Measurement of Retinal Blood Flow Using Fluorescently Labeled Red Blood Cells

Kornfield, Tess E.; Newman, Eric A.

doi:10.1523/eneuro.0005-15.2015

Cited by 38 publications

(49 citation statements)

References 81 publications

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“…The optical opacity of the brain and scattering in its tissue requires investigation of its microvasculature to need thinned–skull preparations and fluorescent labelling of either plasma or RBCs for measurement of both velocity and lumen diameter (Drew et al, 2009; Drew, Shih, & Kleinfeld, 2011; Kim et al, 2012; Kleinfeld et al, 1998; Nishimura, Schaffer, Friedman, Lyden, & Kleinfeld, 2007; Schaffer et al, 2006; Shih et al, 2012). It is also worth mentioning important studies in the rat retina which have achieved measurement of blood flow in a large spectrum of vessel sizes/orders, using fluorescently labelled red blood cells (Kornfield & Newman, 2014, 2015). While all of the above techniques have made important advances in our understanding of microcirculation in neural tissues, the use of exogenous blood contrast agents raises the concern of maintenance of natural blood perfusion, especially at the capillary level.…”

Section: Discussionmentioning

confidence: 99%

Imaging Single–Cell Blood Flow in the Smallest to Largest Vessels in the Living Retina

Joseph

Guevara–Torres

Schallek

2019

Preprint

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Impact Statement: Using a specialized camera that corrects for eye blur, millions of single blood cells are 9 imaged and their speed measured, as they travel through the largest-to-smallest vessels of the retina. 10 Abstract: Tissue light scatter limits the visualization of the microvascular network deep inside the living 11 mammal. The transparency of the mammalian eye provides a noninvasive view of the microvessels of the retina, a 12 part of the central nervous system. Despite its clarity, imperfections in the optics of the eye blur microscopic 13 retinal capillaries, and single blood cells flowing within. This limits early evaluation of microvascular diseases 14 that originate in capillaries. To break this barrier, we use adaptive optics to noninvasively measure single-cell 15 blood flow, in one of the most widely used research animals: the C57BL/6J mouse. Flow ranged four orders of 16 magnitude (0.0002-1.55 µL min -1 ) across the full spectrum of retinal vessel diameters (3.2-45.8 µm), without 17 requiring surgery or contrast dye. Here we describe the data collection approach using adaptive optics and provide 18 an analysis pipeline that can measure millions of blood cell speeds automatically. 19 93 noninvasively in the smallest to largest vessels of the mouse retinal circulation (lumen diameters: 3.2-45.8 µm); 94 without requiring exogenous contrast agents to facilitate measurement. Measured flow rate per vessel ranged four 95 orders of magnitude (0.0002-1.55 µL min -1 ) across the complete retinal vascular tree, from the largest vessel near 96 the optic disk to the smallest capillary. In addition to aiding basic science investigation, the non-invasive 97 approach provides a comprehensive array of bioreporters of microvascular perfusion, including: cell velocity, 98 lumen diameter, flow rate, single-cell flux in capillaries, pulsatile and laminar flow, and indices of intrinsic 99 temporal and spatial modulations in flow. To our knowledge, we provide the first measurement of cross-sectional 100 velocity profile and the first absolute measurement of pulsatile velocity in the mouse retina. We also provide the 101 4 first measures of mean (and pulsatile) velocity and flow rate in medium and small vessels (capillaries) of the 102 mouse retina. We found that there is a heterogenous distribution of velocity, flux and other hemodynamic 103 parameters in vessels of varying generation/size, showing that diameter alone is a poor predictor of 104 microcirculation hemodynamics in the central nervous system. Through the innovations presented in this work, 105 imaging the complete and intact perfusion system of the mammalian retina bridges an important gap in studying 106 perfusion dynamics in deep microvascular beds within the living body. And due to the central nervous system 107 origin of the retina, this method provides a powerful way to noninvasively study microvascular integrity and 108 kinetics in a portion of the living brain. 109 Methods 110 Animals 111 19 normal C57BL/6J mice (The Jackson Laboratory stock 000664...

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Section: Discussionmentioning

confidence: 99%

Imaging Single–Cell Blood Flow in the Smallest to Largest Vessels in the Living Retina

Joseph

Guevara–Torres

Schallek

2019

Preprint

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“…The axial and lateral resolutions can be estimated as 2 0.44 λ / Δλ ⋅ and 0.61 λ / NA ⋅ , respectively, where λ is the central wavelength, Δλ is the bandwidth of the SLD and NA is the numerical aperture in this system. The blood vessel diameter in the mouse retina is in the range of 30.0 ± 6.7 µm for arterioles and 46.5 ± 16.5 µm for venules [44]. Because the thickness of the mouse retina is about 200 ~250 µm, the depth of field (DOF) of the OCT system was designed at 300 µm and was calculated using…”

Section: Animal Preparationmentioning

confidence: 99%

Optical coherence tomography angiography of stimulus evoked hemodynamic responses in individual retinal layers

Son

Wang

Thapa

et al. 2016

Biomed. Opt. Express

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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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“…Red blood cell (RBC) flux through arterioles was measured as previously described. 28 Briefly, blood was withdrawn from the animal at the beginning of an experiment and RBCs were isolated and incubated for 5 min in the fluorescent lipophilic dye DiD (carbocyanide 1,1 0 -dioctadecyl-3,3,3 0 ,3 0 -tetramethylindodicarbocyanide,4-chlorobenzenesulfonate salt solid; Invitrogen; #D-7757). Cells were washed in buffer to remove unbound dye and reinjected into the animal.…”

Section: Red Blood Cell Fluxmentioning

confidence: 99%

Ischemia-induced spreading depolarization in the retina

Srienc

Biesecker

Shimoda

et al. 2016

J Cereb Blood Flow Metab

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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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Measurement of Retinal Blood Flow Using Fluorescently Labeled Red Blood Cells

Abstract: Accurately measuring blood flow in the retina is an important challenge, as blood flow reflects the health of retinal tissue and is disrupted in many diseases. Existing techniques for measuring blood flow are limited due to the complex assumptions and calculations required.

Cited by 38 publications

References 81 publications

Imaging Single–Cell Blood Flow in the Smallest to Largest Vessels in the Living Retina

Imaging Single–Cell Blood Flow in the Smallest to Largest Vessels in the Living Retina

Optical coherence tomography angiography of stimulus evoked hemodynamic responses in individual retinal layers

Ischemia-induced spreading depolarization in the retina

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