1
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Hosseindokht Z, Davoudi S, Rahdar M, Janahmadi M, Kolahdouz M, Sasanpoour P. Photoacoustic viscoelasticity assessment of prefrontal cortex and cerebellum in normal and prenatal valproic acid-exposed rats. PHOTOACOUSTICS 2024; 36:100590. [PMID: 38318427 PMCID: PMC10839762 DOI: 10.1016/j.pacs.2024.100590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 11/11/2023] [Accepted: 01/18/2024] [Indexed: 02/07/2024]
Abstract
Mechanical properties of brain tissues are from principal features from different points of view; diagnosis, the performance of the brain and neurological disorders. Particularly viscoelastic properties of the brain tissues are determinative. In this study based on a proposed accurate and non-invasive method, we have measured the viscoelastic properties of prefrontal cortex and cerebellum, two important brain regions involved in motor learning and pathophysiology of autism spectrum disorder (ASD). In this regard, using photoacoustic systems, viscoelastic properties of tissues from the cerebellum and prefrontal cortex of normal and prenatal VPA (Valproic acid)-exposed (i.e. autistic-like) offspring rats are measured. Results of our study show that the cerebellums of normal tissues are stiffer than the tissue obtained from autistic-like rats, while the viscoelasticity of the prefrontal cortex of normal tissues is higher than that of autistic ones. The proposed method for the measurement of viscoelastic properties of the brain tissue has the potential not only for the fundamental studies but as a diagnosis technique.
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Affiliation(s)
- Zahra Hosseindokht
- School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, Iran
| | - Shima Davoudi
- Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mona Rahdar
- Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mahyar Janahmadi
- Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammadreza Kolahdouz
- School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, Iran
| | - Pezhman Sasanpoour
- Department of Medical Physics and Biomedical Engineering, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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2
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Mirzakhel Z, Reddy GA, Boman J, Manns B, Veer ST, Katira P. "Patchiness" in mechanical stiffness across a tumor as an early-stage marker for malignancy. BMC Ecol Evol 2024; 24:33. [PMID: 38486161 PMCID: PMC10938681 DOI: 10.1186/s12862-024-02221-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Accepted: 03/03/2024] [Indexed: 03/17/2024] Open
Abstract
Mechanical phenotyping of tumors, either at an individual cell level or tumor cell population level is gaining traction as a diagnostic tool. However, the extent of diagnostic and prognostic information that can be gained through these measurements is still unclear. In this work, we focus on the heterogeneity in mechanical properties of cells obtained from a single source such as a tissue or tumor as a potential novel biomarker. We believe that this heterogeneity is a conventionally overlooked source of information in mechanical phenotyping data. We use mechanics-based in-silico models of cell-cell interactions and cell population dynamics within 3D environments to probe how heterogeneity in cell mechanics drives tissue and tumor dynamics. Our simulations show that the initial heterogeneity in the mechanical properties of individual cells and the arrangement of these heterogenous sub-populations within the environment can dictate overall cell population dynamics and cause a shift towards the growth of malignant cell phenotypes within healthy tissue environments. The overall heterogeneity in the cellular mechanotype and their spatial distributions is quantified by a "patchiness" index, which is the ratio of the global to local heterogeneity in cell populations. We observe that there exists a threshold value of the patchiness index beyond which an overall healthy population of cells will show a steady shift towards a more malignant phenotype. Based on these results, we propose that the "patchiness" of a tumor or tissue sample, can be an early indicator for malignant transformation and cancer occurrence in benign tumors or healthy tissues. Additionally, we suggest that tissue patchiness, measured either by biochemical or biophysical markers, can become an important metric in predicting tissue health and disease likelihood just as landscape patchiness is an important metric in ecology.
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Affiliation(s)
- Zibah Mirzakhel
- Department of Mechanical Engineering, San Diego State University, San Diego, CA, USA
| | - Gudur Ashrith Reddy
- Department of Mechanical Engineering, San Diego State University, San Diego, CA, USA
- Department of Bioengineering, University of California San Diego, San Diego, CA, USA
| | - Jennifer Boman
- Department of Mechanical Engineering, San Diego State University, San Diego, CA, USA
| | - Brianna Manns
- Department of Mechanical Engineering, San Diego State University, San Diego, CA, USA
| | - Savannah Ter Veer
- Department of Mechanical Engineering, San Diego State University, San Diego, CA, USA
| | - Parag Katira
- Department of Mechanical Engineering, San Diego State University, San Diego, CA, USA.
