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Zhou J, Wang J, Li J, Zhu Z, He Z, Li J, Tang T, Chen H, Du Y, Li Z, Gao M, Zhou Z, Xi Y. Repetitive strikes loading organ culture model to investigate the biological and biomechanical responses of the intervertebral disc. JOR Spine 2024; 7:e1314. [PMID: 38249719 PMCID: PMC10797252 DOI: 10.1002/jsp2.1314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 12/14/2023] [Accepted: 12/23/2023] [Indexed: 01/23/2024] Open
Abstract
Background Disc degeneration is associated with repetitive violent injuries. This study aims to explore the impact of repetitive strikes loading on the biology and biomechanics of intervertebral discs (IVDs) using an organ culture model. Methods IVDs from the bovine tail were isolated and cultured in a bioreactor, with exposure to various loading conditions. The control group was subjected to physiological loading, while the model group was exposed to either one strike loading (compression at 38% of IVD height) or repetitive one strike loading (compression at 38% of IVD height). Disc height and dynamic compressive stiffness were measured after overnight swelling and loading. Furthermore, histological morphology, cell viability, and gene expression were analyzed on Day 32. Glycosaminoglycan (GAG) and nitric oxide (NO) release in conditioned medium were also analyzed. Results The repetitive one strike group exhibited early disc degeneration, characterized by decreased dynamic compression stiffness, the presence of annulus fibrosus clefts, and degradation of the extracellular matrix. Additionally, this group demonstrated significantly higher levels of cell death (p < 0.05) and glycosaminoglycan (GAG) release (p < 0.05) compared to the control group. Furthermore, upregulation of MMP1, MMP13, and ADAMTS5 was observed in both nucleus pulposus (NP) and annulus fibrosus (AF) tissues of the repetitive one strike group (p < 0.05). The one strike group exhibited annulus fibrosus clefts but showed no gene expression changes compared to the control group. Conclusions This study shows that repetitive violent injuries lead to the degeneration of a healthy bovine IVDs, thereby providing new insights into early-stage disc degeneration.
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Affiliation(s)
- Jiaxiang Zhou
- Department of Spinal SurgeryThe Affiliated Hospital of Qingdao UniversityQingdaoChina
| | - Jianmin Wang
- Innovation Platform of Regeneration and Repair of Spinal Cord and Nerve Injury, Department of Orthopaedic SurgeryThe Seventh Affiliated Hospital of Sun Yat‐sen UniversityShenzhenChina
| | - Jianfeng Li
- Innovation Platform of Regeneration and Repair of Spinal Cord and Nerve Injury, Department of Orthopaedic SurgeryThe Seventh Affiliated Hospital of Sun Yat‐sen UniversityShenzhenChina
| | - Zhengya Zhu
- Innovation Platform of Regeneration and Repair of Spinal Cord and Nerve Injury, Department of Orthopaedic SurgeryThe Seventh Affiliated Hospital of Sun Yat‐sen UniversityShenzhenChina
| | - Zhongyuan He
- Innovation Platform of Regeneration and Repair of Spinal Cord and Nerve Injury, Department of Orthopaedic SurgeryThe Seventh Affiliated Hospital of Sun Yat‐sen UniversityShenzhenChina
| | - Junhong Li
- Innovation Platform of Regeneration and Repair of Spinal Cord and Nerve Injury, Department of Orthopaedic SurgeryThe Seventh Affiliated Hospital of Sun Yat‐sen UniversityShenzhenChina
| | - Tao Tang
- Innovation Platform of Regeneration and Repair of Spinal Cord and Nerve Injury, Department of Orthopaedic SurgeryThe Seventh Affiliated Hospital of Sun Yat‐sen UniversityShenzhenChina
| | - Hongkun Chen
- Innovation Platform of Regeneration and Repair of Spinal Cord and Nerve Injury, Department of Orthopaedic SurgeryThe Seventh Affiliated Hospital of Sun Yat‐sen UniversityShenzhenChina
| | - Yukun Du
- Department of Spinal SurgeryThe Affiliated Hospital of Qingdao UniversityQingdaoChina
| | - Zhen Li
- AO Research Institute DavosDavosSwitzerland
| | - Manman Gao
- Innovation Platform of Regeneration and Repair of Spinal Cord and Nerve Injury, Department of Orthopaedic SurgeryThe Seventh Affiliated Hospital of Sun Yat‐sen UniversityShenzhenChina
- Guangdong Provincial Key Laboratory of Orthopedics and TraumatologyThe First Affiliated Hospital of Sun Yat‐sen UniversityGuangzhouChina
- Department of Sport Medicine, Inst Translat MedThe First Affiliated Hospital of Shenzhen University, Shenzhen Second People's HospitalShenzhenChina
- Shenzhen Key Laboratory of Anti‐aging and Regenerative Medicine, Department of Medical Cell Biology and Genetics, Health Sciences CenterShenzhen UniversityShenzhenChina
| | - Zhiyu Zhou
- Innovation Platform of Regeneration and Repair of Spinal Cord and Nerve Injury, Department of Orthopaedic SurgeryThe Seventh Affiliated Hospital of Sun Yat‐sen UniversityShenzhenChina
- Guangdong Provincial Key Laboratory of Orthopedics and TraumatologyThe First Affiliated Hospital of Sun Yat‐sen UniversityGuangzhouChina
| | - Yongming Xi
- Department of Spinal SurgeryThe Affiliated Hospital of Qingdao UniversityQingdaoChina
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Cherif H, Li L, Snuggs J, Li X, Sammon C, Li J, Beckman L, Haglund L, Le Maitre CL. Injectable hydrogel induces regeneration of naturally degenerate human intervertebral discs in a loaded organ culture model. Acta Biomater 2024; 176:201-220. [PMID: 38160855 DOI: 10.1016/j.actbio.2023.12.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 11/30/2023] [Accepted: 12/22/2023] [Indexed: 01/03/2024]
Abstract
Low back pain resulting from disc degeneration is a leading cause of disability worldwide. However, to date few therapies target the cause and fail to repair the intervertebral disc (IVD). This study investigates the ability of an injectable hydrogel (NPgel), to inhibit catabolic protein expression and promote matrix expression in human nucleus pulposus (NP) cells within a tissue explant culture model isolated from degenerate discs. Furthermore, the injection capacity of NPgel into naturally degenerate whole human discs, effects on mechanical function, and resistance to extrusion during loading were investigated. Finally, the induction of potential regenerative effects in a physiologically loaded human organ culture system was investigated following injection of NPgel with or without bone marrow progenitor cells. Injection of NPgel into naturally degenerate human IVDs increased disc height and Young's modulus, and was retained during extrusion testing. Injection into cadaveric discs followed by culture under physiological loading increased MRI signal intensity, restored natural biomechanical properties and showed evidence of increased anabolism and decreased catabolism with tissue integration observed. These results provide essential proof of concept data supporting the use of NPgel as an injectable therapy for disc regeneration. STATEMENT OF SIGNIFICANCE: Low back pain resulting from disc degeneration is a leading cause of disability worldwide. However, to date few therapies target the cause and fail to repair the intervertebral disc. This study investigated the potential regenerative properties of an injectable hydrogel system (NPgel) within human tissue samples. To mimic the human in vivo conditions and the unique IVD niche, a dynamically loaded intact human disc culture system was utilised. NPgel improved the biomechanical properties, increased MRI intensity and decreased degree of degeneration. Furthermore, NPgel induced matrix production and decreased catabolic factors by the native cells of the disc. This manuscript provides evidence for the potential use of NPgel as a regenerative biomaterial for intervertebral disc degeneration.
