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Beinlich FRM, Asiminas A, Untiet V, Bojarowska Z, Plá V, Sigurdsson B, Timmel V, Gehrig L, Graber MH, Hirase H, Nedergaard M. Oxygen imaging of hypoxic pockets in the mouse cerebral cortex. Science 2024; 383:1471-1478. [PMID: 38547288 DOI: 10.1126/science.adn1011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 02/23/2024] [Indexed: 04/02/2024]
Abstract
Consciousness is lost within seconds upon cessation of cerebral blood flow. The brain cannot store oxygen, and interruption of oxidative phosphorylation is fatal within minutes. Yet only rudimentary knowledge exists regarding cortical partial oxygen tension (Po2) dynamics under physiological conditions. Here we introduce Green enhanced Nano-lantern (GeNL), a genetically encoded bioluminescent oxygen indicator for Po2 imaging. In awake behaving mice, we uncover the existence of spontaneous, spatially defined "hypoxic pockets" and demonstrate their linkage to the abrogation of local capillary flow. Exercise reduced the burden of hypoxic pockets by 52% compared with rest. The study provides insight into cortical oxygen dynamics in awake behaving animals and concurrently establishes a tool to delineate the importance of oxygen tension in physiological processes and neurological diseases.
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Affiliation(s)
- Felix R M Beinlich
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Antonios Asiminas
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Verena Untiet
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Zuzanna Bojarowska
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Virginia Plá
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Björn Sigurdsson
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Vincenzo Timmel
- School of Engineering, FHNW University of Applied Sciences and Arts Northwestern Switzerland, 5210 Windisch, Switzerland
| | - Lukas Gehrig
- School of Engineering, FHNW University of Applied Sciences and Arts Northwestern Switzerland, 5210 Windisch, Switzerland
| | - Michael H Graber
- School of Engineering, FHNW University of Applied Sciences and Arts Northwestern Switzerland, 5210 Windisch, Switzerland
| | - Hajime Hirase
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Maiken Nedergaard
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY 14642, USA
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2
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Abstract
The timing of life on Earth is remarkable: between individuals of the same species, a highly similar temporal pattern is observed, with shared periods of activity and inactivity each day. At the individual level, this means that over the course of a single day, a person alternates between two states. They are either upright, active, and communicative or they lie down in a state of (un)consciousness called sleep where even the characteristic of neuronal signals in the brain shows distinctive properties. The circadian clock governs both of these time stamps-activity and (apparent) inactivity-making them come and go consistently at the same approximate time each day. This behavior thus represents the meeting of two pervasive systems: the circadian clock and metabolism. In this article, we will describe what is known about how the circadian clock anticipates daily changes in oxygen usage, how circadian clock regulation may relate to normal physiology, and to hypoxia and ischemia that can result from pathologies such as myocardial infarction and stroke.
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Affiliation(s)
- Francesca Sartor
- Institute of Medical Psychology, Medical Faculty, LMU Munich, Germany (F.S., B.F.-B., M.M.)
| | - Borja Ferrero-Bordera
- Institute of Medical Psychology, Medical Faculty, LMU Munich, Germany (F.S., B.F.-B., M.M.)
| | - Jeffrey Haspel
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO (J.H.)
| | - Markus Sperandio
- Institute for Cardiovascular Physiology and Pathophysiology, Walter Brendel Center for Experimental Medicine, and the Biomedical Center (BMC), Medical Faculty, LMU Munich, Germany (M.S.)
| | - Paul M Holloway
- Radcliffe Department of Medicine, University of Oxford, United Kingdom (P.M.H.)
| | - Martha Merrow
- Institute of Medical Psychology, Medical Faculty, LMU Munich, Germany (F.S., B.F.-B., M.M.)
