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Lindhardt TB, Skoven CS, Bordoni L, Østergaard L, Liang Z, Hansen B. Anesthesia-related brain microstructure modulations detected by diffusion magnetic resonance imaging. NMR IN BIOMEDICINE 2024; 37:e5033. [PMID: 37712335 DOI: 10.1002/nbm.5033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 07/06/2023] [Accepted: 08/09/2023] [Indexed: 09/16/2023]
Abstract
Recent studies have shown significant changes to brain microstructure during sleep and anesthesia. In vivo optical microscopy and magnetic resonance imaging (MRI) studies have attributed these changes to anesthesia and sleep-related modulation of the brain's extracellular space (ECS). Isoflurane anesthesia is widely used in preclinical diffusion MRI (dMRI) and it is therefore important to investigate if the brain's microstructure is affected by anesthesia to an extent detectable with dMRI. Here, we employ diffusion kurtosis imaging (DKI) to assess brain microstructure in the awake and anesthetized mouse brain (n = 22). We find both mean diffusivity (MD) and mean kurtosis (MK) to be significantly decreased in the anesthetized mouse brain compared with the awake state (p < 0.001 for both). This effect is observed in both gray matter and white matter. To further investigate the time course of these changes we introduce a method for time-resolved fast DKI. With this, we show the time course of the microstructural alterations in mice (n = 5) as they transition between states in an awake-anesthesia-awake paradigm. We find that the decrease in MD and MK occurs rapidly after delivery of gas isoflurane anesthesia and that values normalize only slowly when the animals return to the awake state. Finally, time-resolved fast DKI is employed in an experimental mouse model of brain edema (n = 4), where cell swelling causes the ECS volume to decrease. Our results show that isoflurane affects DKI parameters and metrics of brain microstructure and point to isoflurane causing a reduction in the ECS volume. The demonstrated DKI methods are suitable for in-bore perturbation studies, for example, for investigating microstructural modulations related to sleep/wake-dependent functions of the glymphatic system. Importantly, our study shows an effect of isoflurane anesthesia on rodent brain microstructure that has broad relevance to preclinical dMRI.
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Affiliation(s)
- Thomas Beck Lindhardt
- Center of Functionally Integrative Neuroscience, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- Sino-Danish Center for Education and Research, Aarhus, Denmark
- University of the Chinese Academy of Sciences, Beijing, China
| | - Christian Stald Skoven
- Center of Functionally Integrative Neuroscience, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Luca Bordoni
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Letten Center, University of Oslo, Oslo, Norway
| | - Leif Østergaard
- Center of Functionally Integrative Neuroscience, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- Department of Radiology, Neuroradiology Research Unit, Aarhus University Hospital, Aarhus, Denmark
| | - Zhifeng Liang
- CAS Center for Excellence in Brain Sciences and Intelligence Technology, Institute of Neuroscience, Chinese Academy of Sciences, Shanghai, China
| | - Brian Hansen
- Center of Functionally Integrative Neuroscience, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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Gao Z. Strategies for enhanced gene delivery to the central nervous system. NANOSCALE ADVANCES 2024; 6:3009-3028. [PMID: 38868835 PMCID: PMC11166101 DOI: 10.1039/d3na01125a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Accepted: 04/12/2024] [Indexed: 06/14/2024]
Abstract
The delivery of genes to the central nervous system (CNS) has been a persistent challenge due to various biological barriers. The blood-brain barrier (BBB), in particular, hampers the access of systemically injected drugs to parenchymal cells, allowing only a minimal percentage (<1%) to pass through. Recent scientific insights highlight the crucial role of the extracellular space (ECS) in governing drug diffusion. Taking into account advancements in vectors, techniques, and knowledge, the discussion will center on the most notable vectors utilized for gene delivery to the CNS. This review will explore the influence of the ECS - a dynamically regulated barrier-on drug diffusion. Furthermore, we will underscore the significance of employing remote-control technologies to facilitate BBB traversal and modulate the ECS. Given the rapid progress in gene editing, our discussion will also encompass the latest advances focused on delivering therapeutic editing in vivo to the CNS tissue. In the end, a brief summary on the impact of Artificial Intelligence (AI)/Machine Learning (ML), ultrasmall, soft endovascular robots, and high-resolution endovascular cameras on improving the gene delivery to the CNS will be provided.
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Affiliation(s)
- Zhenghong Gao
- Mechanical Engineering, The University of Texas at Dallas USA
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3
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Siri S, Burchett A, Datta M. Simulating the Impact of Tumor Mechanical Forces on Glymphatic Networks in the Brain Parenchyma. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.18.594808. [PMID: 38826201 PMCID: PMC11142116 DOI: 10.1101/2024.05.18.594808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Background The brain glymphatic system is currently being explored in the context of many neurological disorders and diseases, including traumatic brain injury, Alzheimer's disease, and ischemic stroke. However, little is known about the impact of brain tumors on glymphatic function. Mechanical forces generated during tumor development and growth may be responsible for compromised glymphatic transport pathways, reducing waste clearance and cerebrospinal fluid (CSF) transport in the brain parenchyma. One such force is solid stress, i.e., growth-induced forces from cell hyperproliferation and excess matrix deposition. Because there are no prior studies assessing the impact of tumor-derived solid stress on glymphatic system structure and performance in the brain parenchyma, this study serves to fill an important gap in the field. Methods We adapted a previously developed Electrical Analog Model using MATLAB Simulink for glymphatic transport coupled with Finite Element Analysis for tumor mechanical stresses and strains in COMSOL. This allowed simulation of the impact of tumor mechanical force generation on fluid transport within brain parenchymal glymphatic units - which include paravascular spaces, astrocytic networks, interstitial spaces, and capillary basement membranes. We conducted a parametric analysis to compare the contributions of tumor size, tumor proximity, and ratio of glymphatic subunits to the stress and strain experienced by the glymphatic unit and corresponding reduction in flow rate of CSF. Results Mechanical stresses intensify with proximity to the tumor and increasing tumor size, highlighting the vulnerability of nearby glymphatic units to tumor-derived forces. Our stress and strain profiles reveal compressive deformation of these surrounding glymphatics and demonstrate that varying the relative contributions of astrocytes vs. interstitial spaces impact the resulting glymphatic structure significantly under tumor mechanical forces. Increased tumor size and proximity caused increased stress and strain across all glymphatic subunits, as does decreased astrocyte composition. Indeed, our model reveals an inverse correlation between extent of astrocyte contribution to the composition of the glymphatic unit and the resulting mechanical stress. This increased mechanical strain across the glymphatic unit decreases the venous efflux rate of CSF, dependent on the degree of strain and the specific glymphatic subunit of interest. For example, a 20% mechanical strain on capillary basement membranes does not significantly decrease venous efflux (2% decrease in flow rates), while the same magnitude of strain on astrocyte networks and interstitial spaces decreases efflux flow rates by 7% and 22%, respectively. Conclusion Our simulations reveal that solid stress from brain tumors directly reduces glymphatic fluid transport, independently from biochemical effects from cancer cells. Understanding these pathophysiological implications is crucial for developing targeted interventions aimed at restoring effective waste clearance mechanisms in the brain.This study opens potential avenues for future experimental research in brain tumor-related glymphatic dysfunction.
