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Oh SE, Kim JH, Shin HJ, Kim SA, Park CK, Park HYL. Angiotensin II-Related Activation of Scleral Fibroblasts and Their Role on Retinal Ganglion Cell Death in Glaucoma. Pharmaceuticals (Basel) 2023; 16:ph16040556. [PMID: 37111313 PMCID: PMC10142824 DOI: 10.3390/ph16040556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 03/31/2023] [Accepted: 04/05/2023] [Indexed: 04/08/2023] Open
Abstract
We identify the angiotensin II (AngII)-associated changes in the extracellular matrix (ECM) and the biomechanical properties of the sclera after systemic hypotension. Systemic hypotension was induced by administering oral hydrochlorothiazide. AngII receptor levels and ECM components in the sclera and biomechanical properties were evaluated based on the stress–strain relationship after systemic hypotension. The effect of inhibiting the AngII receptor with losartan was determined in the systemic hypotensive animal model and the cultured scleral fibroblasts from this model. The effect of losartan on retinal ganglion cell (RGC) death was evaluated in the retina. Both AngII receptor type I (AT-1R) and type II (AT-2R) increased in the sclera after systemic hypotension. Proteins related to the activation of fibroblasts (transforming growth factor [TGF]-β1 and TGF-β2) indicated that transformation to myofibroblasts (α smooth muscle actin [SMA]), and the major ECM protein (collagen type I) increased in the sclera after systemic hypotension. These changes were associated with stiffening of the sclera in the biomechanical analysis. Administering losartan in the sub-Tenon tissue significantly decreased the expression of AT-1R, αSMA, TGF-β, and collagen type I in the cultured scleral fibroblasts and the sclera of systemic hypotensive rats. The sclera became less stiff after the losartan treatment. A significant increase in the number of RGCs and decrease in glial cell activation was found in the retina after the losartan treatment. These findings suggest that AngII plays a role in scleral fibrosis after systemic hypotension and that inhibiting AngII could modulate the tissue properties of the sclera, resulting in the protection of RGCs.
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Affiliation(s)
- Si-Eun Oh
- Department of Ophthalmology, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Jie-Hyun Kim
- Department of Ophthalmology, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Hee-Jong Shin
- Department of Ophthalmology, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Seong-Ah Kim
- Department of Ophthalmology, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Chan-Kee Park
- Department of Ophthalmology, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Hae-Young Lopilly Park
- Department of Ophthalmology, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
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Miao Y, Liu J, Akella SS, Wang J, Li S, Chuck RS, Zhang C. Changes in Rat Scleral Collagen Structure Induced by UVA-Riboflavin Crosslinking at Various Tissue Depths in Whole Globe Versus Scleral Patch. Transl Vis Sci Technol 2022; 11:2. [PMID: 35913416 PMCID: PMC9351595 DOI: 10.1167/tvst.11.8.2] [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] [Indexed: 11/24/2022] Open
Abstract
Purpose To investigate structural changes in scleral collagen fibers at various tissue depths before and after photosensitized crosslinking (CXL) both isolated scleral patch versus whole globe using second-harmonic generation (SHG) imaging. Methods Scleral tissues were harvested from Sprague-Dawley rats and separated into three groups: untreated sclera (control), full-thickness scleral patch for CXL (Free Scleral CXL group), and sclera in intact globe for CXL (Globe CXL group). The CXL groups were soaked in 0.1% riboflavin and irradiated with 365 nm ultraviolet-A light (power, 0.45 mW/cm2) for 30 minutes. SHG images were acquired every 5 µm between 10 and 60 µm from the outer scleral surface. Collagen fiber waviness was calculated as the ratio of the total length of a traced fiber and the length of a straight path between the fiber ends. Results In the Free Scleral CXL group, collagen waviness was significantly increased compared to the control group at 35 to 50 µm (P < 0.05). In the Globe CXL group, collagen waviness was decreased compared to control at all depths with statistical significance (P < 0.05) achieved from 10 to 45 µm. Conclusions Depending upon its initial state (i.e., free scleral patch versus mechanically loaded intact globe under pressure), collagen may experience different structural changes after CXL. In addition, the extent of the CXL effects may vary at different depths away from the surface. Translational Relevance Understanding the CXL effects on collagen structure may be important in optimizing the scleral crosslinking protocol for future clinical applications such as preventing myopic progression.
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Affiliation(s)
- Yuan Miao
- Aier School of Ophthalmology, Central South University, Changsha, Hunan, China.,Department of Ophthalmology & Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Juan Liu
- Department of Ophthalmology & Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, USA.,Department of Ophthalmology, People's Hospital of Ningxia Hui Autonomous Region, Yinchuan, Ningxia, China
| | - Sruti S Akella
- Department of Ophthalmology & Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Jessie Wang
- Department of Ophthalmology & Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Shaowei Li
- Aier School of Ophthalmology, Central South University, Changsha, Hunan, China
| | - Roy S Chuck
- Aier School of Ophthalmology, Central South University, Changsha, Hunan, China
| | - Cheng Zhang
- Aier School of Ophthalmology, Central South University, Changsha, Hunan, China
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Hamdaoui ME, Levy AM, Stuber AB, Girkin CA, Kraft TW, Samuels BC, Grytz R. Scleral crosslinking using genipin can compromise retinal structure and function in tree shrews. Exp Eye Res 2022; 219:109039. [PMID: 35339475 DOI: 10.1016/j.exer.2022.109039] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 03/08/2022] [Accepted: 03/13/2022] [Indexed: 01/29/2023]
Abstract
Scleral crosslinking using genipin has been identified as a promising treatment approach for myopia control. The efficacy of genipin to alter biomechanical properties of the sclera has been shown in several animal models of myopia but its safety profile remains unclear. In this safety study, we aim to investigate the effect of scleral crosslinking using retrobulbar injections of genipin on retinal structure and function at genipin doses that were shown to be effective in slowing myopia progression in juvenile tree shrews. To this end, three or five retrobulbar injections of genipin at 0 mM (sham), 10 mM, or 20 mM were performed in one eye every other day. Form deprivation myopia was induced in the injected eye. We quantified retinal function changes using full-field electroretinography and retinal structure changes using in vivo optical coherence tomography imaging and ex vivo histology. The optical coherence tomography results revealed significant thinning of the peripapillary retinal nerve fiber layer in all genipin treated groups including the lowest dose group, which showed no significant treatment effect in slowing myopia progression. In contrast, inducing form deprivation myopia alone and in combination with sham injections caused no obvious thinning of the retinal nerve fiber layer. Electroretinography results showed a significant desensitizing shift of the b-wave semi-saturation constant in the sham group and the second highest genipin dose group, and a significant reduction in b-wave maxima in the two highest genipin dose groups. The ex vivo histology revealed noticeable degeneration of photoreceptors and retinal pigment epithelium in one of two investigated eyes of the highest genipin dose group. While scleral crosslinking using genipin may still be a feasible treatment option for myopia control, our results suggest that repeated retrobulbar injections of genipin at 10 mM or higher are not safe in tree shrews. An adequate and sustained delivery strategy of genipin at lower concentrations will be needed to achieve a safe and effective scleral crosslinking treatment for myopia control in tree shrews. Caution should be taken if the proposed treatment approach is translated to humans.
