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Suanno G, Genna VG, Maurizi E, Dieh AA, Griffith M, Ferrari G. Cell therapy in the cornea: The emerging role of microenvironment. Prog Retin Eye Res 2024; 102:101275. [PMID: 38797320 DOI: 10.1016/j.preteyeres.2024.101275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 05/22/2024] [Accepted: 05/23/2024] [Indexed: 05/29/2024]
Abstract
The cornea is an ideal testing field for cell therapies. Its highly ordered structure, where specific cell populations are sequestered in different layers, together with its accessibility, has allowed the development of the first stem cell-based therapy approved by the European Medicine Agency. Today, different techniques have been proposed for autologous and allogeneic limbal and non-limbal cell transplantation. Cell replacement has also been attempted in cases of endothelial cell decompensation as it occurs in Fuchs dystrophy: injection of cultivated allogeneic endothelial cells is now in advanced phases of clinical development. Recently, stromal substitutes have been developed with excellent integration capability and transparency. Finally, cell-derived products, such as exosomes obtained from different sources, have been investigated for the treatment of severe corneal diseases with encouraging results. Optimization of the success rate of cell therapies obviously requires high-quality cultured cells/products, but the role of the surrounding microenvironment is equally important to allow engraftment of transplanted cells, to preserve their functions and, ultimately, lead to restoration of tissue integrity and transparency of the cornea.
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Affiliation(s)
- Giuseppe Suanno
- Vita-Salute San Raffaele University, Milan, Italy; Eye Repair Unit, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | | | - Eleonora Maurizi
- Centre for Regenerative Medicine ''S. Ferrari'', University of Modena and Reggio Emilia, Modena, Italy
| | - Anas Abu Dieh
- Maisonneuve-Rosemont Hospital Research Centre, Montreal, Quebec, Canada
| | - May Griffith
- Maisonneuve-Rosemont Hospital Research Centre, Montreal, Quebec, Canada.
| | - Giulio Ferrari
- Vita-Salute San Raffaele University, Milan, Italy; Eye Repair Unit, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy; Ophthalmology Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy.
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2
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Meek KM, Knupp C, Lewis PN, Morgan SR, Hayes S. Structural control of corneal transparency, refractive power and dynamics. Eye (Lond) 2024:10.1038/s41433-024-02969-7. [PMID: 38396030 DOI: 10.1038/s41433-024-02969-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 12/11/2023] [Accepted: 01/26/2024] [Indexed: 02/25/2024] Open
Abstract
The cornea needs to be transparent to visible light and precisely curved to provide the correct refractive power. Both properties are governed by its structure. Corneal transparency arises from constructive interference of visible light due to the relatively ordered arrangement of collagen fibrils in the corneal stroma. The arrangement is controlled by the negatively charged proteoglycans surrounding the fibrils. Small changes in fibril organisation can be tolerated but larger changes cause light scattering. Corneal keratocytes do not scatter light because their refractive index matches that of the surrounding matrix. When activated, however, they become fibroblasts that have a lower refractive index. Modelling shows that this change in refractive index significantly increases light scatter. At the microscopic level, the corneal stroma has a lamellar structure, the parallel collagen fibrils within each lamella making a large angle with those of adjacent lamellae. X-ray scattering has shown that the lamellae have preferred orientations in the human cornea: inferior-superior and nasal-temporal in the central cornea and circumferential at the limbus. The directions at the centre of the cornea may help withstand the pull of the extraocular muscles whereas the pseudo-circular arrangement at the limbus supports the change in curvature between the cornea and sclera. Elastic fibres are also present; in the limbus they contain fibrillin microfibrils surrounding an elastin core, whereas at the centre of the cornea, they exist as thin bundles of fibrillin-rich microfibrils. We present a model based on the structure described above that may explain how the cornea withstands repeated pressure changes due to the ocular pulse.
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Affiliation(s)
- Keith M Meek
- Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK.
| | - Carlo Knupp
- Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Philip N Lewis
- Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Siân R Morgan
- Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Sally Hayes
- Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
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3
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Folson AA, Agyapong KO, Dey D, Eghan P, Quaye B. Marfan syndrome in a Ghanaian male: The diagnostic challenges. Clin Case Rep 2024; 12:e8494. [PMID: 38380377 PMCID: PMC10876919 DOI: 10.1002/ccr3.8494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 01/15/2024] [Accepted: 01/19/2024] [Indexed: 02/22/2024] Open
Abstract
Marfan syndrome (MFS) is an autosomal dominantly inherited condition that has varying phenotypic expressions. This case report describes one such African patient, from Ghana, who had typical clinical and imaging traits of MFS but was first diagnosed incidentally at the age of 23 years. In this report, we explore the challenges of early diagnosis in this population.
