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Potential of Multiscale Astrocyte Imaging for Revealing Mechanisms Underlying Neurodevelopmental Disorders. Int J Mol Sci 2021; 22:ijms221910312. [PMID: 34638653 PMCID: PMC8508625 DOI: 10.3390/ijms221910312] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 09/21/2021] [Accepted: 09/22/2021] [Indexed: 01/18/2023] Open
Abstract
Astrocytes provide trophic and metabolic support to neurons and modulate circuit formation during development. In addition, astrocytes help maintain neuronal homeostasis through neurovascular coupling, blood-brain barrier maintenance, clearance of metabolites and nonfunctional proteins via the glymphatic system, extracellular potassium buffering, and regulation of synaptic activity. Thus, astrocyte dysfunction may contribute to a myriad of neurological disorders. Indeed, astrocyte dysfunction during development has been implicated in Rett disease, Alexander's disease, epilepsy, and autism, among other disorders. Numerous disease model mice have been established to investigate these diseases, but important preclinical findings on etiology and pathophysiology have not translated into clinical interventions. A multidisciplinary approach is required to elucidate the mechanism of these diseases because astrocyte dysfunction can result in altered neuronal connectivity, morphology, and activity. Recent progress in neuroimaging techniques has enabled noninvasive investigations of brain structure and function at multiple spatiotemporal scales, and these technologies are expected to facilitate the translation of preclinical findings to clinical studies and ultimately to clinical trials. Here, we review recent progress on astrocyte contributions to neurodevelopmental and neuropsychiatric disorders revealed using novel imaging techniques, from microscopy scale to mesoscopic scale.
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Petrus E, Saar G, Daoust A, Dodd S, Koretsky AP. A hierarchy of manganese competition and entry in organotypic hippocampal slice cultures. NMR IN BIOMEDICINE 2021; 34:e4476. [PMID: 33538073 PMCID: PMC7988546 DOI: 10.1002/nbm.4476] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 01/02/2021] [Indexed: 05/15/2023]
Abstract
Contrast agents improve clinical and basic research MRI. The manganese ion (Mn2+ ) is an essential, endogenous metal found in cells and it enhances MRI contrast because of its paramagnetic properties. Manganese-enhanced MRI (MEMRI) has been widely used to image healthy and diseased states of the body and the brain in a variety of animal models. There has also been some work in translating the useful properties of MEMRI to humans. Mn2+ accumulates in brain regions with high neural activity and enters cells via voltage-dependent channels that flux calcium (Ca2+ ). In addition, metal transporters for zinc (Zn2+ ) and iron (Fe2+ ) can also transport Mn2+ . There is also transfer through channels specific for Mn2+ . Although Mn2+ accumulates in many tissues including brain, the mechanisms and preferences of its mode of entry into cells are not well characterized. The current study used MRI on living organotypic hippocampal slice cultures to detect which transport mechanisms are preferentially used by Mn2+ to enter cells. The use of slice culture overcomes the presence of the blood brain barrier, which limits inferences made with studies of the intact brain in vivo. A range of Mn2+ concentrations were used and their effects on neural activity were assessed to avoid using interfering doses of Mn2+ . Zn2+ and Fe2+ were the most efficient competitors for Mn2+ uptake into the cultured slices, while the presence of Ca2+ or Ca2+ channel antagonists had a more moderate effect. Reducing slice activity via excitatory receptor antagonists was also effective at lowering Mn2+ uptake. In conclusion, a hierarchy of those agents which influence Mn2+ uptake was established to enhance understanding of how Mn2+ enters cells in a cultured slice preparation.
