1
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Shen Z, Lu Y, Ren Y, Wang Z, Deng J, Nan D, Jia J, Yu W, Jin Y, Sun W, Huang Y, Qu X, Jin H. The relationship between ischemic penumbra progression and the oxygen content of cortex microcirculation in acute ischemic stroke. Neurotherapeutics 2024:e00387. [PMID: 38918128 DOI: 10.1016/j.neurot.2024.e00387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 05/21/2024] [Accepted: 06/12/2024] [Indexed: 06/27/2024] Open
Abstract
The precise oxygen content thresholds of ischemic deep parenchymal (OCIDP) and that in cortical microcirculation (OCCM), which leads to ischemic penumbra converting into the infarcted core, remain uncertain. This study employed an invasive fiber-optic oxygen meter and a newly developed oxygen-responsive probe called RuA3-Cy5-rtPA (RC-rtPA) based on recombinant tissue-type plasminogen activator (rtPA) to examine the oxygen content thresholds. A mouse model of middle cerebral artery occlusion was generated and animals were randomly divided into a sham, 24-h reperfusion after 3-h ischemia (IR 3-h), and IR 6-h groups, all of which were sacrificed following reperfusion. Stroke severity was evaluated based on the infarction area, neurological symptoms, microcirculation perfusion, and microemboli in microcirculation. OCIDP was characterized based on its extent and distribution, whereas OCCM was measured using RC-rtPA. During ischemia, stroke severity escalation manifested as increasing infarction area, severe neurologic symptoms, and poorer microcirculation perfusion with more microthrombi depositions. OCIDP presented rapid decline following artery occlusion along with a gradual increase in the hypoxic area. Within 3 h following ischemia induction, the ischemic tissue that experienced hypoxia could be rescued, and this reversibility would disappear after 6 h. Within 6 h, OCCM continued to decrease. A significant decrease in oxygen content in cortical venules and cortical parenchyma was observed. These findings assist in establishing the extent of the ischemic penumbra at the microcirculation level and offer a foundation for assessing the ischemic penumbra that could respond positively to reperfusion therapy beyond the typical time window.
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Affiliation(s)
- Zhiyuan Shen
- Department of Neurology, Peking University First Hospital, Beijing 100034, China; Department of Neurology, First Hospital of Hebei Medical University, Shijiazhuang 050030, China
| | - Yuxuan Lu
- Department of Neurology, Peking University First Hospital, Beijing 100034, China
| | - Yingying Ren
- Center of Materials Science and Optoelectronics Engineering, College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhaoxia Wang
- Department of Neurology, Peking University First Hospital, Beijing 100034, China
| | - Jianwen Deng
- Department of Neurology, Peking University First Hospital, Beijing 100034, China
| | - Ding Nan
- Department of Neurology, Peking University First Hospital, Beijing 100034, China
| | - Jingjing Jia
- Department of Neurology, Peking University First Hospital, Beijing 100034, China
| | - Weiwei Yu
- Department of Neurology, Peking University First Hospital, Beijing 100034, China
| | - Yunyi Jin
- Department of Neurology, Peking University First Hospital, Beijing 100034, China
| | - Wei Sun
- Department of Neurology, Peking University First Hospital, Beijing 100034, China
| | - Yining Huang
- Department of Neurology, Peking University First Hospital, Beijing 100034, China
| | - Xiaozhong Qu
- Center of Materials Science and Optoelectronics Engineering, College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Haiqiang Jin
- Department of Neurology, Peking University First Hospital, Beijing 100034, China.
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2
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Pian Q, Alfadhel M, Tang J, Lee GV, Li B, Fu B, Ayata Y, Yaseen MA, Boas DA, Secomb TW, Sakadzic S. Cortical microvascular blood flow velocity mapping by combining dynamic light scattering optical coherence tomography and two-photon microscopy. JOURNAL OF BIOMEDICAL OPTICS 2023; 28:076003. [PMID: 37484973 PMCID: PMC10362155 DOI: 10.1117/1.jbo.28.7.076003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 05/30/2023] [Accepted: 06/05/2023] [Indexed: 07/25/2023]
Abstract
Significance The accurate large-scale mapping of cerebral microvascular blood flow velocity is crucial for a better understanding of cerebral blood flow (CBF) regulation. Although optical imaging techniques enable both high-resolution microvascular angiography and fast absolute CBF velocity measurements in the mouse cortex, they usually require different imaging techniques with independent system configurations to maximize their performances. Consequently, it is still a challenge to accurately combine functional and morphological measurements to co-register CBF speed distribution from hundreds of microvessels with high-resolution microvascular angiograms. Aim We propose a data acquisition and processing framework to co-register a large set of microvascular blood flow velocity measurements from dynamic light scattering optical coherence tomography (DLS-OCT) with the corresponding microvascular angiogram obtained using two-photon microscopy (2PM). Approach We used DLS-OCT to first rapidly acquire a large set of microvascular velocities through a sealed cranial window in mice and then to acquire high-resolution microvascular angiograms using 2PM. The acquired data were processed in three steps: (i) 2PM angiogram coregistration with the DLS-OCT angiogram, (ii) 2PM angiogram segmentation and graphing, and (iii) mapping of the CBF velocities to the graph representation of the 2PM angiogram. Results We implemented the developed framework on the three datasets acquired from the mice cortices to facilitate the coregistration of the large sets of DLS-OCT flow velocity measurements with 2PM angiograms. We retrieved the distributions of red blood cell velocities in arterioles, venules, and capillaries as a function of the branching order from precapillary arterioles and postcapillary venules from more than 1000 microvascular segments. Conclusions The proposed framework may serve as a useful tool for quantitative analysis of large microvascular datasets obtained by OCT and 2PM in studies involving normal brain functioning, progression of various diseases, and numerical modeling of the oxygen advection and diffusion in the realistic microvascular networks.
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Affiliation(s)
- Qi Pian
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
| | - Mohammed Alfadhel
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
- Northeastern University, Department of Bioengineering, Boston, Massachusetts, United States
| | - Jianbo Tang
- Southern University of Science and Technology, Department of Biomedical Engineering, Shenzhen, China
| | - Grace V. Lee
- University of Arizona, Program in Applied Mathematics, Tucson, Arizona, United States
| | - Baoqiang Li
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
- Chinese Academy of Sciences, Shenzhen Institute of Advanced Technology, Brain Cognition and Brain Disease Institute; Shenzhen Fundamental Research Institutions, Shenzhen–Hong Kong Institute of Brain Science, Shenzhen, Guangdong, China
| | - Buyin Fu
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
| | - Yagmur Ayata
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
| | - Mohammad Abbas Yaseen
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
- Northeastern University, Department of Bioengineering, Boston, Massachusetts, United States
| | - David A. Boas
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Timothy W. Secomb
- University of Arizona, Program in Applied Mathematics, Tucson, Arizona, United States
- University of Arizona, Department of Mathematics, Tucson, Arizona, United States
- University of Arizona, Department of Physiology, Tucson, Arizona, United States
| | - Sava Sakadzic
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
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3
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Roy TK, Secomb TW. Functional implications of microvascular heterogeneity for oxygen uptake and utilization. Physiol Rep 2022; 10:e15303. [PMID: 35581743 PMCID: PMC9114652 DOI: 10.14814/phy2.15303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 04/27/2022] [Accepted: 04/29/2022] [Indexed: 06/15/2023] Open
Abstract
In the vascular system, an extensive network structure provides convective and diffusive transport of oxygen to tissue. In the microcirculation, parameters describing network structure, blood flow, and oxygen transport are highly heterogeneous. This heterogeneity can strongly affect oxygen supply and organ function, including reduced oxygen uptake in the lung and decreased oxygen delivery to tissue. The causes of heterogeneity can be classified as extrinsic or intrinsic. Extrinsic heterogeneity refers to variations in oxygen demand in the systemic circulation or oxygen supply in the lungs. Intrinsic heterogeneity refers to structural heterogeneity due to stochastic growth of blood vessels and variability in flow pathways due to geometric constraints, and resulting variations in blood flow and hematocrit. Mechanisms have evolved to compensate for heterogeneity and thereby improve oxygen uptake in the lung and delivery to tissue. These mechanisms, which involve long-term structural adaptation and short-term flow regulation, depend on upstream responses conducted along vessel walls, and work to redistribute flow and maintain blood and tissue oxygenation. Mathematically, the variance of a functional quantity such as oxygen delivery that depends on two or more heterogeneous variables can be reduced if one of the underlying variables is controlled by an appropriate compensatory mechanism. Ineffective regulatory mechanisms can result in poor oxygen delivery even in the presence of adequate overall tissue perfusion. Restoration of endothelial function, and specifically conducted responses, should be considered when addressing tissue hypoxemia and organ failure in clinical settings.
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Affiliation(s)
- Tuhin K. Roy
- Department of AnesthesiologyMayo ClinicRochesterMinnesotaUSA
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4
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Control of low flow regions in the cortical vasculature determines optimal arterio-venous ratios. Proc Natl Acad Sci U S A 2021; 118:2021840118. [PMID: 34413186 DOI: 10.1073/pnas.2021840118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The energy demands of neurons are met by a constant supply of glucose and oxygen via the cerebral vasculature. The cerebral cortex is perfused by dense, parallel arterioles and venules, consistently in imbalanced ratios. Whether and how arteriole-venule arrangement and ratio affect the efficiency of energy delivery to the cortex has remained an unanswered question. Here, we show by mathematical modeling and analysis of the mapped mouse sensory cortex that the perfusive efficiency of the network is predicted to be limited by low-flow regions produced between pairs of arterioles or pairs of venules. Increasing either arteriole or venule density decreases the size of these low-flow regions, but increases their number, setting an optimal ratio between arterioles and venules that matches closely that observed across mammalian cortical vasculature. Low-flow regions are reshaped in complex ways by changes in vascular conductance, creating geometric challenges for matching cortical perfusion with neuronal activity.
