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Cheng KKW, Fingerhut L, Duncan S, Prajna NV, Rossi AG, Mills B. In vitro and ex vivo models of microbial keratitis: Present and future. Prog Retin Eye Res 2024; 102:101287. [PMID: 39004166 DOI: 10.1016/j.preteyeres.2024.101287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 07/09/2024] [Accepted: 07/10/2024] [Indexed: 07/16/2024]
Abstract
Microbial keratitis (MK) is an infection of the cornea, caused by bacteria, fungi, parasites, or viruses. MK leads to significant morbidity, being the fifth leading cause of blindness worldwide. There is an urgent requirement to better understand pathogenesis in order to develop novel diagnostic and therapeutic approaches to improve patient outcomes. Many in vitro, ex vivo and in vivo MK models have been developed and implemented to meet this aim. Here, we present current in vitro and ex vivo MK model systems, examining their varied design, outputs, reporting standards, and strengths and limitations. Major limitations include their relative simplicity and the perceived inability to study the immune response in these MK models, an aspect widely accepted to play a significant role in MK pathogenesis. Consequently, there remains a dependence on in vivo models to study this aspect of MK. However, looking to the future, we draw from the broader field of corneal disease modelling, which utilises, for example, three-dimensional co-culture models and dynamic environments observed in bioreactors and organ-on-a-chip scenarios. These remain unexplored in MK research, but incorporation of these approaches will offer further advances in the field of MK corneal modelling, in particular with the focus of incorporation of immune components which we anticipate will better recapitulate pathogenesis and yield novel findings, therefore contributing to the enhancement of MK outcomes.
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Affiliation(s)
- Kelvin Kah Wai Cheng
- Centre for Inflammation Research, Institute of Regeneration and Repair, University of Edinburgh, United Kingdom
| | - Leonie Fingerhut
- Centre for Inflammation Research, Institute of Regeneration and Repair, University of Edinburgh, United Kingdom
| | - Sheelagh Duncan
- Centre for Inflammation Research, Institute of Regeneration and Repair, University of Edinburgh, United Kingdom
| | - N Venkatesh Prajna
- Department of Cornea and Refractive Surgery Services, Aravind Eye Hospital and Postgraduate Institute of Ophthalmology, Madurai, Tamil Nadu, India
| | - Adriano G Rossi
- Centre for Inflammation Research, Institute of Regeneration and Repair, University of Edinburgh, United Kingdom
| | - Bethany Mills
- Centre for Inflammation Research, Institute of Regeneration and Repair, University of Edinburgh, United Kingdom.
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Zhou M, Archibeck ES, Feteih Y, Abubakr Y, O'Connell GD. Non-enzymatic glycation increases the failure risk of annulus fibrosus by predisposing the extrafibrillar matrix to greater stresses. Acta Biomater 2023; 168:223-234. [PMID: 37433360 DOI: 10.1016/j.actbio.2023.07.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 06/13/2023] [Accepted: 07/06/2023] [Indexed: 07/13/2023]
Abstract
Growing clinical evidence suggests a correlation between diabetes and more frequent and severe intervertebral disc failure, partially attributed to accelerated advanced glycation end-products (AGE) accumulation in the annulus fibrosus (AF) through non-enzymatic glycation. However, in vitro glycation (i.e., crosslinking) reportedly improved AF uniaxial tensile mechanical properties, contradicting clinical observations. Thus, this study used a combined experimental-computational approach to evaluate the effect of AGEs on anisotropic AF tensile mechanics, applying finite element models (FEMs) to complement experimental testing and examine difficult-to-measure subtissue-level mechanics. Methylglyoxal-based treatments were applied to induce three physiologically relevant AGE levels in vitro. Models incorporated crosslinks by adapting our previously validated structure-based FEM framework. Experimental results showed that a threefold increase in AGE content resulted in a ∼55% increase in AF circumferential-radial tensile modulus and failure stress and a 40% increase in radial failure stress. Failure strain was unaffected by non-enzymatic glycation. Adapted FEMs accurately predicted experimental AF mechanics with glycation. Model predictions showed that glycation increased stresses in the extrafibrillar matrix under physiologic deformations, which may increase tissue mechanical failure or trigger catabolic remodeling, providing insight into the relationship between AGE accumulation and increased tissue failure. Our findings also added to the existing literature regarding crosslinking structures, indicating that AGEs had a greater effect along the fiber direction, while interlamellar radial crosslinks were improbable in the AF. In summary, the combined approach presented a powerful tool for examining multiscale structure-function relationships with disease progression in fiber-reinforced soft tissues, which is essential for developing effective therapeutic measures. STATEMENT OF SIGNIFICANCE: Increasing clinical evidence correlates diabetes with premature intervertebral disc failure, likely due to advanced glycation end-products (AGE) accumulation in the annulus fibrosus (AF). However, in vitro glycation reportedly increases AF tensile stiffness and toughness, contradicting clinical observations. Using a combined experimental-computational approach, our work shows that increases in AF bulk tensile mechanical properties with glycation are achieved at the risk of exposing the extrafibrillar matrix to increased stresses under physiologic deformations, which may increase tissue mechanical failure or trigger catabolic remodeling. Computational results indicate that crosslinks along the fiber direction account for 90% of the increased tissue stiffness with glycation, adding to the existing literature. These findings provide insight into the multiscale structure-function relationship between AGE accumulation and tissue failure.
