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McHugh KJ, Saint-Geniez M, Tao SL. Topographical control of ocular cell types for tissue engineering. J Biomed Mater Res B Appl Biomater 2013; 101:1571-84. [PMID: 23744715 PMCID: PMC4090092 DOI: 10.1002/jbm.b.32968] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2012] [Revised: 03/19/2013] [Accepted: 04/21/2013] [Indexed: 02/06/2023]
Abstract
Visual impairment affects over 285 million people worldwide and has a major impact on an individual's quality of life. Tissue engineering has the potential to increase the quality of life for many of these patients by preventing vision loss or restoring vision using cell-based therapies. However, these strategies will require an understanding of the microenvironmental factors that influence cell behavior. The eye is a well-organized organ whose structural complexity is essential for proper function. Interactions between ocular cells and their highly ordered extracellular matrix are necessary for maintaining key tissue properties including corneal transparency and retinal lamination. Therefore, it is not surprising that culturing these cells in vitro on traditional flat substrates result in irregular morphology. Instead, topographically patterned biomaterials better mimic native extracellular matrix and have been shown to elicit in vivo-like morphology and gene expression which is essential for tissue engineering. Herein we review multiple methods for producing well-controlled topography and discuss optimal biomaterial scaffold design for cells of the cornea, retina, and lens.
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Affiliation(s)
- Kevin J. McHugh
- The Charles Stark Draper Laboratory, Cambridge, MA
- Schepens Eye Research Institute, Boston, MA
- Department of Biomedical Engineering, Boston University, Boston, MA
| | - Magali Saint-Geniez
- Schepens Eye Research Institute, Boston, MA
- Department of Ophthalmology, Harvard Medical School, Boston, MA
| | - Sarah L. Tao
- The Charles Stark Draper Laboratory, Cambridge, MA
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Chaurasia SS, Champakalakshmi R, Li A, Poh R, Tan XW, Lakshminarayanan R, Lim CT, Tan DT, Mehta JS. Effect of fibrin glue on the biomechanical properties of human Descemet's membrane. PLoS One 2012; 7:e37456. [PMID: 22662156 PMCID: PMC3360777 DOI: 10.1371/journal.pone.0037456] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 04/21/2012] [Indexed: 01/06/2023] Open
Abstract
Background Corneal transplantation has rapidly evolved from full-thickness penetrating keratoplasty (PK) to selective tissue corneal transplantation, where only the diseased portions of the patient's corneal tissue are replaced with healthy donor tissue. Descemet's membrane endothelial keratoplasty (DMEK) performed in patients with corneal endothelial dysfunction is one such example where only a single layer of endothelial cells with its basement membrane (10–15 µm in thickness), Descemet's membrane (DM) is replaced. It is challenging to replace this membrane due to its intrinsic property to roll in an aqueous environment. The main objective of this study was to determine the effects of fibrin glue (FG) on the biomechanical properties of DM using atomic force microscopy (AFM) and relates these properties to membrane folding propensity. Methodology/Principal Findings Fibrin glue was sprayed using the EasySpray applicator system, and the biomechanical properties of human DM were determined by AFM. We studied the changes in the “rolling up” tendency of DM by examining the changes in the elasticity and flexural rigidity after the application of FG. Surface topography was assessed using scanning electron microscopy (SEM) and AFM imaging. Treatment with FG not only stabilized and stiffened DM but also led to a significant increase in hysteresis of the glue-treated membrane. In addition, flexural or bending rigidity values also increased in FG-treated membranes. Conclusions/Significance Our results suggest that fibrin glue provides rigidity to the DM/endothelial cell complex that may aid in subsequent manipulation by maintaining tissue integrity.
