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Hein M, Qambari H, An D, Balaratnasingam C. Current understanding of subclinical diabetic retinopathy informed by histology and high-resolution in vivo imaging. Clin Exp Ophthalmol 2024; 52:464-484. [PMID: 38363022 DOI: 10.1111/ceo.14363] [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: 10/30/2023] [Revised: 01/21/2024] [Accepted: 01/26/2024] [Indexed: 02/17/2024]
Abstract
The escalating incidence of diabetes mellitus has amplified the global impact of diabetic retinopathy. There are known structural and functional changes in the diabetic retina that precede the fundus photography abnormalities which currently are used to diagnose clinical diabetic retinopathy. Understanding these subclinical alterations is important for effective disease management. Histology and high-resolution clinical imaging reveal that the entire neurovascular unit, comprised of retinal vasculature, neurons and glial cells, is affected in subclinical disease. Early functional manifestations are seen in the form of blood flow and electroretinography disturbances. Structurally, there are alterations in the cellular components of vasculature, glia and the neuronal network. On clinical imaging, changes to vessel density and thickness of neuronal layers are observed. How these subclinical disturbances interact and ultimately manifest as clinical disease remains elusive. However, this knowledge reveals potential early therapeutic targets and the need for imaging modalities that can detect subclinical changes in a clinical setting.
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Affiliation(s)
- Martin Hein
- Physiology and Pharmacology Group, Lions Eye Institute, Perth, Western Australia, Australia
- Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Western Australia, Australia
| | - Hassanain Qambari
- Physiology and Pharmacology Group, Lions Eye Institute, Perth, Western Australia, Australia
- Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Western Australia, Australia
| | - Dong An
- Physiology and Pharmacology Group, Lions Eye Institute, Perth, Western Australia, Australia
- Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Western Australia, Australia
| | - Chandrakumar Balaratnasingam
- Physiology and Pharmacology Group, Lions Eye Institute, Perth, Western Australia, Australia
- Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Western Australia, Australia
- Department of Ophthalmology, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
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2
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Brookins E, Serrano SE, Yacu GS, Finer G, Thomson BR. Non-endothelial expression of Endomucin in the mouse and human choroid. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.08.584133. [PMID: 38559191 PMCID: PMC10979916 DOI: 10.1101/2024.03.08.584133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Endomucin (EMCN) is a 261 AA transmembrane glycoprotein that is highly expressed by venous and capillary endothelial cells where it plays a role in VEGF-mediated angiogenesis and regulation of immune cell recruitment. However, it is better known as a histological marker, where it has become widespread due to the commercial availability of high-quality antibodies that work under a wide range of conditions and in many tissues. The specificity of EMCN staining has been well-validated in retinal vessels, but while it has been used extensively as a marker in other tissues of the eye, including the choroid, the pattern of expression has not been described in detail. Here, in addition to endothelial expression in the choriocapillaris and deeper vascular layers, we characterize a population of EMCN-positive perivascular cells in the mouse choroid that did not co-localize with cells expressing other endothelial markers such as PECAM1 or PODXL. To confirm that these cells represented a new population of EMCN-expressing stromal cells, we then performed single cell RNA sequencing in choroids from adult wild-type mice. Analysis of this new dataset confirmed that, in addition to endothelial cells, Emcn mRNA expression was present in choroidal pericytes and a subset of fibroblasts, but not vascular smooth muscle cells. Besides Emcn , no known endothelial gene expression was detected in these cell populations, confirming that they did not represent endothelial-stromal doublets, a common technical artifact in single cell RNA seq datasets. Instead, choroidal Emcn -expressing fibroblasts exhibited high levels of chemokine and interferon signaling genes, while Emcn -negative fibroblasts were enriched in genes encoding extracellular matrix proteins. Emcn expressing fibroblasts were also detected in published datasets from mouse brain and human choroid, suggesting that stromal Emcn expression was not unique to the choroid and was evolutionarily conserved. Together, these findings highlight unique fibroblast and pericyte populations in the choroid and provide new context for the role of EMCN in angiogenesis and immune cell recruitment.
