xi′an, 710032, China
| | - Zhuojing Luo
- Institute of Orthopedic Surgery, The First Affiliated Hospital, Fourth Military Medical University, Xi'an, 710032, China
- Medical Research Institute, Northwestern Polytechnical University, Xi′an, 710032, China
| | - Lei Yang
- Orthopedic Institute and Department of Orthopedics, The First Affiliated Hospital, Soochow University, Suzhou, 215000, China
- Center for Health Science and Engineering (CHSE), School of Health Sciences and Biomedical Engineering, Hebei University of Technology, Tianjin, 300130, China
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18
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Dixon AR, Warren JP, Culbert MP, Mengoni M, Wilcox RK. Review of in vitro mechanical testing for intervertebral disc injectable biomaterials. J Mech Behav Biomed Mater 2021; 123:104703. [PMID: 34365096 DOI: 10.1016/j.jmbbm.2021.104703] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 06/22/2021] [Accepted: 07/03/2021] [Indexed: 01/17/2023]
Abstract
Many early stage interventions for intervertebral disc degeneration are under development involving injection of a biomaterial into the affected tissue. Due to the complex mechanical behaviour of the intervertebral disc, there are challenges in comprehensively evaluating the performance of these injectable biomaterials in vitro. The aim of this review was to examine the different methods that have been developed to mechanically test injectable intervertebral disc biomaterials in an in vitro disc model. Testing methods were examined with emphasis on overall protocol, artificial degeneration method, mechanical testing regimes and injection delivery. Specifically, the effects of these factors on the evaluation of different aspects of device performance was assessed. Broad testing protocols varied between studies and enabled evaluation of different aspects of an injectable treatment. Studies employed artificial degeneration methodologies which were either on a macro scale through mechanical means or on a microscale with biochemical means. Mechanical loading regimes differed greatly across studies, with load being either held constant, ramped to failure, or applied cyclically, with large variability on all loading parameters. Evaluation of the risk of herniation was possible by utilising ramped loading, whereas cyclic loading enabled the examination of the restoration of mechanical behaviour for initial screening of biomaterials and surgical technique optimisation studies. However, there are large variations in the duration or tests, and further work is needed to define an appropriate number of cycles to standardise this type of testing. Biomaterial delivery was controlled by set volume or haptic feedback, and future investigations should generate evidence applying physiological loading during injection and normalisation of injection parameters based on disc size. Based on the reviewed articles and considering clinical risks, a series of recommendations have been made for future intervertebral disc mechanical testing.
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Affiliation(s)
- A R Dixon
- University of Leeds, Institute of Medical and Biological Engineering, Leeds, LS2 9JT, United Kingdom.
| | - J P Warren
- University of Leeds, Institute of Medical and Biological Engineering, Leeds, LS2 9JT, United Kingdom
| | - M P Culbert
- University of Leeds, Institute of Medical and Biological Engineering, Leeds, LS2 9JT, United Kingdom
| | - M Mengoni
- University of Leeds, Institute of Medical and Biological Engineering, Leeds, LS2 9JT, United Kingdom
| | - R K Wilcox
- University of Leeds, Institute of Medical and Biological Engineering, Leeds, LS2 9JT, United Kingdom.
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19
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Du Y, Tavana S, Rahman T, Baxan N, Hansen UN, Newell N. Sensitivity of Intervertebral Disc Finite Element Models to Internal Geometric and Non-geometric Parameters. Front Bioeng Biotechnol 2021; 9:660013. [PMID: 34222211 PMCID: PMC8247778 DOI: 10.3389/fbioe.2021.660013] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 05/25/2021] [Indexed: 11/16/2022] Open
Abstract
Finite element models are useful for investigating internal intervertebral disc (IVD) behaviours without using disruptive experimental techniques. Simplified geometries are commonly used to reduce computational time or because internal geometries cannot be acquired from CT scans. This study aimed to (1) investigate the effect of altered geometries both at endplates and the nucleus-anulus boundary on model response, and (2) to investigate model sensitivity to material and geometric inputs, and different modelling approaches (graduated or consistent fibre bundle angles and glued or cohesive inter-lamellar contact). Six models were developed from 9.4 T MRIs of bovine IVDs. Models had two variations of endplate geometry (a simple curved profile from the centre of the disc to the periphery, and precise geometry segmented from MRIs), and three variations of NP-AF boundary (linear, curved, and segmented). Models were subjected to axial compressive loading (to 0.86 mm at a strain rate of 0.1/s) and the effect on stiffness and strain distributions, and the sensitivity to modelling approaches was investigated. The model with the most complex geometry (segmented endplates, curved NP-AF boundary) was 3.1 times stiffer than the model with the simplest geometry (curved endplates, linear NP-AF boundary), although this difference may be exaggerated since segmenting the endplates in the complex geometry models resulted in a shorter average disc height. Peak strains were close to the endplates at locations of high curvature in the segmented endplate models which were not captured in the curved endplate models. Differences were also seen in sensitivity to material properties, graduated fibre angles, cohesive rather than glued inter-lamellar contact, and NP:AF ratios. These results show that FE modellers must take care to ensure geometries are realistic so that load is distributed and passes through IVDs accurately.