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5
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Modular microenvironment components reproduce vascular dynamics de novo in a multi-scale agent-based model. Cell Syst 2021; 12:795-809.e9. [PMID: 34139155 DOI: 10.1016/j.cels.2021.05.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 11/06/2020] [Accepted: 05/11/2021] [Indexed: 12/24/2022]
Abstract
Cells do not exist in isolation; they continuously act within and react to their environment. And this environment is not static; it continuously adapts and responds to cells. Here, we investigate how vascular structure and function impact emergent cell population behavior using an agent-based model (ABM). Our ABM enables researchers to "mix and match" cell agents, subcellular modules, and microenvironment components ranging from simple nutrient sources to complex, realistic vascular architectures that accurately capture hemodynamics. We use this ABM to highlight the bilateral relationship between cells and nearby vasculature, demonstrate the effect of vascular structure on environmental heterogeneity, and emphasize the non-linear, non-intuitive relationship between vascular function and the behavior of cell populations over time. Our ABM is well suited to characterizing in vitro and in vivo studies, with applications from basic science to translational synthetic biology and medicine. The model is freely available at https://github.com/bagherilab/ARCADE. A record of this paper's transparent peer review process is included in the supplemental information.
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6
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Belcher DA, Lucas A, Cabrales P, Palmer AF. Tumor vascular status controls oxygen delivery facilitated by infused polymerized hemoglobins with varying oxygen affinity. PLoS Comput Biol 2020; 16:e1008157. [PMID: 32817659 PMCID: PMC7462268 DOI: 10.1371/journal.pcbi.1008157] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 09/01/2020] [Accepted: 07/16/2020] [Indexed: 11/19/2022] Open
Abstract
Oxygen (O2) delivery facilitated by hemoglobin (Hb)-based O2 carriers (HBOCs) is a promising strategy to increase the effectiveness of chemotherapeutics for treatment of solid tumors. However, the heterogeneous vascular structures present within tumors complicates evaluating the oxygenation potential of HBOCs within the tumor microenvironment. To account for spatial variations in the vasculature and tumor tissue that occur during tumor growth, we used a computational model to develop artificial tumor constructs. With these simulated tumors, we performed a polymerized human hemoglobin (hHb) (PolyhHb) enhanced oxygenation simulation accounting for differences in the physiologic characteristics of human and mouse blood. The results from this model were used to determine the potential effectiveness of different treatment options including a top load (low volume) and exchange (large volume) infusion of a tense quaternary state (T-State) PolyhHb, relaxed quaternary state (R-State) PolyhHb, and a non O2 carrying control. Principal component analysis (PCA) revealed correlations between the different regimes of effectiveness within the different simulated dosage options. In general, we found that infusion of T-State PolyhHb is more likely to decrease tissue hypoxia and modulate the metabolic rate of O2 consumption. Though the developed models are not a definitive descriptor of O2 carrier interaction in tumor capillary networks, we accounted for factors such as non-uniform vascular density and permeability that limit the applicability of O2 carriers during infusion. Finally, we have used these validated computational models to establish potential benchmarks to guide tumor treatment during translation of PolyhHb mediated therapies into clinical applications. High rates of oxygen consumption and abnormal vascularization lead to low oxygen levels within solid tumors. The lack of oxygen results in resistance to chemotherapies and increased rates of cancer progression. Hemoglobin-based oxygen carriers have the potential to increase the amount of oxygen delivered to tumors, which may make chemotherapies more effective. Unfortunately, translating experimental results from mice to humans is complicated by allometric scaling between mice and humans. To predict how these therapies may perform differently between human and murine systems, we computationally predicted how hemoglobin-based oxygen delivery varies between the two organisms. Our model accounts for how variations in the tumor vascular network impact the performance of hemoglobin-based oxygen carriers. This model also allows us to assess how the oxygen affinity of hemoglobin-based oxygen carriers affects the oxygenation of hypoxic tissue. The results of these models help us predict how results from murine models may translate to humans. Also, our models help to highlight what clinically-measurable tumor properties should be measured to predict the effectiveness of hemoglobin-based oxygen carriers in biological systems.
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Affiliation(s)
- Donald A. Belcher
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio, United States of America
| | - Alfredo Lucas
- Department of Bioengineering, University of California, San Diego, La Jolla, California, United States of America
| | - Pedro Cabrales
- Department of Bioengineering, University of California, San Diego, La Jolla, California, United States of America
| | - Andre F. Palmer
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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7
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Yoon C, Qi Y, Mestre H, Canavesi C, Marola OJ, Cogliati A, Nedergaard M, Libby RT, Rolland JP. Gabor domain optical coherence microscopy combined with laser scanning confocal fluorescence microscopy. BIOMEDICAL OPTICS EXPRESS 2019; 10:6242-6257. [PMID: 31853397 PMCID: PMC6913392 DOI: 10.1364/boe.10.006242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 10/26/2019] [Accepted: 11/05/2019] [Indexed: 06/10/2023]
Abstract
We report on the development of fluorescence Gabor domain optical coherence microscopy (Fluo GD-OCM), a combination of GD-OCM with laser scanning confocal fluorescence microscopy (LSCFM) for synchronous micro-structural and fluorescence imaging. The dynamic focusing capability of GD-OCM provided the adaptive illumination environment for both modalities without any mechanical movement. Using Fluo GD-OCM, we imaged ex vivo DsRed-expressing cells in the brain of a transgenic mouse, as well as Cy3-labeled ganglion cells and Cy3-labeled astrocytes from a mouse retina. The self-registration of images taken by the two different imaging modalities showed the potential for a correlative study of subjects and double identification of the target.
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Affiliation(s)
- Changsik Yoon
- The Institute of Optics, University of Rochester, Wilmot Building, Rochester, New York 14627, USA
| | - Yue Qi
- Department of Biomedical Engineering, University of Rochester, Robert B. Goergen Hall, Rochester, New York 14627, USA
| | - Humberto Mestre
- Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, New York 14642, USA
| | - Cristina Canavesi
- LighTopTech Corp., 150 Lucius Gordon Dr., Ste 201, West Henrietta, New York 14586, USA
| | - Olivia J. Marola
- Flaum Eye Institute, Department of Ophthalmology, University of Rochester Medical Center, Rochester, New York 14642, USA
| | - Andrea Cogliati
- LighTopTech Corp., 150 Lucius Gordon Dr., Ste 201, West Henrietta, New York 14586, USA
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, New York 14642, USA
| | - Richard T. Libby
- Flaum Eye Institute, Department of Ophthalmology, University of Rochester Medical Center, Rochester, New York 14642, USA
| | - Jannick P. Rolland
- The Institute of Optics, University of Rochester, Wilmot Building, Rochester, New York 14627, USA
- Department of Biomedical Engineering, University of Rochester, Robert B. Goergen Hall, Rochester, New York 14627, USA
- LighTopTech Corp., 150 Lucius Gordon Dr., Ste 201, West Henrietta, New York 14586, USA
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8
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Handwerker J, Pérez-Rodas M, Beyerlein M, Vincent F, Beck A, Freytag N, Yu X, Pohmann R, Anders J, Scheffler K. A CMOS NMR needle for probing brain physiology with high spatial and temporal resolution. Nat Methods 2019; 17:64-67. [PMID: 31768059 DOI: 10.1038/s41592-019-0640-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 10/07/2019] [Indexed: 02/06/2023]
Abstract
Magnetic resonance imaging and spectroscopy are versatile methods for probing brain physiology, but their intrinsically low sensitivity limits the achievable spatial and temporal resolution. Here, we introduce a monolithically integrated NMR-on-a-chip needle that combines an ultra-sensitive 300 µm NMR coil with a complete NMR transceiver, enabling in vivo measurements of blood oxygenation and flow in nanoliter volumes at a sampling rate of 200 Hz.
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Affiliation(s)
- Jonas Handwerker
- Institute of Smart Sensors, University of Stuttgart, Stuttgart, Germany. .,Institute of Microelectronics, University of Ulm, Ulm, Germany.
| | - Marlon Pérez-Rodas
- Department for High-field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.,Graduate Training Centre of Neuroscience, IMPRS for Cognitive and Systems Neuroscience, University of Tübingen, Tübingen, Germany
| | - Michael Beyerlein
- Department for Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | | | - Armin Beck
- Bruker BioSpin AG, Fällanden, Switzerland
| | | | - Xin Yu
- Department for High-field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Rolf Pohmann
- Department for High-field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Jens Anders
- Institute of Smart Sensors, University of Stuttgart, Stuttgart, Germany. .,Institute of Microelectronics, University of Ulm, Ulm, Germany. .,Center for Integrated Quantum Science and Technology, Stuttgart, Germany.
| | - Klaus Scheffler
- Department for High-field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Germany. .,Department for Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany.
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9
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Erdener ŞE, Dalkara T. Small Vessels Are a Big Problem in Neurodegeneration and Neuroprotection. Front Neurol 2019; 10:889. [PMID: 31474933 PMCID: PMC6707104 DOI: 10.3389/fneur.2019.00889] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Accepted: 08/01/2019] [Indexed: 12/11/2022] Open
Abstract
The cerebral microcirculation holds a critical position to match the high metabolic demand by neuronal activity. Functionally, microcirculation is virtually inseparable from other nervous system cells under both physiological and pathological conditions. For successful bench-to-bedside translation of neuroprotection research, the role of microcirculation in acute and chronic neurodegenerative disorders appears to be under-recognized, which may have contributed to clinical trial failures with some neuroprotectants. Increasing data over the last decade suggest that microcirculatory impairments such as endothelial or pericyte dysfunction, morphological irregularities in capillaries or frequent dynamic stalls in blood cell flux resulting in excessive heterogeneity in capillary transit may significantly compromise tissue oxygen availability. We now know that ischemia-induced persistent abnormalities in capillary flow negatively impact restoration of reperfusion after recanalization of occluded cerebral arteries. Similarly, microcirculatory impairments can accompany or even precede neural loss in animal models of several neurodegenerative disorders including Alzheimer's disease. Macrovessels are relatively easy to evaluate with radiological or experimental imaging methods but they cannot faithfully reflect the downstream microcirculatory disturbances, which may be quite heterogeneous across the tissue at microscopic scale and/or happen fast and transiently. The complexity and size of the elements of microcirculation, therefore, require utilization of cutting-edge imaging techniques with high spatiotemporal resolution as well as multidisciplinary team effort to disclose microvascular-neurodegenerative connection and to test treatment approaches to advance the field. Developments in two photon microscopy, ultrafast ultrasound, and optical coherence tomography provide valuable experimental tools to reveal those microscopic events with high resolution. Here, we review the up-to-date advances in understanding of the primary microcirculatory abnormalities that can result in neurodegenerative processes and the combined neurovascular protection approaches that can prevent acute as well as chronic neurodegeneration.
