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Lee LCC, Lo KKW. Shining New Light on Biological Systems: Luminescent Transition Metal Complexes for Bioimaging and Biosensing Applications. Chem Rev 2024; 124:8825-9014. [PMID: 39052606 DOI: 10.1021/acs.chemrev.3c00629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
Luminescence imaging is a powerful and versatile technique for investigating cell physiology and pathology in living systems, making significant contributions to life science research and clinical diagnosis. In recent years, luminescent transition metal complexes have gained significant attention for diagnostic and therapeutic applications due to their unique photophysical and photochemical properties. In this Review, we provide a comprehensive overview of the recent development of luminescent transition metal complexes for bioimaging and biosensing applications, with a focus on transition metal centers with a d6, d8, and d10 electronic configuration. We elucidate the structure-property relationships of luminescent transition metal complexes, exploring how their structural characteristics can be manipulated to control their biological behavior such as cellular uptake, localization, biocompatibility, pharmacokinetics, and biodistribution. Furthermore, we introduce the various design strategies that leverage the interesting photophysical properties of luminescent transition metal complexes for a wide variety of biological applications, including autofluorescence-free imaging, multimodal imaging, organelle imaging, biological sensing, microenvironment monitoring, bioorthogonal labeling, bacterial imaging, and cell viability assessment. Finally, we provide insights into the challenges and perspectives of luminescent transition metal complexes for bioimaging and biosensing applications, as well as their use in disease diagnosis and treatment evaluation.
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Affiliation(s)
- Lawrence Cho-Cheung Lee
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P. R. China
- Laboratory for Synthetic Chemistry and Chemical Biology Limited, Units 1503-1511, 15/F, Building 17W, Hong Kong Science Park, New Territories, Hong Kong, P. R. China
| | - Kenneth Kam-Wing Lo
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P. R. China
- State Key Laboratory of Terahertz and Millimeter Waves, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P. R. China
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2
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Rathbone E, Fu D. Quantitative Optical Imaging of Oxygen in Brain Vasculature. J Phys Chem B 2024; 128:6975-6989. [PMID: 38991095 DOI: 10.1021/acs.jpcb.4c01277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2024]
Abstract
The intimate relationship between neuronal activity and cerebral oxygenation underpins fundamental brain functions like cognition, sensation, and motor control. Optical imaging offers a noninvasive approach to assess brain oxygenation and often serves as an indirect proxy for neuronal activity. However, deciphering neurovascular coupling─the intricate interplay between neuronal activity, blood flow, and oxygen delivery─necessitates independent, high spatial resolution, and high temporal resolution measurements of both microvasculature oxygenation and neuronal activation. This Perspective examines the established optical techniques employed for brain oxygen imaging, specifically functional near-infrared spectroscopy, photoacoustic imaging, optical coherence tomography, and two-photon phosphorescent lifetime microscopy, highlighting their fundamental principles, strengths, and limitations. Several other emerging optical techniques are also introduced. Finally, we discuss key technological challenges and future directions for quantitative optical oxygen imaging, paving the way for a deeper understanding of oxygen metabolism in the brain.
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Affiliation(s)
- Emily Rathbone
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Dan Fu
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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3
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Anbaei P, Stevens MG, Ball AG, Bullock TNJ, Pompano RR. Spatially resolved quantification of oxygen consumption rate in ex vivo lymph node slices. Analyst 2024; 149:2609-2620. [PMID: 38535830 PMCID: PMC11056769 DOI: 10.1039/d4an00028e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Accepted: 03/09/2024] [Indexed: 04/09/2024]
Abstract
Cellular metabolism has been closely linked to activation state in cells of the immune system, and the oxygen consumption rate (OCR) in particular serves as a valuable metric for assessing metabolic activity. Several oxygen sensing assays have been reported for cells in standard culture conditions. However, none have provided a spatially resolved, optical measurement of local oxygen consumption in intact tissue samples, making it challenging to understand regional dynamics of consumption. Therefore, here we established a system to monitor the rates of oxygen consumption in ex vivo tissue slices, using murine lymphoid tissue as a case study. By integrating an optical oxygen sensor into a sealed perfusion chamber and incorporating appropriate correction for photobleaching of the sensor and of tissue autofluorescence, we were able to visualize and quantify rates of oxygen consumption in tissue. This method revealed for the first time that the rate of oxygen consumption in naïve lymphoid tissue was higher in the T cell region compared to the B cell and cortical regions. To validate the method, we measured OCR in the T cell regions of naïve lymph node slices using the optical assay and estimated the consumption rate per cell. The predictions from the optical assay were similar to reported values and were not significantly different from those of the Seahorse metabolic assay, a gold standard method for measuring OCR in cell suspensions. Finally, we used this method to quantify the rate of onset of tissue hypoxia for lymph node slices cultured in a sealed chamber and showed that continuous perfusion was sufficient to maintain oxygenation. In summary, this work establishes a method to monitor oxygen consumption with regional resolution in intact tissue explants, suitable for future use to compare tissue culture conditions and responses to stimulation.
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Affiliation(s)
- Parastoo Anbaei
- Department of Chemistry, University of Virginia College of Arts and, Sciences, Charlottesville, Virginia 22904, USA.
| | - Marissa G Stevens
- Department of Pathology, University of Virginia, Charlottesville, Virginia 22903, USA
- Carter Immunology Center and UVA Cancer Center, University of Virginia, Charlottesville, Virginia 22903, USA
| | - Alexander G Ball
- Department of Microbiology Cancer Biology and Immunology, University of Virginia, Charlottesville, Virginia 22903, USA
- Carter Immunology Center and UVA Cancer Center, University of Virginia, Charlottesville, Virginia 22903, USA
| | - Timothy N J Bullock
- Department of Pathology, University of Virginia, Charlottesville, Virginia 22903, USA
- Carter Immunology Center and UVA Cancer Center, University of Virginia, Charlottesville, Virginia 22903, USA
| | - Rebecca R Pompano
- Department of Chemistry, University of Virginia College of Arts and, Sciences, Charlottesville, Virginia 22904, USA.
- Department of Biomedical Engineering, University of Virginia School of Engineering and Applied Sciences, Charlottesville, Virginia 22904, USA
- Carter Immunology Center and UVA Cancer Center, University of Virginia, Charlottesville, Virginia 22903, USA
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4
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Longden TA, Lederer WJ. Electro-metabolic signaling. J Gen Physiol 2024; 156:e202313451. [PMID: 38197953 PMCID: PMC10783436 DOI: 10.1085/jgp.202313451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 10/27/2023] [Accepted: 12/14/2023] [Indexed: 01/11/2024] Open
Abstract
Precise matching of energy substrate delivery to local metabolic needs is essential for the health and function of all tissues. Here, we outline a mechanistic framework for understanding this critical process, which we refer to as electro-metabolic signaling (EMS). All tissues exhibit changes in metabolism over varying spatiotemporal scales and have widely varying energetic needs and reserves. We propose that across tissues, common signatures of elevated metabolism or increases in energy substrate usage that exceed key local thresholds rapidly engage mechanisms that generate hyperpolarizing electrical signals in capillaries that then relax contractile elements throughout the vasculature to quickly adjust blood flow to meet changing needs. The attendant increase in energy substrate delivery serves to meet local metabolic requirements and thus avoids a mismatch in supply and demand and prevents metabolic stress. We discuss in detail key examples of EMS that our laboratories have discovered in the brain and the heart, and we outline potential further EMS mechanisms operating in tissues such as skeletal muscle, pancreas, and kidney. We suggest that the energy imbalance evoked by EMS uncoupling may be central to cellular dysfunction from which the hallmarks of aging and metabolic diseases emerge and may lead to generalized organ failure states-such as diverse flavors of heart failure and dementia. Understanding and manipulating EMS may be key to preventing or reversing these dysfunctions.
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Affiliation(s)
- Thomas A. Longden
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - W. Jonathan Lederer
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- Laboratory of Molecular Cardiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA
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5
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Anbaei P, Stevens MG, Ball AG, Bullock TNJ, Pompano RR. Spatially resolved quantification of oxygen consumption rate in ex vivo lymph node slices. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.03.573955. [PMID: 38260315 PMCID: PMC10802365 DOI: 10.1101/2024.01.03.573955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Cellular metabolism has been closely linked to activation state in cells of the immune system, and the oxygen consumption rate (OCR) in particular serves as a valuable metric for assessing metabolic activity. Several oxygen sensing assays have been reported for cells in standard culture conditions. However, none have provided a spatially resolved, optical measurement of local oxygen consumption in intact tissue samples, making it challenging to understand regional dynamics of consumption. Therefore, here we established a system to monitor the rates of oxygen consumption in ex vivo tissue slices, using murine lymphoid tissue as a case study. By integrating an optical oxygen sensor into a sealed perfusion chamber and incorporating appropriate correction for photobleaching of the sensor and of tissue autofluorescence, we were able to visualize and quantify rates of oxygen consumption in tissue. This method revealed for the first time that the rate of oxygen consumption in naïve lymphoid tissue was higher in the T cell region compared to the B cell and cortical regions. To validate the method, we measured OCR in the T cell regions of naïve lymph node slices using the optical assay and estimated the consumption rate per cell. The predictions from the optical assay were similar to reported values and were not significantly different from those of the Seahorse metabolic assay, a gold standard method for measuring OCR in cell suspensions. Finally, we used this method to quantify the rate of onset of tissue hypoxia for lymph node slices cultured in a sealed chamber and showed that continuous perfusion was sufficient to maintain oxygenation. In summary, this work establishes a method to monitor oxygen consumption with regional resolution in intact tissue explants, suitable for future use to compare tissue culture conditions and responses to stimulation. TOC image
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Alarcon-Martinez L, Shiga Y, Villafranca-Baughman D, Cueva Vargas JL, Vidal Paredes IA, Quintero H, Fortune B, Danesh-Meyer H, Di Polo A. Neurovascular dysfunction in glaucoma. Prog Retin Eye Res 2023; 97:101217. [PMID: 37778617 DOI: 10.1016/j.preteyeres.2023.101217] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 09/23/2023] [Accepted: 09/25/2023] [Indexed: 10/03/2023]
Abstract
Retinal ganglion cells, the neurons that die in glaucoma, are endowed with a high metabolism requiring optimal provision of oxygen and nutrients to sustain their activity. The timely regulation of blood flow is, therefore, essential to supply firing neurons in active areas with the oxygen and glucose they need for energy. Many glaucoma patients suffer from vascular deficits including reduced blood flow, impaired autoregulation, neurovascular coupling dysfunction, and blood-retina/brain-barrier breakdown. These processes are tightly regulated by a community of cells known as the neurovascular unit comprising neurons, endothelial cells, pericytes, Müller cells, astrocytes, and microglia. In this review, the neurovascular unit takes center stage as we examine the ability of its members to regulate neurovascular interactions and how their function might be altered during glaucomatous stress. Pericytes receive special attention based on recent data demonstrating their key role in the regulation of neurovascular coupling in physiological and pathological conditions. Of particular interest is the discovery and characterization of tunneling nanotubes, thin actin-based conduits that connect distal pericytes, which play essential roles in the complex spatial and temporal distribution of blood within the retinal capillary network. We discuss cellular and molecular mechanisms of neurovascular interactions and their pathophysiological implications, while highlighting opportunities to develop strategies for vascular protection and regeneration to improve functional outcomes in glaucoma.
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Affiliation(s)
- Luis Alarcon-Martinez
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada; Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia
| | - Yukihiro Shiga
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Deborah Villafranca-Baughman
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Jorge L Cueva Vargas
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Isaac A Vidal Paredes
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Heberto Quintero
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Brad Fortune
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Healthy, Portland, OR, USA
| | - Helen Danesh-Meyer
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Adriana Di Polo
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada.
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7
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Li B, Yabluchanskiy A, Tarantini S, Allu SR, Şencan-Eğilmez I, Leng J, Alfadhel MAH, Porter JE, Fu B, Ran C, Erdener SE, Boas DA, Vinogradov SA, Sonntag WE, Csiszar A, Ungvari Z, Sakadžić S. Measurements of cerebral microvascular blood flow, oxygenation, and morphology in a mouse model of whole-brain irradiation-induced cognitive impairment by two-photon microscopy and optical coherence tomography: evidence for microvascular injury in the cerebral white matter. GeroScience 2023; 45:1491-1510. [PMID: 36792820 PMCID: PMC10400746 DOI: 10.1007/s11357-023-00735-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 01/17/2023] [Indexed: 02/17/2023] Open
Abstract
Whole-brain irradiation (WBI, also known as whole-brain radiation therapy) is a mainstay treatment modality for patients with multiple brain metastases. It is also used as a prophylactic treatment for microscopic tumors that cannot be detected by magnetic resonance imaging. WBI induces a progressive cognitive decline in ~ 50% of the patients surviving over 6 months, significantly compromising the quality of life. There is increasing preclinical evidence that radiation-induced injury to the cerebral microvasculature and accelerated neurovascular senescence plays a central role in this side effect of WBI. To better understand this side effect, male C57BL/6 mice were first subjected to a clinically relevant protocol of fractionated WBI (5 Gy, two doses per week, for 4 weeks). Nine months post the WBI treatment, we applied two-photon microscopy and Doppler optical coherence tomography to measure capillary red-blood-cell (RBC) flux, capillary morphology, and microvascular oxygen partial pressure (PO2) in the cerebral somatosensory cortex in the awake, head-restrained, WPI-treated mice and their age-matched controls, through a cover-glass-sealed chronic cranial window. Thanks to the extended penetration depth with the fluorophore - Alexa680, measurements of capillary blood flow properties (e.g., RBC flux, speed, and linear density) in the cerebral subcortical white matter were enabled. We found that the WBI-treated mice exhibited a significantly decreased capillary RBC flux in the white matter. WBI also caused a significant reduction in capillary diameter, as well as a large (although insignificant) reduction in segment density at the deeper cortical layers (e.g., 600-700 μm), while the other morphological properties (e.g., segment length and tortuosity) were not obviously affected. In addition, we found that PO2 measured in the arterioles and venules, as well as the calculated oxygen saturation and oxygen extraction fraction, were not obviously affected by WBI. Lastly, WBI was associated with a significant increase in the erythrocyte-associated transients of PO2, while the changes of other cerebral capillary PO2 properties (e.g., capillary mean-PO2, RBC-PO2, and InterRBC-PO2) were not significant. Collectively, our findings support the notion that WBI results in persistent cerebral white matter microvascular impairment, which likely contributes to the WBI-induced brain injury and cognitive decline. Further studies are warranted to assess the WBI-induced changes in brain tissue oxygenation and malfunction of the white matter microvasculature as well.
