1
|
Tinasi ALSN, Silveira CPB, Honsho CS, Laus JL, Aldrovani M. Birefringence analysis of collagen supraorganization in cat corneas with tropical keratopathy. Vet Ophthalmol 2023; 26:398-406. [PMID: 37335898 DOI: 10.1111/vop.13124] [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: 02/06/2023] [Revised: 04/02/2023] [Accepted: 06/10/2023] [Indexed: 06/21/2023]
Abstract
OBJECTIVE To evaluate the birefringent properties of the cornea and examine the supraorganizational aspects of collagen fibers in cats with tropical keratopathy. PROCEDURE In this study, 10-micrometer-thick sections of corneal tissue from cats with tropical keratopathy were examined, both in the opaque and transparent areas of the anterior stroma. Control samples were obtained from healthy cat corneas. Polarized light microscopy was employed to evaluate the birefringent properties using two distinct methods. The first method involved measuring the optical retardation associated with corneal birefringence, while the second method assessed the alignment/waviness of the birefringent collagen fibers. Differences were significant when p < .05. RESULTS Tropical keratopathy resulted in a significant rise (p < .05) in optical retardation in both opaque and transparent regions of the cat cornea. In the anterior stroma, both the opaque zones and transparent tissue exhibited a higher degree of collagen fiber packing than the control corneas. However, no significant differences (p > .05) in alignment were observed between the transparent tissue of the diseased cornea and the healthy corneas. CONCLUSION Supraorganizational changes in collagen fiber packing are not restricted to lesion zones in cat corneas affected by tropical keratopathy. Such alterations also occur in the corneal tissue of the anterior stroma adjoining the lesions. Therefore, it is plausible that the transparent tissue of the anterior stroma in corneas affected by the disease may have functional abnormalities, despite its macroscopic healthy appearance. Additional investigations are required to clarify the implications of these potential defects and their conceivable contribution to tropical keratopathy.
Collapse
|
2
|
Gao J, Guo Z, Zhang Y, Liu Y, Xing F, Wang J, Luo X, Kong Y, Zhang G. Age-related changes in the ratio of Type I/III collagen and fibril diameter in mouse skin. Regen Biomater 2022; 10:rbac110. [PMID: 36683742 PMCID: PMC9847517 DOI: 10.1093/rb/rbac110] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 12/04/2022] [Accepted: 12/16/2022] [Indexed: 12/31/2022] Open
Abstract
The content of type I collagen (COL-I) and type III collagen (COL-III) and the ratio between them not only affect the skin elasticity and mechanical strength, but also determine the fibril diameter. In this research, we investigated the age-related changes in COL-I/COL-III ratio with their formed fibril diameter. The experimental result was obtained from high performance liquid chromatography-mass spectrometer, hydroxyproline determination, picrosirius red staining and transmission electron microscopes (TEM), respectively. The result indicated that the COL-I/COL-III ratio in mouse skin increased with aging. From the 0th to 9th week, the COL-I/COLIII ratio increased from 1.3:1 to 4.5:1. From the 9th to the 18th week, it remained between 4.5:1 and 4.9:1. The total content of COL-I and COL-III firstly increased and then decreased with aging. The TEM result showed that the fibril diameter increased with aging. From the 0th to 9th week, the average fibril diameter increased from 40 to 112 nm; From the 9th to 18th weeks, it increased from 112 to 140 nm. After the 9th week. The fibril diameter showed obvious uneven distribution. Thus, the COL-I/COLIII ratio was proportional to the fibril diameter, but inversely proportional to the uniformity of fibril diameter.
Collapse
Affiliation(s)
- Jianping Gao
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China,School of Chemical and Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhenhu Guo
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China,School of Chemical and Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yang Zhang
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Yuying Liu
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China,School of Chemical and Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fangyu Xing
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Junjie Wang
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Xi Luo
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China,School of Chemical and Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yingjun Kong
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China,School of Chemical and Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guifeng Zhang
- Correspondence address. Tel: +86 010 82613421, E-mail:
| |
Collapse
|
3
|
Doughty MJ. Averaged spacing and 2-d organization of collagen fibrils in the posterior cornea of the rabbit eye assessed by transmission electron microscopy. Curr Eye Res 2013; 39:329-39. [PMID: 23841461 DOI: 10.3109/02713683.2013.809767] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To assess how reproducible collagen fibril spacing might be in the corneal stroma as viewed by transmission electron microscopy by calculating averaged values for the 2-D organization. METHODS One cornea from 8 albino rabbits (2 kg) was fixed in situ to preserve natural shape. Thin sections were stained with 2% phosphotungstic acid (PTA) and images taken of fibrils from the central-posterior stroma. After projection at 250,000 X magnification, an overlay was prepared of the fibrils. Using a 500 × 500 nm region of interest (ROI), the distances to all fibril centers were measured to 2 nm resolution. RESULTS The sets of fibrils had average diameters between 32.4 and 36.1 nm (group mean ± SD of 34.4 ± 4.2 nm). The mean fibril density was 396 ± 21 per square micrometer, with a fibril area fraction of 38.7 ± 3.9%. The mean distance to the literal nearest neighbor fibril center was 43.2 ± 4.5 nm. A radial distribution analysis showed a distinct nearest neighbors peak at 51 nm. This nearest neighbors peak had an average amplitude of 2.236 ± 0.315, with a broader secondary peak being evident in all data sets centered at 93 nm with an average amplitude of 1.166 ± 0.093 (or 53.3 ± 7.1% of the nearest neighbors peak). CONCLUSIONS Overall, these results show that a predictable 2-D organization can be demonstrated for collagen fibrils in rabbit corneas when consideration is given to sample selection and preparation and the image analysis strategy.
