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Barajaa MA, Otsuka T, Ghosh D, Kan HM, Laurencin CT. Development of porcine skeletal muscle extracellular matrix-derived hydrogels with improved properties and low immunogenicity. Proc Natl Acad Sci U S A 2024; 121:e2322822121. [PMID: 38687784 PMCID: PMC11087813 DOI: 10.1073/pnas.2322822121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Accepted: 03/18/2024] [Indexed: 05/02/2024] Open
Abstract
Hydrogels derived from decellularized extracellular matrices (ECM) of animal origin show immense potential for regenerative applications due to their excellent cytocompatibility and biomimetic properties. Despite these benefits, the impact of decellularization protocols on the properties and immunogenicity of these hydrogels remains relatively unexplored. In this study, porcine skeletal muscle ECM (smECM) underwent decellularization using mechanical disruption (MD) and two commonly employed decellularization detergents, sodium deoxycholate (SDC) or Triton X-100. To mitigate immunogenicity associated with animal-derived ECM, all decellularized tissues were enzymatically treated with α-galactosidase to cleave the primary xenoantigen-the α-Gal antigen. Subsequently, the impact of the different decellularization protocols on the resultant hydrogels was thoroughly investigated. All methods significantly reduced total DNA content in hydrogels. Moreover, α-galactosidase treatment was crucial for cleaving α-Gal antigens, suggesting that conventional decellularization methods alone are insufficient. MD preserved total protein, collagen, sulfated glycosaminoglycan, laminin, fibronectin, and growth factors more efficiently than other protocols. The decellularization method impacted hydrogel gelation kinetics and ultrastructure, as confirmed by turbidimetric and scanning electron microscopy analyses. MD hydrogels demonstrated high cytocompatibility, supporting satellite stem cell recruitment, growth, and differentiation into multinucleated myofibers. In contrast, the SDC and Triton X-100 protocols exhibited cytotoxicity. Comprehensive in vivo immunogenicity assessments in a subcutaneous xenotransplantation model revealed MD hydrogels' biocompatibility and low immunogenicity. These findings highlight the significant influence of the decellularization protocol on hydrogel properties. Our results suggest that combining MD with α-galactosidase treatment is an efficient method for preparing low-immunogenic smECM-derived hydrogels with enhanced properties for skeletal muscle regenerative engineering and clinical applications.
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Affiliation(s)
- Mohammed A. Barajaa
- Department of Biomedical Engineering, College of Engineering, Imam Abdulrahman Bin Faisal University, Dammam34212, Saudi Arabia
| | - Takayoshi Otsuka
- The Cato T. Laurencin Institute for Regenerative Engineering, University of Connecticut, Farmington, CT06030
| | - Debolina Ghosh
- The Cato T. Laurencin Institute for Regenerative Engineering, University of Connecticut, Farmington, CT06030
| | - Ho-Man Kan
- The Cato T. Laurencin Institute for Regenerative Engineering, University of Connecticut, Farmington, CT06030
| | - Cato T. Laurencin
- The Cato T. Laurencin Institute for Regenerative Engineering, University of Connecticut, Farmington, CT06030
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT06269
- Department of Orthopedic Surgery, University of Connecticut Health Center, Farmington, CT06030
- Department of Materials Science & Engineering, University of Connecticut, Storrs, CT06269
- Department of Chemical & Bimolecular Engineering, University of Connecticut, Storrs, CT06269
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2
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Hague JP, Andrews AE, Dickinson H. High-throughput design of cultured tissue moulds using a biophysical model: optimising cell alignment. Phys Biol 2023; 20:066006. [PMID: 37899639 DOI: 10.1088/1478-3975/ad0276] [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: 08/03/2023] [Accepted: 10/11/2023] [Indexed: 10/31/2023]
Abstract
The technique presented here identifies tethered mould designs, optimised for growing cultured tissue with very highly-aligned cells. It is based on a microscopic biophysical model for polarised cellular hydrogels. There is an unmet need for tools to assist mould and scaffold designs for the growth of cultured tissues with bespoke cell organisations, that can be used in applications such as regenerative medicine, drug screening and cultured meat. High-throughput biophysical calculations were made for a wide variety of computer-generated moulds, with cell-matrix interactions and tissue-scale forces simulated using a contractile network dipole orientation model. Elongated moulds with central broadening and one of the following tethering strategies are found to lead to highly-aligned cells: (1) tethers placed within the bilateral protrusions resulting from an indentation on the short edge, to guide alignment (2) tethers placed within a single vertex to shrink the available space for misalignment. As such, proof-of-concept has been shown for mould and tethered scaffold design based on a recently developed biophysical model. The approach is applicable to a broad range of cell types that align in tissues and is extensible for 3D scaffolds.