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Affiliation(s)
- Mustapha El Hamdaoui
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Alexander M Levy
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Aaron B Stuber
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Christopher A Girkin
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Timothy W Kraft
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Brian C Samuels
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Rafael Grytz
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, USA.
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Wang Y, Wu Z, Liu B, Lu J, Tanumiharjo S, Huang J, Zhao X, Lu L. Efficacy and safety of scleral crosslinking using poly(ethylene glycol)ether tetrasuccinimidyl glutarate for form-deprivation myopia progression in rabbits. RSC Adv 2021; 11:31746-31755. [PMID: 35496866 PMCID: PMC9041537 DOI: 10.1039/d1ra05533j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 09/19/2021] [Indexed: 12/29/2022] Open
Abstract
Myopia is becoming increasingly prevalent worldwide at an alarming rate. However, no effective treatment is available for inhibiting myopia progression. Materials chemistry advancements have made it possible to regulate mechanical properties and rate of degradation with good compatibility by developing newly crosslinking systems such as the branched polyethylene glycol (PEG) systems. Herein, we presented a PEG molecule with N-hydroxysuccinimide (NHS) ester functional groups at the chain ends as a macromolecular crosslinking agent for the treatment of myopia. We found that the scleral collagen crosslinked with the four-armed star-shaped PEG molecule with NHS ester functional group (4S-PEG) showed better biomechanical properties, increased thermal stability and higher resistance to degradation. 4S-PEG exhibited relatively low cytotoxicity for human fetal scleral fibroblasts. The retrobulbar injection of 4S-PEG at a relatively low concentration (2.5 mM) showed good effective control of the progression of form-deprivation myopia in rabbits. There were no signs of adverse effect or damage by repeated injections with 4S-PEG in rabbits. The results of this work demonstrate that 4S-PEG can serve as a robust macromolecular crosslinking agent and is expected to have promise for application in the treatment of the progression of myopia.
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Affiliation(s)
- Yanbing Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University Guangzhou 510060 China
| | - Zhenquan Wu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University Guangzhou 510060 China
| | - Bingqian Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University Guangzhou 510060 China
| | - Jiang Lu
- Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Guangdong Provincial Key Laboratory for High Performance Resin-based Composites, School of Chemistry, Sun Yat-sen University Guangzhou 510275 China
| | - Silvia Tanumiharjo
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University Guangzhou 510060 China
| | - Jianbing Huang
- Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Guangdong Provincial Key Laboratory for High Performance Resin-based Composites, School of Chemistry, Sun Yat-sen University Guangzhou 510275 China
| | - Xiujuan Zhao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University Guangzhou 510060 China
| | - Lin Lu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University Guangzhou 510060 China
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Wang M, Corpuz CCC, Zhang F. Shaping Eyeballs by Scleral Collagen Cross-Linking: A Hypothesis for Myopia Treatment. Front Med (Lausanne) 2021; 8:655822. [PMID: 34277654 PMCID: PMC8282923 DOI: 10.3389/fmed.2021.655822] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 06/08/2021] [Indexed: 11/13/2022] Open
Abstract
The global prevalence of myopia has brought to the attention of the different eye and vision specialists, who make way to control its progression. Evidence have shown that a proactive reshaping of the eyeball is the core point of myopia developing process, which particularly includes the weakening, thinning, and expanding of the sclera. Thus, the sclera is considered to be a prime target for therapeutic manipulation in halting progressive myopia. In the past decades, corneal collagen cross-linking has been applied in clinical practice for treating aberrant corneal remodeling diseases. In this article, we hypothesize that scleral collagen cross-linking (SXL) has a huge potential in stabilizing myopic process by shaping the eyeball and preventing the aberrant scleral remodeling. In contrast with the current methods of optometry correction, such as physiotherapy, pharmacotherapy, spectacles, contact lenses, refractive surgeries, etc., eyeball-shaping method using SXL is a fundamental intervention which aims at the pathogenesis of progressive visual loss of myopia. Compared with the current posterior scleral reinforcement, the most advantage of SXL is that there is no allotransplant into the myopic eye, which means less expenditure, lower risk, and easier to handle in operating.
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Affiliation(s)
- Mengmeng Wang
- Hebei Ophthalmology Key Lab, Hebei Eye Hospital, Xingtai, China
| | | | - Fengju Zhang
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
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Han D, He MN, Zhu Y, Zhang Y, Wei RH. Protective effects of riboflavin-UVA-mediated posterior sclera collagen cross-linking in a guinea pig model of form-deprived myopia. Int J Ophthalmol 2021; 14:333-340. [PMID: 33747806 DOI: 10.18240/ijo.2021.03.01] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 12/21/2020] [Indexed: 01/17/2023] Open
Abstract
AIM To evaluate the effect of posterior sclera collagen cross-linking induced by riboflavin-ultraviolet A (UVA) on form-deprived myopia in guinea pigs. METHODES Twenty-five pigmented guinea pigs of 3-week-old were randomly assigned into 4 groups that included normal control (NOR, n=7), form-deprived (FDM, n=7), normal with riboflavin-UVA cross-linking (NOR+CL, n=5) and form-deprived with cross-linking (FDM+CL, n=6). The NOR+CL group and the FDM+CL group received the riboflavin-UVA induced cross-linking at day 0. FDM was induced by monocularly deprived with facemask in the right eyes. The refraction, axial length and corneal curvature were measured by retinoscopy, A-scan and keratometer respectively in scheduled time points (day 0 and 1, 2, 3, 4wk after form-deprivation). At the end of 4 weeks' experiment, stress-strain tests of sclera were measured and morphological changes of sclera and retina were examined. RESULTS After 4wk, the interocular difference of refractive error were -0.11±0.67, -2.93±0.56, 1.10±0.58, and -1.63±0.41 D in the NOR, FDM, NOR+CL, and FDM+CL groups respectively. Mixed-effect linear model revealed significant effect of FDM (P<0.01) and CL (P<0.001). Also, after 4wk, the interocular difference of axial length were 0.01±0.04, 0.29±0.07, -0.13±0.06, and 0.11±0.05 mm in the NOR, FDM, NOR+CL, and FDM+CL group. Mixed-effect linear model revealed significant effect of FDM (P<0.001) and CL (P<0.01). As for corneal curvature, significant interocular difference have not found between any of the two groups. At the end of this experiment, the ultimate stress and elastic modulus were found significantly increased in both CL groups. But no difference was found in the groups without cross-linked. There was no abnormality observed in the retina and RPE cells of the treated eyes. CONCLUSION The posterior sclera collagen cross-linking induced by riboflavin-UVA can slow down the progress of myopia and increase the sclera biomechanical strength in the guinea pig model of form-deprived myopia.