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Affiliation(s)
- Aba A. Folson
- Department of Internal Medicine and Therapeutics, School of MedicineUniversity of Health and Allied SciencesHoGhana
| | | | - Dzifa Dey
- Department of Medicine and TherapeuticsUniversity of Ghana Medical School, College of Health Sciences, University of GhanaAccraGhana
| | - Philip Eghan
- Department of RadiologyUniversity of Ghana Medical CentreAccraGhana
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4
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Sun M, Koudouna E, Cogswell D, Avila MY, Koch M, Espana EM. Collagen XII Regulates Corneal Stromal Structure by Modulating Transforming Growth Factor-β Activity. THE AMERICAN JOURNAL OF PATHOLOGY 2022; 192:308-319. [PMID: 34774848 PMCID: PMC8908044 DOI: 10.1016/j.ajpath.2021.10.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 10/12/2021] [Accepted: 10/19/2021] [Indexed: 02/03/2023]
Abstract
Collagen XII is a regulator of corneal stroma structure and function. The current study examined the role of collagen XII in regulating corneal stromal transforming growth factor (TGF)-β activation and latency. Specifically, with the use of conventional collagen XII null mouse model, the role of collagen XII in the regulation of TGF-β latency and activity in vivo was investigated. Functional quantification of latent TGF-β in stromal matrix was performed by using transformed mink lung reporter cells that produce luciferase as a function of active TGF-β. Col12a1 knockdown with shRNA was used to test the role of collagen XII in TGF-β activation. Col12a1-/- hypertrophic stromata were observed with keratocyte hyperplasia. Increased collagen fibril forward signal was found by second harmonic generation microscopy in the absence of collagen XII. Collagen XII regulated mRNA synthesis of Serpine1, Col1a1, and Col5a1 and deposition of collagens in the extracellular matrix. A functional plasminogen activator inhibitor luciferase assay showed that collagen XII is necessary for latent TGF-β storage in the extracellular matrix and that collagen XII down-regulates active TGF-β. Collagen XII dictates stromal structure and function by regulating TGF-β activity. A hypertrophic phenotype in Col12a1-/- corneal tissue can be explained by abnormal up-regulation of TGF-β activation and decreased latent storage.
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Affiliation(s)
- Mei Sun
- Cornea and External Disease, Department of Ophthalmology, Department of Molecular Pharmacology and Physiology, Tampa, Florida
| | - Elena Koudouna
- Structural Biophysics, School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Devon Cogswell
- Cornea and External Disease, Department of Ophthalmology, Department of Molecular Pharmacology and Physiology, Tampa, Florida
| | - Marcel Y. Avila
- Department of Ophthalmology, Universidad Nacional de Colombia, Bogota, Colombia
| | - Manuel Koch
- Institute for Dental Research and Oral Musculoskeletal Biology, Center for Biochemistry, University of Cologne, Cologne, Germany
| | - Edgar M. Espana
- Cornea and External Disease, Department of Ophthalmology, Department of Molecular Pharmacology and Physiology, Tampa, Florida,Morsani College of Medicine, University of South Florida, Tampa, Florida,Address correspondence to Edgar M. Espana, M.D., Ophthalmology, University of South Florida, Morsani College of Medicine, 13330 USF Laurel Dr., 4th Floor, MDC11, Tampa, FL 33612.
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5
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Abstract
Marfan syndrome (MFS) is an autosomal dominant, age-related but highly penetrant condition with substantial intrafamilial and interfamilial variability. MFS is caused by pathogenetic variants in FBN1, which encodes fibrillin-1, a major structural component of the extracellular matrix that provides support to connective tissues, particularly in arteries, the pericondrium and structures in the eye. Up to 25% of individuals with MFS have de novo variants. The most prominent manifestations of MFS are asymptomatic aortic root aneurysms, aortic dissections, dislocation of the ocular lens (ectopia lentis) and skeletal abnormalities that are characterized by overgrowth of the long bones. MFS is diagnosed based on the Ghent II nosology; genetic testing confirming the presence of a FBN1 pathogenetic variant is not always required for diagnosis but can help distinguish MFS from other heritable thoracic aortic disease syndromes that can present with skeletal features similar to those in MFS. Untreated aortic root aneurysms can progress to life-threatening acute aortic dissections. Management of MFS requires medical therapy to slow the rate of growth of aneurysms and decrease the risk of dissection. Routine surveillance with imaging techniques such as transthoracic echocardiography, CT or MRI is necessary to monitor aneurysm growth and determine when to perform prophylactic repair surgery to prevent an acute aortic dissection.
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6
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Lewis PN, Young RD, Souza RB, Quantock AJ, Meek KM. Contrast-Enhanced Tissue Processing of Fibrillin-Rich Elastic Fibres for 3D Visualization by Volume Scanning Electron Microscopy. Methods Protoc 2021; 4:mps4030056. [PMID: 34449675 PMCID: PMC8395850 DOI: 10.3390/mps4030056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/04/2021] [Accepted: 08/11/2021] [Indexed: 11/16/2022] Open
Abstract
Elastic fibres constitute an important component of the extracellular matrix and currently are the subject of intensive study in order to elucidate their assembly, function and involvement in cell-matrix interactions and disease. However, few studies to date have investigated the 3D architecture of the elastic fibre system in bulk tissue. We describe a protocol for preparation of tissue samples, including primary fixation and backscatter electron contrast-enhancement steps, through dehydration into stable resin-embedded blocks for volume electron microscopy. The use of low molecular weight tannic acid and alcoholic lead staining are critical stages in this procedure. Block preparation by ultramicrotomy and evaporative metal coating prior to microscopical examination are also described. We present images acquired from serial block face scanning electron microscopy of cornea and aorta showing target structures clearly differentiated from cells and other matrix components. The processing method imparts high contrast to fibrillin-containing elastic fibres, thus facilitating their segmentation and rendering into 3D reconstructions by image analysis software from large serial image datasets.