- Computational Science Research Center, San Diego State University, San Diego, CA, USA.
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3
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Pillai EK, Franze K. Mechanics in the nervous system: From development to disease. Neuron 2024; 112:342-361. [PMID: 37967561 DOI: 10.1016/j.neuron.2023.10.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 09/29/2023] [Accepted: 10/04/2023] [Indexed: 11/17/2023]
Abstract
Physical forces are ubiquitous in biological processes across scales and diverse contexts. This review highlights the significance of mechanical forces in nervous system development, homeostasis, and disease. We provide an overview of mechanical signals present in the nervous system and delve into mechanotransduction mechanisms translating these mechanical cues into biochemical signals. During development, mechanical cues regulate a plethora of processes, including cell proliferation, differentiation, migration, network formation, and cortex folding. Forces then continue exerting their influence on physiological processes, such as neuronal activity, glial cell function, and the interplay between these different cell types. Notably, changes in tissue mechanics manifest in neurodegenerative diseases and brain tumors, potentially offering new diagnostic and therapeutic target opportunities. Understanding the role of cellular forces and tissue mechanics in nervous system physiology and pathology adds a new facet to neurobiology, shedding new light on many processes that remain incompletely understood.
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Affiliation(s)
- Eva K Pillai
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK; Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany; Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany.
| | - Kristian Franze
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK; Institute of Medical Physics and Microtissue Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Henkestraße 91, 91052 Erlangen, Germany; Max-Planck-Zentrum für Physik und Medizin, Kussmaulallee 1, 91054 Erlangen, Germany.
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4
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Silva RV, Morr AS, Herthum H, Koch SP, Mueller S, Batzdorf CS, Bertalan G, Meyer T, Tzschätzsch H, Kühl AA, Boehm-Sturm P, Braun J, Scheel M, Paul F, Infante-Duarte C, Sack I. Cortical matrix remodeling as a hallmark of relapsing-remitting neuroinflammation in MR elastography and quantitative MRI. Acta Neuropathol 2024; 147:8. [PMID: 38175305 PMCID: PMC10766667 DOI: 10.1007/s00401-023-02658-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 11/03/2023] [Accepted: 11/23/2023] [Indexed: 01/05/2024]
Abstract
Multiple sclerosis (MS) is a chronic neuroinflammatory disease that involves both white and gray matter. Although gray matter damage is a major contributor to disability in MS patients, conventional clinical magnetic resonance imaging (MRI) fails to accurately detect gray matter pathology and establish a clear correlation with clinical symptoms. Using magnetic resonance elastography (MRE), we previously reported global brain softening in MS and experimental autoimmune encephalomyelitis (EAE). However, it needs to be established if changes of the spatiotemporal patterns of brain tissue mechanics constitute a marker of neuroinflammation. Here, we use advanced multifrequency MRE with tomoelastography postprocessing to investigate longitudinal and regional inflammation-induced tissue changes in EAE and in a small group of MS patients. Surprisingly, we found reversible softening in synchrony with the EAE disease course predominantly in the cortex of the mouse brain. This cortical softening was associated neither with a shift of tissue water compartments as quantified by T2-mapping and diffusion-weighted MRI, nor with leukocyte infiltration as seen by histopathology. Instead, cortical softening correlated with transient structural remodeling of perineuronal nets (PNNs), which involved abnormal chondroitin sulfate expression and microgliosis. These mechanisms also appear to be critical in humans with MS, where tomoelastography for the first time demonstrated marked cortical softening. Taken together, our study shows that neuroinflammation (i) critically affects the integrity of PNNs in cortical brain tissue, in a reversible process that correlates with disease disability in EAE, (ii) reduces the mechanical integrity of brain tissue rather than leading to water accumulation, and (iii) shows similar spatial patterns in humans and mice. These results raise the prospect of leveraging MRE and quantitative MRI for MS staging and monitoring treatment in affected patients.