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Affiliation(s)
- Ding Han
- Tianjin Key Laboratory of Retinal Functions and Diseases, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin 300384, China
| | - Mei-Nan He
- Tianjin Key Laboratory of Retinal Functions and Diseases, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin 300384, China
| | - Ying Zhu
- Tianjin Key Laboratory of Retinal Functions and Diseases, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin 300384, China
| | - Yan Zhang
- Tianjin Key Laboratory of Retinal Functions and Diseases, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin 300384, China
| | - Rui-Hua Wei
- Tianjin Key Laboratory of Retinal Functions and Diseases, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin 300384, China
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7
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Boote C, Sigal IA, Grytz R, Hua Y, Nguyen TD, Girard MJA. Scleral structure and biomechanics. Prog Retin Eye Res 2019; 74:100773. [PMID: 31412277 DOI: 10.1016/j.preteyeres.2019.100773] [Citation(s) in RCA: 130] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 08/07/2019] [Accepted: 08/08/2019] [Indexed: 12/18/2022]
Abstract
As the eye's main load-bearing connective tissue, the sclera is centrally important to vision. In addition to cooperatively maintaining refractive status with the cornea, the sclera must also provide stable mechanical support to vulnerable internal ocular structures such as the retina and optic nerve head. Moreover, it must achieve this under complex, dynamic loading conditions imposed by eye movements and fluid pressures. Recent years have seen significant advances in our knowledge of scleral biomechanics, its modulation with ageing and disease, and their relationship to the hierarchical structure of the collagen-rich scleral extracellular matrix (ECM) and its resident cells. This review focuses on notable recent structural and biomechanical studies, setting their findings in the context of the wider scleral literature. It reviews recent progress in the development of scattering and bioimaging methods to resolve scleral ECM structure at multiple scales. In vivo and ex vivo experimental methods to characterise scleral biomechanics are explored, along with computational techniques that combine structural and biomechanical data to simulate ocular behaviour and extract tissue material properties. Studies into alterations of scleral structure and biomechanics in myopia and glaucoma are presented, and their results reconciled with associated findings on changes in the ageing eye. Finally, new developments in scleral surgery and emerging minimally invasive therapies are highlighted that could offer new hope in the fight against escalating scleral-related vision disorder worldwide.
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Affiliation(s)
- Craig Boote
- Structural Biophysics Research Group, School of Optometry & Vision Sciences, Cardiff University, UK; Ophthalmic Engineering & Innovation Laboratory (OEIL), Department of Biomedical Engineering, National University of Singapore, Singapore; Newcastle Research & Innovation Institute Singapore (NewRIIS), Singapore.
| | - Ian A Sigal
- Laboratory of Ocular Biomechanics, Department of Ophthalmology, University of Pittsburgh, USA
| | - Rafael Grytz
- Department of Ophthalmology & Visual Sciences, University of Alabama at Birmingham, USA
| | - Yi Hua
- Laboratory of Ocular Biomechanics, Department of Ophthalmology, University of Pittsburgh, USA
| | - Thao D Nguyen
- Department of Mechanical Engineering, Johns Hopkins University, USA
| | - Michael J A Girard
- Ophthalmic Engineering & Innovation Laboratory (OEIL), Department of Biomedical Engineering, National University of Singapore, Singapore; Singapore Eye Research Institute (SERI), Singapore National Eye Centre, Singapore
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8
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Lin X, Naidu RK, Dai J, Zhou X, Qu X, Zhou H. Scleral Cross-Linking Using Glyceraldehyde for the Prevention of Axial Elongation in the Rabbit: Blocked Axial Elongation and Altered Scleral Microstructure. Curr Eye Res 2018; 44:162-171. [PMID: 30222005 DOI: 10.1080/02713683.2018.1522647] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND This study aims to assess the efficacy of the scleral collagen cross-linking method using glyceraldehyde solution for prevention of lens-induced axial elongation in New Zealand rabbits and investigate the biochemical and microstructural changes that occur. METHODS The right eyes of New Zealand rabbits aged seven weeks were randomly divided into three groups: the cross-linking group (n = 6), non-crosslinking group (n = 5), and untreated control group (n = 5). Eyes in cross-linking and non-crosslinking groups were treated with a -8.00 Diopter spherical lens over the course of two weeks. The cross-linking effects were achieved by a sub-Tenon's injection of 0.15 ml 0.5 M glyceraldehyde to eyes in the CL group. Ocular parameters were measured on the 1st, 7th, and 14th days. Biomechanical testing, light and electronic microscopy were used. RESULTS Following the cross-linking treatment, eyes in the cross-linking group had a shorter axial length compared to those in the non-crosslinking group (p = 0.006). Collagen fibrils larger than 240 nm were observed in the scleral stroma of cross-linking group, which were absent in the scleral stroma of the non-crosslinking and untreated control group. The mean ultimate stress and Young's modulus was significantly greater in the cross-linking group compared to those in the non-crosslinking and untreated control group (p < 0.05). No histological damage observed in the retina or choroid. CONCLUSIONS This study demonstrates that lens-induced axial elongation in rabbits can be effectively blocked by cross-linking using glyceraldehyde, with anatomical and mechanical modification and no deleterious effects.