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Pierzchala K, Hadjihambi A, Mosso J, Jalan R, Rose CF, Cudalbu C. Lessons on brain edema in HE: from cellular to animal models and clinical studies. Metab Brain Dis 2024; 39:403-437. [PMID: 37606786 PMCID: PMC10957693 DOI: 10.1007/s11011-023-01269-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 07/24/2023] [Indexed: 08/23/2023]
Abstract
Brain edema is considered as a common feature associated with hepatic encephalopathy (HE). However, its central role as cause or consequence of HE and its implication in the development of the neurological alterations linked to HE are still under debate. It is now well accepted that type A and type C HE are biologically and clinically different, leading to different manifestations of brain edema. As a result, the findings on brain edema/swelling in type C HE are variable and sometimes controversial. In the light of the changing natural history of liver disease, better description of the clinical trajectory of cirrhosis and understanding of molecular mechanisms of HE, and the role of brain edema as a central component in the pathogenesis of HE is revisited in the current review. Furthermore, this review highlights the main techniques to measure brain edema and their advantages/disadvantages together with an in-depth description of the main ex-vivo/in-vivo findings using cell cultures, animal models and humans with HE. These findings are instrumental in elucidating the role of brain edema in HE and also in designing new multimodal studies by performing in-vivo combined with ex-vivo experiments for a better characterization of brain edema longitudinally and of its role in HE, especially in type C HE where water content changes are small.
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Affiliation(s)
- Katarzyna Pierzchala
- CIBM Center for Biomedical Imaging, Lausanne, Switzerland.
- Animal Imaging and Technology, EPFL, Lausanne, Switzerland.
| | - Anna Hadjihambi
- The Roger Williams Institute of Hepatology London, Foundation for Liver Research, London, SE5 9NT, UK
- Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - Jessie Mosso
- CIBM Center for Biomedical Imaging, Lausanne, Switzerland
- Animal Imaging and Technology, EPFL, Lausanne, Switzerland
- Laboratory for Functional and Metabolic Imaging (LIFMET), EPFL, Lausanne, Switzerland
| | - Rajiv Jalan
- Liver Failure Group, Institute for Liver and Digestive Health, University College London, Royal Free Campus, London, UK
- European Foundation for the Study of Chronic Liver Failure (EF Clif), Barcelona, Spain
| | - Christopher F Rose
- Hépato-Neuro Laboratory, Centre de Recherche du Centre Hospitalier de l', Université de Montréal (CRCHUM), Montreal, QC, H2X 0A9, Canada
- Department of Medicine, Faculty of Medicine, Université de Montréal, QC, Montreal, H3T 1J4, Canada
| | - Cristina Cudalbu
- CIBM Center for Biomedical Imaging, Lausanne, Switzerland.
- Animal Imaging and Technology, EPFL, Lausanne, Switzerland.
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do Nascimento Amorim MDS, Silva França ÁR, Santos-Oliveira R, Rodrigues Sanches J, Marinho Melo T, Araújo Serra Pinto B, Barbosa LRS, Alencar LMR. Atomic Force Microscopy Applied to the Study of Tauopathies. ACS Chem Neurosci 2024; 15:699-715. [PMID: 38305187 DOI: 10.1021/acschemneuro.3c00819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2024] Open
Abstract
Atomic force microscopy (AFM) is a scanning probe microscopy technique which has a physical principle, the measurement of interatomic forces between a very thin tip and the surface of a sample, allowing the obtaining of quantitative data at the nanoscale, contributing to the surface study and mechanical characterization. Due to its great versatility, AFM has been used to investigate the structural and nanomechanical properties of several inorganic and biological materials, including neurons affected by tauopathies. Tauopathies are neurodegenerative diseases featured by aggregation of phosphorylated tau protein inside neurons, leading to functional loss and progressive neurotoxicity. In the broad universe of neurodegenerative diseases, tauopathies comprise the most prevalent, with Alzheimer's disease as its main representative. This review highlights the use of AFM as a suitable research technique for the study of cellular damages in tauopathies, even in early stages, allowing elucidation of pathogenic mechanisms of these diseases.
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Affiliation(s)
- Maria do Socorro do Nascimento Amorim
- Laboratory of Biophysics and Nanosystems, Department of Physics, Federal University of Maranhão, Campus Bacanga, São Luís 65080-805, Maranhão, Brazil
| | - Álefe Roger Silva França
- Laboratory of Biophysics and Nanosystems, Department of Physics, Federal University of Maranhão, Campus Bacanga, São Luís 65080-805, Maranhão, Brazil
| | - Ralph Santos-Oliveira
- Nuclear Engineering Institute, Brazilian Nuclear Energy Commission, Rio de Janeiro 21941906, Brazil
- Laboratory of Nanoradiopharmacy, Rio de Janeiro State University, Rio de Janeiro 23070200, Brazil
| | - Jonas Rodrigues Sanches
- Laboratory of Experimental Physiology, Department of Physiological Sciences, Federal University of Maranhão, Campus Bacanga, São Luís, 65080-805, Maranhão, Brazil
| | - Thamys Marinho Melo
- Laboratory of Experimental Physiology, Department of Physiological Sciences, Federal University of Maranhão, Campus Bacanga, São Luís, 65080-805, Maranhão, Brazil
| | - Bruno Araújo Serra Pinto
- Laboratory of Experimental Physiology, Department of Physiological Sciences, Federal University of Maranhão, Campus Bacanga, São Luís, 65080-805, Maranhão, Brazil
| | - Leandro R S Barbosa
- Department of General Physics, Institute of Physics, University of São Paulo, São Paulo 05508-000, SP, Brazil
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas 13083-100, SP, Brazil
| | - Luciana Magalhães Rebelo Alencar
- Laboratory of Biophysics and Nanosystems, Department of Physics, Federal University of Maranhão, Campus Bacanga, São Luís 65080-805, Maranhão, Brazil
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Inavalli VVGK, Puente Muñoz V, Draffin JE, Tønnesen J. Fluorescence microscopy shadow imaging for neuroscience. Front Cell Neurosci 2024; 18:1330100. [PMID: 38425431 PMCID: PMC10902105 DOI: 10.3389/fncel.2024.1330100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 02/01/2024] [Indexed: 03/02/2024] Open
Abstract
Fluorescence microscopy remains one of the single most widely applied experimental approaches in neuroscience and beyond and is continuously evolving to make it easier and more versatile. The success of the approach is based on synergistic developments in imaging technologies and fluorophore labeling strategies that have allowed it to greatly diversify and be used across preparations for addressing structure as well as function. Yet, while targeted labeling strategies are a key strength of fluorescence microscopy, they reciprocally impose general limitations on the possible types of experiments and analyses. One recent development that overcomes some of these limitations is fluorescence microscopy shadow imaging, where membrane-bound cellular structures remain unlabeled while the surrounding extracellular space is made to fluoresce to provide a negative contrast shadow image. When based on super-resolution STED microscopy, the technique in effect provides a positive image of the extracellular space geometry and entire neuropil in the field of view. Other noteworthy advantages include the near elimination of the adverse effects of photobleaching and toxicity in live imaging, exhaustive and homogeneous labeling across the preparation, and the ability to apply and adjust the label intensity on the fly. Shadow imaging is gaining popularity and has been applied on its own or combined with conventional positive labeling to visualize cells and synaptic proteins in their parenchymal context. Here, we highlight the inherent limitations of fluorescence microscopy and conventional labeling and contrast these against the pros and cons of recent shadow imaging approaches. Our aim is to describe the brief history and current trajectory of the shadow imaging technique in the neuroscience field, and to draw attention to its ease of application and versatility.
