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Broggini T, Duckworth J, Ji X, Liu R, Xia X, Mächler P, Shaked I, Munting LP, Iyengar S, Kotlikoff M, van Veluw SJ, Vergassola M, Mishne G, Kleinfeld D. Long-wavelength traveling waves of vasomotion modulate the perfusion of cortex. Neuron 2024; 112:2349-2367.e8. [PMID: 38781972 PMCID: PMC11257831 DOI: 10.1016/j.neuron.2024.04.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 03/28/2024] [Accepted: 04/30/2024] [Indexed: 05/25/2024]
Abstract
Brain arterioles are active, multicellular complexes whose diameters oscillate at ∼ 0.1 Hz. We assess the physiological impact and spatiotemporal dynamics of vaso-oscillations in the awake mouse. First, vaso-oscillations in penetrating arterioles, which source blood from pial arterioles to the capillary bed, profoundly impact perfusion throughout neocortex. The modulation in flux during resting-state activity exceeds that of stimulus-induced activity. Second, the change in perfusion through arterioles relative to the change in their diameter is weak. This implies that the capillary bed dominates the hydrodynamic resistance of brain vasculature. Lastly, the phase of vaso-oscillations evolves slowly along arterioles, with a wavelength that exceeds the span of the cortical mantle and sufficient variability to establish functional cortical areas as parcels of uniform phase. The phase-gradient supports traveling waves in either direction along both pial and penetrating arterioles. This implies that waves along penetrating arterioles can mix, but not directionally transport, interstitial fluids.
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Affiliation(s)
- Thomas Broggini
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA; Goethe University Frankfurt, Department of Neurosurgery, 60528 Frankfurt am Main, Germany; Frankfurt Cancer Institute, Goethe University Frankfurt, 60528 Frankfurt am Main, Germany
| | - Jacob Duckworth
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Xiang Ji
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Rui Liu
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Xinyue Xia
- Halıcıoğlu Data Science Institute, University of California, San Diego, La Jolla, CA 92093, USA
| | - Philipp Mächler
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Iftach Shaked
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Leon Paul Munting
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Satish Iyengar
- Department of Statistics, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Michael Kotlikoff
- College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Susanne J van Veluw
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
| | | | - Gal Mishne
- Halıcıoğlu Data Science Institute, University of California, San Diego, La Jolla, CA 92093, USA
| | - David Kleinfeld
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA; Department of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA.
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Mardanpour MM, Sudalaiyadum Perumal A, Mahmoodi Z, Baassiri K, Montiel-Rubies G, LeDez KM, Nicolau DV. Investigation of air bubble behaviour after gas embolism events induced in a microfluidic network mimicking microvasculature. LAB ON A CHIP 2024; 24:2518-2536. [PMID: 38623600 DOI: 10.1039/d4lc00087k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
Gas embolism is a medical condition that occurs when gas bubbles are present in veins or arteries, decreasing blood flow and potentially reducing oxygen delivery to vital organs, such as the brain. Although usually reported as rare, gas embolism can lead to severe neurological damage or death. However, presently, only limited understanding exists regarding the microscale processes leading to the formation, persistence, movement, and resolution of gas emboli, as modulated by microvasculature geometrical features and blood properties. Because gas embolism is initially a physico-chemical-only process, with biological responses starting later, the opportunity exists to fully study the genesis and evolution of gas emboli using in vitro microfluidic networks mimicking small regions of microvasculature. The microfluidics networks used in this study, which aim to mimic microvasculature geometry, comprise linear channels with T-, or Y-junction air inlets, with 20, 40, and 60 μm widths (arterial or venous), and a 30 μm width honeycombed network (arterial) with three bifurcation angles (30°, 60°, and 90°). Synthetic blood, equivalent to 46% haematocrit concentrations, and water were used to study the modulation of gas embolism-like events by liquid viscosity. Our study shows that (i) longer bubbles with lower velocity occur in narrower channels, e.g., with 20 μm width; (ii) the resistance of air bubbles to the flow increases with the higher haematocrit concentration; and lastly (iii) the propensity of gas embolism-like events in honeycomb architectures increases for more acute, e.g., 30°, bifurcation angles. A dimensionless analysis using Euler, Weber, and capillary numbers demarcated the conditions conducive to gas embolism. This work suggests that in vitro experimentation using microfluidic devices with microvascular tissue-like structures could assist medical guidelines and management in preventing and mitigating the effects of gas embolism.
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Affiliation(s)
- Mohammad Mahdi Mardanpour
- Department of Bioengineering, Faculty of Engineering, McGill University, Montreal, Québec, H3A 0E9, Canada.
| | | | - Zahra Mahmoodi
- Department of Bioengineering, Faculty of Engineering, McGill University, Montreal, Québec, H3A 0E9, Canada.
| | - Karine Baassiri
- Department of Bioengineering, Faculty of Engineering, McGill University, Montreal, Québec, H3A 0E9, Canada.
| | - Gala Montiel-Rubies
- Department of Bioengineering, Faculty of Engineering, McGill University, Montreal, Québec, H3A 0E9, Canada.
| | - Kenneth M LeDez
- Faculty of Medicine, Health Sciences Centre, Memorial University, St. John's, Newfoundland and Labrador, A1C 5S7, Canada
| | - Dan V Nicolau
- Department of Bioengineering, Faculty of Engineering, McGill University, Montreal, Québec, H3A 0E9, Canada.
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Song W, Beigneux AP, Weston TA, Chen K, Yang Y, Nguyen LP, Guagliardo P, Jung H, Tran AP, Tu Y, Tran C, Birrane G, Miyashita K, Nakajima K, Murakami M, Tontonoz P, Jiang H, Ploug M, Fong LG, Young SG. The lipoprotein lipase that is shuttled into capillaries by GPIHBP1 enters the glycocalyx where it mediates lipoprotein processing. Proc Natl Acad Sci U S A 2023; 120:e2313825120. [PMID: 37871217 PMCID: PMC10623010 DOI: 10.1073/pnas.2313825120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Accepted: 09/19/2023] [Indexed: 10/25/2023] Open
Abstract
Lipoprotein lipase (LPL), the enzyme that carries out the lipolytic processing of triglyceride-rich lipoproteins (TRLs), is synthesized by adipocytes and myocytes and secreted into the interstitial spaces. The LPL is then bound by GPIHBP1, a GPI-anchored protein of endothelial cells (ECs), and transported across ECs to the capillary lumen. The assumption has been that the LPL that is moved into capillaries remains attached to GPIHBP1 and that GPIHBP1 serves as a platform for TRL processing. In the current studies, we examined the validity of that assumption. We found that an LPL-specific monoclonal antibody (mAb), 88B8, which lacks the ability to detect GPIHBP1-bound LPL, binds avidly to LPL within capillaries. We further demonstrated, by confocal microscopy, immunogold electron microscopy, and nanoscale secondary ion mass spectrometry analyses, that the LPL detected by mAb 88B8 is located within the EC glycocalyx, distant from the GPIHBP1 on the EC plasma membrane. The LPL within the glycocalyx mediates the margination of TRLs along capillaries and is active in TRL processing, resulting in the delivery of lipoprotein-derived lipids to immediately adjacent parenchymal cells. Thus, the LPL that GPIHBP1 transports into capillaries can detach and move into the EC glycocalyx, where it functions in the intravascular processing of TRLs.