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Affiliation(s)
- Xiao Lin
- a Department of Ophthalmology & Visual Science , Fudan University Eye Ear Nose and Throat Hospital, Shanghai Medical College, Fudan University , Shanghai , China.,b Key Laboratory of Myopia, Ministry of Health , Fudan University , Shanghai , China.,c Shanghai Key Laboratory of Visual Impairment and Restoration , Fudan University , Shanghai , China
| | - Rajeev K Naidu
- d Concord Repatriation General Hospital , The University of Sydney , Camperdown , Australia
| | - Jinhui Dai
- a Department of Ophthalmology & Visual Science , Fudan University Eye Ear Nose and Throat Hospital, Shanghai Medical College, Fudan University , Shanghai , China.,b Key Laboratory of Myopia, Ministry of Health , Fudan University , Shanghai , China.,c Shanghai Key Laboratory of Visual Impairment and Restoration , Fudan University , Shanghai , China
| | - Xingtao Zhou
- a Department of Ophthalmology & Visual Science , Fudan University Eye Ear Nose and Throat Hospital, Shanghai Medical College, Fudan University , Shanghai , China.,b Key Laboratory of Myopia, Ministry of Health , Fudan University , Shanghai , China.,c Shanghai Key Laboratory of Visual Impairment and Restoration , Fudan University , Shanghai , China
| | - Xiaomei Qu
- a Department of Ophthalmology & Visual Science , Fudan University Eye Ear Nose and Throat Hospital, Shanghai Medical College, Fudan University , Shanghai , China.,b Key Laboratory of Myopia, Ministry of Health , Fudan University , Shanghai , China.,c Shanghai Key Laboratory of Visual Impairment and Restoration , Fudan University , Shanghai , China
| | - Hao Zhou
- a Department of Ophthalmology & Visual Science , Fudan University Eye Ear Nose and Throat Hospital, Shanghai Medical College, Fudan University , Shanghai , China.,b Key Laboratory of Myopia, Ministry of Health , Fudan University , Shanghai , China.,c Shanghai Key Laboratory of Visual Impairment and Restoration , Fudan University , Shanghai , China
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9
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Campbell IC, Hannon BG, Read AT, Sherwood JM, Schwaner SA, Ethier CR. Quantification of the efficacy of collagen cross-linking agents to induce stiffening of rat sclera. J R Soc Interface 2017; 14:rsif.2017.0014. [PMID: 28381643 DOI: 10.1098/rsif.2017.0014] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Accepted: 03/09/2017] [Indexed: 11/12/2022] Open
Abstract
The concept of scleral stiffening therapies has emerged as a novel theoretical approach for treating the ocular disorders glaucoma and myopia. Deformation of specific regions of the posterior eye is innately involved in the pathophysiology of these diseases, and thus targeted scleral stiffening could resist these changes and slow or prevent progression of these diseases. Here, we present the first systematic screen and direct comparison of the stiffening effect of small molecule collagen cross-linking agents in the posterior globe, namely using glyceraldehyde, genipin and methylglyoxal (also called pyruvaldehyde). To establish a dose-response relationship, we used inflation testing to simulate the effects of increasing intraocular pressure in freshly harvested rat eyes stiffened with multiple concentrations of each agent. We used digital image correlation to compute the mechanical strain in the tissue as a metric of stiffness, using a novel treatment paradigm for screening relative stiffening by incubating half of each eye in cross-linker and using the opposite half as an internal control. We identified the doses necessary to increase stiffness by approximately 100%, namely 30 mM for glyceraldehyde, 1 mM for genipin and 7 mM for methylglyoxal, and we also identified the range of stiffening it was possible to achieve with such agents. Such findings will inform development of in vivo studies of scleral stiffening to treat glaucoma and myopia.
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Affiliation(s)
- Ian C Campbell
- Center for Visual and Neurocognitive Rehabilitation, Rehabilitation Research and Development, Atlanta VA Medical Center, Decatur, GA 30033, USA.,Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA.,Exponent, Inc., Biomechanics Practice, Atlanta, GA 30326, USA
| | - Bailey G Hannon
- Center for Visual and Neurocognitive Rehabilitation, Rehabilitation Research and Development, Atlanta VA Medical Center, Decatur, GA 30033, USA.,George W. Woodruff Department of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - A Thomas Read
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
| | - Joseph M Sherwood
- Department of Bioengineering, Faculty of Engineering, Imperial College London, London SW7 2AZ, UK
| | - Stephen A Schwaner
- George W. Woodruff Department of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - C Ross Ethier
- Center for Visual and Neurocognitive Rehabilitation, Rehabilitation Research and Development, Atlanta VA Medical Center, Decatur, GA 30033, USA .,Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA.,George W. Woodruff Department of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
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10
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Iontophoresis-assisted accelerated riboflavin/ultraviolet A scleral cross-linking: A potential treatment for pathologic myopia. Exp Eye Res 2017; 162:37-47. [DOI: 10.1016/j.exer.2017.07.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 06/16/2017] [Accepted: 07/05/2017] [Indexed: 12/23/2022]
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11
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Kwok SJJ, Kim M, Lin HH, Seiler TG, Beck E, Shao P, Kochevar IE, Seiler T, Yun SH. Flexible Optical Waveguides for Uniform Periscleral Cross-Linking. Invest Ophthalmol Vis Sci 2017; 58:2596-2602. [PMID: 28494493 PMCID: PMC5433838 DOI: 10.1167/iovs.17-21559] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Purpose Scleral cross-linking (SXL) with a photosensitizer and light is a potential strategy to mechanically reinforce the sclera and prevent progressive axial elongation responsible for severe myopia. Current approaches for light delivery to the sclera are cumbersome, do not provide uniform illumination, and only treat a limited area of sclera. To overcome these challenges, we developed flexible optical waveguides optimized for efficient, homogeneous light delivery. Methods Waveguides were fabricated from polydimethylsiloxane elastomer. Blue light (445 nm) is coupled into the waveguide with an input fiber. Light delivery efficiency from the waveguide to scleral tissue was measured and fit to a theoretical model. SXL was performed on fresh porcine eyes stained with 0.5% riboflavin, using irradiances of 0, 25, and 50 mW/cm2 around the entire equator of the eye. Stiffness of scleral strips was characterized with tensiometry. Results Light delivery with a waveguide of tapered thickness (1.4–0.5 mm) enhanced the uniformity of light delivery, compared to a flat waveguide, achieving a coefficient of variation of less than 10%. At 8% strain, sclera cross-linked with the waveguides at 50 mW/cm2 for 30 minutes had a Young's modulus of 10.7 ± 1.0 MPa, compared to 5.9 ± 0.5 MPa for no irradiation, with no difference in stiffness between proximally and distally treated halves. The stiffness of waveguide-irradiated samples did not differ from direct irradiation at the same irradiance. Conclusions We developed flexible waveguides for periscleral cross-linking. We demonstrated efficient and uniform stiffening of a 5-mm-wide equatorial band of scleral tissue.