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Affiliation(s)
- Philip N. Lewis
- Structural Biophysics Research Group, School of Optometry & Vision Sciences, Cardiff University, Cardiff CF24 4HQ, UK; (R.D.Y.); (A.J.Q.); (K.M.M.)
- Correspondence:
| | - Robert D. Young
- Structural Biophysics Research Group, School of Optometry & Vision Sciences, Cardiff University, Cardiff CF24 4HQ, UK; (R.D.Y.); (A.J.Q.); (K.M.M.)
| | - R. B. Souza
- Department of Genetics and Evolutionary Biology, University of São Paulo, Rua de Matão 05508-090, Brazil;
| | - Andrew J. Quantock
- Structural Biophysics Research Group, School of Optometry & Vision Sciences, Cardiff University, Cardiff CF24 4HQ, UK; (R.D.Y.); (A.J.Q.); (K.M.M.)
| | - Keith M. Meek
- Structural Biophysics Research Group, School of Optometry & Vision Sciences, Cardiff University, Cardiff CF24 4HQ, UK; (R.D.Y.); (A.J.Q.); (K.M.M.)
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7
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Courson JA, Landry PT, Do T, Spehlmann E, Lafontant PJ, Patel N, Rumbaut RE, Burns AR. Serial Block-Face Scanning Electron Microscopy (SBF-SEM) of Biological Tissue Samples. J Vis Exp 2021:10.3791/62045. [PMID: 33843931 PMCID: PMC8225236 DOI: 10.3791/62045] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Serial block-face scanning electron microscopy (SBF-SEM) allows for the collection of hundreds to thousands of serially-registered ultrastructural images, offering an unprecedented three-dimensional view of tissue microanatomy. While SBF-SEM has seen an exponential increase in use in recent years, technical aspects such as proper tissue preparation and imaging parameters are paramount for the success of this imaging modality. This imaging system benefits from the automated nature of the device, allowing one to leave the microscope unattended during the imaging process, with the automated collection of hundreds of images possible in a single day. However, without appropriate tissue preparation cellular ultrastructure can be altered in such a way that incorrect or misleading conclusions might be drawn. Additionally, images are generated by scanning the block-face of a resin-embedded biological sample and this often presents challenges and considerations that must be addressed. The accumulation of electrons within the block during imaging, known as "tissue charging," can lead to a loss of contrast and an inability to appreciate cellular structure. Moreover, while increasing electron beam intensity/voltage or decreasing beam-scanning speed can increase image resolution, this can also have the unfortunate side effect of damaging the resin block and distorting subsequent images in the imaging series. Here we present a routine protocol for the preparation of biological tissue samples that preserves cellular ultrastructure and diminishes tissue charging. We also provide imaging considerations for the rapid acquisition of high-quality serial-images with minimal damage to the tissue block.
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Affiliation(s)
- Justin A. Courson
- University of Houston, College of Optometry, Houston, TX,
United States of America
| | - Paul T. Landry
- University of Houston, College of Optometry, Houston, TX,
United States of America
| | - Thao Do
- University of Houston, College of Optometry, Houston, TX,
United States of America
| | - Eric Spehlmann
- DePauw University, Department of Biology, Greencastle, IN,
United States of America
| | - Pascal J. Lafontant
- DePauw University, Department of Biology, Greencastle, IN,
United States of America
| | - Nimesh Patel
- University of Houston, College of Optometry, Houston, TX,
United States of America
| | - Rolando E. Rumbaut
- Center for Translational Research on Inflammatory Diseases
(CTRID), Michael E. DeBakey Veterans Affairs Medical Center, Houston, TX, United
States of America,Baylor College of Medicine, Children’s Nutrition
Center, Houston, TX, United States of America
| | - Alan R. Burns
- University of Houston, College of Optometry, Houston, TX,
United States of America,Baylor College of Medicine, Children’s Nutrition
Center, Houston, TX, United States of America
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8
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Espana EM, Birk DE. Composition, structure and function of the corneal stroma. Exp Eye Res 2020; 198:108137. [PMID: 32663498 PMCID: PMC7508887 DOI: 10.1016/j.exer.2020.108137] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 06/29/2020] [Accepted: 06/30/2020] [Indexed: 12/13/2022]
Abstract
No other tissue in the body depends more on the composition and organization of the extracellular matrix (ECM) for normal structure and function than the corneal stroma. The precise arrangement and orientation of collagen fibrils, lamellae and keratocytes that occurs during development and is needed in adults to maintain stromal function is dependent on the regulated interaction of multiple ECM components that contribute to attain the unique properties of the cornea: transparency, shape, mechanical strength, and avascularity. This review summarizes the contribution of different ECM components, their structure, regulation and function in modulating the properties of the corneal stroma. Fibril forming collagens (I, III, V), fibril associated collagens with interrupted triple helices (XII and XIV), network forming collagens (IV, VI and VIII) as well as small leucine-rich proteoglycans (SLRP) expressed in the stroma: decorin, biglycan, lumican, keratocan, and fibromodulin are some of the ECM components reviewed in this manuscript. There are spatial and temporal differences in the expression of these ECM components, as well as interactions among them that contribute to stromal function. Unique regions within the stroma like Bowman's layer and Descemet's layer are discussed. To define the complexity of corneal stroma composition and structure as well as the relationship to function is a daunting task. Our knowledge is expanding, and we expect that this review provides a comprehensive overview of current knowledge, definition of gaps and suggests future research directions.