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Affiliation(s)
- Minhao Zhou
- Department of Mechanical Engineering, University of California, Berkeley, 2162 Etcheverry Hall, #1740, Berkeley, CA 94720-1740, USA
| | - Erin S Archibeck
- Department of Mechanical Engineering, University of California, Berkeley, 2162 Etcheverry Hall, #1740, Berkeley, CA 94720-1740, USA
| | - Yarah Feteih
- Department of Mechanical Engineering, University of California, Berkeley, 2162 Etcheverry Hall, #1740, Berkeley, CA 94720-1740, USA
| | - Yousuf Abubakr
- Department of Mechanical Engineering, University of California, Berkeley, 2162 Etcheverry Hall, #1740, Berkeley, CA 94720-1740, USA
| | - Grace D O'Connell
- Department of Mechanical Engineering, University of California, Berkeley, 5122 Etcheverry Hall, #1740, Berkeley, CA 94720-1740, USA; Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, USA.
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Huertas-Bello M, Cuéllar-Sáenz JA, Rodriguez CN, Cortés-Vecino JA, Navarrete ML, Avila MY, Koudouna E. A Pilot Study to Evaluate Genipin in Staphylococcus aureus and Pseudomonas aeruginosa Keratitis Models: Modulation of Pro-Inflammatory Cytokines and Matrix Metalloproteinases. Int J Mol Sci 2023; 24:ijms24086904. [PMID: 37108070 PMCID: PMC10138382 DOI: 10.3390/ijms24086904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 03/30/2023] [Accepted: 04/01/2023] [Indexed: 04/29/2023] Open
Abstract
Infectious keratitis is a vision-threatening microbial infection. The increasing antimicrobial resistance and the fact that severe cases often evolve into corneal perforation necessitate the development of alternative therapeutics for effective medical management. Genipin, a natural crosslinker, was recently shown to exert antimicrobial effects in an ex vivo model of microbial keratitis, highlighting its potential to serve as a novel treatment for infectious keratitis. This study aimed to evaluate the antimicrobial and anti-inflammatory effects of genipin in an in vivo model of Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) keratitis. Clinical scores, confocal microscopy, plate count, and histology were carried out to evaluate the severity of keratitis. To assess the effect of genipin on inflammation, the gene expression of pro- and anti-inflammatory factors, including matrix metalloproteinases (MMPs), were evaluated. Genipin treatment alleviated the severity of bacterial keratitis by reducing bacterial load and repressing neutrophil infiltration. The expression of interleukin 1B (IL1B), interleukin 6 (IL6), interleukin 8 (IL8), interleukin 15 (IL15), tumor necrosis factor-α (TNF-α), and interferon γ (IFNγ), as well as MMP2 and MMP9, were significantly reduced in genipin-treated corneas. Genipin promoted corneal proteolysis and host resistance to S. aureus and P. aeruginosa infection by suppressing inflammatory cell infiltration, regulating inflammatory mediators, and downregulating the expression of MMP2 and MMP9.
