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A unique pre-endothelial layer at the posterior peripheral cornea: ultrastructural study. Sci Rep 2022; 12:2556. [PMID: 35169268 PMCID: PMC8847363 DOI: 10.1038/s41598-022-06552-6] [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: 04/23/2021] [Accepted: 01/21/2022] [Indexed: 11/20/2022] Open
Abstract
This study was conducted to investigate the ultrastructure of a unique structures at the anterior side of the endothelium of the posterior peripheral cornea and compare their inner fibers to those of the limbus and sclera. The unique structures at the anterior side of endothelium was referred as a pre-endothelial (PENL) structures in the present manuscript. Ten anonymous-donor human corneoscleral rims (leftover after corneal transplants) were processed for electron microscopy. Semi-thin sections were examined using an Olympus BX53 microscope, and ultrathin sections were studied using a JOEL 1400 transmission electron microscope. A unique PENL structures was identified at the posterior peripheral cornea at a radial distance of approximately 70–638 µm, from the endpoint of Descemet’s membrane. The PENL thinned out gradually and disappeared in the center. The contained an electron-dense sheath with periodic structures (narrow-spacing fibers), wide-spacing fibers, and numerous microfibrils. Typical elastic fibers were present in the sclera and limbus but were not observed in the PENL. This study revealed the existence of a new acellular PENL, containing unique fibrillar structures that were unseen in the corneal stroma. From the evidence describe in this paper we therefore suggest that PENL is a distinct morphological structure present at the corneal periphery.
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Kelly SJ, duPlessis L, Soley J, Noble F, Wells HC, Kelly PJ. Pilot study on the effects of preservatives on corneal collagen parameters measured by small angle X-ray scattering analysis. BMC Res Notes 2021; 14:78. [PMID: 33640024 PMCID: PMC7913446 DOI: 10.1186/s13104-021-05494-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 02/16/2021] [Indexed: 11/30/2022] Open
Abstract
Objective Small angle X-ray scattering (SAXS) analysis is a sensitive way of determining the ultrastructure of collagen in tissues. Little is known about how parameters measured by SAXS are affected by preservatives commonly used to prevent autolysis. We determined the effects of formalin, glutaraldehyde, Triton X and saline on measurements of fibril diameter, fibril diameter distribution, and D-spacing of corneal collagen using SAXS analysis. Results Compared to sections of sheep and cats’ corneas stored frozen as controls, those preserved in 5% glutaraldehyde and 10% formalin had significantly larger mean collagen fibril diameters, increased fibril diameter distribution and decreased D-spacing. Sections of corneas preserved in Triton X had significantly increased collagen fibril diameters and decreased fibril diameter distribution. Those preserved in 0.9% saline had significantly increased mean collagen fibril diameters and decreased diameter distributions. Subjectively, the corneas preserved in 5% glutaraldehyde and 10% formalin maintained their transparency but those in Triton X and 0.9% saline became opaque. Subjective morphological assessment of transmission electron microscope images of corneas supported the SAXS data. Workers using SAXS analysis to characterize collagen should be alerted to changes that can be introduced by common preservatives in which their samples may have been stored.
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Affiliation(s)
- Susyn Joan Kelly
- Department of Clinical Sciences, Ross University of Veterinary Medicine, Basseterre, Saint Kitts and Nevis. .,School of Engineering and Advanced Technology, Massey University, Palmerston North, 4442, New Zealand.