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Affiliation(s)
- Yuekang Du
- Biomechanics Group, Department of Mechanical Engineering, Imperial College London, London, United Kingdom
| | - Saman Tavana
- Biomechanics Group, Department of Mechanical Engineering, Imperial College London, London, United Kingdom
| | - Tamanna Rahman
- Biomechanics Group, Department of Mechanical Engineering, Imperial College London, London, United Kingdom
| | - Nicoleta Baxan
- Biological Imaging Centre, Central Biomedical Services, Imperial College London, London, United Kingdom
| | - Ulrich N. Hansen
- Biomechanics Group, Department of Mechanical Engineering, Imperial College London, London, United Kingdom
| | - Nicolas Newell
- Biomechanics Group, Department of Mechanical Engineering, Imperial College London, London, United Kingdom
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20
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McMorran JG, Gregory DE. The effect of compressive loading rate on annulus fibrosus strength following endplate fracture. Med Eng Phys 2021; 93:17-26. [PMID: 34154771 DOI: 10.1016/j.medengphy.2021.05.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 04/14/2021] [Accepted: 05/18/2021] [Indexed: 02/07/2023]
Abstract
Intervertebral disc degeneration poses a considerable healthcare challenge, although the process is not well understood. Endplate fracture marks severe biomechanical compromise in a segment and may be correlated with degeneration of the disc. The purpose of this experiment was to investigate the relationship between endplate fracture velocity and damage to the annulus fibrosus. Following overnight-thawing, 27 frozen porcine cervical spines were dissected into motion segments (vertebra-disc-vertebra) and compressed until fracture at one of three loading rates (fast=15 mm/s, medium=1.5 mm/s, and slow=0.15 mm/s), or remained unfractured (control). Two annular samples were extracted and mechanically tested from each segment: 1) Bilayer samples underwent uniaxial tension to a stretch-ratio of 1.5; 2) Multilayer samples were delaminated with a 180° peel test configuration. All three rates of compression resulted in specimen fracture observed in the endplate and/or vertebra with varying degree of severity. Significant differences were detected in compressive strength and stiffness of motion segments when loaded at different rates of compression; interestingly these differences were not observed in the mechanical properties of the annulus fibrosus suggesting that at slow rates of loading, fracture of the endplate precedes destruction of the annulus fibrosus. In corroboration of these findings, gross and histological analysis reported no signs of annular disruption, strengthening assertions that annular damage did not occur.
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Affiliation(s)
- John G McMorran
- Department of Kinesiology and Physical Education, Wilfrid Laurier University, 75 University Ave West, Waterloo N2L3C5, ON Canada
| | - Diane E Gregory
- Department of Kinesiology and Physical Education, Wilfrid Laurier University, 75 University Ave West, Waterloo N2L3C5, ON Canada; Department of Health Sciences, Wilfrid Laurier University, 75 University Ave West, Waterloo N2L3C5, Ontario, Canada.
