201
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Colmenárez-Raga AC, Díaz I, Pernia M, Pérez-González D, Delgado-García JM, Carro J, Plaza I, Merchán MA. Reversible Functional Changes Evoked by Anodal Epidural Direct Current Electrical Stimulation of the Rat Auditory Cortex. Front Neurosci 2019; 13:356. [PMID: 31031588 PMCID: PMC6473088 DOI: 10.3389/fnins.2019.00356] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 03/28/2019] [Indexed: 12/26/2022] Open
Abstract
Rat auditory cortex was subjected to 0.1 mA anodal direct current in seven 10-min sessions on alternate days. Based on the well-known auditory cortex control of olivocochlear regulation through corticofugal projections, auditory brainstem responses (ABRs) were recorded as an indirect test of the effectiveness and reversibility of the multisession protocol of epidural stimulation. Increases of 20-30 dB ABR auditory thresholds shown after epidural stimulation reverted back to control levels 10 min after a single session. However, increases in thresholds revert 4 days after multisession stimulation. Less changes in wave amplitudes and threshold shifts were shown in ABR recorded contralaterally to the electrically stimulated side of the brain. To assess tissue effects of epidural electric stimulation on the brain cortex, well characterized functional anatomical markers of glial cells (GFAP/astrocytes and Iba1/microglial cells) and neurons (c-Fos) were analyzed in alternate serial sections by quantitative immunocytochemistry. Restricted astroglial and microglial reactivity was observed within the cytoarchitectural limits of the auditory cortex. However, interstitial GFAP overstaining was also observed in the ventricular surface and around blood vessels, thus supporting a potential global electrolytic stimulation of the brain. These results correlate with extensive changes in the distribution of c-Fos immunoreactive neurons among layers along sensory cortices after multisession stimulation. Quantitative immunocytochemical analysis supported this idea by showing a significant increase in the number of positive neurons in supragranular layers and a decrease in layer 6 with no quantitative changes detected in layer 5. Our data indicate that epidural stimulation of the auditory cortex induces a reversible decrease in hearing sensitivity due to local, restricted epidural stimulation. A global plastic response of the sensory cortices, also reported here, may be related to electrolytic effects of electric currents.
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Affiliation(s)
| | - Iván Díaz
- Instituto de Neurociencias de Castilla y León, University of Salamanca, Salamanca, Spain
| | - Marianny Pernia
- Instituto de Neurociencias de Castilla y León, University of Salamanca, Salamanca, Spain
| | - David Pérez-González
- Instituto de Neurociencias de Castilla y León, University of Salamanca, Salamanca, Spain
| | | | - Juan Carro
- Instituto de Neurociencias de Castilla y León, University of Salamanca, Salamanca, Spain
| | - Ignacio Plaza
- Instituto de Neurociencias de Castilla y León, University of Salamanca, Salamanca, Spain
| | - Miguel A. Merchán
- Instituto de Neurociencias de Castilla y León, University of Salamanca, Salamanca, Spain
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202
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Finan JD. Biomechanical simulation of traumatic brain injury in the rat. Clin Biomech (Bristol, Avon) 2019; 64:114-121. [PMID: 29449041 PMCID: PMC6068009 DOI: 10.1016/j.clinbiomech.2018.01.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 12/08/2017] [Accepted: 01/18/2018] [Indexed: 02/07/2023]
Abstract
BACKGROUND Traumatic brain injury poses an enormous clinical challenge. Rats are the animals most widely used in pre-clinical experiments. Biomechanical simulations of these experiments predict the distribution of mechanical stress and strain across key tissues. It is in theory possible to dramatically increase our understanding of traumatic brain injury pathophysiology by correlating stress and strain with histological and functional injury outcomes. This review summarizes the state of the art in biomechanical simulation of traumatic brain injury in the rat. It also places this body of knowledge in the context of the wider effort to understand traumatic brain injury in rats and in humans. METHODS Peer-reviewed research articles on biomechanical simulation of traumatic brain injury in the rat were reviewed and summarized. FINDINGS When mathematical models of traumatic brain injury in the rat first emerged, they relied on scant data regarding biomechanical properties. The data on relevant biomechanical properties has increased recently. However, experimental models of traumatic brain injury in the rat have also become less homogeneous. New and modified models have emerged that are biomechanically distinct from traditional models. INTERPRETATION Important progress in mathematical modeling and measurement of biomechanical properties has led to credible, predictive simulations of traditional, experimental models of traumatic brain injury in the rat, such as controlled cortical impact. However, recent trends such as the increasing popularity of closed head models and blast models create new biomechanical challenges. Investigators studying rat brain biomechanics must continue to innovate to keep pace with these developments.
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203
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Dagro AM, Ramesh KT. Nonlinear contact mechanics for the indentation of hyperelastic cylindrical bodies. ACTA ACUST UNITED AC 2019. [DOI: 10.1007/s42558-019-0006-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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204
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Wilems T, Vardhan S, Wu S, Sakiyama-Elbert S. The influence of microenvironment and extracellular matrix molecules in driving neural stem cell fate within biomaterials. Brain Res Bull 2019; 148:25-33. [PMID: 30898579 DOI: 10.1016/j.brainresbull.2019.03.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 03/07/2019] [Accepted: 03/12/2019] [Indexed: 12/17/2022]
Abstract
Transplantation of stem cells is a promising potential therapy for central nervous system disease and injury. The capacity for self-renewal, proliferation of progenitor cells, and multi-lineage potential underscores the need for controlling stem cell fate. Furthermore, transplantation within a hostile environment can lead to significant cell death and limited therapeutic potential. Tissue-engineered materials have been developed to both regulate stem cell fate, increase transplanted cell viability, and improve therapeutic outcomes. Traditionally, regulation of stem cell differentiation has been driven through soluble signals, such as growth factors. While these signals are important, insoluble factors from the local microenvironment or extracellular matrix (ECM) molecules also contribute to stem cell activity and fate. Understanding the microenvironment factors that influence stem cell fate, such as mechanical properties, topography, and presentation of specific ECM ligands, is necessary for designing improved biomaterials. Here we review some of the microenvironment factors that regulate stem cell fate and how they can be incorporated into biomaterials as part of potential CNS therapies.
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Affiliation(s)
- Thomas Wilems
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, 78712, USA
| | - Sangamithra Vardhan
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, 78712, USA
| | - Siliang Wu
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, 78712, USA
| | - Shelly Sakiyama-Elbert
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, 78712, USA.
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205
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Mouse mast cell protease 4 suppresses scar formation after traumatic spinal cord injury. Sci Rep 2019; 9:3715. [PMID: 30842526 PMCID: PMC6403346 DOI: 10.1038/s41598-019-39551-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 01/14/2019] [Indexed: 12/15/2022] Open
Abstract
Spinal cord injury (SCI) triggers the formation of a glial and fibrotic scar, which creates a major barrier for neuroregenerative processes. Previous findings indicate that mast cells (MCs) protect the spinal cord after mechanical damage by suppressing detrimental inflammatory processes via mouse mast cell protease 4 (mMCP4), a MC-specific chymase. In addition to these immunomodulatory properties, mMCP4 also plays an important role in tissue remodeling and extracellular matrix degradation. Therefore, we have investigated the effects of mMCP4 on the scarring response after SCI. We demonstrate that the decrease in locomotor performance in mMCP4-/- mice is correlated with excessive scar formation at the lesion. The expression of axon-growth inhibitory chondroitin sulfate proteoglycans was dramatically increased in the perilesional area in mMCP4-/- mice compared to wild type mice. Moreover, the fibronectin-, laminin-, and collagen IV-positive scar was significantly enlarged in mMCP4-/- mice at the lesion center. A degradation assay revealed that mMCP4 directly cleaves collagen IV in vitro. On the gene expression level, neurocan and GFAP were significantly higher in the mMCP4-/- group at day 2 and day 28 after injury respectively. In contrast, the expression of fibronectin and collagen IV was reduced in mMCP4-/- mice compared to WT mice at day 7 after SCI. In conclusion, our data show that mMCP4 modulates scar development after SCI by altering the gene and protein expression patterns of key scar factors in vivo. Therefore, we suggest a new mechanism via which endogenous mMCP4 can improve recovery after SCI.
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206
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Tsai E, Casaccia P. Mechano-modulation of nuclear events regulating oligodendrocyte progenitor gene expression. Glia 2019; 67:1229-1239. [PMID: 30734358 DOI: 10.1002/glia.23595] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 01/03/2019] [Accepted: 01/14/2019] [Indexed: 12/20/2022]
Abstract
Oligodendrocytes differentiate from oligodendrocyte progenitor cells (OPCs) in response to distinct extracellular signals. This process requires changes in gene expression resulting from the interplay between transcription factors and epigenetic modulators. Extracellular signals include chemical and physical stimuli. This review focuses on the signaling mechanisms activated in oligodendrocyte progenitors in response to mechanical forces. Of particular interest is a better understanding on how these forces are transduced into the OPC nuclei and subsequently reshape their epigenetic landscape. Here we will introduce the concept of epigenetic regulation of gene expression, first in general and then focusing on the oligodendrocyte lineage. We will then review the current literature on mechano-transduction in distinct cell types, followed by pathways identified in myelinating oligodendrocytes and their progenitors. Overall, the reader will be provided with a comprehensive review of the signaling pathways which allow oligodendrocyte progenitors to "sense" physical forces and transduce them into patterns of gene expression.