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Affiliation(s)
- James P Hague
- School of Physical Sciences, The Open University, Milton Keynes, MK7 6AA, United Kingdom
| | - Allison E Andrews
- School of Physical Sciences, The Open University, Milton Keynes, MK7 6AA, United Kingdom
| | - Hugh Dickinson
- School of Physical Sciences, The Open University, Milton Keynes, MK7 6AA, United Kingdom
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3
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Kellaway SC, Roberton V, Jones JN, Loczenski R, Phillips JB, White LJ. Engineered neural tissue made using hydrogels derived from decellularised tissues for the regeneration of peripheral nerves. Acta Biomater 2023; 157:124-136. [PMID: 36494008 DOI: 10.1016/j.actbio.2022.12.003] [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: 08/02/2022] [Revised: 11/10/2022] [Accepted: 12/02/2022] [Indexed: 12/12/2022]
Abstract
Engineered neural tissue (EngNT) promotes in vivo axonal regeneration. Decellularised materials (dECM) are complex biologic scaffolds that can improve the cellular environment and also encourage positive tissue remodelling in vivo. We hypothesised that we could incorporate a hydrogel derived from a decellularised tissue (dECMh) into EngNT, thereby providing an alternative to the currently used purified collagen I hydrogel for the first time. Decellularisation was carried out on bone (B-ECM), liver (LIV-ECM), and small intestinal (SIS-ECM) tissues and the resultant dECM was biochemically and mechanically characterised. dECMh differed in mechanical and biochemical properties that likely had an effect on Schwann cell behaviour observed in metabolic activity and contraction profiles. Cellular alignment was observed in tethered moulds within the B-ECM and SIS-ECM derived hydrogels only. No difference was observed in dorsal root ganglia (DRG) neurite extension between the dECMh groups and collagen I groups when applied as a coverslip coating, however, when DRG were seeded atop EngNT constructs, only the B-ECM derived EngNT performed similarly to collagen I derived EngNT. B-ECM EngNT further exhibited similar axonal regeneration to collagen I EngNT in a 10 mm gap rat sciatic nerve injury model after 4 weeks. Our results have shown that various dECMh can be utilised to produce EngNT that can promote neurite extension in vitro and axonal regeneration in vivo. STATEMENT OF SIGNIFICANCE: Nerve autografts are undesirable due to the sacrifice of a patient's own nerve tissue to repair injuries. Engineered neural tissue (EngNT) is a type of living artificial tissue that has been developed to overcome this. To date, only a collagen hydrogel has been shown to be effective in the production and utilisation of EngNT in animal models. Hydrogels may be made from decellularised extracellular matrix derived from many tissues. In this study we showed that hydrogels from various tissues may be used to create EngNT and one was shown to comparable to the currently used collagen based EngNT in a rat sciatic nerve injry model.
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Affiliation(s)
- Simon C Kellaway
- Centre for Nerve Engineering, University College London, UK; Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, Biodiscovery Institute, University of Nottingham, University Park, Nottingham, NG7 2RD, UK; Department of Pharmacology, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK; Biodiscovery Institute, University of Nottingham, University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
| | - Victoria Roberton
- Centre for Nerve Engineering, University College London, UK; Department of Pharmacology, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Joshua N Jones
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, Biodiscovery Institute, University of Nottingham, University Park, Nottingham, NG7 2RD, UK; Biodiscovery Institute, University of Nottingham, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Rabea Loczenski
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, Biodiscovery Institute, University of Nottingham, University Park, Nottingham, NG7 2RD, UK; Biodiscovery Institute, University of Nottingham, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - James B Phillips
- Centre for Nerve Engineering, University College London, UK; Department of Pharmacology, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Lisa J White
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, Biodiscovery Institute, University of Nottingham, University Park, Nottingham, NG7 2RD, UK; Biodiscovery Institute, University of Nottingham, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
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4
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Zhang Q, Wang P, Fang X, Lin F, Fang J, Xiong C. Collagen gel contraction assays: From modelling wound healing to quantifying cellular interactions with three-dimensional extracellular matrices. Eur J Cell Biol 2022; 101:151253. [PMID: 35785635 DOI: 10.1016/j.ejcb.2022.151253] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2021] [Revised: 06/06/2022] [Accepted: 06/24/2022] [Indexed: 12/12/2022] Open
Abstract
Cells respond to and actively remodel the extracellular matrix (ECM). The dynamic and bidirectional interaction between cells and ECM, especially their mechanical interactions, has been found to play an essential role in triggering a series of complex biochemical and biomechanical signal pathways and in regulating cellular functions and behaviours. The collagen gel contraction assay (CGCA) is a widely used method to investigate cell-ECM interactions in 3D environments and provides a mechanically associated readout reflecting 3D cellular contractility. In this review, we summarize various versions of CGCA, with an emphasis on recent high-throughput and low-consumption CGCA techniques. More importantly, we focus on the technique of force monitoring during the contraction of collagen gel, which provides a quantitative characterization of the overall forces generated by all the resident cells in the collagen hydrogel. Accordingly, we present recent biological applications of the CGCA, which have expanded from the initial wound healing model to other studies concerning cell-ECM interactions, including fibrosis, cancer, tissue repair and the preparation of biomimetic microtissues.
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Affiliation(s)
- Qing Zhang
- Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871, China
| | - Pudi Wang
- Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871, China
| | - Xu Fang
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Feng Lin
- Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou 325000, China
| | - Jing Fang
- Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871, China; Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Chunyang Xiong
- Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871, China; Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China; Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou 325000, China.
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5
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Peng Q, Gorter WS, Vermolen FJ. Comparison between a phenomenological approach and a morphoelasticity approach regarding the displacement of extracellular matrix. Biomech Model Mechanobiol 2022; 21:919-935. [PMID: 35403944 PMCID: PMC9132877 DOI: 10.1007/s10237-022-01568-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 02/25/2022] [Indexed: 11/30/2022]
Abstract
Plastic (permanent) deformations were earlier, modeled by a phenomenological model in Peng and Vermolen (Biomech Model Mechanobiol 19(6):2525–2551, 2020). In this manusctipt, we consider a more physics-based formulation that is based on morphoelasticity. We firstly introduce the morphoelasticity approach and investigate the impact of various input variables on the output parameters by sensitivity analysis. A comparison of both model formulations shows that both models give similar computational results. Furthermore, we carry out Monte Carlo simulations of the skin contraction model containing the morphoelasticity approach. Most statistical correlations from the two models are similar, however, the impact of the collagen density on the severeness of contraction is larger for the morphoelasticity model than for the phenomenological model.