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3
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McDonald H, Gardner-Russell J, Alarcon-Martinez L. Orchestrating Blood Flow in the Retina: Interpericyte Tunnelling Nanotube Communication. Results Probl Cell Differ 2024; 73:229-247. [PMID: 39242382 DOI: 10.1007/978-3-031-62036-2_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/09/2024]
Abstract
The retina transforms light into electrical signals, which are sent to the brain via the optic nerve to form our visual perception. This complex signal processing is performed by the retinal neuron and requires a significant amount of energy. Since neurons are unable to store energy, they must obtain glucose and oxygen from the bloodstream to produce energy to match metabolic needs. This process is called neurovascular coupling (NVC), and it is based on a precise mechanism that is not totally understood. The discovery of fine tubular processes termed tunnelling nanotubes (TNTs) set a new type of cell-to-cell communication. TNTs are extensions of the cellular membrane that allow the transfer of material between connected cells. Recently, they have been reported in the brain and retina of living mice, where they connect pericytes, which are vascular mural cells that regulate vessel diameter. Accordingly, these TNTs were termed interpericyte tunnelling nanotubes (IPTNTs), which showed a vital role in blood delivery and NVC. In this chapter, we review the involvement of TNTs in NVC and discuss their implications in retinal neurodegeneration.
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Affiliation(s)
- Hannah McDonald
- Centre for Eye Research Australia, Melbourne, VIC, Australia
- Department of Ophthalmology, University of Melbourne, Melbourne, VIC, Australia
- The Royal Victorian Eye and Ear Hospital, Melbourne, VIC, Australia
| | - Jesse Gardner-Russell
- Centre for Eye Research Australia, Melbourne, VIC, Australia
- Department of Ophthalmology, University of Melbourne, Melbourne, VIC, Australia
- The Royal Victorian Eye and Ear Hospital, Melbourne, VIC, Australia
| | - Luis Alarcon-Martinez
- Centre for Eye Research Australia, Melbourne, VIC, Australia.
- Department of Ophthalmology, University of Melbourne, Melbourne, VIC, Australia.
- The Royal Victorian Eye and Ear Hospital, Melbourne, VIC, Australia.
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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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5
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Alanazi WA, Alharbi T, El-Nagar DM, Albogami AM, Alswayyed M. Dapagliflozin Mitigates Hypotension in Lipopolysaccharide-Induced Acute Inflammation Independent of Glycemia Level. Pharmaceutics 2023; 15:1683. [PMID: 37376131 DOI: 10.3390/pharmaceutics15061683] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/31/2023] [Accepted: 06/06/2023] [Indexed: 06/29/2023] Open
Abstract
Sodium-glucose cotransporter-2 (SGLT2) inhibitors have been suggested to have anti-inflammatory properties in diabetes. The goal of this study was to evaluate the role of the SGLT2 inhibitor dapagliflozin (DAPA) in the attenuation of lipopolysaccharide (LPS)-induced hypotension. Male Wistar albino rats were divided into normal and diabetic groups and received DAPA (1 mg/kg/day) for two weeks followed by a single dose of 10 mg/kg LPS. Blood pressure was recorded throughout the study and the circulatory levels of cytokines were assessed using a multiplex array, while the aortas were harvested for analysis. DAPA attenuated the vasodilation and hypotension caused by LPS. Mean arterial pressure (MAP) was preserved in the normal and diabetic DAPA-treated septic groups (MAP = 83.17 ± 5.27, 98.43 ± 5.57 mmHg) compared to the vehicle-treated septic groups (MAP = 65.60 ± 3.31, 68.21 ± 5.88 mmHg). Most of the cytokines induced by LPS were decreased in the DAPA-treated septic groups. In the aorta, the inducible nitric oxide synthase-derived nitric oxide had lower expression in the DAPA-treated rats. In contrast, the expression of α-smooth muscle actin, a marker of the vessel's contractile state, was higher in the DAPA-treated rats in comparison with non-treated septic rats. These findings revealed that the protective role of DAPA against LPS-induced hypotension is likely to be glucose-lowering independent, as was observed in the non-diabetic septic group. Taken together, the results show that DAPA has a potential effect in the prevention of the hemodynamic disturbances of sepsis regardless of glycemia levels.