| | - Lizette duPlessis
- Department of Anatomy and Physiology, Electron Microscope Unit, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, 0110, South Africa
| | - John Soley
- Department of Anatomy and Physiology, Electron Microscope Unit, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, 0110, South Africa
| | - Frazer Noble
- School of Engineering and Advanced Technology, Massey University, Palmerston North, 4442, New Zealand
| | - Hannah Carolyn Wells
- School of Engineering and Advanced Technology, Massey University, Palmerston North, 4442, New Zealand
| | - Patrick John Kelly
- Department of Clinical Sciences, Ross University of Veterinary Medicine, Basseterre, Saint Kitts and Nevis
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Tonniges JR, Albert B, Calomeni EP, Roy S, Lee J, Mo X, Cole SE, Agarwal G. Collagen Fibril Ultrastructure in Mice Lacking Discoidin Domain Receptor 1. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2016; 22:599-611. [PMID: 27329311 PMCID: PMC5174982 DOI: 10.1017/s1431927616000787] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The quantity and quality of collagen fibrils in the extracellular matrix (ECM) have a pivotal role in dictating biological processes. Several collagen-binding proteins (CBPs) are known to modulate collagen deposition and fibril diameter. However, limited studies exist on alterations in the fibril ultrastructure by CBPs. In this study, we elucidate how the collagen receptor, discoidin domain receptor 1 (DDR1) regulates the collagen content and ultrastructure in the adventitia of DDR1 knock-out (KO) mice. DDR1 KO mice exhibit increased collagen deposition as observed using Masson's trichrome. Collagen ultrastructure was evaluated in situ using transmission electron microscopy, scanning electron microscopy, and atomic force microscopy. Although the mean fibril diameter was not significantly different, DDR1 KO mice had a higher percentage of fibrils with larger diameter compared with their wild-type littermates. No significant differences were observed in the length of D-periods. In addition, collagen fibrils from DDR1 KO mice exhibited a small, but statistically significant, increase in the depth of the fibril D-periods. Consistent with these observations, a reduction in the depth of D-periods was observed in collagen fibrils reconstituted with recombinant DDR1-Fc. Our results elucidate how DDR1 modulates collagen fibril ultrastructure in vivo, which may have important consequences in the functional role(s) of the underlying ECM.
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Affiliation(s)
- Jeffrey R. Tonniges
- Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Benjamin Albert
- Biomedical Engineering Department, The Ohio State University, Columbus, OH 43210, USA
| | - Edward P. Calomeni
- Department of Pathology, The Ohio State University, Columbus, OH 43210, USA
| | - Shuvro Roy
- David Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Joan Lee
- David Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Xiaokui Mo
- Center for Biostatistics, The Ohio State University, Columbus, OH 43210, USA
| | - Susan E. Cole
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - Gunjan Agarwal
- Biomedical Engineering Department, The Ohio State University, Columbus, OH 43210, USA
- David Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
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Gronkiewicz KM, Giuliano EA, Kuroki K, Bunyak F, Sharma A, Teixeira LBC, Hamm CW, Mohan RR. Development of a novel in vivo corneal fibrosis model in the dog. Exp Eye Res 2015; 143:75-88. [PMID: 26450656 DOI: 10.1016/j.exer.2015.09.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 09/09/2015] [Accepted: 09/16/2015] [Indexed: 12/11/2022]
Abstract
The aim of this study was to develop a novel in vivo corneal model of fibrosis in dogs utilizing alkali burn and determine the ability of suberanilohydroxamic acid (SAHA) to inhibit corneal fibrosis using this large animal model. To accomplish this, we used seven research Beagle dogs. An axial corneal alkali burn in dogs was created using 1 N NaOH topically. Six dogs were randomly and equally assigned into 2 groups: A) vehicle (DMSO, 2 μL/mL); B) anti-fibrotic treatment (50 μM SAHA). The degree of corneal opacity, ocular health, and anti-fibrotic effects of SAHA were determined utilizing the Fantes grading scale, modified McDonald-Shadduck (mMS) scoring system, optical coherence tomography (OCT), corneal histopathology, immunohistochemistry (IHC), and transmission electron microscopy (TEM). The used alkali burn dose to produce corneal fibrosis was well tolerated as no significant difference in mMS scores between control and treatment groups (p = 0.89) were detected. The corneas of alkali burned dogs showed significantly greater levels of α-smooth muscle actin, the fibrotic marker, than the controls (p = 0.018). Total corneal thickness of all dogs post-burn was significantly greater than baseline OCT images irrespective of treatment (p = 0.004); TEM showed that alkali burned corneas had significantly greater minimum and maximum interfibrillar distances than the controls (p = 0.026, p = 0.018). The tested topical corneal alkali burn dose generated significant opacity and fibrosis in dog corneas without damaging the limbus as evidenced by histopathology, IHC, TEM, and OCT findings, and represents a viable large animal corneal fibrosis in vivo model. Additional in vivo SAHA dosing studies with larger sample size are warranted.