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Affiliation(s)
- Edgar M Espana
- Department of Molecular Pharmacology and Physiology, USA; Cornea, External Disease and Refractive Surgery, Department of Ophthalmology, University of South Florida, Morsani College of Medicine, Tampa, FL, USA
| | - David E Birk
- Department of Molecular Pharmacology and Physiology, USA.
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9
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Feneck EM, Souza RB, Lewis PN, Hayes S, Pereira LV, Meek KM. Developmental abnormalities in the cornea of a mouse model for Marfan syndrome. Exp Eye Res 2020; 194:108001. [PMID: 32173378 PMCID: PMC7232021 DOI: 10.1016/j.exer.2020.108001] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 02/14/2020] [Accepted: 03/09/2020] [Indexed: 11/17/2022]
Abstract
Elastic fibres provide tissues with elasticity and flexibility. In the healthy human cornea, elastic fibres are limited to the posterior region of the peripheral stroma, but their specific functional role remains elusive. Here, we examine the physical and structural characteristics of the cornea during development in the mgΔloxPneo dominant-negative mouse model for Marfan syndrome, in which the physiological extracellular matrix of its elastic-fibre rich tissues is disrupted by the presence of a dysfunctional fibrillin-1 glycoprotein. Optical coherence tomography demonstrated a reduced corneal thickness in the mutant compared to wild type mice from embryonic day 16.5 until adulthood. X-ray scattering and electron microscopy revealed a disruption to both the elastic fibre and collagen fibril ultrastructure in the knockout mice, as well as abnormally low levels of the proteoglycan decorin. It is suggested that these alterations might be a result of increased transforming growth factor beta signalling. To conclude, this study has demonstrated corneal structure and ultrastructure to be altered when fibrillin-1 is disrupted and has provided insights into the role of fibrillin-1 in developing a functional cornea. mgΔloxPneo mice showed abnormalities in corneal thickness from embryonic development through to adulthood. Elastic fibres were evident from E16.5 in both the WT and mgΔloxPneo mouse corneas. Adult mgΔloxPneo mouse corneas exhibited a disorganised elastic fibre network with unusually high levels of branching. The disrupted collagen arrangement seen in adult mgΔloxPneo mice corneas is likely linked to lower levels of decorin in these corneas.
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Affiliation(s)
- Eleanor M Feneck
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Rodrigo B Souza
- Department of Genetics and Evolutionary Biology, University of Sᾶo Paulo, Rua do Matᾶo, Sᾶo Paulo, Brazil
| | - Philip N Lewis
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Sally Hayes
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Lygia V Pereira
- Department of Genetics and Evolutionary Biology, University of Sᾶo Paulo, Rua do Matᾶo, Sᾶo Paulo, Brazil
| | - Keith M Meek
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK.