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Affiliation(s)
- Wenxin Song
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA90095
| | - Anne P. Beigneux
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA90095
| | - Thomas A. Weston
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA90095
| | - Kai Chen
- Department of Chemistry, The University of Hong Kong, Hong Kong, China
- School of Molecular Sciences, The University of Western Australia, Perth6009, Australia
| | - Ye Yang
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA90095
| | - Le Phuong Nguyen
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA90095
| | - Paul Guagliardo
- Centre for Microscopy Characterisation and Analysis, The University of Western Australia, Perth6009, Australia
| | - Hyesoo Jung
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA90095
| | - Anh P. Tran
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA90095
| | - Yiping Tu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA90095
| | - Caitlyn Tran
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA90095
| | - Gabriel Birrane
- Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Boston, MA02215
| | - Kazuya Miyashita
- Department of Clinical Laboratory Medicine, Gunma University School of Medicine, Maebashi371-8511, Japan
| | - Katsuyuki Nakajima
- Department of Clinical Laboratory Medicine, Gunma University School of Medicine, Maebashi371-8511, Japan
| | - Masami Murakami
- Department of Clinical Laboratory Medicine, Gunma University School of Medicine, Maebashi371-8511, Japan
| | - Peter Tontonoz
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, CA90095
| | - Haibo Jiang
- Department of Chemistry, The University of Hong Kong, Hong Kong, China
| | - Michael Ploug
- Finsen Laboratory, Copenhagen University Hospital-Rigshospitalet, Copenhagen NDK–2200, Denmark
- Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen NDK-2200, Denmark
| | - Loren G. Fong
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA90095
| | - Stephen G. Young
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA90095
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA90095
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Hein M, Mehnert A, Freund KB, Yu DY, Balaratnasingam C. Variability in Capillary Perfusion Is Increased in Regions of Retinal Ischemia Due to Branch Retinal Vein Occlusion. Invest Ophthalmol Vis Sci 2023; 64:30. [PMID: 37856113 PMCID: PMC10615145 DOI: 10.1167/iovs.64.13.30] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 09/23/2023] [Indexed: 10/20/2023] Open
Abstract
Purpose To investigate alterations in macular perfusion variability due to branch retinal vein occlusion (BRVO) using a novel approach based on optical coherence tomography angiography (OCTA) coefficient of variation (CoV) analysis. Methods Thirteen eyes of 13 patients with macular ischemia due to BRVO were studied. Multiple consecutive en face OCTA images were acquired. Bias field correction, spatial alignment, and normalization of intensities across the images were performed followed by pixelwise computation of standard deviation divided by the mean to generate a CoV map. Region of interest-based CoV values, derived from this map, for arterioles, venules, and the microvasculature were compared between regions with macular ischemia and control areas of the same eye. Control areas were regions of the same macula that were not affected by the BRVO and had normal retinal vascular structure as seen on multimodal imaging and normal retinal vascular density measurements as quantified using OCTA. Results CoV increased by a mean value of 17.6% within the microvasculature of ischemic regions compared to the control microvasculature (P < 0.0001). CoV measurements of microvasculature were consistently greater in the ischemic area of all 13 eyes compared to control. There were no differences in CoV measurements between ischemic and control areas for arterioles (P = 0.13) and venules (P = 1.0). Conclusions Greater variability in microvasculature perfusion occurs at sites of macular ischemia due to BRVO. We report a novel way for quantifying macular perfusion variability using OCTA. This technique may have applicability for studying the pathophysiology of other retinal vascular diseases.
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Affiliation(s)
- Martin Hein
- Lions Eye Institute, Nedlands, Western Australia, Australia
- Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Australia
| | - Andrew Mehnert
- Lions Eye Institute, Nedlands, Western Australia, Australia
- Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Australia
| | - K. Bailey Freund
- Vitreous Retina Macula Consultants of New York, New York, New York, United States
- Department of Ophthalmology, New York University Grossman School of Medicine, New York, New York, United States
| | - Dao-Yi Yu
- Lions Eye Institute, Nedlands, Western Australia, Australia
- Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Australia
| | - Chandrakumar Balaratnasingam
- Lions Eye Institute, Nedlands, Western Australia, Australia
- Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Australia
- Department of Ophthalmology, Sir Charles Gairdner Hospital, Western Australia, Perth, Australia
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Li B, Leng J, Şencan-Eğilmez I, Takase H, Alfadhel MAH, Fu B, Shahidi M, Lo EH, Arai K, Sakadžić S. Differential reductions in the capillary red-blood-cell flux between retina and brain under chronic global hypoperfusion. NEUROPHOTONICS 2023; 10:035001. [PMID: 37323511 PMCID: PMC10266089 DOI: 10.1117/1.nph.10.3.035001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 04/13/2023] [Accepted: 04/26/2023] [Indexed: 06/17/2023]
Abstract
Significance It has been hypothesized that abnormal microcirculation in the retina might predict the risk of ischemic damages in the brain. Direct comparison between the retinal and the cerebral microcirculation using similar animal preparation and under similar experimental conditions would help test this hypothesis. Aim We investigated capillary red-blood-cell (RBC) flux changes under controlled conditions and bilateral-carotid-artery-stenosis (BCAS)-induced hypoperfusion, and then compared them with our previous measurements performed in the brain. Approach We measured capillary RBC flux in mouse retina with two-photon microscopy using a fluorescence-labeled RBC-passage approach. Key physiological parameters were monitored during experiments to ensure stable physiology. Results We found that under the controlled conditions, capillary RBC flux in the retina was much higher than in the brain (i.e., cerebral cortical gray matter and subcortical white matter), and that BCAS induced a much larger decrease in capillary RBC flux in the retina than in the brain. Conclusions We demonstrated a two-photon microscopy-based technique to efficiently measure capillary RBC flux in the retina. Since cerebral subcortical white matter often exhibits early pathological developments due to global hypoperfusion, our results suggest that retinal microcirculation may be utilized as an early marker of brain diseases involving global hypoperfusion.
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Affiliation(s)
- Baoqiang Li
- 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
- Harvard Medical School, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
| | - Ji Leng
- 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
| | - Ikbal Şencan-Eğilmez
- Harvard Medical School, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
| | - Hajime Takase
- Harvard Medical School, Massachusetts General Hospital, Department of Radiology, Charlestown, Massachusetts, United States
- Harvard Medical School, Massachusetts General Hospital, Department of Neurology, Charlestown, Massachusetts, United States
| | - Mohammed Ali H. Alfadhel
- Harvard Medical School, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
| | - Buyin Fu
- Harvard Medical School, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
| | - Mahnaz Shahidi
- University of Southern California, Department of Ophthalmology, Los Angeles, California, United States
| | - Eng H. Lo
- Harvard Medical School, Massachusetts General Hospital, Department of Radiology, Charlestown, Massachusetts, United States
- Harvard Medical School, Massachusetts General Hospital, Department of Neurology, Charlestown, Massachusetts, United States
| | - Ken Arai
- Harvard Medical School, Massachusetts General Hospital, Department of Radiology, Charlestown, Massachusetts, United States
- Harvard Medical School, Massachusetts General Hospital, Department of Neurology, Charlestown, Massachusetts, United States
| | - Sava Sakadžić
- Harvard Medical School, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
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Baassiri K, Nicolau DV. Investigating the Mechanism of Intravascular Bubble Formation in Designed Arrays of Vascularized Systems on a Chip. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023; 2023:1-5. [PMID: 38083489 DOI: 10.1109/embc40787.2023.10340569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
Vascular gas embolism is a rare medical condition, resulting from the existence of air or gas in the venous or arterial system. Gas embolism is associated with a wide range of circulatory, cardiovascular, and neurological complications that can lead to sudden and unexplained death. Despite the recent increase in related studies, gas embolism remains under-reported with a poor understanding of its genesis and pathophysiology. In this work, intravascular bubble formation is investigated in an array of biomimetic microscale systems, where the endogenous generation of gas bubbles is induced by variations in the surrounding pressure. Microfluidic devices, based on polydimethylsiloxane, are designed and fabricated as vascularized systems on a chip with one main channel at two different diameters (30 µm, and 40 µm), surrounded by a pressure chamber (200 µm) on each side, at a separation of 50 µm. Two blood-equivalent solutions, at 20% and 46% hematocrit concentrations were prepared from a glycerin and xanthan gum mixture to mimic the physicochemical characteristics of the blood. As the volume of injected air increased, the events related to gas embolism were occurring at shorter timespans with more significant characteristics, i.e., length and number of bubbles. Additionally, correlations were established between the input parameters, i.e., the vascular diameter and equivalent hematocrit concentration, and the output parameters, i.e., the bubble size, velocity, frequency, and nucleation sites.Clinical Relevance- The reported results constitute a reproducible observation and quantification of intravascular bubble formation induced by global pressure variations, where the emergence of bubbles exhibits different patterns depending on biological characteristics related to gender and medical history.