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Affiliation(s)
| | - Virginia Puente Muñoz
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), Leioa, Spain
- Neuronal Excitability Lab, Achucarro Basque Center for Neuroscience, Leioa, Spain
| | - Jonathan E. Draffin
- Neuronal Excitability Lab, Achucarro Basque Center for Neuroscience, Leioa, Spain
- Aligning Science Across Parkinson’s (ASAP), Collaborative Research Network, Chevy Chase, MD, United States
| | - Jan Tønnesen
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), Leioa, Spain
- Neuronal Excitability Lab, Achucarro Basque Center for Neuroscience, Leioa, Spain
- Aligning Science Across Parkinson’s (ASAP), Collaborative Research Network, Chevy Chase, MD, United States
- Instituto Biofisika (CSIC/UPV), Leioa, Spain
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Xiong H, Wilson BA, Ge X, Gao X, Cai Q, Xu X, Bachoo R, Qin Z. Glioblastoma Margin as a Diffusion Barrier Revealed by Photoactivation of Plasmonic Nanovesicles. NANO LETTERS 2024; 24:1570-1578. [PMID: 38287297 DOI: 10.1021/acs.nanolett.3c04101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2024]
Abstract
Glioblastoma (GBM) is the most complex and lethal primary brain cancer. Adequate drug diffusion and penetration are essential for treating GBM, but how the spatial heterogeneity in GBM impacts drug diffusion and transport is poorly understood. Herein, we report a new method, photoactivation of plasmonic nanovesicles (PANO), to measure molecular diffusion in the extracellular space of GBM. By examining three genetically engineered GBM mouse models that recapitulate key clinical features including the angiogenic core and diffuse infiltration, we found that the tumor margin has the lowest diffusion coefficient (highest tortuosity) compared with the tumor core and surrounding brain tissue. Analysis of the cellular composition shows that tortuosity in the GBM is strongly correlated with neuronal loss and astrocyte activation. Our all-optical measurement reveals the heterogeneous GBM microenvironment and highlights the tumor margin as a diffusion barrier for drug transport in the brain, with implications for therapeutic delivery.
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Affiliation(s)
- Hejian Xiong
- Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510000, China
- Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Blake A Wilson
- Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Xiaoqian Ge
- Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
- Department of Biomedical Engineering, University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
| | - Xiaofei Gao
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
| | - Qi Cai
- Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
- Department of Biological and Agricultural Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Xueqi Xu
- Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Robert Bachoo
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
| | - Zhenpeng Qin
- Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
- Department of Biomedical Engineering, University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
- Department of Bioengineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
- Center for Advanced Pain Studies, The University of Texas at Dallas, Richardson, Texas 75080, United States
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Xiong H, Wilson BA, Ge X, Gao X, Cai Q, Xu X, Bachoo R, Qin Z. Glioblastoma Margin as a Diffusion Barrier Revealed by Photoactivation of Plasmonic Nanovesicles. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.29.564569. [PMID: 37961149 PMCID: PMC10634930 DOI: 10.1101/2023.10.29.564569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Glioblastoma (GBM) is the most complex and lethal adult primary brain cancer. Adequate drug diffusion and penetration are essential for treating GBM, but how the spatial heterogeneity in GBM impacts drug diffusion and transport is poorly understood. Herein, we report a new method, photoactivation of plasmonic nanovesicles (PANO), to measure molecular diffusion in the extracellular space of GBM. By examining three genetically engineered GBM mouse models that recapitulate key clinical features including angiogenic core and diffuse infiltration, we found that the tumor margin has the lowest diffusion coefficient (highest tortuosity) compared with the tumor core and surrounding brain tissue. Analysis of the cellular composition shows that the tortuosity in the GBM is strongly correlated with neuronal loss and astrocyte activation. Our all-optical measurement reveals the heterogeneous GBM microenvironment and highlights the tumor margin as a diffusion barrier for drug transport in the brain, with implications for therapeutic delivery.
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Nicholson C. Sheet and void porous media models for brain interstitial space. J R Soc Interface 2023; 20:20230223. [PMID: 37553990 PMCID: PMC10410222 DOI: 10.1098/rsif.2023.0223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 07/19/2023] [Indexed: 08/10/2023] Open
Abstract
The interstitial space (ISS) component of brain extracellular space resembles an unconsolidated porous medium. Previous analysis of the diffusion of small molecules in this domain shows that the typical porosity is 0.2 and typical tortuosity 1.6. An ensemble of cubic cells separated by uniform sheets of ISS cannot generate the measured tortuosity, even if some of the tortuosity value is attributed to interstitial viscosity, so more complex models are needed. Here two models are analysed: the corner cubic void (CCV) and the edge tunnel void (ETV). Both models incorporate dead spaces formed from local expansions of the ISS to increase geometrical tortuosity. Using Monte Carlo simulation of diffusion it is found that in the range of normal porosities, the square of the tortuosity is a linear function of the ratio of void to sheet volumes for the CCV model and this model can generate the experimentally observed tortuosities. For abnormally high porosities, however, the linear relation fails. The ETV model shows a quartic functional relation and can only generate the observed tortuosity if interstitial viscosity is present. The CCV model is used to analyse the recently described changes in porosity between asleep and awake brain states.
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Affiliation(s)
- Charles Nicholson
- Department of Neuroscience and Physiology, New York University Grossman School of Medicine, New York, NY 10016, USA
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10
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Xiong H, Wilson BA, Slesinger PA, Qin Z. Understanding Neuropeptide Transmission in the Brain by Optical Uncaging and Release. ACS Chem Neurosci 2023; 14:516-523. [PMID: 36719384 PMCID: PMC10302814 DOI: 10.1021/acschemneuro.2c00684] [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] [Indexed: 02/01/2023] Open
Abstract
Neuropeptides are abundant and essential signaling molecules in the nervous system involved in modulating neural circuits and behavior. Neuropeptides are generally released extrasynaptically and signal via volume transmission through G-protein-coupled receptors (GPCR). Although substantive functional roles of neuropeptides have been discovered, many questions on neuropeptide transmission remain poorly understood, including the local diffusion and transmission properties in the brain extracellular space. To address this challenge, intensive efforts are required to develop advanced tools for releasing and detecting neuropeptides with high spatiotemporal resolution. Because of the rapid development of biosensors and materials science, emerging tools are beginning to provide a better understanding of neuropeptide transmission. In this perspective, we summarize the fundamental advances in understanding neuropeptide transmission over the past decade, highlight the tools for releasing neuropeptides with high spatiotemporal solution in the brain, and discuss open questions and future directions in the field.
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Affiliation(s)
- Hejian Xiong
- Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Blake A. Wilson
- Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Paul A. Slesinger
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Zhenpeng Qin
- Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, TX 75080, USA
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080, USA
- Department of Surgery, The University of Texas at Southwestern Medical Center, Dallas, TX 75390, USA
- Center for Advanced Pain Studies, The University of Texas at Dallas, Richardson, TX 75080, USA
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11
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Choi BK, Katoch N, Park JA, Kim JW, Oh TI, Kim HJ, Woo EJ. Measurement of extracellular volume fraction using magnetic resonance-based conductivity tensor imaging. Front Physiol 2023. [DOI: 10.3389/fphys.2023.132911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
Conductivity tensor imaging (CTI) using MRI is an advanced method that can non-invasively measure the electrical properties of living tissues. The contrast of CTI is based on underlying hypothesis about the proportionality between the mobility and diffusivity of ions and water molecules inside tissues. The experimental validation of CTI in both in vitro and in vivo settings is required as a reliable tool to assess tissue conditions. The changes in extracellular space can be indicators for disease progression, such as fibrosis, edema, and cell swelling. In this study, we conducted a phantom imaging experiment to test the feasibility of CTI for measuring the extracellular volume fraction in biological tissue. To mimic tissue conditions with different extracellular volume fractions, four chambers of giant vesicle suspension (GVS) with different vesicle densities were included in the phantom. The reconstructed CTI images of the phantom were compared with the separately-measured conductivity spectra of the four chambers using an impedance analyzer. Moreover, the values of the estimated extracellular volume fraction in each chamber were compared with those measured by a spectrophotometer. As the vesicle density increased, we found that the extracellular volume fraction, extracellular diffusion coefficient, and low-frequency conductivity decreased, while the intracellular diffusion coefficient slightly increased. On the other hand, the high-frequency conductivity could not clearly distinguish the four chambers. The extracellular volume fraction measured by the spectrophotometer and CTI method in each chamber were quite comparable, i.e., (1.00, 0.98 ± 0.01), (0.59, 0.63 ± 0.02), (0.40, 0.40 ± 0.05), and (0.16, 0.18 ± 0.02). The prominent factor influencing the low-frequency conductivity at different GVS densities was the extracellular volume fraction. Further studies are needed to validate the CTI method as a tool to measure the extracellular volume fractions in living tissues with different intracellular and extracellular compartments.