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Barakat RM, Turcani M, Al-Khaledi G, Kilarkaje N, Al-Sarraf H, Sayed Z, Redzic Z. Low oxygen in inspired air causes severe cerebrocortical hypoxia and cell death in the cerebral cortex of awake rats. Neurosci Lett 2024; 818:137515. [PMID: 37865187 DOI: 10.1016/j.neulet.2023.137515] [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: 03/12/2023] [Revised: 09/12/2023] [Accepted: 10/09/2023] [Indexed: 10/23/2023]
Abstract
Type 1 respiratory failure (T1RF) is associated with secondary acute brain injury (sABI). The underlying mechanisms of sABI could include injury to brain cells mediated either by hypoxia or by lung injury-triggered inflammation. To elucidate to what extent T1RF causes hypoxia and a consequent hypoxic injury in the brain in the absence of lung injury, we exposed healthy, conscious Sprague-Dawley rats to 48 h long low partial pressure of O2 in inspired air (PiO2) (7.5-8 % O2 in N2, CO2 < 0.5 %, normal barometric pressure) and measured the partial pressure of oxygen in the premotor cortex (PtO2), cerebral blood flow (CBF), lactate concentrations, and cell death. Low PiO2 significantly affected PtO2, which was 52.3 (SD 2.1) mmHg when PiO2 was normal but declined to 6.4 (SD 3.8) mmHg when PiO2 was low for 1 h. This was accompanied by increased lactate concentrations in plasma, CSF, and premotor cortex. Low PiO2 elevated the number of dead cells in the cerebral cortex from 5.6 (SD 4.8) % (when PiO2 was normal) to 20.5 (SD 4.1) % and 32.37 (SD 6.5) % after 24 h and 48 h exposure to low PiO2, respectively. The Mann-Kendall test could not detect any monotonic increase or decrease in pial blood flow during the 48 h exposure to low PiO2. In summary, our findings suggest that exposure to low PiO2 caused a severe hypoxia in the cerebral cortex, which triggers a massive cell death. Since these conditions mimic T1RF, hypoxic injury could be an important underlying cause of T1RF-induced sABI.
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Affiliation(s)
- Rawan M Barakat
- Department of Physiology, College of Medicine, Kuwait University, Kuwait
| | - Marian Turcani
- Department of Physiology, College of Medicine, Kuwait University, Kuwait
| | - Ghanim Al-Khaledi
- Department of Pharmacology, College of Medicine, Kuwait University, Kuwait
| | | | - Hameed Al-Sarraf
- Department of Physiology, College of Medicine, Kuwait University, Kuwait
| | - Zeinab Sayed
- Department of Physiology, College of Medicine, Kuwait University, Kuwait
| | - Zoran Redzic
- Department of Physiology, College of Medicine, Kuwait University, Kuwait.
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Cui S, Pratx G. 3D computational model of oxygen depletion kinetics in brain vasculature during FLASH RT, and its implications for in vivo oximetry experiments. Med Phys 2022; 49:3914-3925. [PMID: 35393643 DOI: 10.1002/mp.15642] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 02/19/2022] [Accepted: 03/23/2022] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Ultra-high dose rate irradiation, also known as FLASH, has been shown to improve the therapeutic ratio of radiation therapy (RT). The mechanism behind this effect has been partially explained by the radiochemical oxygen depletion (ROD) hypothesis, which attributes the protection of the normal tissue to the induction of transient hypoxia by ROD. To better understand the contribution of oxygen to the FLASH effect, it is necessary to measure oxygen (O2 ) in vivo during FLASH irradiation. This study's goal is to determine the temporal resolution required to accurately measure the rapidly changing oxygen concentration immediately after FLASH irradiation. METHODS We conducted a computational simulation of oxygen dynamics using a real vascular model that was constructed from a public fluorescence microscopy dataset. The dynamic distribution of oxygen tension (po2 ) during and after FLASH RT was modeled by a partial differential equation (PDE) considering oxygen diffusion, metabolism, and ROD. The underestimation of ROD due to oxygen recovery was evaluated assuming either complete or partial depletion, and a range of possible values for parameters such as oxygen diffusion, consumption, vascular po2 and vessel density. RESULT The O2 concentration recovers rapidly after FLASH RT. Assuming a temporal resolution of 0.5 s, the estimated ROD is only 50.7% and 36.7% of its actual value in cases of partial and complete depletion, respectively. Additionally, the underestimation of ROD is highly dependent on the vascular density. To estimate ROD rate with 90% accuracy, temporal resolution on the order of milliseconds is required considering the uncertainty in parameters involved, especially, the diverse vascular density of the tissue. CONCLUSION The rapid recovery of O2 poses a great challenge for in vivo ROD measurements during FLASH RT. Temporal resolution on the order of milliseconds is recommended for ROD measurements in the normal tissue. Further work is warranted to investigate whether the same requirements apply to tumors, given their irregular vasculature. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Sunan Cui