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Affiliation(s)
- Eric Tsai
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York.,Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Patrizia Casaccia
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York.,Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, New York.,Department of Biology and Biochemistry, Neuroscience Initiative at the Advanced Science Research Center of the Graduate Center of The City University of New York, New York
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207
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Myelinated axons and functional blood vessels populate mechanically compliant rGO foams in chronic cervical hemisected rats. Biomaterials 2019; 192:461-474. [DOI: 10.1016/j.biomaterials.2018.11.024] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 11/06/2018] [Accepted: 11/13/2018] [Indexed: 11/18/2022]
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208
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Acute and chronic demyelinated CNS lesions exhibit opposite elastic properties. Sci Rep 2019; 9:999. [PMID: 30700777 PMCID: PMC6354022 DOI: 10.1038/s41598-018-37745-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 12/07/2018] [Indexed: 01/07/2023] Open
Abstract
Increased deposition of extracellular matrix (ECM) is a known inhibitor of axonal regrowth and remyelination. Recent in vitro studies have demonstrated that oligodendrocyte differentiation is impacted by the physical properties of the ECM. However, characterization of the mechanical properties of the healthy and injured CNS myelin is challenging, and has largely relied on non-invasive, low-resolution methods. To address this, we have employed atomic force microscopy to perform micro-indentation measurements of demyelinated tissue at cellular scale. Analysis of mouse and human demyelinated brains indicate that acute demyelination results in decreased tissue stiffness that recovers with remyelination; while chronic demyelination is characterized by increased tissue stiffness, which correlates with augmented ECM deposition. Thus, changes in the mechanical properties of the acutely (softer) or chronically (stiffer) demyelinated brain might contribute to differences in their regenerative capacity. Our findings are relevant to the optimization of cell-based therapies aimed at promoting CNS regeneration and remyelination.
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209
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Thompson AJ, Pillai EK, Dimov IB, Foster SK, Holt CE, Franze K. Rapid changes in tissue mechanics regulate cell behaviour in the developing embryonic brain. eLife 2019; 8:e39356. [PMID: 30642430 PMCID: PMC6333438 DOI: 10.7554/elife.39356] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 12/10/2018] [Indexed: 12/17/2022] Open
Abstract
Tissue mechanics is important for development; however, the spatio-temporal dynamics of in vivo tissue stiffness is still poorly understood. We here developed tiv-AFM, combining time-lapse in vivo atomic force microscopy with upright fluorescence imaging of embryonic tissue, to show that during development local tissue stiffness changes significantly within tens of minutes. Within this time frame, a stiffness gradient arose in the developing Xenopus brain, and retinal ganglion cell axons turned to follow this gradient. Changes in local tissue stiffness were largely governed by cell proliferation, as perturbation of mitosis diminished both the stiffness gradient and the caudal turn of axons found in control brains. Hence, we identified a close relationship between the dynamics of tissue mechanics and developmental processes, underpinning the importance of time-resolved stiffness measurements.
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Affiliation(s)
- Amelia J Thompson
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUnited Kingdom
| | - Eva K Pillai
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUnited Kingdom
| | - Ivan B Dimov
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUnited Kingdom
| | - Sarah K Foster
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUnited Kingdom
| | - Christine E Holt
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUnited Kingdom
| | - Kristian Franze
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUnited Kingdom
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210
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Cell-matrix tension contributes to hypoxia in astrocyte-seeded viscoelastic hydrogels composed of collagen and hyaluronan. Exp Cell Res 2019; 376:49-57. [PMID: 30658092 DOI: 10.1016/j.yexcr.2019.01.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 01/08/2019] [Accepted: 01/14/2019] [Indexed: 11/22/2022]
Abstract
Astrocyte activation is crucial for wound contraction and glial scar formation following central nervous system injury, but the mechanism by which activation leads to astrocyte contractility and matrix reorganization in the central nervous system (CNS) is unknown. Current means to measure cell traction forces within three-dimensional scaffolds are limited to analyzing individual or small groups of cells, within extracellular matrices, whereas gap junctions and other cell-cell adhesions connect astrocytes to form a functional syncytium within the glial scar. Here, we measure the viscoelastic properties of cell-seeded hydrogels to yield insight into the collective contractility of astrocytes as they exert tension on the surrounding matrix and change its bulk mechanical properties. Our results indicate that incorporation of the CNS matrix component hyaluronan into a collagen hydrogel increases expression of the intermediate filament protein GFAP and results in a higher shear storage modulus of the cell/matrix composite, establishing the correlation between astrocyte activation and increased cell contractility. The effects of thrombin and blebbistatin, known mediators of actomyosin-mediated contraction, verify that cell-matrix tension dictates the hydrogel mechanical properties. Viability assays indicate that increased cell traction exacerbates cell death at the center of the scaffold, and message level analysis reveals that cells in the hyaluronan-containing matrix have a ~ 3-fold increase in HIF-1α gene expression. Overall, these findings suggest that astrocyte activation not only increases cell traction, but may also contribute to hypoxia near sites of central nervous system injury.
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211
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Barua S, Kim JY, Lee JE. Role of Agmatine on Neuroglia in Central Nervous System Injury. BRAIN & NEUROREHABILITATION 2019. [DOI: 10.12786/bn.2019.12.e2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Sumit Barua
- Department of Anatomy, Yonsei University College of Medicine, Seoul, Korea
| | - Jong Youl Kim
- Department of Anatomy, Yonsei University College of Medicine, Seoul, Korea
| | - Jong Eun Lee
- Department of Anatomy, Yonsei University College of Medicine, Seoul, Korea
- Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
- Brain Research Institute, Yonsei University College of Medicine, Seoul, Korea
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212
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Jiao J, Huang J, Zhang Z. Hydrogels based on chitosan in tissue regeneration: How do they work? A mini review. J Appl Polym Sci 2018. [DOI: 10.1002/app.47235] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Jiao Jiao
- Neuropsychiatric Institute; Medical School of Southeast University; Nanjing Jiangsu 210009 China
- Department of Neurology; Affiliated ZhongDa Hospital; Nanjing Jiangsu 210009 China
| | - Jinjian Huang
- Lab for Trauma and Surgical Infections, Department of Surgery; Jinling Hospital; Nanjing Jiangsu 210002 China
| | - Zhijun Zhang
- Neuropsychiatric Institute; Medical School of Southeast University; Nanjing Jiangsu 210009 China
- Department of Neurology; Affiliated ZhongDa Hospital; Nanjing Jiangsu 210009 China
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213
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Estrada V, Krebbers J, Voss C, Brazda N, Blazyca H, Illgen J, Seide K, Jürgens C, Müller J, Martini R, Trieu HK, Müller HW. Low-pressure micro-mechanical re-adaptation device sustainably and effectively improves locomotor recovery from complete spinal cord injury. Commun Biol 2018; 1:205. [PMID: 30511019 PMCID: PMC6255786 DOI: 10.1038/s42003-018-0210-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 10/31/2018] [Indexed: 12/16/2022] Open
Abstract
Traumatic spinal cord injuries result in impairment or even complete loss of motor, sensory and autonomic functions. Recovery after complete spinal cord injury is very limited even in animal models receiving elaborate combinatorial treatments. Recently, we described an implantable microsystem (microconnector) for low-pressure re-adaption of severed spinal stumps in rat. Here we investigate the long-term structural and functional outcome following microconnector implantation after complete spinal cord transection. Re-adaptation of spinal stumps supports formation of a tissue bridge, glial and vascular cell invasion, motor axon regeneration and myelination, resulting in partial recovery of motor-evoked potentials and a thus far unmet improvement of locomotor behaviour. The recovery lasts for at least 5 months. Despite a late partial decline, motor recovery remains significantly superior to controls. Our findings demonstrate that microsystem technology can foster long-lasting functional improvement after complete spinal injury, providing a new and effective tool for combinatorial therapies.