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Affiliation(s)
- Emily Petrus
- Laboratory of Functional and Molecular ImagingNational Institute of Neurological Disorders and Stroke, National Institutes of HealthBethesdaMarylandUSA
| | - Galit Saar
- Laboratory of Functional and Molecular ImagingNational Institute of Neurological Disorders and Stroke, National Institutes of HealthBethesdaMarylandUSA
| | - Alexia Daoust
- Laboratory of Functional and Molecular ImagingNational Institute of Neurological Disorders and Stroke, National Institutes of HealthBethesdaMarylandUSA
| | - Steve Dodd
- Laboratory of Functional and Molecular ImagingNational Institute of Neurological Disorders and Stroke, National Institutes of HealthBethesdaMarylandUSA
| | - Alan P. Koretsky
- Laboratory of Functional and Molecular ImagingNational Institute of Neurological Disorders and Stroke, National Institutes of HealthBethesdaMarylandUSA
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MnDPDP: Contrast Agent for Imaging and Protection of Viable Tissue. CONTRAST MEDIA & MOLECULAR IMAGING 2020; 2020:3262835. [PMID: 32994754 PMCID: PMC7501573 DOI: 10.1155/2020/3262835] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 05/12/2020] [Indexed: 01/22/2023]
Abstract
The semistable chelate manganese (Mn) dipyridoxyl diphosphate (MnDPDP, mangafodipir), previously used as an intravenous (i.v.) contrast agent (Teslascan™, GE Healthcare) for Mn-ion-enhanced MRI (MEMRI), should be reappraised for clinical use but now as a diagnostic drug with cytoprotective properties. Approved for imaging of the liver and pancreas, MnDPDP enhances contrast also in other targets such as the heart, kidney, glandular tissue, and potentially retina and brain. Transmetallation releases paramagnetic Mn2+ for cellular uptake in competition with calcium (Ca2+), and intracellular (IC) macromolecular Mn2+ adducts lower myocardial T1 to midway between native values and values obtained with gadolinium (Gd3+). What is essential is that T1 mapping and, to a lesser degree, T1 weighted imaging enable quantification of viability at a cellular or even molecular level. IC Mn2+ retention for hours provides delayed imaging as another advantage. Examples in humans include quantitative imaging of cardiomyocyte remodeling and of Ca2+ channel activity, capabilities beyond the scope of Gd3+ based or native MRI. In addition, MnDPDP and the metabolite Mn dipyridoxyl diethyl-diamine (MnPLED) act as catalytic antioxidants enabling prevention and treatment of oxidative stress caused by tissue injury and inflammation. Tested applications in humans include protection of normal cells during chemotherapy of cancer and, potentially, of ischemic tissues during reperfusion. Theragnostic use combining therapy with delayed imaging remains to be explored. This review updates MnDPDP and its clinical potential with emphasis on the working mode of an exquisite chelate in the diagnosis of heart disease and in the treatment of oxidative stress.
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Droguerre M, Tsurugizawa T, Duchêne A, Portal B, Guiard BP, Déglon N, Rouach N, Hamon M, Mouthon F, Ciobanu L, Charvériat M. A New Tool for In Vivo Study of Astrocyte Connexin 43 in Brain. Sci Rep 2019; 9:18292. [PMID: 31797899 PMCID: PMC6892890 DOI: 10.1038/s41598-019-54858-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 11/20/2019] [Indexed: 01/22/2023] Open
Abstract
Astrocytes are glial cells organized in dynamic and structured networks in the brain. These plastic networks, involving key proteins such as connexin 43 (Cx43), are engaged in fine neuronal tuning and have recently been considered as emerging therapeutic targets in central nervous system disorders. We developed and validated a new application of the manganese-enhanced magnetic resonance imaging (MEMRI) technique allowing in vivo investigations of astrocyte-neuron interactions through quantification of brain Cx43 functional activity. The proof of concept has been achieved by quantification of MEMRI signals in brain after either local astrocyte-specific Cx43 knockdown with shRNA or systemic administration of Cx43 blockers. Unilateral hippocampal Cx43 genetical silencing was associated with an ipsilateral local increase of MEMRI signal. Furthermore, Cx43 blockers also enhanced MEMRI signal responses in hippocampus. Altogether, these data reveal the MEMRI technique as a tool for quantitative imaging of in vivo Cx43-dependent function in astrocytes under physiological and pathological conditions.