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Affiliation(s)
- Şefik Evren Erdener
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
| | - Turgay Dalkara
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey.,Department of Neurology, Faculty of Medicine, Hacettepe University, Ankara, Turkey
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10
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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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11
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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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12
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Rutkai I, Merdzo I, Wunnava SV, Curtin GT, Katakam PVG, Busija DW. Cerebrovascular function and mitochondrial bioenergetics after ischemia-reperfusion in male rats. J Cereb Blood Flow Metab 2019; 39:1056-1068. [PMID: 29215305 PMCID: PMC6547195 DOI: 10.1177/0271678x17745028] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 11/06/2017] [Indexed: 12/16/2022]
Abstract
The underlying factors promoting increased mitochondrial proteins, mtDNA, and dilation to mitochondrial-specific agents in male rats following tMCAO are not fully elucidated. Our goal was to determine the morphological and functional effects of ischemia/reperfusion (I/R) on mitochondria using electron microscopy, Western blot, mitochondrial oxygen consumption rate (OCR), and Ca2+ sparks activity measurements in middle cerebral arteries (MCAs) from male Sprague Dawley rats (Naïve, tMCAO, Sham). We found a greatly increased OCR in ipsilateral MCAs (IPSI) compared with contralateral (CONTRA), Sham, and Naïve MCAs. Consistent with our earlier findings, the expression of Mitofusin-2 and OPA-1 was significantly decreased in IPSI arteries compared with Sham and Naïve. Mitochondrial morphology was disrupted in vascular smooth muscle, but morphology with normal and perhaps greater numbers of mitochondria were observed in IPSI compared with CONTRA MCAs. Consistently, there were significantly fewer baseline Ca2+ events in IPSI MCAs compared with CONTRA, Sham, and Naïve. Mitochondrial depolarization significantly increased Ca2+ sparks activity in the IPSI, Sham, Naïve, but not in the CONTRA group. Our data indicate that altered mitochondrial structure and function occur in MCAs exposed to I/R and that these changes impact not only OCR but Ca2+ sparks activity in both IPSI and CONTRA MCAs.
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Affiliation(s)
- Ibolya Rutkai
- Department of Pharmacology,
Tulane
University School of Medicine, New Orleans,
LA, USA
| | - Ivan Merdzo
- Department of Pharmacology,
Tulane
University School of Medicine, New Orleans,
LA, USA
- Department of Pharmacology, University
of Mostar School of Medicine, Mostar, Bosnia and Herzegovina
| | - Sanjay V Wunnava
- Department of Pharmacology,
Tulane
University School of Medicine, New Orleans,
LA, USA
| | - Genevieve T Curtin
- Department of Pharmacology,
Tulane
University School of Medicine, New Orleans,
LA, USA
| | - Prasad VG Katakam
- Department of Pharmacology,
Tulane
University School of Medicine, New Orleans,
LA, USA
| | - David W Busija
- Department of Pharmacology,
Tulane
University School of Medicine, New Orleans,
LA, USA
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13
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Cao R, Li J, Zhang C, Zuo Z, Hu S. Photoacoustic microscopy of obesity-induced cerebrovascular alterations. Neuroimage 2018; 188:369-379. [PMID: 30553918 DOI: 10.1016/j.neuroimage.2018.12.027] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 12/05/2018] [Accepted: 12/12/2018] [Indexed: 12/14/2022] Open
Abstract
Cerebral small vessel disease has been linked to cognitive, psychiatric and physical disabilities, especially in the elderly. However, the underlying pathophysiology remains incompletely understood, largely due to the limited accessibility of these small vessels in the live brain. Here, we report an intravital imaging and analysis platform for high-resolution, quantitative and comprehensive characterization of pathological alterations in the mouse cerebral microvasculature. By exploiting multi-parametric photoacoustic microscopy (PAM), microvascular structure, blood perfusion, oxygenation and flow were imaged in the awake brain. With the aid of vessel segmentation, these structural and functional parameters were extracted at the single-microvessel level, from which vascular density, tortuosity, wall shear stress, resistance and associated cerebral oxygen extraction fraction and metabolism were also quantified. With the use of vasodilatory stimulus, multifaceted cerebrovascular reactivity (CVR) was characterized in vivo. By extending the classic Evans blue assay to in vivo, permeability of the blood-brain barrier (BBB) was dynamically evaluated. The utility of this enabling technique was examined by studying cerebrovascular alterations in an established mouse model of high-fat diet-induced obesity. Our results revealed increased vascular density, reduced arterial flow, enhanced oxygen extraction, impaired BBB integrity, and increased multifaceted CVR in the obese brain. Interestingly, the 'counterintuitive' increase of CVR was supported by the elevated active endothelial nitric oxide synthase in the obese mouse. Providing comprehensive and quantitative insights into cerebral microvessels and their responses under pathological conditions, this technique opens a new door to mechanistic studies of the cerebral small vessel disease and its implications in neurodegeneration and stroke.
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Affiliation(s)
- Rui Cao
- Department of Biomedical Engineering, University of Virginia, Charlottesville, USA
| | - Jun Li
- Department of Anesthesiology, University of Virginia, Charlottesville, USA
| | - Chenchu Zhang
- Department of Biomedical Engineering, University of Virginia, Charlottesville, USA
| | - Zhiyi Zuo
- Department of Anesthesiology, University of Virginia, Charlottesville, USA.
| | - Song Hu
- Department of Biomedical Engineering, University of Virginia, Charlottesville, USA.
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14
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Şencan İ, Esipova TV, Yaseen MA, Fu B, Boas DA, Vinogradov SA, Shahidi M, Sakadžić S. Two-photon phosphorescence lifetime microscopy of retinal capillary plexus oxygenation in mice. JOURNAL OF BIOMEDICAL OPTICS 2018; 23:1-9. [PMID: 30516039 PMCID: PMC6278707 DOI: 10.1117/1.jbo.23.12.126501] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 11/07/2018] [Indexed: 05/23/2023]
Abstract
Impaired oxygen delivery and/or consumption in the retinal tissue underlies the pathophysiology of many retinal diseases. However, the essential tools for measuring oxygen concentration in retinal capillaries and studying oxygen transport to retinal tissue are still lacking. We show that two-photon phosphorescence lifetime microscopy can be used to map absolute partial pressures of oxygen (pO2) in the retinal capillary plexus. Measurements were performed at various retinal depths in anesthetized mice under systemic normoxic and hyperoxic conditions. We used a newly developed two-photon phosphorescent oxygen probe, based on a two-photon absorbing platinum tetraphthalimidoporphyrin, and commercially available optics without correction for optical aberrations of the eye. The transverse and axial distances within the tissue volume were calibrated using a model of the eye's optical system. We believe this is the first demonstration of in vivo depth-resolved imaging of pO2 in retinal capillaries. Application of this method has the potential to advance our understanding of oxygen delivery on the microvascular scale and help elucidate mechanisms underlying various retinal diseases.
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Affiliation(s)
- İkbal Şencan
- Massachusetts General Hospital, Harvard Medical School, Athinuola A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
| | - Tatiana V. Esipova
- University of Pennsylvania, Departments of Biochemistry and Biophysics and of Chemistry, Philadelphia, Pennsylvania, United States
| | - Mohammad A. Yaseen
- Massachusetts General Hospital, Harvard Medical School, Athinuola A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
| | - Buyin Fu
- Massachusetts General Hospital, Harvard Medical School, Athinuola A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
| | - David A. Boas
- Massachusetts General Hospital, Harvard Medical School, Athinuola A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Sergei A. Vinogradov
- University of Pennsylvania, Departments of Biochemistry and Biophysics and of Chemistry, Philadelphia, Pennsylvania, United States
| | - Mahnaz Shahidi
- University of Southern California, Departments of Ophthalmology and Biomedical Engineering, Los Angeles, California, United States
| | - Sava Sakadžić
- Massachusetts General Hospital, Harvard Medical School, Athinuola A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
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15
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Suzuki T, Oishi N, Fukuyama H. Simultaneous infrared thermal imaging and laser speckle imaging of brain temperature and cerebral blood flow in rats. JOURNAL OF BIOMEDICAL OPTICS 2018; 24:1-11. [PMID: 30468045 PMCID: PMC6975233 DOI: 10.1117/1.jbo.24.3.031014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 11/05/2018] [Indexed: 06/09/2023]
Abstract
Infrared thermal imaging of brain temperature changes is useful for evaluating cortical activity and disease states, such as stroke. However, the changes depend on a balance between changes in heat generation from metabolism and in heat convection related to blood flow. To discriminate between these effects and gain a clearer understanding of neurovascular metabolic coupling, brain temperature imaging must be improved to measure temperature and blood flow simultaneously. We develop an imaging technique that shows a two-dimensional (2-D) distribution of absolute brain temperature and relative cerebral blood flow changes in anesthetized rats by combining infrared thermal imaging with laser speckle imaging. The changes in brain metabolism and cerebral blood flow are achieved using two different anesthetics (isoflurane and α-chloralose) to evaluate our system. Isoflurane increased cerebral blood flow but decreased metabolism, whereas α-chloralose decreased both parameters. This technique enables simultaneous visualization of brain surface changes in temperature and cerebral blood flow in the same regions. This imaging system will permit further study of neurovascular metabolic coupling in normal and diseased brains.
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Affiliation(s)
- Takashi Suzuki
- Kyoto University, Research and Educational Unit of Leaders for Integrated Medical System, Center for the Promotion of Interdisciplinary Education and Research, Kyoto, Japan
| | - Naoya Oishi
- Kyoto University, Research and Educational Unit of Leaders for Integrated Medical System, Center for the Promotion of Interdisciplinary Education and Research, Kyoto, Japan
| | - Hidenao Fukuyama
- Kyoto University, Research and Educational Unit of Leaders for Integrated Medical System, Center for the Promotion of Interdisciplinary Education and Research, Kyoto, Japan
- Beijing Institute of Technology, Human Brain Research Laboratory, Intelligent Robotics Institute, Beijing, China
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16
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Developing transmission line equations of oxygen transport for predicting oxygen distribution in the arterial system. Sci Rep 2018; 8:5369. [PMID: 29599481 PMCID: PMC5876338 DOI: 10.1038/s41598-018-23743-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 03/08/2018] [Indexed: 12/02/2022] Open
Abstract
The oxygen content in the arterial system plays a significant role in determining the physiological status of a human body. Understanding the oxygen concentration distribution in the arterial system is beneficial for the prevention and intervention of vascular disease. However, the oxygen concentration in the arteries could not be noninvasively monitored in clinical research. Although the oxygen concentration distribution in a vessel could be obtained from a three-dimensional (3D) numerical simulation of blood flow coupled with oxygen transport, a 3D numerical simulation of the systemic arterial tree is complicated and requires considerable computational resources and time. However, the lumped parameter model of oxygen transport derived from transmission line equations of oxygen transport requires fewer computational resources and less time to numerically predict the oxygen concentration distribution in the systemic arterial tree. In this study, transmission line equations of oxygen transport are developed according to the theory of oxygen transport in the vessel, and fluid transmission line equations are used as the theoretical reference for the development. The transmission line equations of oxygen transport could also be regarded as the theoretical basis for developing lumped parameter models of other substances in blood.