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Affiliation(s)
- Rafaela V Silva
- Experimental and Clinical Research Center, a cooperation between the Max Delbrück Center for Molecular Medicine in the Helmholtz Association and Charité - Universitätsmedizin Berlin, Berlin, Germany
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, ECRC - Experimental and Clinical Research Center, Berlin, Germany
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
- Charité - Universitätsmedizin Berlin, Einstein Center for Neurosciences Berlin, Berlin, Germany
| | - Anna S Morr
- Charité - Universitätsmedizin Berlin, Department of Radiology, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Helge Herthum
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Center for Advanced Neuroimaging, Berlin, Germany
| | - Stefan P Koch
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Experimental Neurology and Center for Stroke Research Berlin, Berlin, Germany
- Charité-Universitätsmedizin Berlin, NeuroCure Cluster of Excellence and Charité Core Facility 7T Experimental MRI, Berlin, Germany
| | - Susanne Mueller
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Experimental Neurology and Center for Stroke Research Berlin, Berlin, Germany
- Charité-Universitätsmedizin Berlin, NeuroCure Cluster of Excellence and Charité Core Facility 7T Experimental MRI, Berlin, Germany
| | - Clara S Batzdorf
- Experimental and Clinical Research Center, a cooperation between the Max Delbrück Center for Molecular Medicine in the Helmholtz Association and Charité - Universitätsmedizin Berlin, Berlin, Germany
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, ECRC - Experimental and Clinical Research Center, Berlin, Germany
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Gergely Bertalan
- Charité - Universitätsmedizin Berlin, Department of Radiology, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Tom Meyer
- Charité - Universitätsmedizin Berlin, Department of Radiology, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Heiko Tzschätzsch
- Charité - Universitätsmedizin Berlin, Department of Radiology, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Anja A Kühl
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, iPATH.Berlin, Berlin, Germany
| | - Philipp Boehm-Sturm
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Experimental Neurology and Center for Stroke Research Berlin, Berlin, Germany
- Charité-Universitätsmedizin Berlin, NeuroCure Cluster of Excellence and Charité Core Facility 7T Experimental MRI, Berlin, Germany
| | - Jürgen Braun
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Informatics, Berlin, Germany
| | - Michael Scheel
- Charité - Universitätsmedizin Berlin Corporate, Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, NeuroCure Clinical Research Center, Berlin, Germany
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Department of Neuroradiology, Berlin, Germany
| | - Friedemann Paul
- Experimental and Clinical Research Center, a cooperation between the Max Delbrück Center for Molecular Medicine in the Helmholtz Association and Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Carmen Infante-Duarte
- Experimental and Clinical Research Center, a cooperation between the Max Delbrück Center for Molecular Medicine in the Helmholtz Association and Charité - Universitätsmedizin Berlin, Berlin, Germany.
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, ECRC - Experimental and Clinical Research Center, Berlin, Germany.
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany.
| | - Ingolf Sack
- Charité - Universitätsmedizin Berlin, Department of Radiology, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany.
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5
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Carnicer-Lombarte A, Barone DG, Wronowski F, Malliaras GG, Fawcett JW, Franze K. Regenerative capacity of neural tissue scales with changes in tissue mechanics post injury. Biomaterials 2023; 303:122393. [PMID: 37977006 DOI: 10.1016/j.biomaterials.2023.122393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 10/23/2023] [Accepted: 11/05/2023] [Indexed: 11/19/2023]
Abstract
Spinal cord injuries have devastating consequences for humans, as mammalian neurons of the central nervous system (CNS) cannot regenerate. In the peripheral nervous system (PNS), however, neurons may regenerate to restore lost function following injury. While mammalian CNS tissue softens after injury, how PNS tissue mechanics changes in response to mechanical trauma is currently poorly understood. Here we characterised mechanical rat nerve tissue properties before and after in vivo crush and transection injuries using atomic force microscopy-based indentation measurements. Unlike CNS tissue, PNS tissue significantly stiffened after both types of tissue damage. This nerve tissue stiffening strongly correlated with an increase in collagen I levels. Schwann cells, which crucially support PNS regeneration, became more motile and proliferative on stiffer substrates in vitro, suggesting that changes in tissue stiffness may play a key role in facilitating or impeding nervous system regeneration.