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Ul Banna H, Mitchell B, Chen S, Palko J. Super-Resolution Ultrasound Localization Microscopy Using High-Frequency Ultrasound to Measure Ocular Perfusion Velocity in the Rat Eye. Bioengineering (Basel) 2023; 10:689. [PMID: 37370620 PMCID: PMC10295416 DOI: 10.3390/bioengineering10060689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 05/15/2023] [Accepted: 05/24/2023] [Indexed: 06/29/2023] Open
Abstract
Imaging of the ocular vasculature can provide new insights into the pathophysiology of ocular diseases. This study proposes a novel high-frequency super-resolution ultrasound localization microscopy (SRULM) technique and evaluates its ability to measure in vivo perfusion changes in the rat eye at elevated intraocular pressure (IOP). A 38.4 MHz center frequency linear array transducer on a VisualSonics Vevo F2 imaging platform was used to collect high frame rate (1 kHz) radiofrequency data of the posterior rat eye following systemic microbubble contrast injection. Following clutter and spatiotemporal non-local means filtering, individual microbubbles were localized and tracked. The microbubble tracks were accumulated over 10,000 frames to generate vascular images quantifying perfusion velocity and direction. Experiments were performed using physiologic relevant controlled flow states for algorithm validation and subsequently performed in vivo on the rat eye at 10 mm Hg IOP increments from 10 to 60 mm Hg. The posterior vasculature of the rat eye, including the ophthalmic artery, long posterior ciliary arteries and their branches, central retinal artery and retinal arterioles and venules were successfully visualized, and velocities quantified at each IOP level. Significant reductions in arterial flow were measured as IOP was elevated. High-frequency SRULM can be used to visualize and quantify the perfusion velocity of the rat eye in both the retrobulbar and intraocular vasculature simultaneously. The ability to detect ocular perfusion changes throughout the depth of the eye may help elucidate the role ischemia has in the pathophysiology of ocular diseases such as glaucoma.
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Affiliation(s)
- Hasan Ul Banna
- Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV 26505, USA
| | - Benjamin Mitchell
- Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV 26505, USA
| | - Stephen Chen
- School of Medicine, West Virginia University, Morgantown, WV 26505, USA
| | - Joel Palko
- Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV 26505, USA
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Böhm EW, Pfeiffer N, Wagner FM, Gericke A. Methods to measure blood flow and vascular reactivity in the retina. Front Med (Lausanne) 2023; 9:1069449. [PMID: 36714119 PMCID: PMC9877427 DOI: 10.3389/fmed.2022.1069449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 12/23/2022] [Indexed: 01/14/2023] Open
Abstract
Disturbances of retinal perfusion are involved in the onset and maintenance of several ocular diseases, including diabetic retinopathy, glaucoma, and retinal vascular occlusion. Hence, knowledge on ocular vascular anatomy and function is highly relevant for basic research studies and for clinical judgment and treatment. The retinal vasculature is composed of the superficial, intermediate, and deep vascular layer. Detection of changes in blood flow and vascular diameter especially in smaller vessels is essential to understand and to analyze vascular diseases. Several methods to evaluate blood flow regulation in the retina have been described so far, but no gold standard has been established. For highly reliable assessment of retinal blood flow, exact determination of vessel diameter is necessary. Several measurement methods have already been reported in humans. But for further analysis of retinal vascular diseases, studies in laboratory animals, including genetically modified mice, are important. As for mice, the small vessel size is challenging requiring devices with high optic resolution. In this review, we recapitulate different methods for retinal blood flow and vessel diameter measurement. Moreover, studies in humans and in experimental animals are described.
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Balaratnasingam C, An D, Hein M, Yu P, Yu DY. Studies of the retinal microcirculation using human donor eyes and high-resolution clinical imaging: Insights gained to guide future research in diabetic retinopathy. Prog Retin Eye Res 2022; 94:101134. [PMID: 37154065 DOI: 10.1016/j.preteyeres.2022.101134] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 09/18/2022] [Accepted: 10/03/2022] [Indexed: 11/06/2022]
Abstract
The microcirculation plays a key role in delivering oxygen to and removing metabolic wastes from energy-intensive retinal neurons. Microvascular changes are a hallmark feature of diabetic retinopathy (DR), a major cause of irreversible vision loss globally. Early investigators have performed landmark studies characterising the pathologic manifestations of DR. Previous works have collectively informed us of the clinical stages of DR and the retinal manifestations associated with devastating vision loss. Since these reports, major advancements in histologic techniques coupled with three-dimensional image processing has facilitated a deeper understanding of the structural characteristics in the healthy and diseased retinal circulation. Furthermore, breakthroughs in high-resolution retinal imaging have facilitated clinical translation of histologic knowledge to detect and monitor progression of microcirculatory disturbances with greater precision. Isolated perfusion techniques have been applied to human donor eyes to further our understanding of the cytoarchitectural characteristics of the normal human retinal circulation as well as provide novel insights into the pathophysiology of DR. Histology has been used to validate emerging in vivo retinal imaging techniques such as optical coherence tomography angiography. This report provides an overview of our research on the human retinal microcirculation in the context of the current ophthalmic literature. We commence by proposing a standardised histologic lexicon for characterising the human retinal microcirculation and subsequently discuss the pathophysiologic mechanisms underlying key manifestations of DR, with a focus on microaneurysms and retinal ischaemia. The advantages and limitations of current retinal imaging modalities as determined using histologic validation are also presented. We conclude with an overview of the implications of our research and provide a perspective on future directions in DR research.