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Tønnesen J, Hrabĕtová S, Soria FN. Local diffusion in the extracellular space of the brain. Neurobiol Dis 2023; 177:105981. [PMID: 36581229 DOI: 10.1016/j.nbd.2022.105981] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 12/23/2022] [Accepted: 12/25/2022] [Indexed: 12/27/2022] Open
Abstract
The brain extracellular space (ECS) is a vast interstitial reticulum of extreme morphological complexity, composed of narrow gaps separated by local expansions, enabling interconnected highways between neural cells. Constituting on average 20% of brain volume, the ECS is key for intercellular communication, and understanding its diffusional properties is of paramount importance for understanding the brain. Within the ECS, neuroactive substances travel predominantly by diffusion, spreading through the interstitial fluid and the extracellular matrix scaffold after being focally released. The nanoscale dimensions of the ECS render it unresolvable by conventional live tissue compatible imaging methods, and historically diffusion of tracers has been used to indirectly infer its structure. Novel nanoscopic imaging techniques now show that the ECS is a highly dynamic compartment, and that diffusivity in the ECS is more heterogeneous than anticipated, with great variability across brain regions and physiological states. Diffusion is defined primarily by the local ECS geometry, and secondarily by the viscosity of the interstitial fluid, including the obstructive and binding properties of the extracellular matrix. ECS volume fraction and tortuosity both strongly determine diffusivity, and each can be independently regulated e.g. through alterations in glial morphology and the extracellular matrix composition. Here we aim to provide an overview of our current understanding of the ECS and its diffusional properties. We highlight emerging technological advances to respectively interrogate and model diffusion through the ECS, and point out how these may contribute in resolving the remaining enigmas of the ECS.
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Affiliation(s)
- Jan Tønnesen
- Achucarro Basque Center for Neuroscience, Leioa, Spain; Department of Neuroscience, University of the Basque Country (UPV/EHU), Leioa, Spain; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - Sabina Hrabĕtová
- Department of Cell Biology, State University of New York, Downstate Health Sciences University, Brooklyn, NY, USA; The Robert F. Furchgott Center for Neural and Behavioral Science, State University of New York Downstate Health Sciences University, Brooklyn, NY, USA
| | - Federico N Soria
- Achucarro Basque Center for Neuroscience, Leioa, Spain; Department of Neuroscience, University of the Basque Country (UPV/EHU), Leioa, Spain; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA; Centro de Investigación Biomédica en Red Enfermedades Neurodegenerativas (CIBERNED), Spain.
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Choi BK, Katoch N, Park JA, Kim JW, Oh TI, Kim HJ, Woo EJ. Measurement of extracellular volume fraction using magnetic resonance-based conductivity tensor imaging. Front Physiol 2023; 14:1132911. [PMID: 36875031 PMCID: PMC9983119 DOI: 10.3389/fphys.2023.1132911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 02/02/2023] [Indexed: 02/19/2023] Open
Abstract
Conductivity tensor imaging (CTI) using MRI is an advanced method that can non-invasively measure the electrical properties of living tissues. The contrast of CTI is based on underlying hypothesis about the proportionality between the mobility and diffusivity of ions and water molecules inside tissues. The experimental validation of CTI in both in vitro and in vivo settings is required as a reliable tool to assess tissue conditions. The changes in extracellular space can be indicators for disease progression, such as fibrosis, edema, and cell swelling. In this study, we conducted a phantom imaging experiment to test the feasibility of CTI for measuring the extracellular volume fraction in biological tissue. To mimic tissue conditions with different extracellular volume fractions, four chambers of giant vesicle suspension (GVS) with different vesicle densities were included in the phantom. The reconstructed CTI images of the phantom were compared with the separately-measured conductivity spectra of the four chambers using an impedance analyzer. Moreover, the values of the estimated extracellular volume fraction in each chamber were compared with those measured by a spectrophotometer. As the vesicle density increased, we found that the extracellular volume fraction, extracellular diffusion coefficient, and low-frequency conductivity decreased, while the intracellular diffusion coefficient slightly increased. On the other hand, the high-frequency conductivity could not clearly distinguish the four chambers. The extracellular volume fraction measured by the spectrophotometer and CTI method in each chamber were quite comparable, i.e., (1.00, 0.98 ± 0.01), (0.59, 0.63 ± 0.02), (0.40, 0.40 ± 0.05), and (0.16, 0.18 ± 0.02). The prominent factor influencing the low-frequency conductivity at different GVS densities was the extracellular volume fraction. Further studies are needed to validate the CTI method as a tool to measure the extracellular volume fractions in living tissues with different intracellular and extracellular compartments.
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Affiliation(s)
- Bup Kyung Choi
- Department of Biomedical Engineering, Kyung Hee University, Seoul, Republic of Korea
| | - Nitish Katoch
- Department of Biomedical Engineering, Kyung Hee University, Seoul, Republic of Korea
| | - Ji Ae Park
- Division of Applied RI, Korea Institute of Radiological and Medical Science, Seoul, Republic of Korea
| | - Jin Woong Kim
- Department of Radiology, Chosun University Hospital and Chosun University College of Medicine, Gwangju, Republic of Korea
| | - Tong In Oh
- Department of Biomedical Engineering, Kyung Hee University, Seoul, Republic of Korea
| | - Hyung Joong Kim
- Department of Biomedical Engineering, Kyung Hee University, Seoul, Republic of Korea
| | - Eung Je Woo
- Department of Biomedical Engineering, Kyung Hee University, Seoul, Republic of Korea
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14
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Abulikemu N, Gao X, Wang W, He Q, Wang G, Jiang T, Wang X, Cheng Y, Chen M, Li Y, Liu L, Zhao J, Li J, Jiang C, Wang Y, Han H, Wang J. Mechanism of extracellular space changes in cryptococcal brain granuloma revealed by MRI tracer. Front Neurosci 2022; 16:1034091. [PMID: 36605557 PMCID: PMC9808069 DOI: 10.3389/fnins.2022.1034091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 11/24/2022] [Indexed: 12/24/2022] Open
Abstract
Purpose This study aimed to investigate the changes in extracellular space (ECS) in cryptococcal brain granuloma and its pathological mechanism. Materials and methods The animal model of cryptococcal brain granuloma was established by injecting 1 × 106 CFU/ml of Cryptococcus neoformans type A suspension into the caudate nucleus of Sprague-Dawley rats with stereotactic technology. The infection in the brain was observed by conventional MRI scanning on days 14, 21, and 28 of modeling. The tracer-based MRI with a gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) as a magnetic tracer was performed on the rats with cryptococcal granuloma and the rats in the control group. The parameters of ECS in each area of cryptococcal brain granuloma were measured. The parameters of ECS in the two groups were compared by independent sample t-test, and the changes in ECS and its mechanism were analyzed. Results Up to 28 days of modeling, the success rate of establishing the brain cryptococcal granuloma model with 1 × 106 CFU/ml Cryptococcus neoformans suspension was 60%. In the internal area of cryptococcal granuloma, the effective diffusion coefficient D* was significantly higher than that of the control group (t = 2.76, P < 0.05), and the same trend showed in the volume ratio α (t = 3.71, P < 0.05), the clearance rate constant k (t = 3.137, P < 0.05), and the tracer half-life T1/2 (t = 3.837, P < 0.05). The tortuosity λ decreased compared with the control group (t = -2.70, P < 0.05). At the edge of the cryptococcal granuloma, the D* and α decreased, while the λ increased compared with the control group (D*:t = -6.05, P < 0.05; α: t = -4.988, P < 0.05; λ: t = 6.222, P < 0.05). Conclusion The internal area of the lesion demonstrated a quicker, broader, and more extended distribution of the tracer, while the edge of the lesion exhibited a slower and narrower distribution. MRI tracer method can monitor morphological and functional changes of ECS in pathological conditions and provide a theoretical basis for the treatment via ECS.