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Affiliation(s)
- Q Peng
- Mathematical Institute, Leiden University, 2333 CA, Niels Bohrweg, The Netherlands. .,Delft Institute of Applied Mathematics, Delft University of Technology, Mekelweg 4, 2628 CD, Delft, The Netherlands. .,Computational Mathematics Group, Discipline group Mathematics and statistics, Faculty of Science, Hasselt University, Campus Diepenbeek, Agoralaan Gebouw D, BE 3590, Diepenbeek, Belgium.
| | - W S Gorter
- Delft Institute of Applied Mathematics, Delft University of Technology, Mekelweg 4, 2628 CD, Delft, The Netherlands
| | - F J Vermolen
- Delft Institute of Applied Mathematics, Delft University of Technology, Mekelweg 4, 2628 CD, Delft, The Netherlands.,Computational Mathematics Group, Discipline group Mathematics and statistics, Faculty of Science, Hasselt University, Campus Diepenbeek, Agoralaan Gebouw D, BE 3590, Diepenbeek, Belgium
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6
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The contracture-in-a-well. An in vitro model distinguishes bulk and interfacial processes of irreversible (fibrotic) cell-mediated contraction. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2022; 133:112661. [DOI: 10.1016/j.msec.2022.112661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 01/04/2022] [Accepted: 01/07/2022] [Indexed: 11/21/2022]
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7
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Lei Y, Bortolin L, Benesch-Lee F, Oguntolu T, Dong Z, Bondah N, Billiar K. Hyaluronic acid regulates heart valve interstitial cell contraction in fibrin-based scaffolds. Acta Biomater 2021; 136:124-136. [PMID: 34592445 DOI: 10.1016/j.actbio.2021.09.046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 09/23/2021] [Accepted: 09/23/2021] [Indexed: 11/30/2022]
Abstract
Heart valve disease is associated with high morbidity and mortality worldwide resulting in hundreds of thousands of heart valve replacements each year. Tissue engineered heart valves (TEHVs) have the potential to overcome the major limitations of traditional replacement valves; however, leaflet retraction has led to the failure of TEHVs in preclinical studies. As native unmodified hyaluronic acid (HA) is known to promote healthy tissue development in native heart valves, we hypothesize that adding unmodified HA to fibrin-based scaffolds common to tissue engineering will reduce retraction by increasing cell-scaffold interactions and density of the scaffolds. Using a custom high-throughput culture system, we found that incorporating HA into millimeter-scale fibrin-based cell-populated scaffolds increases initial fiber diameter and cell-scaffold interactions, causing a cascade of mechanical, morphological, and cellular responses. These changes lead to higher levels of scaffold compaction and stiffness, increased cell alignment, and less bundling of fibrin fibers by the cells during culture. These effects significantly reduce scaffold retraction and total contractile force each by around 25%. These findings increase our understanding of how HA alters tissue remodeling and could inform the design of the next generation of tissue engineered heart valves to help reduce retraction. STATEMENT OF SIGNIFICANCE: Tissue engineered heart valves (TEHVs) have the potential to overcome the major limitations of traditional replacement valves; however, leaflet retraction induced by excessive myofibroblast activation has led to failure in preclinical studies. Developing valves are rich in hyaluronic acid (HA), which helps maintain a physiological environment for tissue remodeling without retraction. We hypothesized that adding unmodified HA to TEHVs would reduce retraction by increasing cell-scaffold interactions and density of the scaffolds. Using a high-throughput tissue culture platform, we demonstrate that HA incorporation into a fibrin-based scaffold can significantly reduce tissue retraction and total contractile force by increasing fiber bundling and altering cell-mediated matrix remodeling, therefore increasing gel density and stiffness. These finding increase our knowledge of native HA's effects within the extracellular matrix, and provide a new tool for TEHV design.
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Affiliation(s)
- Ying Lei
- Biomedical Engineering Department, Worcester Polytechnic Institute, Gateway Park 4008, 60 Prescott, Worcester, MA 01605, USA
| | - Luciano Bortolin
- Biomedical Engineering Department, Worcester Polytechnic Institute, Gateway Park 4008, 60 Prescott, Worcester, MA 01605, USA
| | - Frank Benesch-Lee
- Biomedical Engineering Department, Worcester Polytechnic Institute, Gateway Park 4008, 60 Prescott, Worcester, MA 01605, USA
| | - Teniola Oguntolu
- Biomedical Engineering Department, Worcester Polytechnic Institute, Gateway Park 4008, 60 Prescott, Worcester, MA 01605, USA
| | - Zhijie Dong
- Biomedical Engineering Department, Worcester Polytechnic Institute, Gateway Park 4008, 60 Prescott, Worcester, MA 01605, USA
| | - Narda Bondah
- Biomedical Engineering Department, Worcester Polytechnic Institute, Gateway Park 4008, 60 Prescott, Worcester, MA 01605, USA
| | - Kristen Billiar
- Biomedical Engineering Department, Worcester Polytechnic Institute, Gateway Park 4008, 60 Prescott, Worcester, MA 01605, USA.
