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McKinley JP, O'Connell GD. Review of state-of-the-art micro and macro-bioreactors for the intervertebral disc. J Biomech 2024; 165:111964. [PMID: 38412621 DOI: 10.1016/j.jbiomech.2024.111964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 01/02/2024] [Accepted: 01/23/2024] [Indexed: 02/29/2024]
Abstract
Lower back pain continues to be a global epidemic, limiting quality of life and ability to work, due in large part to symptomatic disc degeneration. Development of more effective and less invasive biological strategies are needed to treat disc degeneration. In vitro models such as macro- or micro-bioreactors or mechanically active organ-chips hold great promise in reducing the need for animal studies that may have limited clinical translatability, due to harsher and more complex mechanical loading environments in human discs than in most animal models. This review highlights the complex loading conditions of the disc in situ, evaluates state-of-the-art designs for applying such complex loads across multiple length scales, from macro-bioreactors that load whole discs to organ-chips that aim to replicate cellular or engineered tissue loading. Emphasis was placed on the rapidly evolving more customizable organ-chips, given their greater potential for studying the progression and treatment of symptomatic disc degeneration. Lastly, this review identifies new trends and challenges for using organ-chips to assess therapeutic strategies.
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Affiliation(s)
- Jonathan P McKinley
- Berkeley BioMechanics Laboratory, Department of Mechanical Engineering, University of California, Berkeley 94720, CA, USA.
| | - Grace D O'Connell
- Berkeley BioMechanics Laboratory, Department of Mechanical Engineering, University of California, Berkeley 94720, CA, USA.
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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] [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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