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Madekurozwa M, Reina-Torres E, Overby DR, van Batenburg-Sherwood J. Measurement of postmortem outflow facility using iPerfusion. Exp Eye Res 2022; 220:109103. [PMID: 35525299 DOI: 10.1016/j.exer.2022.109103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 04/24/2022] [Accepted: 04/28/2022] [Indexed: 11/04/2022]
Abstract
The key risk factor for glaucoma is elevation of intraocular pressure (IOP) and alleviating it is the only effective therapeutic approach to inhibit further vision loss. IOP is regulated by the flow of aqueous humour across resistive tissues, and a reduction in outflow facility C, is responsible for the IOP elevation in glaucoma. Measurement of C is therefore important when investigating the pathophysiology of glaucoma and testing candidate treatments for lowering IOP. Due to similar anatomy and response to pharmacological treatments, mouse eyes are a common model of human aqueous humour dynamics. The ex vivo preparation, in which an enucleated mouse eye is mounted in a temperature controlled bath and cannulated, has been well characterised and is widely used. The postmortem in situ model, in which the eyes are perfused within the cadaver, has received relatively little attention. In this study, we investigate the postmortem in situ model using the iPerfusion system, with a particular focus on i) the presence or absence of pressure-independent flow, ii) the effect of evaporation on measured flow rates and iii) the magnitude and pressure dependence of outflow facility and how these properties are affected by postmortem changes. Measurements immediately after cannulation and following multi-pressure facility measurement demonstrated negligible pressure-independent flow in postmortem eyes, in contrast to assumptions made in previous studies. Using a humidity chamber, we investigated whether the humidity of the surrounding air would influence measured flow rates. We found that at room levels of humidity, evaporation of saline droplets on the eye resulted in artefactual flow rates with a magnitude comparable to outflow, which were eliminated by a high relative humidity (>85%) environment. Average postmortem outflow facility was ∼4 nl/min/mmHg, similar to values observed ex vivo, irrespective of whether a postmortem delay was introduced prior to cannulation. The intra-animal variability of measured outflow facility values was also reduced relative to previous ex vivo data. The pressure-dependence of outflow facility was reduced in the postmortem relative to ex vivo model, and practically eliminated when eyes were cannulated >40 min after euthanisation. Overall, our results indicate that the moderately increased technical complexity associated with postmortem perfusion provides reduced variability and reduced pressure-dependence in outflow facility, when experimental conditions are properly controlled.
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Affiliation(s)
| | | | - Darryl R Overby
- Dept. of Bioengineering, Imperial College London, London, SW7 2AZ, UK.
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McDowell CM, Kizhatil K, Elliott MH, Overby DR, van Batenburg-Sherwood J, Millar JC, Kuehn MH, Zode G, Acott TS, Anderson MG, Bhattacharya SK, Bertrand JA, Borras T, Bovenkamp DE, Cheng L, Danias J, De Ieso ML, Du Y, Faralli JA, Fuchshofer R, Ganapathy PS, Gong H, Herberg S, Hernandez H, Humphries P, John SWM, Kaufman PL, Keller KE, Kelley MJ, Kelly RA, Krizaj D, Kumar A, Leonard BC, Lieberman RL, Liton P, Liu Y, Liu KC, Lopez NN, Mao W, Mavlyutov T, McDonnell F, McLellan GJ, Mzyk P, Nartey A, Pasquale LR, Patel GC, Pattabiraman PP, Peters DM, Raghunathan V, Rao PV, Rayana N, Raychaudhuri U, Reina-Torres E, Ren R, Rhee D, Chowdhury UR, Samples JR, Samples EG, Sharif N, Schuman JS, Sheffield VC, Stevenson CH, Soundararajan A, Subramanian P, Sugali CK, Sun Y, Toris CB, Torrejon KY, Vahabikashi A, Vranka JA, Wang T, Willoughby CE, Xin C, Yun H, Zhang HF, Fautsch MP, Tamm ER, Clark AF, Ethier CR, Stamer WD. Consensus Recommendation for Mouse Models of Ocular Hypertension to Study Aqueous Humor Outflow and Its Mechanisms. Invest Ophthalmol Vis Sci 2022; 63:12. [PMID: 35129590 PMCID: PMC8842499 DOI: 10.1167/iovs.63.2.12] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 12/08/2021] [Indexed: 01/07/2023] Open
Abstract
Due to their similarities in anatomy, physiology, and pharmacology to humans, mice are a valuable model system to study the generation and mechanisms modulating conventional outflow resistance and thus intraocular pressure. In addition, mouse models are critical for understanding the complex nature of conventional outflow homeostasis and dysfunction that results in ocular hypertension. In this review, we describe a set of minimum acceptable standards for developing, characterizing, and utilizing mouse models of open-angle ocular hypertension. We expect that this set of standard practices will increase scientific rigor when using mouse models and will better enable researchers to replicate and build upon previous findings.