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8
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Engineered neural tissue made using clinical-grade human neural stem cells supports regeneration in a long gap peripheral nerve injury model. Acta Biomater 2021; 135:203-213. [PMID: 34455110 DOI: 10.1016/j.actbio.2021.08.030] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 08/08/2021] [Accepted: 08/19/2021] [Indexed: 12/11/2022]
Abstract
A surgical autograft remains the clinical gold-standard therapy for gap repair following peripheral nerve injury, however, challenges remain with achieving full recovery and reducing donor-site morbidity. Engineered Neural Tissue (EngNT) manufactured using differentiated CTX0E03 human stem cells (EngNT-CTX) has been developed as a potential 'off the shelf' allogeneic autograft replacement. Ensheathed within a collagen membrane developed to facilitate biomechanical integration, EngNT-CTX was used to bridge a critical-length (15 mm) sciatic nerve gap injury in athymic nude rats. The effectiveness of EngNT-CTX was compared to an autograft using outcome measures that assessed neuronal regeneration and functional recovery at 8 and 16 weeks. At both time points EngNT-CTX restored electrophysiological nerve conduction and functional reinnervation of downstream muscles to the same extent as the autograft. Histological analysis confirmed that more motor neurons had successfully regenerated through the repair in EngNT-CTX in comparison to the autograft at 8 weeks, which was consistent with the electrophysiology, with the number of motor neurons similar in both groups by 16 weeks. The total number of neurons (motor + sensory) was greater in autografts than EngNT-CTX at 8 weeks, indicating that more sensory fibres may have sprouted in those animals at this time point. In conclusion, this study provides evidence to support the effectiveness of EngNT-CTX as a replacement for the nerve autograft, as the functional regeneration assessed through histological and electrophysiological outcome measures demonstrated equivalent performance. STATEMENT OF SIGNIFICANCE: Following injury a peripheral nerve has the capacity to regenerate naturally, however, in the case of severe damage where there is a gap the current gold-standard microsurgical intervention is an autograft. This is associated with serious limitations including tissue availability and donor-site morbidity. Tissue engineering aims to overcome these limitations by building a construct from therapeutic cells and biomaterials as a means to mimic and replace the autograft. In this study engineered neural tissue (EngNT) was manufactured using human stem cells (CTX) to bridge a critical-length gap injury. When compared to the autograft in an animal model the EngNT-CTX construct restored function to an equivalent or greater extent.
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9
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'EngNT' - Engineering live neural tissue for nerve replacement. Emerg Top Life Sci 2021; 5:699-703. [PMID: 34297065 PMCID: PMC8726050 DOI: 10.1042/etls20210085] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 07/06/2021] [Accepted: 07/13/2021] [Indexed: 11/17/2022]
Abstract
Peripheral nerve injury can result in severe long-term disability and current clinical approaches for repairing large gaps rely on the nerve autograft. Engineered Neural Tissue (EngNT) has been developed to provide living aligned therapeutic cells in a stabilised collagen hydrogel, mimicking the key features of the autograft. This Perspective article will introduce the field and discuss the current stage of translation, highlighting the key opportunities for commercial and clinical development.
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10
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Powell R, Eleftheriadou D, Kellaway S, Phillips JB. Natural Biomaterials as Instructive Engineered Microenvironments That Direct Cellular Function in Peripheral Nerve Tissue Engineering. Front Bioeng Biotechnol 2021; 9:674473. [PMID: 34113607 PMCID: PMC8185204 DOI: 10.3389/fbioe.2021.674473] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 04/16/2021] [Indexed: 12/25/2022] Open
Abstract
Nerve tissue function and regeneration depend on precise and well-synchronised spatial and temporal control of biological, physical, and chemotactic cues, which are provided by cellular components and the surrounding extracellular matrix. Therefore, natural biomaterials currently used in peripheral nerve tissue engineering are selected on the basis that they can act as instructive extracellular microenvironments. Despite emerging knowledge regarding cell-matrix interactions, the exact mechanisms through which these biomaterials alter the behaviour of the host and implanted cells, including neurons, Schwann cells and immune cells, remain largely unclear. Here, we review some of the physical processes by which natural biomaterials mimic the function of the extracellular matrix and regulate cellular behaviour. We also highlight some representative cases of controllable cell microenvironments developed by combining cell biology and tissue engineering principles.