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Affiliation(s)
- Baoqiang Li
- Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
| | - Andriy Yabluchanskiy
- Vascular Cognitive Impairment and Neurodegeneration Program, Oklahoma Center for Geroscience and Healthy Brain Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- The Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Stefano Tarantini
- Vascular Cognitive Impairment and Neurodegeneration Program, Oklahoma Center for Geroscience and Healthy Brain Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- The Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine/Department of Public Health, Semmelweis University, Budapest, 1083, Hungary
| | - Srinivasa Rao Allu
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Ikbal Şencan-Eğilmez
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
- Biophotonics Research Center, Department of Radiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Ji Leng
- Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China
| | - Mohammed Ali H Alfadhel
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
| | - Jason E Porter
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
| | - Buyin Fu
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
| | - Chongzhao Ran
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
| | - Sefik Evren Erdener
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA
| | - David A Boas
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - William E Sonntag
- Vascular Cognitive Impairment and Neurodegeneration Program, Oklahoma Center for Geroscience and Healthy Brain Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- The Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Anna Csiszar
- Vascular Cognitive Impairment and Neurodegeneration Program, Oklahoma Center for Geroscience and Healthy Brain Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- The Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine/Department of Translational Medicine, Semmelweis University, Budapest, 1083, Hungary
| | - Zoltan Ungvari
- Vascular Cognitive Impairment and Neurodegeneration Program, Oklahoma Center for Geroscience and Healthy Brain Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.
- Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.
- The Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine/Department of Public Health, Semmelweis University, Budapest, 1083, Hungary.
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA.
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Zaidi AD, Birbaumer N, Fetz E, Logothetis N, Sitaram R. The hemodynamic initial-dip consists of both volumetric and oxymetric changes reflecting localized spiking activity. Front Neurosci 2023; 17:1170401. [PMID: 37304038 PMCID: PMC10248142 DOI: 10.3389/fnins.2023.1170401] [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: 02/20/2023] [Accepted: 04/28/2023] [Indexed: 06/13/2023] Open
Abstract
The initial-dip is a transient decrease frequently observed in functional neuroimaging signals, immediately after stimulus onset, believed to originate from a rise in deoxy-hemoglobin (HbR) caused by local neural activity. It has been shown to be more spatially specific than the hemodynamic response, and is believed to represent focal neuronal activity. However, despite being observed in various neuroimaging modalities (such as fMRI, fNIRS, etc), its origins are disputed, and its precise neuronal correlates are unknown. Here we show that the initial-dip is dominated by a decrease in total-hemoglobin (HbT). We also find a biphasic response in deoxy-Hb (HbR), with an early decrease and later rebound. Both the HbT-dip and HbR-rebound were strongly correlated to highly localized spiking activity. However, HbT decreases were always large enough to counter the spiking-induced increase in HbR. We find that the HbT-dip counters spiking induced HbR increases, imposing an upper-limit to HbR concentration in the capillaries. Building on our results, we explore the possibility of active venule dilation (purging) as a possible mechanism for the HbT dip.
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Affiliation(s)
- Ali Danish Zaidi
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
- Institute for Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
- Department of Physiology and Biophysics, University of Washington, Seattle, WA, United States
| | - Niels Birbaumer
- Center for Imaging Sciences, Biomedical Imaging Institute, University of Manchester, Manchester, United Kingdom
| | - Eberhard Fetz
- Institute of Biological and Medical Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Nikos Logothetis
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
- Department of Psychiatry and Section of Neuroscience, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Ranganatha Sitaram
- Institute of Biological and Medical Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile
- Department of Psychiatry and Section of Neuroscience, Pontificia Universidad Católica de Chile, Santiago, Chile
- Multimodal Functional Brain Imaging and Neurorehabilitation Hub, Diagnostic Imaging Department, St. Jude Children's Research Hospital, Memphis, TN, United States
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Abstract
Sensory stimulation generates a robust decrease in oxygen concentration (pO2 initial dip) in brain tissue of anesthetized cats and rodents. This dip reports local activation of neurons much better than the delayed pO2 increase associated with functional hyperemia. Here, we reinvestigated the issue in animals that recovered from acute surgery using two-photon lifetime microscopy. Targeting a distinct neuronal network that is the site of strong activation and energy consumption, we show that in anesthetized animals the pO2 initial dip is present but extremely small in juxtasynaptic capillaries. In awake animals, it is no longer detectable in vessels or in the neuropil. This demonstrates that in healthy animals, neurovascular coupling is too fast and efficient to reveal a pO2 initial dip. An ongoing controversy in brain metabolism is whether increases in neural activity cause a local and rapid decrease in oxygen concentration (i.e., the “initial dip”) preceding functional hyperemia. This initial dip has been suggested to cause a transient increase in vascular deoxyhemoglobin with several imaging techniques and stimulation paradigms, but not consistently. Here, we investigate contributors to this initial dip in a distinct neuronal network, an olfactory bulb (OB) glomerulus most sensitive to a specific odorant (ethyl tiglate [ET]) and a site of strong activation and energy consumption upon ET stimulation. Combining two-photon fluorescence and phosphorescence lifetime microscopy, and calcium, blood flow, and pO2 measurements, we characterized this initial dip in pO2 in mice chronically implanted with a glass cranial window, during both awake and anesthetized conditions. In anesthetized mice, a transient dip in vascular pO2 was detected in this glomerulus when functional hyperemia was slightly delayed, but its amplitude was minute (0.3 SD of resting baseline). This vascular pO2 dip was not observed in other glomeruli responding nonspecifically to ET, and it was poorly influenced by resting pO2. In awake mice, the dip in pO2 was absent in capillaries as well as, surprisingly, in the neuropil. These high-resolution pO2 measurements demonstrate that in awake mice recovered from brain surgery, neurovascular coupling was too fast and efficient to reveal an initial dip in pO2.
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10
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Şencan İ, Esipova T, Kılıç K, Li B, Desjardins M, Yaseen MA, Wang H, Porter JE, Kura S, Fu B, Secomb TW, Boas DA, Vinogradov SA, Devor A, Sakadžić S. Optical measurement of microvascular oxygenation and blood flow responses in awake mouse cortex during functional activation. J Cereb Blood Flow Metab 2022; 42:510-525. [PMID: 32515672 PMCID: PMC8985437 DOI: 10.1177/0271678x20928011] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The cerebral cortex has a number of conserved morphological and functional characteristics across brain regions and species. Among them, the laminar differences in microvascular density and mitochondrial cytochrome c oxidase staining suggest potential laminar variability in the baseline O2 metabolism and/or laminar variability in both O2 demand and hemodynamic response. Here, we investigate the laminar profile of stimulus-induced intravascular partial pressure of O2 (pO2) transients to stimulus-induced neuronal activation in fully awake mice using two-photon phosphorescence lifetime microscopy. Our results demonstrate that stimulus-induced changes in intravascular pO2 are conserved across cortical layers I-IV, suggesting a tightly controlled neurovascular response to provide adequate O2 supply across cortical depth. In addition, we observed a larger change in venular O2 saturation (ΔsO2) compared to arterioles, a gradual increase in venular ΔsO2 response towards the cortical surface, and absence of the intravascular "initial dip" previously reported under anesthesia. This study paves the way for quantification of layer-specific cerebral O2 metabolic responses, facilitating investigation of brain energetics in health and disease and informed interpretation of laminar blood oxygen level dependent functional magnetic resonance imaging signals.
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Affiliation(s)
- İkbal Şencan
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Tatiana Esipova
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, USA
| | - Kıvılcım Kılıç
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Baoqiang Li
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Michèle Desjardins
- Department of Physics, Engineering Physics and Optics, Université Laval, QC, Canada
| | - Mohammad A Yaseen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Hui Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Jason E Porter
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Sreekanth Kura
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Buyin Fu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Timothy W Secomb
- Department of Physiology, University of Arizona, Tucson, AZ, USA
| | - David A Boas
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, USA
| | - Anna Devor
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.,Department of Biomedical Engineering, Boston University, Boston, MA, USA.,Department of Neurosciences, University of California San Diego, La Jolla, CA, USA.,Department of Radiology, University of California San Diego, La Jolla, CA, USA
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
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11
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Yoshihara T, Matsumura N, Tamura T, Shiozaki S, Tobita S. Intracellular and Intravascular Oxygen Sensing of Pancreatic Tissues Based on Phosphorescence Lifetime Imaging Microscopy Using Lipophilic and Hydrophilic Iridium(III) Complexes. ACS Sens 2022; 7:545-554. [PMID: 35113520 DOI: 10.1021/acssensors.1c02379] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Simultaneous imaging of intracellular and blood oxygen levels in tissues provides valuable information on the dynamic behavior of molecular oxygen (O2) in normal and diseased tissues. Here, to achieve this goal, we developed green-emitting intracellular O2 probes based on the Ir(III) complex, PPY (tris(2-phenylpyridinato)iridium(III)), and investigated the possibility of multicolor O2 imaging by co-staining tissues with a red-emitting intravascular probe BTP-PEG48. The newly synthesized complexes possess modified 2-phenylpyridinato ligand(s) with a cationic or hydrophilic substituent, such as a dimethylamino group, triphenylphosphonium cation, or hydroxy group, in order to enhance cellular uptake efficiency. The photophysical and cellular properties of these complexes were systematically investigated to evaluate their ability as O2 probes. Among these complexes, PPYDM and PPY2OH, which have a dimethylamino group and two hydroxy groups, respectively, exhibited much higher cellular uptake efficiencies compared with PPY and showed high O2 sensitivity in HeLa cells. Phosphorescence lifetime imaging microscopy (PLIM) measurements of HeLa cells co-stained with PPYDM and hydrophilic BTP-PEG48 allowed for the evaluation of intracellular and extracellular O2 levels in cell culture. We took PLIM images of the pancreas following intravenous administration of PPYDM and BTP-PEG48 into anesthetized mice. The PLIM measurements using these probes allowed simultaneous O2 imaging of acinar cells and capillaries in the pancreas with cellular-level resolution. From the phosphorescence lifetimes of PPYDM and BTP-PEG48 and the calibration curves evaluated in rat pancreatic acinar cells and blood plasma, we found that the average oxygen partial pressures of acinar cells and capillaries were almost equal at about 30 mmHg.
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Affiliation(s)
- Toshitada Yoshihara
- Department of Chemistry and Chemical Biology, Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japan
| | - Nao Matsumura
- Department of Chemistry and Chemical Biology, Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japan
| | - Takuto Tamura
- Department of Chemistry and Chemical Biology, Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japan
| | - Shuichi Shiozaki
- Department of Chemistry and Chemical Biology, Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japan
| | - Seiji Tobita
- Department of Chemistry and Chemical Biology, Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japan
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12
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Abdelfattah AS, Ahuja S, Akkin T, Allu SR, Brake J, Boas DA, Buckley EM, Campbell RE, Chen AI, Cheng X, Čižmár T, Costantini I, De Vittorio M, Devor A, Doran PR, El Khatib M, Emiliani V, Fomin-Thunemann N, Fainman Y, Fernandez-Alfonso T, Ferri CGL, Gilad A, Han X, Harris A, Hillman EMC, Hochgeschwender U, Holt MG, Ji N, Kılıç K, Lake EMR, Li L, Li T, Mächler P, Miller EW, Mesquita RC, Nadella KMNS, Nägerl UV, Nasu Y, Nimmerjahn A, Ondráčková P, Pavone FS, Perez Campos C, Peterka DS, Pisano F, Pisanello F, Puppo F, Sabatini BL, Sadegh S, Sakadzic S, Shoham S, Shroff SN, Silver RA, Sims RR, Smith SL, Srinivasan VJ, Thunemann M, Tian L, Tian L, Troxler T, Valera A, Vaziri A, Vinogradov SA, Vitale F, Wang LV, Uhlířová H, Xu C, Yang C, Yang MH, Yellen G, Yizhar O, Zhao Y. Neurophotonic tools for microscopic measurements and manipulation: status report. NEUROPHOTONICS 2022; 9:013001. [PMID: 35493335 PMCID: PMC9047450 DOI: 10.1117/1.nph.9.s1.013001] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Neurophotonics was launched in 2014 coinciding with the launch of the BRAIN Initiative focused on development of technologies for advancement of neuroscience. For the last seven years, Neurophotonics' agenda has been well aligned with this focus on neurotechnologies featuring new optical methods and tools applicable to brain studies. While the BRAIN Initiative 2.0 is pivoting towards applications of these novel tools in the quest to understand the brain, this status report reviews an extensive and diverse toolkit of novel methods to explore brain function that have emerged from the BRAIN Initiative and related large-scale efforts for measurement and manipulation of brain structure and function. Here, we focus on neurophotonic tools mostly applicable to animal studies. A companion report, scheduled to appear later this year, will cover diffuse optical imaging methods applicable to noninvasive human studies. For each domain, we outline the current state-of-the-art of the respective technologies, identify the areas where innovation is needed, and provide an outlook for the future directions.