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Affiliation(s)
- Colleen M. McDowell
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | | | - Michael H. Elliott
- University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Darryl R. Overby
- Department of Bioengineering, Imperial College London, United Kingdom
| | | | - J. Cameron Millar
- Department of Pharmacology & Neuroscience, and North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Markus H. Kuehn
- Department of Ophthalmology and Visual Sciences and Institute for Vision Research, The University of Iowa; Center for the Prevention and Treatment of Visual Loss, Veterans Affairs Medical Center, Iowa City, Iowa, United States
| | - Gulab Zode
- Department of Pharmacology & Neuroscience, and North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Ted S. Acott
- Ophthalmology and Biochemistry and Molecular Biology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Michael G. Anderson
- Department of Molecular Physiology and Biophysics and Department of Ophthalmology and Visual Sciences, The University of Iowa; Center for the Prevention and Treatment of Visual Loss, Veterans Affairs Medical Center, Iowa City, Iowa, United States
| | | | - Jacques A. Bertrand
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Terete Borras
- University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
| | | | - Lin Cheng
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
| | - John Danias
- SUNY Downstate Health Sciences University, Brooklyn, New York, United States
| | - Michael Lucio De Ieso
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, North Carolina, United States
| | - Yiqin Du
- Department of Ophthalmology, University of Pittsburgh, Pennsylvania, United States
| | - Jennifer A. Faralli
- Department of Pathology and Laboratory Medicine, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Rudolf Fuchshofer
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
| | - Preethi S. Ganapathy
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, New York, United States
| | - Haiyan Gong
- Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Samuel Herberg
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, New York, United States
| | | | - Peter Humphries
- Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Simon W. M. John
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - Paul L. Kaufman
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Kate E. Keller
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Mary J. Kelley
- Department of Ophthalmology and Department of Integrative Biosciences, Oregon Health & Science University, Portland, Oregon, United States
| | - Ruth A. Kelly
- Ocular Genetics Unit, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - David Krizaj
- Department of Ophthalmology, University of Utah School of Medicine, Salt Lake City, Utah, United States
| | - Ajay Kumar
- Department of Ophthalmology, University of Pittsburgh, Pennsylvania, United States
| | - Brian C. Leonard
- Department of Surgical and Radiological Sciences, University of California, Davis, Davis, California, United States
| | - Raquel L. Lieberman
- Department of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, United States
| | - Paloma Liton
- Department of Ophthalmology and Department of Pathology, Duke University, Durham, North Carolina, United States
| | - Yutao Liu
- Department of Cellular Biology and Anatomy, James & Jean Culver Vision Discovery Institute, Augusta University, Augusta, Georgia, United States
| | - Katy C. Liu
- Duke Eye Center, Duke Health, Durham, North Carolina, United States
| | - Navita N. Lopez
- Department of Neurobiology, University of Utah, Salt Lake City, Utah, United States
| | - Weiming Mao
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Timur Mavlyutov
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Fiona McDonnell
- Duke Eye Center, Duke Health, Durham, North Carolina, United States
| | - Gillian J. McLellan
- Department of Surgical Sciences and Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Philip Mzyk
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Andrews Nartey
- College of Optometry, University of Houston, Houston, Texas, United States
| | - Louis R. Pasquale
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, New York, United States
| | - Gaurang C. Patel
- Ophthalmology Research, Regeneron Pharmaceuticals, Tarreytown, New York, United States
| | | | - Donna M. Peters
- Department of Pathology and Laboratory Medicine, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | | | - Ponugoti Vasantha Rao
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States
| | - Naga Rayana
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Urmimala Raychaudhuri
- Department of Neurobiology, University of California, Irvine, Irvine, California, United States