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10
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Lewis PN, White TL, Feneck EM, Young RD, Meek KM. Elastin Content and Distribution in Endothelial Keratoplasty Tissue Determines Direction of Scrolling. Am J Ophthalmol 2019; 197:181-182. [PMID: 30297218 DOI: 10.1016/j.ajo.2018.08.047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 08/30/2018] [Indexed: 01/17/2023]
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11
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Aghaei-Ghareh-Bolagh B, Guan J, Wang Y, Martin AD, Dawson R, Mithieux SM, Weiss AS. Optically robust, highly permeable and elastic protein films that support dual cornea cell types. Biomaterials 2019; 188:50-62. [DOI: 10.1016/j.biomaterials.2018.10.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 09/26/2018] [Accepted: 10/07/2018] [Indexed: 10/28/2022]
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12
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Feneck EM, Lewis PN, Ralphs J, Meek KM. A comparative study of the elastic fibre system within the mouse and human cornea. Exp Eye Res 2018; 177:35-44. [PMID: 30053442 PMCID: PMC6280038 DOI: 10.1016/j.exer.2018.07.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 06/11/2018] [Accepted: 07/21/2018] [Indexed: 01/26/2023]
Abstract
The cornea relies on its organised extracellular matrix for maintaining transparency and biomechanical strength. Studies have identified an elastic fibre system within the human posterior cornea, thought to allow for slight deformations in response to internal pressure fluctuations within the eye. However, the type of elastic fibres that exist within the cornea and their roles remain elusive. The aim of this study was to compare the distribution and organisation of the elastic fibres within the posterior peripheral mouse and human cornea, and elucidate how these fibres integrate with the trabecular meshwork, whilst characterising the distribution of their main likely components (fibrillin-1, elastin and type VI collagen) in different parts of the cornea and adjacent sclera. We identified key differences in the elastic fibre system between the human and mouse cornea. True elastic fibres (containing elastin) were identified within the human posterior peripheral cornea. Elastic fibres appeared to present as an extensive network throughout the mouse corneal stroma, but as fibrillin-rich microfibril bundles rather than true elastic fibres. However, tropoelastin staining indicated the possibility that true elastic fibres had yet to develop in the young mice studied. Differences were also apparent within the anatomy of the trabecular meshwork. The human trabecular meshwork appeared to insert between the corneal stroma and Descemet's membrane, with elastic fibres continuing into the stroma from the trabecular meshwork anterior to Descemet's membrane. Within the mouse cornea, no clear insertion point of the trabecular meshwork was seen, instead the elastic fibres within the trabecular meshwork continued into Descemet's membrane, with the trabecular meshwork joining posterior to Descemet's membrane. True Elastic fibres (containing elastin) occur within the human posterior peripheral cornea. A fibrillin-rich microfibril system was found throughout the mouse corneal stroma, with no apparent true elastic fibres. Human trabecular meshwork inserts between the posterior corneal stroma and Descemet's membrane. A continuity of elastic fibres was identified between cornea and trabecular meshwork in both species.
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Affiliation(s)
- Eleanor M Feneck
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Philip N Lewis
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Jim Ralphs
- School of Biosciences, Cardiff University, Cathays Park, Cardiff, CF10 3AX, UK
| | - Keith M Meek
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK.
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13
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Cooke ME, Jones SW, Ter Horst B, Moiemen N, Snow M, Chouhan G, Hill LJ, Esmaeli M, Moakes RJA, Holton J, Nandra R, Williams RL, Smith AM, Grover LM. Structuring of Hydrogels across Multiple Length Scales for Biomedical Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1705013. [PMID: 29430770 DOI: 10.1002/adma.201705013] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2017] [Revised: 10/20/2017] [Indexed: 06/08/2023]
Abstract
The development of new materials for clinical use is limited by an onerous regulatory framework, which means that taking a completely new material into the clinic can make translation economically unfeasible. One way to get around this issue is to structure materials that are already approved by the regulator, such that they exhibit very distinct physical properties and can be used in a broader range of clinical applications. Here, the focus is on the structuring of soft materials at multiple length scales by modifying processing conditions. By applying shear to newly forming materials, it is possible to trigger molecular reorganization of polymer chains, such that they aggregate to form particles and ribbon-like structures. These structures then weakly interact at zero shear forming a solid-like material. The resulting self-healing network is of particular use for a range of different biomedical applications. How these materials are used to allow the delivery of therapeutic entities (cells and proteins) and as a support for additive layer manufacturing of larger-scale tissue constructs is discussed. This technology enables the development of a range of novel materials and structures for tissue augmentation and regeneration.
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Affiliation(s)
- Megan E Cooke
- School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Institute of Inflammation and Ageing, MRC Musculoskeletal Ageing Centre, QE Hospital, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Simon W Jones
- Institute of Inflammation and Ageing, MRC Musculoskeletal Ageing Centre, QE Hospital, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Britt Ter Horst
- School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Scar Free Foundation Centre for Burns Research, QE Hospital, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Naiem Moiemen
- Scar Free Foundation Centre for Burns Research, QE Hospital, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Martyn Snow
- School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Gurpreet Chouhan
- School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Lisa J Hill
- Institute of Inflammation and Ageing, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Maryam Esmaeli
- Institute of Inflammation and Ageing, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Richard J A Moakes
- School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - James Holton
- School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Rajpal Nandra
- School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Richard L Williams
- School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Alan M Smith
- Department of Pharmacy, University of Huddersfield, Queensgate, Huddersfield, HD1 3DH, UK
| | - Liam M Grover
- School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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14
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Grieve K, Ghoubay D, Georgeon C, Latour G, Nahas A, Plamann K, Crotti C, Bocheux R, Borderie M, Nguyen TM, Andreiuolo F, Schanne-Klein MC, Borderie V. Stromal striae: a new insight into corneal physiology and mechanics. Sci Rep 2017; 7:13584. [PMID: 29051516 PMCID: PMC5648881 DOI: 10.1038/s41598-017-13194-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 09/19/2017] [Indexed: 12/26/2022] Open
Abstract
We uncover the significance of a previously unappreciated structural feature in corneal stroma, important to its biomechanics. Vogt striae are a known clinical indicator of keratoconus, and consist of dark, vertical lines crossing the corneal depth. However we detected stromal striae in most corneas, not only keratoconus. We observed striae with multiple imaging modalities in 82% of 118 human corneas, with pathology-specific differences. Striae generally depart from anchor points at Descemet’s membrane in the posterior stroma obliquely in a V-shape, whereas in keratoconus, striae depart vertically from posterior toward anterior stroma. Optical coherence tomography shear wave elastography showed discontinuity of rigidity, and second harmonic generation and scanning electron microscopies showed undulation of lamellae at striae locations. Striae visibility decreased beyond physiological pressure and increased beyond physiological hydration. Immunohistology revealed striae to predominantly contain collagen VI, lumican and keratocan. The role of these regions of collagen VI linking sets of lamellae may be to absorb increases in intraocular pressure and external shocks.