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Affiliation(s)
- Ahmed S. Abdelfattah
- Brown University, Department of Neuroscience, Providence, Rhode Island, United States
| | - Sapna Ahuja
- University of Pennsylvania, Perelman School of Medicine, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, School of Arts and Sciences, Department of Chemistry, Philadelphia, Pennsylvania, United States
| | - Taner Akkin
- University of Minnesota, Department of Biomedical Engineering, Minneapolis, Minnesota, United States
| | - Srinivasa Rao Allu
- University of Pennsylvania, Perelman School of Medicine, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, School of Arts and Sciences, Department of Chemistry, Philadelphia, Pennsylvania, United States
| | - Joshua Brake
- Harvey Mudd College, Department of Engineering, Claremont, California, United States
| | - David A. Boas
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Erin M. Buckley
- Georgia Institute of Technology and Emory University, Wallace H. Coulter Department of Biomedical Engineering, Atlanta, Georgia, United States
- Emory University, Department of Pediatrics, Atlanta, Georgia, United States
| | - Robert E. Campbell
- University of Tokyo, Department of Chemistry, Tokyo, Japan
- University of Alberta, Department of Chemistry, Edmonton, Alberta, Canada
| | - Anderson I. Chen
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Xiaojun Cheng
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Tomáš Čižmár
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czech Republic
| | - Irene Costantini
- University of Florence, European Laboratory for Non-Linear Spectroscopy, Department of Biology, Florence, Italy
- National Institute of Optics, National Research Council, Rome, Italy
| | - Massimo De Vittorio
- Istituto Italiano di Tecnologia, Center for Biomolecular Nanotechnologies, Arnesano, Italy
| | - Anna Devor
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
| | - Patrick R. Doran
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Mirna El Khatib
- University of Pennsylvania, Perelman School of Medicine, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, School of Arts and Sciences, Department of Chemistry, Philadelphia, Pennsylvania, United States
| | | | - Natalie Fomin-Thunemann
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Yeshaiahu Fainman
- University of California San Diego, Department of Electrical and Computer Engineering, La Jolla, California, United States
| | - Tomas Fernandez-Alfonso
- University College London, Department of Neuroscience, Physiology and Pharmacology, London, United Kingdom
| | - Christopher G. L. Ferri
- University of California San Diego, Departments of Neurosciences, La Jolla, California, United States
| | - Ariel Gilad
- The Hebrew University of Jerusalem, Institute for Medical Research Israel–Canada, Department of Medical Neurobiology, Faculty of Medicine, Jerusalem, Israel
| | - Xue Han
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Andrew Harris
- Weizmann Institute of Science, Department of Brain Sciences, Rehovot, Israel
| | | | - Ute Hochgeschwender
- Central Michigan University, Department of Neuroscience, Mount Pleasant, Michigan, United States
| | - Matthew G. Holt
- University of Porto, Instituto de Investigação e Inovação em Saúde (i3S), Porto, Portugal
| | - Na Ji
- University of California Berkeley, Department of Physics, Berkeley, California, United States
| | - Kıvılcım Kılıç
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Evelyn M. R. Lake
- Yale School of Medicine, Department of Radiology and Biomedical Imaging, New Haven, Connecticut, United States
| | - Lei Li
- California Institute of Technology, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, Pasadena, California, United States
| | - Tianqi Li
- University of Minnesota, Department of Biomedical Engineering, Minneapolis, Minnesota, United States
| | - Philipp Mächler
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Evan W. Miller
- University of California Berkeley, Departments of Chemistry and Molecular & Cell Biology and Helen Wills Neuroscience Institute, Berkeley, California, United States
| | | | | | - U. Valentin Nägerl
- Interdisciplinary Institute for Neuroscience University of Bordeaux & CNRS, Bordeaux, France
| | - Yusuke Nasu
- University of Tokyo, Department of Chemistry, Tokyo, Japan
| | - Axel Nimmerjahn
- Salk Institute for Biological Studies, Waitt Advanced Biophotonics Center, La Jolla, California, United States
| | - Petra Ondráčková
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czech Republic
| | - Francesco S. Pavone
- National Institute of Optics, National Research Council, Rome, Italy
- University of Florence, European Laboratory for Non-Linear Spectroscopy, Department of Physics, Florence, Italy
| | - Citlali Perez Campos
- Columbia University, Zuckerman Mind Brain Behavior Institute, New York, United States
| | - Darcy S. Peterka
- Columbia University, Zuckerman Mind Brain Behavior Institute, New York, United States
| | - Filippo Pisano
- Istituto Italiano di Tecnologia, Center for Biomolecular Nanotechnologies, Arnesano, Italy
| | - Ferruccio Pisanello
- Istituto Italiano di Tecnologia, Center for Biomolecular Nanotechnologies, Arnesano, Italy
| | - Francesca Puppo
- University of California San Diego, Departments of Neurosciences, La Jolla, California, United States
| | - Bernardo L. Sabatini
- Harvard Medical School, Howard Hughes Medical Institute, Department of Neurobiology, Boston, Massachusetts, United States
| | - Sanaz Sadegh
- University of California San Diego, Departments of Neurosciences, La Jolla, California, United States
| | - Sava Sakadzic
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
| | - Shy Shoham
- New York University Grossman School of Medicine, Tech4Health and Neuroscience Institutes, New York, New York, United States
| | - Sanaya N. Shroff
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - R. Angus Silver
- University College London, Department of Neuroscience, Physiology and Pharmacology, London, United Kingdom
| | - Ruth R. Sims
- Sorbonne University, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Spencer L. Smith
- University of California Santa Barbara, Department of Electrical and Computer Engineering, Santa Barbara, California, United States
| | - Vivek J. Srinivasan
- New York University Langone Health, Departments of Ophthalmology and Radiology, New York, New York, United States
| | - Martin Thunemann
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Lei Tian
- Boston University, Departments of Electrical Engineering and Biomedical Engineering, Boston, Massachusetts, United States
| | - Lin Tian
- University of California Davis, Department of Biochemistry and Molecular Medicine, Davis, California, United States
| | - Thomas Troxler
- University of Pennsylvania, Perelman School of Medicine, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, School of Arts and Sciences, Department of Chemistry, Philadelphia, Pennsylvania, United States
| | - Antoine Valera
- University College London, Department of Neuroscience, Physiology and Pharmacology, London, United Kingdom
| | - Alipasha Vaziri
- Rockefeller University, Laboratory of Neurotechnology and Biophysics, New York, New York, United States
- The Rockefeller University, The Kavli Neural Systems Institute, New York, New York, United States
| | - Sergei A. Vinogradov
- University of Pennsylvania, Perelman School of Medicine, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, School of Arts and Sciences, Department of Chemistry, Philadelphia, Pennsylvania, United States
| | - Flavia Vitale
- Center for Neuroengineering and Therapeutics, Departments of Neurology, Bioengineering, Physical Medicine and Rehabilitation, Philadelphia, Pennsylvania, United States
| | - Lihong V. Wang
- California Institute of Technology, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, Pasadena, California, United States
| | - Hana Uhlířová
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czech Republic
| | - Chris Xu
- Cornell University, School of Applied and Engineering Physics, Ithaca, New York, United States
| | - Changhuei Yang
- California Institute of Technology, Departments of Electrical Engineering, Bioengineering and Medical Engineering, Pasadena, California, United States
| | - Mu-Han Yang
- University of California San Diego, Department of Electrical and Computer Engineering, La Jolla, California, United States
| | - Gary Yellen
- Harvard Medical School, Department of Neurobiology, Boston, Massachusetts, United States
| | - Ofer Yizhar
- Weizmann Institute of Science, Department of Brain Sciences, Rehovot, Israel
| | - Yongxin Zhao
- Carnegie Mellon University, Department of Biological Sciences, Pittsburgh, Pennsylvania, United States
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13
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Network-driven anomalous transport is a fundamental component of brain microvascular dysfunction. Nat Commun 2021; 12:7295. [PMID: 34911962 PMCID: PMC8674232 DOI: 10.1038/s41467-021-27534-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 11/18/2021] [Indexed: 12/17/2022] Open
Abstract
Blood microcirculation supplies neurons with oxygen and nutrients, and contributes to clearing their neurotoxic waste, through a dense capillary network connected to larger tree-like vessels. This complex microvascular architecture results in highly heterogeneous blood flow and travel time distributions, whose origin and consequences on brain pathophysiology are poorly understood. Here, we analyze highly-resolved intracortical blood flow and transport simulations to establish the physical laws governing the macroscopic transport properties in the brain micro-circulation. We show that network-driven anomalous transport leads to the emergence of critical regions, whether hypoxic or with high concentrations of amyloid-β, a waste product centrally involved in Alzheimer's Disease. We develop a Continuous-Time Random Walk theory capturing these dynamics and predicting that such critical regions appear much earlier than anticipated by current empirical models under mild hypoperfusion. These findings provide a framework for understanding and modelling the impact of microvascular dysfunction in brain diseases, including Alzheimer's Disease.
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14
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Zhang Q, Gheres KW, Drew PJ. Origins of 1/f-like tissue oxygenation fluctuations in the murine cortex. PLoS Biol 2021; 19:e3001298. [PMID: 34264930 PMCID: PMC8282088 DOI: 10.1371/journal.pbio.3001298] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 05/24/2021] [Indexed: 01/07/2023] Open
Abstract
The concentration of oxygen in the brain spontaneously fluctuates, and the distribution of power in these fluctuations has a 1/f-like spectra, where the power present at low frequencies of the power spectrum is orders of magnitude higher than at higher frequencies. Though these oscillations have been interpreted as being driven by neural activity, the origin of these 1/f-like oscillations is not well understood. Here, to gain insight of the origin of the 1/f-like oxygen fluctuations, we investigated the dynamics of tissue oxygenation and neural activity in awake behaving mice. We found that oxygen signal recorded from the cortex of mice had 1/f-like spectra. However, band-limited power in the local field potential did not show corresponding 1/f-like fluctuations. When local neural activity was suppressed, the 1/f-like fluctuations in oxygen concentration persisted. Two-photon measurements of erythrocyte spacing fluctuations and mathematical modeling show that stochastic fluctuations in erythrocyte flow could underlie 1/f-like dynamics in oxygenation. These results suggest that the discrete nature of erythrocytes and their irregular flow, rather than fluctuations in neural activity, could drive 1/f-like fluctuations in tissue oxygenation.
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Affiliation(s)
- Qingguang Zhang
- Center for Neural Engineering, Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail: (QZ); (PJD)
| | - Kyle W. Gheres
- Graduate Program in Molecular Cellular and Integrative Biosciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Patrick J. Drew
- Center for Neural Engineering, Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Neurosurgery, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail: (QZ); (PJD)
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15
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Shaw K, Bell L, Boyd K, Grijseels DM, Clarke D, Bonnar O, Crombag HS, Hall CN. Neurovascular coupling and oxygenation are decreased in hippocampus compared to neocortex because of microvascular differences. Nat Commun 2021; 12:3190. [PMID: 34045465 PMCID: PMC8160329 DOI: 10.1038/s41467-021-23508-y] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 04/26/2021] [Indexed: 02/04/2023] Open
Abstract
The hippocampus is essential for spatial and episodic memory but is damaged early in Alzheimer's disease and is very sensitive to hypoxia. Understanding how it regulates its oxygen supply is therefore key for designing interventions to preserve its function. However, studies of neurovascular function in the hippocampus in vivo have been limited by its relative inaccessibility. Here we compared hippocampal and visual cortical neurovascular function in awake mice, using two photon imaging of individual neurons and vessels and measures of regional blood flow and haemoglobin oxygenation. We show that blood flow, blood oxygenation and neurovascular coupling were decreased in the hippocampus compared to neocortex, because of differences in both the vascular network and pericyte and endothelial cell function. Modelling oxygen diffusion indicates that these features of the hippocampal vasculature may restrict oxygen availability and could explain its sensitivity to damage during neurological conditions, including Alzheimer's disease, where the brain's energy supply is decreased.
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Affiliation(s)
- K Shaw
- School of Psychology and Sussex Neuroscience, University of Sussex, Falmer, Brighton, United Kingdom
| | - L Bell
- School of Psychology and Sussex Neuroscience, University of Sussex, Falmer, Brighton, United Kingdom
| | - K Boyd
- School of Psychology and Sussex Neuroscience, University of Sussex, Falmer, Brighton, United Kingdom
| | - D M Grijseels
- School of Psychology and Sussex Neuroscience, University of Sussex, Falmer, Brighton, United Kingdom
| | - D Clarke
- School of Psychology and Sussex Neuroscience, University of Sussex, Falmer, Brighton, United Kingdom
| | - O Bonnar
- School of Psychology and Sussex Neuroscience, University of Sussex, Falmer, Brighton, United Kingdom
| | - H S Crombag
- School of Psychology and Sussex Neuroscience, University of Sussex, Falmer, Brighton, United Kingdom
| | - C N Hall
- School of Psychology and Sussex Neuroscience, University of Sussex, Falmer, Brighton, United Kingdom.
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16
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Schmid F, Conti G, Jenny P, Weber B. The severity of microstrokes depends on local vascular topology and baseline perfusion. eLife 2021; 10:60208. [PMID: 34003107 PMCID: PMC8421069 DOI: 10.7554/elife.60208] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 05/17/2021] [Indexed: 01/26/2023] Open
Abstract
Cortical microinfarcts are linked to pathologies like cerebral amyloid angiopathy and dementia. Despite their relevance for disease progression, microinfarcts often remain undetected and the smallest scale of blood flow disturbance has not yet been identified. We employed blood flow simulations in realistic microvascular networks from the mouse cortex to quantify the impact of single-capillary occlusions. Our simulations reveal that the severity of a microstroke is strongly affected by the local vascular topology and the baseline flow rate in the occluded capillary. The largest changes in perfusion are observed in capillaries with two inflows and two outflows. This specific topological configuration only occurs with a frequency of 8%. The majority of capillaries have one inflow and one outflow and is likely designed to efficiently supply oxygen and nutrients. Taken together, microstrokes bear potential to induce a cascade of local disturbances in the surrounding tissue, which might accumulate and impair energy supply locally.
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Affiliation(s)
- Franca Schmid
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Institute of Fluid Dynamics, ETH Zurich, Zurich, Switzerland
| | - Giulia Conti
- Institute of Fluid Dynamics, ETH Zurich, Zurich, Switzerland
| | - Patrick Jenny
- Institute of Fluid Dynamics, ETH Zurich, Zurich, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland
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17
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Allu SR, Ravotto L, Troxler T, Vinogradov SA. syn-Diarylphthalimidoporphyrins: Effects of Symmetry Breaking on Two-Photon Absorption and Linear Photophysical Properties. J Phys Chem A 2021; 125:2977-2988. [PMID: 33822621 DOI: 10.1021/acs.jpca.1c01652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Aromatically π-extended porphyrins possess exceptionally intense one-photon (1P) and sometimes two-photon (2P) absorption bands, presenting interest for construction of optical imaging probes and photodynamic agents. Here we investigated how breaking the molecular symmetry affects linear and 2PA properties of π-extended porphyrins. First, we developed the synthesis of porphyrins fused with two phthalimide fragments, termed syn-diarylphthalimidoporphyrins (DAPIP). Second, the photophysical properties of H2, Zn, Pd, and Pt DAPIP were measured and compared to those of fully symmetric tetraarylphthalimidoporphyrins (TAPIP). The data were interpreted using DFT/TDDFT calculations and sum-over-states (SOS) formalism. Overall, the picture of 2PA in DAPIP was found to resemble that in centrosymmetric porphyrins, indicating that symmetry breaking, even as significant as by syn-phthalimido-fusion, induces a relatively small perturbation to the porphyrin electronic structure. Collectively, the compact size, versatile synthesis, high 1PA and 2PA cross sections, and bright luminescence make DAPIP valuable chromophores for construction of imaging probes and other bioapplications.