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Affiliation(s)
- Hosni Cherif
- Department of Surgery, McGill University, Montreal, QC H3G 1A4, Canada
| | - Li Li
- Department of Surgery, McGill University, Montreal, QC H3G 1A4, Canada
| | - Joseph Snuggs
- Oncology and Metabolism Department, Medical School, & INSIGNEO Institute, University of Sheffield, Sheffield, UK; Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, UK
| | - Xuan Li
- Department of Mechanical Engineering, McGill University, Montreal, QC H3A 0C3, Canada
| | - Christopher Sammon
- Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield, UK
| | - Jianyu Li
- Department of Surgery, McGill University, Montreal, QC H3G 1A4, Canada; Department of Mechanical Engineering, McGill University, Montreal, QC H3A 0C3, Canada; Department of Biomedical Engineering, McGill University, Montreal, QC H3A 2B4, Canada
| | - Lorne Beckman
- Department of Surgery, McGill University, Montreal, QC H3G 1A4, Canada
| | - Lisbet Haglund
- Department of Surgery, McGill University, Montreal, QC H3G 1A4, Canada; Shriners Hospital for Children, Montreal, QC H4A 0A9, Canada
| | - Christine L Le Maitre
- Oncology and Metabolism Department, Medical School, & INSIGNEO Institute, University of Sheffield, Sheffield, UK; Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, UK.
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Li X, Liu Y, Li L, Huo R, Ghezelbash F, Ma Z, Bao G, Liu S, Yang Z, Weber MH, Li-Jessen NYK, Haglund L, Li J. Tissue-mimetic hybrid bioadhesives for intervertebral disc repair. Mater Horiz 2023; 10:1705-1718. [PMID: 36857679 DOI: 10.1039/d2mh01242a] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Intervertebral disc (IVD) degeneration and herniation often necessitate surgical interventions including a discectomy with or without a nucleotomy, which results in a loss of the normal nucleus pulposus (NP) and a defect in the annulus fibrosus (AF). Due to the limited regenerative capacity of the IVD tissue, the annular tear may remain a persistent defect and result in recurrent herniation post-surgery. Bioadhesives are promising alternatives but show limited adhesion performance, low regenerative capacity, and inability to prevent re-herniation. Here, we report hybrid bioadhesives that combine an injectable glue and a tough sealant to simultaneously repair and regenerate IVD post-nucleotomy. The glue fills the NP cavity while the sealant seals the AF defect. Strong adhesion occurs with the IVD tissues and survives extreme disc loading. Furthermore, the glue can match native NP mechanically, and support the viability and matrix deposition of encapsulated cells, serving as a suitable cell delivery vehicle to promote NP regeneration. Besides, biomechanical tests with bovine IVD motion segments demonstrate the capacity of the hybrid bioadhesives to restore the biomechanics of bovine discs under cyclic loading and to prevent permanent herniation under extreme loading. This work highlights the synergy of bioadhesive and tissue-engineering approaches. Future works are expected to further improve the tissue specificity of bioadhesives and prove their efficacy for tissue repair and regeneration.
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Affiliation(s)
- Xuan Li
- Department of Mechanical Engineering, McGill University, 817 Sherbrooke St W, Montreal, QC H3A 0C3, Canada.
| | - Yin Liu
- Department of Biomedical Engineering, McGill University, 3775 rue University, Montreal, Quebec H3A 2B4, Canada
| | - Li Li
- Department of Surgery, McGill University, 1650 Cedar Avenue, Room C10.148.2, Montreal, QC, H3G 1A4, Canada.
| | - Ran Huo
- Department of Mechanical Engineering, McGill University, 817 Sherbrooke St W, Montreal, QC H3A 0C3, Canada.
| | - Farshid Ghezelbash
- Department of Mechanical Engineering, McGill University, 817 Sherbrooke St W, Montreal, QC H3A 0C3, Canada.
- Department of Mechanical Engineering, Polytechnique Montreal, Montreal, Quebec H3C 3A7, Canada
| | - Zhenwei Ma
- Department of Mechanical Engineering, McGill University, 817 Sherbrooke St W, Montreal, QC H3A 0C3, Canada.
| | - Guangyu Bao
- Department of Mechanical Engineering, McGill University, 817 Sherbrooke St W, Montreal, QC H3A 0C3, Canada.
| | - Shiyu Liu
- Department of Mechanical Engineering, McGill University, 817 Sherbrooke St W, Montreal, QC H3A 0C3, Canada.
| | - Zhen Yang
- Department of Mechanical Engineering, McGill University, 817 Sherbrooke St W, Montreal, QC H3A 0C3, Canada.
| | - Michael H Weber
- Department of Surgery, McGill University, 1650 Cedar Avenue, Room C10.148.2, Montreal, QC, H3G 1A4, Canada.
| | - Nicole Y K Li-Jessen
- Department of Biomedical Engineering, McGill University, 3775 rue University, Montreal, Quebec H3A 2B4, Canada
- School of Communication Sciences and Disorders, McGill University, Montreal, Quebec H3A 1G1, Canada
- Department of Otolaryngology-Head & Neck Surgery, McGill University, Montreal, Quebec H3A 1G1, Canada
| | - Lisbet Haglund
- Department of Surgery, McGill University, 1650 Cedar Avenue, Room C10.148.2, Montreal, QC, H3G 1A4, Canada.
| | - Jianyu Li
- Department of Mechanical Engineering, McGill University, 817 Sherbrooke St W, Montreal, QC H3A 0C3, Canada.
- Department of Biomedical Engineering, McGill University, 3775 rue University, Montreal, Quebec H3A 2B4, Canada
- Department of Surgery, McGill University, 1650 Cedar Avenue, Room C10.148.2, Montreal, QC, H3G 1A4, Canada.
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Salzer E, Mouser VHM, Bulsink JA, Tryfonidou MA, Ito K. Dynamic loading leads to increased metabolic activity and spatial redistribution of viable cell density in nucleus pulposus tissue. JOR Spine 2023; 6:e1240. [PMID: 36994465 PMCID: PMC10041377 DOI: 10.1002/jsp2.1240] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 11/26/2022] [Accepted: 12/13/2022] [Indexed: 01/05/2023] Open
Abstract
Background Nucleus pulposus (NP) cell density is orchestrated by an interplay between nutrient supply and metabolite accumulation. Physiological loading is essential for tissue homeostasis. However, dynamic loading is also believed to increase metabolic activity and could thereby interfere with cell density regulation and regenerative strategies. The aim of this study was to determine whether dynamic loading could reduce the NP cell density by interacting with its energy metabolism. Methods Bovine NP explants were cultured in a novel NP bioreactor with and without dynamic loading in milieus mimicking the pathophysiological or physiological NP environment. The extracellular content was evaluated biochemically and by Alcian Blue staining. Metabolic activity was determined by measuring glucose and lactate in tissue and medium supernatants. A lactate-dehydrogenase staining was performed to determine the viable cell density (VCD) in the peripheral and core regions of the NP. Results The histological appearance and tissue composition of NP explants did not change in any of the groups. Glucose levels in the tissue reached critical values for cell survival (≤0.5 mM) in all groups. Lactate released into the medium was increased in the dynamically loaded compared to the unloaded groups. While the VCD was unchanged on Day 2 in all regions, it was significantly reduced in the dynamically loaded groups on Day 7 (p ≤ 0.01) in the NP core, which led to a gradient formation of VCD in the group with degenerated NP milieu and dynamic loading (p ≤ 0.05). Conclusion It was demonstrated that dynamic loading in a nutrient deprived environment similar to that during IVD degeneration can increase cell metabolism to the extent that it was associated with changes in cell viability leading to a new equilibrium in the NP core. This should be considered for cell injections and therapies that lead to cell proliferation for treatment of IVD degeneration.