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Affiliation(s)
- Chandrakumar Balaratnasingam
- Lions Eye Institute, Nedlands, Western Australia, Australia; Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Australia; Department of Ophthalmology, Sir Charles Gairdner Hospital, Western Australia, Australia.
| | - Dong An
- Lions Eye Institute, Nedlands, Western Australia, Australia; Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Australia
| | - Martin Hein
- Lions Eye Institute, Nedlands, Western Australia, Australia; Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Australia
| | - Paula Yu
- Lions Eye Institute, Nedlands, Western Australia, Australia; Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Australia
| | - Dao-Yi Yu
- Lions Eye Institute, Nedlands, Western Australia, Australia; Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Australia
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Mac KD, Qureshi MM, Na M, Chang S, Eom TJ, Je HS, Kim YR, Kwon HS, Chung E. Fast volumetric imaging with line-scan confocal microscopy by electrically tunable lens at resonant frequency. OPTICS EXPRESS 2022; 30:19152-19164. [PMID: 36221700 PMCID: PMC9363030 DOI: 10.1364/oe.450745] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 04/25/2022] [Accepted: 04/26/2022] [Indexed: 05/20/2023]
Abstract
In microscopic imaging of biological tissues, particularly real-time visualization of neuronal activities, rapid acquisition of volumetric images poses a prominent challenge. Typically, two-dimensional (2D) microscopy can be devised into an imaging system with 3D capability using any varifocal lens. Despite the conceptual simplicity, such an upgrade yet requires additional, complicated device components and usually suffers from a reduced acquisition rate, which is critical to properly document rapid neurophysiological dynamics. In this study, we implemented an electrically tunable lens (ETL) in the line-scan confocal microscopy (LSCM), enabling the volumetric acquisition at the rate of 20 frames per second with a maximum volume of interest of 315 × 315 × 80 µm3. The axial extent of point-spread-function (PSF) was 17.6 ± 1.6 µm and 90.4 ± 2.1 µm with the ETL operating in either stationary or resonant mode, respectively, revealing significant depth axial penetration by the resonant mode ETL microscopy. We further demonstrated the utilities of the ETL system by volume imaging of both cleared mouse brain ex vivo samples and in vivo brains. The current study showed a successful application of resonant ETL for constructing a high-performance 3D axially scanning LSCM (asLSCM) system. Such advances in rapid volumetric imaging would significantly enhance our understanding of various dynamic biological processes.
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Affiliation(s)
- Khuong Duy Mac
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea
| | | | - Myeongsu Na
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, 03080 Seoul, Republic of Korea
| | - Sunghoe Chang
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, 03080 Seoul, Republic of Korea
- Neuroscience Research Institute, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, 03080 Seoul, Republic of Korea
| | - Tae Joong Eom
- Department of Cogno-Mechatronics Engineering, Pusan National University, Busan, 46241, Republic of Korea
- Engineering Research Center (ERC) for Color-modulated Extra-sensory Perception Technology, Pusan National University, Busan, 46241, Republic of Korea
| | - Hyunsoo Shawn Je
- Signature Program in Neuroscience and Behavioural Disorders, Duke-National University of Singapore (NUS) Medical School, 8 College Road 169857, Singapore
- Advanced Bioimaging Center, Academia, Ngee Ann Kongsi Discovery Tower Level 10, 20 College Road, 169855, Singapore
| | - Young Ro Kim
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA
- Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Hyuk-Sang Kwon
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea
| | - Euiheon Chung
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea
- AI Graduate School, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea
- Research Center for Photon Science Technology, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea
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11
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Chaigneau E, Charpak S. Measurement of Blood Velocity With Laser Scanning Microscopy: Modeling and Comparison of Line-Scan Image-Processing Algorithms. Front Physiol 2022; 13:848002. [PMID: 35464098 PMCID: PMC9022085 DOI: 10.3389/fphys.2022.848002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 02/22/2022] [Indexed: 11/13/2022] Open
Abstract
Laser scanning microscopy is widely used to measure blood hemodynamics with line-scans in physiological and pathological vessels. With scans of broken lines, i.e., lines made of several segments with different orientations, it also allows simultaneous monitoring of vessel diameter dynamics or the activity of specific cells. Analysis of red blood cell (RBC) velocity from line-scans requires specific image-processing algorithms, as angle measurements, Line-Scanning Particle Image Velocimetry (LSPIV) or Fourier transformation of line-scan images. The conditions under which these image-processing algorithms give accurate measurements have not been fully characterized although the accuracy of measurements vary according to specific experimental parameters: the vessel type, the RBC velocity, the scanning parameters, and the image signal to noise ratio. Here, we developed mathematical models for the three previously mentioned line-scan image-processing algorithms. Our models predict the experimental conditions in which RBC velocity measurements are accurate. We illustrate the case of different vessel types and give the parameter space available for each of them. Last, we developed a software generating artificial line-scan images and used it to validate our models.
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Affiliation(s)
- Emmanuelle Chaigneau
- Institut de la Vision, INSERM U968, Paris, France
- Institut de la Vision, CNRS UMR 7210, Paris, France
- Institut de la Vision, Sorbonne Université, Paris, France
- *Correspondence: Emmanuelle Chaigneau,
| | - Serge Charpak
- Institut de la Vision, INSERM U968, Paris, France
- Institut de la Vision, CNRS UMR 7210, Paris, France
- Institut de la Vision, Sorbonne Université, Paris, France
- Serge Charpak,
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12
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Dholakia KY, Guevara-Torres A, Feng G, Power D, Schallek J. In Vivo Capillary Structure and Blood Cell Flux in the Normal and Diabetic Mouse Eye. Invest Ophthalmol Vis Sci 2022; 63:18. [PMID: 35138346 PMCID: PMC8842443 DOI: 10.1167/iovs.63.2.18] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Purpose To characterize the early structural and functional changes in the retinal microvasculature in response to hyperglycemia in the Ins2Akita mouse. Methods A custom phase-contrast adaptive optics scanning light ophthalmoscope was used to image retinal capillaries of 9 Ins2Akita positive (hyperglycemic) and 9 Ins2Akita negative (euglycemic) mice from postnatal weeks 5 to 18. A 15 kHz point scan was used to image capillaries and measure red blood cell flux at biweekly intervals; measurements were performed manually. Retinal thickness and fundus photos were captured monthly using a commercial scanning laser ophthalmoscope/optical coherence tomography. Retinal thickness was calculated using a custom algorithm. Blood glucose and weight were tracked throughout the duration of the study. Results Elevated blood glucose (>250 mg/dL) was observed at 4 to 5 weeks of age in Ins2Akita mice and remained elevated throughout the study, whereas euglycemic littermates maintained normal glucose levels. There was no significant difference in red blood cell flux, capillary anatomy, lumen diameter, or occurrence of stalled capillaries between hyperglycemic and euglycemic mice between postnatal weeks 5 and 18. Hyperglycemic mice had a thinner retina than euglycemic littermates (p < 0.001), but retinal thickness did not change with duration of hyperglycemia despite glucose levels that were more than twice times normal. Conclusions In early stages of hyperglycemia, retinal microvasculature structure (lumen diameter, capillary anatomy) and function (red blood cell flux, capillary perfusion) were not impaired despite 3 months of chronically elevated blood glucose. These findings suggest that hyperglycemia alone for 3 months does not alter capillary structure or function in profoundly hyperglycemic mice.