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Affiliation(s)
- Wael A Alanazi
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Turki Alharbi
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Doaa M El-Nagar
- Department of Zoology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
| | - Abdullah M Albogami
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Mohammed Alswayyed
- Department of Pathology, College of Medicine, King Saud University, Riyadh 11451, Saudi Arabia
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6
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Shan S, Liu F, Ford E, Caldwell RB, Narayanan SP, Somanath PR. Triciribine attenuates pathological neovascularization and vascular permeability in a mouse model of proliferative retinopathy. Biomed Pharmacother 2023; 162:114714. [PMID: 37080089 DOI: 10.1016/j.biopha.2023.114714] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 04/11/2023] [Accepted: 04/14/2023] [Indexed: 04/22/2023] Open
Abstract
Proliferative retinopathies are the leading cause of irreversible blindness in all ages, and there is a critical need to identify novel therapies. We investigated the impact of triciribine (TCBN), a tricyclic nucleoside analog and a weak Akt inhibitor, on retinal neurovascular injury, vascular permeability, and inflammation in oxygen-induced retinopathy (OIR). Post-natal day 7 (P7) mouse pups were subjected to OIR, and treated (i.p.) with TCBN or vehicle from P14-P16 and compared with age-matched, normoxic, vehicle or TCBN-treated controls. P17 retinas were processed for flat mounts, immunostaining, Western blotting, and qRT-PCR studies. Fluorescein angiography, electroretinography, and spectral domain optical coherence tomography were performed on days P21, P26, and P30, respectively. TCBN treatment significantly reduced pathological neovascularization, vaso-obliteration, and inflammation marked by reduced TNFα, IL6, MCP-1, Iba1, and F4/80 (macrophage/microglia markers) expression compared to the vehicle-treated OIR mouse retinas. Pathological expression of VEGF (vascular endothelial growth factor), and claudin-5 compromised the blood-retinal barrier integrity in the OIR retinas correlating with increased vascular permeability and neovascular tuft formation, which were blunted by TCBN treatment. Of note, there were no changes in the retinal architecture or retinal cell function in response to TCBN in the normoxia or OIR mice. We conclude that TCBN protects against pathological neovascularization, restores blood-retinal barrier homeostasis, and reduces retinal inflammation without adversely affecting the retinal structure and neuronal function in a mouse model of OIR. Our data suggest that TCBN may provide a novel therapeutic option for proliferative retinopathy.
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Affiliation(s)
- Shengshuai Shan
- Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Augusta, GA, 30912, USA; Research Department, Charlie Norwood VA Medical Center, Augusta, GA, 30901, USA; Vascular Biology Center, Augusta University, Augusta, GA, 30912, USA; Culver Vision Discovery Institute, Augusta University, Augusta, GA, 30912, USA
| | - Fang Liu
- Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Augusta, GA, 30912, USA; Research Department, Charlie Norwood VA Medical Center, Augusta, GA, 30901, USA; Vascular Biology Center, Augusta University, Augusta, GA, 30912, USA; Culver Vision Discovery Institute, Augusta University, Augusta, GA, 30912, USA
| | - Edith Ford
- Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Augusta, GA, 30912, USA
| | - Ruth B Caldwell
- Vascular Biology Center, Augusta University, Augusta, GA, 30912, USA; Culver Vision Discovery Institute, Augusta University, Augusta, GA, 30912, USA
| | - S Priya Narayanan
- Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Augusta, GA, 30912, USA; Research Department, Charlie Norwood VA Medical Center, Augusta, GA, 30901, USA; Vascular Biology Center, Augusta University, Augusta, GA, 30912, USA; Culver Vision Discovery Institute, Augusta University, Augusta, GA, 30912, USA.
| | - Payaningal R Somanath
- Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Augusta, GA, 30912, USA; Research Department, Charlie Norwood VA Medical Center, Augusta, GA, 30901, USA; Culver Vision Discovery Institute, Augusta University, Augusta, GA, 30912, USA.
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7
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Hwang J, Kiick KL, Sullivan MO. VEGF-Encoding, Gene-Activated Collagen-Based Matrices Promote Blood Vessel Formation and Improved Wound Repair. ACS APPLIED MATERIALS & INTERFACES 2023; 15:16434-16447. [PMID: 36961242 PMCID: PMC10154048 DOI: 10.1021/acsami.2c23022] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Disruption in vascularization during wound repair can severely impair healing. Proangiogenic growth factor therapies have shown great healing potential; however, controlling growth factor activity and cellular behavior over desired healing time scales remains challenging. In this study, we evaluated collagen-mimetic peptide (CMP) tethers for their capacity to control growth factor gene transfer and growth factor activity using our recently developed gene-activated hyaluronic acid-collagen matrix (GAHCM). GAHCM was comprised of DNA/polyethyleneimine (PEI) polyplexes that were retained on hyaluronic acid (HA)-collagen hydrogels using CMPs. We hypothesized that using CMP-collagen tethers to control vascular endothelial growth factor-A (VEGF-A) gene delivery in fibroblasts would provide a powerful strategy to modulate the proangiogenic behaviors of endothelial cells (ECs) for blood vessel formation, resulting in enhanced wound repair. In co-culture experiments, we observed that CMP-modified GAHCM induced tunable gene delivery in fibroblasts as predicted, and correspondingly, VEGF-A produced by the fibroblasts led to increased growth and persistent migration of ECs for at least 7 days, as compared to non-CMP-modified GAHCM. Moreover, when ECs were exposed to fibroblast-containing VEGF-GAHCM with higher levels of CMP modification (50% CMP-PEI, or 50 CP), high CD31 expression was stimulated, resulting in the formation of an interconnected EC network with a significantly higher network volume and a larger diameter network structure than controls. Application of VEGF-GAHCM with 50 CP in murine splinted excisional wounds facilitated prolonged prohealing and proangiogenic responses resulting in increased blood vessel formation, improved granulation tissue formation, faster re-epithelialization, and overall enhanced repair. These findings suggest the benefits of CMP-collagen tethers as useful tools to control gene transfer and growth factor activity for improved treatment of wounds.