Collapse
Affiliation(s)
- Michael J Doughty
- Department of Vision Sciences, Glasgow-Caledonian University , Glasgow , Scotland
| |
Collapse
|
4
|
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.
Collapse
|
6
|
Abstract
To investigate the extracellular matrices in the primo-nodes (PNs) and vessels (PVs) (Bonghan corpuscles and ducts), fine structure of the fibers comprising the extracellular matrices was studied in relation to the diameter and the periodicity to identify the types of the fibers. Electron micrographs of the fibers from the previously published works on the PNs and PVs were analyzed by using MATLAB programming and ImageJ software. The extracellular fibrous components of the PNs and PVs could be classified generally into two groups--thin collagen fibrils and thick non-collagenous wavy bent fibers. The thick bent fibers were fibrin-like. The diameters of the thick bent fibers were 30-200 nm and they were highly bent. This group included organ surface PNs and lymphatic PNs/PVs. The diameters of the collagen fibrils were 30-70 nm. Organ surface, heart, and hypodermis PVs were categorized in this group. The periodicity of bent fibers in an organ surface PN was 16.1 +/- 0.2 (SE) nm, and the periodicity of collagen fibrils in the hypodermis PVs was 37.4 +/- 0.5 (SE) nm. Further investigations are required to reveal the physiological implications of the two types of fibers in the PNs and PVs.
Collapse
Affiliation(s)
- Jong Hyun Jung
- Biomedical Physics Laboratory, Department of Physics and Astronomy, Seoul National University, Seoul, Korea.
| | | | | |
Collapse
|
8
|
Doughty MJ, Bergmanson JPG. Use of a Corneal Stroma Perfusion Technique and Transmission Electron Microscopy to Assess Ultrastructural Changes Associated with Exposure to Slightly Acidic pH 5.75 Solutions. Curr Eye Res 2009; 33:45-57. [DOI: 10.1080/02713680701805742] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
9
|
Doughty MJ, Bergmanson JPG. Assessment of the apparent intra- and inter-sample variability in the collagen fibril diameter in the posterior corneal stroma of rabbits. A transmission electron microscopy study. Ophthalmic Res 2006; 38:335-42. [PMID: 17047410 DOI: 10.1159/000096228] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Accepted: 07/27/2006] [Indexed: 11/19/2022]
Abstract
PURPOSE To assess the natural variability in the diameter of small collagen fibrils in the lamellae of corneal stroma of healthy young rabbits. MATERIALS AND METHODS The corneas of 6 young adult female New Zealand White rabbits (2.1 kg) were prepared for transmission electron microscopy (TEM) by fixation with a cacodylate-buffered 2% glutaraldehyde (pH 7.2-7.4, 320-340 mosm/kg). The corneas were embedded in Epon-Araldite, thin sections prepared from the central region of the posterior corneal stroma and stained with acidic uranyl acetate followed by acidic lead citrate. High magnification (x 33,000) micrographs were taken, and fibril diameters (FDs) measured at a final magnification of x 275,000 to a resolution of 2 nm. RESULTS Assessment of sampling-related errors indicated that the average diameter of the fibrils within any particular micrograph could be estimated to within 1% or better by measures of 100 fibrils. Assessments of the intra-sample variance (6 micrographs taken from the same cornea) indicated a group mean FD of 32.4 +/- 3.6 nm, whilst the inter-sample variance (6 micrographs taken from 6 different corneas) yielded an average of 33.1 +/- 4.5 nm (n = 100 fibrils/micrograph, +/-SD). However, group-averaged data sets of FDs, while unimodal, were not normally distributed, and cumulative averaging indicated a fixed range of FDs across the data sets. CONCLUSIONS Intra- and inter-sample variability in collagen FDs is very similar, but the analysis indicates that the collagen fibrils are not homogeneous and that closely adjacent lamellae can have subtle differences in average FD.
Collapse
Affiliation(s)
- Michael J Doughty
- Texas Eye Research and Technology Center, University of Houston College of Optometry, University of Houston, Houston, TX 77204-2020, USA
| | | |
Collapse
|
10
|
Abstract
This paper presents a numerical study on the transport of ions and ionic solution in human corneas and the corresponding influences on corneal hydration. The transport equations for each ionic species and ionic solution within the corneal stroma are derived based on the transport processes developed for electrolytic solutions, whereas the transport across epithelial and endothelial membranes is modelled by using phenomenological equations derived from the thermodynamics of irreversible processes. Numerical examples are provided for both human and rabbit corneas, from which some important features are highlighted.
Collapse
Affiliation(s)
- Long-yuan Li
- School of Engineering and Applied Science, Aston University, Birmingham B4 7ET, UK.
| | | |
Collapse
|