- Department of Radiation Oncology, Stanford University, Palo Alto, California, USA
| | - Guillem Pratx
- Department of Radiation Oncology, Stanford University, Palo Alto, California, USA
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Markwell SM, Ross JL, Olson CL, Brat DJ. Necrotic reshaping of the glioma microenvironment drives disease progression. Acta Neuropathol 2022; 143:291-310. [PMID: 35039931 DOI: 10.1007/s00401-021-02401-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 12/20/2021] [Accepted: 12/21/2021] [Indexed: 12/13/2022]
Abstract
Glioblastoma is the most common primary brain tumor and has a dismal prognosis. The development of central necrosis represents a tipping point in the evolution of these tumors that foreshadows aggressive expansion, swiftly leading to mortality. The onset of necrosis, severe hypoxia and associated radial glioma expansion correlates with dramatic tumor microenvironment (TME) alterations that accelerate tumor growth. In the past, most have concluded that hypoxia and necrosis must arise due to "cancer outgrowing its blood supply" when rapid tumor growth outpaces metabolic supply, leading to diffusion-limited hypoxia. However, growing evidence suggests that microscopic intravascular thrombosis driven by the neoplastic overexpression of pro-coagulants attenuates glioma blood supply (perfusion-limited hypoxia), leading to TME restructuring that includes breakdown of the blood-brain barrier, immunosuppressive immune cell accumulation, microvascular hyperproliferation, glioma stem cell enrichment and tumor cell migration outward. Cumulatively, these adaptations result in rapid tumor expansion, resistance to therapeutic interventions and clinical progression. To inform future translational investigations, the complex interplay among environmental cues and myriad cell types that contribute to this aggressive phenotype requires better understanding. This review focuses on contributions from intratumoral thrombosis, the effects of hypoxia and necrosis, the adaptive and innate immune responses, and the current state of targeted therapeutic interventions.
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Affiliation(s)
- Steven M Markwell
- Department of Pathology, Northwestern Medicine Malnati Brain Tumor Institute of the Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, 303 E. Chicago Ave. Ward 3-140, Chicago, IL, USA
| | - James L Ross
- Department of Microbiology and Immunology, Emory University, Atlanta, GA, USA
| | - Cheryl L Olson
- Department of Pathology, Northwestern Medicine Malnati Brain Tumor Institute of the Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, 303 E. Chicago Ave. Ward 3-140, Chicago, IL, USA
| | - Daniel J Brat
- Department of Pathology, Northwestern Medicine Malnati Brain Tumor Institute of the Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, 303 E. Chicago Ave. Ward 3-140, Chicago, IL, USA.
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Vandenberg GG, Thotakura A, Scott AL. Mitochondrial bioenergetics of astrocytes in Fragile X Syndrome: new perspectives from culture conditions and sex effects. Am J Physiol Cell Physiol 2021; 322:C125-C135. [PMID: 34817267 DOI: 10.1152/ajpcell.00130.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fragile X syndrome is a genetic disorder that is characterized by a range of cognitive and behavioural deficits, including mild-moderate intellectual disability. The disease is characterized by an X-linked mutation of the Fmr1 gene, which causes silencing of the gene coding for FMRP, a translational regulator integral for neurodevelopment. Mitochondrial dysfunction has been recently associated with FXS, with reports of increases in oxidative stress markers, reactive oxygen species, and lipid peroxidation being present in brain tissue. Astrocytes, a prominent glial cell within the CNS, plays a large role in regulating oxidative homeostasis within the developing brain and dysregulation of astrocyte redox balance in FXS may contribute to oxidative stress. Astrocyte function and mitochondrial bioenergetics is significantly influenced by oxygen availability as well as circulating sex hormones; yet these parameters are rarely considered during in vitro experimentation. Given that the brain normally develops in a range of hypoxic conditions and FXS is a sex-linked genetic disorder, we investigated how different oxygen levels (normoxic versus hypoxic) and biological sex affected mitochondrial bioenergetics of astrocytes in FXS. Our results show demonstrate that both mitochondrial respiration capacity and reactive oxygen species emission are altered with Fmr1 deletion in astrocytes and these changes were dependent upon both sexual dimorphism and oxygen availability.
