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Rivera Tapia ED, Meakin JR, Holsgrove TP. A novel in-vitro model of intervertebral disc degeneration using hyperphysiological loading. J Biomech 2024; 167:112068. [PMID: 38582004 DOI: 10.1016/j.jbiomech.2024.112068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 03/25/2024] [Accepted: 03/28/2024] [Indexed: 04/08/2024]
Abstract
Intervertebral disc (IVD) degeneration includes changes in tissue biomechanics, physical attributes, biochemical composition, disc microstructure, and cellularity, which can all affect the normal function of the IVD, and ultimately may lead to pain. The purpose of this research was to develop an in-vitro model of degeneration that includes the evaluation of physical, biomechanical, and structural parameters, and that does so over several load/recovery periods. Hyperphysiological loading was used as the degenerative initiator with three experimental groups employed using bovine coccygeal IVD specimens: Control; Single-Overload; and Double-Overload. An equilibrium stage comprising a static load followed by two load/recovery periods was followed by six further load/recovery periods. In the Control group all load/recovery periods were the same, comprising physiological cyclic loading. The overload groups differed in that hyperphysiological loading was applied during the 4th loading period (Single-Overload), or the 4th and 5th loading period (Double-Overload). Overloading led to a significant reduction in disc height compared to the Control group, which was not recovered in subsequent physiological load/recovery periods. However, there were no significant changes in stiffness. Overloading also led to significantly more microstructural damage compared to the Control group. Taking all outcome measures into account, the overload groups were evaluated as replicating clinically relevant aspects of moderate IVD degeneration. Further research into a potential dose-effect, and how more severe degeneration can be replicated would provide a model with the potential to evaluate new treatments and interventions for different stages of IVD degeneration.
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Affiliation(s)
- E D Rivera Tapia
- Department of Engineering, Faculty of Environment, Science and Economy, University of Exeter, Exeter, United Kingdom
| | - J R Meakin
- Department of Physics and Astronomy, Faculty of Environment, Science and Economy, University of Exeter, Exeter, United Kingdom
| | - T P Holsgrove
- Department of Engineering, Faculty of Environment, Science and Economy, University of Exeter, Exeter, United Kingdom.
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Lazaro-Pacheco D, Mohseni M, Rudd S, Cooper-White J, Holsgrove TP. The role of biomechanical factors in models of intervertebral disc degeneration across multiple length scales. APL Bioeng 2023; 7:021501. [PMID: 37180733 PMCID: PMC10168717 DOI: 10.1063/5.0137698] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 04/24/2023] [Indexed: 05/16/2023] Open
Abstract
Low back pain is the leading cause of disability, producing a substantial socio-economic burden on healthcare systems worldwide. Intervertebral disc (IVD) degeneration is a primary cause of lower back pain, and while regenerative therapies aimed at full functional recovery of the disc have been developed in recent years, no commercially available, approved devices or therapies for the regeneration of the IVD currently exist. In the development of these new approaches, numerous models for mechanical stimulation and preclinical assessment, including in vitro cell studies using microfluidics, ex vivo organ studies coupled with bioreactors and mechanical testing rigs, and in vivo testing in a variety of large and small animals, have emerged. These approaches have provided different capabilities, certainly improving the preclinical evaluation of these regenerative therapies, but challenges within the research environment, and compromises relating to non-representative mechanical stimulation and unrealistic test conditions, remain to be resolved. In this review, insights into the ideal characteristics of a disc model for the testing of IVD regenerative approaches are first assessed. Key learnings from in vivo, ex vivo, and in vitro IVD models under mechanical loading stimulation to date are presented alongside the merits and limitations of each model based on the physiological resemblance to the human IVD environment (biological and mechanical) as well as the possible feedback and output measurements for each approach. When moving from simplified in vitro models to ex vivo and in vivo approaches, the complexity increases resulting in less controllable models but providing a better representation of the physiological environment. Although cost, time, and ethical constraints are dependent on each approach, they escalate with the model complexity. These constraints are discussed and weighted as part of the characteristics of each model.