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Affiliation(s)
- Elias Salzer
- Orthopaedic Biomechanics, Department of Biomedical EngineeringEindhoven University of TechnologyEindhovenThe Netherlands
| | - Vivian H. M. Mouser
- Orthopaedic Biomechanics, Department of Biomedical EngineeringEindhoven University of TechnologyEindhovenThe Netherlands
| | - Jurgen A. Bulsink
- Orthopaedic Biomechanics, Department of Biomedical EngineeringEindhoven University of TechnologyEindhovenThe Netherlands
| | - Marianna A. Tryfonidou
- Department of Clinical Sciences, Faculty of Veterinary MedicineUtrecht UniversityUtrechtThe Netherlands
| | - Keita Ito
- Orthopaedic Biomechanics, Department of Biomedical EngineeringEindhoven University of TechnologyEindhovenThe Netherlands
- Institute for Complex Molecular SystemsEindhoven University of TechnologyEindhovenThe Netherlands
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Guo W, Douma L, Hu MH, Eglin D, Alini M, Šećerović A, Grad S, Peng X, Zou X, D'Este M, Peroglio M. Hyaluronic acid-based interpenetrating network hydrogel as a cell carrier for nucleus pulposus repair. Carbohydr Polym 2022; 277:118828. [PMID: 34893245 DOI: 10.1016/j.carbpol.2021.118828] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 10/08/2021] [Accepted: 10/27/2021] [Indexed: 01/19/2023]
Abstract
Hyaluronic acid (HA) is a key component of the intervertebral disc (IVD) that is widely investigated as an IVD biomaterial. One persisting challenge is introducing materials capable of supporting cell encapsulation and function, yet with sufficient mechanical stability. In this study, a hybrid interpenetrating polymer network (IPN) was produced as a non-covalent hydrogel, based on a covalently cross-linked HA (HA-BDDE) and HA-poly(N-isopropylacrylamide) (HA-pNIPAM). The hybrid IPN was investigated for its physicochemical properties, with histology and gene expression analysis to determine matrix deposition in vitro and in an ex vivo model. The IPN hydrogel displayed cohesiveness for at least one week and rheological properties resembling native nucleus pulposus (NP) tissue. When implanted in an ex vivo IVD organ culture model, the IPN supported cell viability, phenotype expression of encapsulated NP cells and IVD matrix production over four weeks under physiological loading. Overall, our results indicate the therapeutic potential of this HA-based IPN hydrogel for IVD regeneration.
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Affiliation(s)
- Wei Guo
- AO Research Institute Davos, Clavadelerstrasse 8, 7270 Davos, Switzerland; Department of Spinal Surgery, Orthopaedic Research Institute, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, PR China; Guangdong Provincial Key Laboratory of Orthopaedics and Traumatology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, PR China
| | - Luzia Douma
- AO Research Institute Davos, Clavadelerstrasse 8, 7270 Davos, Switzerland
| | - Ming Hsien Hu
- AO Research Institute Davos, Clavadelerstrasse 8, 7270 Davos, Switzerland
| | - David Eglin
- AO Research Institute Davos, Clavadelerstrasse 8, 7270 Davos, Switzerland
| | - Mauro Alini
- AO Research Institute Davos, Clavadelerstrasse 8, 7270 Davos, Switzerland
| | - Amra Šećerović
- AO Research Institute Davos, Clavadelerstrasse 8, 7270 Davos, Switzerland
| | - Sibylle Grad
- AO Research Institute Davos, Clavadelerstrasse 8, 7270 Davos, Switzerland
| | - Xinsheng Peng
- Department of Spinal Surgery, Orthopaedic Research Institute, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, PR China; Guangdong Provincial Key Laboratory of Orthopaedics and Traumatology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, PR China
| | - Xuenong Zou
- Department of Spinal Surgery, Orthopaedic Research Institute, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, PR China; Guangdong Provincial Key Laboratory of Orthopaedics and Traumatology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, PR China
| | - Matteo D'Este
- AO Research Institute Davos, Clavadelerstrasse 8, 7270 Davos, Switzerland.
| | - Marianna Peroglio
- AO Research Institute Davos, Clavadelerstrasse 8, 7270 Davos, Switzerland
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Mainardi A, Cambria E, Occhetta P, Martin I, Barbero A, Schären S, Mehrkens A, Krupkova O. Intervertebral Disc-on-a-Chip as Advanced In Vitro Model for Mechanobiology Research and Drug Testing: A Review and Perspective. Front Bioeng Biotechnol 2022; 9:826867. [PMID: 35155416 PMCID: PMC8832503 DOI: 10.3389/fbioe.2021.826867] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 12/20/2021] [Indexed: 12/14/2022] Open
Abstract
Discogenic back pain is one of the most diffused musculoskeletal pathologies and a hurdle to a good quality of life for millions of people. Existing therapeutic options are exclusively directed at reducing symptoms, not at targeting the underlying, still poorly understood, degenerative processes. Common intervertebral disc (IVD) disease models still do not fully replicate the course of degenerative IVD disease. Advanced disease models that incorporate mechanical loading are needed to investigate pathological causes and processes, as well as to identify therapeutic targets. Organs-on-chip (OoC) are microfluidic-based devices that aim at recapitulating tissue functions in vitro by introducing key features of the tissue microenvironment (e.g., 3D architecture, soluble signals and mechanical conditioning). In this review we analyze and depict existing OoC platforms used to investigate pathological alterations of IVD cells/tissues and discuss their benefits and limitations. Starting from the consideration that mechanobiology plays a pivotal role in both IVD homeostasis and degeneration, we then focus on OoC settings enabling to recapitulate physiological or aberrant mechanical loading, in conjunction with other relevant features (such as inflammation). Finally, we propose our view on design criteria for IVD-on-a-chip systems, offering a future perspective to model IVD mechanobiology.
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Affiliation(s)
- Andrea Mainardi
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
- Department of Biomedical Engineering, University of Basel, Allschwil, Switzerland
| | - Elena Cambria
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Paola Occhetta
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Ivan Martin
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
- Department of Biomedical Engineering, University of Basel, Allschwil, Switzerland
| | - Andrea Barbero
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
| | - Stefan Schären
- Spine Surgery, University Hospital Basel, Basel, Switzerland
| | - Arne Mehrkens
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
- Spine Surgery, University Hospital Basel, Basel, Switzerland
| | - Olga Krupkova
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
- Spine Surgery, University Hospital Basel, Basel, Switzerland
- Lepage Research Institute, University of Prešov, Prešov, Slovakia
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8
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Wang Y, Kang J, Guo X, Zhu D, Liu M, Yang L, Zhang G, Kang X. Intervertebral Disc Degeneration Models for Pathophysiology and Regenerative Therapy -Benefits and Limitations. J INVEST SURG 2021; 35:935-952. [PMID: 34309468 DOI: 10.1080/08941939.2021.1953640] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Aim:This review summarized the recent intervertebral disc degeneration (IDD) models and described their advantages and potential disadvantages, aiming to provide an overview for the current condition of IDD model establishment and new ideas for new strategies development of the treatment and prevention of IDD.Methods:The database of PubMed was searched up to May 2021 with the following search terms: nucleus pulposus, annulus fibrosus, cartilage endplate, intervertebral disc(IVD), intervertebral disc degeneration, animal model, organ culture, bioreactor, inflammatory reaction, mechanical stress, pathophysiology, epidemiology. Any IDD model-related articles were collected and summarized.Results:The best IDD model should have the features of repeatability, measurability and controllability. There are a lot of aspects to be considered in the selection of animals. Mice, rats and rabbits are low-cost and easy to access. However, their IVD size and shape are more different from human anatomy than pigs, cattle, sheep and goats. Organ culture models and animal models are two options in model establishment for IDD. The IVD organ culture model can put the studying variables into the controllable system for transitional research. Unlike the animal model, the organ culture model can only be used to evaluate the short-term effects and it is not applicable in simulating the complex process of IDD. Similarly, the animal models induced by different methods also have their advantages and disadvantages. For studying the mechanism of IDD and the corresponding treatment and prevention strategies, the selection of model should be individualized based on the purpose of each study.Conclusions:Various models have different characteristics and scope of application due to their different rationales and methods of construction. Currently, there is no experimental model that can perfectly mimic the degenerative process of human IVD. Personalized selection of appropriate model based on study purpose and experimental designing can enhance the possibility to obtain reliable and real results.