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Affiliation(s)
- Sheldon J J Kwok
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States 2Harvard-MIT Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
| | - Moonseok Kim
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
| | - Harvey H Lin
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
| | - Theo G Seiler
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States 3Institute for Refractive and Ophthalmic Surgery (IROC), Zurich, Switzerland
| | - Eric Beck
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
| | - Peng Shao
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
| | - Irene E Kochevar
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
| | - Theo Seiler
- Institute for Refractive and Ophthalmic Surgery (IROC), Zurich, Switzerland
| | - Seok-Hyun Yun
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States 2Harvard-MIT Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
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Iomdina ЕN, Tarutta ЕP, Semchishen VА, Korigodskiy АR, Zakharov ID, Khoroshilova-Maslova IP, Ignat'eva NY, Kiseleva ТN, Sianosyan АА, Milash SV. [Experimental realization of minimally invasive techniques of scleral collagen cross-linking]. Vestn Oftalmol 2017; 132:49-58. [PMID: 28121299 DOI: 10.17116/oftalma2016132649-56] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
AIM To realize two minimally invasive techniques of scleral collagen cross-linking (SXL) at the equator and posterior pole of the eye: 1) targeted irradiation of the region with ultraviolet A (UVA) and 2) sub-Tenon injection of Sklerateks. MATERIAL AND METHODS To perform UVA-SXL, a tool was developed that includes a UV-LED light source (370 nm, 3 mW/cm2) and a polymer-coated silica multimode optical fiber located in one of the two channels of a detachable metal tip. The other channel is used to deliver riboflavin to the scleral surface. The study included 8 Chinchillas' eyes. Intact fellow eyes served as the controls. Scleral echodensity was measured in vivo with Voluson 730 Pro (Kretz) prior to the procedure and then 2 days and 1 month after. After enucleation, the elastic modulus and the degree of scleral cross-linking were established at the same time-points. A placebo-controlled study on the safety and effectiveness of sub-Tenon Sklerateks injections (solution of amino acid salts in the form of succinates) was conducted on 47 Chinchilla rabbits (94 eyes). Sklerateks or placebo (0.1 ml) was injected below the Tenon's capsule of either eye once a week for 1 month (4 injections; 1st series) or 3 months (12 injections; 2nd series). After the end of the course, 22 eyes were studied morphologically. In 72 eyes, scleral samples were obtained in order to evaluate the elastic modulus (Autograph AGS-H tester, SHIMADZU, Japan) and the rate of cross-linking (judging from the denaturation temperature) by differential scanning calorimetry (Phoenix DSC 204 calorimeter, Netzsch, Germany). RESULTS After UVA irradiation, the scleral echodensity increased from 86.7±5.1 to 98±4.9 dB. The elastic modulus appeared 1.5 times higher than that of the control samples. The denaturation temperature also increased indicating the rate of scleral cross-linking as high as 15-18%. Weekly Sklerateks for 1-3 months has been shown to induce neither clinical, nor morphological signs of local irritative, damaging, or toxic effect. The findings also include: a 1.8 times higher rate of scleral cross-linking, activation of cellular elements, neoformation of connective tissue on the scleral surface, and vascular growth, which together indicate a pronounced metabolic and strengthening effect of Sklerateks on the sclera. CONCLUSION Experimental results on minimally invasive techniques of SXL allow to recommend them for further clinical investigation as a promising treatment of progressive myopia.
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Affiliation(s)
- Е N Iomdina
- Moscow Helmholtz Research Institute of Eye Diseases, Ministry of Health of the Russian Federation, 14/19 Sadovaya-Chernogryazskaya St., Moscow, 105062, Russian Federation
| | - Е P Tarutta
- Moscow Helmholtz Research Institute of Eye Diseases, Ministry of Health of the Russian Federation, 14/19 Sadovaya-Chernogryazskaya St., Moscow, 105062, Russian Federation
| | - V А Semchishen
- Federal Research Center 'Crystallography and photonics', Russian Academy of Sciencs, 59 Leninskiy prospekt, Moscow, 119333, Russian Federation
| | - А R Korigodskiy
- HajBiTek LLC, 44-1 Mira prospekt, Moscow, Russian Federation, 129110
| | - I D Zakharov
- HajBiTek LLC, 44-1 Mira prospekt, Moscow, Russian Federation, 129110
| | - I P Khoroshilova-Maslova
- Moscow Helmholtz Research Institute of Eye Diseases, Ministry of Health of the Russian Federation, 14/19 Sadovaya-Chernogryazskaya St., Moscow, 105062, Russian Federation
| | - N Yu Ignat'eva
- Lomonosov Moscow State University, 1 Leninskie Gory, Moscow, 119991, Russian Federation
| | - Т N Kiseleva
- Moscow Helmholtz Research Institute of Eye Diseases, Ministry of Health of the Russian Federation, 14/19 Sadovaya-Chernogryazskaya St., Moscow, 105062, Russian Federation
| | - А А Sianosyan
- Moscow Helmholtz Research Institute of Eye Diseases, Ministry of Health of the Russian Federation, 14/19 Sadovaya-Chernogryazskaya St., Moscow, 105062, Russian Federation
| | - S V Milash
- Moscow Helmholtz Research Institute of Eye Diseases, Ministry of Health of the Russian Federation, 14/19 Sadovaya-Chernogryazskaya St., Moscow, 105062, Russian Federation
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The Effects of Scleral Collagen Cross-Linking Using Glyceraldehyde on the Progression of Form-Deprived Myopia in Guinea Pigs. J Ophthalmol 2016; 2016:3526153. [PMID: 27504195 PMCID: PMC4967684 DOI: 10.1155/2016/3526153] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 06/19/2016] [Indexed: 12/04/2022] Open
Abstract
To investigate the effects of collagen cross-linking using glyceraldehyde on the biomechanical properties of the sclera and the axial elongation of form-deprived myopia in the guinea pig. Thirty-six guinea pigs were randomly assigned to four groups: FDM (form-deprived myopia); FDMG (form-deprived myopia treated with glyceraldehyde); FDMS (form-deprived myopia treated with 0.9% isotonic sodium chloride); and normal control (free of form-deprivation). FDM was achieved in the right eye using a latex facemask. The right eye in FDMG was treated with a posterior subtenon injection of 0.5 M glyceraldehyde; 0.9% isotonic sodium chloride was administered to the right eye in FDMS group using the same method. Axial length, refraction, and stress-strain of the sclera were measured at scheduled time points. The treated eyes were also examined histologically by light microscopy. It was found that glyceraldehyde treatment significantly increased the stiffness of the sclera in the FDM eyes and abnormalities have not been observed in the retina and optic nerve of the treated eyes. But the development of myopia was not affected.
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14
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Effect of Glyceraldehyde Cross-Linking on a Rabbit Bullous Keratopathy Model. J Ophthalmol 2015; 2015:171690. [PMID: 26509077 PMCID: PMC4609852 DOI: 10.1155/2015/171690] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Revised: 07/14/2015] [Accepted: 07/26/2015] [Indexed: 11/18/2022] Open
Abstract
Background. To evaluate the effects of corneal glyceraldehyde CXL on the rabbit bullous keratopathy models established by descemetorhexis. Methods. Fifteen rabbits were randomly divided into five groups. Group A (n = 3) is the control group. The right eyes of animals in Groups B,C, D, and E (n = 3, resp.) were suffered with descemetorhexis procedures. From the 8th day to the 14th day postoperatively, the right eyes in Groups C and D were instilled with hyperosmolar drops and glyceraldehyde drops, respectively; the right eyes in Group E were instilled with both hyperosmolar drops and glyceraldehyde drops. Central corneal thickness (CCT), corneal transparency score, and histopathological analysis were applied on the eyes in each group. Results. Compared with Group A, statistically significant increase in CCT and corneal transparency score was found in Groups B, C, D, and E at 7 d postoperatively (P < 0.05) and in Groups C, D, and E at 14 d postoperatively (P < 0.05). Conclusion. Chemical CXL technique using glyceraldehyde improved the CCT and corneal transparency of the rabbit bullous keratopathy models. Topical instillation with glyceraldehyde and hyperosmolar solutions seems to be a good choice for the bullous keratopathy treatment.