| | - Ester Reina-Torres
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Ruiyi Ren
- Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Douglas Rhee
- Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Uttio Roy Chowdhury
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - John R. Samples
- Washington State University, Floyd Elson College of Medicine, Spokane, Washington, United States
| | | | - Najam Sharif
- Santen Inc., Emeryville, California, United States
| | - Joel S. Schuman
- Department of Ophthalmology and Department of Physiology and Neuroscience, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, United States; Departments of Biomedical Engineering and Electrical and Computer Engineering, New York University Tandon School of Engineering, Brooklyn, New York, United States; Center for Neural Science, College of Arts and Science, New York University, New York, New York, United States
| | - Val C. Sheffield
- Department of Pediatrics and Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States
| | - Cooper H. Stevenson
- Department of Pharmacology & Neuroscience, and North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Avinash Soundararajan
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | | | - Chenna Kesavulu Sugali
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Yang Sun
- Veterans Affairs Palo Alto Health Care System, Stanford University, Palo Alto, California, United States
| | - Carol B. Toris
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States; Department of Ophthalmology and Vision Sciences, The Ohio State University, Columbus, Ohio, United States
| | | | - Amir Vahabikashi
- Cell and Developmental Biology Department, Northwestern University, Chicago, Illinois, United States
| | - Janice A. Vranka
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Ting Wang
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Colin E. Willoughby
- Genomic Medicine, Biomedical Sciences Research Institute, Ulster University, Coleraine, Northern Ireland, United Kingdom
| | - Chen Xin
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Hongmin Yun
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Hao F. Zhang
- Biomedical Engineering Department, Northwestern University, Evanston, Illinois, United States
| | - Michael P. Fautsch
- Biomedical Engineering Department, Northwestern University, Evanston, Illinois, United States
| | | | - Abbot F. Clark
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - C. Ross Ethier
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology; Emory University School of Medicine, Emory University, Atlanta, Georgia, United States
| | - W. Daniel Stamer
- Duke Ophthalmology, Duke University, Durham, North Carolina, United States
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Madekurozwa M, Stamer WD, Reina-Torres E, Sherwood JM, Overby DR. The ocular pulse decreases aqueous humor outflow resistance by stimulating nitric oxide production. Am J Physiol Cell Physiol 2021; 320:C652-C665. [PMID: 33439773 PMCID: PMC8260357 DOI: 10.1152/ajpcell.00473.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 12/21/2020] [Accepted: 01/12/2021] [Indexed: 11/22/2022]
Abstract
Intraocular pressure (IOP) is not static, but rather oscillates by 2-3 mmHg because of cardiac pulsations in ocular blood volume known as the ocular pulse. The ocular pulse induces pulsatile shear stress in Schlemm's canal (SC). We hypothesize that the ocular pulse modulates outflow facility by stimulating shear-induced nitric oxide (NO) production by SC cells. We confirmed that living mice exhibit an ocular pulse with a peak-to-peak (pk-pk) amplitude of 0.5 mmHg under anesthesia. Using iPerfusion, we measured outflow facility (flow/pressure) during alternating periods of steady or pulsatile IOP in both eyes of 16 cadaveric C57BL/6J mice (13-14 weeks). Eyes were retained in situ, with an applied mean pressure of 8 mmHg and 1.0 mmHg pk-pk pressure amplitude at 10 Hz to mimic the murine heart rate. One eye of each cadaver was perfused with 100 µM L-NAME to inhibit NO synthase, whereas the contralateral eye was perfused with vehicle. During the pulsatile period in the vehicle-treated eye, outflow facility increased by 16 [12, 20] % (P < 0.001) relative to the facility measured during the preceding and subsequent steady periods. This effect was partly inhibited by L-NAME, where pressure pulsations increased outflow facility by 8% [4, 12] (P < 0.001). Thus, the ocular pulse causes an immediate increase in outflow facility in mice, with roughly one-half of the facility increase attributable to NO production. These studies reveal a dynamic component to outflow function that responds instantly to the ocular pulse and may be important for outflow regulation and IOP homeostasis.