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Affiliation(s)
- Veronica Estrada
- 1Molecular Neurobiology Laboratory, Department of Neurology, Heinrich-Heine-University Medical Centre Düsseldorf, Moorenstr. 5, 40225 Düsseldorf, Germany
| | - Julia Krebbers
- 1Molecular Neurobiology Laboratory, Department of Neurology, Heinrich-Heine-University Medical Centre Düsseldorf, Moorenstr. 5, 40225 Düsseldorf, Germany
| | - Christian Voss
- 2Institute of Microsystems Technology, Hamburg University of Technology, Eißendorfer Str. 42, 21073 Hamburg, Germany.,BG Trauma Centre Hamburg, Bergedorfer Str. 10, 21033 Hamburg, Germany
| | - Nicole Brazda
- 1Molecular Neurobiology Laboratory, Department of Neurology, Heinrich-Heine-University Medical Centre Düsseldorf, Moorenstr. 5, 40225 Düsseldorf, Germany
| | - Heinrich Blazyca
- 4Developmental Neurobiology, Department of Neurology, University Hospital Würzburg, Josef-Schneider-Str. 11, 97080 Würzburg, Germany
| | - Jennifer Illgen
- 1Molecular Neurobiology Laboratory, Department of Neurology, Heinrich-Heine-University Medical Centre Düsseldorf, Moorenstr. 5, 40225 Düsseldorf, Germany
| | - Klaus Seide
- BG Trauma Centre Hamburg, Bergedorfer Str. 10, 21033 Hamburg, Germany
| | - Christian Jürgens
- BG Trauma Centre Hamburg, Bergedorfer Str. 10, 21033 Hamburg, Germany
| | - Jörg Müller
- 2Institute of Microsystems Technology, Hamburg University of Technology, Eißendorfer Str. 42, 21073 Hamburg, Germany
| | - Rudolf Martini
- 4Developmental Neurobiology, Department of Neurology, University Hospital Würzburg, Josef-Schneider-Str. 11, 97080 Würzburg, Germany
| | - Hoc Khiem Trieu
- 2Institute of Microsystems Technology, Hamburg University of Technology, Eißendorfer Str. 42, 21073 Hamburg, Germany
| | - Hans Werner Müller
- 1Molecular Neurobiology Laboratory, Department of Neurology, Heinrich-Heine-University Medical Centre Düsseldorf, Moorenstr. 5, 40225 Düsseldorf, Germany.,CNR (Center for Neuronal Regeneration), Merowinger Platz 1a, 40225 Düsseldorf, Germany.,6Biomedical Research Center, Heinrich-Heine-University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
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214
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Bertalan G, Guo J, Tzschätzsch H, Klein C, Barnhill E, Sack I, Braun J. Fast tomoelastography of the mouse brain by multifrequency single‐shot MR elastography. Magn Reson Med 2018; 81:2676-2687. [DOI: 10.1002/mrm.27586] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 10/04/2018] [Accepted: 10/07/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Gergely Bertalan
- Department of Radiology Charité–Universitätsmedizin Berlin, Campus Charité MitteBerlin Germany
| | - Jing Guo
- Department of Radiology Charité–Universitätsmedizin Berlin, Campus Charité MitteBerlin Germany
| | - Heiko Tzschätzsch
- Department of Radiology Charité–Universitätsmedizin Berlin, Campus Charité MitteBerlin Germany
| | - Charlotte Klein
- Department of Neurology Charité–Universitätsmedizin Berlin, Campus Charité MitteBerlin Germany
| | - Eric Barnhill
- Department of Radiology Charité–Universitätsmedizin Berlin, Campus Charité MitteBerlin Germany
| | - Ingolf Sack
- Department of Radiology Charité–Universitätsmedizin Berlin, Campus Charité MitteBerlin Germany
| | - Jürgen Braun
- Institute of Medical Informatics Charité–Universitätsmedizin Berlin, Campus Benjamin FranklinBerlin Germany
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215
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Qing B, Canovic EP, Mijailovic AS, Jagielska A, Whitfield MJ, Lowe AL, Kelly EH, Turner D, Sahin M, Van Vliet K. PROBING MECHANICAL PROPERTIES OF BRAIN IN A TUBEROUS SCLEROSIS MODEL OF AUTISM. J Biomech Eng 2018; 141:2709743. [PMID: 30347048 DOI: 10.1115/1.4040945] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Indexed: 01/03/2023]
Abstract
Causes of Autism Spectrum Disorders (ASD) are understood poorly, making diagnosis and treatment challenging. While many studies have investigated the biochemical and genetic aspects of ASD, whether and how mechanical characteristics of the autistic brain can modulate neuronal connectivity and cognition in ASD are unknown. Previously, it has been shown that ASD brains are characterized by abnormal white matter and disorganized neuronal connectivity; we hypothesized that these significant cellular-level structural changes may translate to changes in the mechanical properties of the autistic brain or regions therein. Here, we focused on tuberous sclerosis complex (TSC), a genetic disorder with a high penetrance of ASD. We investigated mechanical differences between murine brains obtained from control and TSC cohorts at various deformation length- and time-scales. At the microscale, we conducted creep-compliance and stress relaxation experiments using atomic force microscope-enabled indentation. At the mesoscale, we conducted impact indentation using a pendulum-based instrumented indenter to extract mechanical energy dissipation metrics. At the macroscale, we used oscillatory shear rheology to quantify the frequency-dependent shear moduli. Despite significant changes in the cellular organization of TSC brain tissue, we found no corresponding changes in the quantified mechanical properties at every length- and time-scale explored. This investigation of the mechanical characteristics of the brain has broadened our understanding of causes and markers of TSC/ASD, while raising questions about whether any mechanical differences can be detected in other animal models of ASD or other disease models that also feature abnormal brain structure.
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Affiliation(s)
- Bo Qing
- Department of Biological Engineering, MIT, Cambridge, MA, USA
| | | | | | - Anna Jagielska
- Department of Materials Science and Engineering, MIT, Cambridge, MA, USA
| | | | - Alexis L Lowe
- Department of Neuroscience, Wellesley College, Wellesley, MA, USA
| | - Elyza H Kelly
- The F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Daria Turner
- The F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Mustafa Sahin
- The F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Krystyn Van Vliet
- Department of Biological Engineering, MIT, Cambridge, MA, USA; Department of Materials Science and Engineering, MIT, Cambridge, MA, USA
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216
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Velasco-Estevez M, Mampay M, Boutin H, Chaney A, Warn P, Sharp A, Burgess E, Moeendarbary E, Dev KK, Sheridan GK. Infection Augments Expression of Mechanosensing Piezo1 Channels in Amyloid Plaque-Reactive Astrocytes. Front Aging Neurosci 2018; 10:332. [PMID: 30405400 PMCID: PMC6204357 DOI: 10.3389/fnagi.2018.00332] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 10/01/2018] [Indexed: 01/07/2023] Open
Abstract
A defining pathophysiological hallmark of Alzheimer's disease (AD) is the amyloid plaque; an extracellular deposit of aggregated fibrillar Aβ1-42 peptides. Amyloid plaques are hard, brittle structures scattered throughout the hippocampus and cerebral cortex and are thought to cause hyperphosphorylation of tau, neurofibrillary tangles, and progressive neurodegeneration. Reactive astrocytes and microglia envelop the exterior of amyloid plaques and infiltrate their inner core. Glia are highly mechanosensitive cells and can almost certainly sense the mismatch between the normally soft mechanical environment of the brain and very stiff amyloid plaques via mechanosensing ion channels. Piezo1, a non-selective cation channel, can translate extracellular mechanical forces to intracellular molecular signaling cascades through a process known as mechanotransduction. Here, we utilized an aging transgenic rat model of AD (TgF344-AD) to study expression of mechanosensing Piezo1 ion channels in amyloid plaque-reactive astrocytes. We found that Piezo1 is upregulated with age in the hippocampus and cortex of 18-month old wild-type rats. However, more striking increases in Piezo1 were measured in the hippocampus of TgF344-AD rats compared to age-matched wild-type controls. Interestingly, repeated urinary tract infections with Escherichia coli bacteria, a common comorbidity in elderly people with dementia, caused further elevations in Piezo1 channel expression in the hippocampus and cortex of TgF344-AD rats. Taken together, we report that aging and peripheral infection augment amyloid plaque-induced upregulation of mechanoresponsive ion channels, such as Piezo1, in astrocytes. Further research is required to investigate the role of astrocytic Piezo1 in the Alzheimer's brain, whether modulating channel opening will protect or exacerbate the disease state, and most importantly, if Piezo1 could prove to be a novel drug target for age-related dementia.
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Affiliation(s)
- María Velasco-Estevez
- Neuroimmulology & Neurotherapeutics Laboratory, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom
- Drug Development, Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Myrthe Mampay
- Neuroimmulology & Neurotherapeutics Laboratory, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom
| | - Hervé Boutin
- Wolfson Molecular Imaging Centre, Faculty of Biology, Medicine and Health and Manchester Academic Health Sciences Centre, The University of Manchester, Manchester, United Kingdom
| | - Aisling Chaney
- Wolfson Molecular Imaging Centre, Faculty of Biology, Medicine and Health and Manchester Academic Health Sciences Centre, The University of Manchester, Manchester, United Kingdom
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Peter Warn
- Evotec (UK) Ltd., Manchester Science Park, Manchester, United Kingdom
| | - Andrew Sharp
- Evotec (UK) Ltd., Manchester Science Park, Manchester, United Kingdom
| | - Ellie Burgess
- Evotec (UK) Ltd., Manchester Science Park, Manchester, United Kingdom
| | - Emad Moeendarbary
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Kumlesh K. Dev
- Drug Development, Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Graham K. Sheridan
- Neuroimmulology & Neurotherapeutics Laboratory, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom
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217
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Freeman R, Han M, Álvarez Z, Lewis JA, Wester JR, Stephanopoulos N, McClendon MT, Lynsky C, Godbe JM, Sangji H, Luijten E, Stupp SI. Reversible self-assembly of superstructured networks. Science 2018; 362:808-813. [PMID: 30287619 DOI: 10.1126/science.aat6141] [Citation(s) in RCA: 204] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 05/29/2018] [Accepted: 09/24/2018] [Indexed: 12/12/2022]
Abstract
Soft structures in nature, such as protein assemblies, can organize reversibly into functional and often hierarchical architectures through noncovalent interactions. Molecularly encoding this dynamic capability in synthetic materials has remained an elusive goal. We report on hydrogels of peptide-DNA conjugates and peptides that organize into superstructures of intertwined filaments that disassemble upon the addition of molecules or changes in charge density. Experiments and simulations demonstrate that this response requires large-scale spatial redistribution of molecules directed by strong noncovalent interactions among them. Simulations also suggest that the chemically reversible structures can only occur within a limited range of supramolecular cohesive energies. Storage moduli of the hydrogels change reversibly as superstructures form and disappear, as does the phenotype of neural cells in contact with these materials.