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Affiliation(s)
- Kosha Y Dholakia
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, United States.,Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Andres Guevara-Torres
- Center for Visual Science, University of Rochester, Rochester, New York, United States.,The Institute of Optics, University of Rochester, Rochester, New York, United States
| | - Guanping Feng
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, United States.,Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Derek Power
- Center for Visual Science, University of Rochester, Rochester, New York, United States.,Flaum Eye Institute, University of Rochester, Rochester, New York, United States
| | - Jesse Schallek
- Center for Visual Science, University of Rochester, Rochester, New York, United States.,Flaum Eye Institute, University of Rochester, Rochester, New York, United States.,Department of Neuroscience, University of Rochester, Rochester, New York, United States
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13
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Kumar S, Jiang D, Sun B, Seeley KV, Engle JW, Sia Z, He X, Neelamegham S, Cai W, Lovell JF. Labeling of Erythrocytes by Porphyrin-Phospholipid. ADVANCED NANOBIOMED RESEARCH 2020; 1. [PMID: 34212160 DOI: 10.1002/anbr.202000013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
A method is developed for membrane labeling of erythrocytes with porphyrin-phospholipid (PoP). To generate a concentrated PoP solution for labeling human red blood cells (RBCs), various surfactants and solvents are screened to identify conditions that avoid hemolysis, while minimizing non-specific PoP co-precipitation with RBCs in the pellet during centrifugation washes. Cholate, Tween 80 and Tween 40 are identified as useful surfactants for this purpose. When labeled RBCs are mixed with unlabeled ones, substantial non-specific PoP exchange is observed. Egg-yolk lecithin is included in a washing buffer to remove loosely bound PoP and reduce PoP exchange with unlabeled erythrocytes, based on flow cytometry and photodynamic hemolysis assays. Murine RBCs that are labeled with 64Cu-chelated PoP displayed altered biodistribution with longer blood circulation relative to directly administered 64Cu-chelated PoP.
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Affiliation(s)
- Sunanda Kumar
- Department of Biomedical Engineering, State University of New York at Buffalo, NY 14260, USA
| | - Dawei Jiang
- Department of Materials Science and Engineering, Department of Radiology, Department of Medical Physics, and University of Wisconsin Carbone Cancer Center, University of Wisconsin, Madison, Madison, Wisconsin 53705, United States
| | - Boyang Sun
- Department of Biomedical Engineering, State University of New York at Buffalo, NY 14260, USA
| | - Kaelyn V Seeley
- Department of Materials Science and Engineering, Department of Radiology, Department of Medical Physics, and University of Wisconsin Carbone Cancer Center, University of Wisconsin, Madison, Madison, Wisconsin 53705, United States
| | - Jonathan W Engle
- Department of Materials Science and Engineering, Department of Radiology, Department of Medical Physics, and University of Wisconsin Carbone Cancer Center, University of Wisconsin, Madison, Madison, Wisconsin 53705, United States
| | - Zachary Sia
- Department of Biomedical Engineering, State University of New York at Buffalo, NY 14260, USA
| | - Xuedan He
- Department of Biomedical Engineering, State University of New York at Buffalo, NY 14260, USA
| | - Sriram Neelamegham
- Department of Chemical Engineering, State University of New York at Buffalo, NY 14260, USA
| | - Weibo Cai
- Department of Materials Science and Engineering, Department of Radiology, Department of Medical Physics, and University of Wisconsin Carbone Cancer Center, University of Wisconsin, Madison, Madison, Wisconsin 53705, United States
| | - Jonathan F Lovell
- Department of Biomedical Engineering, State University of New York at Buffalo, NY 14260, USA
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14
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Zhang YS, Lee HE, Kwan CC, Schwartz GW, Fawzi AA. Caffeine Delays Retinal Neurovascular Coupling during Dark to Light Adaptation in Healthy Eyes Revealed by Optical Coherence Tomography Angiography. Invest Ophthalmol Vis Sci 2020; 61:37. [PMID: 32340030 PMCID: PMC7401906 DOI: 10.1167/iovs.61.4.37] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Purpose The purpose of this study was to investigate the acute effects of caffeine on retinal hemodynamics during dark to light adaptation using optical coherence tomography angiography (OCTA). Methods Thirteen healthy individuals (13 eyes) underwent OCTA imaging after dark adaptation and at repeated intervals during the transition to ambient light in two imaging sessions: control and after ingesting 200 mg of caffeine. We analyzed the parafoveal vessel density (VD) and adjusted flow index (AFI) of the superficial capillary plexus (SCP), middle capillary plexus (MCP), and deep capillary plexus (DCP), as well as the vessel length density (VLD) of the SCP. After adjusting for age, refractive error, and scan quality, we compared parameters between control and caffeine conditions. Results In the dark, MCP VD decreased significantly after caffeine (−2.63 ± 1.28%). During the transition to light, initially, DCP VD increased (12.55 ± 2.52%), whereas SCP VD decreased (−2.09 ± 0.91%) significantly with caffeine compared to control. By 15 minutes in light, DCP VD reversed and was significantly decreased (−5.45 ± 2.62%), whereas MCP VD increased (4.65 ± 1.74%). There were no differences in AFI or VLD. Conclusions We show that, overall, caffeine causes a trend of delayed vascular response in all three macular capillary plexuses in response to ambient light. Whereas the MCP is constricted in the dark, during the transition from dark to light, there is initially delay followed by prolonged constriction of the DCP and constriction followed by slow dilation of the SCP. We posit that these delayed vascular responses may present potential risk of capillary ischemia.
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15
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Fu X, Sompol P, Brandon JA, Norris CM, Wilkop T, Johnson LA, Richards CI. In Vivo Single-Molecule Detection of Nanoparticles for Multiphoton Fluorescence Correlation Spectroscopy to Quantify Cerebral Blood Flow. NANO LETTERS 2020; 20:6135-6141. [PMID: 32628854 PMCID: PMC8405275 DOI: 10.1021/acs.nanolett.0c02280] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We present the application of multiphoton in vivo fluorescence correlation spectroscopy (FCS) of fluorescent nanoparticles for the measurement of cerebral blood flow with excellent spatial and temporal resolution. Through the detection of single nanoparticles within the complex vessel architecture of a live mouse, this new approach enables the quantification of nanoparticle dynamics occurring within the vasculature along with simultaneous measurements of blood flow properties in the brain. In addition to providing high resolution blood flow measurements, this approach enables real-time quantification of nanoparticle concentration, degradation, and transport. This method is capable of quantifying flow rates at each pixel with submicron resolution to enable monitoring of dynamic changes in flow rates in response to changes in the animal's physiological condition. Scanning the excitation beam using FCS provides pixel by pixel mapping of flow rates with subvessel resolution across capillaries 300 μm deep in the brains of mice.
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Affiliation(s)
- Xu Fu
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Pradoldej Sompol
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky 40536, United States
| | - Jason A Brandon
- Department of Physiology, University of Kentucky, Lexington, Kentucky 40536, United States
| | - Christopher M Norris
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky 40536, United States
| | - Thomas Wilkop
- Light Microscopy Core, University of Kentucky, Lexington, Kentucky 40536, United States
| | - Lance A Johnson
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky 40536, United States
- Department of Physiology, University of Kentucky, Lexington, Kentucky 40536, United States
| | - Christopher I Richards
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
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16
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Imaging volumetric dynamics at high speed in mouse and zebrafish brain with confocal light field microscopy. Nat Biotechnol 2020; 39:74-83. [PMID: 32778840 DOI: 10.1038/s41587-020-0628-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Accepted: 07/08/2020] [Indexed: 12/12/2022]
Abstract
A detailed understanding of the function of neural networks and how they are supported by a dynamic vascular system requires fast three-dimensional imaging in thick tissues. Here we present confocal light field microscopy, a method that enables fast volumetric imaging in the brain at depths of hundreds of micrometers. It uses a generalized confocal detection scheme that selectively collects fluorescent signals from the in-focus volume and provides optical sectioning capability to improve imaging resolution and sensitivity in thick tissues. We demonstrate recording of whole-brain calcium transients in freely swimming zebrafish larvae and observe behaviorally correlated activities in single neurons during prey capture. Furthermore, in the mouse brain, we detect neural activities at depths of up to 370 μm and track blood cells at 70 Hz over a volume of diameter 800 μm × thickness 150 μm and depth of up to 600 μm.