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Affiliation(s)
- Michael Madekurozwa
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina
| | - Ester Reina-Torres
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Joseph M Sherwood
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, United Kingdom
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Abstract
Purpose Conventional wisdom posits that aqueous humor leaves the eye by passive bulk flow without involving energy-dependent processes. However, recent studies have shown that active processes, such as cell contractility, contribute to outflow regulation. Here, we examine whether inhibiting cellular metabolism affects outflow facility in mice. Methods We measured outflow facility in paired enucleated eyes from C57BL/6J mice using iPerfusion. We had three Experimental Sets: ES1, perfused at 35°C versus 22°C; ES2, perfused with metabolic inhibitors versus vehicle at 35°C; and ES3, perfused at 35°C versus 22°C in the presence of metabolic inhibitors. Inhibitors targeted glycolysis and oxidative phosphorylation (2-deoxy-D-glucose, 3PO and sodium azide). We also measured adenosine triphosphate (ATP) levels in separate murine anterior segments treated like ES1 and ES2. Results Reducing temperature decreased facility by 63% [38%, 78%] (mean [95% confidence interval (CI)], n = 10 pairs; P = 0.002) in ES1 after correcting for changes in viscosity. Metabolic inhibitors reduced facility by 21% [9%, 31%] (n = 9, P = 0.006) in ES2. In the presence of inhibitors, temperature reduction decreased facility by 44% [29%, 56%] (n = 8, P < 0.001) in ES3. Metabolic inhibitors reduced anterior segment adenosine triphosphate (ATP) levels by 90% [83%, 97%] (n = 5, P<<0.001), but reducing temperature did not affect ATP. Conclusions Inhibiting cellular metabolism decreases outflow facility within minutes. This implies that outflow is not entirely passive, but depends partly on energy-dependent cellular processes, at least in mice. This study also suggests that there is a yet unidentified mechanism, which is strongly temperature-dependent but metabolism-independent, that is necessary for nearly half of normal outflow function in mice.
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Affiliation(s)
- Ester Reina-Torres
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | | | - Joseph M Sherwood
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, United Kingdom
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Reina-Torres E, De Ieso ML, Pasquale LR, Madekurozwa M, van Batenburg-Sherwood J, Overby DR, Stamer WD. The vital role for nitric oxide in intraocular pressure homeostasis. Prog Retin Eye Res 2020; 83:100922. [PMID: 33253900 DOI: 10.1016/j.preteyeres.2020.100922] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 11/13/2020] [Accepted: 11/23/2020] [Indexed: 02/07/2023]
Abstract
Catalyzed by endothelial nitric oxide (NO) synthase (eNOS) activity, NO is a gaseous signaling molecule maintaining endothelial and cardiovascular homeostasis. Principally, NO regulates the contractility of vascular smooth muscle cells and permeability of endothelial cells in response to either biochemical or biomechanical cues. In the conventional outflow pathway of the eye, the smooth muscle-like trabecular meshwork (TM) cells and Schlemm's canal (SC) endothelium control aqueous humor outflow resistance, and therefore intraocular pressure (IOP). The mechanisms by which outflow resistance is regulated are complicated, but NO appears to be a key player as enhancement or inhibition of NO signaling dramatically affects outflow function; and polymorphisms in NOS3, the gene that encodes eNOS modifies the relation between various environmental exposures and glaucoma. Based upon a comprehensive review of past foundational studies, we present a model whereby NO controls a feedback signaling loop in the conventional outflow pathway that is sensitive to changes in IOP and its oscillations. Thus, upon IOP elevation, the outflow pathway tissues distend, and the SC lumen narrows resulting in increased SC endothelial shear stress and stretch. In response, SC cells upregulate the production of NO, relaxing neighboring TM cells and increasing permeability of SC's inner wall. These IOP-dependent changes in the outflow pathway tissues reduce the resistance to aqueous humor drainage and lower IOP, which, in turn, diminishes the biomechanical signaling on SC. Similar to cardiovascular pathogenesis, dysregulation of the eNOS/NO system leads to dysfunctional outflow regulation and ocular hypertension, eventually resulting in primary open-angle glaucoma.
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Affiliation(s)
| | | | - Louis R Pasquale
- Eye and Vision Research Institute of New York Eye and Ear Infirmary at Mount Sinai, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | | | | | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, UK.
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, NC, USA.