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Affiliation(s)
- Srinivasa Rao Allu
- Department of Biochemistry and Biophysics, Perelman School of Medicine, and Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Luca Ravotto
- Department of Biochemistry and Biophysics, Perelman School of Medicine, and Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Thomas Troxler
- Department of Biochemistry and Biophysics, Perelman School of Medicine, and Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, Perelman School of Medicine, and Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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18
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Tahir W, Kura S, Zhu J, Cheng X, Damseh R, Tadesse F, Seibel A, Lee BS, Lesage F, Sakadžic S, Boas DA, Tian L. Anatomical Modeling of Brain Vasculature in Two-Photon Microscopy by Generalizable Deep Learning. BME FRONTIERS 2021. [DOI: 10.34133/2021/8620932] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Objective and Impact Statement. Segmentation of blood vessels from two-photon microscopy (2PM) angiograms of brains has important applications in hemodynamic analysis and disease diagnosis. Here, we develop a generalizable deep learning technique for accurate 2PM vascular segmentation of sizable regions in mouse brains acquired from multiple 2PM setups. The technique is computationally efficient, thus ideal for large-scale neurovascular analysis. Introduction. Vascular segmentation from 2PM angiograms is an important first step in hemodynamic modeling of brain vasculature. Existing segmentation methods based on deep learning either lack the ability to generalize to data from different imaging systems or are computationally infeasible for large-scale angiograms. In this work, we overcome both these limitations by a method that is generalizable to various imaging systems and is able to segment large-scale angiograms. Methods. We employ a computationally efficient deep learning framework with a loss function that incorporates a balanced binary-cross-entropy loss and total variation regularization on the network’s output. Its effectiveness is demonstrated on experimentally acquired in vivo angiograms from mouse brains of dimensions up to 808×808×702 μm. Results. To demonstrate the superior generalizability of our framework, we train on data from only one 2PM microscope and demonstrate high-quality segmentation on data from a different microscope without any network tuning. Overall, our method demonstrates 10× faster computation in terms of voxels-segmented-per-second and 3× larger depth compared to the state-of-the-art. Conclusion. Our work provides a generalizable and computationally efficient anatomical modeling framework for brain vasculature, which consists of deep learning-based vascular segmentation followed by graphing. It paves the way for future modeling and analysis of hemodynamic response at much greater scales that were inaccessible before.
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Affiliation(s)
- Waleed Tahir
- Department of Electrical and Computer Engineering, Boston University, Boston, MA, USA
| | - Sreekanth Kura
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Jiabei Zhu
- Department of Electrical and Computer Engineering, Boston University, Boston, MA, USA
| | - Xiaojun Cheng
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Rafat Damseh
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada
| | - Fetsum Tadesse
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Alex Seibel
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Blaire S. Lee
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
| | - Frédéric Lesage
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada
| | - Sava Sakadžic
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, USA
| | - David A. Boas
- Department of Electrical and Computer Engineering, Boston University, Boston, MA, USA
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
- Neurophotonics Center, Boston University, Boston, MA, USA
| | - Lei Tian
- Department of Electrical and Computer Engineering, Boston University, Boston, MA, USA
- Neurophotonics Center, Boston University, Boston, MA, USA
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19
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Howarth C, Mishra A, Hall CN. More than just summed neuronal activity: how multiple cell types shape the BOLD response. Philos Trans R Soc Lond B Biol Sci 2021; 376:20190630. [PMID: 33190598 PMCID: PMC7116385 DOI: 10.1098/rstb.2019.0630] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/22/2020] [Indexed: 12/11/2022] Open
Abstract
Functional neuroimaging techniques are widely applied to investigations of human cognition and disease. The most commonly used among these is blood oxygen level-dependent (BOLD) functional magnetic resonance imaging. The BOLD signal occurs because neural activity induces an increase in local blood supply to support the increased metabolism that occurs during activity. This supply usually outmatches demand, resulting in an increase in oxygenated blood in an active brain region, and a corresponding decrease in deoxygenated blood, which generates the BOLD signal. Hence, the BOLD response is shaped by an integration of local oxygen use, through metabolism, and supply, in the blood. To understand what information is carried in BOLD signals, we must understand how several cell types in the brain-local excitatory neurons, inhibitory neurons, astrocytes and vascular cells (pericytes, vascular smooth muscle and endothelial cells), and their modulation by ascending projection neurons-contribute to both metabolism and haemodynamic changes. Here, we review the contributions of each cell type to the regulation of cerebral blood flow and metabolism, and discuss situations where a simplified interpretation of the BOLD response as reporting local excitatory activity may misrepresent important biological phenomena, for example with regards to arousal states, ageing and neurological disease. This article is part of the theme issue 'Key relationships between non-invasive functional neuroimaging and the underlying neuronal activity'.
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Affiliation(s)
- Clare Howarth
- Department of Psychology, University of Sheffield, Sheffield S1 2LT, UK
| | - Anusha Mishra
- Department of Neurology, Jungers Center for Neurosciences Research, and Knight Cardiovascular Institute, Oregon Health and Science University, Portland, OR 97239, USA
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20
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Ravotto L, Meloni SL, Esipova TV, Masunov AE, Anna JM, Vinogradov SA. Three-Photon Spectroscopy of Porphyrins. J Phys Chem A 2020; 124:11038-11050. [PMID: 33337890 DOI: 10.1021/acs.jpca.0c08334] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Recent advances in laser technology have made three-photon (3P) microscopy a real possibility, raising interest in the phenomenon of 3P absorption (3PA). Understanding 3PA of organic chromophores is especially important in view of those imaging applications that rely on exogenous probes, whose optical properties can be manipulated and optimized. Here, we present measurements and theoretical analysis of the degenerate 3PA spectra of several phosphorescent metalloporphyrins, which are used in the construction of biological oxygen probes. The effective 3PA cross sections (σ(3)) of these porphyrins near 1700 nm, a new promising biological optical window, were found to be on the order of 1000 GM3 (1 GM3 = 10-83 cm6 s2), therefore being among the highest values reported to date for organic chromophores. To interpret our data, we developed a qualitative four-state model specific for porphyrins and used it in conjunction with quantitative analysis based on the time-dependent density functional theory (TDDFT)/a posteriori Tamm-Dancoff approximation (ATDA)/sum-over-states (SOS) formalism. The analysis revealed that B (Soret) state plays a key role in the enhancement of 3PA of porphyrins in the Q band region, while the low-lying two-photon (2P)-allowed gerade states interfere negatively and diminish the 3PA strength. This study features the first systematic examination of 3PA properties of porphyrins, suggesting ways to improve their performance and optimize them for imaging and other biomedical applications.
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Affiliation(s)
- Luca Ravotto
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.,Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Stephen L Meloni
- Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Tatiana V Esipova
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.,Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Artëm E Masunov
- NanoScience Technology Center, Department of Chemistry, and School of Modeling, Simulation and Training, University of Central Florida, Orlando, Florida 32826, United States.,National Nuclear Research University MEPhI, Kashirskoye Shosse 31, Moscow 115409, Russia.,South Ural State University, Lenin Pr. 76, Chelyabinsk 454080, Russia
| | - Jessica M Anna
- Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.,Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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21
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Tahir W, Kura S, Zhu J, Cheng X, Damseh R, Tadesse F, Seibel A, Lee BS, Lesage F, Sakadžic S, Boas DA, Tian L. Anatomical Modeling of Brain Vasculature in Two-Photon Microscopy by Generalizable Deep Learning. BME FRONTIERS 2020; 2020:8620932. [PMID: 37849965 PMCID: PMC10521669 DOI: 10.34133/2020/8620932] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 11/12/2020] [Indexed: 10/19/2023] Open
Abstract
Objective and Impact Statement. Segmentation of blood vessels from two-photon microscopy (2PM) angiograms of brains has important applications in hemodynamic analysis and disease diagnosis. Here, we develop a generalizable deep learning technique for accurate 2PM vascular segmentation of sizable regions in mouse brains acquired from multiple 2PM setups. The technique is computationally efficient, thus ideal for large-scale neurovascular analysis. Introduction. Vascular segmentation from 2PM angiograms is an important first step in hemodynamic modeling of brain vasculature. Existing segmentation methods based on deep learning either lack the ability to generalize to data from different imaging systems or are computationally infeasible for large-scale angiograms. In this work, we overcome both these limitations by a method that is generalizable to various imaging systems and is able to segment large-scale angiograms. Methods. We employ a computationally efficient deep learning framework with a loss function that incorporates a balanced binary-cross-entropy loss and total variation regularization on the network's output. Its effectiveness is demonstrated on experimentally acquired in vivo angiograms from mouse brains of dimensions up to 808 × 808 × 702 μ m . Results. To demonstrate the superior generalizability of our framework, we train on data from only one 2PM microscope and demonstrate high-quality segmentation on data from a different microscope without any network tuning. Overall, our method demonstrates 10× faster computation in terms of voxels-segmented-per-second and 3× larger depth compared to the state-of-the-art. Conclusion. Our work provides a generalizable and computationally efficient anatomical modeling framework for brain vasculature, which consists of deep learning-based vascular segmentation followed by graphing. It paves the way for future modeling and analysis of hemodynamic response at much greater scales that were inaccessible before.
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Affiliation(s)
- Waleed Tahir
- Department of Electrical and Computer Engineering, Boston University, Boston, MA, USA
| | - Sreekanth Kura
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Jiabei Zhu
- Department of Electrical and Computer Engineering, Boston University, Boston, MA, USA
| | - Xiaojun Cheng
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Rafat Damseh
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada
| | - Fetsum Tadesse
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Alex Seibel
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Blaire S. Lee
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
| | - Frédéric Lesage
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada
| | - Sava Sakadžic
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, USA
| | - David A. Boas
- Department of Electrical and Computer Engineering, Boston University, Boston, MA, USA
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
- Neurophotonics Center, Boston University, Boston, MA, USA
| | - Lei Tian
- Department of Electrical and Computer Engineering, Boston University, Boston, MA, USA
- Neurophotonics Center, Boston University, Boston, MA, USA
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22
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Mizukami K, Katano A, Shiozaki S, Yoshihara T, Goda N, Tobita S. In vivo O 2 imaging in hepatic tissues by phosphorescence lifetime imaging microscopy using Ir(III) complexes as intracellular probes. Sci Rep 2020; 10:21053. [PMID: 33273499 PMCID: PMC7713648 DOI: 10.1038/s41598-020-76878-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 10/28/2020] [Indexed: 01/14/2023] Open
Abstract
Phosphorescence lifetime imaging microscopy (PLIM) combined with an oxygen (O2)-sensitive luminescent probe allows for high-resolution O2 imaging of living tissues. Herein, we present phosphorescent Ir(III) complexes, (btp)2Ir(acac-DM) (Ir-1) and (btp-OH)3Ir (Ir-2), as useful O2 probes for PLIM measurement. These small-molecule probes were efficiently taken up into cultured cells and accumulated in specific organelles. Their excellent cell-permeable properties allowed for efficient staining of three-dimensional cell spheroids, and thereby phosphorescence lifetime measurements enabled the evaluation of the O2 level and distribution in spheroids, including the detection of alterations in O2 levels by metabolic stimulation with an effector. We took PLIM images of hepatic tissues of living mice by intravenously administrating these probes. The PLIM images clearly visualized the O2 gradient in hepatic lobules with cellular-level resolution, and the O2 levels were derived based on calibration using cultured cells; the phosphorescence lifetime of Ir-1 gave reasonable O2 levels, whereas Ir-2 exhibited much lower O2 levels. Intravenous administration of NH4Cl to mice caused the hepatic tissues to experience hypoxia, presumably due to O2 consumption to produce ATP required for ammonia detoxification, suggesting that the metabolism of the probe molecule might affect liver O2 levels.
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Affiliation(s)
- Kiichi Mizukami
- Department of Chemistry and Chemical Biology, School of Science and Technology, Gunma University, Kiryu, Gunma, 376-8515, Japan
| | - Ayaka Katano
- Department of Chemistry and Chemical Biology, School of Science and Technology, Gunma University, Kiryu, Gunma, 376-8515, Japan
| | - Shuichi Shiozaki
- Department of Chemistry and Chemical Biology, School of Science and Technology, Gunma University, Kiryu, Gunma, 376-8515, Japan
| | - Toshitada Yoshihara
- Department of Chemistry and Chemical Biology, School of Science and Technology, Gunma University, Kiryu, Gunma, 376-8515, Japan.
| | - Nobuhito Goda
- Department of Life Science and Medical BioScience, School of Advanced Science and Engineering, Waseda University, Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan
| | - Seiji Tobita
- Department of Chemistry and Chemical Biology, School of Science and Technology, Gunma University, Kiryu, Gunma, 376-8515, Japan.
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23
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Mini-review: Perfluorocarbons, Oxygen Transport, and Microcirculation in Low Flow States: in Vivo and in Vitro Studies. Shock 2020; 52:19-27. [PMID: 28930919 DOI: 10.1097/shk.0000000000000994] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The in vivo study of microvascular oxygen transport requires accurate and challenging measurements of several mass transfer parameters. Although recommended, blood flow and oxygenation are typically not measured in many studies where treatments for ischemia are tested. Therefore, the aim of this communication is to briefly review cardinal aspects of oxygen transport, and the effects of perfluorocarbon (PFC) treatment on blood flow and oxygenation based mostly on studies performed in our laboratory. As physiologically relevant events in oxygen transport take place at the microvascular level, we implemented the phosphorescence quenching technique coupled with noninvasive intravital videomicroscopy for quantitative evaluation of these events in vivo. Rodent experimental models and various approaches have been used to induce ischemia, including hemorrhage, micro- and macroembolism, and microvessel occlusion. Measurements show decrease in microvascular blood flow as well as intravascular and tissue oxygen partial pressure (PO2) after these procedures. To minimize or reverse the effects of ischemia and hypoxia, artificial oxygen carriers such as different PFCs were tested. Well-defined endpoints such as blood flow and tissue PO2 were measured because they have significant effect on tissue survival and outcome. In several cases, enhancement of flow and oxygenation could be demonstrated. Similar results were found in vitro: PFC emulsion mixed with blood (from healthy donors and sickle cell disease patients) enhanced oxygen transport. In summary, PFCs may provide beneficial effects in these models by mechanisms at the microvascular level including facilitated diffusion and bubble reabsorption leading to improved blood flow and oxygenation.