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17
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Linking brain vascular physiology to hemodynamic response in ultra-high field MRI. Neuroimage 2018; 168:279-295. [DOI: 10.1016/j.neuroimage.2017.02.063] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2016] [Revised: 02/20/2017] [Accepted: 02/21/2017] [Indexed: 01/05/2023] Open
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18
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Schmid F, Barrett MJP, Jenny P, Weber B. Vascular density and distribution in neocortex. Neuroimage 2017; 197:792-805. [PMID: 28669910 DOI: 10.1016/j.neuroimage.2017.06.046] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 06/09/2017] [Accepted: 06/20/2017] [Indexed: 12/22/2022] Open
Abstract
An amazingly wide range of complex behavior emerges from the cerebral cortex. Much of the information processing that leads to these behaviors is performed in neocortical circuits that span throughout the six layers of the cortex. Maintaining this circuit activity requires substantial quantities of oxygen and energy substrates, which are delivered by the complex yet well-organized and tightly-regulated vascular system. In this review, we provide a detailed characterization of the most relevant anatomical and functional features of the cortical vasculature. This includes a compilation of the available data on laminar variation of vascular density and the topological aspects of the microvascular system. We also review the spatio-temporal dynamics of cortical blood flow regulation and oxygenation, many aspects of which remain poorly understood. Finally, we discuss some of the important implications of vascular density, distribution, oxygenation and blood flow regulation for (laminar) fMRI.
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Affiliation(s)
- Franca Schmid
- Institute of Fluid Dynamics, ETH Zurich, Sonneggstrasse 3, 8092, Zurich, Switzerland.
| | - Matthew J P Barrett
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland; Neuroscience Center, University and ETH Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Patrick Jenny
- Institute of Fluid Dynamics, ETH Zurich, Sonneggstrasse 3, 8092, Zurich, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland; Neuroscience Center, University and ETH Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
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19
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Regulation of blood flow and volume exchange across the microcirculation. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2016; 20:319. [PMID: 27765054 PMCID: PMC5073467 DOI: 10.1186/s13054-016-1485-0] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Oxygen delivery to cells is the basic prerequisite of life. Within the human body, an ingenious oxygen delivery system, comprising steps of convection and diffusion from the upper airways via the lungs and the cardiovascular system to the microvascular area, bridges the gap between oxygen in the outside airspace and the interstitial space around the cells. However, the complexity of this evolutionary development makes us prone to pathophysiological problems. While those problems related to respiration and macrohemodynamics have already been successfully addressed by modern medicine, the pathophysiology of the microcirculation is still often a closed book in daily practice. Nevertheless, here as well, profound physiological understanding is the only key to rational therapeutic decisions. The prime guarantor of tissue oxygenation is tissue blood flow. Therefore, on the premise of intact macrohemodynamics, the microcirculation has three major responsibilities: 1) providing access for oxygenated blood to the tissues and appropriate return of volume; 2) maintaining global tissue flood flow, even in the face of changes in central blood pressure; and 3) linking local blood flow to local metabolic needs. It is an intriguing concept of nature to do this mainly by local regulatory mechanisms, impacting primarily on flow resistance, be this via endothelial or direct smooth muscle actions. The final goal of microvascular blood flow per unit of time is to ensure the needed exchange of substances between tissue and blood compartments. The two principle means of accomplishing this are diffusion and filtration. While simple diffusion is the quantitatively most important form of capillary exchange activity for the respiratory gases, water flux across the blood-brain barrier is facilitated via preformed specialized channels, the aquaporines. Beyond that, the vascular barrier is practically nowhere completely tight for water, with paracellular filtration giving rise to generally low but permanent fluid flux outwards into the interstitial space at the microvascular high pressure segment. At the more leaky venular aspect, both filtration and diffusion allow for bidirectional passage of water, nutrients, and waste products. We are just beginning to appreciate that a major factor for maintaining tissue fluid homeostasis appears to be the integrity of the endothelial glycocalyx.
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20
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Welter M, Fredrich T, Rinneberg H, Rieger H. Computational Model for Tumor Oxygenation Applied to Clinical Data on Breast Tumor Hemoglobin Concentrations Suggests Vascular Dilatation and Compression. PLoS One 2016; 11:e0161267. [PMID: 27547939 PMCID: PMC4993476 DOI: 10.1371/journal.pone.0161267] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 07/05/2016] [Indexed: 12/15/2022] Open
Abstract
We present a computational model for trans-vascular oxygen transport in synthetic tumor and host tissue blood vessel networks, aiming at qualitatively explaining published data of optical mammography, which were obtained from 87 breast cancer patients. The data generally show average hemoglobin concentration to be higher in tumors versus host tissue whereas average oxy-to total hemoglobin concentration (vascular segment RBC-volume-weighted blood oxygenation) can be above or below normal. Starting from a synthetic arterio-venous initial network the tumor vasculature was generated by processes involving cooption, angiogenesis, and vessel regression. Calculations of spatially resolved blood flow, hematocrit, oxy- and total hemoglobin concentrations, blood and tissue oxygenation were carried out for ninety tumor and associated normal vessel networks starting from various assumed geometries of feeding arteries and draining veins. Spatial heterogeneity in the extra-vascular partial oxygen pressure distribution can be related to various tumor compartments characterized by varying capillary densities and blood flow characteristics. The reported higher average hemoglobin concentration of tumors is explained by growth and dilatation of tumor blood vessels. Even assuming sixfold metabolic rate of oxygen consumption in tumorous versus host tissue, the predicted oxygen hemoglobin concentrations are above normal. Such tumors are likely associated with high tumor blood flow caused by high-caliber blood vessels crossing the tumor volume and hence oxygen supply exceeding oxygen demand. Tumor oxy- to total hemoglobin concentration below normal could only be achieved by reducing tumor vessel radii during growth by a randomly selected factor, simulating compression caused by intra-tumoral solid stress due to proliferation of cells and extracellular matrix. Since compression of blood vessels will impede chemotherapy we conclude that tumors with oxy- to total hemoglobin concentration below normal are less likely to respond to chemotherapy. Such behavior was recently reported for neo-adjuvant chemotherapy of locally advanced breast tumors.
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Affiliation(s)
- Michael Welter
- Theoretical Physics, Saarland University, Saarbrücken, Germany
| | | | - Herbert Rinneberg
- Division of Medical Physics and Metrological Information Technology, Physikalisch Technische Bundesanstalt PTB Berlin, Germany
| | - Heiko Rieger
- Theoretical Physics, Saarland University, Saarbrücken, Germany
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21
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Townsend D, D’Aiuto F, Deanfield J. Vascular Fragility and the Endothelial Glycocalyx in the Tissues Lining the Healthy Gingival Crevice. J Periodontol 2016; 87:672-9. [DOI: 10.1902/jop.2016.150568] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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22
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Yaseen MA, Srinivasan VJ, Gorczynska I, Fujimoto JG, Boas DA, Sakadžić S. Multimodal optical imaging system for in vivo investigation of cerebral oxygen delivery and energy metabolism. BIOMEDICAL OPTICS EXPRESS 2015; 6:4994-5007. [PMID: 26713212 PMCID: PMC4679272 DOI: 10.1364/boe.6.004994] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 11/09/2015] [Accepted: 11/14/2015] [Indexed: 05/09/2023]
Abstract
Improving our understanding of brain function requires novel tools to observe multiple physiological parameters with high resolution in vivo. We have developed a multimodal imaging system for investigating multiple facets of cerebral blood flow and metabolism in small animals. The system was custom designed and features multiple optical imaging capabilities, including 2-photon and confocal lifetime microscopy, optical coherence tomography, laser speckle imaging, and optical intrinsic signal imaging. Here, we provide details of the system's design and present in vivo observations of multiple metrics of cerebral oxygen delivery and energy metabolism, including oxygen partial pressure, microvascular blood flow, and NADH autofluorescence.
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Affiliation(s)
- Mohammad A. Yaseen
- Department of Radiology, MGH/MIT/HMS Athinuola A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts,
USA
| | - Vivek J. Srinivasan
- Department of Radiology, MGH/MIT/HMS Athinuola A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts,
USA
- Current Affiliation: Department of Biomedical Engineering, University of California, Davis, Davis, California,
USA
| | - Iwona Gorczynska
- Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts,
USA
- Current Affiliation: Department of Biophysics and Medical Physics, Institute of Physics, Nicolaus Copernicus University, Torun,
Poland
| | - James G. Fujimoto
- Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts,
USA
| | - David A. Boas
- Department of Radiology, MGH/MIT/HMS Athinuola A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts,
USA
| | - Sava Sakadžić
- Department of Radiology, MGH/MIT/HMS Athinuola A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts,
USA
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23
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Enger R, Tang W, Vindedal GF, Jensen V, Johannes Helm P, Sprengel R, Looger LL, Nagelhus EA. Dynamics of Ionic Shifts in Cortical Spreading Depression. Cereb Cortex 2015; 25:4469-76. [PMID: 25840424 PMCID: PMC4816793 DOI: 10.1093/cercor/bhv054] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Cortical spreading depression is a slowly propagating wave of near-complete depolarization of brain cells followed by temporary suppression of neuronal activity. Accumulating evidence indicates that cortical spreading depression underlies the migraine aura and that similar waves promote tissue damage in stroke, trauma, and hemorrhage. Cortical spreading depression is characterized by neuronal swelling, profound elevation of extracellular potassium and glutamate, multiphasic blood flow changes, and drop in tissue oxygen tension. The slow speed of the cortical spreading depression wave implies that it is mediated by diffusion of a chemical substance, yet the identity of this substance and the pathway it follows are unknown. Intercellular spread between gap junction-coupled neurons or glial cells and interstitial diffusion of K(+) or glutamate have been proposed. Here we use extracellular direct current potential recordings, K(+)-sensitive microelectrodes, and 2-photon imaging with ultrasensitive Ca(2+) and glutamate fluorescent probes to elucidate the spatiotemporal dynamics of ionic shifts associated with the propagation of cortical spreading depression in the visual cortex of adult living mice. Our data argue against intercellular spread of Ca(2+) carrying the cortical spreading depression wavefront and are in favor of interstitial K(+) diffusion, rather than glutamate diffusion, as the leading event in cortical spreading depression.