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Grytz R, Siegwart JT. Changing material properties of the tree shrew sclera during minus lens compensation and recovery. Invest Ophthalmol Vis Sci 2015; 56:2065-78. [PMID: 25736788 DOI: 10.1167/iovs.14-15352] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PURPOSE To estimate two collagen-specific material properties (crimp angle and elastic modulus of collagen fibrils) of the remodeling tree shrew sclera during monocular -5 diopter (D) lens wear and recovery. METHODS Tensile tests were performed on scleral strips obtained from juvenile tree shrews exposed to three different visual conditions: normal, monocular -5 D lens wear to induce myopia, and recovery. Collagen fibrils are crimped in the unloaded sclera and uncrimp as the tissue stiffens under load. Inverse numerical analyses were performed to estimate the (unloaded) crimp angle and elastic modulus of collagen fibrils using a microstructure-based constitutive model. RESULTS Compared with the control eye, the crimp angle was significantly higher in the treated eye after 2 days and remained significantly higher until 21 days of lens wear (P < 0.05). The difference between the crimp angle of the treated and control eye rapidly vanished during recovery in concert with the changes in axial elongation rate. A rapid and extensive increase in the elastic modulus was seen in both eyes after starting and stopping the lens wear. CONCLUSIONS The estimated change in the crimp of scleral collagen fibrils is temporally associated with the change in axial elongation rate during myopia development and recovery. This finding suggests that axial elongation may be controlled by a remodeling mechanism that modulates the collagen fibril crimp. The observed binocular changes in scleral stiffness are not temporally associated with the axial elongation rate, indicating that scleral stiffening may not be causally related to myopia.
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Affiliation(s)
- Rafael Grytz
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - John T Siegwart
- Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, Alabama, United States
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16
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Kimball EC, Nguyen C, Steinhart MR, Nguyen TD, Pease ME, Oglesby EN, Oveson BC, Quigley HA. Experimental scleral cross-linking increases glaucoma damage in a mouse model. Exp Eye Res 2014; 128:129-40. [PMID: 25285424 PMCID: PMC4254118 DOI: 10.1016/j.exer.2014.08.016] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 07/21/2014] [Accepted: 08/07/2014] [Indexed: 12/12/2022]
Abstract
The purpose of this study was to assess the effect of a scleral cross-linking agent on susceptibility to glaucoma damage in a mouse model.CD1 mice underwent 3 subconjunctival injections of 0.5 M glyceraldehyde (GA) in 1 week, then had elevated intraocular pressure (IOP) induced by bead injection. Degree of cross-linking was measured by enzyme-linked immunosorbent assay (ELISA), scleral permeability was measured by fluorescence recovery after photobleaching (FRAP), and the mechanical effects of GA exposure were measured by inflation testing. Control mice had buffer injection or no injection in 2 separate glaucoma experiments. IOP was monitored by Tonolab and retinal ganglion cell (RGC) loss was measured by histological axon counting. To rule out undesirable effects of GA, we performed electroretinography and detailed histology of the retina. GA exposure had no detectable effects on RGC number, retinal structure or function either histologically or electrophysiologically. GA increased cross-linking of sclera by 37% in an ELISA assay, decreased scleral permeability (FRAP, p = 0.001), and produced a steeper pressure-strain behavior by in vitro inflation testing. In two experimental glaucoma experiments, GA-treated eyes had greater RGC axon loss from elevated IOP than either buffer-injected or control eyes, controlling for level of IOP exposure over time (p = 0.01, and 0.049, multivariable regression analyses). This is the first report that experimental alteration of the sclera, by cross-linking, increases susceptibility to RGC damage in mice.
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Affiliation(s)
- Elizabeth C Kimball
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, MD, USA.
| | - Cathy Nguyen
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Matthew R Steinhart
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Thao D Nguyen
- The Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Mary E Pease
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Ericka N Oglesby
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Brian C Oveson
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Harry A Quigley
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, MD, USA
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17
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Wang M, Zhang F, Liu K, Zhao X. Safety evaluation of rabbit eyes on scleral collagen cross-linking by riboflavin and ultraviolet A. Clin Exp Ophthalmol 2014; 43:156-63. [DOI: 10.1111/ceo.12392] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2013] [Accepted: 07/06/2014] [Indexed: 12/22/2022]
Affiliation(s)
- Mengmeng Wang
- Beijing Tongren Eye Center; Beijing Ophthalmology & Visual Sciences Key Lab; Beijing Tongren Hospital of Capital Medical University; Beijing
- Hebei Ophthalmology Key Lab; Hebeisheng Eye Hospital; Xingtai Hebei Province China
| | - Fengju Zhang
- Beijing Tongren Eye Center; Beijing Ophthalmology & Visual Sciences Key Lab; Beijing Tongren Hospital of Capital Medical University; Beijing
| | - Kegao Liu
- Beijing Tongren Eye Center; Beijing Ophthalmology & Visual Sciences Key Lab; Beijing Tongren Hospital of Capital Medical University; Beijing
| | - Xu Zhao
- Beijing Tongren Eye Center; Beijing Ophthalmology & Visual Sciences Key Lab; Beijing Tongren Hospital of Capital Medical University; Beijing
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18
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Kim M, Takaoka A, Hoang QV, Trokel SL, Paik DC. Pharmacologic alternatives to riboflavin photochemical corneal cross-linking: a comparison study of cell toxicity thresholds. Invest Ophthalmol Vis Sci 2014; 55:3247-57. [PMID: 24722697 PMCID: PMC4037937 DOI: 10.1167/iovs.13-13703] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 04/01/2014] [Indexed: 02/02/2023] Open
Abstract
PURPOSE The efficacy of therapeutic cross-linking of the cornea using riboflavin photochemistry (commonly abbreviated as CXL) has caused its use to become widespread. Because there are known chemical agents that cross-link collagenous tissues, it may be possible to cross-link tissue pharmacologically. The present study was undertaken to compare the cell toxicity of such agents. METHODS Nine topical cross-linking agents (five nitroalcohols, glyceraldehyde [GLYC], genipin [GP], paraformaldehyde [FA], and glutaraldehyde [GLUT]) were tested with four different cell lines (immortalized human corneal epithelial cells, human skin fibroblasts, primary bovine corneal endothelial cells, and immortalized human retinal pigment epithelial cells [ARPE-19]). The cells were grown in planar culture and exposed to each agent in a range of concentrations (0.001 mM to 10 mM) for 24 hours followed by a 48-hour recovery phase. Toxicity thresholds were determined by using the trypan blue exclusion method. RESULTS A semiquantitative analysis using five categories of toxicity/fixation was carried out, based on plate attachment, uptake of trypan blue stain, and cellular fixation. The toxicity levels varied by a factor of 10(3) with the least toxic being mononitroalcohols and GLYC, intermediate toxicity for a nitrodiol and nitrotriol, and the most toxic being GLUT, FA, GP, and bronopol, a brominated nitrodiol. When comparing toxicity between different cell lines, the levels were generally in agreement. CONCLUSIONS There are significant differences in cell toxicity among potential topical cross-linking compounds. The balance between cross-linking of tissue and cell toxicity should be borne in mind as compounds and strategies to improve mechanical tissue properties through therapeutic tissue cross-linking continue to develop.