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Affiliation(s)
- Ronit Freeman
- Simpson Querrey Institute, Northwestern University, Chicago, IL 60611, USA
| | - Ming Han
- Applied Physics Graduate Program, Northwestern University, Evanston, IL 60208, USA
| | - Zaida Álvarez
- Simpson Querrey Institute, Northwestern University, Chicago, IL 60611, USA
| | - Jacob A Lewis
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - James R Wester
- Simpson Querrey Institute, Northwestern University, Chicago, IL 60611, USA
| | | | - Mark T McClendon
- Simpson Querrey Institute, Northwestern University, Chicago, IL 60611, USA
| | - Cheyenne Lynsky
- Simpson Querrey Institute, Northwestern University, Chicago, IL 60611, USA
| | - Jacqueline M Godbe
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | - Hussain Sangji
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Erik Luijten
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA. .,Department of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, IL 60208, USA.,Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA
| | - Samuel I Stupp
- Simpson Querrey Institute, Northwestern University, Chicago, IL 60611, USA. .,Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA.,Department of Chemistry, Northwestern University, Evanston, IL 60208, USA.,Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA.,Department of Medicine, Northwestern University, Chicago, IL 60611, USA
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218
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Canadas RF, Ren T, Tocchio A, Marques AP, Oliveira JM, Reis RL, Demirci U. Tunable anisotropic networks for 3-D oriented neural tissue models. Biomaterials 2018; 181:402-414. [DOI: 10.1016/j.biomaterials.2018.07.055] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Revised: 07/24/2018] [Accepted: 07/28/2018] [Indexed: 02/06/2023]
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219
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Kuhl E. Mechanical Cues in Spinal Cord Injury. Biophys J 2018; 115:751-753. [PMID: 30119835 DOI: 10.1016/j.bpj.2018.04.052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 04/10/2018] [Indexed: 11/25/2022] Open
Affiliation(s)
- Ellen Kuhl
- Departments of Mechanical Engineering and Bioengineering, Stanford University, Stanford, California.
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220
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Mechanical Mapping of Spinal Cord Growth and Repair in Living Zebrafish Larvae by Brillouin Imaging. Biophys J 2018; 115:911-923. [PMID: 30122291 PMCID: PMC6127462 DOI: 10.1016/j.bpj.2018.07.027] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 07/03/2018] [Accepted: 07/25/2018] [Indexed: 12/21/2022] Open
Abstract
The mechanical properties of biological tissues are increasingly recognized as important factors in developmental and pathological processes. Most existing mechanical measurement techniques either necessitate destruction of the tissue for access or provide insufficient spatial resolution. Here, we show for the first time to our knowledge a systematic application of confocal Brillouin microscopy to quantitatively map the mechanical properties of spinal cord tissues during biologically relevant processes in a contact-free and nondestructive manner. Living zebrafish larvae were mechanically imaged in all anatomical planes during development and after spinal cord injury. These experiments revealed that Brillouin microscopy is capable of detecting the mechanical properties of distinct anatomical structures without interfering with the animal’s natural development. The Brillouin shift within the spinal cord remained comparable during development and transiently decreased during the repair processes after spinal cord transection. By taking into account the refractive index distribution, we explicitly determined the apparent longitudinal modulus and viscosity of different larval zebrafish tissues. Importantly, mechanical properties differed between tissues in situ and in excised slices. The presented work constitutes the first step toward an in vivo assessment of spinal cord tissue mechanics during regeneration, provides a methodical basis to identify key determinants of mechanical tissue properties, and allows us to test their relative importance in combination with biochemical and genetic factors during developmental and regenerative processes.
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221
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Abstract
Astrocytes, the neural homeostatic cells, play a key role in the information processing in the central nervous system. They express multiple receptors which respond to a number of chemical messengers and get excited as evidenced by an increase in second messengers in short and delayed time domains. Astrocytes secrete numerous neuroactive agents and mount various homeostatic responses. These signal integrating functions are key factors of neuropathology (better termed astroneuropathology): they provide for neuroprotection through both homeostatic support and astroglial reactivity; failure in astroglial defensive or supporting capabilities facilitates evolution of neurological disorders.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain; Celica, BIOMEDICAL, Technology Park 24, 1000 Ljubljana, Slovenia.
| | - Robert Zorec
- University of Ljubljana, Institute of Pathophysiology, Laboratory of Neuroendocrinology - Molecular Cell Physiology, Zaloška cesta 4, SI-1000, Ljubljana, Slovenia; Celica, BIOMEDICAL, Technology Park 24, 1000 Ljubljana, Slovenia.
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222
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Abstract
Glial cell types were classified less than 100 years ago by del Rio-Hortega. For instance, he correctly surmised that microglia in pathologic central nervous system (CNS) were "voracious monsters" that helped clean the tissue. Although these historical predictions were remarkably accurate, innovative technologies have revealed novel molecular, cellular, and dynamic physiologic aspects of CNS glia. In this review, we integrate recent findings regarding the roles of glia and glial interactions in healthy and injured spinal cord. The three major glial cell types are considered in healthy CNS and after spinal cord injury (SCI). Astrocytes, which in the healthy CNS regulate neurotransmitter and neurovascular dynamics, respond to SCI by becoming reactive and forming a glial scar that limits pathology and plasticity. Microglia, which in the healthy CNS scan for infection/damage, respond to SCI by promoting axon growth and remyelination-but also with hyperactivation and cytotoxic effects. Oligodendrocytes and their precursors, which in healthy tissue speed axon conduction and support axonal function, respond to SCI by differentiating and producing myelin, but are susceptible to death. Thus, post-SCI responses of each glial cell can simultaneously stimulate and stifle repair. Interestingly, potential therapies could also target interactions between these cells. Astrocyte-microglia cross-talk creates a feed-forward loop, so shifting the response of either cell could amplify repair. Astrocytes, microglia, and oligodendrocytes/precursors also influence post-SCI cell survival, differentiation, and remyelination, as well as axon sparing. Therefore, optimizing post-SCI responses of glial cells-and interactions between these CNS cells-could benefit neuroprotection, axon plasticity, and functional recovery.
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Affiliation(s)
- Andrew D Gaudet
- Department of Psychology and Neuroscience, University of Colorado Boulder, Muenzinger D244 | 345 UCB, Boulder, CO, 80309, USA.
- Center for Neuroscience, University of Colorado Boulder, Muenzinger D244 | 345 UCB, Boulder, CO, 80309, USA.
| | - Laura K Fonken
- Division of Pharmacology and Toxicology, University of Texas at Austin, Austin, TX, 78712, USA
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223
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Schaeffer J, Tannahill D, Cioni JM, Rowlands D, Keynes R. Identification of the extracellular matrix protein Fibulin-2 as a regulator of spinal nerve organization. Dev Biol 2018; 442:101-114. [PMID: 29944871 DOI: 10.1016/j.ydbio.2018.06.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 05/24/2018] [Accepted: 06/19/2018] [Indexed: 12/11/2022]
Abstract
During amniote peripheral nervous system development, segmentation ensures the correct patterning of the spinal nerves relative to the vertebral column. Along the antero-posterior (rostro-caudal) axis, each somite-derived posterior half-sclerotome expresses repellent molecules to restrict axon growth and neural crest migration to the permissive anterior half-segment. To identify novel regulators of spinal nerve patterning, we investigated the differential gene expression of anterior and posterior half-sclerotomes in the chick embryo by RNA-sequencing. Several genes encoding extracellular matrix proteins were found to be enriched in either anterior (e.g. Tenascin-C, Laminin alpha 4) or posterior (e.g. Fibulin-2, Fibromodulin, Collagen VI alpha 2) half-sclerotomes. Among them, the extracellular matrix protein Fibulin-2 was found specifically restricted to the posterior half-sclerotome. By using in ovo ectopic expression in chick somites, we found that Fibulin-2 modulates spinal axon growth trajectories in vivo. While no intrinsic axon repellent activity of Fibulin-2 was found, we showed that it enhances the growth cone repulsive activity of Semaphorin 3A in vitro. Some molecules regulating axon growth during development are found to be upregulated in the adult central nervous system (CNS) following traumatic injury. Here, we found increased Fibulin-2 protein levels in reactive astrocytes at the lesion site of a mouse model of CNS injury. Together, these results suggest that the developing vertebral column and the adult CNS share molecular features that control axon growth and plasticity, which may open up the possibility for the identification of novel therapeutic targets for brain and spinal cord injury.
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Affiliation(s)
- Julia Schaeffer
- Department of Physiology, Development and Neuroscience, University of Cambridge, UK.
| | | | - Jean-Michel Cioni
- Department of Physiology, Development and Neuroscience, University of Cambridge, UK
| | | | - Roger Keynes
- Department of Physiology, Development and Neuroscience, University of Cambridge, UK
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224
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Sandvig I, Augestad IL, Håberg AK, Sandvig A. Neuroplasticity in stroke recovery. The role of microglia in engaging and modifying synapses and networks. Eur J Neurosci 2018; 47:1414-1428. [PMID: 29786167 DOI: 10.1111/ejn.13959] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 04/13/2018] [Accepted: 04/17/2018] [Indexed: 02/06/2023]
Abstract
Neuroplasticity after ischaemic injury involves both spontaneous rewiring of neural networks and circuits as well as functional responses in neurogenic niches. These events involve complex interactions with activated microglia, which evolve in a dynamic manner over time. Although the exact mechanisms underlying these interactions remain poorly understood, increasing experimental evidence suggests a determining role of pro- and anti-inflammatory microglial activation profiles in shaping both synaptogenesis and neurogenesis. While the inflammatory response of microglia was thought to be detrimental, a more complex profile of the role of microglia in tissue remodelling is emerging. Experimental evidence suggests that microglia in response to injury can rapidly modify neuronal activity and modulate synaptic function, as well as be beneficial for the proliferation and integration of neural progenitor cells (NPCs) from endogenous neurogenic niches into functional networks thereby supporting stroke recovery. The manner in which microglia contribute towards sculpting neural synapses and networks, both in terms of activity-dependent and homeostatic plasticity, suggests that microglia-mediated pro- and/or anti-inflammatory activity may significantly contribute towards spontaneous neuronal plasticity after ischaemic lesions. In this review, we first introduce some of the key cellular and molecular mechanisms underlying neuroplasticity in stroke and then proceed to discuss the crosstalk between microglia and endogenous neuroplasticity in response to brain ischaemia with special focus on the engagement of synapses and neural networks and their implications for grey matter integrity and function in stroke repair.