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Affiliation(s)
- Yidian Wang
- The Second Clinical Medical College, Lanzhou University, Lanzhou, P.R. China
| | - Jihe Kang
- The Second Clinical Medical College, Lanzhou University, Lanzhou, P.R. China
| | - Xudong Guo
- The Second Clinical Medical College, Lanzhou University, Lanzhou, P.R. China
| | - Daxue Zhu
- The Second Clinical Medical College, Lanzhou University, Lanzhou, P.R. China
| | - Mingqiang Liu
- The Second Clinical Medical College, Lanzhou University, Lanzhou, P.R. China
| | - Liang Yang
- The Second Clinical Medical College, Lanzhou University, Lanzhou, P.R. China
| | - Guangzhi Zhang
- The Second Clinical Medical College, Lanzhou University, Lanzhou, P.R. China
| | - Xuewen Kang
- The Second Clinical Medical College, Lanzhou University, Lanzhou, P.R. China.,Department of Orthopedics, Lanzhou University Second Hospital, Lanzhou, P.R. China.,The International Cooperation Base of Gansu Province for The Pain Research in Spinal Disorders, Gansu, P.R. China
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Hughes DL, Hughes A, Soonawalla Z, Mukherjee S, O’Neill E. Dynamic Physiological Culture of Ex Vivo Human Tissue: A Systematic Review. Cancers (Basel) 2021; 13:2870. [PMID: 34201273 PMCID: PMC8229413 DOI: 10.3390/cancers13122870] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/26/2021] [Accepted: 06/03/2021] [Indexed: 12/20/2022] Open
Abstract
Conventional static culture fails to replicate the physiological conditions that exist in vivo. Recent advances in biomedical engineering have resulted in the creation of novel dynamic culturing systems that permit the recapitulation of normal physiological processes ex vivo. Whilst the physiological benefit for its use in the culture of two-dimensional cellular monolayer has been validated, its role in the context of primary human tissue culture has yet to be determined. This systematic review identified 22 articles that combined dynamic physiological culture techniques with primary human tissue culture. The most frequent method described (55%) utilised dynamic perfusion culture. A diverse range of primary human tissue was successfully cultured. The median duration of successful ex vivo culture of primary human tissue for all articles was eight days; however, a wide range was noted (5 h-60 days). Six articles (27%) reported successful culture of primary human tissue for greater than 20 days. This review illustrates the physiological benefit of combining dynamic culture with primary human tissue culture in both long-term culture success rates and preservation of native functionality of the tissue ex vivo. Further research efforts should focus on developing precise biochemical sensors that would allow for real-time monitoring and automated self-regulation of the culture system in order to maintain homeostasis. Combining these techniques allows the creation of an accurate system that can be used to gain a greater understanding of human physiology.
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Affiliation(s)
- Daniel Ll Hughes
- Department of Oncology, University of Oxford, Oxford OX3 7DQ, UK; (D.L.H.); (S.M.)
| | - Aron Hughes
- Undergraduate Centre, Cardiff University Medical School, Cardiff CF14 4YS, UK;
| | - Zahir Soonawalla
- Department of Hepatobiliary and Pancreatic Surgery, Oxford University Hospitals NHS, Oxford OX3 7LE, UK;
| | - Somnath Mukherjee
- Department of Oncology, University of Oxford, Oxford OX3 7DQ, UK; (D.L.H.); (S.M.)
| | - Eric O’Neill
- Department of Oncology, University of Oxford, Oxford OX3 7DQ, UK; (D.L.H.); (S.M.)
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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11
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Mannarino M, Cherif H, Li L, Sheng K, Rabau O, Jarzem P, Weber MH, Ouellet JA, Haglund L. Toll-like receptor 2 induced senescence in intervertebral disc cells of patients with back pain can be attenuated by o-vanillin. Arthritis Res Ther 2021; 23:117. [PMID: 33863359 PMCID: PMC8051055 DOI: 10.1186/s13075-021-02504-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 04/03/2021] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND There is an increased level of senescent cells and toll-like teceptor-1, -2, -4, and -6 (TLR) expression in degenerating intervertebral discs (IVDs) from back pain patients. However, it is currently not known if the increase in expression of TLRs is related to the senescent cells or if it is a more general increase on all cells. It is also not known if TLR activation in IVD cells will induce cell senescence. METHODS Cells from non-degenerate human IVD were obtained from spine donors and cells from degenerate IVDs came from patients undergoing surgery for low back pain. Gene expression of TLR-1,2,4,6, senescence and senescence-associated secretory phenotype (SASP) markers was evaluated by RT-qPCR in isolated cells. Matrix synthesis was verified with safranin-O staining and Dimethyl-Methylene Blue Assay (DMMB) confirmed proteoglycan content. Protein expression of p16INK4a, SASP factors, and TLR-2 was evaluated by immunocytochemistry (ICC) and/or by enzyme-linked immunosorbent assay (ELISA). RESULTS An increase in senescent cells was found following 48-h induction with a TLR-2/6 agonist in cells from both non-degenerate and degenerating human IVDs. Higher levels of SASP factors, TLR-2 gene expression, and protein expression were found following 48-h induction with TLR-2/6 agonist. Treatment with o-vanillin reduced the number of senescent cells, and increased matrix synthesis in IVD cells from back pain patients. Treatment with o-vanillin after induction with TLR-2/6 agonist reduced gene and protein expression of SASP factors and TLR-2. Co-localized staining of p16INK4a and TLR-2 demonstrated that senescent cells have a high TLR-2 expression. CONCLUSIONS Taken together our data demonstrate that activation of TLR-2/6 induce senescence and increase TLR-2 and SASP expression in cells from non-degenerate IVDs of organ donors without degeneration and back pain and in cells from degenerating human IVD of patients with disc degeneration and back pain. The senescent cells showed high TLR-2 expression suggesting a link between TLR activation and cell senescence in human IVD cells. The reduction in senescence, SASP, and TLR-2 expression suggest o-vanillin as a potential disease-modifying drug for patients with disc degeneration and back pain.
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Affiliation(s)
- Matthew Mannarino
- Department of Surgery, Orthopaedic Research Lab, McGill University, Montreal, Canada
- Department of Surgery, McGill Scoliosis and Spine Group, McGill University, Montreal, Canada
- Department of Surgery, The Research Institute of McGill University Health Center, Montreal, Canada
| | - Hosni Cherif
- Department of Surgery, Orthopaedic Research Lab, McGill University, Montreal, Canada
- Department of Surgery, McGill Scoliosis and Spine Group, McGill University, Montreal, Canada
- Department of Surgery, The Research Institute of McGill University Health Center, Montreal, Canada
| | - Li Li
- Department of Surgery, Orthopaedic Research Lab, McGill University, Montreal, Canada
- Department of Surgery, McGill Scoliosis and Spine Group, McGill University, Montreal, Canada
- Department of Surgery, The Research Institute of McGill University Health Center, Montreal, Canada
| | - Kai Sheng
- Department of Surgery, Orthopaedic Research Lab, McGill University, Montreal, Canada
- Department of Surgery, McGill Scoliosis and Spine Group, McGill University, Montreal, Canada
- Shriner's Hospital for Children, Montreal, Canada
| | - Oded Rabau
- Department of Surgery, McGill Scoliosis and Spine Group, McGill University, Montreal, Canada
- Shriner's Hospital for Children, Montreal, Canada
| | - Peter Jarzem
- Department of Surgery, Orthopaedic Research Lab, McGill University, Montreal, Canada
- Department of Surgery, McGill Scoliosis and Spine Group, McGill University, Montreal, Canada
- Department of Surgery, The Research Institute of McGill University Health Center, Montreal, Canada
| | - Michael H Weber
- Department of Surgery, Orthopaedic Research Lab, McGill University, Montreal, Canada
- Department of Surgery, McGill Scoliosis and Spine Group, McGill University, Montreal, Canada
- Department of Surgery, The Research Institute of McGill University Health Center, Montreal, Canada
| | - Jean A Ouellet
- Department of Surgery, Orthopaedic Research Lab, McGill University, Montreal, Canada
- Department of Surgery, McGill Scoliosis and Spine Group, McGill University, Montreal, Canada
- Department of Surgery, The Research Institute of McGill University Health Center, Montreal, Canada
- Shriner's Hospital for Children, Montreal, Canada
| | - Lisbet Haglund
- Department of Surgery, Orthopaedic Research Lab, McGill University, Montreal, Canada.