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Affiliation(s)
- MiJung Kim
- Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, New York, New York, United States
| | - Anna Takaoka
- Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, New York, New York, United States
| | - Quan V Hoang
- Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, New York, New York, United States
| | - Stephen L Trokel
- Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, New York, New York, United States
| | - David C Paik
- Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, New York, New York, United States
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Taneri S, Oehler S, Asimellis G, Kanellopoulos AJ. Influence of corneal cross-linking for keratoconus on several objective parameters of dry eye. J Refract Surg 2013; 29:612-6. [PMID: 24016346 DOI: 10.3928/1081597x-20130819-02] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 05/02/2013] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate the potential influence of corneal cross-linking (CXL) with ultraviolet-A light and riboflavin in keratoconic eyes on several objective parameters of dry eye syndrome. METHODS This prospective single center study included 30 consecutive eyes of 16 patients that underwent CXL with riboflavin and ultraviolet-A treatment (epithelial removal, 30 minutes soaking with riboflavin, 30 minutes of illumination with 365 nm, 3 mW/cm(2), 5 cm distance). Several dry eye syndrome parameters were evaluated preoperatively and 3 and 6 months after the procedure: intra-individual comparison of fluorescein and Rose bengal staining, height of tear film meniscus, and tear film break-up time. RESULTS Pathologic staining (more than 10 point-shaped areas or diffuse staining) with fluorescein was evident before CXL in 1 eye, 3 months after CXL in 1 eye, and 6 months after CXL in 1 eye. Rose bengal staining 3 and 6 months postoperatively was comparable to preoperative staining. Tear film height was reduced in 2 eyes before CXL and in 4 eyes 3 months postoperatively, and was normal in all eyes after 6 months. The number of eyes with reduced tear film break-up time was not significantly changed. CONCLUSIONS CXL had no significant impact on several parameters of dry eye syndrome 3 and 6 months postoperatively.
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Affiliation(s)
- Suphi Taneri
- Eye Department, St. Francis Hospital, Muenster, Germany.
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Aliphatic β-nitroalcohols for therapeutic corneoscleral cross-linking: corneal permeability considerations. Cornea 2013; 32:179-84. [PMID: 22868628 DOI: 10.1097/ico.0b013e31825646de] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PURPOSE Our recent tissue cross-linking studies have raised the possibility of using aliphatic β-nitroalcohols (BNAs) for pharmacologic, therapeutic corneal cross-linking. The present study was performed to determine the permeability of BNAs and to explore the use of permeability-enhancing agents. METHODS Ex vivo rabbit corneas were mounted in a typical Franz diffusion chamber. BNA permeability was determined by assaying the recipient chamber over time using a modification of the Griess nitrite colorimetric assay. The apparent permeability coefficient (Ptot) was determined for 2 mono-nitroalcohols [2-nitroethanol (2ne) and 2-nitro-1-propanol (2nprop)], a nitrodiol [2-methyl-2-nitro-1,3-propanediol (MNPD)], and a nitrotriol [2-hydroxymethyl-2-nitro-1,3-propanediol (HNPD)]. Permeability-enhancing effects using benzalkonium chloride (BAC) (0.01% and 0.02%), ethylenediaminetetraacetic acid (0.05%), and a combination of 0.01% BAC + 0.5% tetracaine were also studied. RESULTS The Ptot (±SE) values (in centimeters per second) were as follows: 4.33 × 10 (±9.82 × 10) for 2ne [molecular weight (MW) = 91 Da], 9.34 × 10 (±2.16 × 10) for 2nprop (MW = 105 Da), 4.37 × 10 (±1.86 × 10) for MNPD (MW = 135 Da), and 8.95 × 10 (±1.93 × 10) for HNPD (MW = 151 Da). Using the nitrodiol, permeability increased approximately 2-fold using 0.01% BAC, 5-fold using 0.02% BAC, and 5-fold using the combination of 0.01% BAC + 0.5% tetracaine. No effect was observed using 0.05% ethylenediaminetetraacetic acid. CONCLUSIONS The results indicate that the corneal epithelium is permeable to BNAs, with the apparent permeability corresponding to MW. The findings are consistent with previous literature indicating that the small size of these compounds (<10Å) favors their passage through the corneal epithelium via the paracellular route. This information will help to guide dosing regimens for in vivo topical cross-linking studies.
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Strouthidis NG, Girard MJA. Altering the way the optic nerve head responds to intraocular pressure—a potential approach to glaucoma therapy. Curr Opin Pharmacol 2013; 13:83-9. [DOI: 10.1016/j.coph.2012.09.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 09/04/2012] [Indexed: 10/27/2022]
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Wen Q, Paik DC. Using the Griess colorimetric nitrite assay for measuring aliphatic β-nitroalcohols. Exp Eye Res 2012; 98:52-7. [PMID: 22406005 DOI: 10.1016/j.exer.2012.01.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Revised: 01/13/2012] [Accepted: 01/17/2012] [Indexed: 10/28/2022]
Affiliation(s)
- Quan Wen
- Laboratory for Tissue Cross-linking, Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, 160 Fort Washington Ave, Room 715, New York, NY 10032, USA
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Hwang YJ, Granelli J, Lyubovitsky J. Effects of zero-length and non-zero-length cross-linking reagents on the optical spectral properties and structures of collagen hydrogels. ACS APPLIED MATERIALS & INTERFACES 2012; 4:261-267. [PMID: 22132996 DOI: 10.1021/am2013147] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We compared the effects of zero-length cross-linkers 1-ethyl-3 (3dimethylaminopropyl) carbodiimide (EDC) and non-zero-length cross-linkers glycolaldehyde and glyceraldehyde on the optical and structural properties of three-dimensional (3D) collagen hydrogels. We evaluated these effects by multiphoton microscopy (MPM) that combined two-photon fluorescence (TPF) and second harmonic generation (SHG) contrasts and transmission electron microscopy (TEM). The collagen hydrogels were incubated separately with the above-mentioned reagents present at the concentration of 0.1 M. The incubation with glycolaldehyde and glyceraldehyde induced strong autofluorescence within the gels. We followed the formation of fluorescence with TPF signals in situ and in real time as well as characterized the micro- and nanostructures within cross-linked hydrogels by examining SHG and TEM images respectively. As detected in the SHG images, glycolaldehyde- and glyceraldehyde-modified 5-10 μm "fiberlike" collagen structures to longer, 20 μm and more, aggregated strands while EDC had minimal effect on the microstructure. TEM revealed that glycolaldehyde and glyceraldehyde either completely eliminated collagen's characteristic native fibrillar striations or generated uncharacteristic fibrils with extensions. EDC preserved the native striation patterns, decreased the fibril diameters and effectively homogenized the fibrils within hydrogels assembled at 1.8-4.68 g/L collagen concentrations and 37 °C. Our findings provide a clear understanding on how different cross-linking reagents have very different effects on the collagen hydrogels. This understanding is critical for advancing tissue engineering and wound healing applications.