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Affiliation(s)
- Ioanna Sandvig
- Faculty of Medicine and Health Sciences, Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Ingrid Lovise Augestad
- Faculty of Medicine and Health Sciences, Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Asta Kristine Håberg
- Faculty of Medicine and Health Sciences, Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,Department of Radiology and Nuclear Medicine, St. Olav's Hospital, Trondheim University Hospital, Trondheim, Norway
| | - Axel Sandvig
- Faculty of Medicine and Health Sciences, Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,Department of Neurology, St Olav's Hospital, Trondheim University Hospital, Trondheim, Norway.,Department of Pharmacology and Clinical Neurosciences, Division of Neuro, Head and Neck, Umeå University Hospital, Umeå, Sweden
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225
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Yang Y, Ren J, Sun Y, Xue Y, Zhang Z, Gong A, Wang B, Zhong Z, Cui Z, Xi Z, Yang GY, Sun Q, Bian L. A connexin43/YAP axis regulates astroglial-mesenchymal transition in hemoglobin induced astrocyte activation. Cell Death Differ 2018; 25:1870-1884. [PMID: 29880858 DOI: 10.1038/s41418-018-0137-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 04/12/2018] [Accepted: 05/16/2018] [Indexed: 01/05/2023] Open
Abstract
Reactive astrogliosis is a common response to insults to the central nervous system, but the mechanism remains unknown. In this study, we found the temporal and spatial differential expression of glial fibrillary acidic protein (GFAP) and Vimentin in the intracerebral hemorrhage (ICH) mouse brain, indicating that the de-differentiation and astroglial-mesenchymal transition (AMT) of astrocytes might be an early event in reactive astrogliosis. Further we verified the AMT finding in purified astrocyte cultures exposed to hemoglobin (Hb). Additionally, Connexin 43 (Cx43) downregulation and YAP nuclear translocation were observed in Hb-activated astrocytes. Knocking down Cx43 by siRNA triggered YAP nuclear translocation. Cx43 and YAP were physically associated as determined by immunofluorescence and co-immunoprecipitation. We propose that astrocytes undergo AMT during Hb-induced activation where Cx43 downregulation facilitates YAP nuclear translocation is a novel mechanism involved in this process. Cx43-YAP interaction may represent a potential therapeutic target for modulating astrocyte activation.
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Affiliation(s)
- Yong Yang
- Department of Neurosurgery, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200025, China.,Department of Neurosurgery, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080, China
| | - Jie Ren
- Department of Neurosurgery, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200025, China
| | - Yuhao Sun
- Department of Neurosurgery, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200025, China
| | - Yuan Xue
- Zhenjiang Center for Disease Control and Prevention, Zhenjiang, 212000, China
| | - Zhijian Zhang
- Basic Medical Science Research Center, School of Medicine, Jiangsu University, Zhenjiang, 212000, China
| | - Aihua Gong
- Basic Medical Science Research Center, School of Medicine, Jiangsu University, Zhenjiang, 212000, China
| | - Baofeng Wang
- Department of Neurosurgery, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200025, China
| | - Zhihong Zhong
- Department of Neurosurgery, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200025, China
| | - Zhenwen Cui
- Department of Neurosurgery, The Affiliated Hospital of Qingdao University, Qingdao, 266000, China
| | - Zhiyu Xi
- Department of Neurosurgery, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200025, China
| | - Guo-Yuan Yang
- Neuroscience and Neuroengineering Research Center, Med-X Research Institute, Shanghai Jiao Tong University, Shanghai, 200030, China
| | - Qingfang Sun
- Department of Neurosurgery, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200025, China. .,Department of Neurosurgery, Ruijin Hospital Luwan Branch, Shanghai Jiao Tong University, Shanghai, 200025, China.
| | - Liuguan Bian
- Department of Neurosurgery, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200025, China.
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226
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Varone A, Rajnicek AM, Huang W. Silkworm silk biomaterials for spinal cord repair: promise for combinatorial therapies. Neural Regen Res 2018; 13:809-810. [PMID: 29863007 PMCID: PMC5998641 DOI: 10.4103/1673-5374.232471] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Affiliation(s)
- Anna Varone
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, UK
| | - Ann Marie Rajnicek
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, UK
| | - Wenlong Huang
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, UK
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227
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Tissue and cellular rigidity and mechanosensitive signaling activation in Alexander disease. Nat Commun 2018; 9:1899. [PMID: 29765022 PMCID: PMC5954157 DOI: 10.1038/s41467-018-04269-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 04/12/2018] [Indexed: 12/22/2022] Open
Abstract
Glial cells have increasingly been implicated as active participants in the pathogenesis of neurological diseases, but critical pathways and mechanisms controlling glial function and secondary non-cell autonomous neuronal injury remain incompletely defined. Here we use models of Alexander disease, a severe brain disorder caused by gain-of-function mutations in GFAP, to demonstrate that misregulation of GFAP leads to activation of a mechanosensitive signaling cascade characterized by activation of the Hippo pathway and consequent increased expression of A-type lamin. Importantly, we use genetics to verify a functional role for dysregulated mechanotransduction signaling in promoting behavioral abnormalities and non-cell autonomous neurodegeneration. Further, we take cell biological and biophysical approaches to suggest that brain tissue stiffness is increased in Alexander disease. Our findings implicate altered mechanotransduction signaling as a key pathological cascade driving neuronal dysfunction and neurodegeneration in Alexander disease, and possibly also in other brain disorders characterized by gliosis. Alexander disease is a rare neurodegeneration caused by mutations in a glial gene GFAP. Here, Wang and colleagues show in animal models of Alexander disease that GFAP mutant brain and cells have greater tissue and cellular stiffness and greater activation of mechanosensitive signaling cascade.
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228
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Functional ectopic neural lobe increases GAP-43 expression via PI3K/AKT pathways to alleviate central diabetes insipidus after pituitary stalk lesion in rats. Neurosci Lett 2018; 673:1-6. [DOI: 10.1016/j.neulet.2018.02.038] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 02/16/2018] [Accepted: 02/16/2018] [Indexed: 02/08/2023]
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229
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Schierbaum N, Hack M, Betz O, Schäffer TE. Macro-SICM: A Scanning Ion Conductance Microscope for Large-Range Imaging. Anal Chem 2018; 90:5048-5054. [PMID: 29569436 DOI: 10.1021/acs.analchem.7b04764] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The scanning ion conductance microscope (SICM) is a versatile, high-resolution imaging technique that uses an electrolyte-filled nanopipet as a probe. Its noncontact imaging principle makes the SICM uniquely suited for the investigation of soft and delicate surface structures in a liquid environment. The SICM has found an ever-increasing number of applications in chemistry, physics, and biology. However, a drawback of conventional SICMs is their relatively small scan range (typically 100 μm × 100 μm in the lateral and 10 μm in the vertical direction). We have developed a Macro-SICM with an exceedingly large scan range of 25 mm × 25 mm in the lateral and 0.25 mm in the vertical direction. We demonstrate the high versatility of the Macro-SICM by imaging at different length scales: from centimeters (fingerprint, coin) to millimeters (bovine tongue tissue, insect wing) to micrometers (cellular extensions). We applied the Macro-SICM to the study of collective cell migration in epithelial wound healing.
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230
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Abstract
Understanding the mechanical behavior of human brain is critical to interpret the role of physical stimuli in both normal and pathological processes that occur in CNS tissue, such as development, inflammation, neurodegeneration, aging, and most common brain tumors. Despite clear evidence that mechanical cues influence both normal and transformed brain tissue activity as well as normal and transformed brain cell behavior, little is known about the links between mechanical signals and their biochemical and medical consequences. A multi-level approach from whole organ rheology to single cell mechanics is needed to understand the physical aspects of human brain function and its pathologies. This review summarizes the latest achievements in the field.