- Department of Surgery, McGill Scoliosis and Spine Group, McGill University, Montreal, Canada.
- Department of Surgery, The Research Institute of McGill University Health Center, Montreal, Canada.
- Shriner's Hospital for Children, Montreal, Canada.
- Department of Surgery, Montreal General Hospital, McGill University Health Centre, Room C9.173,1650 Cedar Ave, Montreal, QC, H3G 1A4, Canada.
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12
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Duclos SE, Denning SK, Towler C, Michalek AJ. Level-wise differences in in vivo lateral bending moment are associated with microstructural alterations in bovine caudal intervertebral discs. J Exp Biol 2020; 223:jeb229971. [PMID: 32958522 DOI: 10.1242/jeb.229971] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 09/07/2020] [Indexed: 11/20/2022]
Abstract
Despite its common use as a laboratory model, little is known about the in vivo forces and moments applied to the bovine caudal intervertebral disc. Such aspects are crucial, as intervertebral disc tissue is known to remodel in response to repeated loading. We hypothesized that the magnitude of loading from muscle contraction during a typical lateral bending motion varies between caudal levels and is accompanied by variations in tissue microstructure. This hypothesis was tested by estimating level-wise forces and bending moments using two independent approaches: a dynamic analytical model of the motion and analysis of muscle cross-sections obtained via computed tomography. Microstructure was assessed by measuring the collagen fiber crimp period in the annulus fibrosus, and composition was assessed via quantitative histology. Both the analytical model and muscle cross-sections indicated peak bending moments of over 3 N m and peak compressive force of over 125 N at the c1c2 level, decreasing distally. There was a significant downward trend from proximal to distal in the outer annulus fibrosus collagen crimp period in the anterior and posterior regions only, suggesting remodeling in response to the highest lateral bending moments. There were no observed trends in composition. Our results suggest that although the proximal discs in the bovine tail are subjected to forces and moments from muscle contraction that are comparable (relative to disc size) to those acting on human lumbar discs, the distal discs are not. The resulting pattern of microstructural alterations suggests that level-wise differences should be considered when using bovine discs as a research model.
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Affiliation(s)
- Sarah E Duclos
- Department of Mechanical & Aeronautical Engineering, Clarkson University, Potsdam, NY 13699, USA
| | - Samantha K Denning
- Department of Mechanical & Aeronautical Engineering, Clarkson University, Potsdam, NY 13699, USA
| | - Christopher Towler
- Department of Physical Therapy, Clarkson University, Potsdam, NY 13699, USA
| | - Arthur J Michalek
- Department of Mechanical & Aeronautical Engineering, Clarkson University, Potsdam, NY 13699, USA
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Harmon MD, Ramos DM, Nithyadevi D, Bordett R, Rudraiah S, Nukavarapu SP, Moss IL, Kumbar SG. Growing a backbone - functional biomaterials and structures for intervertebral disc (IVD) repair and regeneration: challenges, innovations, and future directions. Biomater Sci 2020; 8:1216-1239. [PMID: 31957773 DOI: 10.1039/c9bm01288e] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Back pain and associated maladies can account for an immense amount of healthcare cost and loss of productivity in the workplace. In particular, spine related injuries in the US affect upwards of 5.7 million people each year. The degenerative disc disease treatment almost always arises due to a clinical presentation of pain and/or discomfort. Preferred conservative treatment modalities include the use of non-steroidal anti-inflammatory medications, physical therapy, massage, acupuncture, chiropractic work, and dietary supplements like glucosamine and chondroitin. Artificial disc replacement, also known as total disc replacement, is a treatment alternative to spinal fusion. The goal of artificial disc prostheses is to replicate the normal biomechanics of the spine segment, thereby preventing further damage to neighboring sections. Artificial functional disc replacement through permanent metal and polymer-based components continues to evolve, but is far from recapitulating native disc structure and function, and suffers from the risk of unsuccessful tissue integration and device failure. Tissue engineering and regenerative medicine strategies combine novel material structures, bioactive factors and stem cells alone or in combination to repair and regenerate the IVD. These efforts are at very early stages and a more in-depth understanding of IVD metabolism and cellular environment will also lead to a clearer understanding of the native environment which the tissue engineering scaffold should mimic. The current review focusses on the strategies for a successful regenerative scaffold for IVD regeneration and the need for defining new materials, environments, and factors that are so finely tuned in the healthy human intervertebral disc in hopes of treating such a prevalent degenerative process.
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Affiliation(s)
- Matthew D Harmon
- Department of Materials Science and Engineering, University of Connecticut, Storrs, CT, USA. and Department of Orthopedics Surgery, University of Connecticut Health, Farmington, CT, USA
| | - Daisy M Ramos
- Department of Materials Science and Engineering, University of Connecticut, Storrs, CT, USA. and Department of Orthopedics Surgery, University of Connecticut Health, Farmington, CT, USA
| | - D Nithyadevi
- Department of Orthopedics Surgery, University of Connecticut Health, Farmington, CT, USA
| | - Rosalie Bordett
- Department of Orthopedics Surgery, University of Connecticut Health, Farmington, CT, USA
| | - Swetha Rudraiah
- Department of Pharmaceutical Sciences, University of Saint Joseph, Hartford, CT, USA
| | - Syam P Nukavarapu
- Department of Materials Science and Engineering, University of Connecticut, Storrs, CT, USA. and Department of Orthopedics Surgery, University of Connecticut Health, Farmington, CT, USA and Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA
| | - Isaac L Moss
- Department of Orthopedics Surgery, University of Connecticut Health, Farmington, CT, USA
| | - Sangamesh G Kumbar
- Department of Materials Science and Engineering, University of Connecticut, Storrs, CT, USA. and Department of Orthopedics Surgery, University of Connecticut Health, Farmington, CT, USA and Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA
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14
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Takeoka Y, Kang JD, Mizuno S. In vitro nucleus pulposus tissue model with physicochemical stresses. JOR Spine 2020; 3:e1105. [PMID: 33015578 PMCID: PMC7524234 DOI: 10.1002/jsp2.1105] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 05/12/2020] [Accepted: 06/04/2020] [Indexed: 12/21/2022] Open
Abstract
Intervertebral discs (IVDs) are exposed to changes in physicochemical stresses including hydrostatic and osmotic pressure via diurnal spinal motion. Homeostasis, degeneration, and regeneration in IVDs have been studied using in vitro, ex vivo, and animal models. However, incubation of nucleus pulposus (NP) cells in medium has limited capability to reproduce anabolic turnover and regeneration under physicochemical stresses. We developed a novel pressure/perfusion cell culture system and a semipermeable membrane pouch device for enclosing isolated NP cells for in vitro incubation under physicochemical stresses. We assessed the performance of this system to identify an appropriate stress loading regimen to promote gene expression and consistent accumulation of extracellular matrices by bovine caudal NP cells. Cyclic hydrostatic pressure (HP) for 4 days followed by constant HP for 3 days in high osmolality (HO; 450 mOsm/kg H2O) showed a trend towards upregulated aggrecan expression and dense accumulation of keratan sulfate without gaps by the NP cells. Furthermore, a repetitive regimen of cyclic HP for 2 days followed by constant HP for 1 day in HO (repeated twice) significantly upregulated gene expression of aggrecan (P < .05) compared to no pressure and suppressed matrix metalloproteinase-13 expression (P < .05) at 6 days. Our culture system and pouches will be useful to reproduce physicochemical stresses in NP cells for simulating anabolic, catabolic, and homeostatic turnover under diurnal spinal motion.