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Affiliation(s)
| | | | | | - Benjamin Portal
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31330, Toulouse, France
| | - Bruno P Guiard
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31330, Toulouse, France
| | - Nicole Déglon
- Laboratory of Neurotherapies and NeuroModulation, Neuroscience research Center (CRN), Lausanne University Hospital (CHUV) and University of Lausanne, 1011, Lausanne, Switzerland.,Laboratory of Neurotherapies and NeuroModulation, Department of Clinical Neuroscience (DNC), Lausanne University Hospital (CHUV) and University of Lausanne, 1011, Lausanne, Switzerland
| | - Nathalie Rouach
- Laboratory of Neuroglial Interactions in Cerebral Physiopathology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, 75005, France
| | - Michel Hamon
- Theranexus, 60 Avenue Rockefeller, 69008, Lyon, France
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Wang X, Xu L, Ren Z, Fan M, Zhang J, Qi H, Xu M. A novel manganese chelated macromolecular MRI contrast agent based on O-carboxymethyl chitosan derivatives. Colloids Surf B Biointerfaces 2019; 183:110452. [PMID: 31473409 DOI: 10.1016/j.colsurfb.2019.110452] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 08/05/2019] [Accepted: 08/21/2019] [Indexed: 12/21/2022]
Abstract
Currently used Gd-based and Mn-based small molecular MRI contrast agents fail to meet the requirements for the long-term monitoring, and the potential safety risk under high administration dose or repeat dosing needs to be considered. In the present study, a biocompatible macromolecular magnetic resonance imaging (MRI) contrast agents based on O-carboxymethyl chitosan (CMCS), CMCS-(Mn-DTPA)n was designed and synthesized. The relaxivity of CMCS-(Mn-DTPA)n is approximately 3.5 and 5.5 times higher than that of Gd-DTPA and Mn-DPDP in aqueous solution, respectively. The MRI signal intensity in the kidney and liver of Sprague Dawley (SD) rats is significantly increased at a dose of 0.03 mM Mn/kg b.w. CMCS-(Mn-DTPA)n accompanied by a long effective imaging window. According to in vitro studies, CMCS-(Mn-DTPA)n exhibits good cellular and blood biocompatibility at the dose necessary for MRI imaging. Based on the results from in vivo studies, manganese (Mn) is completely excreted from SD rats within ten days after administration and does not exert a pathological effect on the liver. CMCS-(Mn-DTPA)n represents a potentially novel MRI contrast agent due to its excellent relaxivity, long effective imaging window and good biocompatibility.
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Affiliation(s)
- Xianghui Wang
- Shanghai Key Laboratory of Magnetic Resonance & Biophysics Lab, School of Physics and Materials Science, East China Normal University, Shanghai, 200062, China
| | - Li Xu
- Shanghai Key Laboratory of Magnetic Resonance & Biophysics Lab, School of Physics and Materials Science, East China Normal University, Shanghai, 200062, China; School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Zhanying Ren
- Shanghai Key Laboratory of Magnetic Resonance & Biophysics Lab, School of Physics and Materials Science, East China Normal University, Shanghai, 200062, China
| | - Mingxia Fan
- Shanghai Key Laboratory of Magnetic Resonance & Biophysics Lab, School of Physics and Materials Science, East China Normal University, Shanghai, 200062, China
| | - Jie Zhang
- Shanghai Key Laboratory of Magnetic Resonance & Biophysics Lab, School of Physics and Materials Science, East China Normal University, Shanghai, 200062, China
| | - Hongxin Qi
- Shanghai Key Laboratory of Magnetic Resonance & Biophysics Lab, School of Physics and Materials Science, East China Normal University, Shanghai, 200062, China
| | - Min Xu
- Shanghai Key Laboratory of Magnetic Resonance & Biophysics Lab, School of Physics and Materials Science, East China Normal University, Shanghai, 200062, China.
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