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Affiliation(s)
- Katarzyna Pogoda
- Department of Physiology, University of Pennsylvania, Philadelphia, PA, United States.,Institute of Nuclear Physics, Polish Academy of Sciences, Krakow, Poland
| | - Paul A Janmey
- Department of Physiology, University of Pennsylvania, Philadelphia, PA, United States
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231
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Tissue stiffening coordinates morphogenesis by triggering collective cell migration in vivo. Nature 2018; 554:523-527. [PMID: 29443958 PMCID: PMC6013044 DOI: 10.1038/nature25742] [Citation(s) in RCA: 297] [Impact Index Per Article: 49.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 01/11/2018] [Indexed: 01/04/2023]
Abstract
Collective cell migration (CCM) is essential for morphogenesis, tissue remodelling, and cancer invasion1,2. In vivo, groups of cells move in an orchestrated way through tissues. This movement requires forces and involves mechanical as well as molecular interactions between cells and their environment. While the role of molecular signals in CCM is comparatively well understood1,2, how tissue mechanics influence CCM in vivo remains unknown. Here we investigated the importance of mechanical cues in the collective migration of the Xenopus laevis neural crest cells, an embryonic cell population whose migratory behaviour has been likened to cancer invasion3. We found that, during morphogenesis, the head mesoderm underlying the cephalic neural crest stiffens. This stiffening initiated an epithelial-to-mesenchymal transition (EMT) in neural crest cells and triggered their collective migration. To detect changes in their mechanical environment, neural crest use integrin/vinculin/talin-mediated mechanosensing. By performing mechanical and molecular manipulations, we showed that mesoderm stiffening is necessary and sufficient to trigger neural crest migration. Finally, we demonstrated that convergent extension of the mesoderm, which starts during gastrulation, leads to increased mesoderm stiffness by increasing the cell density underneath the neural crest. These results unveil a novel role for mesodermal convergent extension as a mechanical coordinator of morphogenesis, and thus reveal a new link between two apparently unconnected processes, gastrulation and neural crest migration, via changes in tissue mechanics. Overall, we provide the first demonstration that changes in substrate stiffness can trigger CCM by promoting EMT in vivo. More broadly, our results raise the exciting idea that tissue mechanics combines with molecular effectors to coordinate morphogenesis4.
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232
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Dias DO, Göritz C. Fibrotic scarring following lesions to the central nervous system. Matrix Biol 2018; 68-69:561-570. [PMID: 29428230 DOI: 10.1016/j.matbio.2018.02.009] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 02/05/2018] [Accepted: 02/05/2018] [Indexed: 10/18/2022]
Abstract
Following lesions to the central nervous system, scar tissue forms at the lesion site. Injury often severs axons and scar tissue is thought to block axonal regeneration, resulting in permanent functional deficits. While scar-forming astrocytes have been extensively studied, much less attention has been given to the fibrotic, non-glial component of the scar. We here review recent progress in understanding fibrotic scar formation following different lesions to the brain and spinal cord. We specifically highlight recent evidence for pericyte-derived fibrotic scar tissue formation, discussing the origin, recruitment, function and therapeutic relevance of fibrotic scarring.
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Affiliation(s)
- David Oliveira Dias
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Christian Göritz
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
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233
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Tanaka A, Fujii Y, Kasai N, Okajima T, Nakashima H. Regulation of neuritogenesis in hippocampal neurons using stiffness of extracellular microenvironment. PLoS One 2018; 13:e0191928. [PMID: 29408940 PMCID: PMC5800654 DOI: 10.1371/journal.pone.0191928] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 01/15/2018] [Indexed: 11/19/2022] Open
Abstract
The mechanosensitivity of neurons in the central nervous system (CNS) is an interesting issue as regards understanding neuronal development and designing compliant materials as neural interfaces between neurons and external devices for treating CNS injuries and disorders. Although neurite initiation from a cell body is known to be the first step towards forming a functional nervous network during development or regeneration, less is known about how the mechanical properties of the extracellular microenvironment affect neuritogenesis. Here, we investigated the filamentous actin (F-actin) cytoskeletal structures of neurons, which are a key factor in neuritogenesis, on gel substrates with a stiffness-controlled substrate, to reveal the relationship between substrate stiffness and neuritogenesis. We found that neuritogenesis was significantly suppressed on a gel substrate with an elastic modulus higher than the stiffness of in vivo brain. Fluorescent images of the F-actin cytoskeletal structures showed that the F-actin organization depended on the substrate stiffness. Circumferential actin meshworks and arcs were formed at the edge of the cell body on the stiff gel substrates unlike with soft substrates. The suppression of F-actin cytoskeleton formation improved neuritogenesis. The results indicate that the organization of neuronal F-actin cytoskeletons is strongly regulated by the mechanical properties of the surrounding environment, and the mechanically-induced F-actin cytoskeletons regulate neuritogenesis.
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Affiliation(s)
- Aya Tanaka
- NTT Basic Research Laboratories NTT Corporation, Atsugi, Kanagawa, Japan
- * E-mail:
| | - Yuki Fujii
- Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Nahoko Kasai
- NTT Basic Research Laboratories NTT Corporation, Atsugi, Kanagawa, Japan
| | - Takaharu Okajima
- Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Hiroshi Nakashima
- NTT Basic Research Laboratories NTT Corporation, Atsugi, Kanagawa, Japan
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234
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Führmann T, Anandakumaran PN, Payne SL, Pakulska MM, Varga BV, Nagy A, Tator C, Shoichet MS. Combined delivery of chondroitinase ABC and human induced pluripotent stem cell-derived neuroepithelial cells promote tissue repair in an animal model of spinal cord injury. ACTA ACUST UNITED AC 2018; 13:024103. [PMID: 29083317 DOI: 10.1088/1748-605x/aa96dc] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The lack of tissue regeneration after traumatic spinal cord injury in animal models is largely attributed to the local inhibitory microenvironment. To overcome this inhibitory environment while promoting tissue regeneration, we investigated the combined delivery of chondroitinase ABC (chABC) with human induced pluripotent stem cell-derived neuroepithelial stem cells (NESCs). ChABC was delivered to the injured spinal cord at the site of injury by affinity release from a crosslinked methylcellulose (MC) hydrogel by injection into the intrathecal space. NESCs were distributed in a hydrogel comprised of hyaluronan and MC and injected into the spinal cord tissue both rostral and caudal to the site of injury. Cell transplantation led to reduced cavity formation, but did not improve motor function. While few surviving cells were found 2 weeks post injury, the majority of live cells were neurons, with only few astrocytes, oligodendrocytes, and progenitor cells. At 9 weeks post injury, there were more progenitor cells and a more even distribution of cell types compared to those at 2 weeks post injury, suggesting preferential survival and differentiation. Interestingly, animals that received cells and chABC had more neurons than animals that received cells alone, suggesting that chABC influenced the injury environment such that neuronal differentiation or survival was favoured.
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Affiliation(s)
- Tobias Führmann
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, M5S 3E1, Canada. Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, M5S 3E1, Canada
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235
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Heindryckx F, Li JP. Role of proteoglycans in neuro-inflammation and central nervous system fibrosis. Matrix Biol 2018; 68-69:589-601. [PMID: 29382609 DOI: 10.1016/j.matbio.2018.01.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 12/26/2017] [Accepted: 01/20/2018] [Indexed: 12/19/2022]
Abstract
Fibrosis is defined as the thickening and scarring of connective tissue, usually as a consequence of tissue damage. The central nervous system (CNS) is special in the sense that fibrogenic cells are restricted to vascular and meningeal areas. Inflammation and the disruption of the blood-brain barrier can lead to the infiltration of fibroblasts and trigger fibrotic response. While the initial function of the fibrotic tissue is to restore the blood-brain barrier and to limit the site of injury, it also demolishes the structure of extracellular matrix and impedes the healing process by producing inhibitory molecules and forming a physical and biochemical barrier that prevents axon regeneration. As a major constituent in the extracellular matrix, proteoglycans participate in the neuro-inflammation, modulating the fibrotic process. In this review, we will discuss the pathophysiology of fibrosis during acute injuries of the CNS, as well as during chronic neurodegenerative conditions such as Alzheimer's disease, Parkinson's disease, multiple sclerosis and age-related neurodegeneration with focus on the functional roles of proteoglycans.
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Affiliation(s)
- Femke Heindryckx
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Jin-Ping Li
- Department of Medical Biochemistry and Microbiology/SciLifeLab, Uppsala University, Uppsala, Sweden.
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236
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Espinosa-Hoyos D, Jagielska A, Homan KA, Du H, Busbee T, Anderson DG, Fang NX, Lewis JA, Van Vliet KJ. Engineered 3D-printed artificial axons. Sci Rep 2018; 8:478. [PMID: 29323240 PMCID: PMC5765144 DOI: 10.1038/s41598-017-18744-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 12/16/2017] [Indexed: 12/02/2022] Open
Abstract
Myelination is critical for transduction of neuronal signals, neuron survival and normal function of the nervous system. Myelin disorders account for many debilitating neurological diseases such as multiple sclerosis and leukodystrophies. The lack of experimental models and tools to observe and manipulate this process in vitro has constrained progress in understanding and promoting myelination, and ultimately developing effective remyelination therapies. To address this problem, we developed synthetic mimics of neuronal axons, representing key geometric, mechanical, and surface chemistry components of biological axons. These artificial axons exhibit low mechanical stiffness approaching that of a human axon, over unsupported spans that facilitate engagement and wrapping by glial cells, to enable study of myelination in environments reflecting mechanical cues that neurons present in vivo. Our 3D printing approach provides the capacity to vary independently the complex features of the artificial axons that can reflect specific states of development, disease, or injury. Here, we demonstrate that oligodendrocytes' production and wrapping of myelin depend on artificial axon stiffness, diameter, and ligand coating. This biofidelic platform provides direct visualization and quantification of myelin formation and myelinating cells' response to both physical cues and pharmacological agents.