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Affiliation(s)
- Kate Grieve
- CHNO des Quinze Vingts, INSERM-DHOS CIC 503, Paris, France. .,Institut de la Vision, Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Paris, France.
| | - Djida Ghoubay
- CHNO des Quinze Vingts, INSERM-DHOS CIC 503, Paris, France.,Institut de la Vision, Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Paris, France
| | | | - Gael Latour
- Laboratoire Imagerie et Modélisation en Neurobiologie et Cancérologie, Univ. Paris-Sud, CNRS, Université Paris-Saclay, Orsay, France
| | | | - Karsten Plamann
- ENSTA ParisTech, Ecole polytechnique, CNRS, Université Paris-Saclay, Palaiseau, France
| | - Caroline Crotti
- ENSTA ParisTech, Ecole polytechnique, CNRS, Université Paris-Saclay, Palaiseau, France
| | | | - Marie Borderie
- CHNO des Quinze Vingts, INSERM-DHOS CIC 503, Paris, France
| | | | | | - Marie-Claire Schanne-Klein
- Laboratoire d'Optique et Biosciences, Ecole polytechnique, CNRS, INSERM U1182,Université Paris-Saclay, Palaiseau, France
| | - Vincent Borderie
- CHNO des Quinze Vingts, INSERM-DHOS CIC 503, Paris, France.,Institut de la Vision, Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Paris, France
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15
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White TL, Lewis P, Hayes S, Fergusson J, Bell J, Farinha L, White NS, Pereira LV, Meek KM. The Structural Role of Elastic Fibers in the Cornea Investigated Using a Mouse Model for Marfan Syndrome. Invest Ophthalmol Vis Sci 2017; 58:2106-2116. [PMID: 28395026 PMCID: PMC5695733 DOI: 10.1167/iovs.16-21358] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Purpose The presence of fibrillin-rich elastic fibers in the cornea has been overlooked in recent years. The aim of the current study was to elucidate their functional role using a mouse model for Marfan syndrome, defective in fibrillin-1, the major structural component of the microfibril bundles that constitute most of the elastic fibers. Methods Mouse corneas were obtained from animals with a heterozygous fibrillin-1 mutation (Fbn1+/-) and compared to wild type controls. Corneal thickness and radius of curvature were calculated using optical coherence tomography microscopy. Elastic microfibril bundles were quantified and visualized in three-dimensions using serial block face scanning electron microscopy. Transmission electron microscopy was used to analyze stromal ultrastructure and proteoglycan distribution. Center-to-center average interfibrillar spacing was determined using x-ray scattering. Results Fbn1+/- corneas were significantly thinner than wild types and displayed a higher radius of curvature. In the Fbn1+/- corneas, elastic microfibril bundles were significantly reduced in density and disorganized compared to wild-type controls, in addition to containing a higher average center-to-center collagen interfibrillar spacing in the center of the cornea. No other differences were detected in stromal ultrastructure or proteoglycan distribution between the two groups. Proteoglycan side chains appeared to colocalize with the microfibril bundles. Conclusions Elastic fibers have an important, multifunctional role in the cornea as highlighted by the differences observed between Fbn1+/- and wild type animals. We contend that the presence of normal quantities of structurally organized elastic fibers are required to maintain the correct geometry of the cornea, which is disrupted in Marfan syndrome.