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Affiliation(s)
- Jeongmin Hwang
- Department of Biomedical Engineering, University of Delaware, Newark, DE, USA, 19713
| | - Kristi L. Kiick
- Department of Biomedical Engineering, University of Delaware, Newark, DE, USA, 19713
- Department of Materials Science and Engineering, University of Delaware, Newark, DE, USA, 19716
| | - Millicent O. Sullivan
- Department of Biomedical Engineering, University of Delaware, Newark, DE, USA, 19713
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA, 19716
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Choi SU, Kim YJ, Lee JY, Lee J, Yoon YH. Qualitative and quantitative evaluation of diabetic choroidopathy using ultra-widefield indocyanine green angiography. Sci Rep 2023; 13:2577. [PMID: 36781980 PMCID: PMC9925819 DOI: 10.1038/s41598-023-29216-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 01/31/2023] [Indexed: 02/15/2023] Open
Abstract
To investigate angiographic characteristic features of diabetic choroidopathy, as well as choroidal vascular density (CVD) and fractal dimension (CFD) in diabetic eyes and controls using ultra-widefield (UWF) indocyanine green angiography (ICGA). All patients underwent UWF fluorescein angiography and ICGA. Using imageJ software, CVD and CFD was analyzed. SFCT was assessed using spectral-domain optical coherence tomography. The image parameters were compared based on the DR stage and the presence of diabetic macular edema (DME). One-hundred six eyes from 63 patients (59.11 ± 16.31 years; male [%]: 23 [36.5%]) were included in the DM group, and 40 eyes from 22 subjects were included in the control group. The DM group had a mean age of 59.11 ± 16.31 years and a mean HbA1c percentage of 7.72 ± 1.28%. The most common ICGA findings of DC were choroidal hyperpermeability (57.5%), hypofluorescent spots (48.1%). Salt and pepper pattern (19.8%), inverted inflow phenomenon (3.8%), choroidal arterial tortuosity (24.5%), and late choroidal non-perfusion (6.6%) were more common in advanced DR. The CVD, CFD, and SFCT increased as the DR severity progressed. The DME group had a significantly higher CFD and SFCT than the non-DME group (P < 0.001 and P = 0.019, respectively). The qualitative and quantitative UWF ICGA image analysis revealed that choroidal blood vessels became dilated, complex, and hyperpermeable as the DR progressed. These features of diabetic choroidopathy (DC) were more severe in eyes with DME than the non-DME eyes.
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Affiliation(s)
- Sang Uk Choi
- Department of Ophthalmology, Chung-Ang University Hospital, Chung-Ang University, College of Medicine, Seoul, South Korea
- Department of Ophthalmology, Asan Medical Center, University of Ulsan, College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, Korea
| | - Yoon Jeon Kim
- Department of Ophthalmology, Asan Medical Center, University of Ulsan, College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, Korea
- Asan Diabetes Center, Asan Medical Center, Seoul, South Korea
| | - Joo Yong Lee
- Department of Ophthalmology, Asan Medical Center, University of Ulsan, College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, Korea
- Asan Diabetes Center, Asan Medical Center, Seoul, South Korea
| | - Junyeop Lee
- Department of Ophthalmology, Asan Medical Center, University of Ulsan, College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, Korea.
- Asan Diabetes Center, Asan Medical Center, Seoul, South Korea.
| | - Young Hee Yoon
- Department of Ophthalmology, Asan Medical Center, University of Ulsan, College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, Korea.
- Asan Diabetes Center, Asan Medical Center, Seoul, South Korea.