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Affiliation(s)
- Alejandro Carnicer-Lombarte
- John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0PY, UK; Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, CB2 3DY, UK; Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, UK.
| | - Damiano G Barone
- John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0PY, UK
| | - Filip Wronowski
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, UK
| | - George G Malliaras
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, UK
| | - James W Fawcett
- John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0PY, UK; Centre for Reconstructive Neuroscience, Institute for Experimental Medicine CAS, Prague, Czech Republic
| | - Kristian Franze
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, CB2 3DY, UK; Institute of Medical Physics and Micro-Tissue Engineering, Friedrich-Alexander Universität Erlangen-Nürnberg, 91052, Erlangen, Germany; Max-Planck-Zentrum für Physik und Medizin, 91054, Erlangen, Germany.
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6
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Yang F, Ding W, Fu X, Chen W, Tang J. Photoacoustic elasto-viscography and optical coherence microscopy for multi-parametric ex vivo brain imaging. BIOMEDICAL OPTICS EXPRESS 2023; 14:5615-5628. [PMID: 38021134 PMCID: PMC10659785 DOI: 10.1364/boe.503847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 09/22/2023] [Accepted: 09/22/2023] [Indexed: 12/01/2023]
Abstract
Optical coherence microscopy (OCM) has shown the importance of imaging ex vivo brain slices at the microscopic level for a better understanding of the disease pathology and mechanism. However, the current OCM-based techniques are mainly limited to providing the tissue's optical properties, such as the attenuation coefficient, scattering coefficient, and cell architecture. Imaging the tissue's mechanical properties, including the elasticity and viscosity, in addition to the optical properties, to provide a comprehensive multi-parametric assessment of the sample has remained a challenge. Here, we present an integrated photoacoustic elasto-viscography (PAEV) and OCM imaging system to measure the sample's optical absorption coefficient, attenuation coefficient, and mechanical properties, including elasticity and viscosity. The obtained mechanical and optical properties were consistent with anatomical features observed in the PAEV and OCM images. The elasticity and viscosity maps showed rich variations of microstructural mechanical properties of mice brain. In the reconstructed elasto-viscogram of brain slices, greater elasticity, and lower viscosity were observed in white matter than in gray matter. With the ability to provide multi-parametric properties of the sample, the PAEV-OCM system holds the potential for a more comprehensive study of brain disease pathology.
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Affiliation(s)
- Fen Yang
- Department of Biomedical Engineering, Guangdong Provincial Key Laboratory of Advanced Biomaterials, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Wenguo Ding
- Department of Biomedical Engineering, Guangdong Provincial Key Laboratory of Advanced Biomaterials, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Xinlei Fu
- Department of Biomedical Engineering, Guangdong Provincial Key Laboratory of Advanced Biomaterials, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Wei Chen
- Department of Biomedical Engineering, Guangdong Provincial Key Laboratory of Advanced Biomaterials, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Jianbo Tang
- Department of Biomedical Engineering, Guangdong Provincial Key Laboratory of Advanced Biomaterials, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
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7
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Fuhs T, Flachmeyer B, Krueger M, Blietz A, Härtig W, Michalski D. Combining atomic force microscopy and fluorescence-based techniques to explore mechanical properties of naive and ischemia-affected brain regions in mice. Sci Rep 2023; 13:12774. [PMID: 37550347 PMCID: PMC10406906 DOI: 10.1038/s41598-023-39277-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Accepted: 07/22/2023] [Indexed: 08/09/2023] Open
Abstract
Knowledge of the brain's structure and function is essential for understanding processes in health and disease. Histochemical and fluorescence-based techniques have proven beneficial in characterizing brain regions and cellular compositions in pre-clinical research. Atomic force microscopy (AFM) has been introduced for mechanical tissue characterization, which may also help investigate pathophysiological aspects in disease-related models such as stroke. While combining AFM and fluorescence-based techniques, this study explored the mechanical properties of naive and ischemic brain regions in mice. Ischemia-affected regions were identified by the green signal of fluorescein isothiocyanate-conjugated albumin. A semi-automated protocol based on a brain atlas allowed regional allocations to the neocortex, striatum, thalamus, hypothalamus, hippocampus, and fiber tracts. Although AFM led to varying measurements, intra-individual analyses indicated a gradually increased tissue stiffness in the neocortex compared to subcortical areas, i.e., the striatum and fiber tracts. Regions affected by ischemia predominantly exhibited an increased tissue stiffness compared to those of the contra-lateral hemisphere, which might be related to cellular swelling. This study indicated intra-individual differences in mechanical properties among naive and ischemia-affected brain regions. The combination of AFM, semi-automated regional allocations, and fluorescence-based techniques thus qualifies for mechanical characterizations of the healthy and disease-affected brain in pre-clinical research.