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Affiliation(s)
- Rune Enger
- Department of Neurology, Oslo University Hospital, 0027 Oslo, Norway
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway
- Department of Molecular Medicine, Letten Centre and GliaLab, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway
| | - Wannan Tang
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway
- Department of Molecular Medicine, Letten Centre and GliaLab, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway
- Department of Molecular Neurobiology, Max Planck Institute for Medical Research, D69120 Heidelberg, Germany
| | - Gry Fluge Vindedal
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway
- Department of Molecular Medicine, Letten Centre and GliaLab, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway
| | - Vidar Jensen
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway
- Department of Molecular Medicine, Letten Centre and GliaLab, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway
| | - P. Johannes Helm
- Department of Molecular Medicine, Letten Centre and GliaLab, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway
| | - Rolf Sprengel
- Department of Molecular Neurobiology, Max Planck Institute for Medical Research, D69120 Heidelberg, Germany
| | - Loren L. Looger
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Erlend A. Nagelhus
- Department of Neurology, Oslo University Hospital, 0027 Oslo, Norway
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway
- Department of Molecular Medicine, Letten Centre and GliaLab, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway
- Department of Molecular Neurobiology, Max Planck Institute for Medical Research, D69120 Heidelberg, Germany
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24
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Lin AJ, Ponticorvo A, Durkin AJ, Venugopalan V, Choi B, Tromberg BJ. Differential pathlength factor informs evoked stimulus response in a mouse model of Alzheimer's disease. NEUROPHOTONICS 2015; 2:045001. [PMID: 26835482 PMCID: PMC4718154 DOI: 10.1117/1.nph.2.4.045001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 09/15/2015] [Indexed: 05/03/2023]
Abstract
Baseline optical properties are typically assumed in calculating the differential pathlength factor (DPF) of mouse brains, a value used in the modified Beer-Lambert law to characterize an evoked stimulus response. We used spatial frequency domain imaging to measure in vivo baseline optical properties in 20-month-old control ([Formula: see text]) and triple transgenic APP/PS1/tau (3xTg-AD) ([Formula: see text]) mouse brains. Average [Formula: see text] for control and 3xTg-AD mice was [Formula: see text] and [Formula: see text], respectively, at 460 nm; and [Formula: see text] and [Formula: see text], respectively, at 530 nm. Average [Formula: see text] for control and 3xTg-AD mice was [Formula: see text] and [Formula: see text], respectively, at 460 nm; and [Formula: see text] and [Formula: see text], respectively, at 530 nm. The calculated DPF for control and 3xTg-AD mice was [Formula: see text] and [Formula: see text] OD mm, respectively, at 460 nm; and [Formula: see text] and [Formula: see text] OD mm, respectively, at 530 nm. In hindpaw stimulation experiments, the hemodynamic increase in brain tissue concentration of oxyhemoglobin was threefold larger and two times longer in the control mice compared to 3xTg-AD mice. Furthermore, the washout of deoxyhemoglobin from increased brain perfusion was seven times larger in controls compared to 3xTg-AD mice ([Formula: see text]).
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Affiliation(s)
- Alexander J. Lin
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, 1002 Health Sciences Road, Irvine, California 92612, United States
- University of California, Irvine, Department of Biomedical Engineering, 3120 Natural Sciences II, Irvine, California 92697-2715, United States
| | - Adrien Ponticorvo
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, 1002 Health Sciences Road, Irvine, California 92612, United States
| | - Anthony J. Durkin
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, 1002 Health Sciences Road, Irvine, California 92612, United States
| | - Vasan Venugopalan
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, 1002 Health Sciences Road, Irvine, California 92612, United States
- University of California, Irvine, Department of Chemical Engineering and Materials Science, 916 Engineering Tower, Irvine, California 92697-2575, United States
| | - Bernard Choi
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, 1002 Health Sciences Road, Irvine, California 92612, United States
- University of California, Irvine, Department of Biomedical Engineering, 3120 Natural Sciences II, Irvine, California 92697-2715, United States
- University of California, Irvine, Edwards Lifesciences Center for Advanced Cardiovascular Technology, 2400 Engineering Hall, Irvine, California 92697-2730, United States
| | - Bruce J. Tromberg
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, 1002 Health Sciences Road, Irvine, California 92612, United States
- University of California, Irvine, Department of Biomedical Engineering, 3120 Natural Sciences II, Irvine, California 92697-2715, United States
- Address all correspondence to: Bruce J. Tromberg, E-mail:
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25
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Gould IG, Linninger AA. Hematocrit distribution and tissue oxygenation in large microcirculatory networks. Microcirculation 2015; 22:1-18. [PMID: 25040825 DOI: 10.1111/micc.12156] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 06/11/2014] [Accepted: 07/15/2014] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Oxygen tension in the brain is controlled by the microcirculatory supply of RBC, but the effect of non-Newtonian blood flow rheology on tissue oxygenation is not well characterized. This study assesses different biphasic blood flow models for predicting tissue oxygen tension as a function of microcirculatory hemodynamics. METHODS Two existing plasma-skimming laws are compared against measured RBC distributions in rat and hamster microcirculatory networks. A novel biphasic blood flow model is introduced. The computational models predict tissue oxygenation in the mesentery, cremaster muscle, and the human secondary cortex. RESULTS This investigation shows deficiencies in prior models, including inconsistent plasma-skimming trends and insufficient oxygen perfusion due to the high prevalence (33%) of RBC-free microvessels. Our novel method yields physiologically sound RBC distributions and tissue oxygen tensions within one standard deviation of experimental measurements. CONCLUSIONS A simple, novel biphasic blood flow model is introduced with equal or better predictive power when applied to historic raw data sets. It can overcome limitations of prior models pertaining to trifurcations, anastomoses, and loops. This new plasma-skimming law eases the computations of bulk blood flow and hematocrit fields in large microcirculatory networks and converges faster than prior procedures.
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Affiliation(s)
- Ian G Gould
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, USA
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26
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Maeda A, Kulbatski I, DaCosta RS. Emerging Applications for Optically Enabled Intravital Microscopic Imaging in Radiobiology. Mol Imaging 2015. [DOI: 10.2310/7290.2015.00022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Azusa Maeda
- From the Princess Margaret Cancer Centre, University Health Network, MaRS Centre; Techna Institute for Advancement of Technologies for Health; and Department of Medical Biophysics, University of Toronto, MaRS Centre, Toronto, ON
| | - Iris Kulbatski
- From the Princess Margaret Cancer Centre, University Health Network, MaRS Centre; Techna Institute for Advancement of Technologies for Health; and Department of Medical Biophysics, University of Toronto, MaRS Centre, Toronto, ON
| | - Ralph S. DaCosta
- From the Princess Margaret Cancer Centre, University Health Network, MaRS Centre; Techna Institute for Advancement of Technologies for Health; and Department of Medical Biophysics, University of Toronto, MaRS Centre, Toronto, ON
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27
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Quantifying the microvascular origin of BOLD-fMRI from first principles with two-photon microscopy and an oxygen-sensitive nanoprobe. J Neurosci 2015; 35:3663-75. [PMID: 25716864 DOI: 10.1523/jneurosci.3555-14.2015] [Citation(s) in RCA: 156] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The blood oxygenation level-dependent (BOLD) contrast is widely used in functional magnetic resonance imaging (fMRI) studies aimed at investigating neuronal activity. However, the BOLD signal reflects changes in blood volume and oxygenation rather than neuronal activity per se. Therefore, understanding the transformation of microscopic vascular behavior into macroscopic BOLD signals is at the foundation of physiologically informed noninvasive neuroimaging. Here, we use oxygen-sensitive two-photon microscopy to measure the BOLD-relevant microvascular physiology occurring within a typical rodent fMRI voxel and predict the BOLD signal from first principles using those measurements. The predictive power of the approach is illustrated by quantifying variations in the BOLD signal induced by the morphological folding of the human cortex. This framework is then used to quantify the contribution of individual vascular compartments and other factors to the BOLD signal for different magnet strengths and pulse sequences.
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28
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Barrett MJ, Suresh V. Improving estimates of the cerebral metabolic rate of oxygen from optical imaging data. Neuroimage 2015; 106:101-10. [DOI: 10.1016/j.neuroimage.2014.11.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 10/27/2014] [Accepted: 11/18/2014] [Indexed: 01/26/2023] Open
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29
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Huber L, Goense J, Kennerley AJ, Ivanov D, Krieger SN, Lepsien J, Trampel R, Turner R, Möller HE. Investigation of the neurovascular coupling in positive and negative BOLD responses in human brain at 7 T. Neuroimage 2014; 97:349-62. [PMID: 24742920 DOI: 10.1016/j.neuroimage.2014.04.022] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 04/02/2014] [Accepted: 04/07/2014] [Indexed: 12/14/2022] Open
Abstract
Decreases in stimulus-dependent blood oxygenation level dependent (BOLD) signal and their underlying neurovascular origins have recently gained considerable interest. In this study a multi-echo, BOLD-corrected vascular space occupancy (VASO) functional magnetic resonance imaging (fMRI) technique was used to investigate neurovascular responses during stimuli that elicit positive and negative BOLD responses in human brain at 7 T. Stimulus-induced BOLD, cerebral blood volume (CBV), and cerebral blood flow (CBF) changes were measured and analyzed in 'arterial' and 'venous' blood compartments in macro- and microvasculature. We found that the overall interplay of mean CBV, CBF and BOLD responses is similar for tasks inducing positive and negative BOLD responses. Some aspects of the neurovascular coupling however, such as the temporal response, cortical depth dependence, and the weighting between 'arterial' and 'venous' contributions, are significantly different for the different task conditions. Namely, while for excitatory tasks the BOLD response peaks at the cortical surface, and the CBV change is similar in cortex and pial vasculature, inhibitory tasks are associated with a maximum negative BOLD response in deeper layers, with CBV showing strong constriction of surface arteries and a faster return to baseline. The different interplays of CBV, CBF and BOLD during excitatory and inhibitory responses suggests different underlying hemodynamic mechanisms.