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Affiliation(s)
- Rebecca Powell
- UCL Centre for Nerve Engineering, University College London, London, United Kingdom.,Department of Pharmacology, UCL School of Pharmacy, University College London, London, United Kingdom
| | - Despoina Eleftheriadou
- UCL Centre for Nerve Engineering, University College London, London, United Kingdom.,Department of Pharmacology, UCL School of Pharmacy, University College London, London, United Kingdom.,Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Simon Kellaway
- UCL Centre for Nerve Engineering, University College London, London, United Kingdom.,Department of Pharmacology, UCL School of Pharmacy, University College London, London, United Kingdom
| | - James B Phillips
- UCL Centre for Nerve Engineering, University College London, London, United Kingdom.,Department of Pharmacology, UCL School of Pharmacy, University College London, London, United Kingdom
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11
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Muangsanit P, Roberton V, Costa E, Phillips JB. Engineered aligned endothelial cell structures in tethered collagen hydrogels promote peripheral nerve regeneration. Acta Biomater 2021; 126:224-237. [PMID: 33766800 DOI: 10.1016/j.actbio.2021.03.039] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 03/01/2021] [Accepted: 03/16/2021] [Indexed: 02/07/2023]
Abstract
Vascularisation is important in nerve tissue engineering to provide blood supply and nutrients for long-term survival of implanted cells. Furthermore, blood vessels in regenerating nerves have been shown to serve as tracks for Schwann cells to migrate along and thus form Bands of Büngner which promote axonal regeneration. In this study, we have developed tissue-engineered constructs containing aligned endothelial cells, or co-cultures of both endothelial cells and Schwann cells to test whether these structures could promote regeneration across peripheral nerve gaps. Type I rat tail collagen gels containing HUVECs (Human Umbilical Vein Endothelial Cells, 4 × 106 cells/ml) were cast in perforated tethering silicone conduits to facilitate cellular self-alignment and tube formation for 4 days of culture. For co-culture constructs, optimal tube formation and cellular alignment was achieved with a ratio of 4:0.5 × 106 cells/ml (HUVECs:Schwann cells). An in vivo test of the engineered constructs to bridge a 10 mm gap in rat sciatic nerves for 4 weeks revealed that constructs containing only HUVECs significantly promoted axonal regeneration and vascularisation across the gap, as compared to conventional aligned Schwann cell constructs and those containing co-cultured HUVECs and Schwann cells. Our results suggest that tissue-engineered constructs containing aligned endothelial cells within collagen matrix could be good candidates to treat peripheral nerve injury. STATEMENT OF SIGNIFICANCE: Nerve tissue engineering provides a potential way to overcome the limitations associated with current clinical grafting techniques for the repair of severe peripheral nerve injuries. However, the therapeutic cells within engineered nerve tissue require effective vascularisation in order to survive. This work therefore aimed to develop engineered nerve constructs containing aligned tube-like structures made from endothelial cells. Not only did this provide a method to improve vascularisation, it demonstrated for the first time that aligned endothelial cells can outperform Schwann cells in promoting nerve regeneration in the rat sciatic nerve model. This has introduced the concept of developing pre-vascularised engineered nerve tissues, and indicated the potential usefulness of endothelial cell structures in tissue engineering for peripheral nerve repair.
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Affiliation(s)
- Papon Muangsanit
- Department of Biomaterials and Tissue Engineering, Eastman Dental Institute, University College London, 256 Grays Inn Rd, London WC1X8LD, United Kingdom; UCL Centre for Nerve Engineering, University College London, London, United Kingdom; Department of Pharmacology, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, Bloomsbury, London WC1N 1AX, United Kingdom.
| | - Victoria Roberton
- UCL Centre for Nerve Engineering, University College London, London, United Kingdom; Department of Pharmacology, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, Bloomsbury, London WC1N 1AX, United Kingdom
| | - Eleni Costa
- Department of Pharmacology, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, Bloomsbury, London WC1N 1AX, United Kingdom
| | - James B Phillips
- UCL Centre for Nerve Engineering, University College London, London, United Kingdom; Department of Pharmacology, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, Bloomsbury, London WC1N 1AX, United Kingdom
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12
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Powell R, Phillips JB. Engineered Tissues Made from Human iPSC-Derived Schwann Cells for Investigating Peripheral Nerve Regeneration In Vitro. Methods Mol Biol 2021; 2269:245-254. [PMID: 33687684 DOI: 10.1007/978-1-0716-1225-5_17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2023]
Abstract
Peripheral nerves have a limited ability to regenerate and current clinical approaches involving microsurgery give suboptimal recovery. Engineered tissues using aligned cellular collagen hydrogels can be used as in vitro models through the incorporation of human Schwann cells. However, primary human Schwann cells are difficult to obtain and can be challenging to culture. The ability to generate Schwann cells from human-induced pluripotent stem cells (hiPSCs) provides a more reliable cell source for modeling peripheral nerve tissue. Here, we describe protocols for generating hiPSC-derived Schwann cells and incorporating them into 3D engineered tissue culture models for peripheral nerve research.
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Affiliation(s)
- Rebecca Powell
- UCL Centre for Nerve Engineering, Department of Pharmacology, UCL School of Pharmacy, University College London, London, UK
| | - James B Phillips
- UCL Centre for Nerve Engineering, Department of Pharmacology, UCL School of Pharmacy, University College London, London, UK.
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13
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Muangsanit P, Day A, Dimiou S, Ataç AF, Kayal C, Park H, Nazhat SN, Phillips JB. Rapidly formed stable and aligned dense collagen gels seeded with Schwann cells support peripheral nerve regeneration. J Neural Eng 2020; 17:046036. [DOI: 10.1088/1741-2552/abaa9c] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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14
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Vagaska B, Gillham O, Ferretti P. Modelling human CNS injury with human neural stem cells in 2- and 3-Dimensional cultures. Sci Rep 2020; 10:6785. [PMID: 32321995 PMCID: PMC7176653 DOI: 10.1038/s41598-020-62906-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 03/16/2020] [Indexed: 12/16/2022] Open
Abstract
The adult human central nervous system (CNS) has very limited regenerative capability, and injury at the cellular and molecular level cannot be studied in vivo. Modelling neural damage in human systems is crucial to identifying species-specific responses to injury and potentially neurotoxic compounds leading to development of more effective neuroprotective agents. Hence we developed human neural stem cell (hNSC) 3-dimensional (3D) cultures and tested their potential for modelling neural insults, including hypoxic-ischaemic and Ca2+-dependent injury. Standard 3D conditions for rodent cells support neuroblastoma lines used as human CNS models, but not hNSCs, but in all cases changes in culture architecture alter gene expression. Importantly, response to damage differs in 2D and 3D cultures and this is not due to reduced drug accessibility. Together, this study highlights the impact of culture cytoarchitecture on hNSC phenotype and damage response, indicating that 3D models may be better predictors of in vivo response to damage and compound toxicity.