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Affiliation(s)
- Tomas L White
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, United Kingdom
| | - Philip Lewis
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, United Kingdom
| | - Sally Hayes
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, United Kingdom
| | - James Fergusson
- Vision Science Bioimaging Labs, School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - James Bell
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, United Kingdom
| | - Luis Farinha
- Department of Genetics and Evolutionary Biology, University of São Paulo, Rua do Matão, São Paulo, Brazil
| | - Nick S White
- Vision Science Bioimaging Labs, School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Lygia V Pereira
- Department of Genetics and Evolutionary Biology, University of São Paulo, Rua do Matão, São Paulo, Brazil
| | - Keith M Meek
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, United Kingdom
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16
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White TL, Lewis PN, Young RD, Kitazawa K, Inatomi T, Kinoshita S, Meek KM. Elastic microfibril distribution in the cornea: Differences between normal and keratoconic stroma. Exp Eye Res 2017; 159:40-48. [PMID: 28315339 PMCID: PMC5451143 DOI: 10.1016/j.exer.2017.03.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 02/15/2017] [Accepted: 03/12/2017] [Indexed: 11/28/2022]
Abstract
The optical and biomechanical properties of the cornea are largely governed by the collagen-rich stroma, a layer that represents approximately 90% of the total thickness. Within the stroma, the specific arrangement of superimposed lamellae provides the tissue with tensile strength, whilst the spatial arrangement of individual collagen fibrils within the lamellae confers transparency. In keratoconus, this precise stromal arrangement is lost, resulting in ectasia and visual impairment. In the normal cornea, we previously characterised the three-dimensional arrangement of an elastic fiber network spanning the posterior stroma from limbus-to-limbus. In the peripheral cornea/limbus there are elastin-containing sheets or broad fibers, most of which become microfibril bundles (MBs) with little or no elastin component when reaching the central cornea. The purpose of the current study was to compare this network with the elastic fiber distribution in post-surgical keratoconic corneal buttons, using serial block face scanning electron microscopy and transmission electron microscopy. We have demonstrated that the MB distribution is very different in keratoconus. MBs are absent from a region of stroma anterior to Descemet's membrane, an area that is densely populated in normal cornea, whilst being concentrated below the epithelium, an area in which they are absent in normal cornea. We contend that these latter microfibrils are produced as a biomechanical response to provide additional strength to the anterior stroma in order to prevent tissue rupture at the apex of the cone. A lack of MBs anterior to Descemet's membrane in keratoconus would alter the biomechanical properties of the tissue, potentially contributing to the pathogenesis of the disease.
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Affiliation(s)
- Tomas L White
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK
| | - Philip N Lewis
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK
| | - Robert D Young
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK
| | - Koji Kitazawa
- Department of Ophthalmology, Kyoto Prefectural University, Kyoto, Japan; Department of Frontier Medical Science and Technology for Ophthalmology, Kyoto Prefectural University, Kyoto, Japan
| | - Tsutomu Inatomi
- Department of Ophthalmology, Kyoto Prefectural University, Kyoto, Japan
| | - Shigeru Kinoshita
- Department of Frontier Medical Science and Technology for Ophthalmology, Kyoto Prefectural University, Kyoto, Japan
| | - Keith M Meek
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK.
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17
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Chakravarti S. Fibrillin Microfibrils Keep the Cornea in Shape. Invest Ophthalmol Vis Sci 2017; 58:2117. [PMID: 28395027 PMCID: PMC6108237 DOI: 10.1167/iovs.17-21840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Shukti Chakravarti
- Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States;
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18
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Ho LC, Sigal IA, Jan NJ, Yang X, van der Merwe Y, Yu Y, Chau Y, Leung CK, Conner IP, Jin T, Wu EX, Kim SG, Wollstein G, Schuman JS, Chan KC. Non-invasive MRI Assessments of Tissue Microstructures and Macromolecules in the Eye upon Biomechanical or Biochemical Modulation. Sci Rep 2016; 6:32080. [PMID: 27561353 PMCID: PMC5000015 DOI: 10.1038/srep32080] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 08/02/2016] [Indexed: 02/07/2023] Open
Abstract
The microstructural organization and composition of the corneoscleral shell (CSS) determine the biomechanical behavior of the eye, and are important in diseases such as glaucoma and myopia. However, limited techniques can assess these properties globally, non-invasively and quantitatively. In this study, we hypothesized that multi-modal magnetic resonance imaging (MRI) can reveal the effects of biomechanical or biochemical modulation on CSS. Upon intraocular pressure (IOP) elevation, CSS appeared hyperintense in both freshly prepared ovine eyes and living rat eyes using T2-weighted MRI. Quantitatively, transverse relaxation time (T2) of CSS increased non-linearly with IOP at 0-40 mmHg and remained longer than unloaded tissues after being unpressurized. IOP loading also increased fractional anisotropy of CSS in diffusion tensor MRI without apparent change in magnetization transfer MRI, suggestive of straightening of microstructural fibers without modification of macromolecular contents. Lastly, treatments with increasing glyceraldehyde (mimicking crosslinking conditions) and chondroitinase-ABC concentrations (mimicking glycosaminoglycan depletion) decreased diffusivities and increased magnetization transfer in cornea, whereas glyceraldehyde also increased magnetization transfer in sclera. In summary, we demonstrated the changing profiles of MRI contrast mechanisms resulting from biomechanical or biochemical modulation of the eye non-invasively. Multi-modal MRI may help evaluate the pathophysiological mechanisms in CSS and the efficacy of corneoscleral treatments.