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Affiliation(s)
- Yoshiki Takeoka
- Department of Orthopaedic SurgeryBrigham and Women's Hospital and Harvard Medical SchoolBostonMassachusettsUSA
| | - James D. Kang
- Department of Orthopaedic SurgeryBrigham and Women's Hospital and Harvard Medical SchoolBostonMassachusettsUSA
| | - Shuichi Mizuno
- Department of Orthopaedic SurgeryBrigham and Women's Hospital and Harvard Medical SchoolBostonMassachusettsUSA
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15
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Cherif H, Bisson DG, Mannarino M, Rabau O, Ouellet JA, Haglund L. Senotherapeutic drugs for human intervertebral disc degeneration and low back pain. eLife 2020; 9:54693. [PMID: 32821059 PMCID: PMC7442487 DOI: 10.7554/elife.54693] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Accepted: 08/03/2020] [Indexed: 12/12/2022] Open
Abstract
Cellular senescence is a contributor to intervertebral disc (IVD) degeneration and low back pain. Here, we found that RG-7112, a potent mouse double-minute two protein inhibitor, selectively kills senescent IVD cells through apoptosis. Gene expression pathway analysis was used to compare the functional networks of genes affected by RG-7112, a pure synthetic senolytic with o-Vanillin a natural and anti-inflammatory senolytic. Both affected a functional gene network related to cell death and survival. O-Vanillin also affected networks related to cell cycle progression as well as connective tissue development and function. Both senolytics effectively decreased the senescence-associated secretory phenotype (SASP) of IVD cells. Furthermore, bioavailability and efficacy were verified ex vivo in the physiological environment of degenerating intact human discs where a single dose improved disc matrix homeostasis. Matrix improvement correlated with a reduction in senescent cells and SASP, supporting a translational potential of targeting senescent cells as a therapeutic intervention. Pain in the lower back affects about four in five people during their lifetime. Over time, the discs that provide cushioning between the vertebrae of the spine can degenerate, which can be one of the major causes of lower back pain. It has been shown that when the cells of these discs are exposed to different stress factors, they stop growing and become irreversibly dormant. Such ‘senescent’ cells release a range of proteins and small molecules that lead to painful inflammation and further degeneration of the discs. Moreover, it is thought that a high number of senescent cells may be linked to other degenerative diseases such as arthritis. Current treatments can only reduce the severity of the symptoms, but they cannot prevent the degeneration from progressing. Now, Cherif et al. set out to test the effects of two different compounds on human disc cells grown in the laboratory. One of the molecules studied, RG-7112, is a synthetic drug that has been approved for safety by the US Food and Drug Administration and has been shown to remove senescent cells. The other, o-Vanillin, is a natural compound that has anti-inflammatory and anti-senescence properties. The results showed that both compounds were able to trigger changes to that helped new, healthy cells to grow and at the same time kill senescent cells. They also reduced the production of molecules linked to inflammation and pain. Further analyses revealed that the compounds were able to strengthen the fibrous matrix that surrounds and supports the discs. Cherif et al. hope that this could form the basis for a new family of drugs for back pain to slow the degeneration of the discs and reduce pain. This may also have benefits for other similar degenerative diseases caused by cell senescence, such as arthritis.
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Affiliation(s)
- Hosni Cherif
- Orthopaedic Research Lab, Department of Surgery, McGill University and the Research Institute of the McGill University Health Centre, Montreal, Canada.,McGill Scoliosis and Spine Group, Department of Surgery, McGill University and the Research Institute of the McGill University Health Centre, Montreal, Canada
| | - Daniel G Bisson
- Orthopaedic Research Lab, Department of Surgery, McGill University and the Research Institute of the McGill University Health Centre, Montreal, Canada.,McGill Scoliosis and Spine Group, Department of Surgery, McGill University and the Research Institute of the McGill University Health Centre, Montreal, Canada
| | - Matthew Mannarino
- Orthopaedic Research Lab, Department of Surgery, McGill University and the Research Institute of the McGill University Health Centre, Montreal, Canada.,McGill Scoliosis and Spine Group, Department of Surgery, McGill University and the Research Institute of the McGill University Health Centre, Montreal, Canada
| | - Oded Rabau
- McGill Scoliosis and Spine Group, Department of Surgery, McGill University and the Research Institute of the McGill University Health Centre, Montreal, Canada.,Shriner's Hospital for Children, 1003 Decarie Blvd, Montreal, Canada
| | - Jean A Ouellet
- McGill Scoliosis and Spine Group, Department of Surgery, McGill University and the Research Institute of the McGill University Health Centre, Montreal, Canada.,Shriner's Hospital for Children, 1003 Decarie Blvd, Montreal, Canada
| | - Lisbet Haglund
- Orthopaedic Research Lab, Department of Surgery, McGill University and the Research Institute of the McGill University Health Centre, Montreal, Canada.,McGill Scoliosis and Spine Group, Department of Surgery, McGill University and the Research Institute of the McGill University Health Centre, Montreal, Canada.,Shriner's Hospital for Children, 1003 Decarie Blvd, Montreal, Canada
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16
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Xing Y, Zhang P, Zhang Y, Holzer L, Xiao L, He Y, Majumdar R, Huo J, Yu X, Ramasubramanian MK, Jin L, Wang Y, Li X, Oberholzer J. A multi-throughput mechanical loading system for mouse intervertebral disc. J Mech Behav Biomed Mater 2020; 105:103636. [PMID: 32279855 DOI: 10.1016/j.jmbbm.2020.103636] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 01/07/2020] [Accepted: 01/09/2020] [Indexed: 12/01/2022]
Abstract
Mechanical loading plays an important role in maintaining disc health and function, and in particular, excessive mechanical loading has been identified as one of major reasons of disc degeneration. Intervertebral disc organ culture serves as a valuable tool to study disc biology/pathology. In this study, we report the development and validation of a new mouse disc organ culture system by dynamically applying compression loading in a customized micro-culture device tailored for mouse lumbar discs. Precise axial compression force was delivered by a computer-controlled system consisting of a robust micromechanical linear actuator, a force sensitive resistor, and a precision micro-stepping machinery. Customized PDMS-based loading chambers allowed simultaneous loading of six discs per regimen, which streamlined the workflow to reach sufficient statistic power. The detrimental loading regimen of mouse lumbar discs (0.5 MPa of axial compression at 1Hz for 7 days) was demonstrated through live-dead assay, histology, and fluorescence probe based collagen staining. In addition, various mechanical compression profiles were simulated using different materials and geometry designs, potentiating for more sophisticated loading protocols. In summary, we developed a new mechanical loading system for dynamic axial compression of mouse discs, which created a unique avenue to study disc pathogenesis with enriched mouse species-related resources, and complemented the existing spectrum of bioreactor systems predominately for discs of human and large animals.