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Affiliation(s)
- Barbora Vagaska
- Stem Cells and Regenerative Medicine Section, UCL Great Ormond Street Institute of Child Health, University College London, London, WC1N 1EH, UK
| | - Olivia Gillham
- Stem Cells and Regenerative Medicine Section, UCL Great Ormond Street Institute of Child Health, University College London, London, WC1N 1EH, UK
| | - Patrizia Ferretti
- Stem Cells and Regenerative Medicine Section, UCL Great Ormond Street Institute of Child Health, University College London, London, WC1N 1EH, UK.
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15
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Muangsanit P, Shipley RJ, Phillips JB. Vascularization Strategies for Peripheral Nerve Tissue Engineering. Anat Rec (Hoboken) 2018; 301:1657-1667. [PMID: 30334363 PMCID: PMC6282999 DOI: 10.1002/ar.23919] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 03/07/2018] [Accepted: 04/05/2018] [Indexed: 12/21/2022]
Abstract
Vascularization plays a significant role in treating nerve injury, especially to avoid the central necrosis observed in nerve grafts for large and long nerve defects. It is known that sufficient vascularization can sustain cell survival and maintain cell integration within tissue‐engineered constructs. Several studies have also shown that vascularization affects nerve regeneration. Motivated by these studies, vascularized nerve grafts have been developed using various different techniques, although donor site morbidity and limited nerve supply remain significant drawbacks. Tissue engineering provides an exciting alternative approach to prefabricate vascularized nerve constructs which could overcome the limitations of grafts. In this review article, we focus on the role of vascularization in nerve regeneration, discussing various approaches to generate vascularized nerve constructs and the contribution of tissue engineering and mathematical modeling to aid in developing vascularized engineered nerve constructs, illustrating these aspects with examples from our research experience. Anat Rec, 301:1657–1667, 2018. © 2018 The Authors. The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.
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Affiliation(s)
- Papon Muangsanit
- Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, University College London, London, UK.,UCL Centre for Nerve Engineering, University College London, London, UK.,Department of Pharmacology, UCL School of Pharmacy, University College London, London, UK
| | - Rebecca J Shipley
- UCL Centre for Nerve Engineering, University College London, London, UK.,UCL Mechanical Engineering, University College London, London, UK
| | - James B Phillips
- Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, University College London, London, UK.,UCL Centre for Nerve Engineering, University College London, London, UK.,Department of Pharmacology, UCL School of Pharmacy, University College London, London, UK
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16
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O'Rourke C, Day AGE, Murray-Dunning C, Thanabalasundaram L, Cowan J, Stevanato L, Grace N, Cameron G, Drake RAL, Sinden J, Phillips JB. An allogeneic 'off the shelf' therapeutic strategy for peripheral nerve tissue engineering using clinical grade human neural stem cells. Sci Rep 2018; 8:2951. [PMID: 29440680 PMCID: PMC5811594 DOI: 10.1038/s41598-018-20927-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 01/23/2018] [Indexed: 02/07/2023] Open
Abstract
Artificial tissues constructed from therapeutic cells offer a promising approach for improving the treatment of severe peripheral nerve injuries. In this study the effectiveness of using CTX0E03, a conditionally immortalised human neural stem cell line, as a source of allogeneic cells for constructing living artificial nerve repair tissue was tested. CTX0E03 cells were differentiated then combined with collagen to form engineered neural tissue (EngNT-CTX), stable aligned sheets of cellular hydrogel. EngNT-CTX sheets were delivered within collagen tubes to repair a 12 mm sciatic nerve injury model in athymic nude rats. Autologous nerve grafts (autografts) and empty tubes were used for comparison. After 8 weeks functional repair was assessed using electrophysiology. Further, detailed histological and electron microscopic analysis of the repaired nerves was performed. Results indicated that EngNT-CTX supported growth of neurites and vasculature through the injury site and facilitated reinnervation of the target muscle. These findings indicate for the first time that a clinically validated allogeneic neural stem cell line can be used to construct EngNT. This provides a potential 'off the shelf' tissue engineering solution for the treatment of nerve injury, overcoming the limitations associated with nerve autografts or the reliance on autologous cells for populating repair constructs.
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Affiliation(s)
- C O'Rourke
- Department of Biomaterials & Tissue Engineering, UCL Eastman Dental Institute, University College London, London, UK
- UCL Centre for Nerve Engineering, London, UK
| | - A G E Day
- Department of Biomaterials & Tissue Engineering, UCL Eastman Dental Institute, University College London, London, UK
- UCL Centre for Nerve Engineering, London, UK
| | - C Murray-Dunning
- Department of Biomaterials & Tissue Engineering, UCL Eastman Dental Institute, University College London, London, UK
| | - L Thanabalasundaram
- UCL Centre for Nerve Engineering, London, UK
- ReNeuron, Pencoed, Bridgend, Wales, UK
| | - J Cowan
- Royal National Orthopaedic Hospital, Stanmore, UK
| | | | - N Grace
- Sartorius Stedim Biotech, Royston, UK
| | - G Cameron
- Sartorius Stedim Biotech, Royston, UK
| | | | - J Sinden
- UCL Centre for Nerve Engineering, London, UK
- ReNeuron, Pencoed, Bridgend, Wales, UK
| | - J B Phillips
- Department of Biomaterials & Tissue Engineering, UCL Eastman Dental Institute, University College London, London, UK.