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24
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Faivre A, Scholz CC, de Seigneux S. Hypoxia in chronic kidney disease: towards a paradigm shift? Nephrol Dial Transplant 2020; 36:1782-1790. [PMID: 33895835 DOI: 10.1093/ndt/gfaa091] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Indexed: 11/15/2022] Open
Abstract
Chronic kidney disease (CKD) is defined as an alteration of kidney structure and/or function lasting for >3 months [1]. CKD affects 10% of the general adult population and is responsible for large healthcare costs [2]. Since the end of the last century, the role of hypoxia in CKD progression has controversially been discussed. To date, there is evidence of the presence of hypoxia in late-stage renal disease, but we lack time-course evidence, stage correlation and also spatial co-localization with fibrotic lesions to ensure its causative role. The classical view of hypoxia in CKD progression is that it is caused by peritubular capillary alterations, renal anaemia and increased oxygen consumption regardless of the primary injury. In this classical view, hypoxia is assumed to further induce pro-fibrotic and pro-inflammatory responses, as well as oxidative stress, leading to CKD worsening as part of a vicious circle. However, recent investigations tend to question this paradigm, and both the presence of hypoxia and its role in CKD progression are still not clearly demonstrated. Hypoxia-inducible factor (HIF) is the main transcriptional regulator of the hypoxia response. Genetic HIF modulation leads to variable effects on CKD progression in different murine models. In contrast, pharmacological modulation of the HIF pathway [i.e. by HIF hydroxylase inhibitors (HIs)] appears to be generally protective against fibrosis progression experimentally. We here review the existing literature on the role of hypoxia, the HIF pathway and HIF HIs in CKD progression and summarize the evidence that supports or rejects the hypoxia hypothesis, respectively.
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Affiliation(s)
- Anna Faivre
- Department of Cell physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Carsten C Scholz
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Centre of Competence in Research "Kidney.CH", Zurich, Switzerland
| | - Sophie de Seigneux
- Department of Cell physiology and Metabolism, University of Geneva, Geneva, Switzerland.,National Centre of Competence in Research "Kidney.CH", Zurich, Switzerland.,Department of Medicine, Service of Nephrology, Geneva University Hospitals, Geneva, Switzerland
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25
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Li B, Ohtomo R, Thunemann M, Adams SR, Yang J, Fu B, Yaseen MA, Ran C, Polimeni JR, Boas DA, Devor A, Lo EH, Arai K, Sakadžić S. Two-photon microscopic imaging of capillary red blood cell flux in mouse brain reveals vulnerability of cerebral white matter to hypoperfusion. J Cereb Blood Flow Metab 2020; 40:501-512. [PMID: 30829101 PMCID: PMC7026840 DOI: 10.1177/0271678x19831016] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 01/19/2019] [Accepted: 01/21/2019] [Indexed: 01/15/2023]
Abstract
Despite the importance of understanding the regulation of microvascular blood flow in white matter, no data on subcortical capillary blood flow parameters are available, largely due to the lack of appropriate imaging methods. To address this knowledge gap, we employed two-photon microscopy using a far-red fluorophore Alexa680 and photon-counting detection to measure capillary red blood cell (RBC) flux in both cerebral gray and white matter, in isoflurane-anesthetized mice. We have found that in control animals, baseline capillary RBC flux in the white matter was significantly higher than in the adjacent cerebral gray matter. In response to mild hypercapnia, RBC flux in the white matter exhibited significantly smaller fractional increase than in the gray matter. Finally, during global cerebral hypoperfusion, RBC flux in the white matter was reduced significantly in comparison to the controls, while RBC flux in the gray matter was preserved. Our results suggest that blood flow in the white matter may be less efficiently regulated when challenged by physiological perturbations as compared to the gray matter. Importantly, the blood flow in the white matter may be more susceptible to hypoperfusion than in the gray matter, potentially exacerbating the white matter deterioration in brain conditions involving global cerebral hypoperfusion.
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Affiliation(s)
- Baoqiang Li
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Ryo Ohtomo
- Departments of Radiology and Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Martin Thunemann
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Stephen R Adams
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
| | - Jing Yang
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Buyin Fu
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Mohammad A Yaseen
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Chongzhao Ran
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Jonathan R Polimeni
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - David A Boas
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Anna Devor
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
- Department of Radiology, University of California San Diego, La Jolla, CA, USA
| | - Eng H Lo
- Departments of Radiology and Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Ken Arai
- Departments of Radiology and Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
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26
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Zhang Q, Roche M, Gheres KW, Chaigneau E, Kedarasetti RT, Haselden WD, Charpak S, Drew PJ. Cerebral oxygenation during locomotion is modulated by respiration. Nat Commun 2019; 10:5515. [PMID: 31797933 PMCID: PMC6893036 DOI: 10.1038/s41467-019-13523-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 11/12/2019] [Indexed: 12/17/2022] Open
Abstract
In the brain, increased neural activity is correlated with increases of cerebral blood flow and tissue oxygenation. However, how cerebral oxygen dynamics are controlled in the behaving animal remains unclear. We investigated to what extent cerebral oxygenation varies during locomotion. We measured oxygen levels in the cortex of awake, head-fixed mice during locomotion using polarography, spectroscopy, and two-photon phosphorescence lifetime measurements of oxygen sensors. We find that locomotion significantly and globally increases cerebral oxygenation, specifically in areas involved in locomotion, as well as in the frontal cortex and the olfactory bulb. The oxygenation increase persists when neural activity and functional hyperemia are blocked, occurred both in the tissue and in arteries feeding the brain, and is tightly correlated with respiration rate and the phase of respiration cycle. Thus, breathing rate is a key modulator of cerebral oxygenation and should be monitored during hemodynamic imaging, such as in BOLD fMRI.
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Affiliation(s)
- Qingguang Zhang
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA
| | - Morgane Roche
- Institut National de la Santé et de la Recherche Médicale, U1128, Paris, France.,Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris, France
| | - Kyle W Gheres
- Graduate Program in Molecular Cellular and Integrative Biosciences, The Pennsylvania State University, University Park, PA, USA
| | - Emmanuelle Chaigneau
- Institut National de la Santé et de la Recherche Médicale, U1128, Paris, France.,Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris, France
| | - Ravi T Kedarasetti
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA
| | - William D Haselden
- Medical Scientist Training Program and Neuroscience Graduate Program, The Pennsylvania State University, University Park, PA, USA
| | - Serge Charpak
- Institut National de la Santé et de la Recherche Médicale, U1128, Paris, France.,Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris, France
| | - Patrick J Drew
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA. .,Department of Neurosurgery and Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA, USA.
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27
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Damseh R, Pouliot P, Gagnon L, Sakadzic S, Boas D, Cheriet F, Lesage F. Automatic Graph-Based Modeling of Brain Microvessels Captured With Two-Photon Microscopy. IEEE J Biomed Health Inform 2019; 23:2551-2562. [PMID: 30507542 PMCID: PMC6546554 DOI: 10.1109/jbhi.2018.2884678] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Graph models of cerebral vasculature derived from two-photon microscopy have shown to be relevant to study brain microphysiology. Automatic graphing of these microvessels remain problematic due to the vascular network complexity and two-photon sensitivity limitations with depth. In this paper, we propose a fully automatic processing pipeline to address this issue. The modeling scheme consists of a fully-convolution neural network to segment microvessels, a three-dimensional surface model generator, and a geometry contraction algorithm to produce graphical models with a single connected component. Based on a quantitative assessment using NetMets metrics, at a tolerance of 60 μm, false negative and false positive geometric error 19 rates are 3.8% and 4.2%, respectively, whereas false nega- 20 tive and false positive topological error rates are 6.1% and 4.5%, respectively. Our qualitative evaluation confirms the efficiency of our scheme in generating useful and accurate graphical models.
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Affiliation(s)
- Rafat Damseh
- Institute of Biomedical Engineering, École Polytechnique de Montréal, Montreal, QC, Canada
| | - Philippe Pouliot
- Department of Electrical Engineering, École Polytechnique de Montréal, Montreal, QC, Canada
- Research Centre, Montreal Hearth Institute, Montreal, QC, Canada
| | - Louis Gagnon
- Physics Department, Université Laval, Quebec, QC, Canada
| | - Sava Sakadzic
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - David Boas
- Neurophotonics Center, Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Farida Cheriet
- Department of Computer and Software Engineering, École Polytechnique de Montréal, Montreal, QC, Canada
| | - Frederic Lesage
- Institute of Biomedical Engineering, École Polytechnique de Montréal, Montreal, QC, Canada
- Department of Electrical Engineering, École Polytechnique de Montréal, Montreal, QC, Canada
- Research Centre, Montreal Hearth Institute, Montreal, QC, Canada
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28
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Schilling K, El Khatib M, Plunkett S, Xue J, Xia Y, Vinogradov SA, Brown E, Zhang X. Electrospun Fiber Mesh for High-Resolution Measurements of Oxygen Tension in Cranial Bone Defect Repair. ACS APPLIED MATERIALS & INTERFACES 2019; 11:33548-33558. [PMID: 31436082 PMCID: PMC6916729 DOI: 10.1021/acsami.9b08341] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Tissue oxygenation is one of the key determining factors in bone repair and bone tissue engineering. Adequate tissue oxygenation is essential for survival and differentiation of the bone-forming cells and ultimately the success of bone tissue regeneration. Two-photon phosphorescence lifetime microscopy (2PLM) has been successfully applied in the past to image oxygen distributions in tissue with high spatial resolution. However, delivery of phosphorescent probes into avascular compartments, such as those formed during early bone defect healing, poses significant problems. Here, we report a multifunctional oxygen-reporting fibrous matrix fabricated through encapsulation of a hydrophilic oxygen-sensitive, two-photon excitable phosphorescent probe, PtP-C343, in the core of fibers during coaxial electrospinning. The oxygen-sensitive fibers support bone marrow stromal cell growth and differentiation and at the same time enable real-time high-resolution probing of partial pressures of oxygen via 2PLM. The hydrophilicity of the probe facilitates its gradual release into the nearby microenvironment, allowing fibers to act as a vehicle for probe delivery into the healing tissue. In conjunction with a cranial defect window chamber model, which permits simultaneous imaging of the bone and neovasculature in vivo via two-photon laser scanning microscopy, the oxygen-reporting fibers provide a useful tool for minimally invasive, high-resolution, real-time 3D mapping of tissue oxygenation during bone defect healing, facilitating studies aimed at understanding the healing process and advancing design of tissue-engineered constructs for enhanced bone repair and regeneration.
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Affiliation(s)
- Kevin Schilling
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14620, USA
- Center for Musculoskeletal Research, University of Rochester, School of Medicine and Dentistry, Rochester, NY 146421, USA
| | - Mirna El Khatib
- Departments of Biochemistry and Biophysics and of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Shane Plunkett
- Departments of Biochemistry and Biophysics and of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jiajia Xue
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
| | - Younan Xia
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
| | - Sergei A. Vinogradov
- Departments of Biochemistry and Biophysics and of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
- Corresponding authors contact information: Xinping Zhang, The Center for Musculoskeletal Research, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA, ; Edward Brown, Department of Biomedical Engineering, University of Rochester, Goergen Hall Box 270168Rochester, NY 14642, USA, ; Sergei A. Vinogradov, Department of Biochemistry and Biophysics, Perelman School of Medicine, Department of Chemistry, School of Arts and Sciences University of Pennsylvania Philadelphia, PA 19104,
| | - Edward Brown
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14620, USA
- Corresponding authors contact information: Xinping Zhang, The Center for Musculoskeletal Research, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA, ; Edward Brown, Department of Biomedical Engineering, University of Rochester, Goergen Hall Box 270168Rochester, NY 14642, USA, ; Sergei A. Vinogradov, Department of Biochemistry and Biophysics, Perelman School of Medicine, Department of Chemistry, School of Arts and Sciences University of Pennsylvania Philadelphia, PA 19104,
| | - Xinping Zhang
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14620, USA
- Center for Musculoskeletal Research, University of Rochester, School of Medicine and Dentistry, Rochester, NY 146421, USA
- Corresponding authors contact information: Xinping Zhang, The Center for Musculoskeletal Research, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA, ; Edward Brown, Department of Biomedical Engineering, University of Rochester, Goergen Hall Box 270168Rochester, NY 14642, USA, ; Sergei A. Vinogradov, Department of Biochemistry and Biophysics, Perelman School of Medicine, Department of Chemistry, School of Arts and Sciences University of Pennsylvania Philadelphia, PA 19104,
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29
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Schmid F, Barrett MJP, Obrist D, Weber B, Jenny P. Red blood cells stabilize flow in brain microvascular networks. PLoS Comput Biol 2019; 15:e1007231. [PMID: 31469820 PMCID: PMC6750893 DOI: 10.1371/journal.pcbi.1007231] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 09/18/2019] [Accepted: 07/01/2019] [Indexed: 12/28/2022] Open
Abstract
Capillaries are the prime location for oxygen and nutrient exchange in all tissues. Despite their fundamental role, our knowledge of perfusion and flow regulation in cortical capillary beds is still limited. Here, we use in vivo measurements and blood flow simulations in anatomically accurate microvascular network to investigate the impact of red blood cells (RBCs) on microvascular flow. Based on these in vivo and in silico experiments, we show that the impact of RBCs leads to a bias toward equating the values of the outflow velocities at divergent capillary bifurcations, for which we coin the term “well-balanced bifurcations”. Our simulation results further reveal that hematocrit heterogeneity is directly caused by the RBC dynamics, i.e. by their unequal partitioning at bifurcations and their effect on vessel resistance. These results provide the first in vivo evidence of the impact of RBC dynamics on the flow field in the cortical microvasculature. By structural and functional analyses of our blood flow simulations we show that capillary diameter changes locally alter flow and RBC distribution. A dilation of 10% along a vessel length of 100 μm increases the flow on average by 21% in the dilated vessel downstream a well-balanced bifurcation. The number of RBCs rises on average by 27%. Importantly, RBC up-regulation proves to be more effective the more balanced the outflow velocities at the upstream bifurcation are. Taken together, we conclude that diameter changes at capillary level bear potential to locally change the flow field and the RBC distribution. Moreover, our results suggest that the balancing of outflow velocities contributes to the robustness of perfusion. Based on our in silico results, we anticipate that the bi-phasic nature of blood and small-scale regulations are essential for a well-adjusted oxygen and energy substrate supply. Glucose and oxygen are key energy sources of the brain. As energy storage capabilities are limited in the brain, a continuous supply of oxygen and glucose via the bloodstream is crucial for the brain’s functioning. The bulk of discharge occurs at the level of capillaries, which are the smallest and most frequent vessels of the cortical vasculature. Nonetheless, our understanding of perfusion and topology of the capillary bed is still limited. Here, we use in vivo two-photon based blood flow measurements and numerical simulations in large realistic microvascular networks to study the flow in the cortical microvasculature. Our results reveal that the impact of red blood cells enhances the robustness of microvascular perfusion and increases the heterogeneity in red blood cell distribution. It is well established that higher neuronal activity leads to an increase in blood flow. However, the precise regulation mechanisms and their spatial extent remain largely unknown. We show that small-scale regulations locally alter flow and red blood cell distribution. We suggest that these mechanisms are key for an efficient and flexible circulatory system. Moreover, our results reveal a novel role of the bi-phasic nature of blood.