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9
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Schreiner TG, Creangă-Murariu I, Tamba BI, Lucanu N, Popescu BO. In Vitro Modeling of the Blood–Brain Barrier for the Study of Physiological Conditions and Alzheimer’s Disease. Biomolecules 2022; 12:biom12081136. [PMID: 36009030 PMCID: PMC9405874 DOI: 10.3390/biom12081136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/09/2022] [Accepted: 08/16/2022] [Indexed: 11/16/2022] Open
Abstract
The blood–brain barrier (BBB) is an essential structure for the maintenance of brain homeostasis. Alterations to the BBB are linked with a myriad of pathological conditions and play a significant role in the onset and evolution of neurodegenerative diseases, including Alzheimer’s disease. Thus, a deeper understanding of the BBB’s structure and function is mandatory for a better knowledge of neurodegenerative disorders and the development of effective therapies. Because studying the BBB in vivo imposes overwhelming difficulties, the in vitro approach remains the main possible way of research. With many in vitro BBB models having been developed over the last years, the main aim of this review is to systematically present the most relevant designs used in neurological research. In the first part of the article, the physiological and structural–functional parameters of the human BBB are detailed. Subsequently, available BBB models are presented in a comparative approach, highlighting their advantages and limitations. Finally, the new perspectives related to the study of Alzheimer’s disease with the help of novel devices that mimic the in vivo human BBB milieu gives the paper significant originality.
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Affiliation(s)
- Thomas Gabriel Schreiner
- Faculty of Medicine, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest, Romania
- Department of Neurology, “Grigore T. Popa” University of Medicine and Pharmacy, 700115 Iasi, Romania
- Department of Electrical Measurements and Materials, Faculty of Electrical Engineering and Information Technology, Gheorghe Asachi Technical University of Iasi, 21-23 Professor Dimitrie Mangeron Blvd., 700050 Iasi, Romania
- Correspondence:
| | - Ioana Creangă-Murariu
- Advanced Research and Development Center for Experimental Medicine (CEMEX), “Grigore T. Popa” University of Medicine and Pharmacy, Universitatii Str., No. 16, 700155 Iasi, Romania
| | - Bogdan Ionel Tamba
- Advanced Research and Development Center for Experimental Medicine (CEMEX), “Grigore T. Popa” University of Medicine and Pharmacy, Universitatii Str., No. 16, 700155 Iasi, Romania
| | - Nicolae Lucanu
- Department of Applied Electronics and Intelligent Systems, Faculty of Electronics, Telecommunications and Information Technology, Gheorghe Asachi Technical University of Iasi, 21-23 Professor Dimitrie Mangeron Blvd., 700050 Iasi, Romania
| | - Bogdan Ovidiu Popescu
- Faculty of Medicine, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest, Romania
- Neurology Department, Colentina Clinical Hospital, 020125 Bucharest, Romania
- Laboratory of Cell Biology, Neurosciences and Experimental Myology, “Victor Babes” National Institute of Pathology, 050096 Bucharest, Romania
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10
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An D, Chung-Wah-Cheong J, Yu DY, Balaratnasingam C. Alpha-Smooth Muscle Actin Expression and Parafoveal Blood Flow Pathways Are Altered in Preclinical Diabetic Retinopathy. Invest Ophthalmol Vis Sci 2022; 63:8. [PMID: 35522303 PMCID: PMC9078056 DOI: 10.1167/iovs.63.5.8] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To investigate differences in alpha smooth muscle actin (αSMA) expression and parafoveal blood flow pathways in diabetic retinopathy (DR). Methods Human donor eyes from healthy subjects (n = 8), patients with diabetes but no DR (DR-; n = 7), and patients with clinical DR (DR+; n = 13) were perfusion labeled with antibodies targeting αSMA, lectin, collagen IV, and filamentous actin. High-resolution confocal scanning laser microscopy was used to quantify αSMA staining and capillary density in the parafoveal circulation. Quantitative analyses of connections between retinal arteries and veins within the superficial vascular plexus (SVP), intermediate capillary plexus (ICP) and deep capillary plexus (DCP) were performed. Results Mean age between the groups was not different (P = 0.979). αSMA staining was seen in the SVP and ICP of all groups. The DCP was predominantly devoid of αSMA staining in control eyes but increased in a disease stage-specific manner in the DR- and DR+ groups. The increase in αSMA staining was localized to pericytes and endothelia of terminal arterioles and adjacent capillary segments. Capillary density was less in the DCP in the DR+ group (P < 0.001). ICP of the DR- and DR+ groups received more direct arteriole supplies than the control group (P < 0.001). Venous outflow pathways were not altered (all P > 0.284). Conclusions Alterations in αSMA and vascular inflow pathways in preclinical DR suggest that perfusion abnormalities precede structural vascular changes such as capillary loss. Preclinical DR may be characterized by a "steal" phenomenon where blood flow is preferentially diverted from the SVP to the ICP and DCP.