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Affiliation(s)
- Nuerbiyemu Abulikemu
- Imaging Center, First Affiliated Hospital of Xinjiang Medical University, Ürümqi, China,Beijing Key Laboratory of Magnetic Resonance Imaging Devices and Technology, Peking University Third Hospital, Beijing, China,Institute of Medical Technology, Peking University Health Science Center, Beijing, China
| | - Xin Gao
- Shanghai Universal Medical Imaging Diagnostic Center, Shanghai University, Shanghai, China
| | - Wei Wang
- Department of Rehabilitation Radiology, Beijing Rehabilitation Hospital, Capital Medical University, Beijing, China
| | - Qingyuan He
- Beijing Key Laboratory of Magnetic Resonance Imaging Devices and Technology, Peking University Third Hospital, Beijing, China,Institute of Medical Technology, Peking University Health Science Center, Beijing, China,Department of Radiology, Peking University Third Hospital, Beijing, China
| | - Gang Wang
- Imaging Center, First Affiliated Hospital of Xinjiang Medical University, Ürümqi, China,Imaging Center, Xi’an Gem Flower Changqing Hospital, Xi’an, China
| | - Tao Jiang
- The Animal Experimental Center, Xinjiang Medical University, Ürümqi, China
| | - Xiaodong Wang
- Department of Dermatology, First Affiliated Hospital of Xinjiang Medical University, Ürümqi, China
| | - Yumeng Cheng
- Beijing Key Laboratory of Magnetic Resonance Imaging Devices and Technology, Peking University Third Hospital, Beijing, China,Institute of Medical Technology, Peking University Health Science Center, Beijing, China
| | - Min Chen
- Department of Dermatology, Shanghai Key Laboratory of Molecular Medical Mycology, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Yanran Li
- Imaging Center, First Affiliated Hospital of Xinjiang Medical University, Ürümqi, China
| | - Lulu Liu
- Imaging Center, First Affiliated Hospital of Xinjiang Medical University, Ürümqi, China
| | - Jingjing Zhao
- Imaging Center, First Affiliated Hospital of Xinjiang Medical University, Ürümqi, China
| | - Jin Li
- Imaging Center, First Affiliated Hospital of Xinjiang Medical University, Ürümqi, China
| | - Chunhui Jiang
- Imaging Center, First Affiliated Hospital of Xinjiang Medical University, Ürümqi, China
| | - Yunling Wang
- Imaging Center, First Affiliated Hospital of Xinjiang Medical University, Ürümqi, China
| | - Hongbin Han
- Beijing Key Laboratory of Magnetic Resonance Imaging Devices and Technology, Peking University Third Hospital, Beijing, China,Institute of Medical Technology, Peking University Health Science Center, Beijing, China,Department of Radiology, Peking University Third Hospital, Beijing, China,Hongbin Han,
| | - Jian Wang
- Imaging Center, First Affiliated Hospital of Xinjiang Medical University, Ürümqi, China,Shanghai Universal Medical Imaging Diagnostic Center, Shanghai University, Shanghai, China,*Correspondence: Jian Wang,
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15
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Gu Z, Chen H, Zhao H, Yang W, Song Y, Li X, Wang Y, Du D, Liao H, Pan W, Li X, Gao Y, Han H, Tong Z. New insight into brain disease therapy: nanomedicines-crossing blood-brain barrier and extracellular space for drug delivery. Expert Opin Drug Deliv 2022; 19:1618-1635. [PMID: 36285632 DOI: 10.1080/17425247.2022.2139369] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
INTRODUCTION Brain diseases including brain tumor, Alzheimer's disease, Parkinson's disease, etc. are difficult to treat. The blood-brain barrier (BBB) is a major obstacle for drug delivery into the brain. Although nano-package and receptor-mediated delivery of nanomedicine markedly increases BBB penetration, it yet did not extensively improve clinical cure rate. Recently, brain extracellular space (ECS) and interstitial fluid (ISF) drainage in ECS have been found to determine whether a drug dissolved in ISF can reach its target cells. Notably, an increase in tortuosity of ECS associated with slower ISF drainage induced by the accumulated harmful substances, such as: amyloid-beta (Aβ), α-synuclein, and metabolic wastes, causes drug delivery failure. AREAS COVERED The methods of nano-package and receptor-mediated drug delivery and the penetration efficacy of nanomedicines across BBB and ECS are assessed. EXPERT OPINION Invasive delivering drug via ECS and noninvasive near-infrared photo-sensitive nanomedicines may provide a promising benefit to patients with brain disease.
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Affiliation(s)
- Ziqi Gu
- Key Laboratory of Alzheimer's Disease of Zhejiang Province, Institute of Aging, Oujiang Laboratory, School of Mental Health, Wenzhou Medical University, Wenzhou, China
| | - Haishu Chen
- Key Laboratory of Alzheimer's Disease of Zhejiang Province, Institute of Aging, Oujiang Laboratory, School of Mental Health, Wenzhou Medical University, Wenzhou, China
| | - Han Zhao
- Key Laboratory of Alzheimer's Disease of Zhejiang Province, Institute of Aging, Oujiang Laboratory, School of Mental Health, Wenzhou Medical University, Wenzhou, China
| | - Wanting Yang
- Key Laboratory of Alzheimer's Disease of Zhejiang Province, Institute of Aging, Oujiang Laboratory, School of Mental Health, Wenzhou Medical University, Wenzhou, China
| | - Yilan Song
- Key Laboratory of Alzheimer's Disease of Zhejiang Province, Institute of Aging, Oujiang Laboratory, School of Mental Health, Wenzhou Medical University, Wenzhou, China
| | - Xiang Li
- Key Laboratory of Alzheimer's Disease of Zhejiang Province, Institute of Aging, Oujiang Laboratory, School of Mental Health, Wenzhou Medical University, Wenzhou, China
| | - Yang Wang
- Institute of Medical Technology, Peking University Health Science Center, Beijing, China.,Department of Radiology, Peking University Third Hospital, Beijing, China
| | - Dan Du
- Department of Radiology, Peking University Third Hospital, Beijing, China.,Department of Magnetic Resonance Imaging, Qinhuangdao Municipal No. 1 Hospital, Qinhuangdao, China.,Beijing Key Laboratory of Magnetic Resonance Imaging Devices and Technology, Peking University Third Hospital, Beijing, China
| | - Haikang Liao
- Key Laboratory of Alzheimer's Disease of Zhejiang Province, Institute of Aging, Oujiang Laboratory, School of Mental Health, Wenzhou Medical University, Wenzhou, China
| | - Wenhao Pan
- Key Laboratory of Alzheimer's Disease of Zhejiang Province, Institute of Aging, Oujiang Laboratory, School of Mental Health, Wenzhou Medical University, Wenzhou, China
| | - Xi Li
- The Affiliated Kangning Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yajuan Gao
- Department of Radiology, Peking University Third Hospital, Beijing, China.,NMPA key Laboratory for Evaluation of Medical Imaging Equipment and Technique, Beijing, China
| | - Hongbin Han
- Institute of Medical Technology, Peking University Health Science Center, Beijing, China.,Department of Radiology, Peking University Third Hospital, Beijing, China.,Beijing Key Laboratory of Magnetic Resonance Imaging Devices and Technology, Peking University Third Hospital, Beijing, China.,Peking University Shenzhen Graduate School, Shenzhen, China
| | - Zhiqian Tong
- Key Laboratory of Alzheimer's Disease of Zhejiang Province, Institute of Aging, Oujiang Laboratory, School of Mental Health, Wenzhou Medical University, Wenzhou, China.,The Affiliated Kangning Hospital of Wenzhou Medical University, Wenzhou, China
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16
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Transport in the Brain Extracellular Space: Diffusion, but Which Kind? Int J Mol Sci 2022; 23:ijms232012401. [PMID: 36293258 PMCID: PMC9604357 DOI: 10.3390/ijms232012401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 10/10/2022] [Accepted: 10/12/2022] [Indexed: 11/17/2022] Open
Abstract
The mechanisms of transport of substances in the brain parenchyma have been a hot topic in scientific discussion in the past decade. This discussion was triggered by the proposed glymphatic hypothesis, which assumes a directed flow of cerebral fluid within the parenchyma, in contrast to the previous notion that diffusion is the main mechanism. However, when discussing the issue of “diffusion or non-diffusion”, much less attention was given to the question that diffusion itself can have a different character. In our opinion, some of the recently published results do not fit into the traditional understanding of diffusion. In this regard, we outline the relevant new theoretical approaches on transport processes in complex random media such as concepts of diffusive diffusivity and time-dependent homogenization, which expands the understanding of the forms of transport of substances based on diffusion.