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Affiliation(s)
- Daniela Lazaro-Pacheco
- Department of Engineering, University of Exeter, Harrison Building, Streatham Campus, North Park Road, Exeter EX4 4QF, United Kingdom
| | - Mina Mohseni
- School of Chemical Engineering, The University of Queensland, St. Lucia QLD 4072, Australia
| | - Samuel Rudd
- School of Chemical Engineering, The University of Queensland, St. Lucia QLD 4072, Australia
| | | | - Timothy Patrick Holsgrove
- Department of Engineering, University of Exeter, Harrison Building, Streatham Campus, North Park Road, Exeter EX4 4QF, United Kingdom
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Li X, Zhang Q, Yu SM, Li Y. The Chemistry and Biology of Collagen Hybridization. J Am Chem Soc 2023; 145:10901-10916. [PMID: 37158802 PMCID: PMC10789224 DOI: 10.1021/jacs.3c00713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Collagen provides mechanical and biological support for virtually all human tissues in the extracellular matrix (ECM). Its defining molecular structure, the triple-helix, could be damaged and denatured in disease and injuries. To probe collagen damage, the concept of collagen hybridization has been proposed, revised, and validated through a series of investigations reported as early as 1973: a collagen-mimicking peptide strand may form a hybrid triple-helix with the denatured chains of natural collagen but not the intact triple-helical collagen proteins, enabling assessment of proteolytic degradation or mechanical disruption to collagen within a tissue-of-interest. Here we describe the concept and development of collagen hybridization, summarize the decades of chemical investigations on rules underlying the collagen triple-helix folding, and discuss the growing biomedical evidence on collagen denaturation as a previously overlooked ECM signature for an array of conditions involving pathological tissue remodeling and mechanical injuries. Finally, we propose a series of emerging questions regarding the chemical and biological nature of collagen denaturation and highlight the diagnostic and therapeutic opportunities from its targeting.
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Affiliation(s)
- Xiaojing Li
- Guangdong Provincial Engineering Research Center of Molecular Imaging, Department of Radiology, Cardiac Surgery and Structural Heart Disease Unit of Cardiovascular Center, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, 519000, China
| | - Qi Zhang
- Guangdong Provincial Engineering Research Center of Molecular Imaging, Department of Radiology, Cardiac Surgery and Structural Heart Disease Unit of Cardiovascular Center, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, 519000, China
| | - S. Michael Yu
- Department of Biomedical Engineering, Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Yang Li
- Guangdong Provincial Engineering Research Center of Molecular Imaging, Department of Radiology, Cardiac Surgery and Structural Heart Disease Unit of Cardiovascular Center, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, 519000, China
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In-vitro models of disc degeneration - A review of methods and clinical relevance. J Biomech 2022; 142:111260. [PMID: 36027637 DOI: 10.1016/j.jbiomech.2022.111260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 07/22/2022] [Accepted: 08/11/2022] [Indexed: 11/21/2022]
Abstract
The intervertebral disc (IVD) provides flexibility, acts as a shock absorber, and transmits load. Degeneration of the IVD includes alterations in the biomechanics, extracellular matrix (ECM), and cellular activity. These changes are not always perceived, however, IVD degeneration can lead to severe health problems including long-term disability. To understand the pathogenesis of IVD degeneration and suitable testing methods for emerging treatments and therapies, this review documents in-vitro models of IVD degeneration including physical disruption, hyperphysiological loading, ECM degradation by enzyme digestion, or a combination of these methods. This paper reviews and critically analyses the models of degeneration published since the year 2000 in either in human or animal specimens. The results are categorised in terms of the IVD biomechanics, physical attributes, ECM composition, tissue damage and cellularity to evaluate the models with respect to natural human degeneration, and to provide recommendations for clinically relevant models for the various stages of degeneration. There is no one model that replicates the wide range of degenerative changes that occur as part of normal degeneration. However, cyclic overloading replicates many aspects of degeneration, with the advantage of a dose-response allowing the tuning of damage initiated. Models of severe degeneration are currently lacking, but there is potential that combining cyclic overloading and enzymatic digestion will provide model that closely resembles human IVD degeneration. This will provide an effective way to investigate the effects of severe degeneration, and the evaluation of treatments for the IVD, which would generally be indicated at this advanced stage of degeneration.
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Kim AG, Kim TW, Kwon WK, Lee KH, Jeong S, Hwang MH, Choi H. Microfluidic Chip with Low Constant-Current Stimulation (LCCS) Platform: Human Nucleus Pulposus Degeneration In Vitro Model for Symptomatic Intervertebral Disc. MICROMACHINES 2021; 12:1291. [PMID: 34832700 PMCID: PMC8621874 DOI: 10.3390/mi12111291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 10/15/2021] [Accepted: 10/18/2021] [Indexed: 01/07/2023]
Abstract
Intervertebral disc (IVD) degeneration is a major cause of low back pain (LBP) in the lumbar spine. This phenomenon is caused by several processes, including matrix degradation in IVD tissues, which is mediated by matrix metalloproteinases (MMPs) and inflammatory responses, which can be mediated by interactions among immune cells, such as macrophages and IVD cells. In particular, interleukin (IL)-1 beta (β), which is a master regulator secreted by macrophages, mediates the inflammatory response in nucleus pulposus cells (NP) and plays a significant role in the development or progression of diseases. In this study, we developed a custom electrical stimulation (ES) platform that can apply low-constant-current stimulation (LCCS) signals to microfluidic chips. Using this platform, we examined the effects of LCCS on IL-1β-mediated inflammatory NP cells, administered at various currents (5, 10, 20, 50, and 100 μA at 200 Hz). Our results showed that the inflammatory response, induced by IL-1β in human NP cells, was successfully established. Furthermore, 5, 10, 20, and 100 μA LCCS positively modulated inflamed human NP cells' morphological phenotype and kinetic properties. LCCS could affect the treatment of degenerative diseases, revealing the applicability of the LCCS platform for basic research of electroceuticals.