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Affiliation(s)
- Leon C. Ho
- NeuroImaging Laboratory , University of Pittsburgh, Pittsburgh, PA, USA
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, China
| | - Ian A. Sigal
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, China
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ning-Jiun Jan
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Xiaoling Yang
- NeuroImaging Laboratory , University of Pittsburgh, Pittsburgh, PA, USA
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Yolandi van der Merwe
- NeuroImaging Laboratory , University of Pittsburgh, Pittsburgh, PA, USA
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, PA, USA
| | - Yu Yu
- Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Hong Kong, China
| | - Ying Chau
- Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Hong Kong, China
- Division of Biomedical Engineering, Hong Kong University of Science and Technology, Hong Kong, China
| | - Christopher K. Leung
- University Eye Center, Hong Kong Eye Hospital, Hong Kong, China
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Ian P. Conner
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tao Jin
- NeuroImaging Laboratory , University of Pittsburgh, Pittsburgh, PA, USA
| | - Ed X. Wu
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, China
| | - Seong-Gi Kim
- NeuroImaging Laboratory , University of Pittsburgh, Pittsburgh, PA, USA
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittsburgh, PA, USA
- Center for Neuroscience Imaging Research, Institute for Basic Science, Suwon, Korea
- Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Korea
| | - Gadi Wollstein
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, PA, USA
| | - Joel S. Schuman
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittsburgh, PA, USA
- Clinical and Translational Science Institute, University of Pittsburgh, Pittsburgh, PA, USA
| | - Kevin C. Chan
- NeuroImaging Laboratory , University of Pittsburgh, Pittsburgh, PA, USA
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, PA, USA
- Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittsburgh, PA, USA
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de Andrade FA, Fiorot SHS, Benchimol EI, Provenzano J, Martins VJ, Levy RA. The autoimmune diseases of the eyes. Autoimmun Rev 2016; 15:258-71. [DOI: 10.1016/j.autrev.2015.12.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 11/27/2015] [Indexed: 02/06/2023]
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20
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Xuan M, Wang S, Liu X, He Y, Li Y, Zhang Y. Proteins of the corneal stroma: importance in visual function. Cell Tissue Res 2016; 364:9-16. [DOI: 10.1007/s00441-016-2372-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 01/27/2016] [Indexed: 12/13/2022]
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Lewis PN, White TL, Young RD, Bell JS, Winlove CP, Meek KM. Three-dimensional arrangement of elastic fibers in the human corneal stroma. Exp Eye Res 2015; 146:43-53. [PMID: 26704458 PMCID: PMC4889784 DOI: 10.1016/j.exer.2015.12.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 12/09/2015] [Accepted: 12/10/2015] [Indexed: 01/26/2023]
Abstract
The cornea is the main refracting lens in the eye. As part of the outer tunic it has to be resilient, a property conferred by the organisation of the constituent collagen. It also has to be sufficiently elastic to regain its exact shape when deformed, in order not to distort the retinal image. The basis of this elasticity is not fully understood. The purpose of this study was to characterise in three dimensions the arrangement and distribution of elastic fibers in the human corneal stroma, using serial block face scanning electron microscopy. We have demonstrated that there exists a complex network of elastic fibers that appear to originate in the sclera or limbus. These appear as elastic sheets in the limbus and peripheral cornea immediately above the trabecular meshwork which itself appears to extend above Descemet's membrane in the peripheral stroma. From these sheets, elastic fibers extend into the cornea; moving centrally they bifurcate and trifurcate into narrower fibers and are concentrated in the posterior stroma immediately above Descemet's membrane. We contend that elastic sheets will play an important role in the biomechanical deformation and recovery of the peripheral cornea. The network may also have practical implications for understanding the structural basis behind a number of corneal surgeries. We have characterised a complex system of elastic fibers in the posterior cornea. These exist as sheets in the limbus that fenestrate and become fibers in the cornea. We believe these fibers provide the elastic restoring force in the peripheral tissue. This system should help explain some surgical properties of the cornea.
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Affiliation(s)
- Philip N Lewis
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK
| | - Tomas L White
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK
| | - Robert D Young
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK
| | - James S Bell
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK
| | - C Peter Winlove
- Department of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
| | - Keith M Meek
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK.
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Dua HS, Faraj LA, Said DG. Dua’s layer: discovery, characteristics, clinical applications, controversy and potential relevance to glaucoma. EXPERT REVIEW OF OPHTHALMOLOGY 2015. [DOI: 10.1586/17469899.2015.1103180] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Nanomedicine approaches for corneal diseases. J Funct Biomater 2015; 6:277-98. [PMID: 25941990 PMCID: PMC4493512 DOI: 10.3390/jfb6020277] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 04/28/2015] [Accepted: 04/28/2015] [Indexed: 02/04/2023] Open
Abstract
Corneal diseases are the third leading cause of blindness globally. Topical nonsteroidal anti-inflammatory drugs (NSAIDs), steroids, antibiotics and tissue transplantation are currently used to treat corneal pathological conditions. However, barrier properties of the ocular surface necessitate high concentration of the drugs applied in the eye repeatedly. This often results in poor efficacy and several side-effects. Nanoparticle-based molecular medicine seeks to overcome these limitations by enhancing the permeability and pharmacological properties of the drugs. The promise of nanomedicine approaches for treating corneal defects and restoring vision without side effects in preclinical animal studies has been demonstrated. Numerous polymeric, metallic and hybrid nanoparticles capable of transporting genes into desired corneal cells to intercept pathologic pathways and processes leading to blindness have been identified. This review provides an overview of corneal diseases, nanovector properties and their applications in drug-delivery and corneal disease management.
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