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Affiliation(s)
- K M Gronkiewicz
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, Columbia, MO, USA; Harry S. Truman Memorial Veteran Hospital, Columbia, MO, USA
| | - E A Giuliano
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, Columbia, MO, USA; Harry S. Truman Memorial Veteran Hospital, Columbia, MO, USA
| | - K Kuroki
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Columbia, MO, USA
| | - F Bunyak
- Department of Computer Science, University of Missouri, Columbia, MO, USA
| | - A Sharma
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, Columbia, MO, USA; Harry S. Truman Memorial Veteran Hospital, Columbia, MO, USA
| | - L B C Teixeira
- Department of Pathological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, WI, USA
| | - C W Hamm
- Mason Eye Institute, University of Missouri, Columbia, MO, USA
| | - R R Mohan
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, Columbia, MO, USA; Harry S. Truman Memorial Veteran Hospital, Columbia, MO, USA; Mason Eye Institute, University of Missouri, Columbia, MO, USA.
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Wells HC, Edmonds RL, Kirby N, Hawley A, Mudie ST, Haverkamp RG. Collagen fibril diameter and leather strength. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:11524-11531. [PMID: 24199635 DOI: 10.1021/jf4041854] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The main structural component of leather and skin is type I collagen in the form of strong fibrils. Strength is an important property of leather, and the way in which collagen contributes to the strength is not fully understood. Synchrotron-based small angle X-ray scattering (SAXS) is used to measure the collagen fibril diameter of leather from a range of animals, including sheep and cattle, that had a range of tear strengths. SAXS data were fit to a cylinder model. The collagen fibril diameter and tear strength were found to be correlated in bovine leather (r(2) = 0.59; P = 0.009), with stronger leather having thicker fibrils. There was no correlation between orientation index, i.e., fibril alignment, and fibril diameter for this data set. Ovine leather showed no correlation between tear strength and fibril diameter, nor was there a correlation across a selection of other animal leathers. The findings presented here suggest that there may be a different structural motif in skin compared with tendon, particularly ovine skin or leather, in which the diameter of the individual fibrils contributes less to strength than fibril alignment does.
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Affiliation(s)
- Hannah C Wells
- School of Engineering and Advanced Technology, Massey University , Private Bag 11222, Palmerston North, New Zealand 4442
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Keeping an eye on decellularized corneas: a review of methods, characterization and applications. J Funct Biomater 2013; 4:114-61. [PMID: 24956084 PMCID: PMC4030906 DOI: 10.3390/jfb4030114] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 05/08/2013] [Accepted: 05/28/2013] [Indexed: 12/13/2022] Open
Abstract
The worldwide limited availability of suitable corneal donor tissue has led to the development of alternatives, including keratoprostheses (Kpros) and tissue engineered (TE) constructs. Despite advances in bioscaffold design, there is yet to be a corneal equivalent that effectively mimics both the native tissue ultrastructure and biomechanical properties. Human decellularized corneas (DCs) could offer a safe, sustainable source of corneal tissue, increasing the donor pool and potentially reducing the risk of immune rejection after corneal graft surgery. Appropriate, human-specific, decellularization techniques and high-resolution, non-destructive analysis systems are required to ensure reproducible outputs can be achieved. If robust treatment and characterization processes can be developed, DCs could offer a supplement to the donor corneal pool, alongside superior cell culture systems for pharmacology, toxicology and drug discovery studies.
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