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Affiliation(s)
- An-Gi Kim
- Department of Medical Sciences, Graduate School of Medicine, Korea University, Seoul 08308, Korea; (A.-G.K.); (T.-W.K.)
| | - Tae-Won Kim
- Department of Medical Sciences, Graduate School of Medicine, Korea University, Seoul 08308, Korea; (A.-G.K.); (T.-W.K.)
| | - Woo-Keun Kwon
- Department of Neurosurgery, College of Medicine, Korea University Guro Hospital, Seoul 08308, Korea;
| | - Kwang-Ho Lee
- Division of Mechanical and Biomedical, Mechatronics, and Materials Science and Engineering, College of Engineering, Kangwon National University, Chuncheon 24341, Korea;
| | - Sehoon Jeong
- Department of Healthcare Information Technology, Inje University, Gimhae 50834, Korea;
| | - Min-Ho Hwang
- Department of Medical Sciences, Graduate School of Medicine, Korea University, Seoul 08308, Korea; (A.-G.K.); (T.-W.K.)
| | - Hyuk Choi
- Department of Medical Sciences, Graduate School of Medicine, Korea University, Seoul 08308, Korea; (A.-G.K.); (T.-W.K.)
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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] [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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McDonnell EE, Buckley CT. Investigating the physiological relevance of ex vivo disc organ culture nutrient microenvironments using in silico modeling and experimental validation. JOR Spine 2021; 4:e1141. [PMID: 34337330 PMCID: PMC8313156 DOI: 10.1002/jsp2.1141] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/22/2021] [Accepted: 01/28/2021] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Ex vivo disc organ culture systems have become a valuable tool for the development and pre-clinical testing of potential intervertebral disc (IVD) regeneration strategies. Bovine caudal discs have been widely selected due to their large availability and comparability to human IVDs in terms of size and biochemical composition. However, despite their extensive use, it remains to be elucidated whether their nutrient microenvironment is comparable to human degeneration. AIMS This work aims to create the first experimentally validated in silico model which can be used to predict and characterize the metabolite concentrations within ex vivo culture systems. MATERIALS & METHODS Finite element models of cultured discs governed by previously established coupled reaction-diffusion equations were created using COMSOL Multiphysics. Experimental validation was performed by measuring oxygen, glucose and pH levels within discs cultured for 7 days, in a static compression bioreactor. RESULTS The in silico model was successfully validated through good agreement between the predicted and experimentally measured concentrations. For an ex vivo organ cultured in high glucose medium (4.5 g/L or 25 mM) and normoxia, a larger bovine caudal disc (Cd1-2 to Cd3-4) had a central concentration of ~2.6 %O2, ~8 mM of glucose and a pH value of 6.7, while the smallest caudal discs investigated (Cd6-7 and Cd7-8), had a central concentration of ~6.5 %O2, ~12 mM of glucose and a pH value of 6.9. DISCUSSION This work advances the knowledge of ex vivo disc culture microenvironments and highlights a critical need for optimization and standardization of culturing conditions. CONCLUSION Ultimately, for assessment of cell-based therapies and successful clinical translation based on nutritional demands, it is imperative that the critical metabolite values within organ cultures (minimum glucose, oxygen and pH values) are physiologically relevant and comparable to the stages of human degeneration.
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Affiliation(s)
- Emily E. McDonnell
- Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College DublinThe University of DublinDublinIreland
- Discipline of Mechanical, Manufacturing and Biomedical Engineering, School of Engineering, Trinity College DublinThe University of DublinDublinIreland
| | - Conor T. Buckley
- Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College DublinThe University of DublinDublinIreland
- Discipline of Mechanical, Manufacturing and Biomedical Engineering, School of Engineering, Trinity College DublinThe University of DublinDublinIreland
- Advanced Materials and Bioengineering Research (AMBER) Centre, Royal College of Surgeons in Ireland and Trinity College DublinThe University of DublinDublinIreland
- Tissue Engineering Research Group, Department of Anatomy and Regenerative MedicineRoyal College of Surgeons in IrelandDublinIreland
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