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Affiliation(s)
- Franca Schmid
- Institute of Fluid Dynamics, ETH Zurich, Sonneggstrasse 3, Zurich, Switzerland
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, Zurich, Switzerland
- * E-mail:
| | - Matthew J. P. Barrett
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, Winterthurerstrasse 190, Zurich, Switzerland
| | - Dominik Obrist
- ARTORG Center for Biomedical Engineering Research, University of Bern, Murtenstrasse 50, Bern, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, Winterthurerstrasse 190, Zurich, Switzerland
| | - Patrick Jenny
- Institute of Fluid Dynamics, ETH Zurich, Sonneggstrasse 3, Zurich, Switzerland
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30
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Atherosclerosis is associated with a decrease in cerebral microvascular blood flow and tissue oxygenation. PLoS One 2019; 14:e0221547. [PMID: 31469849 PMCID: PMC6716780 DOI: 10.1371/journal.pone.0221547] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 08/11/2019] [Indexed: 02/07/2023] Open
Abstract
Chronic atherosclerosis may cause cerebral hypoperfusion and inadequate brain oxygenation, contributing to the progression of cognitive decline. In this study, we exploited two-photon phosphorescence lifetime microscopy to measure the absolute partial pressure of oxygen (PO2) in cortical tissue in both young and old LDLR-/-, hApoB100+/+ mice, spontaneously developing atherosclerosis with age. Capillary red-blood-cell (RBC) speed, flux, hematocrit and capillary diameter were also measured by two-photon imaging of FITC-labelled blood plasma. Our results show positive correlations between RBC speed, flux, diameter and capillary-adjacent tissue PO2. When compared to the young mice, we observed lower tissue PO2, lower RBC speed and flux, and smaller capillary diameter in the old atherosclerotic mice. The old mice also exhibited a higher spatial heterogeneity of tissue PO2, and RBC speed and flux, suggesting a less efficient oxygen extraction.
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31
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Roche M, Chaigneau E, Rungta RL, Boido D, Weber B, Charpak S. In vivo imaging with a water immersion objective affects brain temperature, blood flow and oxygenation. eLife 2019; 8:47324. [PMID: 31397668 PMCID: PMC6707784 DOI: 10.7554/elife.47324] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 08/08/2019] [Indexed: 01/22/2023] Open
Abstract
Previously, we reported the first oxygen partial pressure (Po2) measurements in the brain of awake mice, by performing two-photon phosphorescence lifetime microscopy at micrometer resolution (Lyons et al., 2016). However, this study disregarded that imaging through a cranial window lowers brain temperature, an effect capable of affecting cerebral blood flow, the properties of the oxygen sensors and thus Po2 measurements. Here, we show that in awake mice chronically implanted with a glass window over a craniotomy or a thinned-skull surface, the postsurgical decrease of brain temperature recovers within a few days. However, upon imaging with a water immersion objective at room temperature, brain temperature decreases by ~2-3°C, causing drops in resting capillary blood flow, capillary Po2, hemoglobin saturation, and tissue Po2. These adverse effects are corrected by heating the immersion objective or avoided by imaging through a dry air objective, thereby revealing the physiological values of brain oxygenation.
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Affiliation(s)
- Morgane Roche
- Laboratory of Neurophysiology and New Microscopy, INSERM U1128, Université Paris Descartes, Paris, France
| | - Emmanuelle Chaigneau
- Laboratory of Neurophysiology and New Microscopy, INSERM U1128, Université Paris Descartes, Paris, France
| | - Ravi L Rungta
- Laboratory of Neurophysiology and New Microscopy, INSERM U1128, Université Paris Descartes, Paris, France
| | - Davide Boido
- Laboratory of Neurophysiology and New Microscopy, INSERM U1128, Université Paris Descartes, Paris, France
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland
| | - Serge Charpak
- Laboratory of Neurophysiology and New Microscopy, INSERM U1128, Université Paris Descartes, Paris, France
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32
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Drew PJ. Vascular and neural basis of the BOLD signal. Curr Opin Neurobiol 2019; 58:61-69. [PMID: 31336326 DOI: 10.1016/j.conb.2019.06.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 06/22/2019] [Indexed: 12/26/2022]
Abstract
Neural activity in the brain is usually coupled to increases in local cerebral blood flow, leading to the increase in oxygenation that generates the BOLD fMRI signal. Recent work has begun to elucidate the vascular and neural mechanisms underlying the BOLD signal. The dilatory response is distributed throughout the vascular network. Arteries actively dilate within a second following neural activity increases, while venous distensions are passive and have a time course that last tens of seconds. Vasodilation, and thus local blood flow, is controlled by the activity of both neurons and astrocytes via multiple different pathways. The relationship between sensory-driven neural activity and the vascular dynamics in sensory areas are well-captured with a linear convolution model. However, depending on the behavioral state or brain region, the coupling between neural activity and hemodynamic signals can be weak or even inverted.
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Affiliation(s)
- Patrick J Drew
- Departments of Engineering Science and Mechanics, Biomedical Engineering and Neurosurgery, Pennsylvania State University, University Park, PA 16802, United States.
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33
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Li B, Esipova TV, Sencan I, Kılıç K, Fu B, Desjardins M, Moeini M, Kura S, Yaseen MA, Lesage F, Østergaard L, Devor A, Boas DA, Vinogradov SA, Sakadžić S. More homogeneous capillary flow and oxygenation in deeper cortical layers correlate with increased oxygen extraction. eLife 2019; 8:42299. [PMID: 31305237 PMCID: PMC6636997 DOI: 10.7554/elife.42299] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 07/01/2019] [Indexed: 01/01/2023] Open
Abstract
Our understanding of how capillary blood flow and oxygen distribute across cortical layers to meet the local metabolic demand is incomplete. We addressed this question by using two-photon imaging of resting-state microvascular oxygen partial pressure (PO2) and flow in the whisker barrel cortex in awake mice. Our measurements in layers I-V show that the capillary red-blood-cell flux and oxygenation heterogeneity, and the intracapillary resistance to oxygen delivery, all decrease with depth, reaching a minimum around layer IV, while the depth-dependent oxygen extraction fraction is increased in layer IV, where oxygen demand is presumably the highest. Our findings suggest that more homogeneous distribution of the physiological observables relevant to oxygen transport to tissue is an important part of the microvascular network adaptation to local brain metabolism. These results will inform the biophysical models of layer-specific cerebral oxygen delivery and consumption and improve our understanding of the diseases that affect cerebral microcirculation.
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Affiliation(s)
- Baoqiang Li
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
| | - Tatiana V Esipova
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, United States.,Department of Chemistry, University of Pennsylvania, Philadelphia, United States
| | - Ikbal Sencan
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
| | - Kıvılcım Kılıç
- Department of Neurosciences, University of California, San Diego, La Jolla, United States
| | - Buyin Fu
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
| | - Michele Desjardins
- Department of Radiology, University of California, San Diego, La Jolla, United States
| | - Mohammad Moeini
- Institute of Biomedical Engineering, École Polytechnique de Montréal, Montréal, Canada.,Research Centre, Montreal Heart Institute, Montréal, Canada
| | - Sreekanth Kura
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
| | - Mohammad A Yaseen
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
| | - Frederic Lesage
- Institute of Biomedical Engineering, École Polytechnique de Montréal, Montréal, Canada.,Research Centre, Montreal Heart Institute, Montréal, Canada
| | - Leif Østergaard
- Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Anna Devor
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States.,Department of Neurosciences, University of California, San Diego, La Jolla, United States.,Department of Radiology, University of California, San Diego, La Jolla, United States
| | - David A Boas
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States.,Department of Biomedical Engineering, Boston University, Boston, United States
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, United States.,Department of Chemistry, University of Pennsylvania, Philadelphia, United States
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
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34
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Assessment of cerebral and renal autoregulation using near-infrared spectroscopy under normal, hypovolaemic and postfluid resuscitation conditions in a swine model. Eur J Anaesthesiol 2019; 36:531-540. [DOI: 10.1097/eja.0000000000001021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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35
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Chaigneau E, Roche M, Charpak S. Unbiased Analysis Method for Measurement of Red Blood Cell Size and Velocity With Laser Scanning Microscopy. Front Neurosci 2019; 13:644. [PMID: 31316334 PMCID: PMC6610068 DOI: 10.3389/fnins.2019.00644] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 06/05/2019] [Indexed: 12/28/2022] Open
Abstract
Two-photon laser scanning microscopy is widely used to measure blood hemodynamics in brain blood vessels. Still, the algorithms used so far to extract red blood cell (RBC) size and velocity from line-scan acquisitions have ignored the extent to which scanning speed influences the measurements. Here, we used a theoretical approach that takes into account the velocity and direction of both scanning mirrors and RBCs during acquisition to provide an algorithm that measures the real RBC size and velocity. We validate our approach in brain vessels of anesthetized mice, and demonstrate that it corrects online measurement errors that can reach several 10s of percent as well as data previously acquired. To conclude, our analysis allows unbiased comparisons of blood hemodynamic parameters from brain capillaries and large vessels in control and pathological animal models.
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Affiliation(s)
| | | | - Serge Charpak
- INSERM U1128, Laboratory of Neurophysiology and New Microscopy, Université Paris Descartes, Paris, France
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36
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Francis AT, Berry K, Thomas EC, Hill AH, Fu D. In Vitro Quantification of Single Red Blood Cell Oxygen Saturation by Femtosecond Transient Absorption Microscopy. J Phys Chem Lett 2019; 10:3312-3317. [PMID: 31141669 DOI: 10.1021/acs.jpclett.9b01116] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Hemoglobin, the oxygen carrying protein, ferries nearly all bodily oxygen from the lungs to cells and tissues in need. Blood oxygen saturation (sO2) thus plays an important role in maintaining energy homeostasis throughout the body. Clinical and research tools have been developed to monitor sO2 at a wide range of temporal and spatial scales. However, real-time quantification of sO2 at single red blood cell (RBC) resolution remains challenging. Such capability is critically important to study energy metabolism in heterogeneous tissues including brain and tumor tissue. In this work, we develop a ratiometric transient absorption microscopy technique to image hemoglobin sO2. By exploiting differences in transient lifetime kinetics between oxyhemoglobin and deoxyhemoglobin, we directly quantified the sO2 of single RBCs in real-time without the need for injection of exogenous agents. This simple and high-speed nonlinear optical imaging technique is well suited for in vitro and in vivo quantification of sO2.
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Affiliation(s)
- Andrew T Francis
- Department of Chemistry , University of Washington , Seattle , Washington 98195 , United States
| | - Kyla Berry
- Department of Chemistry , University of Washington , Seattle , Washington 98195 , United States
| | - Elena C Thomas
- Department of Chemistry , University of Washington , Seattle , Washington 98195 , United States
| | - Andrew H Hill
- Department of Chemistry , University of Washington , Seattle , Washington 98195 , United States
| | - Dan Fu
- Department of Chemistry , University of Washington , Seattle , Washington 98195 , United States
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37
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Schneider J, Berndt N, Papageorgiou IE, Maurer J, Bulik S, Both M, Draguhn A, Holzhütter HG, Kann O. Local oxygen homeostasis during various neuronal network activity states in the mouse hippocampus. J Cereb Blood Flow Metab 2019; 39:859-873. [PMID: 29099662 PMCID: PMC6501513 DOI: 10.1177/0271678x17740091] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 10/02/2017] [Indexed: 12/14/2022]
Abstract
Cortical information processing comprises various activity states emerging from timed synaptic excitation and inhibition. However, the underlying energy metabolism is widely unknown. We determined the cerebral metabolic rate of oxygen (CMRO2) along a tissue depth of <0.3 mm in the hippocampal CA3 region during various network activities, including gamma oscillations and sharp wave-ripples that occur during wakefulness and sleep. These physiological states associate with sensory perception and memory formation, and critically depend on perisomatic GABA inhibition. Moreover, we modelled vascular oxygen delivery based on quantitative microvasculature analysis. (1) Local CMRO2 was highest during gamma oscillations (3.4 mM/min), medium during sharp wave-ripples, asynchronous activity and isoflurane application (2.0-1.6 mM/min), and lowest during tetrodotoxin application (1.4 mM/min). (2) Energy expenditure of axonal and synaptic signaling accounted for >50% during gamma oscillations. (3) CMRO2 positively correlated with number and synchronisation of activated synapses, and neural multi-unit activity. (4) The median capillary distance was 44 µm. (5) The vascular oxygen partial pressure of 33 mmHg was needed to sustain oxidative phosphorylation during gamma oscillations. We conclude that gamma oscillations featuring high energetics require a hemodynamic response to match oxygen consumption of respiring mitochondria, and that perisomatic inhibition significantly contributes to the brain energy budget.