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21
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McMorran JG, Gregory DE. The Influence of Axial Compression on the Cellular and Mechanical Function of Spinal Tissues; Emphasis on the Nucleus Pulposus and Annulus Fibrosus: A Review. J Biomech Eng 2021; 143:050802. [PMID: 33454730 DOI: 10.1115/1.4049749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Indexed: 11/08/2022]
Abstract
In light of the correlation between chronic back pain and intervertebral disc (IVD) degeneration, this literature review seeks to illustrate the importance of the hydraulic response across the nucleus pulposus (NP)-annulus fibrosus (AF) interface, by synthesizing current information regarding injurious biomechanics of the spine, stemming from axial compression. Damage to vertebrae, endplates (EPs), the NP, and the AF, can all arise from axial compression, depending on the segment's posture, the manner in which it is loaded, and the physiological state of tissue. Therefore, this movement pattern was selected to illustrate the importance of the bracing effect of a pressurized NP on the AF, and how injuries interrupting support to the AF may contribute to IVD degeneration.
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Affiliation(s)
- John G McMorran
- Department of Kinesiology and Physical Education, Wilfrid Laurier University, 75 University Avenue West, Waterloo, ON N2 L 3C5
| | - Diane E Gregory
- Department of Kinesiology and Physical Education, Wilfrid Laurier University, 75 University Avenue West, Waterloo, ON N2 L 3C5; Department of Health Sciences, Wilfrid Laurier University, 75 University Avenue West, Waterloo, ON N2 L 3C5
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Cyclic Mechanical Stretch Ameliorates the Degeneration of Nucleus Pulposus Cells through Promoting the ITGA2/PI3K/AKT Signaling Pathway. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:6699326. [PMID: 33815660 PMCID: PMC7990548 DOI: 10.1155/2021/6699326] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Revised: 02/16/2021] [Accepted: 02/24/2021] [Indexed: 12/16/2022]
Abstract
Background Intervertebral disc degeneration (IVDD) is one of the major causes of low back pain and motor deficiency. Nucleus pulposus (NP) degeneration plays a key role in the process of IVDD. The mechanical and biological interactions involved in NP degeneration have not been elucidated. The present study is aimed at investigating the effect and mechanism of cyclic mechanical stretch in regulating the function and degeneration of NP cells. Methods NP cells were subjected to cyclic tensile stress (10% deformation) of 0.1 Hz for 8640 cycles. Cell proliferation was conducted through the MTT assay. The cell cycle and apoptosis were detected by flow cytometry. A gene expression profile chip was used to analyze the differentially expressed genes between the tensile stress group and the control group. Enrichment analysis of Gene Ontology (GO) annotation and signaling pathways were analyzed. Western blot and RNA interference were carried out to investigate the role of the ITGA2/PI3K/AKT pathway in the effect of cyclic mechanical stretch on NP cells. Results NP cells exhibited a greater (P < 0.05) growth rate in the tensile stress group compared to the control group. Cyclic mechanical stress significantly promoted the cell cycle transition of NP cells from the S phase to the G2/M phase. A fewer proportion of apoptotic cells were found in the tensile stress group (P < 0.05), indicating that cyclic mechanical stretch inhibits NP cell apoptosis. Microarray analysis revealed 689 significant differentially expressed genes between the two groups (P < 0.05), of which 333 genes were upregulated and another 356 genes were downregulated. Cyclic mechanical stretch altered the expression of 31 genes involved in the ITGA2/PI3K/AKT pathway and remarkably promoted this pathway in NP cells. Downregulation of ITGA2 and AKT further demonstrated that the PI3K/AKT pathway was responsible for the proliferation and COL2A1 expression of NP cells upon cyclic mechanical stretch. Conclusions Cyclic mechanical stretch promoted the proliferation and cell cycle and reversely inhibited the apoptosis of NP cells. Cyclic mechanical stretch promoted COL2A1 expression and ameliorated the degeneration of NP cells via regulation of the ITGA2/PI3K/AKT signaling pathway. Our results may provide a potential target and a possibility of IVDD disease treatment by ameliorating the degenerative changes.