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17
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Cifuentes A, Trägårdh J. A method for single particle tracking through a multimode fiber. OPTICS EXPRESS 2022; 30:36055-36064. [PMID: 36258542 DOI: 10.1364/oe.470111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Accepted: 08/27/2022] [Indexed: 06/16/2023]
Abstract
Multimode optical fiber (MMF) endoscopes have recently gained widespread attention as a novel tool for imaging deep within tissue using light microscopy. We here present a method for particle tracking through the MMF, which overcomes the lack of a fast enough wide-field fluorescence imaging modality for this type of endoscope, namely a discrete implementation of orbital particle tracking. We achieve biologically relevant tracking speeds (up to 1.2 μm/s) despite using a slow SLM for the wavefront shaping. We demonstrate a tracking accuracy of λ/50 for a 0.3 NA fiber and show tracking of a pinhole moving to mimic Brownian motion with diffusion rates of up to 0.3 μm2/s.
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18
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Abstract
We review theoretical and numerical models of the glymphatic system, which circulates cerebrospinal fluid and interstitial fluid around the brain, facilitating solute transport. Models enable hypothesis development and predictions of transport, with clinical applications including drug delivery, stroke, cardiac arrest, and neurodegenerative disorders like Alzheimer’s disease. We sort existing models into broad categories by anatomical function: Perivascular flow, transport in brain parenchyma, interfaces to perivascular spaces, efflux routes, and links to neuronal activity. Needs and opportunities for future work are highlighted wherever possible; new models, expanded models, and novel experiments to inform models could all have tremendous value for advancing the field.
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19
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Xu X, Ge X, Xiong H, Qin Z. Toward dynamic, anisotropic, high-resolution, and functional measurement in the brain extracellular space. NEUROPHOTONICS 2022; 9:032210. [PMID: 35573823 PMCID: PMC9094757 DOI: 10.1117/1.nph.9.3.032210] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Accepted: 03/31/2022] [Indexed: 06/15/2023]
Abstract
Diffusion of substances in the brain extracellular space (ECS) is important for extrasynaptic communication, extracellular ionic homeostasis, drug delivery, and metabolic waste clearance. However, substance diffusion is largely constrained by the geometry of brain ECS and the extracellular matrix. Investigating the diffusion properties of substances not only reveals the structural information of the brain ECS but also advances the understanding of intercellular signaling of brain cells. Among different techniques for substance diffusion measurement, the optical imaging method is sensitive and straightforward for measuring the dynamics and distribution of fluorescent molecules or sensors and has been used for molecular diffusion measurement in the brain. We mainly discuss recent advances of optical imaging-enabled measurements toward dynamic, anisotropic, high-resolution, and functional aspects of the brain ECS diffusion within the last 5 to 10 years. These developments are made possible by advanced imaging, such as light-sheet microscopy and single-particle tracking in tissue, and new fluorescent biosensors for neurotransmitters. We envision future efforts to map the ECS diffusivity across the brain under healthy and diseased conditions to guide the therapeutic delivery and better understand neurochemical transmissions that are relevant to physiological signaling and functions in brain circuits.
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Affiliation(s)
- Xueqi Xu
- University of Texas at Dallas, Department of Mechanical Engineering, Richardson, Texas, United States
| | - Xiaoqian Ge
- University of Texas at Dallas, Department of Mechanical Engineering, Richardson, Texas, United States
| | - Hejian Xiong
- University of Texas at Dallas, Department of Mechanical Engineering, Richardson, Texas, United States
| | - Zhenpeng Qin
- University of Texas at Dallas, Department of Mechanical Engineering, Richardson, Texas, United States
- University of Texas at Dallas, Department of Bioengineering, Richardson, Texas, United States
- University of Texas at Southwestern Medical Center, Department of Surgery, Richardson, Texas, United States
- University of Texas at Dallas, The Center for Advanced Pain Studies, Richardson, Texas, United States
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20
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McKenna M, Filteau JR, Butler B, Sluis K, Chungyoun M, Schimek N, Nance E. Organotypic whole hemisphere brain slice models to study the effects of donor age and oxygen-glucose-deprivation on the extracellular properties of cortical and striatal tissue. J Biol Eng 2022; 16:14. [PMID: 35698088 PMCID: PMC9195469 DOI: 10.1186/s13036-022-00293-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 05/21/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The brain extracellular environment is involved in many critical processes associated with neurodevelopment, neural function, and repair following injury. Organization of the extracellular matrix and properties of the extracellular space vary throughout development and across different brain regions, motivating the need for platforms that provide access to multiple brain regions at different stages of development. We demonstrate the utility of organotypic whole hemisphere brain slices as a platform to probe regional and developmental changes in the brain extracellular environment. We also leverage whole hemisphere brain slices to characterize the impact of cerebral ischemia on different regions of brain tissue. RESULTS Whole hemisphere brain slices taken from postnatal (P) day 10 and P17 rats retained viable, metabolically active cells through 14 days in vitro (DIV). Oxygen-glucose-deprivation (OGD), used to model a cerebral ischemic event in vivo, resulted in reduced slice metabolic activity and elevated cell death, regardless of slice age. Slices from P10 and P17 brains showed an oligodendrocyte and microglia-driven proliferative response after OGD exposure, higher than the proliferative response seen in DIV-matched normal control slices. Multiple particle tracking in oxygen-glucose-deprived brain slices revealed that oxygen-glucose-deprivation impacts the extracellular environment of brain tissue differently depending on brain age and brain region. In most instances, the extracellular space was most difficult to navigate immediately following insult, then gradually provided less hindrance to extracellular nanoparticle diffusion as time progressed. However, changes in diffusion were not universal across all brain regions and ages. CONCLUSIONS We demonstrate whole hemisphere brain slices from P10 and P17 rats can be cultured up to two weeks in vitro. These brain slices provide a viable platform for studying both normal physiological processes and injury associated mechanisms with control over brain age and region. Ex vivo OGD impacted cortical and striatal brain tissue differently, aligning with preexisting data generated in in vivo models. These data motivate the need to account for both brain region and age when investigating mechanisms of injury and designing potential therapies for cerebral ischemia.