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Affiliation(s)
- Dong An
- Lions Eye Institute, Nedlands, Western Australia, Australia.,Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Western Australia, Australia
| | | | - Dao-Yi Yu
- Lions Eye Institute, Nedlands, Western Australia, Australia.,Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Western Australia, Australia
| | - Chandrakumar Balaratnasingam
- Lions Eye Institute, Nedlands, Western Australia, Australia.,Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Western Australia, Australia.,Department of Ophthalmology, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia
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11
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Effects of Cadmium Exposure on Leydig Cells and Blood Vessels in Mouse Testis. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19042416. [PMID: 35206604 PMCID: PMC8878469 DOI: 10.3390/ijerph19042416] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/25/2021] [Revised: 02/17/2022] [Accepted: 02/17/2022] [Indexed: 11/17/2022]
Abstract
Environmental exposure to cadmium (Cd) contributes to a decline in the quality of human semen. Although the testis is sensitive to Cd exposure, the mechanism underlying how cadmium affects the testis remains to be defined. In this study, male mice were treated with intraperitoneal injections of 0, 0.5, 1.5 and 2.5 mg CdCl2/kg/day for 10 days, respectively. Both the testicular weight and the 3β-HSD activity of Leydig cells were significantly reduced with the administration of 2.5 mg CdCl2/kg/day. The height of endothelial cells in the interstitial blood vessels significantly increased with the use of 2.5 mg CdCl2/kg/day compared with the control. Western blot data showed that the protein levels of CD31, αSMA, caveolin and Ng2 increased with cadmium exposure, and this increase was particularly significant with the administration of 2.5 mg CdCl2/kg/day. CD31, αSMA, caveolin and Ng2 are related to angiogenesis. Based on our data, cadmium exposure may stimulate the proliferation of the mural cells and endothelial cells of blood vessels, which may lead to abnormal function of the testis.
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Ly6c as a New Marker of Mouse Blood Vessels: Qualitative and Quantitative Analyses on Intact and Ischemic Retinas. Int J Mol Sci 2021; 23:ijms23010019. [PMID: 35008441 PMCID: PMC8744623 DOI: 10.3390/ijms23010019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 12/14/2021] [Accepted: 12/16/2021] [Indexed: 12/01/2022] Open
Abstract
Ly6c is an antigen commonly used to differentiate between classical and non-classical monocytes/macrophages. Here we show its potential as a marker of the mouse vasculature, particularly of the retinal vascular plexuses. Ly6c was immunodetected in several tissues of C57BL/6 mice using isolectin IB4 as the control of vasculature staining. In the retina, Ly6c expression was analyzed qualitatively and quantitatively in intact, ischemic, and contralateral retinas from 0 to 30 days after the insult. Ly6c expression was observed in all organs and tissues tested, with a brighter signal and more homogeneous staining than the IB4. In the retinas, Ly6c was well expressed, allowing a detailed study of their anatomy. The three retinal plexuses were morphologically different, and from the superficial to the deep one occupied 15 ± 2, 24 ± 7, and 38 ± 1.4 percent of the retinal surface, respectively. In the injured retinas, there was extravasation of the classically activated monocyte/macrophages (Ly6chigh) and the formation of new vessels in the superficial plexus, increasing the area occupied by it to 25 ± 1%. In the contralateral retinas, the superficial plexus area decreased gradually, reaching significance at 30 days, and Ly6c expression progressively disappeared in the intermediate and deep plexuses. Although the role of Ly6c in vascular endothelial cell function is still not completely understood, we demonstrate here that Ly6c can be used as a new specific marker of the mouse vasculature and to assess, qualitatively and quantitatively, vascular changes in health and disease.
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Procter TV, Williams A, Montagne A. Interplay between brain pericytes and endothelial cells in dementia. THE AMERICAN JOURNAL OF PATHOLOGY 2021; 191:1917-1931. [PMID: 34329605 DOI: 10.1016/j.ajpath.2021.07.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 06/23/2021] [Accepted: 07/02/2021] [Indexed: 02/06/2023]
Abstract
Dementia is becoming an increasingly important disease due to an aging population and limited treatment options. Cerebral small vessel disease (cSVD) and Alzheimer's disease (AD) are the two most common causes of dementia with vascular dysfunction being a large component of both their pathophysiologies. The neurogliovascular unit (NVU), and in particular the blood-brain barrier (BBB) are required for maintaining brain homeostasis. A complex interaction exists between the endothelial cells, which line the blood vessels and pericytes, which surround them in the NVU. Disruption of the BBB occurs in dementia precipitating cognitive decline. In this review, we highlight how dysfunction of the endothelial-pericyte crosstalk contributes to dementia, focusing on cSVD and AD. This review examines how loss of pericyte coverage occurs and subsequent downstream changes. Furthermore, it examines how disruption to intimate crosstalk between endothelial cells and pericytes leads to alterations in cerebral blood flow, transcription, neuroinflammation and transcytosis contributing to breakdown of the BBB. This review illustrates how cumulation of loss of endothelial-pericyte crosstalk is a major driving force in dementia pathology.