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Affiliation(s)
- Laurentius Huber
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
| | - Jozien Goense
- Max Planck Institute for Biological Cybernetics, Tübingen, Germany; Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
| | - Aneurin J Kennerley
- Signal Processing in Neuroimaging and Systems Neuroscience, University of Sheffield, UK
| | - Dimo Ivanov
- Maastricht Brain Imaging Centre, Maastricht University, Maastricht, The Netherlands
| | - Steffen N Krieger
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; Monash Biomedical Imaging, Monash University, Melbourne, Victoria, Australia
| | - Jöran Lepsien
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Robert Trampel
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Robert Turner
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Harald E Möller
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
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30
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Barrett MJP, Suresh V. Extra permeability is required to model dynamic oxygen measurements: evidence for functional recruitment? J Cereb Blood Flow Metab 2013; 33:1402-11. [PMID: 23673433 PMCID: PMC3764383 DOI: 10.1038/jcbfm.2013.74] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 02/14/2013] [Accepted: 04/02/2013] [Indexed: 01/29/2023]
Abstract
Neural activation triggers a rapid, focal increase in blood flow and thus oxygen delivery. Local oxygen consumption also increases, although not to the same extent as oxygen delivery. This 'uncoupling' enables a number of widely-used functional neuroimaging techniques; however, the physiologic mechanisms that govern oxygen transport under these conditions remain unclear. Here, we explore this dynamic process using a new mathematical model. Motivated by experimental observations and previous modeling, we hypothesized that functional recruitment of capillaries has an important role during neural activation. Using conventional mechanisms alone, the model predictions were inconsistent with in vivo measurements of oxygen partial pressure. However, dynamically increasing net capillary permeability, a simple description of functional recruitment, led to predictions consistent with the data. Increasing permeability in all vessel types had the same effect, but two alternative mechanisms were unable to produce predictions consistent with the data. These results are further evidence that conventional models of oxygen transport are not sufficient to predict dynamic experimental data. The data and modeling suggest that it is necessary to include a mechanism that dynamically increases net vascular permeability. While the model cannot distinguish between the different possibilities, we speculate that functional recruitment could have this effect in vivo.
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Affiliation(s)
- Matthew J P Barrett
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand.
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31
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Cucullo L, Hossain M, Tierney W, Janigro D. A new dynamic in vitro modular capillaries-venules modular system: cerebrovascular physiology in a box. BMC Neurosci 2013; 14:18. [PMID: 23388041 PMCID: PMC3598202 DOI: 10.1186/1471-2202-14-18] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Accepted: 01/25/2013] [Indexed: 01/30/2023] Open
Abstract
Background The study of the cerebrovascular physiology is crucial to understand the pathogenesis of neurological disease and the pharmacokinetic of drugs. Appropriate models in vitro often fail to represent in vivo physiology. To address these issues we propose the use of a novel artificial vascular system that closely mimics capillary and venous segments of human cerebrovasculature while also allowing for an extensive control of the experimental variables and their manipulation. Results Using hollow fiber technology, we modified an existing dynamic artificial model of the blood–brain barrier (BBB) (DIV-capillary) to encompass the distal post-capillary (DIV-venules) segments of the brain circulatory system. This artificial brain vascular system is comprised of a BBB module serially connected to a venule segment. A pump generates a pulsatile flow with arterial pressure feeding the system. The perfusate of the capillary module achieves levels of shear stress, pressure, and flow rate comparable to what observed in situ. Endothelial cell exposure to flow and abluminal astrocytic stimuli allowed for the formation of a highly selective capillary BBB with a trans-endothelial electrical resistance (TEER; >700 ohm cm2) and sucrose permeability (< 1X10-u cm/sec) comparable to in vivo. The venule module, which attempted to reproduce features of the hemodynamic microenvironment of venules, was perfused by media resulting in shear stress and intraluminal pressure levels lower than those found in capillaries. Because of altered cellular and hemodynamic factors, venule segments present a less stringent vascular bed (TEER <250 Ohm cm2; Psucrose > 1X10-4 cm/sec) than that of the BBB. Abluminal human brain vascular smooth muscle cells were used to reproduce the venular abluminal cell composition. Conclusion The unique characteristics afforded by the DIV-BBB in combination with a venule segment will realistically expand our ability to dissect and study the physiological and functional behavior of distinct segments of the human cerebrovascular network.
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Affiliation(s)
- Luca Cucullo
- Cerebrovascular Research, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
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32
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Yaseen MA, Sakadžić S, Wu W, Becker W, Kasischke KA, Boas DA. In vivo imaging of cerebral energy metabolism with two-photon fluorescence lifetime microscopy of NADH. BIOMEDICAL OPTICS EXPRESS 2013; 4:307-21. [PMID: 23412419 PMCID: PMC3567717 DOI: 10.1364/boe.4.000307] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 01/17/2013] [Accepted: 01/17/2013] [Indexed: 05/04/2023]
Abstract
Minimally invasive, specific measurement of cellular energy metabolism is crucial for understanding cerebral pathophysiology. Here, we present high-resolution, in vivo observations of autofluorescence lifetime as a biomarker of cerebral energy metabolism in exposed rat cortices. We describe a customized two-photon imaging system with time correlated single photon counting detection and specialized software for modeling multiple-component fits of fluorescence decay and monitoring their transient behaviors. In vivo cerebral NADH fluorescence suggests the presence of four distinct components, which respond differently to brief periods of anoxia and likely indicate different enzymatic formulations. Individual components show potential as indicators of specific molecular pathways involved in oxidative metabolism.
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Affiliation(s)
- Mohammad A. Yaseen
- Optics Division, MGH/MIT/HMS Athinoula A. Martinos Center for
Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School, Charlestown,
Massachusetts 02129, USA
| | - Sava Sakadžić
- Optics Division, MGH/MIT/HMS Athinoula A. Martinos Center for
Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School, Charlestown,
Massachusetts 02129, USA
| | - Weicheng Wu
- Optics Division, MGH/MIT/HMS Athinoula A. Martinos Center for
Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School, Charlestown,
Massachusetts 02129, USA
| | - Wolfgang Becker
- Becker & Hickl GmbH, Nahmitzer Damm 30, 12277 Berlin,
Germany
| | - Karl A. Kasischke
- Department of Neurology, University of Ulm Medical Center, Oberer
Eselsberg 45, 89075 Ulm, Germany
| | - David A. Boas
- Optics Division, MGH/MIT/HMS Athinoula A. Martinos Center for
Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School, Charlestown,
Massachusetts 02129, USA
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33
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Baker WB, Sun Z, Hiraki T, Putt ME, Durduran T, Reivich M, Yodh AG, Greenberg JH. Neurovascular coupling varies with level of global cerebral ischemia in a rat model. J Cereb Blood Flow Metab 2013; 33:97-105. [PMID: 23032485 PMCID: PMC3597370 DOI: 10.1038/jcbfm.2012.137] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In this study, cerebral blood flow, oxygenation, metabolic, and electrical functional responses to forepaw stimulation were monitored in rats at different levels of global cerebral ischemia from mild to severe. Laser speckle contrast imaging and optical imaging of intrinsic signals were used to measure changes in blood flow and oxygenation, respectively, along with a compartmental model to calculate changes in oxygen metabolism from these measured changes. To characterize the electrical response to functional stimulation, we measured somatosensory evoked potentials (SEPs). Global graded ischemia was induced through unilateral carotid artery occlusion, bilateral carotid artery occlusion, bilateral carotid and right subclavian artery (SCA) occlusion, or carotid and SCA occlusion with negative lower body pressure. We found that the amplitude of the functional metabolic response remained tightly coupled to the amplitude of the SEP at all levels of ischemia observed. However, as the level of ischemia became more severe, the flow response was more strongly attenuated than the electrical response, suggesting that global ischemia was associated with an uncoupling between the functional flow and electrical responses.
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Affiliation(s)
- Wesley B Baker
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA.
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34
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Dalkara T, Arsava EM. Can restoring incomplete microcirculatory reperfusion improve stroke outcome after thrombolysis? J Cereb Blood Flow Metab 2012; 32:2091-9. [PMID: 23047270 PMCID: PMC3519416 DOI: 10.1038/jcbfm.2012.139] [Citation(s) in RCA: 162] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 08/31/2012] [Accepted: 09/03/2012] [Indexed: 12/27/2022]
Abstract
Substantial experimental data and recent clinical evidence suggesting that tissue reperfusion is a better predictor of outcome after thrombolysis than recanalization necessitate that patency of microcirculation after recanalization should be reevaluated. If indeed microcirculatory blood flow cannot be sufficiently reinstituted despite complete recanalization as commonly observed in coronary circulation, it may be one of the factors contributing to low efficacy of thrombolysis in stroke. Although microvascular no-reflow is considered an irreversible process that prevents tissue recovery from injury, emerging evidence suggests that it might be reversed with pharmacological agents administered early during recanalization. Therefore, therapeutic approaches aiming at reducing microvascular obstructions may improve success rate of recanalization therapies. Importantly, promoting oxygen delivery to the tissue, where entrapped erythrocytes cannot circulate in capillaries, with ongoing serum flow may improve survival of the underreperfused tissue. Altogether, these developments bring about the exciting possibility that benefit of reperfusion therapies can be further improved by restoring microcirculatory function because survival in the penumbra critically depends on adequate blood supply. Here, we review the available evidence suggesting presence of an 'incomplete microcirculatory reperfusion' (IMR) after focal cerebral ischemia and discuss potential means that may help investigate IMR in stroke patients after recanalization therapies despite technical limitations.
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Affiliation(s)
- Turgay Dalkara
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey.
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35
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Bolmont T, Bouwens A, Pache C, Dimitrov M, Berclaz C, Villiger M, Wegenast-Braun BM, Lasser T, Fraering PC. Label-free imaging of cerebral β-amyloidosis with extended-focus optical coherence microscopy. J Neurosci 2012; 32:14548-56. [PMID: 23077040 PMCID: PMC6621450 DOI: 10.1523/jneurosci.0925-12.2012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 08/16/2012] [Accepted: 08/22/2012] [Indexed: 12/16/2022] Open
Abstract
We demonstrate label-free imaging of cerebral β-amyloidosis ex vivo and in a living mouse model of Alzheimer's disease using extended-focus Fourier domain optical coherence microscopy (xfOCM). xfOCM provides 3D, high-resolution images of individual β-amyloid plaques in the brain parenchyma and vasculature and requires no staining of the alzheimeric sample under investigation. xfOCM also opens the possibility to perform minimally invasive studies of β-amyloid pathology in vivo, without the use of labeling methods, which potentially confound experimental findings.