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17
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Invernizzi A, Pellegrini M, Cornish E, Yi Chong Teo K, Cereda M, Chabblani J. Imaging the Choroid: From Indocyanine Green Angiography to Optical Coherence Tomography Angiography. Asia Pac J Ophthalmol (Phila) 2020; 9:335-348. [PMID: 32739938 DOI: 10.1097/apo.0000000000000307] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The choroid is the vascular structure nourishing the retinal pigment epithelium and the outer retina and it plays a key role in the homeostasis of the eye both under physiological and pathological conditions. In the last 20 years we have moved from "guessing" what was happening beyond the retinal pigment epithelium to actually visualize structural and functional changes of the choroid in vivo noninvasively. In this review we describe the state of the art of choroidal imaging, focusing on the multiple techniques available in the clinical and research setting including indocyanine green angiography, labeled-cells angiographies, optical coherence tomography (OCT), enhanced depth imaging, swept source OCT, and OCT angiography. In the first section of the article, we describe their main applications and the basic principles to interpret the imaging results. Increasing evidence suggests that the choroid is much more involved than we used to think in many pathological conditions from uveitis to intraocular tumors, from vascular diseases to age-related macular degeneration. All clinicians should hence know which is the most appropriate imaging investigation to explore the choroid in the disease they are dealing with and how to interpret the results. For this reason the second section of this review summarizes the best imaging approach and the most common findings visible on choroidal imaging in different diseases of the eye.
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Affiliation(s)
- Alessandro Invernizzi
- Eye Clinic, Department of Biomedical and Clinical Science "Luigi Sacco," Luigi Sacco Hospital, University of Milan, Milan, Italy
- The University of Sydney, Save Sight Institute, Discipline of Ophthalmology, Sydney Medical School, Sydney, New South Wales, Australia
| | - Marco Pellegrini
- Eye Clinic, Department of Biomedical and Clinical Science "Luigi Sacco," Luigi Sacco Hospital, University of Milan, Milan, Italy
| | - Elisa Cornish
- The University of Sydney, Save Sight Institute, Discipline of Ophthalmology, Sydney Medical School, Sydney, New South Wales, Australia
| | - Kelvin Yi Chong Teo
- The University of Sydney, Save Sight Institute, Discipline of Ophthalmology, Sydney Medical School, Sydney, New South Wales, Australia
- Singapore National Eye Center, Singapore
- Singapore Eye Research Institute, Singapore
| | - Matteo Cereda
- Eye Clinic, Department of Biomedical and Clinical Science "Luigi Sacco," Luigi Sacco Hospital, University of Milan, Milan, Italy
| | - Jay Chabblani
- Department of Ophthalmology, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
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18
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Cognart HA, Viovy JL, Villard C. Fluid shear stress coupled with narrow constrictions induce cell type-dependent morphological and molecular changes in SK-BR-3 and MDA-MB-231 cells. Sci Rep 2020; 10:6386. [PMID: 32286431 PMCID: PMC7156718 DOI: 10.1038/s41598-020-63316-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 03/26/2020] [Indexed: 12/31/2022] Open
Abstract
Cancer mortality mainly arises from metastases, due to cells that escape from a primary tumor, circulate in the blood as circulating tumor cells (CTCs), permeate across blood vessels and nest in distant organs. It is still unclear how CTCs overcome the harsh conditions of fluid shear stress and mechanical constraints within the microcirculation. Here, a minimal model of the blood microcirculation was established through the fabrication of microfluidic channels comprising constrictions. Metastatic breast cancer cells of epithelial-like and mesenchymal-like phenotypes were flowed into the microfluidic device. These cells were visualized during circulation and analyzed for their dynamical behavior, revealing long-lived plastic deformations and significant differences in biomechanics between cell types. γ-H2AX staining of cells retrieved post-circulation showed significant increase of DNA damage response in epithelial-like SK-BR-3 cells, while gene expression analysis of key regulators of epithelial-to-mesenchymal transition revealed significant changes upon circulation. This work thus documents first results of the changes at the cellular, subcellular and molecular scales induced by the two main mechanical stimuli arising from circulatory conditions, and suggest a significant role of this still elusive step of the metastatic cascade in cancer cells heterogeneity and aggressiveness.
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Affiliation(s)
- Hamizah Ahmad Cognart
- Institut Curie and Institut Pierre Gilles de Gennes, CNRS, UMR168, Paris, France.,Université PSL, Paris, France
| | - Jean-Louis Viovy
- Institut Curie and Institut Pierre Gilles de Gennes, CNRS, UMR168, Paris, France.,Université PSL, Paris, France
| | - Catherine Villard
- Institut Curie and Institut Pierre Gilles de Gennes, CNRS, UMR168, Paris, France. .,Université PSL, Paris, France.
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19
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Al-Essa MK, Melzer S, Tarnok A, Hadidi KA, El-Khateeb M. Fast RBC loading by fluorescent antibodies and nuclei staining dye and their potential bioanalytical applications. ACTA ACUST UNITED AC 2019; 73:95-105. [PMID: 28792915 DOI: 10.1515/znc-2017-0054] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 07/10/2017] [Indexed: 12/18/2022]
Abstract
This study was designed to load different antibodies (Abs) and a fluorescent dye onto the red blood cell (RBC) surface. We have used fluorescein isothiocyanate (FITC)-conjugate anti-human Ab, CD22-PE (B-cell marker-phycoerythrin Ab), and 4',6-diamidino-2-phenylindole (DAPI) for insertion over the RBC surface. In a first step, conjugation experiments were performed: in dimethyl sulfoxide (DMSO), RBCs were conserved and modified by succinic anhydride to create an additional -COOH group, and then activated with 3-(3-dimethylaminopropyl)carbodiimide-N-hydroxysuccinimide (EDC-NHS) in 2-(N-morpholino) ethanesulfonic acid hydrate buffer for insertion of labeled Abs or DAPI. In a second step, fluorescence signals were evaluated by microscopy and the mean fluorescence intensities of cell lysates were measured by spectrofluorometry. The results showed clear evidence for adsorption of FITC- and PE-labeled Abs to activated conserved RBCs. DAPI was adsorbed well also to DMSO-conserved RBCs without the need for an activation step. The DMSO conservation step was enough to create reactive RBCs for insertion of specific Abs and fluorescent dyes. The additional modification by succinic anhydride and activation with EDC-NHS resulted in two- to seven-fold increase in fluorescence signals, indicating a much higher RBC loading capacity. These Ab- and fluorescent dye-functionalized RBCs have potentially high application in developing new biomedical diagnostic and in vitro assay techniques.