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Cassidy PS, Kelly RA, Reina-Torres E, Sherwood JM, Humphries MM, Kiang AS, Farrar GJ, O'Brien C, Campbell M, Stamer WD, Overby DR, Humphries P, O'Callaghan J. siRNA targeting Schlemm's canal endothelial tight junctions enhances outflow facility and reduces IOP in a steroid-induced OHT rodent model. Mol Ther Methods Clin Dev 2020; 20:86-94. [PMID: 33376757 PMCID: PMC7749298 DOI: 10.1016/j.omtm.2020.10.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 10/27/2020] [Indexed: 11/28/2022]
Abstract
Systemic or localized application of glucocorticoids (GCs) can lead to iatrogenic ocular hypertension, which is a leading cause of secondary open-angle glaucoma and visual impairment. Previous work has shown that dexamethasone increases zonula occludens-1 (ZO-1) protein expression in trabecular meshwork (TM) cells, and that an antisense oligonucleotide inhibitor of ZO-1 can abolish the dexamethasone-induced increase in trans-endothelial flow resistance in cultured Schlemm’s canal (SC) endothelial and TM cells. We have previously shown that intracameral inoculation of small interfering RNA (siRNA) targeting SC endothelial cell tight junction components, ZO-1 and tricellulin, increases aqueous humor outflow facility ex vivo in normotensive mice by reversibly opening SC endothelial paracellular pores. In this study, we show that targeted siRNA downregulation of these SC endothelial tight junctions reduces intraocular pressure (IOP) in vivo, with a concomitant increase in conventional outflow facility in a well-characterized chronic steroid-induced mouse model of ocular hypertension, thus representing a potential focused clinical application for this therapy in a sight-threatening scenario.
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Affiliation(s)
- Paul S Cassidy
- Ocular Genetics Unit, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Ruth A Kelly
- Ocular Genetics Unit, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Ester Reina-Torres
- Ocular Genetics Unit, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland.,Department of Bioengineering, Imperial College London, London, UK
| | | | - Marian M Humphries
- Ocular Genetics Unit, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Anna-Sophia Kiang
- Ocular Genetics Unit, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - G Jane Farrar
- Ocular Genetics Unit, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Colm O'Brien
- Department of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland
| | - Matthew Campbell
- Neurovascular Research Laboratory, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, NC, USA
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, UK
| | - Pete Humphries
- Ocular Genetics Unit, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Jeffrey O'Callaghan
- Ocular Genetics Unit, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland.,Neurovascular Research Laboratory, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
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Reina-Torres E, Bertrand JA, O'Callaghan J, Sherwood JM, Humphries P, Overby DR. Reduced humidity experienced by mice in vivo coincides with reduced outflow facility measured ex vivo. Exp Eye Res 2019; 186:107745. [PMID: 31351057 DOI: 10.1016/j.exer.2019.107745] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 07/05/2019] [Accepted: 07/23/2019] [Indexed: 11/16/2022]
Abstract
Mice are routinely used to study aqueous humour dynamics. However, physical factors such as temperature and hydration affect outflow facility in enucleated eyes. This retrospective study examined whether differences in temperature and relative humidity experienced by living mice within their housing environment in vivo coincide with differences in outflow facility measured ex vivo. Facility data and environmental records were collected for one enucleated eye from 116 mice (C57BL/6J males, 9-15 weeks old) at two institutions. Outflow facility was reduced when relative humidity was below the lower limit of 45% recommended by the UK Code of Practice, but there was no detectable effect of temperature on outflow facility. Even when accounting for effects of humidity, there were differences in outflow facility measured between institutions and between individual researchers at the same institution. These data indicate that humidity, as well as additional environmental factors experienced by living mice within their housing environment, may significantly affect outflow facility measured ex vivo.
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Affiliation(s)
- Ester Reina-Torres
- Department of Bioengineering, Imperial College London, London, United Kingdom; Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, Ireland
| | - Jacques A Bertrand
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Jeffrey O'Callaghan
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, Ireland
| | - Joseph M Sherwood
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Peter Humphries
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, Ireland
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, United Kingdom.