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Affiliation(s)
- Tristan Bolmont
- Laboratory of Molecular and Cellular Biology of Alzheimer's Disease, Brain Mind Institute and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland
- Laboratoire d'optique Biomédicale, Institute of Microengineering, School of Engineering, EPFL, CH1015 Lausanne, Switzerland
| | - Arno Bouwens
- Laboratoire d'optique Biomédicale, Institute of Microengineering, School of Engineering, EPFL, CH1015 Lausanne, Switzerland
| | - Christophe Pache
- Laboratoire d'optique Biomédicale, Institute of Microengineering, School of Engineering, EPFL, CH1015 Lausanne, Switzerland
| | - Mitko Dimitrov
- Laboratory of Molecular and Cellular Biology of Alzheimer's Disease, Brain Mind Institute and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland
| | - Corinne Berclaz
- Laboratoire d'optique Biomédicale, Institute of Microengineering, School of Engineering, EPFL, CH1015 Lausanne, Switzerland
| | - Martin Villiger
- Laboratoire d'optique Biomédicale, Institute of Microengineering, School of Engineering, EPFL, CH1015 Lausanne, Switzerland
| | - Bettina M. Wegenast-Braun
- Department of Cellular Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, DE72076 Tübingen, Germany; and
- DZNE–German Center for Neurodegenerative Diseases, DE72076 Tübingen, Germany
| | - Theo Lasser
- Laboratoire d'optique Biomédicale, Institute of Microengineering, School of Engineering, EPFL, CH1015 Lausanne, Switzerland
| | - Patrick C. Fraering
- Laboratory of Molecular and Cellular Biology of Alzheimer's Disease, Brain Mind Institute and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland
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36
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Devor A, Sakadžić S, Srinivasan VJ, Yaseen MA, Nizar K, Saisan PA, Tian P, Dale AM, Vinogradov SA, Franceschini MA, Boas DA. Frontiers in optical imaging of cerebral blood flow and metabolism. J Cereb Blood Flow Metab 2012; 32:1259-76. [PMID: 22252238 PMCID: PMC3390808 DOI: 10.1038/jcbfm.2011.195] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In vivo optical imaging of cerebral blood flow (CBF) and metabolism did not exist 50 years ago. While point optical fluorescence and absorption measurements of cellular metabolism and hemoglobin concentrations had already been introduced by then, point blood flow measurements appeared only 40 years ago. The advent of digital cameras has significantly advanced two-dimensional optical imaging of neuronal, metabolic, vascular, and hemodynamic signals. More recently, advanced laser sources have enabled a variety of novel three-dimensional high-spatial-resolution imaging approaches. Combined, as we discuss here, these methods are permitting a multifaceted investigation of the local regulation of CBF and metabolism with unprecedented spatial and temporal resolution. Through multimodal combination of these optical techniques with genetic methods of encoding optical reporter and actuator proteins, the future is bright for solving the mysteries of neurometabolic and neurovascular coupling and translating them to clinical utility.
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Affiliation(s)
- Anna Devor
- Department of Neurosciences, UCSD, La Jolla, CA, USA.
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37
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Lee KKC, Mariampillai A, Yu JXZ, Cadotte DW, Wilson BC, Standish BA, Yang VXD. Real-time speckle variance swept-source optical coherence tomography using a graphics processing unit. BIOMEDICAL OPTICS EXPRESS 2012; 3:1557-64. [PMID: 22808428 PMCID: PMC3395481 DOI: 10.1364/boe.3.001557] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Revised: 05/30/2012] [Accepted: 06/05/2012] [Indexed: 05/20/2023]
Abstract
Advances in swept source laser technology continues to increase the imaging speed of swept-source optical coherence tomography (SS-OCT) systems. These fast imaging speeds are ideal for microvascular detection schemes, such as speckle variance (SV), where interframe motion can cause severe imaging artifacts and loss of vascular contrast. However, full utilization of the laser scan speed has been hindered by the computationally intensive signal processing required by SS-OCT and SV calculations. Using a commercial graphics processing unit that has been optimized for parallel data processing, we report a complete high-speed SS-OCT platform capable of real-time data acquisition, processing, display, and saving at 108,000 lines per second. Subpixel image registration of structural images was performed in real-time prior to SV calculations in order to reduce decorrelation from stationary structures induced by the bulk tissue motion. The viability of the system was successfully demonstrated in a high bulk tissue motion scenario of human fingernail root imaging where SV images (512 × 512 pixels, n = 4) were displayed at 54 frames per second.
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Affiliation(s)
- Kenneth K. C. Lee
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario, Canada
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada
- These authors contributed equally to this work
| | - Adrian Mariampillai
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada
- These authors contributed equally to this work
| | - Joe X. Z. Yu
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada
| | - David W. Cadotte
- Division of Neurosurgery, Toronto Western Hospital, Toronto, Ontario, Canada
- Instite of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Krembil Neuroscience Centre, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - Brian C. Wilson
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Beau A. Standish
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada
| | - Victor X. D. Yang
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario, Canada
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada
- Department of Medical Imaging, St. Michael’s Hospital, Toronto, Ontario, Canada
- Division of Neurosurgery, St. Michael’s Hospital, Toronto, Ontario, Canada
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38
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Hirsch S, Reichold J, Schneider M, Székely G, Weber B. Topology and hemodynamics of the cortical cerebrovascular system. J Cereb Blood Flow Metab 2012; 32:952-67. [PMID: 22472613 PMCID: PMC3367227 DOI: 10.1038/jcbfm.2012.39] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The cerebrovascular system continuously delivers oxygen and energy substrates to the brain, which is one of the organs with the highest basal energy requirement in mammals. Discontinuities in the delivery lead to fatal consequences for the brain tissue. A detailed understanding of the structure of the cerebrovascular system is important for a multitude of (patho-)physiological cerebral processes and many noninvasive functional imaging methods rely on a signal that originates from the vasculature. Furthermore, neurodegenerative diseases often involve the cerebrovascular system and could contribute to neuronal loss. In this review, we focus on the cortical vascular system. In the first part, we present the current knowledge of the vascular anatomy. This is followed by a theory of topology and its application to vascular biology. We then discuss possible interactions between cerebral blood flow and vascular topology, before summarizing the existing body of the literature on quantitative cerebrovascular topology.
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Affiliation(s)
- Sven Hirsch
- Computer Vision Laboratory, Federal Institute of Technology ETH, Zurich, Switzerland
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39
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Kennerley AJ, Mayhew JE, Boorman L, Zheng Y, Berwick J. Is optical imaging spectroscopy a viable measurement technique for the investigation of the negative BOLD phenomenon? A concurrent optical imaging spectroscopy and fMRI study at high field (7 T). Neuroimage 2012; 61:10-20. [PMID: 22440642 PMCID: PMC3368428 DOI: 10.1016/j.neuroimage.2012.03.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 02/16/2012] [Accepted: 03/06/2012] [Indexed: 02/05/2023] Open
Abstract
Traditionally functional magnetic resonance imaging (fMRI) has been used to map activity in the human brain by measuring increases in the Blood Oxygenation Level Dependent (BOLD) signal. Often accompanying positive BOLD fMRI signal changes are sustained negative signal changes. Previous studies investigating the neurovascular coupling mechanisms of the negative BOLD phenomenon have used concurrent 2D-optical imaging spectroscopy (2D-OIS) and electrophysiology (Boorman et al., 2010). These experiments suggested that the negative BOLD signal in response to whisker stimulation was a result of an increase in deoxy-haemoglobin and reduced multi-unit activity in the deep cortical layers. However, Boorman et al. (2010) did not measure the BOLD and haemodynamic response concurrently and so could not quantitatively compare either the spatial maps or the 2D-OIS and fMRI time series directly. Furthermore their study utilised a homogeneous tissue model in which is predominantly sensitive to haemodynamic changes in more superficial layers. Here we test whether the 2D-OIS technique is appropriate for studies of negative BOLD. We used concurrent fMRI with 2D-OIS techniques for the investigation of the haemodynamics underlying the negative BOLD at 7 Tesla. We investigated whether optical methods could be used to accurately map and measure the negative BOLD phenomenon by using 2D-OIS haemodynamic data to derive predictions from a biophysical model of BOLD signal changes. We showed that despite the deep cortical origin of the negative BOLD response, if an appropriate heterogeneous tissue model is used in the spectroscopic analysis then 2D-OIS can be used to investigate the negative BOLD phenomenon.
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Affiliation(s)
- Aneurin J Kennerley
- Centre for Signal Processing in Neuroimaging and Systems Neuroscience (SPiNSN), Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
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40
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Yuzawa I, Sakadžić S, Srinivasan VJ, Shin HK, Eikermann-Haerter K, Boas DA, Ayata C. Cortical spreading depression impairs oxygen delivery and metabolism in mice. J Cereb Blood Flow Metab 2012; 32:376-86. [PMID: 22008729 PMCID: PMC3272607 DOI: 10.1038/jcbfm.2011.148] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 08/26/2011] [Accepted: 09/20/2011] [Indexed: 01/28/2023]
Abstract
Cortical spreading depression (CSD) is associated with severe hypoperfusion in mice. Using minimally invasive multimodal optical imaging, we show that severe flow reductions during and after spreading depression are associated with a steep decline in cerebral metabolic rate of oxygen. Concurrent severe hemoglobin desaturation suggests that the oxygen metabolism becomes at least in part supply limited, and the decrease in cortical blood volume implicates vasoconstriction as the mechanism. In support of oxygen supply-demand mismatch, cortical nicotinamide adenine dinucleotide (NADH) fluorescence increases during spreading depression for at least 5 minutes, particularly away from parenchymal arterioles. However, modeling of tissue oxygen delivery shows that cerebral metabolic rate of oxygen drops more than predicted by a purely supply-limited model, raising the possibility of a concurrent reduction in oxygen demand during spreading depression. Importantly, a subsequent spreading depression triggered within 15 minutes evokes a monophasic flow increase superimposed on the oligemic baseline, which markedly differs from the response to the preceding spreading depression triggered in naive cortex. Altogether, these data suggest that CSD is associated with long-lasting oxygen supply-demand mismatch linked to severe vasoconstriction in mice.