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Affiliation(s)
- Marcela Huertas-Bello
- Department of Ophthalmology, Faculty of Medicine, Bogota DC, Universidad Nacional de Colombia, Bogotá 111321, Colombia
| | - Jerson Andrés Cuéllar-Sáenz
- Grupo de Investigación Parasitología Veterinaria, Department of Animal Health, Faculty of Veterinary Medicine and Zootechnics, Bogota DC, Universidad Nacional de Colombia, Bogotá 111321, Colombia
| | - Cristian Nicolas Rodriguez
- Department of Microbiology, Faculty of Medicine, Bogota DC, Universidad Nacional de Colombia, Bogotá 111321, Colombia
| | - Jesús Alfredo Cortés-Vecino
- Grupo de Investigación Parasitología Veterinaria, Department of Animal Health, Faculty of Veterinary Medicine and Zootechnics, Bogota DC, Universidad Nacional de Colombia, Bogotá 111321, Colombia
| | - Myriam Lucia Navarrete
- Department of Microbiology, Faculty of Medicine, Bogota DC, Universidad Nacional de Colombia, Bogotá 111321, Colombia
| | - Marcel Yecid Avila
- Department of Ophthalmology, Faculty of Medicine, Bogota DC, Universidad Nacional de Colombia, Bogotá 111321, Colombia
| | - Elena Koudouna
- Department of Ophthalmology, Faculty of Medicine, Bogota DC, Universidad Nacional de Colombia, Bogotá 111321, Colombia
- Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff CF24 4HQ, UK
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Anumula L, Ramesh S, Kolaparthi VSK, Kirubakaran R, Karobari MI, Arora S, Saleh AA, Aldowah O, Messina P, Scardina GA. Role of Natural Cross Linkers in Resin-Dentin Bond Durability: A Systematic Review and Meta-Analysis. MATERIALS (BASEL, SWITZERLAND) 2022; 15:5650. [PMID: 36013786 PMCID: PMC9413318 DOI: 10.3390/ma15165650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 08/02/2022] [Accepted: 08/15/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND The role of endogenous Matrix Metallo Proteinases in resin dentin bond deterioration over time has been well documented. The present study aimed to systematically review the literature; in vitro and ex vivo studies that assessed the outcomes of natural cross-linkers for immediate and long-term tensile bond strength were included. METHODS The manuscript search was carried out in six electronic databases-PubMed/MEDLINE, LILACS, SciELO, Cochrane, Web of Science and DOAJ, without publication year limits. Only manuscripts in English (including the translated articles) were selected, and the last search was performed in December 2020. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was followed. RESULTS From the 128 potentially eligible studies, 48 full-text articles were assessed for eligibility. After eligibility assessment and exclusions, 14 studies were considered for systematic review and seven studies for meta-analysis. Amongst the selected studies for meta-analysis, three had a medium and four had a low risk of bias. CONCLUSIONS It was evidenced by the available data that Proanthocyanidin is the most efficient natural cross-linker to date, in preserving the bond strength even after ageing.
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Affiliation(s)
- Lavanya Anumula
- Department of Conservative Dentistry and Endodontics, Narayana Dental College and Hospital, Nellore 524003, Andra Pradesh, India
| | - Sindhu Ramesh
- Department of Conservative Dentistry and Endodontics, Saveetha Dental College and Hospital, Chennai 600077, Tamil Nadu, India
| | | | - Richard Kirubakaran
- Cochrane South Asia, BV Moses Centre for Evidence Informed Health Care and Health Policy, Christian Medical College, Vellore 632004, Tamil Nadu, India
| | - Mohmed Isaqali Karobari
- Department of Conservative Dentistry and Endodontics, Saveetha Dental College and Hospital, Chennai 600077, Tamil Nadu, India
- Conservative Dentistry Unit, School of Dental Sciences, Universiti Sains Malaysia, Health Campus, Kubang Kerian, Kota Bharu 16150, Malaysia
- Department of Restorative Dentistry & Endodontics, Faculty of Dentistry, University of Puthisastra, Phnom Penh 12211, Cambodia
| | - Suraj Arora
- Department of Restorative Dental Sciences, King Khalid University, P.O. Box 960, Abha 61421, Saudi Arabia
| | - Ahmed A. Saleh
- Department of Restorative Dental Sciences, King Khalid University, P.O. Box 960, Abha 61421, Saudi Arabia
| | - Omir Aldowah
- Prosthetic Dental Science Department, Faculty of Dentistry, Najran University, Najran 11001, Saudi Arabia
| | - Pietro Messina
- Department of Surgical, Oncological and Stomatological Disciplines, University of Palermo, 90133 Palermo, Italy
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Gerberich BG, Hannon BG, Brown DM, Read AT, Ritch MD, Schrader Echeverri E, Nichols L, Potnis C, Sridhar S, Toothman MG, Schwaner SA, Winger EJ, Huang H, Gershon GS, Feola AJ, Pardue MT, Prausnitz MR, Ethier CR. Evaluation of Spatially Targeted Scleral Stiffening on Neuroprotection in a Rat Model of Glaucoma. Transl Vis Sci Technol 2022; 11:7. [PMID: 35536721 PMCID: PMC9100482 DOI: 10.1167/tvst.11.5.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 03/14/2022] [Indexed: 11/25/2022] Open
Abstract