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Affiliation(s)
- Yu-Jer Hwang
- University of Califorina at Riverside, Riverside, California, USA
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Scleral mechanics: comparing whole globe inflation and uniaxial testing. Exp Eye Res 2011; 94:128-35. [PMID: 22155444 DOI: 10.1016/j.exer.2011.11.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 11/21/2011] [Accepted: 11/23/2011] [Indexed: 11/20/2022]
Abstract
The purpose of this study was to assess fundamental differences between the mechanics of the posterior sclera in paired eyes using uniaxial and whole globe inflation testing, with an emphasis on the relationship between testing conditions and observed tissue behavior. Twenty porcine eyes, consisting of matched pairs from 10 pigs, were used in this study. Within pairs, one eye was tested with 10 cycles of globe pressurization to 150 mmHg (∼10× normal IOP) while biaxial strains were tracked via an optical system at the posterior sclera. An excised posterior strip from the second eye was subjected to traditional uniaxial testing in which mechanical hysteresis was recorded from 10 cycles to a peak stress of 0.13 MPa (roughly equivalent to the circumferential wall stress produced by an IOP of 150 mmHg under the thin-walled pressure vessel assumption). For approximately equivalent loads, peak strains were more than twice as high in uniaxial tests than in inflation tests. Different trends in the load-deformation plots were seen between the tests, including an extended "toe" region in the uniaxial test, a generally steeper curve in the inflation tests, and reduced variability in the inflation tests. The unique opportunity of being able to mechanically load a whole globe under near physiologic conditions alongside a standard uniaxially tested specimen reveals the effects of testing artifacts relevant to most uniaxially tested soft tissues. Whole globe inflation offers testing conditions that significantly alter load-deformation behavior relative to uniaxial testing; consequently, laboratory studies of interventions or conditions that alter scleral mechanics may greatly benefit from these findings.
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Wollensak G. Thermomechanical stability of sclera after glyceraldehyde crosslinking. Graefes Arch Clin Exp Ophthalmol 2010; 249:399-406. [DOI: 10.1007/s00417-010-1504-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2010] [Revised: 07/28/2010] [Accepted: 08/26/2010] [Indexed: 11/24/2022] Open
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Mattson MS, Huynh J, Wiseman M, Coassin M, Kornfield JA, Schwartz DM. An in vitro intact globe expansion method for evaluation of cross-linking treatments. Invest Ophthalmol Vis Sci 2010; 51:3120-8. [PMID: 20071684 PMCID: PMC2891471 DOI: 10.1167/iovs.09-4001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Revised: 10/06/2009] [Accepted: 12/15/2009] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To measure the tissue mechanical response to elevated intraocular pressure (IOP) using intact globe expansion of rabbit eyes. This method examined rabbit kit (2-3 weeks old) eyes as a model for weakened tissue and evaluated riboflavin/UVA and glyceraldehyde cross-linking treatments. METHODS The ocular shape of enucleated eyes was photographed during a 24-hour period while a controlled IOP was imposed (either low IOP = 22 mm Hg or high IOP = 85 mm Hg). Untreated controls consisted of kit eyes tested at both low- and high IOP and adult eyes tested at high IOP. Treated kit eyes (dextran controls, riboflavin/UVA treatment of the cornea, and glyceraldehyde treatment of the entire globe) were tested at high IOP. RESULTS Low IOP elicited negligible creep of the sclera and very gradual creep of the cornea. In contrast, high IOP induced up to an 8% strain in the sclera and a 15% strain in the cornea of rabbit kit eyes. The expansion of adult eyes was less than one third that of kit eyes at the same, high IOP. Riboflavin/UVA treatment of corneas reduced expansion compared with that in both dextran-treated and untreated control corneas. Glyceraldehyde treatment prevented expansion of the cornea and sclera. CONCLUSIONS The intact globe expansion method (GEM) imposes a loading geometry comparable to in vivo conditions and can quantify changes in mechanical stability as a function of testing conditions (e.g., IOP, tissue maturation, and therapeutic cross-linking) with small sample sizes and small variability. Rabbit kit eyes provide a model of weak tissue suitable for screening treatments that strengthen the cornea and sclera.
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Affiliation(s)
- Matthew S. Mattson
- From the Departments of Engineering and Applied Science and
- the Department of Ophthalmology, University of California, San Francisco, San Francisco, California
| | - Joyce Huynh
- Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California; and
| | - Meredith Wiseman
- Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California; and
| | - Marco Coassin
- the Department of Ophthalmology, University of California, San Francisco, San Francisco, California
| | - Julia A. Kornfield
- Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California; and
| | - Daniel M. Schwartz
- the Department of Ophthalmology, University of California, San Francisco, San Francisco, California
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Wollensak G. Histological changes in human cornea after cross-linking with riboflavin and ultraviolet A. Acta Ophthalmol 2010; 88:e17-8. [PMID: 19432845 DOI: 10.1111/j.1755-3768.2008.01474.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Wang X, Nyman J, Dong X, Leng H, Reyes M. Fundamental Biomechanics in Bone Tissue Engineering. ACTA ACUST UNITED AC 2010. [DOI: 10.2200/s00246ed1v01y200912tis004] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Sisson K, Zhang C, Farach-Carson MC, Chase DB, Rabolt JF. Evaluation of cross-linking methods for electrospun gelatin on cell growth and viability. Biomacromolecules 2009; 10:1675-80. [PMID: 19456101 DOI: 10.1021/bm900036s] [Citation(s) in RCA: 222] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The creation of a tissue engineering scaffold via electrospinning that has minimal toxicity and uses a solvent system composed of solvents with low toxicity and different cross-linking agents was investigated. First, a solvent system of acetic acid/ethyl acetate/water (50:30:20) with gelatin as a solute was evaluated. The optimum system for electrospinning a scaffold with the desired properties resulted from a gelatin concentration of 10 wt %. Several different methods were used to cross-link the electrospun gelatin fibers, including vapor-phase glutaraldehyde, aqueous phase genipin, and glyceraldehyde, as well as reactive oxygen species from a plasma cleaner. Because glutaraldehyde at high concentrations has been shown to be toxic, we explored other cross-linking methods. Using reactive oxygen species from a plasma cleaner is an easy alternative; however, the degradation reaction dominated the cross-linking reaction and the scaffolds degraded after only a few hours in aqueous medium at 37 °C. Glyceraldehyde and genipin were established as good options for cross-linking agents because of the low toxicity of these cross-linkers and the resistance to dissolution of the cross-linked fibers in cell culture medium at 37 °C. MG63 osteoblastic cells were grown on each of the cross-linked scaffolds. A proliferation assay showed that the cells proliferated as well or better on the cross-linked scaffolds than on traditional two-dimensional polystyrene culture plates.
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Affiliation(s)
- Kristin Sisson
- Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, USA
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