- UCL Centre for Nerve Engineering, London, UK.
- Department of Pharmacology, UCL School of Pharmacy, University College London, London, UK.
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17
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Mukhey D, Phillips JB, Daniels JT, Kureshi AK. Controlling human corneal stromal stem cell contraction to mediate rapid cell and matrix organization of real architecture for 3-dimensional tissue equivalents. Acta Biomater 2018; 67:229-237. [PMID: 29208552 DOI: 10.1016/j.actbio.2017.11.047] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 11/07/2017] [Accepted: 11/28/2017] [Indexed: 12/13/2022]
Abstract
The architecture of the human corneal stroma consists of a highly organized extracellular matrix (ECM) interspersed with keratocytes. Their progenitor cells; corneal stromal stem cells (CSSC) are located at the periphery, in the limbal stroma. A highly organized corneal ECM is critical for effective transmission of light but this structure may be compromised during injury or disease, resulting in loss of vision. Re-creating normal organization in engineered tissue equivalents for transplantation often involves lengthy culture times that are inappropriate for clinical use or utilisation of synthetic substrates that bring complications such as corneal melting. CSSC have great therapeutic potential owing to their ability to reorganize a disorganized matrix, restoring transparency in scarred corneas. We examined CSSC contractile behavior to assess whether this property could be exploited to rapidly generate cell and ECM organization in Real Architecture For 3D Tissues (RAFT) tissue equivalents (TE) for transplantation. Free-floating collagen gels were characterized to assess contractile behavior of CSSC and establish optimum cell density and culture times. To mediate cell and collagen organization, tethered collagen gels seeded with CSSC were cultured and subsequently stabilized with the RAFT process. We demonstrated rapid creation of biomimetic RAFT TE with tunable structural properties. These displayed three distinct regions of varying degrees of cellular and collagen organization. Interestingly, increased organization coincided with a dramatic loss of PAX6 expression in CSSC, indicating rapid differentiation into keratocytes. The organized RAFT TE system could be a useful bioengineering tool to rapidly create an organized ECM while simultaneously controlling cell phenotype. STATEMENT OF SIGNIFICANCE For the first time, we have demonstrated that human CSSC exhibit the phenomenon of cellular self-alignment in tethered collagen gels. We found this mediated rapid co-alignment of collagen fibrils and thus subsequently exploited this property in vitro to improve the architecture of engineered RAFT tissue equivalents of the corneal stroma. Existing techniques are extremely lengthy and carry significant risk and cost for GMP manufacture. This rapid and tunable technique takes just 8 h of culture and is therefore ideal for clinical manufacture, creating biomimetic tissue equivalents with both cellular and ECM organization. Thus, cellular self-alignment can be a useful bioengineering tool for the development of organized tissue equivalents in a variety of applications.
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18
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Antman-Passig M, Levy S, Gartenberg C, Schori H, Shefi O. Mechanically Oriented 3D Collagen Hydrogel for Directing Neurite Growth. Tissue Eng Part A 2017; 23:403-414. [PMID: 28437179 DOI: 10.1089/ten.tea.2016.0185] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Recent studies in the field of neuro-tissue engineering have demonstrated the promising effects of aligned contact guidance cue to scaffolds of enhancement and direction of neuronal growth. In vivo, neurons grow and develop neurites in a complex three-dimensional (3D) extracellular matrix (ECM) surrounding. Studies have utilized hydrogel scaffolds derived from ECM molecules to better simulate natural growth. While many efforts have been made to control neuronal growth on 2D surfaces, the development of 3D scaffolds with an elaborate oriented topography to direct neuronal growth still remains a challenge. In this study, we designed a method for growing neurons in an aligned and oriented 3D collagen hydrogel. We aligned collagen fibers by inducing controlled uniaxial strain on gels. To examine the collagen hydrogel as a suitable scaffold for neuronal growth, we evaluated the physical properties of the hydrogel and measured collagen fiber properties. By combining the neuronal culture in 3D collagen hydrogels with strain-induced alignment, we were able to direct neuronal growth in the direction of the aligned collagen matrix. Quantitative evaluation of neurite extension and directionality within aligned gels was performed. The analysis showed neurite growth aligned with collagen matrix orientation, while maintaining the advantageous 3D growth.
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Affiliation(s)
- Merav Antman-Passig
- Faculty of Engineering, Bar Ilan Institute of Nanotechnologies and Advanced Materials, Bar Ilan University , Ramat Gan, Israel
| | - Shahar Levy
- Faculty of Engineering, Bar Ilan Institute of Nanotechnologies and Advanced Materials, Bar Ilan University , Ramat Gan, Israel
| | - Chaim Gartenberg
- Faculty of Engineering, Bar Ilan Institute of Nanotechnologies and Advanced Materials, Bar Ilan University , Ramat Gan, Israel
| | - Hadas Schori
- Faculty of Engineering, Bar Ilan Institute of Nanotechnologies and Advanced Materials, Bar Ilan University , Ramat Gan, Israel
| | - Orit Shefi
- Faculty of Engineering, Bar Ilan Institute of Nanotechnologies and Advanced Materials, Bar Ilan University , Ramat Gan, Israel
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19
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O'Rourke C, Lee-Reeves C, Drake RA, Cameron GW, Loughlin AJ, Phillips JB. Adapting tissue-engineered in vitro CNS models for high-throughput study of neurodegeneration. J Tissue Eng 2017; 8:2041731417697920. [PMID: 28507726 PMCID: PMC5415290 DOI: 10.1177/2041731417697920] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 02/14/2017] [Indexed: 11/21/2022] Open
Abstract
Neurodegenerative conditions remain difficult to treat, with the continuing failure to see therapeutic research successfully advance to clinical trials. One of the obstacles that must be overcome is to develop enhanced models of disease. Tissue engineering techniques enable us to create organised artificial central nervous system tissue that has the potential to improve the drug development process. This study presents a replicable model of neurodegenerative pathology through the use of engineered neural tissue co-cultures that can incorporate cells from various sources and allow degeneration and protection of neurons to be observed easily and measured, following exposure to neurotoxic compounds – okadaic acid and 1-methyl-4-phenylpyridinium. Furthermore, the technology has been miniaturised through development of a mould with 6 mm length that recreates the advantageous features of engineered neural tissue co-cultures at a scale suitable for commercial research and development. Integration of human-derived induced pluripotent stem cells aids more accurate modelling of human diseases, creating new possibilities for engineered neural tissue co-cultures and their use in drug screening.