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Affiliation(s)
- Michael McKenna
- Department of Chemical Engineering, University of Washington, 105 Benson Hall, Box 351750, Seattle, WA, 98195-1750, USA
| | - Jeremy R Filteau
- Department of Chemical Engineering, University of Washington, 105 Benson Hall, Box 351750, Seattle, WA, 98195-1750, USA
| | - Brendan Butler
- Department of Chemical Engineering, University of Washington, 105 Benson Hall, Box 351750, Seattle, WA, 98195-1750, USA
| | - Kenneth Sluis
- Department of Chemical Engineering, University of Washington, 105 Benson Hall, Box 351750, Seattle, WA, 98195-1750, USA
| | - Michael Chungyoun
- Department of Chemical Engineering, University of Washington, 105 Benson Hall, Box 351750, Seattle, WA, 98195-1750, USA
| | - Nels Schimek
- Department of Chemistry, University of Washington, Seattle, WA, USA
| | - Elizabeth Nance
- Department of Chemical Engineering, University of Washington, 105 Benson Hall, Box 351750, Seattle, WA, 98195-1750, USA. .,e-Science Institute, University of Washington, Seattle, WA, USA. .,Department of Bioengineering, University of Washington, Seattle, WA, USA.
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21
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Chen X, Fan X, Song X, Gardner M, Du F, Öngür D. White Matter Metabolite Relaxation and Diffusion Abnormalities in First-Episode Psychosis: A Longitudinal Study. Schizophr Bull 2022; 48:712-720. [PMID: 34999898 PMCID: PMC9077413 DOI: 10.1093/schbul/sbab149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Microstructural abnormalities in the white matter (WM) are implicated in the pathophysiology of psychosis. In vivo magnetic resonance spectroscopy (MRS) can probe the brain's intracellular microenvironment through the measurement of transverse relaxation and diffusion of neurometabolites and possibly provide cell-specific information. In our previous studies, we observed differential metabolite signal abnormalities in first episode and chronic stages of psychosis. In the present work, longitudinal data were presented for the first time on white matter cell-type specific abnormalities using a combination of diffusion tensor spectroscopy (DTS), T2 MRS, and diffusion tensor imaging (DTI) from a group of 25 first episode psychosis patients and nine matched controls scanned at baseline and one and two years of follow-up. We observed significantly reduced choline ADC in the year 1 of follow-up (0.194 µm2/ms) compared to baseline (0.229 µm2/ms), followed by a significant increase in NAA ADC in the year 2 follow-up (0.258 µm2/ms) from baseline (0.222 µm2/ms) and year 1 follow-up (0.217 µm2/ms). In contrast, NAA T2 relaxation, reflecting a related but different aspect of microenvironment from diffusion, was reduced at year 1 follow-up (257 ms) compared to baseline (278 ms). These abnormalities were observed in the absence of any abnormalities in water relaxation and diffusion at any timepoint. These findings indicate that abnormalities are seen in in glial-enriched (choline) signals in early stages of psychosis, followed by the subsequent emergence of neuronal-enriched (NAA) diffusion abnormalities, all in the absence of nonspecific water signal abnormalities.
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Affiliation(s)
- Xi Chen
- Psychotic Disorders Division, McLean Hospital, Belmont, MA, USA,McLean Imaging Center, McLean Hospital, Belmont, MA, USA,Department of Psychiatry, Harvard Medical School, Boston, MA, USA
| | - Xiaoying Fan
- Psychotic Disorders Division, McLean Hospital, Belmont, MA, USA,McLean Imaging Center, McLean Hospital, Belmont, MA, USA
| | - Xiaopeng Song
- Psychotic Disorders Division, McLean Hospital, Belmont, MA, USA,McLean Imaging Center, McLean Hospital, Belmont, MA, USA,Department of Psychiatry, Harvard Medical School, Boston, MA, USA
| | - Margaret Gardner
- Psychotic Disorders Division, McLean Hospital, Belmont, MA, USA,McLean Imaging Center, McLean Hospital, Belmont, MA, USA
| | - Fei Du
- Psychotic Disorders Division, McLean Hospital, Belmont, MA, USA,McLean Imaging Center, McLean Hospital, Belmont, MA, USA,Department of Psychiatry, Harvard Medical School, Boston, MA, USA
| | - Dost Öngür
- To whom correspondence should be addressed; Psychotic Disorders Division, McLean Hospital, AB3 South 342. 115 Mill St., Belmont, MA 02478, USA; tel: 617-855-2779, fax: 617-855-2895, e-mail:
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22
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Sharon A, Shmoel N, Erez H, Jankowski MM, Friedmann Y, Spira ME. Ultrastructural Analysis of Neuroimplant-Parenchyma Interfaces Uncover Remarkable Neuroregeneration Along-With Barriers That Limit the Implant Electrophysiological Functions. Front Neurosci 2021; 15:764448. [PMID: 34880722 PMCID: PMC8645653 DOI: 10.3389/fnins.2021.764448] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/21/2021] [Indexed: 12/13/2022] Open
Abstract
Despite increasing use of in vivo multielectrode array (MEA) implants for basic research and medical applications, the critical structural interfaces formed between the implants and the brain parenchyma, remain elusive. Prevailing view assumes that formation of multicellular inflammatory encapsulating-scar around the implants [the foreign body response (FBR)] degrades the implant electrophysiological functions. Using gold mushroom shaped microelectrodes (gMμEs) based perforated polyimide MEA platforms (PPMPs) that in contrast to standard probes can be thin sectioned along with the interfacing parenchyma; we examined here for the first time the interfaces formed between brains parenchyma and implanted 3D vertical microelectrode platforms at the ultrastructural level. Our study demonstrates remarkable regenerative processes including neuritogenesis, axon myelination, synapse formation and capillaries regrowth in contact and around the implant. In parallel, we document that individual microglia adhere tightly and engulf the gMμEs. Modeling of the formed microglia-electrode junctions suggest that this configuration suffice to account for the low and deteriorating recording qualities of in vivo MEA implants. These observations help define the anticipated hurdles to adapting the advantageous 3D in vitro vertical-electrode technologies to in vivo settings, and suggest that improving the recording qualities and durability of planar or 3D in vivo electrode implants will require developing approaches to eliminate the insulating microglia junctions.
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Affiliation(s)
- Aviv Sharon
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Charles E. Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Nava Shmoel
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Harvey M. Kruger Family Center for Nanoscience, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Hadas Erez
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Charles E. Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Maciej M. Jankowski
- The Charles E. Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Hebrew University of Jerusalem, Jerusalem, Israel
- Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Yael Friedmann
- Bio-Imaging Unit, The Alexander Silberman Institute of Life Science the Hebrew University of Jerusalem, Jerusalem, Israel
| | - Micha E. Spira
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Charles E. Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Harvey M. Kruger Family Center for Nanoscience, The Hebrew University of Jerusalem, Jerusalem, Israel
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23
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Yoshida S, Kisley L. Super-resolution fluorescence imaging of extracellular environments. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 257:119767. [PMID: 33862370 DOI: 10.1016/j.saa.2021.119767] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 03/24/2021] [Accepted: 03/28/2021] [Indexed: 06/12/2023]
Abstract
The extracellular matrix (ECM) is an important biophysical environment that plays a role in a number of physiological processes. The ECM is highly dynamic, with changes occurring as local, nanoscale, physicochemical variations in physical confinement and chemistry from the perspective of biological molecules. The length and time scale of ECM dynamics are challenging to measure with current spectroscopic techniques. Super-resolution fluorescence microscopy has the potential to probe local, nanoscale, physicochemical variations in the ECM. Here, we review super-resolution imaging and analysis methods and their application to study model nanoparticles and biomolecules within synthetic ECM hydrogels and the brain extracellular space (ECS). We provide a perspective of future directions for the field that can move super-resolution imaging of the ECM towards more biomedically-relevant samples. Overall, super-resolution imaging is a powerful tool that can increase our understanding of extracellular environments at new spatiotemporal scales to reveal ECM processes at the molecular-level.