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Affiliation(s)
- Izumi Yuzawa
- Department of Radiology, Neurovascular Research Laboratory, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA
| | - Sava Sakadžić
- Optics Division, MGH/MIT/HMS Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA
| | - Vivek J Srinivasan
- Optics Division, MGH/MIT/HMS Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA
| | - Hwa Kyoung Shin
- Department of Radiology, Neurovascular Research Laboratory, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA
| | - Katharina Eikermann-Haerter
- Department of Radiology, Neurovascular Research Laboratory, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA
| | - David A Boas
- Optics Division, MGH/MIT/HMS Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA
| | - Cenk Ayata
- Department of Radiology, Neurovascular Research Laboratory, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA
- Stroke Service and Neuroscience Intensive Care Unit, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
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41
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Heterogeneity in the rat brain vasculature revealed by quantitative confocal analysis of endothelial barrier antigen and P-glycoprotein expression. J Cereb Blood Flow Metab 2012; 32:81-92. [PMID: 21792241 PMCID: PMC3323292 DOI: 10.1038/jcbfm.2011.109] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
While phenotypic endothelial heterogeneity is well documented in peripheral organs, it is only now being explored in the brain. We used confocal imaging of thick sections of rat brain to qualitatively and quantitatively examine the expression of two key markers of the blood-brain barrier (BBB) in the rat, P-glycoprotein (P-gp), and endothelial barrier antigen (EBA). We found that these markers were not uniformly distributed throughout the whole vasculature of the cortex and hippocampus. P-glycoprotein displayed a gradient of expression from an almost undetectable level in large penetrating arterioles to a high and uniform level in capillaries and venules. While EBA was lacking in all cerebral arterioles, regardless of their size, its expression varied greatly among endothelial cells in capillaries and venules, yielding a striking mosaic pattern. A detailed quantitative analysis of the distribution of these markers at the single cell level in capillaries is provided. These results challenge the view of a uniform BBB and suggest that regulatory mechanisms might differentially modulate BBB features not only among arterioles/capillaries/venules but also at the single cell level within the capillaries. Hypotheses are made regarding the underlying mechanisms and physiopathological consequences of this heterogeneity.
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Davis MA, Shams Kazmi SM, Ponticorvo A, Dunn AK. Depth dependence of vascular fluorescence imaging. BIOMEDICAL OPTICS EXPRESS 2011; 2:3349-62. [PMID: 22162824 PMCID: PMC3233253 DOI: 10.1364/boe.2.003349] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Revised: 11/01/2011] [Accepted: 11/15/2011] [Indexed: 05/19/2023]
Abstract
In vivo surface imaging of fluorescently labeled vasculature has become a widely used tool for functional brain imaging studies. Techniques such as phosphorescence quenching for oxygen tension measurements and indocyanine green fluorescence for vessel perfusion monitoring rely on surface measurements of vascular fluorescence. However, the depth dependence of the measured fluorescence signals has not been modeled in great detail. In this paper, we investigate the depth dependence of the measured signals using a three-dimensional Monte Carlo model combined with high resolution vascular anatomy. We found that a bulk-vascularization assumption to modeling the depth dependence of the signal does not provide an accurate picture of penetration depth of the collected fluorescence signal in most cases. Instead the physical distribution of microvasculature, the degree of absorption difference between extravascular and intravascular space, and the overall difference in absorption at the excitation and emission wavelengths must be taken into account to determine the depth penetration of the fluorescence signal. Additionally, we found that using targeted illumination can provide for superior surface vessel sensitivity over wide-field illumination, with small area detection offering an even greater amount of sensitivity to surface vasculature. Depth sensitivity can be enhanced by either increasing the detector area or increasing the illumination area. Finally, we see that excitation wavelength and vessel size can affect intra-vessel sampling distribution, as well as the amount of signal that originates from inside the vessel under targeted illumination conditions.
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Affiliation(s)
- Mitchell A. Davis
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712,
USA
| | - S. M. Shams Kazmi
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712,
USA
| | - Adrien Ponticorvo
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712,
USA
| | - Andrew K. Dunn
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712,
USA
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Boas DA, Franceschini MA. Haemoglobin oxygen saturation as a biomarker: the problem and a solution. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:4407-24. [PMID: 22006898 PMCID: PMC3263786 DOI: 10.1098/rsta.2011.0250] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Near-infrared spectroscopy measures of haemoglobin oxygen saturation are often used as an indicator of sufficient oxygen delivery to assess injury susceptibility and tissue damage. They have also often been used as a surrogate measure of oxygen metabolism. Unfortunately, these measures have generally failed to provide robust indicators of injury and metabolism. In this paper, we first review when haemoglobin oxygen saturation does work as a robust indicator, and then detail when and why it fails for assessing brain injury and breast cancer. Finally, we discuss the solution to obtain more robust measures of tissue injury and cancer by combining oxygen saturation measurements with measures of blood flow and volume to more accurately estimate oxygen metabolism.
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Affiliation(s)
- David A Boas
- Optics Division of the Martinos Center for Biomedical Imaging, Harvard Medical School, Massachusetts General Hospital, 149 13th St rm 2301, Charlestown, MA 02129, USA.
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Gagnon L, Yücel MA, Dehaes M, Cooper RJ, Perdue KL, Selb J, Huppert TJ, Hoge RD, Boas DA. Quantification of the cortical contribution to the NIRS signal over the motor cortex using concurrent NIRS-fMRI measurements. Neuroimage 2011; 59:3933-40. [PMID: 22036999 DOI: 10.1016/j.neuroimage.2011.10.054] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 10/04/2011] [Accepted: 10/17/2011] [Indexed: 11/19/2022] Open
Abstract
Near-Infrared Spectroscopy (NIRS) measures the functional hemodynamic response occurring at the surface of the cortex. Large pial veins are located above the surface of the cerebral cortex. Following activation, these veins exhibit oxygenation changes but their volume likely stays constant. The back-reflection geometry of the NIRS measurement renders the signal very sensitive to these superficial pial veins. As such, the measured NIRS signal contains contributions from both the cortical region as well as the pial vasculature. In this work, the cortical contribution to the NIRS signal was investigated using (1) Monte Carlo simulations over a realistic geometry constructed from anatomical and vascular MRI and (2) multimodal NIRS-BOLD recordings during motor stimulation. A good agreement was found between the simulations and the modeling analysis of in vivo measurements. Our results suggest that the cortical contribution to the deoxyhemoglobin signal change (ΔHbR) is equal to 16-22% of the cortical contribution to the total hemoglobin signal change (ΔHbT). Similarly, the cortical contribution of the oxyhemoglobin signal change (ΔHbO) is equal to 73-79% of the cortical contribution to the ΔHbT signal. These results suggest that ΔHbT is far less sensitive to pial vein contamination and therefore, it is likely that the ΔHbT signal provides better spatial specificity and should be used instead of ΔHbO or ΔHbR to map cerebral activity with NIRS. While different stimuli will result in different pial vein contributions, our finger tapping results do reveal the importance of considering the pial contribution.
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Affiliation(s)
- Louis Gagnon
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.
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Deneux T, Takerkart S, Grinvald A, Masson GS, Vanzetta I. A processing work-flow for measuring erythrocytes velocity in extended vascular networks from wide field high-resolution optical imaging data. Neuroimage 2011; 59:2569-88. [PMID: 21925275 DOI: 10.1016/j.neuroimage.2011.08.081] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Revised: 08/19/2011] [Accepted: 08/25/2011] [Indexed: 11/19/2022] Open
Abstract
Comprehensive information on the spatio-temporal dynamics of the vascular response is needed to underpin the signals used in hemodynamics-based functional imaging. It has recently been shown that red blood cells (RBCs) velocity and its changes can be extracted from wide-field optical imaging recordings of intrinsic absorption changes in cortex. Here, we describe a complete processing work-flow for reliable RBC velocity estimation in cortical networks. Several pre-processing steps are implemented: image co-registration, necessary to correct for small movements of the vasculature, semi-automatic image segmentation for fast and reproducible vessel selection, reconstruction of RBC trajectories patterns for each micro-vessel, and spatio-temporal filtering to enhance the desired data characteristics. The main analysis step is composed of two robust algorithms for estimating the RBCs' velocity field. Vessel diameter and its changes are also estimated, as well as local changes in backscattered light intensity. This full processing chain is implemented with a software suite that is freely distributed. The software uses efficient data management for handling the very large data sets obtained with in vivo optical imaging. It offers a complete and user-friendly graphical user interface with visualization tools for displaying and exploring data and results. A full data simulation framework is also provided in order to optimize the performances of the algorithm with respect to several characteristics of the data. We illustrate the performance of our method in three different cases of in vivo data. We first document the massive RBC speed response evoked by a spreading depression in anesthetized rat somato-sensory cortex. Second, we show the velocity response elicited by a visual stimulation in anesthetized cat visual cortex. Finally, we report, for the first time, visually-evoked RBC speed responses in an extended vascular network in awake monkey extrastriate cortex.
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Affiliation(s)
- Thomas Deneux
- Institut de Neurosciences Cognitives de la Méditerranée, UMR6193, CNRS & Aix-Marseille Université, Marseille, France
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The physiology of developmental changes in BOLD functional imaging signals. Dev Cogn Neurosci 2011; 1:199-216. [PMID: 22436508 DOI: 10.1016/j.dcn.2011.04.001] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 04/18/2011] [Accepted: 04/19/2011] [Indexed: 12/14/2022] Open
Abstract
BOLD fMRI (blood oxygenation level dependent functional magnetic resonance imaging) is increasingly used to detect developmental changes of human brain function that are hypothesized to underlie the maturation of cognitive processes. BOLD signals depend on neuronal activity increasing cerebral blood flow, and are reduced by neural oxygen consumption. Thus, developmental changes of BOLD signals may not reflect altered information processing if there are concomitant changes in neurovascular coupling (the mechanism by which neuronal activity increases blood flow) or neural energy use (and hence oxygen consumption). We review how BOLD signals are generated, and explain the signalling pathways which convert neuronal activity into increased blood flow. We then summarize in broad terms the developmental changes that the brain's neural circuitry undergoes during growth from childhood through adolescence to adulthood, and present the changes in neurovascular coupling mechanisms and energy use which occur over the same period. This information provides a framework for assessing whether the BOLD changes observed during human development reflect altered cognitive processing or changes in neurovascular coupling and energy use.
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