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Affiliation(s)
- Shyam S. Chaurasia
- Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore, Singapore
| | - Ravi Champakalakshmi
- Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore, Singapore
| | - Ang Li
- Department of Bioengineering and Department of Mechanical Engineering, National University of Singapore, Singapore, Singapore
| | - Rebekah Poh
- Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore, Singapore
| | - Xiao Wei Tan
- Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore, Singapore
| | | | - Chwee T. Lim
- Department of Bioengineering and Department of Mechanical Engineering, National University of Singapore, Singapore, Singapore
- Mechanobiology Institute, Singapore, Singapore
| | - Donald T. Tan
- Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore, Singapore
- Singapore National Eye Centre, Singapore, Singapore
| | - Jodhbir S. Mehta
- Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore, Singapore
- Singapore National Eye Centre, Singapore, Singapore
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Department of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore, Singapore
- * E-mail:
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Princz M, Sheardown H. Heparin-modified dendrimer crosslinked collagen matrices for the delivery of heparin-binding epidermal growth factor. J Biomed Mater Res A 2012; 100:1929-37. [DOI: 10.1002/jbm.a.34128] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Revised: 02/06/2012] [Accepted: 02/07/2012] [Indexed: 01/23/2023]
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Abstract
Although constantly exposed to the environment and "foreign bodies" such as contact lenses and unwashed fingertips, the ocular surface succumbs to infection relatively infrequently. This is, in large part, due to a very active and robust innate immune response mounted at the ocular surface. Studies over the past 20 years have revealed that small peptides with antimicrobial activity are a major component of the human innate immune response system. The ocular surface is no exception, with peptides of the defensin and cathelicidin families being detected in the tear film and secreted by corneal and conjunctival epithelial cells. There is also much evidence to suggest that the role of some antimicrobial peptides is not restricted to direct killing of pathogens, but, rather, that they function in various aspects of the immune response, including recruitment of immune cells, and through actions on dendritic cells provide a link to adaptive immunity. A role in wound healing is also supported. In this article, the properties, mechanisms of actions and functional roles of antimicrobial peptides are reviewed, with particular emphasis on the potential multifunctional roles of defensins and LL-37 (the only known human cathelicidin) at the ocular surface.
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Affiliation(s)
- Alison M McDermott
- University of Houston, College of Optometry, Houston, Texas 77204-2020, USA.
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Bentley E, Murphy CJ. Topical therapeutic agents that modulate corneal wound healing. Vet Clin North Am Small Anim Pract 2004; 34:623-38. [PMID: 15110975 DOI: 10.1016/j.cvsm.2003.12.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In summary, corneal wound healing is a complex phenomenon that involves interplay between the cellular elements of the cornea, numerous soluble factors, and the constituents of the ECM. Unfortunately, many studies that demonstrate marked alteration on cell behavior in vitro and even in in vivo experiments are often not helpful in the diseased patient, as shown by the results of careful clinical trials. Future work that addresses the complex milieu of the corneal wound healing environment by addressing the interaction of many of these factors will be more likely to be successful than seeking a single agent that will enhance wound healing in all situations. Modulation of wound healing processes by the application of topical therapeutic agents is, however, an expanding field of study sure to produce clinically significant improvements in the management of veterinary patients with corneal defects. The judicious use of topical cytoactive compounds has a place in the clinician's armamentarium integrated into a therapeutic plan that decreases the mechanical stresses imposed on the wound bed as well as removal of any underlying inciting cause.
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Affiliation(s)
- Ellison Bentley
- Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin, 2015 Linden Drive, Madison 53706, USA.
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Duncan G, Wormstone IM. Calcium cell signalling and cataract: role of the endoplasmic reticulum. Eye (Lond) 1999; 13 ( Pt 3b):480-3. [PMID: 10627828 DOI: 10.1038/eye.1999.125] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The lens possesses an impressive array of G-protein receptors that are coupled to the release of intracellular calcium. They include members of the muscarinic, adrenergic and purinergic families and activation of the former has been implicated in cataract for some time. There are several possible mechanisms whereby activation of such receptors could give rise to cataract. A prolonged increase in intracellular calcium would be expected to activate proteases such as calpain and so could induce unscheduled and irreversible breakdown of important structural proteins. It has recently been shown that activation of G-protein receptors also modulates lens cell growth, and any interference with the highly controlled pattern of cell growth and development within the lens is also likely to have catastrophic consequences. If the calcium store is totally inactivated in lens cells, for example by exposure to thapsigargin, then growth ceases. This finding provides a means of inhibiting the lens cell growth which leads to posterior capsular opacification (PCO). For example, it has been shown that thapsigargin-coated intraocular lenses totally inhibit lens cell growth within cultured capsular bags, and if this technology could be transferred to the clinic then it could provide a simple and relatively inexpensive means of preventing PCO.