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Affiliation(s)
- Shawn Yoshida
- Department of Physics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Lydia Kisley
- Department of Physics, Case Western Reserve University, Cleveland, OH 44106, USA; Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA.
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Calovi S, Soria FN, Tønnesen J. Super-resolution STED microscopy in live brain tissue. Neurobiol Dis 2021; 156:105420. [PMID: 34102277 DOI: 10.1016/j.nbd.2021.105420] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 06/03/2021] [Accepted: 06/04/2021] [Indexed: 12/25/2022] Open
Abstract
STED microscopy is one of several fluorescence microscopy techniques that permit imaging at higher spatial resolution than what the diffraction-limit of light dictates. STED imaging is unique among these super-resolution modalities in being a beam-scanning microscopy technique based on confocal or 2-photon imaging, which provides the advantage of superior optical sectioning in thick samples. Compared to the other super-resolution techniques that are based on widefield microscopy, this makes STED particularly suited for imaging inside live brain tissue, such as in slices or in vivo. Notably, the 50 nm resolution provided by STED microscopy enables analysis of neural morphologies that conventional confocal and 2-photon microscopy approaches cannot resolve, including all-important synaptic structures. Over the course of the last 20 years, STED microscopy has undergone extensive developments towards ever more versatile use, and has facilitated remarkable neurophysiological discoveries. The technique is still not widely adopted for live tissue imaging, even though one of its particular strengths is exactly in resolving the nanoscale dynamics of synaptic structures in brain tissue, as well as in addressing the complex morphologies of glial cells, and revealing the intricate structure of the brain extracellular space. Not least, live tissue STED microscopy has so far hardly been applied in settings of pathophysiology, though also here it shows great promise for providing new insights. This review outlines the technical advantages of STED microscopy for imaging in live brain tissue, and highlights key neurobiological findings brought about by the technique.
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Affiliation(s)
- Stefano Calovi
- Laboratory of Molecular Pharmacology, Institute of Experimental Medicine, Budapest, Hungary; János Szentágothai Doctoral School, Semmelweis University, Budapest, Hungary; Achucarro Basque Center for Neuroscience, Leioa, Spain
| | - Federico N Soria
- Achucarro Basque Center for Neuroscience, Leioa, Spain; Department of Neuroscience, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Jan Tønnesen
- Achucarro Basque Center for Neuroscience, Leioa, Spain; Department of Neuroscience, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), Leioa, Spain.
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Paviolo C, Cognet L. Near-infrared nanoscopy with carbon-based nanoparticles for the exploration of the brain extracellular space. Neurobiol Dis 2021; 153:105328. [PMID: 33713842 DOI: 10.1016/j.nbd.2021.105328] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 03/04/2021] [Accepted: 03/06/2021] [Indexed: 12/19/2022] Open
Abstract
Understanding the physiology and pathology of the brain requires detailed knowledge of its complex structures as well as dynamic internal processes at very different scales from the macro down to the molecular dimensions. A major yet poorly described brain compartment is the brain extracellular space (ECS). Signalling molecules rapidly diffuse through the brain ECS which is complex and dynamic structure at numerous lengths and time scales. In recent years, characterization of the ECS using nanomaterials has made remarkable progress, including local analysis of nanoscopic dimensions and diffusivity as well as local chemical sensing. In particular, carbon nanomaterials combined with advanced optical technologies, biochemical and biophysical analysis, offer novel promises for understanding the ECS morphology as well as neuron connectivity and neurochemistry. In this review, we present the state-of-the-art in this quest, which mainly focuses on a type of carbon nanomaterial, single walled carbon nanotubes, as fluorescent nanoprobes to unveil the ECS features in the nanometre domain.
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Affiliation(s)
- Chiara Paviolo
- LP2N, Institut d'Optique Graduate School, CNRS, Université de Bordeaux, 33400 Talence, France
| | - Laurent Cognet
- LP2N, Institut d'Optique Graduate School, CNRS, Université de Bordeaux, 33400 Talence, France.
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Nahirney PC, Tremblay ME. Brain Ultrastructure: Putting the Pieces Together. Front Cell Dev Biol 2021; 9:629503. [PMID: 33681208 PMCID: PMC7930431 DOI: 10.3389/fcell.2021.629503] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 01/20/2021] [Indexed: 12/11/2022] Open
Abstract
Unraveling the fine structure of the brain is important to provide a better understanding of its normal and abnormal functioning. Application of high-resolution electron microscopic techniques gives us an unprecedented opportunity to discern details of the brain parenchyma at nanoscale resolution, although identifying different cell types and their unique features in two-dimensional, or three-dimensional images, remains a challenge even to experts in the field. This article provides insights into how to identify the different cell types in the central nervous system, based on nuclear and cytoplasmic features, amongst other unique characteristics. From the basic distinction between neurons and their supporting cells, the glia, to differences in their subcellular compartments, organelles and their interactions, ultrastructural analyses can provide unique insights into the changes in brain function during aging and disease conditions, such as stroke, neurodegeneration, infection and trauma. Brain parenchyma is composed of a dense mixture of neuronal and glial cell bodies, together with their intertwined processes. Intracellular components that vary between cells, and can become altered with aging or disease, relate to the cytoplasmic and nucleoplasmic density, nuclear heterochromatin pattern, mitochondria, endoplasmic reticulum and Golgi complex, lysosomes, neurosecretory vesicles, and cytoskeletal elements (actin, intermediate filaments, and microtubules). Applying immunolabeling techniques to visualize membrane-bound or intracellular proteins in neurons and glial cells gives an even better appreciation of the subtle differences unique to these cells across contexts of health and disease. Together, our observations reveal how simple ultrastructural features can be used to identify specific changes in cell types, their health status, and functional relationships in the brain.
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Abstract
Unraveling the fine structure of the brain is important to provide a better understanding of its normal and abnormal functioning. Application of high-resolution electron microscopic techniques gives us an unprecedented opportunity to discern details of the brain parenchyma at nanoscale resolution, although identifying different cell types and their unique features in two-dimensional, or three-dimensional images, remains a challenge even to experts in the field. This article provides insights into how to identify the different cell types in the central nervous system, based on nuclear and cytoplasmic features, amongst other unique characteristics. From the basic distinction between neurons and their supporting cells, the glia, to differences in their subcellular compartments, organelles and their interactions, ultrastructural analyses can provide unique insights into the changes in brain function during aging and disease conditions, such as stroke, neurodegeneration, infection and trauma. Brain parenchyma is composed of a dense mixture of neuronal and glial cell bodies, together with their intertwined processes. Intracellular components that vary between cells, and can become altered with aging or disease, relate to the cytoplasmic and nucleoplasmic density, nuclear heterochromatin pattern, mitochondria, endoplasmic reticulum and Golgi complex, lysosomes, neurosecretory vesicles, and cytoskeletal elements (actin, intermediate filaments, and microtubules). Applying immunolabeling techniques to visualize membrane-bound or intracellular proteins in neurons and glial cells gives an even better appreciation of the subtle differences unique to these cells across contexts of health and disease. Together, our observations reveal how simple ultrastructural features can be used to identify specific changes in cell types, their health status, and functional relationships in the brain.
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Affiliation(s)
- Patrick C Nahirney
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | - Marie-Eve Tremblay
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
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