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Affiliation(s)
- Yuan Xing
- Department of Surgery, University of Virginia, 345 Crispell Drive, Charlottesville, VA, 22908, United States
| | - Pu Zhang
- Department of Mechanical and Aerospace Engineering, University of Virginia, 122 Engineer's Way, Charlottesville, VA, 22904, United States
| | - Yangpu Zhang
- Department of Orthopaedic Surgery, University of Virginia, 135 Hospital Drive, Charlottesville, VA, 22908, United States; Current Address: Department of Orthopedic Surgery, Beijing Chaoyang Hospital, Capital Medical University, Chaoyang District, Beijing, China
| | - Liam Holzer
- Department of Biomedical Engineering, Purdue University, 206 S Martin Jischke Dr, West Lafayette, IN, 47907, United States
| | - Li Xiao
- Department of Orthopaedic Surgery, University of Virginia, 135 Hospital Drive, Charlottesville, VA, 22908, United States
| | - Yi He
- Department of Surgery, University of Virginia, 345 Crispell Drive, Charlottesville, VA, 22908, United States
| | - Rahul Majumdar
- Department of Orthopaedic Surgery, University of Virginia, 135 Hospital Drive, Charlottesville, VA, 22908, United States
| | - Jianzhong Huo
- Department of Orthopaedic Surgery, University of Virginia, 135 Hospital Drive, Charlottesville, VA, 22908, United States; Current Address: Department of Orthopaedic Surgery, Shanxi DaYi Hospital, 99 Long Road, Taiyuan, Shanxi, 030032, China
| | - Xiaoyu Yu
- Department of Surgery, University of Virginia, 345 Crispell Drive, Charlottesville, VA, 22908, United States
| | - Melur K Ramasubramanian
- Department of Mechanical and Aerospace Engineering, University of Virginia, 122 Engineer's Way, Charlottesville, VA, 22904, United States
| | - Li Jin
- Department of Orthopaedic Surgery, University of Virginia, 135 Hospital Drive, Charlottesville, VA, 22908, United States
| | - Yong Wang
- Department of Surgery, University of Virginia, 345 Crispell Drive, Charlottesville, VA, 22908, United States
| | - Xudong Li
- Department of Orthopaedic Surgery, University of Virginia, 135 Hospital Drive, Charlottesville, VA, 22908, United States.
| | - Jose Oberholzer
- Department of Surgery, University of Virginia, 345 Crispell Drive, Charlottesville, VA, 22908, United States.
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17
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Wangler S, Peroglio M, Menzel U, Benneker LM, Haglund L, Sakai D, Alini M, Grad S. Mesenchymal Stem Cell Homing Into Intervertebral Discs Enhances the Tie2-positive Progenitor Cell Population, Prevents Cell Death, and Induces a Proliferative Response. Spine (Phila Pa 1976) 2019; 44:1613-22. [PMID: 31730570 DOI: 10.1097/BRS.0000000000003150] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Experimental study with human mesenchymal stem cells (MSCs) and intervertebral disc (IVD) tissue samples. OBJECTIVE This study aimed to characterize the effect of MSC homing on the Tie2-positive IVD progenitor cell population, IVD cell survival, and proliferation. SUMMARY OF BACKGROUND DATA Homing of human MSCs has been described as potential alternative to MSC injection, aiming to enhance the regenerative capacity of the IVD. IVD cells expressing Tie2 (also known as CD202b or Angiopoietin-1 receptor TEK tyrosine kinase) represent a progenitor cell population with discogenic differentiation potential. However, the fraction of Tie2-positive progenitor cells decreases with aging and degree of IVD degeneration, resulting in a potential loss of the IVD's regenerative capacity. METHODS Human MSCs, isolated from vertebral bone marrow aspirates, were labeled and seeded onto the endplate of bovine IVDs and human IVD tissue. Following MSC migration for 5 days, IVD cells were isolated by tissue digestion. The fractions of Tie2-positive, dead, apoptotic, and proliferative IVD cells were evaluated by flow cytometry and compared to untreated IVDs. For human IVDs, 3 groups were investigated: nondegenerated (organ donors), IVDs of patients suffering from spinal trauma, and degenerative IVD tissue samples. RESULTS MSC homing enhanced the fraction of Tie2-positive IVD cells in bovine and human IVD samples. Furthermore, a proliferative response and lower fraction of dead cells were observed after MSC homing in both bovine and human IVD tissues. CONCLUSION Our findings indicate that MSC homing enhances the survival and regenerative capability of IVD cells, which may be mediated by intercellular communication. MSC homing could represent a potential treatment strategy to prevent the onset of the degenerative cascade in IVDs at risk such as IVDs adjacent to a fused segment or IVDs after herniation. LEVEL OF EVIDENCE N/A.
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Pfannkuche JJ, Guo W, Cui S, Ma J, Lang G, Peroglio M, Richards RG, Alini M, Grad S, Li Z. Intervertebral disc organ culture for the investigation of disc pathology and regeneration - benefits, limitations, and future directions of bioreactors. Connect Tissue Res 2019; 61:304-321. [PMID: 31556329 DOI: 10.1080/03008207.2019.1665652] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Low back pain is the leading cause of disability worldwide and in many patients the source of pain can be attributed to pathological changes within the intervertebral disc (IVD). As present treatment options fail to address the underlying biological problem, novel therapies are currently subject to intense research. The physiologic IVD microenvironment features a highly complex interaction of biochemical and mechanical factors influencing cell metabolism and extracellular matrix turnover and is therefore difficult to simulate for research purposes on IVD pathology. The first whole organ culture models were not able to sufficiently replicate human in vivo conditions as mechanical loading, the predominant way of IVD nutrient supply and waste exchange, remained disregarded. To mimic the unique IVD niche more realistically, whole organ culture bioreactors have been developed, allowing for dynamic loading of IVDs and nutrient exchange. Recent advancements on bioreactor systems have facilitated whole organ culture of various IVDs for extended periods. IVD organ culture bioreactors have the potential to bridge the gap between in vitro and in vivo systems and thus may give valuable insights on IVD pathology and/or potential novel treatment approaches if the respective model is adjusted according to a well-defined research question. In this review, we outline the potential of currently utilized IVD bioreactor systems and present suggestions for further developments to more reliably investigate IVD biology and novel treatment approaches.
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Affiliation(s)
- Judith-Johanna Pfannkuche
- AO Research Institute Davos, Davos, Switzerland.,Department of Orthopedic and Trauma Surgery, University Medical Center Freiburg, Albert-Ludwigs University of Freiburg, Freiburg, Germany
| | - Wei Guo
- AO Research Institute Davos, Davos, Switzerland.,The first affiliated hospital of Sun Yat-sen University, Guangzhou, China
| | - Shangbin Cui
- AO Research Institute Davos, Davos, Switzerland.,The first affiliated hospital of Sun Yat-sen University, Guangzhou, China
| | - Junxuan Ma
- AO Research Institute Davos, Davos, Switzerland
| | - Gernot Lang
- Department of Orthopedic and Trauma Surgery, University Medical Center Freiburg, Albert-Ludwigs University of Freiburg, Freiburg, Germany
| | | | - R Geoff Richards
- AO Research Institute Davos, Davos, Switzerland.,Department of Orthopedic and Trauma Surgery, University Medical Center Freiburg, Albert-Ludwigs University of Freiburg, Freiburg, Germany
| | - Mauro Alini
- AO Research Institute Davos, Davos, Switzerland
| | | | - Zhen Li
- AO Research Institute Davos, Davos, Switzerland
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Smith LJ, Silverman L, Sakai D, Le Maitre CL, Mauck RL, Malhotra NR, Lotz JC, Buckley CT. Advancing cell therapies for intervertebral disc regeneration from the lab to the clinic: Recommendations of the ORS spine section. JOR Spine 2018; 1:e1036. [PMID: 30895277 PMCID: PMC6419951 DOI: 10.1002/jsp2.1036] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 09/09/2018] [Accepted: 09/10/2018] [Indexed: 12/28/2022] Open
Abstract
Intervertebral disc degeneration is strongly associated with chronic low back pain, a leading cause of disability worldwide. Current back pain treatment approaches (both surgical and conservative) are limited to addressing symptoms, not necessarily the root cause. Not surprisingly therefore, long-term efficacy of most approaches is poor. Cell-based disc regeneration strategies have shown promise in preclinical studies, and represent a relatively low-risk, low-cost, and durable therapeutic approach suitable for a potentially large patient population, thus making them attractive from both clinical and commercial standpoints. Despite such promise, no such therapies have been broadly adopted clinically. In this perspective we highlight primary obstacles and provide recommendations to help accelerate successful clinical translation of cell-based disc regeneration therapies. The key areas addressed include: (a) Optimizing cell sources and delivery techniques; (b) Minimizing potential risks to patients; (c) Selecting physiologically and clinically relevant efficacy metrics; (d) Maximizing commercial potential; and (e) Recognizing the importance of multidisciplinary collaborations and engaging with clinicians from inception through to clinical trials.