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Affiliation(s)
- G Duncan
- School of Biological Sciences, University of East Anglia, Norwich, UK
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Klok EJ, Lubsen NH, Chamberlain CG, McAvoy JW. Induction and maintenance of differentiation of rat lens epithelium by FGF-2, insulin and IGF-1. Exp Eye Res 1998; 67:425-31. [PMID: 9820790 DOI: 10.1006/exer.1998.0534] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The differentiation of rat lens epithelial cells to fibre cells can be mimicked using lens epithelial explants, which differentiate in vitro when exposed to fibroblast growth factor (FGF). A previous study demonstrated that FGF is required only for initiation of differentiation: once induced by FGF, differentiation can be maintained by insulin (as assessed by following the accumulation of fibre-cell specific crystallins). The aim of this investigation was to determine whether insulin-like growth factor 1 (IGF-1) can also maintain differentiation and to include a cellular analysis of explants undergoing insulin-or IGF-maintained differentiation in vitro. Measurement of the accumulation of alpha-, beta- and gamma-crystallins showed that IGF-1, like insulin, can replace FGF-2 in directing the pulses of alpha-, beta- and gamma-crystallin gene expression once differentiation is initiated by FGF-2. Cells in both the peripheral and the central region of the explants responded. Immunolocalization of alpha, beta- and gamma-crystallins in these explants showed that a 15 min pulse of FGF-2 triggered the differentiation of only a few cells, whereas a 12 hr pulse primed virtually all the cells for differentiation. This indicates that in explants, individual cells differ in the rate at which they can respond to FGF-2.
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Affiliation(s)
- E j Klok
- Department of Anatomy, Histology and Institute for Biomedical Research (F13), The University of Sydney, Sydney, NSW, 2006, Australia
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Chamberlain CG, McAvoy JW. Fibre differentiation and polarity in the mammalian lens: a key role for FGF. Prog Retin Eye Res 1997. [DOI: 10.1016/s1350-9462(96)00034-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Blanquet PR, Croquet F. Activation of phosphotyrosine phosphatase activity is associated with decreased differentiation in adult bovine lens. J Cell Physiol 1995; 165:358-66. [PMID: 7593214 DOI: 10.1002/jcp.1041650217] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The postnatal vertebrate eye lens provides an opportunity to study possible involvement of reversible protein phosphorylation in the differentiation process of epithelial cells. Epithelial cells at the lens equator, indeed, differentiate continuously into fiber cells throughout life but this capacity progressively decreases with age. Here we describe the characterization of a phosphotyrosine-protein phosphatase(s) (PTPase(s)) in the equatorial epithelium of bovine lens which exhibits a high level of specific activity. PTPase(s) is detected in cellular detergent extracts using phospholabeled synthetic peptides, p-nitrophenyl phosphate, and lens epithelial membranes as substrates. We show that activity of this PTPase(s) is increased in the equatorial epithelium as the age is increased. We also show that this enzyme(s) exerts its dephosphorylating activity predominantly on a calpactin-like protein associated with lens epithelial membranes. Dephosphorylation of this protein is only obtained when membranes are subjected to extracts in the presence of fibroblast growth factor (FGF). It is suggested that an FGF-activated PTPase(s) might conceivably counteract effects of differentiation stimulatory factors for limiting differentiation of lens throughout life.
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Affiliation(s)
- P R Blanquet
- Unité de Recherches Gérontologiques, INSERM U118, affiliée CNRS, Association Claude Bernard, Paris, France
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