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Madekurozwa M, Reina-Torres E, Overby DR, Sherwood JM. Direct measurement of pressure-independent aqueous humour flow using iPerfusion. Exp Eye Res 2017; 162:129-138. [PMID: 28720436 PMCID: PMC5587799 DOI: 10.1016/j.exer.2017.07.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 05/16/2017] [Accepted: 07/14/2017] [Indexed: 10/19/2022]
Abstract
Reduction of intraocular pressure is the sole therapeutic target for glaucoma. Intraocular pressure is determined by the dynamics of aqueous humour secretion and outflow, which comprise several pressure-dependent and pressure-independent mechanisms. Accurately quantifying the components of aqueous humour dynamics is essential in understanding the pathology of glaucoma and the development of new treatments. To better characterise aqueous humour dynamics, we propose a method to directly measure pressure-independent aqueous humour flow. Using the iPerfusion system, we directly measure the flow into the eye when the pressure drop across the pressure-dependent pathways is eliminated. Using this approach we address i) the magnitude of pressure-independent flow in ex vivo eyes, ii) whether we can accurately measure an artificially imposed pressure-independent flow, and iii) whether the presence of a pressure-independent flow affects our ability to measure outflow facility. These studies are conducted in mice, which are a common animal model for aqueous humour dynamics. In eyes perfused with a single cannula, the average pressure-independent flow was 1 [-3, 5] nl/min (mean [95% confidence interval]) (N = 6). Paired ex vivo eyes were then cannulated with two needles, connecting the eye to both iPerfusion and a syringe pump, which was used to impose a known pressure-independent flow of 120 nl/min into the experimental eye only. The measured pressure-independent flow was then 121 [117, 125] nl/min (N = 7), indicating that the method could measure pressure-independent flow with high accuracy. Finally, we showed that the artificially imposed pressure-independent flow did not affect our ability to measure facility, provided that the pressure-dependence of facility and the true pressure-independent flow were accounted for. The present study provides a robust method for measurement of pressure-independent flow, and demonstrates the importance of accurately quantifying this parameter when investigating pressure-dependent flow or outflow facility.
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Affiliation(s)
| | | | - Darryl R Overby
- Dept. of Bioengineering, Imperial College London, London SW7 2AZ, UK.
| | - Joseph M Sherwood
- Dept. of Bioengineering, Imperial College London, London SW7 2AZ, UK
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Reina-Torres E, Wen JC, Liu KC, Li G, Sherwood JM, Chang JYH, Challa P, Flügel-Koch CM, Stamer WD, Allingham RR, Overby DR. VEGF as a Paracrine Regulator of Conventional Outflow Facility. Invest Ophthalmol Vis Sci 2017; 58:1899-1908. [PMID: 28358962 PMCID: PMC5374885 DOI: 10.1167/iovs.16-20779] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Purpose Vascular endothelial growth factor (VEGF) regulates microvascular endothelial permeability, and the permeability of Schlemm's canal (SC) endothelium influences conventional aqueous humor outflow. We hypothesize that VEGF signaling regulates outflow facility. Methods We measured outflow facility (C) in enucleated mouse eyes perfused with VEGF-A164a, VEGF-A165b, VEGF-D, or inhibitors to VEGF receptor 2 (VEGFR-2). We monitored VEGF-A secretion from human trabecular meshwork (TM) cells by ELISA after 24 hours of static culture or cyclic stretch. We used immunofluorescence microscopy to localize VEGF-A protein within the TM of mice. Results VEGF-A164a increased C in enucleated mouse eyes. Cyclic stretch increased VEGF-A secretion by human TM cells, which corresponded to VEGF-A localization in the TM of mice. Blockade of VEGFR-2 decreased C, using either of the inhibitors SU5416 or Ki8751 or the inactive splice variant VEGF-A165b. VEGF-D increased C, which could be blocked by Ki8751. Conclusions VEGF is a paracrine regulator of conventional outflow facility that is secreted by TM cells in response to mechanical stress. VEGF affects facility via VEGFR-2 likely at the level of SC endothelium. Disruption of VEGF signaling in the TM may explain why anti-VEGF therapy is associated with decreased outflow facility and sustained ocular hypertension.
