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Tran KA, DeOre BJ, Ikejiani D, Means K, Paone LS, De Marchi L, Suprewicz Ł, Koziol K, Bouyer J, Byfield FJ, Jin Y, Georges P, Fischer I, Janmey PA, Galie PA. Matching mechanical heterogeneity of the native spinal cord augments axon infiltration in 3D-printed scaffolds. Biomaterials 2023; 295:122061. [PMID: 36842339 PMCID: PMC10292106 DOI: 10.1016/j.biomaterials.2023.122061] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 02/09/2023] [Accepted: 02/15/2023] [Indexed: 02/18/2023]
Abstract
Scaffolds delivered to injured spinal cords to stimulate axon connectivity often match the anisotropy of native tissue using guidance cues along the rostral-caudal axis, but current approaches do not mimic the heterogeneity of host tissue mechanics. Although white and gray matter have different mechanical properties, it remains unclear whether tissue mechanics also vary along the length of the cord. Mechanical testing performed in this study indicates that bulk spinal cord mechanics do differ along anatomical level and that these differences are caused by variations in the ratio of white and gray matter. These results suggest that scaffolds recreating the heterogeneity of spinal cord tissue mechanics must account for the disparity between gray and white matter. Digital light processing (DLP) provides a means to mimic spinal cord topology, but has previously been limited to printing homogeneous mechanical properties. We describe a means to modify DLP to print scaffolds that mimic spinal cord mechanical heterogeneity caused by variation in the ratio of white and gray matter, which improves axon infiltration compared to controls exhibiting homogeneous mechanical properties. These results demonstrate that scaffolds matching the mechanical heterogeneity of white and gray matter improve the effectiveness of biomaterials transplanted within the injured spinal cord.
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Affiliation(s)
- Kiet A Tran
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ, USA
| | - Brandon J DeOre
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ, USA
| | - David Ikejiani
- Department of Bioengineering, Rice University, Houston, TX, USA
| | - Kristen Means
- Department of Bioengineering, Rice University, Houston, TX, USA
| | - Louis S Paone
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ, USA
| | - Laura De Marchi
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ, USA
| | - Łukasz Suprewicz
- Department of Medical Microbiology and Nanobiomedical Engineering, Medical University of Bialystok, Bialystok, Poland
| | - Katarina Koziol
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ, USA
| | - Julien Bouyer
- Department of Neurobiology and Anatomy, Drexel College of Medicine, Philadelphia, PA, USA
| | - Fitzroy J Byfield
- Department of Physiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Ying Jin
- Department of Neurobiology and Anatomy, Drexel College of Medicine, Philadelphia, PA, USA
| | - Penelope Georges
- Council on Science and Technology, Princeton University, Princeton, NJ, USA
| | - Itzhak Fischer
- Department of Neurobiology and Anatomy, Drexel College of Medicine, Philadelphia, PA, USA
| | - Paul A Janmey
- Department of Physiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Peter A Galie
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ, USA.
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How do cells stiffen? Biochem J 2022; 479:1825-1842. [PMID: 36094371 DOI: 10.1042/bcj20210806] [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: 05/11/2022] [Revised: 08/21/2022] [Accepted: 08/24/2022] [Indexed: 11/17/2022]
Abstract
Cell stiffness is an important characteristic of cells and their response to external stimuli. In this review, we survey methods used to measure cell stiffness, summarize stimuli that alter cell stiffness, and discuss signaling pathways and mechanisms that control cell stiffness. Several pathological states are characterized by changes in cell stiffness, suggesting this property can serve as a potential diagnostic marker or therapeutic target. Therefore, we consider the effect of cell stiffness on signaling and growth processes required for homeostasis and dysfunction in healthy and pathological states. Specifically, the composition and structure of the cell membrane and cytoskeleton are major determinants of cell stiffness, and studies have identified signaling pathways that affect cytoskeletal dynamics both directly and by altered gene expression. We present the results of studies interrogating the effects of biophysical and biochemical stimuli on the cytoskeleton and other cellular components and how these factors determine the stiffness of both individual cells and multicellular structures. Overall, these studies represent an intersection of the fields of polymer physics, protein biochemistry, and mechanics, and identify specific mechanisms involved in mediating cell stiffness that can serve as therapeutic targets.
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