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Affiliation(s)
- Justus Schneider
- Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
| | - Nikolaus Berndt
- Computational Systems Biochemistry, Institute of Biochemistry, Charité–Universitätsmedizin Berlin, Berlin, Germany
| | - Ismini E Papageorgiou
- Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
| | - Jana Maurer
- Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
| | - Sascha Bulik
- Computational Systems Biochemistry, Institute of Biochemistry, Charité–Universitätsmedizin Berlin, Berlin, Germany
| | - Martin Both
- Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
| | - Andreas Draguhn
- Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
| | - Hermann-Georg Holzhütter
- Computational Systems Biochemistry, Institute of Biochemistry, Charité–Universitätsmedizin Berlin, Berlin, Germany
| | - Oliver Kann
- Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
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38
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Esipova TV, Barrett MJP, Erlebach E, Masunov AE, Weber B, Vinogradov SA. Oxyphor 2P: A High-Performance Probe for Deep-Tissue Longitudinal Oxygen Imaging. Cell Metab 2019; 29:736-744.e7. [PMID: 30686745 PMCID: PMC6402963 DOI: 10.1016/j.cmet.2018.12.022] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 10/22/2018] [Accepted: 12/26/2018] [Indexed: 01/09/2023]
Abstract
Quantitative imaging of oxygen distributions in tissue can provide invaluable information about metabolism in normal and diseased states. Two-photon phosphorescence lifetime microscopy (2PLM) has been developed to perform measurements of oxygen in vivo with micron-scale resolution in 3D; however, the method's potential has not yet been fully realized due to the limitations of current phosphorescent probe technology. Here, we report a new sensor, Oxyphor 2P, that enables oxygen microscopy twice as deep (up to 600 μm below the tissue surface) and with ∼60 times higher speed than previously possible. Oxyphor 2P allows longitudinal oxygen measurements without having to inject the probe directly into the imaged region. As proof of principle, we monitored oxygen dynamics for days following micro-stroke induced by occlusion of a single capillary in the mouse brain. Oxyphor 2P opens up new possibilities for studies of tissue metabolic states using 2PLM in a wide range of biomedical research areas.
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Affiliation(s)
- Tatiana V Esipova
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Matthew J P Barrett
- Institute of Pharmacology and Toxicology, University of Zurich, Zürich 8057, Switzerland
| | - Eva Erlebach
- Institute of Pharmacology and Toxicology, University of Zurich, Zürich 8057, Switzerland; Neuroscience Center, University of Zurich, Zurich 8057, Switzerland
| | - Artëm E Masunov
- NanoScience Technology Center, Department of Chemistry, University of Central Florida, Orlando, FL 32826, USA; School of Modeling, Simulation and Training, University of Central Florida, Orlando, FL 32826, USA; National Research Nuclear University MEPhI, Kashirskoye Shosse 31, Moscow 115409, Russia; South Ural State University, Lenin Pr. 76, Chelyabinsk 454080, Russia
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Zürich 8057, Switzerland; Neuroscience Center, University of Zurich, Zurich 8057, Switzerland.
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA.
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39
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Zhang H, Gutruf P, Meacham K, Montana MC, Zhao X, Chiarelli AM, Vázquez-Guardado A, Norris A, Lu L, Guo Q, Xu C, Wu Y, Zhao H, Ning X, Bai W, Kandela I, Haney CR, Chanda D, Gereau RW, Rogers JA. Wireless, battery-free optoelectronic systems as subdermal implants for local tissue oximetry. SCIENCE ADVANCES 2019; 5:eaaw0873. [PMID: 30873435 PMCID: PMC6408152 DOI: 10.1126/sciadv.aaw0873] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 01/28/2019] [Indexed: 05/18/2023]
Abstract
Monitoring regional tissue oxygenation in animal models and potentially in human subjects can yield insights into the underlying mechanisms of local O2-mediated physiological processes and provide diagnostic and therapeutic guidance for relevant disease states. Existing technologies for tissue oxygenation assessments involve some combination of disadvantages in requirements for physical tethers, anesthetics, and special apparatus, often with confounding effects on the natural behaviors of test subjects. This work introduces an entirely wireless and fully implantable platform incorporating (i) microscale optoelectronics for continuous sensing of local hemoglobin dynamics and (ii) advanced designs in continuous, wireless power delivery and data output for tether-free operation. These features support in vivo, highly localized tissue oximetry at sites of interest, including deep brain regions of mice, on untethered, awake animal models. The results create many opportunities for studying various O2-mediated processes in naturally behaving subjects, with implications in biomedical research and clinical practice.
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Affiliation(s)
- Hao Zhang
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Philipp Gutruf
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208, USA
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ 85721, USA
| | - Kathleen Meacham
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Michael C. Montana
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Xingyue Zhao
- Department of Materials Science and Engineering and Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- State Key Laboratory of New Ceramics and Fine Processing and School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Antonio M. Chiarelli
- Institute of Advanced Biomedical Technologies and Department of Neuroscience, Imaging and Clinical Sciences, University G. D’Annunzio of Chieti–Pescara, Chieti 66100, Italy
| | - Abraham Vázquez-Guardado
- NanoScience Technology Center, Department of Physics and CREOL, The College of Optics and Photonics, University of Central Florida, Orlando, FL 32826, USA
| | - Aaron Norris
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Luyao Lu
- Department of Materials Science and Engineering and Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Qinglei Guo
- Department of Materials Science and Engineering and Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Materials Science, Fudan University, Shanghai 200433, China
| | - Chenkai Xu
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Yixin Wu
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Hangbo Zhao
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208, USA
| | - Xin Ning
- Department of Materials Science and Engineering and Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Wubin Bai
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208, USA
| | - Irawati Kandela
- Developmental Therapeutics Core, Northwestern University, Evanston, IL 60208, USA
- Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208, USA
| | - Chad R. Haney
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208, USA
- Center for Advanced Molecular Imaging, Northwestern University, Evanston, IL 60208, USA
| | - Debashis Chanda
- NanoScience Technology Center, Department of Physics and CREOL, The College of Optics and Photonics, University of Central Florida, Orlando, FL 32826, USA
| | - Robert W. Gereau
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Washington University Pain Center, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - John A. Rogers
- Departments of Materials Science and Engineering, Biomedical Engineering, Neurological Surgery, Chemistry, Mechanical Engineering, Electrical Engineering and Computer Science, Simpson Querrey Institute and Feinberg Medical School, Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208, USA
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40
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Keeley TP, Mann GE. Defining Physiological Normoxia for Improved Translation of Cell Physiology to Animal Models and Humans. Physiol Rev 2019; 99:161-234. [PMID: 30354965 DOI: 10.1152/physrev.00041.2017] [Citation(s) in RCA: 179] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The extensive oxygen gradient between the air we breathe (Po2 ~21 kPa) and its ultimate distribution within mitochondria (as low as ~0.5-1 kPa) is testament to the efforts expended in limiting its inherent toxicity. It has long been recognized that cell culture undertaken under room air conditions falls short of replicating this protection in vitro. Despite this, difficulty in accurately determining the appropriate O2 levels in which to culture cells, coupled with a lack of the technology to replicate and maintain a physiological O2 environment in vitro, has hindered addressing this issue thus far. In this review, we aim to address the current understanding of tissue Po2 distribution in vivo and summarize the attempts made to replicate these conditions in vitro. The state-of-the-art techniques employed to accurately determine O2 levels, as well as the issues associated with reproducing physiological O2 levels in vitro, are also critically reviewed. We aim to provide the framework for researchers to undertake cell culture under O2 levels relevant to specific tissues and organs. We envisage that this review will facilitate a paradigm shift, enabling translation of findings under physiological conditions in vitro to disease pathology and the design of novel therapeutics.
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Affiliation(s)
- Thomas P Keeley
- King's British Heart Foundation Centre of Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences and Medicine, King's College London , London , United Kingdom
| | - Giovanni E Mann
- King's British Heart Foundation Centre of Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences and Medicine, King's College London , London , United Kingdom
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Desjardins M, Kılıç K, Thunemann M, Mateo C, Holland D, Ferri CGL, Cremonesi JA, Li B, Cheng Q, Weldy KL, Saisan PA, Kleinfeld D, Komiyama T, Liu TT, Bussell R, Wong EC, Scadeng M, Dunn AK, Boas DA, Sakadžić S, Mandeville JB, Buxton RB, Dale AM, Devor A. Awake Mouse Imaging: From Two-Photon Microscopy to Blood Oxygen Level-Dependent Functional Magnetic Resonance Imaging. BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2018; 4:533-542. [PMID: 30691968 DOI: 10.1016/j.bpsc.2018.12.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 10/26/2018] [Accepted: 11/27/2018] [Indexed: 01/23/2023]
Abstract
BACKGROUND Functional magnetic resonance imaging (fMRI) in awake behaving mice is well positioned to bridge the detailed cellular-level view of brain activity, which has become available owing to recent advances in microscopic optical imaging and genetics, to the macroscopic scale of human noninvasive observables. However, though microscopic (e.g., two-photon imaging) studies in behaving mice have become a reality in many laboratories, awake mouse fMRI remains a challenge. Owing to variability in behavior among animals, performing all types of measurements within the same subject is highly desirable and can lead to higher scientific rigor. METHODS We demonstrated blood oxygenation level-dependent fMRI in awake mice implanted with long-term cranial windows that allowed optical access for microscopic imaging modalities and optogenetic stimulation. We started with two-photon imaging of single-vessel diameter changes (n = 1). Next, we implemented intrinsic optical imaging of blood oxygenation and flow combined with laser speckle imaging of blood flow obtaining a mesoscopic picture of the hemodynamic response (n = 16). Then we obtained corresponding blood oxygenation level-dependent fMRI data (n = 5). All measurements could be performed in the same mice in response to identical sensory and optogenetic stimuli. RESULTS The cranial window did not deteriorate the quality of fMRI and allowed alternation between imaging modalities in each subject. CONCLUSIONS This report provides a proof of feasibility for multiscale imaging approaches in awake mice. In the future, this protocol could be extended to include complex cognitive behaviors translatable to humans, such as sensory discrimination or attention.
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Affiliation(s)
- Michèle Desjardins
- Department of Radiology, University of California, San Diego, La Jolla, California.
| | - Kıvılcım Kılıç
- Department of Neurosciences, University of California, San Diego, La Jolla, California
| | - Martin Thunemann
- Department of Neurosciences, University of California, San Diego, La Jolla, California
| | - Celine Mateo
- Department of Physics, University of California, San Diego, La Jolla, California
| | - Dominic Holland
- Department of Neurosciences, University of California, San Diego, La Jolla, California
| | - Christopher G L Ferri
- Department of Neurosciences, University of California, San Diego, La Jolla, California
| | - Jonathan A Cremonesi
- Biology Undergraduate Program, University of California, San Diego, La Jolla, California
| | - Baoqiang Li
- Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown
| | - Qun Cheng
- Department of Neurosciences, University of California, San Diego, La Jolla, California
| | - Kimberly L Weldy
- Department of Neurosciences, University of California, San Diego, La Jolla, California
| | - Payam A Saisan
- Department of Neurosciences, University of California, San Diego, La Jolla, California
| | - David Kleinfeld
- Department of Physics, University of California, San Diego, La Jolla, California; Section of Neurobiology, University of California, San Diego, La Jolla, California; Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California
| | - Takaki Komiyama
- Department of Neurosciences, University of California, San Diego, La Jolla, California; Section of Neurobiology, University of California, San Diego, La Jolla, California
| | - Thomas T Liu
- Department of Radiology, University of California, San Diego, La Jolla, California
| | - Robert Bussell
- Department of Radiology, University of California, San Diego, La Jolla, California
| | - Eric C Wong
- Department of Radiology, University of California, San Diego, La Jolla, California
| | - Miriam Scadeng
- Department of Radiology, University of California, San Diego, La Jolla, California
| | - Andrew K Dunn
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas
| | - David A Boas
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts
| | - Sava Sakadžić
- Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown
| | - Joseph B Mandeville
- Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown
| | - Richard B Buxton
- Department of Radiology, University of California, San Diego, La Jolla, California
| | - Anders M Dale
- Department of Radiology, University of California, San Diego, La Jolla, California; Department of Neurosciences, University of California, San Diego, La Jolla, California
| | - Anna Devor
- Department of Radiology, University of California, San Diego, La Jolla, California; Department of Neurosciences, University of California, San Diego, La Jolla, California; Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown
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42
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Hosford PS, Gourine AV. What is the key mediator of the neurovascular coupling response? Neurosci Biobehav Rev 2018; 96:174-181. [PMID: 30481531 PMCID: PMC6331662 DOI: 10.1016/j.neubiorev.2018.11.011] [Citation(s) in RCA: 106] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 11/11/2018] [Accepted: 11/19/2018] [Indexed: 12/22/2022]
Abstract
Cellular and molecular mechanisms underlying increases in regional blood flow in response to neuronal activity are not fully understood. We have compared the effects of 79 in vivo and 36 in vitro experimental attempts to inhibit the neurovascular response. Blockade of neuronal NO synthase (nNOS) has the largest effect of any individual target, reducing the neurovascular response by 64%. This points to the existence of an unknown key signalling mechanism which accounts for approximately one third of the neurovascular response.
The mechanisms of neurovascular coupling contribute to ensuring brain energy supply is sufficient to meet demand. Despite significant research interest, the mechanisms underlying increases in regional blood flow that follow heightened neuronal activity are not completely understood. This article presents a systematic review and analysis of published data reporting the effects of pharmacological or genetic blockade of all hypothesised signalling pathways of neurovascular coupling. Our primary outcome measure was the percent reduction of the neurovascular response assessed using in vivo animal models. Selection criteria were met by 50 primary sources reporting the effects of 79 treatments. Experimental conditions were grouped into categories targeting mechanisms mediated by nitric oxide (NO), prostanoids, purines, potassium, amongst others. Blockade of neuronal NO synthase was found to have the largest effect of inhibiting any individual target, reducing the neurovascular response by 64% (average of 11 studies). Inhibition of multiple targets in combination with nNOS blockade had no further effect. This analysis points to the existence of an unknown signalling mechanism accounting for approximately one third of the neurovascular response.
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Affiliation(s)
- Patrick S Hosford
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & Pharmacology, University College London, London, UK; William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, London, UK.
| | - Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & Pharmacology, University College London, London, UK.
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Branco A, Francisco D, Hanscheid T. Is There a 'Normal' Oxygen Concentration for in vitro Plasmodium Cultures? Trends Parasitol 2018; 34:811-812. [PMID: 30049603 DOI: 10.1016/j.pt.2018.07.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 07/09/2018] [Indexed: 11/18/2022]
Affiliation(s)
- Ana Branco
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Denise Francisco
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Thomas Hanscheid
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal; Instituto de Microbiologia, Faculdade de Medicina, Universidade de Lisboa, Avenida Prof. Egas Moniz, 1649-028 Lisboa, Portugal.