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Affiliation(s)
- Gregory G Vandenberg
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Aasritha Thotakura
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Angela L Scott
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
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Stepanova A, Galkin A. Measurement of mitochondrial H 2O 2 production under varying O 2 tensions. Methods Cell Biol 2020; 155:273-293. [PMID: 32183962 PMCID: PMC9897472 DOI: 10.1016/bs.mcb.2019.12.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Mitochondria-derived reactive oxygen species (ROS) play an important role in the development of several pathologies and are also involved in physiological signaling. Molecular oxygen is the direct substrate of complex IV of the respiratory chain, and at the same time, its partial reduction in mitochondria results in the formation of ROS, mainly H2O2. The accurate knowledge of the dependence of H2O2 production on oxygen concentration is vital for the studies of tissue ischemia/reperfusion, where the relationship between oxygen availability, respiration, and ROS production is critical. In this chapter, we describe a straightforward and reliable protocol for the assessment of H2O2 release by mitochondria at varying oxygen concentrations. This method can be used for any ROS-generating system where the effect of oxygen level on H2O2 production needs to be assessed.
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Erdener ŞE, Tang J, Sajjadi A, Kılıç K, Kura S, Schaffer CB, Boas DA. Spatio-temporal dynamics of cerebral capillary segments with stalling red blood cells. J Cereb Blood Flow Metab 2019; 39:886-900. [PMID: 29168661 PMCID: PMC6501506 DOI: 10.1177/0271678x17743877] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Optical coherence tomography (OCT) allows label-free imaging of red blood cell (RBC) flux within capillaries with high spatio-temporal resolution. In this study, we utilized time-series OCT-angiography to demonstrate interruptions in capillary RBC flux in mouse brain in vivo. We noticed ∼7.5% of ∼200 capillaries had at least one stall in awake mice with chronic windows during a 9-min recording. At any instant, ∼0.45% of capillaries were stalled. Average stall duration was ∼15 s but could last over 1 min. Stalls were more frequent and longer lasting in acute window preparations. Further, isoflurane anesthesia in chronic preparations caused an increase in the number of stalls. In repeated imaging, the same segments had a tendency to stall again over a period of one month. In awake animals, functional stimulation decreased the observance of stalling events. Stalling segments were located distally, away from the first couple of arteriolar-side capillary branches and their average RBC and plasma velocities were lower than nonstalling capillaries within the same region. This first systematic analysis of capillary RBC stalls in the brain, enabled by rapid and continuous volumetric imaging of capillaries with OCT-angiography, will lead to future investigations of the potential role of stalling events in cerebral pathologies.
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Affiliation(s)
- Şefik Evren Erdener
- 1 Optics Division, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Jianbo Tang
- 1 Optics Division, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Amir Sajjadi
- 1 Optics Division, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Kıvılcım Kılıç
- 2 Neurophotonics Center, Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Sreekanth Kura
- 1 Optics Division, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Chris B Schaffer
- 3 Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA
| | - David A Boas
- 1 Optics Division, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.,2 Neurophotonics Center, Department of Biomedical Engineering, Boston University, Boston, MA, USA
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Bordt EA. The importance of controlling in vitro oxygen tension to accurately model in vivo neurophysiology. Neurotoxicology 2017; 66:213-220. [PMID: 29102646 DOI: 10.1016/j.neuro.2017.10.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 10/27/2017] [Accepted: 10/31/2017] [Indexed: 12/13/2022]
Abstract
The majority of in vitro studies modeling in vivo conditions are performed on the lab bench in atmospheric air. However, the oxygen tension (pO2) present in atmospheric air (160mm Hg, ∼21% O2) is in great excess to the pO2 that permeates tissues within the brain (5-45mm Hg, ∼1-6% O2). This review will discuss the differentiation between pO2 in the in vivo environment and the pO2 commonly used during in vitro experiments, and how this could affect assay outcomes. Also highlighted are studies linking changes in pO2 to changes in cellular function, particularly the role of pO2 in mitochondrial function, reactive oxygen species production, and cellular growth and differentiation. The role of hypoxia inducible factor 1 and oxygen sensing is also presented. Finally, emerging literature exploring sex differences in tissue oxygenation is discussed.
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Affiliation(s)
- Evan A Bordt
- Department of Pediatrics, Lurie Center for Autism, Massachusetts General Hospital for Children, Harvard Medical School, Boston, MA, 02129, USA.
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