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Affiliation(s)
- Mohamed K Al-Essa
- Department of Physiology and Biochemistry, Faculty of Medicine, The University of Jordan, Amman 11942, Jordan, Phone: +962 6 5355000-23477, Fax: +962 6 5300820
| | - Susanne Melzer
- Clinical Trial Centre Leipzig, University of Leipzig, Leipzig, Germany
| | - Attila Tarnok
- Translational Center for Regenerative Medicine (TRM)/Sächsischer Inkubator für Klinische Translation (SIKT), Leipzig, Germany
| | - Kamal A Hadidi
- Department of Pathology, Faculty of Medicine, The University of Jordan, Amman, Jordan
| | - Mohammed El-Khateeb
- Department of Pathology, Faculty of Medicine, The University of Jordan, Amman, Jordan
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20
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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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21
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Joseph A, Guevara-Torres A, Schallek J. Imaging single-cell blood flow in the smallest to largest vessels in the living retina. eLife 2019; 8:45077. [PMID: 31084705 PMCID: PMC6516827 DOI: 10.7554/elife.45077] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 04/15/2019] [Indexed: 01/15/2023] Open
Abstract
Tissue light scatter limits the visualization of the microvascular network deep inside the living mammal. The transparency of the mammalian eye provides a noninvasive view of the microvessels of the retina, a part of the central nervous system. Despite its clarity, imperfections in the optics of the eye blur microscopic retinal capillaries, and single blood cells flowing within. This limits early evaluation of microvascular diseases that originate in capillaries. To break this barrier, we use 15 kHz adaptive optics imaging to noninvasively measure single-cell blood flow, in one of the most widely used research animals: the C57BL/6J mouse. Measured flow ranged four orders of magnitude (0.0002-1.55 µL min-1) across the full spectrum of retinal vessel diameters (3.2-45.8 µm), without requiring surgery or contrast dye. Here, we describe the ultrafast imaging, analysis pipeline and automated measurement of millions of blood cell speeds.
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Affiliation(s)
- Aby Joseph
- Institute of Optics, University of Rochester, New York, United States.,Center for Visual Science, University of Rochester, New York, United States
| | - Andres Guevara-Torres
- Institute of Optics, University of Rochester, New York, United States.,Center for Visual Science, University of Rochester, New York, United States
| | - Jesse Schallek
- Center for Visual Science, University of Rochester, New York, United States.,Flaum Eye Institute, University of Rochester, New York, United States.,Department of Neuroscience, University of Rochester, New York, United States
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22
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Pi S, Camino A, Wei X, Simonett J, Cepurna W, Huang D, Morrison JC, Jia Y. Rodent retinal circulation organization and oxygen metabolism revealed by visible-light optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2018; 9:5851-5862. [PMID: 30460167 PMCID: PMC6238898 DOI: 10.1364/boe.9.005851] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 10/22/2018] [Accepted: 10/24/2018] [Indexed: 05/06/2023]
Abstract
Visible light optical coherence tomography (vis-OCT) is an emerging label-free and high-resolution 3-dimensional imaging technique that can provide retinal oximetry, angiography, and flowmetry in one modality. In this paper, we studied the organization of the arterial and venous retinal circulation in rats using vis-OCT. Arterioles were found predominantly in the superficial vascular plexus whereas veins tended to drain capillaries from the deep capillary plexus. After that, we determined the oxygen metabolic rate supported by retinal microcirculation by combining retinal vessel oxygen saturation and blood flow measurements. The ability to visualize and monitor retinal circulation organization and oxygen metabolism by vis-OCT may provide new opportunities for understanding the pathology of ocular diseases.
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Affiliation(s)
- Shaohua Pi
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Acner Camino
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Xiang Wei
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Joseph Simonett
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - William Cepurna
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - David Huang
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - John C. Morrison
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Yali Jia
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
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23
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Gu B, Wang X, Twa MD, Tam J, Girkin CA, Zhang Y. Noninvasive in vivo characterization of erythrocyte motion in human retinal capillaries using high-speed adaptive optics near-confocal imaging. BIOMEDICAL OPTICS EXPRESS 2018; 9:3653-3677. [PMID: 30338146 PMCID: PMC6191635 DOI: 10.1364/boe.9.003653] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 07/02/2018] [Accepted: 07/02/2018] [Indexed: 05/18/2023]
Abstract
The flow of erythrocytes in parafoveal capillaries was imaged in the living human eye with an adaptive optics near-confocal ophthalmoscope at a frame rate of 800 Hz with a low coherence near-infrared (NIR) light source. Spatiotemporal traces of the erythrocyte movement were extracted from consecutive images. Erythrocyte velocity was measured using custom software based on the Radon transform. The impact of imaging speed on velocity measurement was estimated using images of frame rates of 200, 400, and 800 Hz. The NIR light allowed for long imaging periods without visually stimulating the retina and disturbing the natural rheological state. High speed near-confocal imaging enabled direct and accurate measurement of erythrocyte velocity, and revealed a distinctively cardiac-dependent pulsatile velocity waveform of the erythrocyte flow in retinal capillaries, disclosed the impact of the leukocytes on erythrocyte motion, and provided new metrics for precise assessment of erythrocyte movement. The approach may facilitate new investigations on the pathophysiology of retinal microcirculation with applications for ocular and systemic diseases.
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Affiliation(s)
- Boyu Gu
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294, USA
| | - Xiaolin Wang
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294, USA
| | - Michael D. Twa
- Department of Optometry and Vision Science, School of Optometry, University of Alabama at Birmingham, 1716 University Boulevard, Birmingham, AL 35294, USA
| | - Johnny Tam
- National Eye Institute, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA
| | - Christopher A. Girkin
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294, USA
| | - Yuhua Zhang
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294, USA
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24
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Gericke A, Goloborodko E, Pfeiffer N, Manicam C. Preparation Steps for Measurement of Reactivity in Mouse Retinal Arterioles Ex Vivo. J Vis Exp 2018. [PMID: 29806833 DOI: 10.3791/56199] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Vascular insufficiency and alterations in normal retinal perfusion are among the major factors for the pathogenesis of various sight-threatening ocular diseases, such as diabetic retinopathy, hypertensive retinopathy, and possibly glaucoma. Therefore, retinal microvascular preparations are pivotal tools for physiological and pharmacological studies to delineate the underlying pathophysiological mechanisms and to design therapies for the diseases. Despite the wide use of mouse models in ophthalmic research, studies on retinal vascular reactivity are scarce in this species. A major reason for this discrepancy is the challenging isolation procedures owing to the small size of these retinal blood vessels, which is ~ ≤ 30 µm in luminal diameter. To circumvent the problem of direct isolation of these retinal microvessels for functional studies, we established an isolation and preparation technique that enables ex vivo studies of mouse retinal vasoactivity under near-physiological conditions. Although the present experimental preparations will specifically refer to the mouse retinal arterioles, this methodology can readily be employed to microvessels from rats.