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Affiliation(s)
- Thomas Fuhs
- Section of Soft Matter Physics, Faculty of Physics and Geosciences, University of Leipzig, Linnéstr. 5, 04103, Leipzig, Germany
- Institute for Physical Chemistry, Faculty of Chemistry and Physics, Technical University Freiberg, Leipziger Str. 29, 09599, Freiberg, Germany
| | - Bianca Flachmeyer
- Institute of Anatomy, Medical Faculty, University of Leipzig, Liebigstr. 13, 04103, Leipzig, Germany
| | - Martin Krueger
- Institute of Anatomy, Medical Faculty, University of Leipzig, Liebigstr. 13, 04103, Leipzig, Germany
| | - Alexandra Blietz
- Department of Neurology, Medical Faculty, University of Leipzig, Liebigstr. 20, 04103, Leipzig, Germany
| | - Wolfgang Härtig
- Paul Flechsig Institute for Brain Research, Medical Faculty, University of Leipzig, Liebigstr. 19, 04103, Leipzig, Germany
| | - Dominik Michalski
- Department of Neurology, Medical Faculty, University of Leipzig, Liebigstr. 20, 04103, Leipzig, Germany.
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8
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Hall CM, Lasli S, Serwinski B, Djordjevic B, Sheridan GK, Moeendarbary E. Hippocampus of the APP NL-G-F mouse model of Alzheimer's disease exhibits region-specific tissue softening concomitant with elevated astrogliosis. Front Aging Neurosci 2023; 15:1212212. [PMID: 37547743 PMCID: PMC10398960 DOI: 10.3389/fnagi.2023.1212212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 07/03/2023] [Indexed: 08/08/2023] Open
Abstract
Widespread neurodegeneration, enlargement of cerebral ventricles, and atrophy of cortical and hippocampal brain structures are classic hallmarks of Alzheimer's disease (AD). Prominent macroscopic disturbances to the cytoarchitecture of the AD brain occur alongside changes in the mechanical properties of brain tissue, as reported in recent magnetic resonance elastography (MRE) measurements of human brain mechanics. Whilst MRE has many advantages, a significant shortcoming is its spatial resolution. Higher resolution "cellular scale" assessment of the mechanical alterations to brain regions involved in memory formation, such as the hippocampus, could provide fresh new insight into the etiology of AD. Characterization of brain tissue mechanics at the cellular length scale is the first stepping-stone to understanding how mechanosensitive neurons and glia are impacted by neurodegenerative disease-associated changes in their microenvironment. To provide insight into the microscale mechanics of aging brain tissue, we measured spatiotemporal changes in the mechanical properties of the hippocampus using high resolution atomic force microscopy (AFM) indentation tests on acute brain slices from young and aged wild-type mice and the APPNL-G-F mouse model. Several hippocampal regions in APPNL-G-F mice are significantly softer than age-matched wild-types, notably the dentate granule cell layer and the CA1 pyramidal cell layer. Interestingly, regional softening coincides with an increase in astrocyte reactivity, suggesting that amyloid pathology-mediated alterations to the mechanical properties of brain tissue may impact the function of mechanosensitive astrocytes. Our data also raise questions as to whether aberrant mechanotransduction signaling could impact the susceptibility of neurons to cellular stressors in their microenvironment.
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Affiliation(s)
- Chloe M. Hall
- Department of Mechanical Engineering, University College London, London, United Kingdom
- School of Applied Sciences, University of Brighton, Brighton, United Kingdom
| | - Soufian Lasli
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Bianca Serwinski
- Department of Mechanical Engineering, University College London, London, United Kingdom
- 199 Biotechnologies Ltd., London, United Kingdom
- Faculty of Social Sciences, Northeastern University London, London, United Kingdom
| | - Boris Djordjevic
- Department of Mechanical Engineering, University College London, London, United Kingdom
- 199 Biotechnologies Ltd., London, United Kingdom
| | - Graham K. Sheridan
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Emad Moeendarbary
- Department of Mechanical Engineering, University College London, London, United Kingdom
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