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Affiliation(s)
- Ester Reina-Torres
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Joanne C Wen
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Katy C Liu
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Guorong Li
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Joseph M Sherwood
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Jason Y H Chang
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Pratap Challa
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Cassandra M Flügel-Koch
- Department of Anatomy II, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen, Germany
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - R Rand Allingham
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, United Kingdom
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Wen JC, Reina-Torres E, Sherwood JM, Challa P, Liu KC, Li G, Chang JYH, Cousins SW, Schuman SG, Mettu PS, Stamer WD, Overby DR, Allingham RR. Intravitreal Anti-VEGF Injections Reduce Aqueous Outflow Facility in Patients With Neovascular Age-Related Macular Degeneration. Invest Ophthalmol Vis Sci 2017; 58:1893-1898. [PMID: 28358961 PMCID: PMC6022414 DOI: 10.1167/iovs.16-20786] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Purpose We assess the effect of intravitreal anti-VEGF injections on tonographic outflow facility. Methods Patients with age-related macular degeneration who had received unilateral intravitreal anti-VEGF injections were recruited into two groups, those with ≤10 and those with ≥20 total anti-VEGF injections. Intraocular pressure and tonographic outflow facility of injected and uninjected fellow eyes were measured and compared between groups. Risk factors for development of reduced outflow facility also were assessed. Results Outflow facility was 12% lower in the injected eyes of patients who received ≥20 anti-VEGF injections, compared to contralateral uninjected eyes (P = 0.02). In contrast, there was no facility reduction for patients with ≤10 anti-VEGF injections (P = 0.4). In patients with ocular hypertension in the uninjected eye (IOP > 21 mm Hg, n = 5), the outflow facility of injected eyes was on average 46% lower (P = 0.01) than in the uninjected fellow eyes. This was significantly greater than the difference observed in patients with IOP ≤ 21 mm Hg in the uninjected eye (P = 2 × 10−4). In patients with ocular hypertension in the injected eye (n = 6) the differences in facility and IOP between contralateral eyes were significantly greater than in patients with IOP ≤ 21 mm Hg in the injected eye (P = 2 × 10−4 and P = 7 × 10−4, respectively). Conclusions Chronic anti-VEGF injections significantly reduce outflow facility in patients with AMD. The greatest facility reduction is observed in patients with baseline ocular hypertension. Ophthalmologists who administer anti-VEGF injections should be aware of these findings and monitor patients closely for changes in IOP or evidence of glaucoma, especially in those with pre-existing ocular hypertension.
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Affiliation(s)
- Joanne C Wen
- Department of Ophthalmology, University of Washington, Seattle, Washington, United States 2Department of Ophthalmology, Duke University Eye Center, Durham, North Carolina, United States
| | - Ester Reina-Torres
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Joseph M Sherwood
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Pratap Challa
- Department of Ophthalmology, Duke University Eye Center, Durham, North Carolina, United States
| | - Katy C Liu
- Department of Ophthalmology, Duke University Eye Center, Durham, North Carolina, United States
| | - Guorong Li
- Department of Ophthalmology, Duke University Eye Center, Durham, North Carolina, United States
| | - Jason Y H Chang
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Scott W Cousins
- Department of Ophthalmology, Duke University Eye Center, Durham, North Carolina, United States
| | - Stefanie G Schuman
- Department of Ophthalmology, Duke University Eye Center, Durham, North Carolina, United States
| | - Priyatham S Mettu
- Department of Ophthalmology, Duke University Eye Center, Durham, North Carolina, United States
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University Eye Center, Durham, North Carolina, United States
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - R Rand Allingham
- Department of Ophthalmology, Duke University Eye Center, Durham, North Carolina, United States
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O'Callaghan J, Crosbie DE, Cassidy PS, Sherwood JM, Flügel-Koch C, Lütjen-Drecoll E, Humphries MM, Reina-Torres E, Wallace D, Kiang AS, Campbell M, Stamer WD, Overby DR, O'Brien C, Tam LCS, Humphries P. Therapeutic potential of AAV-mediated MMP-3 secretion from corneal endothelium in treating glaucoma. Hum Mol Genet 2017; 26:1230-1246. [PMID: 28158775 PMCID: PMC5390678 DOI: 10.1093/hmg/ddx028] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 01/18/2017] [Indexed: 11/13/2022] Open
Abstract
Intraocular pressure (IOP) is maintained as a result of the balance between production of aqueous humour (AH) by the ciliary processes and hydrodynamic resistance to its outflow through the conventional outflow pathway comprising the trabecular meshwork (TM) and Schlemm's canal (SC). Elevated IOP, which can be caused by increased resistance to AH outflow, is a major risk factor for open-angle glaucoma. Matrix metalloproteinases (MMPs) contribute to conventional aqueous outflow homeostasis in their capacity to remodel extracellular matrices, which has a direct impact on aqueous outflow resistance and IOP. We observed decreased MMP-3 activity in human glaucomatous AH compared to age-matched normotensive control AH. Treatment with glaucomatous AH resulted in significantly increased transendothelial resistance of SC endothelial and TM cell monolayers and reduced monolayer permeability when compared to control AH, or supplemented treatment with exogenous MMP-3.Intracameral inoculation of AAV-2/9 containing a CMV-driven MMP-3 gene (AAV-MMP-3) into wild type mice resulted in efficient transduction of corneal endothelium and an increase in aqueous concentration and activity of MMP-3. Most importantly, AAV-mediated expression of MMP-3 increased outflow facility and decreased IOP, and controlled expression using an inducible promoter activated by topical administration of doxycycline achieved the same effect. Ultrastructural analysis of MMP-3 treated matrices by transmission electron microscopy revealed remodelling and degradation of core extracellular matrix components. These results indicate that periodic induction, via use of an eye drop, of AAV-mediated secretion of MMP-3 into AH could have therapeutic potential for those cases of glaucoma that are sub-optimally responsive to conventional pressure-reducing medications.