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Affiliation(s)
- Adrian Gericke
- Department of Ophthalmology, University Medical Center of the Johannes Gutenberg University Mainz;
| | - Evgeny Goloborodko
- Department of Ophthalmology, University Medical Center of the Johannes Gutenberg University Mainz
| | - Norbert Pfeiffer
- Department of Ophthalmology, University Medical Center of the Johannes Gutenberg University Mainz
| | - Caroline Manicam
- Department of Ophthalmology, University Medical Center of the Johannes Gutenberg University Mainz
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25
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Tan B, MacLellan B, Mason E, Bizheva K. Structural, functional and blood perfusion changes in the rat retina associated with elevated intraocular pressure, measured simultaneously with a combined OCT+ERG system. PLoS One 2018; 13:e0193592. [PMID: 29509807 PMCID: PMC5839563 DOI: 10.1371/journal.pone.0193592] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 02/14/2018] [Indexed: 02/07/2023] Open
Abstract
Acute elevation of intraocular pressure (IOP) to ischemic and non-ischemic levels can cause temporary or permanent changes in the retinal morphology, function and blood flow/blood perfusion. Previously, such changes in the retina were assessed separately with different methods in clinical studies and animal models. In this study, we used a combined OCT+ ERG system in combination with Doppler OCT and OCT angiography (OCTA) imaging protocols, in order to evaluate simultaneously and correlate changes in the retinal morphology, the retinal functional response to visual stimulation, and the retinal blood flow/blood perfusion, associated with IOP elevation to ischemic and non-ischemic levels in rats. Results from this study suggest that the inner retina responds faster to IOP elevation to levels greater than 30 mmHg with significant reduction of the total retinal blood flow (TRBF), decrease of the capillaries’ perfusion and reduction of the ON bipolar cells contribution to the ERG traces. Furthermore, this study showed that ischemic levels of IOP elevation cause an additional significant decrease in the ERG photoreceptor response in the posterior retina. Thirty minutes after IOP normalization, retinal morphology, blood flow and blood perfusion recovered to baseline values, while retinal function did not recover completely.
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Affiliation(s)
- Bingyao Tan
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
| | - Benjamin MacLellan
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
| | - Erik Mason
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
| | - Kostadinka Bizheva
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
- Department of System Design Engineering, University of Waterloo, Waterloo, Ontario, Canada
- * E-mail:
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26
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Agrawal R, Balne PK, Tun SBB, Sia Wey Y, Khandelwal N, Barathi VA. Fluorescent Dye Labeling of Erythrocytes and Leukocytes for Studying the Flow Dynamics in Mouse Retinal Circulation. J Vis Exp 2017. [PMID: 28715402 DOI: 10.3791/55495] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The retinal and choroidal blood flow dynamics may provide insight into the pathophysiology and sequelae of various ocular diseases, such as glaucoma, diabetic retinopathy, age-related macular degeneration (AMD) and other ocular inflammatory conditions. It may also help to monitor the therapeutic responses in the eye. The proper labeling of the blood cells, coupled with live-cell imaging of the labeled cells, allows for the investigation of the flow dynamics in the retinal and choroidal circulation. Here, we describe the standardized protocols of 1.5% indocyanine green (ICG) and 1% sodium fluorescein labeling of mice erythrocytes and leukocytes, respectively. Scanning laser ophthalmoscopy (SLO) was applied to visualize the labeled cells in the retinal circulation of C57BL/6J mice (wild type). Both methods demonstrated distinct fluorescently labeled cells in the mouse retinal circulation. These labeling methods can have wider applications in various ocular disease models.
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Affiliation(s)
- Rupesh Agrawal
- National Healthcare Group Eye Institute, Tan Tock Seng Hospital; Singapore Eye Research Institute (SERI), Singapore National Eye Center; School of Material Science and Engineering, Nanyang Technological University;
| | | | - Sai Bo Bo Tun
- Singapore Eye Research Institute (SERI), Singapore National Eye Center
| | - Yeo Sia Wey
- Singapore Eye Research Institute (SERI), Singapore National Eye Center
| | - Neha Khandelwal
- National Healthcare Group Eye Institute, Tan Tock Seng Hospital
| | - Veluchamy A Barathi
- Singapore Eye Research Institute (SERI), Singapore National Eye Center; Department of Ophthalmology, Yong Loo Lin School of Medicine, National University Health Systems, National University of Singapore; Ophthalmology Academic Clinical Research Program, DUKE-NUS Graduate Medical School;
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27
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Srienc AI, Biesecker KR, Shimoda AM, Kur J, Newman EA. Ischemia-induced spreading depolarization in the retina. J Cereb Blood Flow Metab 2016; 36:1579-91. [PMID: 27389181 PMCID: PMC5012528 DOI: 10.1177/0271678x16657836] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 05/17/2016] [Accepted: 06/07/2016] [Indexed: 02/04/2023]
Abstract
Cortical spreading depolarization is a metabolically costly phenomenon that affects the brain in both health and disease. Following severe stroke, subarachnoid hemorrhage, or traumatic brain injury, cortical spreading depolarization exacerbates tissue damage and enlarges infarct volumes. It is not known, however, whether spreading depolarization also occurs in the retina in vivo. We report now that spreading depolarization episodes are generated in the in vivo rat retina following retinal vessel occlusion produced by photothrombosis. The properties of retinal spreading depolarization are similar to those of cortical spreading depolarization. Retinal spreading depolarization waves propagate at a velocity of 3.0 ± 0.1 mm/min and are associated with a negative shift in direct current potential, a transient cessation of neuronal spiking, arteriole constriction, and a decrease in tissue O2 tension. The frequency of retinal spreading depolarization generation in vivo is reduced by administration of the NMDA antagonist MK-801 and the 5-HT(1D) agonist sumatriptan. Branch retinal vein occlusion is a leading cause of vision loss from vascular disease. Our results suggest that retinal spreading depolarization could contribute to retinal damage in acute retinal ischemia and demonstrate that pharmacological agents can reduce retinal spreading depolarization frequency after retinal vessel occlusion. Blocking retinal spreading depolarization generation may represent a therapeutic strategy for preserving vision in branch retinal vein occlusion patients.
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Affiliation(s)
- Anja I Srienc
- Graduate Program in Neuroscience, University of Minnesota, MN, USA Medical Scientist Training Program, University of Minnesota, MN, USA
| | - Kyle R Biesecker
- Graduate Program in Neuroscience, University of Minnesota, MN, USA
| | | | - Joanna Kur
- Department of Neuroscience, University of Minnesota, MN, USA
| | - Eric A Newman
- Department of Neuroscience, University of Minnesota, MN, USA
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28
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Son T, Wang B, Thapa D, Lu Y, Chen Y, Cao D, Yao X. Optical coherence tomography angiography of stimulus evoked hemodynamic responses in individual retinal layers. BIOMEDICAL OPTICS EXPRESS 2016; 7:3151-62. [PMID: 27570706 PMCID: PMC4986822 DOI: 10.1364/boe.7.003151] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 06/08/2016] [Accepted: 06/10/2016] [Indexed: 05/05/2023]
Abstract
Blood flow changes are highly related to neural activities in the retina. It has been reported that neural activity increases when flickering light stimulation of the retina is used. It is known that blood flow changes with flickering light stimulation can be altered in patients with vascular disease and that measurement of flicker-induced vasodilatation is an easily applied tool for monitoring functional microvascular alterations. However, details of distortions in retinal neurovascular coupling associated with major eye diseases are not well understood due to the limitation of existing techniques. In this study, flickering light stimulation was applied to mouse retinas to investigate stimulus evoked hemodynamic responses in individual retinal layers. A spectral domain optical coherence tomography (OCT) angiography imaging system was developed to provide dynamic mapping of hemodynamic responses in the ganglion cell layer, inner plexiform layer, outer plexiform layer and choroid layer before, during and after flickering light stimulation. Experimental results showed hemodynamic responses with different magnitudes and time courses in individual retinal layers. We anticipate that the dynamic OCT angiography of stimulus evoked hemodynamic responses can greatly foster the study of neurovascular coupling mechanisms in the retina, promising new biomarkers for retinal disease detection and diagnosis.
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Affiliation(s)
- Taeyoon Son
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Benquan Wang
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Damber Thapa
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Yiming Lu
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Yanjun Chen
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Dingcai Cao
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Xincheng Yao
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA
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