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Affiliation(s)
- Caitriona O'Rourke
- Department of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, University College London, London, UK.,Department of Life, Health and Chemical Sciences, The Open University, Milton Keynes, UK
| | - Charlotte Lee-Reeves
- Department of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, University College London, London, UK
| | | | | | - A Jane Loughlin
- Department of Life, Health and Chemical Sciences, The Open University, Milton Keynes, UK
| | - James B Phillips
- Department of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, University College London, London, UK
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20
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Anisotropically organized three-dimensional culture platform for reconstruction of a hippocampal neural network. Nat Commun 2017; 8:14346. [PMID: 28146148 PMCID: PMC5296669 DOI: 10.1038/ncomms14346] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 12/19/2016] [Indexed: 01/06/2023] Open
Abstract
In native tissues, cellular and acellular components are anisotropically organized and often aligned in specific directions, providing structural and mechanical properties for actuating biological functions. Thus, engineering alignment not only allows for emulation of native tissue structures but might also enable implementation of specific functionalities. However, achieving desired alignment is challenging, especially in three-dimensional constructs. By exploiting the elastomeric property of polydimethylsiloxane and fibrillogenesis kinetics of collagen, here we introduce a simple yet effective method to assemble and align fibrous structures in a multi-modular three-dimensional conglomerate. Applying this method, we have reconstructed the CA3–CA1 hippocampal neural circuit three-dimensionally in a monolithic gel, in which CA3 neurons extend parallel axons to and synapse with CA1 neurons. Furthermore, we show that alignment of the fibrous scaffold facilitates the establishment of functional connectivity. This method can be applied for reconstructing other neural circuits or tissue units where anisotropic organization in a multi-modular structure is desired. Alignment or anisotropic organisation within and between cells enables biological function but is challenging to engineer. Here, the authors align collagen fibres in a pre-strained polydimethylsiloxane mould to generate a 3D scaffold that guides hippocampal neuron axon growth to form CA3–CA1 neural circuits.
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21
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Sanen K, Martens W, Georgiou M, Ameloot M, Lambrichts I, Phillips J. Engineered neural tissue with Schwann cell differentiated human dental pulp stem cells: potential for peripheral nerve repair? J Tissue Eng Regen Med 2017; 11:3362-3372. [PMID: 28052540 DOI: 10.1002/term.2249] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 06/14/2016] [Accepted: 07/03/2016] [Indexed: 12/18/2022]
Abstract
Despite the spontaneous regenerative capacity of the peripheral nervous system, large gap peripheral nerve injuries (PNIs) require bridging strategies. The limitations and suboptimal results obtained with autografts or hollow nerve conduits in the clinic urge the need for alternative treatments. Recently, we have described promising neuroregenerative capacities of Schwann cells derived from differentiated human dental pulp stem cells (d-hDPSCs) in vitro. Here, we extended the in vitro assays to show the pro-angiogenic effects of d-hDPSCs, such as enhanced endothelial cell proliferation, migration and differentiation. In addition, for the first time we evaluated the performance of d-hDPSCs in an in vivo rat model of PNI. Eight weeks after transplantation of NeuraWrap™ conduits filled with engineered neural tissue (EngNT) containing aligned d-hDPSCs in 15-mm rat sciatic nerve defects, immunohistochemistry and ultrastructural analysis revealed ingrowing neurites, myelinated nerve fibres and blood vessels along the construct. Although further research is required to optimize the delivery of this EngNT, our findings suggest that d-hDPSCs are able to exert a positive effect in the regeneration of nerve tissue in vivo. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- Kathleen Sanen
- Biophysics Group, Biomedical Research Institute, Hasselt University, Agoralaan Building C, 3590, Diepenbeek, Belgium
| | - Wendy Martens
- Morphology Group, Biomedical Research Institute, Hasselt University, Agoralaan Building C, 3590, Diepenbeek, Belgium
| | - Melanie Georgiou
- Advanced Centre for Biochemical Engineering, University College London, Bernard Katz Building, Gordon Street, London, WC1H 0AH, UK
| | - Marcel Ameloot
- Biophysics Group, Biomedical Research Institute, Hasselt University, Agoralaan Building C, 3590, Diepenbeek, Belgium
| | - Ivo Lambrichts
- Morphology Group, Biomedical Research Institute, Hasselt University, Agoralaan Building C, 3590, Diepenbeek, Belgium
| | - James Phillips
- Biomaterials & Tissue Engineering, UCL Eastman Dental Institute, University College London, 256 Gray's Inn Road, London, WC1X 8LD, UK
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