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Affiliation(s)
- Jeffrey O'Callaghan
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
| | - Darragh E Crosbie
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
| | - Paul S Cassidy
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
| | - Joseph M Sherwood
- Department of Bioengineering, Imperial College London, London, SW7 2BX, UK
| | - Cassandra Flügel-Koch
- Department of Anatomy II, University of Erlangen-Nürnberg, D-91054 Erlangen, Germany
| | - Elke Lütjen-Drecoll
- Department of Anatomy II, University of Erlangen-Nürnberg, D-91054 Erlangen, Germany
| | - Marian M Humphries
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
| | - Ester Reina-Torres
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
| | - Deborah Wallace
- Clinical Research Centre, UCD School of Medicine and Medical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Anna-Sophia Kiang
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
| | - Matthew Campbell
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
| | - W Daniel Stamer
- Departments of Ophthalmology and Biomedical Engineering, Duke University, Durham, NC, USA
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, SW7 2BX, UK
| | - Colm O'Brien
- Department of Ophthalmology, Mater Misericordiae University Hospital, Dublin, D7, Ireland
| | - Lawrence C S Tam
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
| | - Peter Humphries
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
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12
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Tam LCS, Reina-Torres E, Sherwood JM, Cassidy PS, Crosbie DE, Lütjen-Drecoll E, Flügel-Koch C, Perkumas K, Humphries MM, Kiang AS, O'Callaghan J, Callanan JJ, Read AT, Ethier CR, O'Brien C, Lawrence M, Campbell M, Stamer WD, Overby DR, Humphries P. Enhancement of Outflow Facility in the Murine Eye by Targeting Selected Tight-Junctions of Schlemm's Canal Endothelia. Sci Rep 2017; 7:40717. [PMID: 28091584 PMCID: PMC5238500 DOI: 10.1038/srep40717] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 12/09/2016] [Indexed: 11/12/2022] Open
Abstract
The juxtacanalicular connective tissue of the trabecular meshwork together with inner wall endothelium of Schlemm’s canal (SC) provide the bulk of resistance to aqueous outflow from the anterior chamber. Endothelial cells lining SC elaborate tight junctions (TJs), down-regulation of which may widen paracellular spaces between cells, allowing greater fluid outflow. We observed significant increase in paracellular permeability following siRNA-mediated suppression of TJ transcripts, claudin-11, zonula-occludens-1 (ZO-1) and tricellulin in human SC endothelial monolayers. In mice claudin-11 was not detected, but intracameral injection of siRNAs targeting ZO-1 and tricellulin increased outflow facility significantly. Structural qualitative and quantitative analysis of SC inner wall by transmission electron microscopy revealed significantly more open clefts between endothelial cells treated with targeting, as opposed to non-targeting siRNA. These data substantiate the concept that the continuity of SC endothelium is an important determinant of outflow resistance, and suggest that SC endothelial TJs represent a specific target for enhancement of aqueous movement through the conventional outflow system.
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Affiliation(s)
- Lawrence C S Tam
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland
| | - Ester Reina-Torres
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland.,Department of Bioengineering, Imperial College London, London, UK
| | | | - Paul S Cassidy
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland
| | - Darragh E Crosbie
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland
| | | | | | | | - Marian M Humphries
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland
| | - Anna-Sophia Kiang
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland
| | - Jeffrey O'Callaghan
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland
| | - John J Callanan
- Ross University School of Veterinary Medicine, P. O. Box 334, Basseterre, St. Kitts, West Indies
| | - A Thomas Read
- Department of Ophthalmology and Vision Sciences, University of Toronto, Canada
| | - C Ross Ethier
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, USA
| | - Colm O'Brien
- Ophthalmology, Mater Hospital, UCD School of Medicine, Dublin, Ireland
| | | | - Matthew Campbell
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, NC, USA
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, UK
| | - Pete Humphries
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland
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