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Affiliation(s)
- Lachlan J. Smith
- Department of NeurosurgeryUniversity of PennsylvaniaPhiladelphiaPennsylvania
- Department of Orthopaedic SurgeryUniversity of PennsylvaniaPhiladelphiaPennsylvania
- Translational Musculoskeletal Research CenterCorporal Michael J. Crescenz VA Medical CenterPhiladelphiaPennsylvania
| | - Lara Silverman
- DiscGenics Inc.Salt Lake CityUtah
- Department of NeurosurgeryUniversity of Tennessee Health Science CenterMemphisTennessee
| | - Daisuke Sakai
- Department of Orthopaedic Surgery, Surgical ScienceTokai University School of MedicineIseharaJapan
| | | | - Robert L. Mauck
- Department of Orthopaedic SurgeryUniversity of PennsylvaniaPhiladelphiaPennsylvania
- Translational Musculoskeletal Research CenterCorporal Michael J. Crescenz VA Medical CenterPhiladelphiaPennsylvania
- Department of BioengineeringUniversity of PennsylvaniaPhiladelphiaPennsylvania
| | - Neil R. Malhotra
- Department of NeurosurgeryUniversity of PennsylvaniaPhiladelphiaPennsylvania
| | - Jeffrey C. Lotz
- Department of Orthopaedic SurgeryUniversity of CaliforniaSan FranciscoCalifornia
| | - Conor T. Buckley
- Trinity Centre for BioengineeringTrinity Biomedical Sciences Institute, Trinity College Dublin, The University of DublinDublinIreland
- School of EngineeringTrinity College Dublin, The University of DublinDublinIreland
- Advanced Materials and Bioengineering Research (AMBER) CentreRoyal College of Surgeons in Ireland & Trinity College Dublin, The University of DublinDublinIreland
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Frauchiger DA, Chan SCW, Benneker LM, Gantenbein B. Intervertebral disc damage models in organ culture: a comparison of annulus fibrosus cross-incision versus punch model under complex loading. Eur Spine J 2018; 27:1785-1797. [PMID: 29789921 DOI: 10.1007/s00586-018-5638-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 05/10/2018] [Accepted: 05/14/2018] [Indexed: 11/25/2022]
Abstract
PURPOSE Comparison of two annulus fibrosus injury models that mimic intervertebral disc (IVD) herniation, enabling the study of IVD behaviour under three loading regimes in a bovine organ culture model. METHODS An injury was induced by custom-designed cross-incision tool or a 2-mm biopsy punch in IVDs. Discs were cultured for 14 days under (1) complex (compression and torsion), (2) static, and (3) no load. Disc height, mitochondrial activity, DNA and glycosaminoglycan (GAG) contents, and disc stiffness under complex load were determined. Further, gene expression and histology analysis were performed. RESULTS While both injury models did not change the compressional stiffness of IVDs, cross-incision decreased disc height under complex load. Moreover, under complex load, the biopsy punch injury induced down-regulation of several anabolic, catabol ic, and inflammatory genes, whereas cross-incision did not significantly differ from control discs. However, DNA and GAG contents were in the range of the healthy control discs for both injury models but did show lower contents under no load and static load. Injury side and contralateral side of the IVD showed a similar behaviour on the biochemical assays tested. CONCLUSION Compressional stiffness, GAG and DNA contents, did not differ between injury models under complex load. This behaviour was partially attributed to the positive influence of complex loading on matrix regeneration and cell viability. However, disc height was reduced for the cross-incision. Relative gene expression changes of the inflammatory and anabolic genes for the biopsy punch approach might indicate that induced damage was too intense to trigger any inflammatory or repair response. These slides can be retrieved under Electronic Supplementary Material.
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Affiliation(s)
- Daniela A Frauchiger
- Tissue and Organ Mechanobiology, Institute for Surgical Technology and Biomechanics, University of Bern, Stauffacherstrasse 78, 3014, Bern, Switzerland
| | - Samantha C W Chan
- Tissue and Organ Mechanobiology, Institute for Surgical Technology and Biomechanics, University of Bern, Stauffacherstrasse 78, 3014, Bern, Switzerland
| | - Lorin M Benneker
- Department of Orthopedic Surgery and Traumatology, Insel University Hospital, University of Bern, Freiburgstrasse 4, 3010, Bern, Switzerland
| | - Benjamin Gantenbein
- Tissue and Organ Mechanobiology, Institute for Surgical Technology and Biomechanics, University of Bern, Stauffacherstrasse 78, 3014, Bern, Switzerland.
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Zvicer J, Obradovic B. Bioreactors with hydrostatic pressures imitating physiological environments in intervertebral discs. J Tissue Eng Regen Med 2017; 12:529-545. [PMID: 28763577 DOI: 10.1002/term.2533] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 06/27/2017] [Accepted: 07/27/2017] [Indexed: 12/28/2022]
Abstract
Intervertebral discs are normally exposed to a variety of loads and stresses but hydrostatic pressure (HP) could be the main biosignal for chondrogenic cell differentiation and maintenance of this tissue. Although there are simple approaches to intermittently expose cell cultures to HP in separate material testing devices, utilization of biomimetic bioreactors aiming to provide in vitro conditions mimicking those found in vivo, attracts special attention. However, design of such bioreactors is complex due to the requirement of high HP magnitudes (up to 3 MPa) applied in different regimes mimicking pressures arising in intervertebral disc during normal daily activities. Furthermore, efficient mass transfer has to be facilitated to cells within 3D scaffolds, and the engineering challenges include avoidance or removal of gas bubbles in the culture medium before pressurization as well as selection of appropriate, biocompatible construction materials and maintenance of sterility during cultivation. Here, we review approaches to induce HP in 2D and 3D cell cultures categorized into 5 groups: (I) discontinuous systems with direct pressurization of the cultivation medium by a piston, (II) discontinuous systems with indirect pressurization by a compression fluid, (III) continuous systems with direct pressurization of the cultivation medium, static culture, (IV) continuous systems with culture perfusion, and (V) systems applying HP in conjunction with other physical signals. Although the complexity is increasing as additional features are added to the systems, the need to understand HP effects on cells and tissues in a physiologically relevant, yet precisely controlled, environment together with current technological advancements are leading towards innovative bioreactor solutions.
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Affiliation(s)
- Jovana Zvicer
- Faculty of Technology and Metallurgy, University of Belgrade, Belgrade, Serbia
| | - Bojana Obradovic
- Faculty of Technology and Metallurgy, University of Belgrade, Belgrade, Serbia
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