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Akiyama H, Takahashi I, Shimoda Y, Mukai R, Yoshihara T, Tobita S. Ir(iii) complex-based oxygen imaging of living cells and ocular fundus with a gated ICCD camera. Photochem Photobiol Sci 2018; 17:846-853. [PMID: 29808210 DOI: 10.1039/c8pp00122g] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Phosphorescence lifetime imaging methods using oxygen-sensitive probes are very useful for visualizing the oxygen status of living cells and tissues with high spatial resolution. We aim to develop a useful oxygen detection technique combining a phosphorescent oxygen probe and an optimal detection method. Herein we present a biological oxygen imaging method using a microscope equipped with a gated intensified charge-coupled device (ICCD) camera as a detector and an Ir(iii) complex as a phosphorescent oxygen probe. Microscopic luminescence images of monolayer HT-29 cells (human colorectal adenocarcinoma cells) obtained using the cell-penetrating Ir(iii) complex BTPDM1 and an inverted microscope demonstrated that this method allowed visualization of the oxygen gradient produced in a monolayer of cultured cells when the monolayer is covered with a thin coverslip. Furthermore, combining the IR-emitting Ir(iii) complex DTTPH-PEG24 with a macrozoom microscope equipped with a gated ICCD camera enabled both the visualization of retinal vessels near the optic disc and the monitoring of oxygen level changes in a rabbit retina upon changing the inhaled oxygen content.
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Affiliation(s)
- H Akiyama
- Department of Ophthalmology and Medicine and Biological Science, Graduate School of Medicine, Gunma University, Showa-machi, Maebashi, Gunma 371-8512, Japan
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Barros LF, Bolaños JP, Bonvento G, Bouzier-Sore AK, Brown A, Hirrlinger J, Kasparov S, Kirchhoff F, Murphy AN, Pellerin L, Robinson MB, Weber B. Current technical approaches to brain energy metabolism. Glia 2018; 66:1138-1159. [PMID: 29110344 PMCID: PMC5903992 DOI: 10.1002/glia.23248] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 09/14/2017] [Accepted: 10/04/2017] [Indexed: 12/19/2022]
Abstract
Neuroscience is a technology-driven discipline and brain energy metabolism is no exception. Once satisfied with mapping metabolic pathways at organ level, we are now looking to learn what it is exactly that metabolic enzymes and transporters do and when, where do they reside, how are they regulated, and how do they relate to the specific functions of neurons, glial cells, and their subcellular domains and organelles, in different areas of the brain. Moreover, we aim to quantify the fluxes of metabolites within and between cells. Energy metabolism is not just a necessity for proper cell function and viability but plays specific roles in higher brain functions such as memory processing and behavior, whose mechanisms need to be understood at all hierarchical levels, from isolated proteins to whole subjects, in both health and disease. To this aim, the field takes advantage of diverse disciplines including anatomy, histology, physiology, biochemistry, bioenergetics, cellular biology, molecular biology, developmental biology, neurology, and mathematical modeling. This article presents a well-referenced synopsis of the technical side of brain energy metabolism research. Detail and jargon are avoided whenever possible and emphasis is given to comparative strengths, limitations, and weaknesses, information that is often not available in regular articles.
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Affiliation(s)
- L Felipe Barros
- Centro de Estudios Científicos (CECs), Valdivia, 5110466, Chile
| | - Juan P Bolaños
- Instituto de Biologia Funcional y Genomica-CSIC, Universidad de Salamanca, CIBERFES, Salamanca, 37007, Spain
| | - Gilles Bonvento
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Département de la Recherche Fondamentale (DRF), Institut de Biologie François Jacob, Molecular Imaging Research Center (MIRCen), CNRS UMR 9199, Université Paris-Sud, Université Paris-Saclay, Fontenay-aux-Roses, France
| | - Anne-Karine Bouzier-Sore
- Centre de Résonance Magnétique des Systèmes Biologiques UMR 5536, CNRS-Université Bordeaux 146 rue Léo-Saignat, Bordeaux, France
| | - Angus Brown
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Johannes Hirrlinger
- Carl Ludwig Institute of Physiology, University of Leipzig, Liebigstr. 27, D-04103, Leipzig, Germany
- Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Hermann-Rein-Str. 3, Göttingen, D-37075, Germany
| | - Sergey Kasparov
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, BS8 1TD, United Kingdom
- Baltic Federal University, Kalinigrad, Russian Federation
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, University of Saarland, Building 48, Homburg, 66421, Germany
| | - Anne N Murphy
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, 92093
| | - Luc Pellerin
- Département de Physiologie, 7 rue du Bugnon, Lausanne, CH1005, Switzerland
| | - Michael B Robinson
- Department of Pediatrics, and Department of Systems Pharmacology and Translational Therapeutics, Children's Hospital of Philadelphia Research Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, Zurich, Switzerland
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Hirakawa Y, Mizukami K, Yoshihara T, Takahashi I, Khulan P, Honda T, Mimura I, Tanaka T, Tobita S, Nangaku M. Intravital phosphorescence lifetime imaging of the renal cortex accurately measures renal hypoxia. Kidney Int 2018; 93:1483-1489. [DOI: 10.1016/j.kint.2018.01.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 12/13/2017] [Accepted: 01/11/2018] [Indexed: 12/31/2022]
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Lücker A, Secomb TW, Weber B, Jenny P. The Relation Between Capillary Transit Times and Hemoglobin Saturation Heterogeneity. Part 1: Theoretical Models. Front Physiol 2018; 9:420. [PMID: 29755365 PMCID: PMC5932636 DOI: 10.3389/fphys.2018.00420] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 04/04/2018] [Indexed: 12/23/2022] Open
Abstract
Capillary dysfunction impairs oxygen supply to parenchymal cells and often occurs in Alzheimer's disease, diabetes and aging. Disturbed capillary flow patterns have been shown to limit the efficacy of oxygen extraction and can be quantified using capillary transit time heterogeneity (CTH). However, the transit time of red blood cells (RBCs) through the microvasculature is not a direct measure of their capacity for oxygen delivery. Here we examine the relation between CTH and capillary outflow saturation heterogeneity (COSH), which is the heterogeneity of blood oxygen content at the venous end of capillaries. Models for the evolution of hemoglobin saturation heterogeneity (HSH) in capillary networks were developed and validated using a computational model with moving RBCs. Two representative situations were selected: a Krogh cylinder geometry with heterogeneous hemoglobin saturation (HS) at the inflow, and a parallel array of four capillaries. The heterogeneity of HS after converging capillary bifurcations was found to exponentially decrease with a time scale of 0.15-0.21 s due to diffusive interaction between RBCs. Similarly, the HS difference between parallel capillaries also drops exponentially with a time scale of 0.12-0.19 s. These decay times are substantially smaller than measured RBC transit times and only weakly depend on the distance between microvessels. This work shows that diffusive interaction strongly reduces COSH on a small spatial scale. Therefore, we conclude that CTH influences COSH yet does not determine it. The second part of this study will focus on simulations in microvascular networks from the rodent cerebral cortex. Actual estimates of COSH and CTH will then be given.
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Affiliation(s)
- Adrien Lücker
- Department of Mechanical and Process Engineering, Institute of Fluid Dynamics, ETH Zurich, Zurich, Switzerland
| | - Timothy W Secomb
- Department of Physiology, University of Arizona, Tucson, AZ, United States
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Patrick Jenny
- Department of Mechanical and Process Engineering, Institute of Fluid Dynamics, ETH Zurich, Zurich, Switzerland
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48
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Pries AR, Reglin B. Coronary microcirculatory pathophysiology: can we afford it to remain a black box? Eur Heart J 2018; 38:478-488. [PMID: 26843279 PMCID: PMC5381591 DOI: 10.1093/eurheartj/ehv760] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 12/27/2015] [Indexed: 01/04/2023] Open
Abstract
Coronary microvascular networks play the key role in determining blood flow distribution in the heart. Matching local blood supply to tissue metabolic demand entails continuous adaptation of coronary vessels via regulation of smooth muscle tone and structural dilated vessel diameter. The importance of coronary microcirculation for relevant pathological conditions including angina in patients with normal or near-normal coronary angiograms [microvascular angina (MVA)] and heart failure with preserved ejection fraction (HFpEF) is increasingly recognized. For MVA, clinical studies have shown a prevalence of up to 40% in patients with suspected coronary artery disease and a relevant impact on adverse cardiovascular events including cardiac death, stroke, and heart failure. Despite a continuously increasing number of corresponding clinical studies, the knowledge on pathophysiological cause–effect relations involving coronary microcirculation is, however, still very limited. A number of pathophysiological hypotheses for MVA and HFpEF have been suggested but are not established to a degree, which would allow definition of nosological entities, stratification of affected patients, or development of effective therapeutic strategies. This may be related to a steep decline in experimental (animal) pathophysiological studies in this area during the last 15 years. Since technology to experimentally investigate microvascular pathophysiology in the beating heart is increasingly, in principle, available, a concerted effort to build ‘coronary microcirculatory observatories’ to close this gap and to accelerate clinical progress in this area is suggested.
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Affiliation(s)
- Axel R Pries
- Department of Physiology, Center for Cardiovascular Research, Charité, Charitéplatz 1, D-10117 Berlin, Germany.,Deutsches Herzzentrum Berlin, Augustenburger Platz 1, D-13353 Berlin, Germany
| | - Bettina Reglin
- Department of Physiology, Center for Cardiovascular Research, Charité, Charitéplatz 1, D-10117 Berlin, Germany
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Daniels RE, McKenzie LK, Shewring JR, Weinstein JA, Kozhevnikov VN, Bryant HE. Pyridazine-bridged cationic diiridium complexes as potential dual-mode bioimaging probes. RSC Adv 2018; 8:9670-9676. [PMID: 31497293 PMCID: PMC6688561 DOI: 10.1039/c8ra00265g] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 03/01/2018] [Indexed: 12/14/2022] Open
Abstract
A novel diiridium complex [(N^C^N)2Ir(bis-N^C)Ir(N^C^N)2Cl]PF6 (N^C^N = 2-[3-tert-butyl-5-(pyridin-2-yl)phenyl]pyridine; bis-N^C = 3,6-bis(4-tert-butylphenyl)pyridazine) was designed, synthesised and characterised. The key feature of the complex is the bridging pyridazine ligand which brings two cyclometallated Ir(iii) metal centres close together so that Cl also acts as a bridging ligand leading to a cationic complex. The ionic nature of the complex offers a possibility of improving solubility in water. The complex displays broad emission in the red region (λem = 520–720 nm, τ = 1.89 μs, Φem = 62% in degassed acetonitrile). Cellular assays by multiphoton (λex = 800 nm) and confocal (λex = 405 nm) microscopy demonstrate that the complex enters cells and localises to the mitochondria, demonstrating cell permeability. Further, an appreciable yield of singlet oxygen generation (ΦΔ = 0.45, direct method, by 1O2 NIR emission in air equilibrated acetonitrile) suggests a possible future use in photodynamic therapy. However, the complex has relatively high dark toxicity (LD50 = 4.46 μM), which will likely hinder its clinical application. Despite this toxicity, the broad emission spectrum of the complex and high emission yield observed suggest a possible future use of this class of compound in emission bioimaging. The presence of two heavy atoms also increases the scattering of electrons, supporting potential future applications as a dual fluorescence and electron microscopy probe. A novel cell permeable, mitochondria localising, diiridium complex has a high emission yield and two heavy atoms to increase scattering of electrons, supporting potential future applications as a dual fluorescence and electron microscopy probe.![]()
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Affiliation(s)
- Ruth E Daniels
- Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Tyne and Wear NE1 8ST, Newcastle Upon Tyne, UK. ; Tel: +44 (0) 191 243 7430
| | - Luke K McKenzie
- Department of Chemistry, University of Sheffield, Dainton Building, Sheffield S3 7HF, UK.,Academic Unit of Molecular Oncology, Sheffield Institute for Nucleic Acids (SInFoNiA), Department of Oncology and Metabolism, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK. ; ; Tel: +44 (0) 114 2759040
| | - Jonathan R Shewring
- Department of Chemistry, University of Sheffield, Dainton Building, Sheffield S3 7HF, UK
| | - Julia A Weinstein
- Department of Chemistry, University of Sheffield, Dainton Building, Sheffield S3 7HF, UK
| | - Valery N Kozhevnikov
- Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Tyne and Wear NE1 8ST, Newcastle Upon Tyne, UK. ; Tel: +44 (0) 191 243 7430
| | - Helen E Bryant
- Academic Unit of Molecular Oncology, Sheffield Institute for Nucleic Acids (SInFoNiA), Department of Oncology and Metabolism, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK. ; ; Tel: +44 (0) 114 2759040
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50
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Lücker A, Secomb TW, Weber B, Jenny P. The relative influence of hematocrit and red blood cell velocity on oxygen transport from capillaries to tissue. Microcirculation 2018; 24. [PMID: 27893186 DOI: 10.1111/micc.12337] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 11/24/2016] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Oxygen transport to parenchymal cells occurs mainly at the microvascular level and depends on convective RBC flux, which is proportional in an individual capillary to the product of capillary hematocrit and RBC velocity. This study investigates the relative influence of these two factors on tissue PO2 . METHODS A simple analytical model is used to quantify the respective influences of hematocrit, RBC velocity, and RBC flow on tissue oxygenation around capillaries. Predicted tissue PO2 levels are compared with a detailed computational model. RESULTS Hematocrit is shown to have a larger influence on tissue PO2 than RBC velocity. The effect of RBC velocity increases with distance from the arterioles. Good agreement between analytical and numerical results is obtained, and the discrepancies are explained. Significant dependence of MTCs on RBC velocity at low hematocrit is demonstrated. CONCLUSIONS For a given RBC flux in a capillary, the PO2 in the surrounding tissue increases with increasing hematocrit, as a consequence of decreasing IVR to diffusive oxygen transport from RBCs to tissue. These results contribute to understanding the effects of blood flow changes on oxygen transport, such as those that occur in functional hyperemia in the brain.
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Affiliation(s)
- Adrien Lücker
- Institute of Fluid Dynamics, ETH Zurich, Zurich, Switzerland
| | - Timothy W Secomb
- Department of Physiology, University of Arizona, Tucson, AZ, USA
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Patrick Jenny
- Institute of Fluid Dynamics, ETH Zurich, Zurich, Switzerland
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