Purpose Scleral stiffening may protect against glaucomatous retinal ganglion cell (RGC) loss or dysfunction associated with ocular hypertension. Here, we assess the potential neuroprotective effects of two treatments designed to stiffen either the entire posterior sclera or only the sclera adjacent to the peripapillary sclera in an experimental model of glaucoma. Methods Rat sclerae were stiffened in vivo using either genipin (crosslinking the entire posterior sclera) or a regionally selective photosensitizer, methylene blue (stiffening only the juxtaperipapillary region surrounding the optic nerve). Ocular hypertension was induced using magnetic microbeads delivered to the anterior chamber. Morphological and functional outcomes, including optic nerve axon count and appearance, retinal thickness measured by optical coherence tomography, optomotor response, and electroretinography traces, were assessed. Results Both local (juxtaperipapillary) and global (whole posterior) scleral stiffening treatments were successful at increasing scleral stiffness, but neither provided demonstrable neuroprotection in hypertensive eyes as assessed by RGC axon counts and appearance, optomotor response, or electroretinography. There was a weak indication that scleral crosslinking protected against retinal thinning as assessed by optical coherence tomography. Conclusions Scleral stiffening was not demonstrated to be neuroprotective in ocular hypertensive rats. We hypothesize that the absence of benefit may in part be due to RGC loss associated with the scleral stiffening agents themselves (mild in the case of genipin, and moderate in the case of methylene blue), negating any potential benefit of scleral stiffening. Translational Relevance The development of scleral stiffening as a neuroprotective treatment will require the identification of better tolerated stiffening protocols and further preclinical testing.
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Affiliation(s)
- Brandon G. Gerberich
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Bailey G. Hannon
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Dillon M. Brown
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - A. Thomas Read
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Matthew D. Ritch
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Elisa Schrader Echeverri
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Lauren Nichols
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Cahil Potnis
- Center for Visual and Neurocognitive Rehabilitation, Atlanta Veteran Affairs Healthcare System, Atlanta, GA, USA
| | - Sreesh Sridhar
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Maya G. Toothman
- College of Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Stephen A. Schwaner
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
- Exponent, Inc., Biomechanics Practice, Atlanta, GA, USA
| | - Erin J. Winger
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Hannah Huang
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Gabby S. Gershon
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Andrew J. Feola
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
- Center for Visual and Neurocognitive Rehabilitation, Atlanta Veteran Affairs Healthcare System, Atlanta, GA, USA
| | - Machelle T. Pardue
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
- Center for Visual and Neurocognitive Rehabilitation, Atlanta Veteran Affairs Healthcare System, Atlanta, GA, USA
| | - Mark R. Prausnitz
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - C. Ross Ethier
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
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Donovan C, Koudouna E, Margo CE, Avila MY, Espana EM. Genipin Delays Corneal Stromal Enzymatic Digestion. Transl Vis Sci Technol 2021; 10:25. [PMID: 34424287 PMCID: PMC8394563 DOI: 10.1167/tvst.10.9.25] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To evaluate the use of genipin in delaying enzymatic digestion of corneal stroma. Methods Human corneal stromal tissue was treated with genipin, a known chemical crosslinker, and then along with control tissue was subjected to enzymatic digestion with collagenase. The effects of genipin treatment in retarding stromal digestion were analyzed with phase contrast microscopy, a protein quantification assay, second harmonic generation imaging, and transmission electron microscopy. Results Genipin increased stromal resistance to enzymatic digestion when compared with untreated stroma. A morphologic analysis and protein quantification showed increased stromal resistance to enzymatic digestion once stromal tissue was treated with genipin. Second harmonic generation imaging revealed persistent fibrillar collagen signaling in genipin-treated tissue in contrast with untreated tissue suggesting that genipin retards collagenolysis. Conclusions Genipin increases stromal resistance to enzymatic digestion in controlled experiments as demonstrated by protein quantification studies and through morphologic imaging. Translational Relevance This study explores the novel use of genipin in delaying enzymatic stromal digestion. Delaying stromal melting in the setting of corneal infectious or autoimmune keratitis can potentially decrease clinical morbidity.