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Lan T, Shiyu-Hu, Shen Z, Yan B, Chen J. New insights into the interplay between miRNAs and autophagy in the aging of intervertebral discs. Ageing Res Rev 2021; 65:101227. [PMID: 33238206 DOI: 10.1016/j.arr.2020.101227] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 10/27/2020] [Accepted: 11/19/2020] [Indexed: 02/06/2023]
Abstract
Intervertebral disc degeneration (IDD) has been widely known as a main contributor to low back pain which has a negative socioeconomic impact worldwide. However, the underlying mechanism remains unclear. MicroRNAs (miRNAs) are a class of small noncoding RNAs that post-transcriptionally regulate gene expression and serve key roles in the ageing process of intervertebral disc. Autophagy is an evolutionarily conserved process that maintains cellular homeostasis through recycling of nutrients and degradation of damaged or aged cytoplasmic organelles. Autophagy has been proposed as a "double-edged sword" and autophagy dysfunction of IVD cells is considered as a crucial reason of IDD. A rapidly growing number of recent studies demonstrate that both miRNAs and autophagy play important roles in the progression of IDD. Furthermore, accumulated research has indicated that miRNAs target autophagy-related genes and influence the onset and development of IDD. Hence, this review focuses mainly on the current findings regarding the correlations between miRNA, autophagy, and IDD and provides new insights into the role of miRNA-autophagy pathway involved in IDD pathophysiology.
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Derrouiche A, Feki F, Zaïri F, Taktak R, Moulart M, Qu Z, Ismail J, Charfi S, Haddar N, Zaïri F. How pre-strain affects the chemo-torsional response of the intervertebral disc. Clin Biomech (Bristol, Avon) 2020; 76:105020. [PMID: 32416404 DOI: 10.1016/j.clinbiomech.2020.105020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 04/22/2020] [Accepted: 04/26/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND The role of the axial pre-strain on the torsional response of the intervertebral disc remains largely undefined. Moreover, the chemo-mechanical interactions in disc tissues are still unclear and corresponding data are rare in the literature. The paper deals with an in-vitro study of the pre-strain effect on the chemical sensitivity of the disc torsional response. METHODS Fifteen non-frozen 'motion segments' (two vertebrae and the intervening soft tissues) were extracted from the cervical spines of mature sheep. The motion segments were loaded in torsion at various saline concentrations and axial pre-strain levels in order to modulate the intradiscal pressure. After preconditioning with successive low-strain compressions at a magnitude of 0.1 mm (10 cycles at 0.05 mm/s), the motion segment was subjected to a cyclic torsion until a twisting level of 2 deg. at 0.05 deg./s while a constant axial pre-strain (in compression or in tension) is maintained, the saline concentration of the surrounding fluid bath being changed from hypo-osmotic condition to hyper-osmotic condition. FINDINGS Analysis of variance shows that the saline concentration influences the torsional response only when the motion segments are pre-compressed (p < .001) with significant differences between hypo-osmotic condition and hyper-osmotic condition. INTERPRETATION The combination of a compressive pre-strain with twisting amplifies the nucleus hydrostatic pressure on the annulus and the annulus collagen fibers tensions. The proteoglycans density increases with the compressive pre-strain and leads to higher chemical imbalances, which would explain the increase in chemical sensitivity of the disc torsional response.
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Affiliation(s)
- Amil Derrouiche
- Lille University, Civil Engineering and geo-Environmental Laboratory (ULR 4515 LGCgE), 59000 Lille, France
| | - Faten Feki
- Sfax University, ENIS, Materials Engineering and Environment Laboratory (LGME), 3038 Sfax, Tunisia
| | - Fahmi Zaïri
- Lille University, Civil Engineering and geo-Environmental Laboratory (ULR 4515 LGCgE), 59000 Lille, France.
| | - Rym Taktak
- Sfax University, ENIS, Materials Engineering and Environment Laboratory (LGME), 3038 Sfax, Tunisia
| | | | - Zhengwei Qu
- Lille University, Civil Engineering and geo-Environmental Laboratory (ULR 4515 LGCgE), 59000 Lille, France
| | - Jewan Ismail
- Lille University, Civil Engineering and geo-Environmental Laboratory (ULR 4515 LGCgE), 59000 Lille, France
| | - Slim Charfi
- Habib Bourguiba Hospital, Pathology department, 3038 Sfax, Tunisia
| | - Nader Haddar
- Sfax University, ENIS, Materials Engineering and Environment Laboratory (LGME), 3038 Sfax, Tunisia
| | - Fahed Zaïri
- Ramsay Générale de Santé, Hôpital privé Le Bois, 59000 Lille, France
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