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Affiliation(s)
- Tessa V Procter
- Centre for Regenerative Medicine, Institute for Regeneration and Repair, University of Edinburgh, Edinburgh BioQuarter, Edinburgh, UK
| | - Anna Williams
- Centre for Regenerative Medicine, Institute for Regeneration and Repair, University of Edinburgh, Edinburgh BioQuarter, Edinburgh, UK; UK Dementia Research Institute, Edinburgh Medical School, University of Edinburgh, Edinburgh, UK
| | - Axel Montagne
- UK Dementia Research Institute, Edinburgh Medical School, University of Edinburgh, Edinburgh, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK.
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14
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Brinks J, van Dijk EHC, Klaassen I, Schlingemann RO, Kielbasa SM, Emri E, Quax PHA, Bergen AA, Meijer OC, Boon CJF. Exploring the choroidal vascular labyrinth and its molecular and structural roles in health and disease. Prog Retin Eye Res 2021; 87:100994. [PMID: 34280556 DOI: 10.1016/j.preteyeres.2021.100994] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/04/2021] [Accepted: 07/07/2021] [Indexed: 12/14/2022]
Abstract
The choroid is a key player in maintaining ocular homeostasis and plays a role in a variety of chorioretinal diseases, many of which are poorly understood. Recent advances in the field of single-cell RNA sequencing have yielded valuable insights into the properties of choroidal endothelial cells (CECs). Here, we review the role of the choroid in various physiological and pathophysiological mechanisms, focusing on the role of CECs. We also discuss new insights regarding the phenotypic properties of CECs, CEC subpopulations, and the value of measuring transcriptomics in primary CEC cultures derived from post-mortem eyes. In addition, we discuss key phenotypic, structural, and functional differences that distinguish CECs from other endothelial cells such as retinal vascular endothelial cells. Understanding the specific clinical and molecular properties of the choroid will shed new light on the pathogenesis of the broad clinical range of chorioretinal diseases such as age-related macular degeneration, central serous chorioretinopathy and other diseases within the pachychoroid spectrum, uveitis, and diabetic choroidopathy. Although our knowledge is still relatively limited with respect to the clinical features and molecular pathways that underlie these chorioretinal diseases, we summarise new approaches and discuss future directions for gaining new insights into these sight-threatening diseases and highlight new therapeutic strategies such as pluripotent stem cell‒based technologies and gene therapy.
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Affiliation(s)
- J Brinks
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - E H C van Dijk
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - I Klaassen
- Ocular Angiogenesis Group, Departments of Ophthalmology and Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands
| | - R O Schlingemann
- Ocular Angiogenesis Group, Departments of Ophthalmology and Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands; Department of Ophthalmology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands; Department of Ophthalmology, University of Lausanne, Jules Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
| | - S M Kielbasa
- Department of Medical Statistics and Bioinformatics, Leiden University Medical Center, Leiden, the Netherlands
| | - E Emri
- Department of Clinical Genetics, Section of Ophthalmogenetics, Amsterdam University Medical Centers, Amsterdam, the Netherlands
| | - P H A Quax
- Department of Vascular Surgery, Leiden University Medical Center, Leiden, the Netherlands; Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | - A A Bergen
- Department of Clinical Genetics, Section of Ophthalmogenetics, Amsterdam University Medical Centers, Amsterdam, the Netherlands
| | - O C Meijer
- Department of Medicine, Division of Endocrinology and Metabolism, Leiden University Medical Center, Leiden, the Netherlands
| | - C J F Boon
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands; Department of Ophthalmology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands.