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Affiliation(s)
- Daniela Espinosa-Hoyos
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Biosystems & Micromechanics Interdisciplinary Research Group (BioSyM), Singapore-MIT Alliance in Research & Technology (SMART), Singapore, Singapore
| | - Anna Jagielska
- Biosystems & Micromechanics Interdisciplinary Research Group (BioSyM), Singapore-MIT Alliance in Research & Technology (SMART), Singapore, Singapore
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Kimberly A Homan
- Wyss Institute for Biologically Inspired Engineering, Cambridge, MA, 02138, USA
- School of Engineering and Applied Sciences, Harvard University, Harvard, MA, 02138, USA
| | - Huifeng Du
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Travis Busbee
- Wyss Institute for Biologically Inspired Engineering, Cambridge, MA, 02138, USA
- School of Engineering and Applied Sciences, Harvard University, Harvard, MA, 02138, USA
| | - Daniel G Anderson
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Institute for Medical Engineering and Sciences, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Harvard-MIT Division of Health Sciences & Technology, Cambridge, MA, 02139, USA
| | - Nicholas X Fang
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Jennifer A Lewis
- Wyss Institute for Biologically Inspired Engineering, Cambridge, MA, 02138, USA
- School of Engineering and Applied Sciences, Harvard University, Harvard, MA, 02138, USA
| | - Krystyn J Van Vliet
- Biosystems & Micromechanics Interdisciplinary Research Group (BioSyM), Singapore-MIT Alliance in Research & Technology (SMART), Singapore, Singapore.
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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237
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Holle AW, Young JL, Van Vliet KJ, Kamm RD, Discher D, Janmey P, Spatz JP, Saif T. Cell-Extracellular Matrix Mechanobiology: Forceful Tools and Emerging Needs for Basic and Translational Research. NANO LETTERS 2018; 18:1-8. [PMID: 29178811 PMCID: PMC5842374 DOI: 10.1021/acs.nanolett.7b04982] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Extracellular biophysical cues have a profound influence on a wide range of cell behaviors, including growth, motility, differentiation, apoptosis, gene expression, adhesion, and signal transduction. Cells not only respond to definitively mechanical cues from the extracellular matrix (ECM) but can also sometimes alter the mechanical properties of the matrix and hence influence subsequent matrix-based cues in both physiological and pathological processes. Interactions between cells and materials in vitro can modify cell phenotype and ECM structure, whether intentionally or inadvertently. Interactions between cell and matrix mechanics in vivo are of particular importance in a wide variety of disorders, including cancer, central nervous system injury, fibrotic diseases, and myocardial infarction. Both the in vitro and in vivo effects of this coupling between mechanics and biology hold important implications for clinical applications.
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Affiliation(s)
- Andrew W Holle
- Department of Cellular Biophysics, Max Planck Institute for Medical Research , Jahnstraße 29, 69120 Heidelberg, Germany
- Institute of Physical Chemistry, University of Heidelberg , 69117 Heidelberg, Germany
| | - Jennifer L Young
- Department of Cellular Biophysics, Max Planck Institute for Medical Research , Jahnstraße 29, 69120 Heidelberg, Germany
- Institute of Physical Chemistry, University of Heidelberg , 69117 Heidelberg, Germany
| | - Krystyn J Van Vliet
- BioSystems & Micromechanics IRG, Singapore-MIT Alliance in Research and Technology , Singapore
| | - Roger D Kamm
- BioSystems & Micromechanics IRG, Singapore-MIT Alliance in Research and Technology , Singapore
| | | | | | - Joachim P Spatz
- Department of Cellular Biophysics, Max Planck Institute for Medical Research , Jahnstraße 29, 69120 Heidelberg, Germany
- Institute of Physical Chemistry, University of Heidelberg , 69117 Heidelberg, Germany
| | - Taher Saif
- Department of Mechanical Sciences and Engineering, University of Illinois at Urbana-Champaign , 1206 West Green Street, Urbana, Illinois 61801, United States
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238
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Weber IP, Yun SH, Scarcelli G, Franze K. The role of cell body density in ruminant retina mechanics assessed by atomic force and Brillouin microscopy. Phys Biol 2017; 14:065006. [PMID: 28406094 DOI: 10.1088/1478-3975/aa6d18] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Cells in the central nervous system (CNS) respond to the stiffness of their environment. CNS tissue is mechanically highly heterogeneous, thus providing motile cells with region-specific mechanical signals. While CNS mechanics has been measured with a variety of techniques, reported values of tissue stiffness vary greatly, and the morphological structures underlying spatial changes in tissue stiffness remain poorly understood. We here exploited two complementary techniques, contact-based atomic force microscopy and contact-free Brillouin microscopy, to determine the mechanical properties of ruminant retinae, which are built up by different tissue layers. As in all vertebrate retinae, layers of high cell body densities ('nuclear layers') alternate with layers of low cell body densities ('plexiform layers'). Different tissue layers varied significantly in their mechanical properties, with the photoreceptor layer being the stiffest region of the retina, and the inner plexiform layer belonging to the softest regions. As both techniques yielded similar results, our measurements allowed us to calibrate the Brillouin microscopy measurements and convert the Brillouin shift into a quantitative assessment of elastic tissue stiffness with optical resolution. Similar as in the mouse spinal cord and the developing Xenopus brain, we found a strong correlation between nuclear densities and tissue stiffness. Hence, the cellular composition of retinae appears to strongly contribute to local tissue stiffness, and Brillouin microscopy shows a great potential for the application in vivo to measure the mechanical properties of transparent tissues.
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Affiliation(s)
- Isabell P Weber
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
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239
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Huang G, Li F, Zhao X, Ma Y, Li Y, Lin M, Jin G, Lu TJ, Genin GM, Xu F. Functional and Biomimetic Materials for Engineering of the Three-Dimensional Cell Microenvironment. Chem Rev 2017; 117:12764-12850. [PMID: 28991456 PMCID: PMC6494624 DOI: 10.1021/acs.chemrev.7b00094] [Citation(s) in RCA: 457] [Impact Index Per Article: 65.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The cell microenvironment has emerged as a key determinant of cell behavior and function in development, physiology, and pathophysiology. The extracellular matrix (ECM) within the cell microenvironment serves not only as a structural foundation for cells but also as a source of three-dimensional (3D) biochemical and biophysical cues that trigger and regulate cell behaviors. Increasing evidence suggests that the 3D character of the microenvironment is required for development of many critical cell responses observed in vivo, fueling a surge in the development of functional and biomimetic materials for engineering the 3D cell microenvironment. Progress in the design of such materials has improved control of cell behaviors in 3D and advanced the fields of tissue regeneration, in vitro tissue models, large-scale cell differentiation, immunotherapy, and gene therapy. However, the field is still in its infancy, and discoveries about the nature of cell-microenvironment interactions continue to overturn much early progress in the field. Key challenges continue to be dissecting the roles of chemistry, structure, mechanics, and electrophysiology in the cell microenvironment, and understanding and harnessing the roles of periodicity and drift in these factors. This review encapsulates where recent advances appear to leave the ever-shifting state of the art, and it highlights areas in which substantial potential and uncertainty remain.
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Affiliation(s)
- Guoyou Huang
- MOE Key Laboratory of Biomedical Information
Engineering, School of Life Science and Technology, Xi’an Jiaotong
University, Xi’an 710049, People’s Republic of China
- Bioinspired Engineering and Biomechanics Center
(BEBC), Xi’an Jiaotong University, Xi’an 710049, People’s
Republic of China
| | - Fei Li
- Bioinspired Engineering and Biomechanics Center
(BEBC), Xi’an Jiaotong University, Xi’an 710049, People’s
Republic of China
- Department of Chemistry, School of Science,
Xi’an Jiaotong University, Xi’an 710049, People’s Republic
of China
| | - Xin Zhao
- Bioinspired Engineering and Biomechanics Center
(BEBC), Xi’an Jiaotong University, Xi’an 710049, People’s
Republic of China
- Interdisciplinary Division of Biomedical
Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong,
People’s Republic of China
| | - Yufei Ma
- MOE Key Laboratory of Biomedical Information
Engineering, School of Life Science and Technology, Xi’an Jiaotong
University, Xi’an 710049, People’s Republic of China
- Bioinspired Engineering and Biomechanics Center
(BEBC), Xi’an Jiaotong University, Xi’an 710049, People’s
Republic of China
| | - Yuhui Li
- MOE Key Laboratory of Biomedical Information
Engineering, School of Life Science and Technology, Xi’an Jiaotong
University, Xi’an 710049, People’s Republic of China
- Bioinspired Engineering and Biomechanics Center
(BEBC), Xi’an Jiaotong University, Xi’an 710049, People’s
Republic of China
| | - Min Lin
- MOE Key Laboratory of Biomedical Information
Engineering, School of Life Science and Technology, Xi’an Jiaotong
University, Xi’an 710049, People’s Republic of China
- Bioinspired Engineering and Biomechanics Center
(BEBC), Xi’an Jiaotong University, Xi’an 710049, People’s
Republic of China
| | - Guorui Jin
- MOE Key Laboratory of Biomedical Information
Engineering, School of Life Science and Technology, Xi’an Jiaotong
University, Xi’an 710049, People’s Republic of China
- Bioinspired Engineering and Biomechanics Center
(BEBC), Xi’an Jiaotong University, Xi’an 710049, People’s
Republic of China
| | - Tian Jian Lu
- Bioinspired Engineering and Biomechanics Center
(BEBC), Xi’an Jiaotong University, Xi’an 710049, People’s
Republic of China
- MOE Key Laboratory for Multifunctional Materials
and Structures, Xi’an Jiaotong University, Xi’an 710049,
People’s Republic of China
| | - Guy M. Genin
- MOE Key Laboratory of Biomedical Information
Engineering, School of Life Science and Technology, Xi’an Jiaotong
University, Xi’an 710049, People’s Republic of China
- Bioinspired Engineering and Biomechanics Center
(BEBC), Xi’an Jiaotong University, Xi’an 710049, People’s
Republic of China
- Department of Mechanical Engineering &
Materials Science, Washington University in St. Louis, St. Louis 63130, MO,
USA
- NSF Science and Technology Center for
Engineering MechanoBiology, Washington University in St. Louis, St. Louis 63130,
MO, USA
| | - Feng Xu
- MOE Key Laboratory of Biomedical Information
Engineering, School of Life Science and Technology, Xi’an Jiaotong
University, Xi’an 710049, People’s Republic of China
- Bioinspired Engineering and Biomechanics Center
(BEBC), Xi’an Jiaotong University, Xi’an 710049, People’s
Republic of China
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240
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Russell LN, Lampe KJ. Oligodendrocyte Precursor Cell Viability, Proliferation, and Morphology is Dependent on Mesh Size and Storage Modulus in 3D Poly(ethylene glycol)-Based Hydrogels. ACS Biomater Sci Eng 2017; 3:3459-3468. [PMID: 33445383 DOI: 10.1021/acsbiomaterials.7b00374] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Oligodendrocytes in the central nervous system (CNS) are responsible for generating myelin, an electrically insulating layer around neuronal axons. When myelin is damaged, neurons are incapable of sustaining normal communications, which can manifest in patients as pain and loss of mobility and vision. A plethora of research has used biomaterials to promote neuronal regeneration, but despite the wide implications of a disrupted myelin sheath, very little is known about how biomaterial environments impact proliferation of oligodendrocyte precursor cells (OPCs) or their differentiation into myelinating oligodendrocytes. This work investigates how the storage modulus and mesh size of a polyethylene glycol (PEG)-based hydrogel, varied via two different mechanisms, directly affect the proliferation of two OPC lines encapsulated and cultured in 3D. Viability and proliferation of both OPC lines was dependent on hydrogel swelling and stiffness, where the concentration of ATP increased more in the more compliant gels. OPCs multiplied in the 3D hydrogels, creating significantly larger spheroids in the less cross-linked conditions. Stiffer, more highly cross-linked materials lead to greater expression of PDGFRα, an OPC receptor, indicating that fewer cells were committed to the oligodendrocyte lineage or had dedifferentiated in compliant materials. Laminin incorporation in the 3D matrix was found to have little effect on viability or proliferation. These findings provide valuable information on how mesh size and stiffness affect OPCs where more compliant materials favor proliferation of OPCs with less commitment to a mature oligodendrocyte lineage. Such information will be useful in the development of translational biomaterials to stimulate oligodendrocyte maturation for neural regeneration.