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15
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Alarcon-Martinez L, Yemisci M, Dalkara T. Pericyte morphology and function. Histol Histopathol 2021; 36:633-643. [PMID: 33595091 DOI: 10.14670/hh-18-314] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The proper delivery of blood is essential for healthy neuronal function. The anatomical substrate for this precise mechanism is the neurovascular unit, which is formed by neurons, glial cells, endothelia, smooth muscle cells, and pericytes. Based on their particular location on the vessel wall, morphology, and protein expression, pericytes have been proposed as cells capable of regulating capillary blood flow. Pericytes are located around the microvessels, wrapping them with their processes. Their morphology and protein expression substantially vary along the vascular tree. Their contractibility is mediated by a unique cytoskeleton organization formed by filaments of actin that allows pericyte deformability with the consequent mechanical force transferred to the extracellular matrix for changing the diameter. Pericyte ultrastructure is characterized by large mitochondria likely to provide energy to regulate intracellular calcium concentration and fuel contraction. Accordingly, pericytes with compromised energy show a sustained intracellular calcium increase that leads to persistent microvascular constriction. Pericyte morphology is highly plastic and adapted for varying contractile capability along the microvascular tree, making pericytes ideal cells to regulate the capillary blood flow in response to local neuronal activity. Besides the vascular regulation, pericytes also play a role in the maintenance of the blood-brain/retina barrier, neovascularization and angiogenesis, and leukocyte transmigration. Here, we review the morphological and functional features of the pericytes as well as potential specific markers for the study of pericytes in the brain and retina.
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Affiliation(s)
- Luis Alarcon-Martinez
- Department of Neuroscience and Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Université de Montréal, Montréal, QC, Canada.
| | - Muge Yemisci
- Department of Neurology, Faculty of Medicine, Hacettepe University, Ankara, Turkey.,Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
| | - Turgay Dalkara
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
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16
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Kovács-Öller T, Ivanova E, Szarka G, Tengölics ÁJ, Völgyi B, Sagdullaev BT. Imatinib Sets Pericyte Mosaic in the Retina. Int J Mol Sci 2020; 21:E2522. [PMID: 32260484 PMCID: PMC7177598 DOI: 10.3390/ijms21072522] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 03/25/2020] [Accepted: 04/01/2020] [Indexed: 02/07/2023] Open
Abstract
The nervous system demands an adequate oxygen and metabolite exchange, making pericytes (PCs), the only vasoactive cells on the capillaries, essential to neural function. Loss of PCs is a hallmark of multiple diseases, including diabetes, Alzheimer's, amyotrophic lateral sclerosis (ALS) and Parkinson's. Platelet-derived growth factor receptors (PDGFRs) have been shown to be critical to PC function and survival. However, how PDGFR-mediated PC activity affects vascular homeostasis is not fully understood. Here, we tested the hypothesis that imatinib, a chemotherapeutic agent and a potent PDGFR inhibitor, alters PC distribution and thus induces vascular atrophy. We performed a morphometric analysis of the vascular elements in sham control and imatinib-treated NG2-DsRed mice. Vascular morphology and the integrity of the blood-retina barrier (BRB) were evaluated using blood albumin labeling. We found that imatinib decreased the number of PCs and blood vessel (BV) coverage in all retinal vascular layers; this was accompanied by a shrinkage of BV diameters. Surprisingly, the total length of capillaries was not altered, suggesting a preferential effect of imatinib on PCs. Furthermore, blood-retina barrier disruption was not evident. In conclusion, our data suggest that imatinib could help in treating neurovascular diseases and serve as a model for PC loss, without BRB disruption.
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Affiliation(s)
- Tamás Kovács-Öller
- János Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary
- Retinal Electrical Synapses Research Group, National Brain Research Program (NAP 2.0), Hungarian Academy of Sciences, 1051 Budapest, Hungary
- Burke Neurological Institute, Department of Ophthalmology, Weill Cornell Medicine, White Plains, NY 10605, USA
- Department of Experimental Zoology and Neurobiology, University of Pécs, 7624 Pécs, Hungary
| | - Elena Ivanova
- Burke Neurological Institute, Department of Ophthalmology, Weill Cornell Medicine, White Plains, NY 10605, USA
| | - Gergely Szarka
- János Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary
- Retinal Electrical Synapses Research Group, National Brain Research Program (NAP 2.0), Hungarian Academy of Sciences, 1051 Budapest, Hungary
| | - Ádám J Tengölics
- János Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary
- Retinal Electrical Synapses Research Group, National Brain Research Program (NAP 2.0), Hungarian Academy of Sciences, 1051 Budapest, Hungary
- Medical School, University of Pécs, 7624 Pécs, Hungary
| | - Béla Völgyi
- János Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary
- Retinal Electrical Synapses Research Group, National Brain Research Program (NAP 2.0), Hungarian Academy of Sciences, 1051 Budapest, Hungary
- Department of Experimental Zoology and Neurobiology, University of Pécs, 7624 Pécs, Hungary
- Medical School, University of Pécs, 7624 Pécs, Hungary
| | - Botir T Sagdullaev
- Burke Neurological Institute, Department of Ophthalmology, Weill Cornell Medicine, White Plains, NY 10605, USA
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