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Affiliation(s)
- Lauren N Russell
- Department of Chemical Engineering, University of Virginia, 102 Engineers' Way, Charlottesville, Virginia 22904, United States
| | - Kyle J Lampe
- Department of Chemical Engineering, University of Virginia, 102 Engineers' Way, Charlottesville, Virginia 22904, United States
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241
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Beekmans SV, Emanuel KS, Smit TH, Iannuzzi D. Minimally Invasive Micro-Indentation: mapping tissue mechanics at the tip of an 18G needle. Sci Rep 2017; 7:11364. [PMID: 28900134 PMCID: PMC5595846 DOI: 10.1038/s41598-017-10526-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 08/10/2017] [Indexed: 01/07/2023] Open
Abstract
Experiments regarding the mechanical properties of soft tissues mostly rely on data collected on specimens that are extracted from their native environment. During the extraction and in the time period between the extraction and the completion of the measurements, however, the specimen may undergo structural changes which could generate unwanted artifacts. To further investigate the role of mechanics in physiology and possibly use it in clinical practices, it is thus of paramount importance to develop instruments that could measure the viscoelastic response of a tissue without necessarily excising it. Tantalized by this opportunity, we have designed a minimally invasive micro-indenter that is able to probe the mechanical response of soft tissues, in situ, via an 18G needle. Here, we discuss its working principle and validate its usability by mapping the viscoelastic properties of a complex, confined sample, namely, the nucleus pulposus of the intervertebral disc. Our findings show that the mechanical properties of a biological tissue in its local environment may be indeed different than those that one would measure after excision, and thus confirm that, to better understand the role of mechanics in life sciences, one should always perform minimally invasive measurements like those that we have here introduced.
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Affiliation(s)
- Steven V Beekmans
- Department of Physics and Astronomy and LaserLab Amsterdam, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081, HV, Amsterdam, Netherlands.
| | - Kaj S Emanuel
- Department of Orthopaedic Surgery, VU University Medical Center (VUmc), Amsterdam Movement Sciences, De Boelelaan 1117, 1081 HV, Amsterdam, Netherlands
| | - Theodoor H Smit
- Department of Medical Biology and Department of Orthopedic Surgery, Academic Medical Center (AMC), Meiberdreef 9, 1105 AZ, Amsterdam, Netherlands
| | - Davide Iannuzzi
- Department of Physics and Astronomy and LaserLab Amsterdam, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081, HV, Amsterdam, Netherlands
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242
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Smolyakov G, Dague E, Roux C, Seguelas MH, Galés C, Senard JM, Arvanitis DN. Nanoscale structural mapping as a measure of maturation in the murine frontal cortex. Brain Struct Funct 2017; 223:255-265. [PMID: 28779306 DOI: 10.1007/s00429-017-1486-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 07/26/2017] [Indexed: 01/01/2023]
Abstract
Atomic force microscopy (AFM) is emerging as an innovative tool to phenotype the brain. This study demonstrates the utility of AFM to determine nanomechanical and nanostructural features of the murine dorsolateral frontal cortex from weaning to adulthood. We found an increase in tissue stiffness of the primary somatosensory cortex with age, along with an increased cortical mechanical heterogeneity. To characterize the features potentially responsible for this heterogeneity, we applied AFM scan mode to directly image the topography of thin sections of the primary somatosensory cortical layers II/III, IV and V/VI. Topographical mapping of the cortical layers at successive ages showed progressive smoothing of the surface. Topographical images were also compared with histochemically derived morphological information, which demonstrated the deposition of perineuronal nets, important extracellular components and markers of maturity. Our work demonstrates that high-resolution AFM images can be used to determine the nanostructural properties of cortical maturation, well beyond embryonic and postnatal development. Furthermore, it may offer a new method for brain phenotyping and screening to uncover topographical changes in early stages of neurodegenerative diseases.
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Affiliation(s)
- G Smolyakov
- LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, France
- ITAV-CNRS, Université de Toulouse, CNRS, Toulouse, France
| | - E Dague
- LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, France.
- ITAV-CNRS, Université de Toulouse, CNRS, Toulouse, France.
| | - C Roux
- LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, France
- ITAV-CNRS, Université de Toulouse, CNRS, Toulouse, France
- Laboratoire Des IMRCP, Université de Toulouse, CNRS UMR 5623, Université de Toulouse, 118 Route de Narbonne, 31062, Toulouse Cedex 9, France
- Institut Des Maladies Métaboliques Et Cardiovasculaires, INSERM, UMR1048, Université de Toulouse, 118 Route de Narbonne, 31062, Toulouse Cedex 9, France
| | - M H Seguelas
- Institut Des Maladies Métaboliques Et Cardiovasculaires, INSERM, UMR1048, Université de Toulouse, 118 Route de Narbonne, 31062, Toulouse Cedex 9, France
| | - C Galés
- ITAV-CNRS, Université de Toulouse, CNRS, Toulouse, France
- Institut Des Maladies Métaboliques Et Cardiovasculaires, INSERM, UMR1048, Université de Toulouse, 118 Route de Narbonne, 31062, Toulouse Cedex 9, France
| | - J M Senard
- Institut Des Maladies Métaboliques Et Cardiovasculaires, INSERM, UMR1048, Université de Toulouse, 118 Route de Narbonne, 31062, Toulouse Cedex 9, France
| | - D N Arvanitis
- Institut Des Maladies Métaboliques Et Cardiovasculaires, INSERM, UMR1048, Université de Toulouse, 118 Route de Narbonne, 31062, Toulouse Cedex 9, France.
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243
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The mechanical importance of myelination in the central nervous system. J Mech Behav Biomed Mater 2017; 76:119-124. [PMID: 28462864 DOI: 10.1016/j.jmbbm.2017.04.017] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Accepted: 04/12/2017] [Indexed: 02/06/2023]
Abstract
Neurons in the central nervous system are surrounded and cross-linked by myelin, a fatty white substance that wraps around axons to create an electrically insulating layer. The electrical function of myelin is widely recognized; yet, its mechanical importance remains underestimated. Here we combined nanoindentation testing and histological staining to correlate brain stiffness to the degree of myelination in immature, pre-natal brains and mature, post-natal brains. We found that both gray and white matter tissue stiffened significantly (p≪0.001) upon maturation: the gray matter stiffness doubled from 0.31±0.20kPa pre-natally to 0.68±0.20kPa post-natally; the white matter stiffness tripled from 0.45±0.18kPa pre-natally to 1.33±0.64kPa post-natally. At the same time, the white matter myelin content increased significantly (p≪0.001) from 58±2% to 74±9%. White matter stiffness and myelin content were correlated with a Pearson correlation coefficient of ρ=0.92 (p≪0.001). Our study suggests that myelin is not only important to ensure smooth electrical signal propagation in neurons, but also to protect neurons against physical forces and provide a strong microstructural network that stiffens the white matter tissue as a whole. Our results suggest that brain tissue stiffness could serve as a biomarker for multiple sclerosis and other forms of demyelinating disorders. Understanding how tissue maturation translates into changes in mechanical properties and knowing the precise brain stiffness at different stages of life has important medical implications in development, aging, and neurodegeneration.
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