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Affiliation(s)
- Christopher Donovan
- Department of Ophthalmology, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
| | - Elena Koudouna
- Department of Ophthalmology, School of Medicine, Universidad Nacional de Colombia, Hospital Universitario Nacional, Bogota, Colombia.,Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
| | - Curtis E Margo
- Department of Pathology and Cell Biology, Morsani College of Medicine, University of South Florida, Tampa, FL, USA.,Department of Ophthalmology, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
| | - Marcel Y Avila
- Department of Ophthalmology, School of Medicine, Universidad Nacional de Colombia, Hospital Universitario Nacional, Bogota, Colombia
| | - Edgar M Espana
- Department of Ophthalmology, Morsani College of Medicine, University of South Florida, Tampa, FL, USA.,Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
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Koudouna E, Huertas-Bello M, Rodriguez CN, Consuelo Henao S, Navarrete ML, Avila MY. Genipin in an Ex Vivo Corneal Model of Bacterial and Fungal Keratitis. Transl Vis Sci Technol 2021; 10:31. [PMID: 34436544 PMCID: PMC8399543 DOI: 10.1167/tvst.10.9.31] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 07/06/2021] [Indexed: 01/04/2023] Open
Abstract
Purpose To determine whether genipin (a natural crosslinker) could reduce the colonization and proliferation of bacteria and fungi in an ex vivo model of corneal infection. Methods This study, using an ex vivo model of bacterial and fungal keratitis, investigated the antimicrobial efficacy of genipin crosslinking. Excised corneoscleral buttons were wounded by scalpel incision and subsequently infected with Staphylococcus aureus, Pseudomonas aeruginosa, or Candida albicans. After inoculation, corneas were treated with genipin for 24 hours at 37°C. Histologic examinations were carried out, and the number of viable colony-forming units (CFU)/cornea was determined. Results Genipin exerts bactericidal action against S. aureus and P. aeruginosa, as well as fungicidal action against C. albicans and significantly reduced the CFU compared to contralateral eyes that received saline treatment (P < 0.05). Conclusions These data identify genipin as a novel ocular antimicrobial agent that has the potential to be incorporated into the therapeutic armamentarium against microbial keratitis. Translational Relevance This study provided evidence for the antimicrobial and antifungal properties of genipin as an alternative crosslinker that could be used in the management of infectious keratitis.
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Affiliation(s)
- Elena Koudouna
- Department of Ophthalmology, Faculty of Medicine, Bogota DC, Universidad Nacional de Colombia, Bogota Colombia
- Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales, UK
| | - Marcela Huertas-Bello
- Department of Ophthalmology, Faculty of Medicine, Bogota DC, Universidad Nacional de Colombia, Bogota Colombia
| | - Cristian Nicolas Rodriguez
- Department of Microbiology, Faculty of Medicine, Bogota DC, Universidad Nacional de Colombia, Bogota Colombia
| | - Sandra Consuelo Henao
- Department of Microbiology, Faculty of Medicine, Bogota DC, Universidad Nacional de Colombia, Bogota Colombia
| | - Myriam Lucia Navarrete
- Department of Microbiology, Faculty of Medicine, Bogota DC, Universidad Nacional de Colombia, Bogota Colombia
| | - Marcel Yecid Avila
- Department of Ophthalmology, Faculty of Medicine, Bogota DC, Universidad Nacional de Colombia, Bogota Colombia
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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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Song W, Cheng Y, Yan X, Yang S. Long-Term Study of Corneal Stroma and Endothelium on Structure and Cells After Genipin Treatment of Rabbit Corneas. Transl Vis Sci Technol 2021; 10:9. [PMID: 34529024 PMCID: PMC8447043 DOI: 10.1167/tvst.10.5.9] [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 study the long-term safety of genipin treatment using a vacuum device with or without epithelial cells at different crosslinking times. Methods Twenty-five healthy New Zealand white rabbits were separated into five treatment groups: 0.25% genipin with epithelial cells for 5 minutes (G1), 0.25% genipin without epithelial cells for 5 minutes (G2), 0.25% genipin without epithelial cells for 10 minutes (G3), ultraviolet A–riboflavin collagen crosslinking (UVA), and controls (C). Before and 2, 4, 6, and 8 weeks after crosslinking treatment, anterior segment optical coherence tomography (ASOCT), in vivo confocal microscopy (IVCM), and the Pentacam system were used to evaluate the right eyes. Results A demarcation line (DL) was observed in the corneal stroma in the G2, G3, and UVA groups. The DL depths in the G2 and G3 groups were stable but decreased in the UVA group over time. The density of keratocytes in these groups increased. Endothelial cell density was decreased in the UVA group. There were no differences in the endothelium before and after treatment in the G1, G2, G3, and C groups. The densitometry, as determined using the Pentacam system, significantly increased in the G2, G3, and UVA groups and was positively correlated with keratocyte densities. Conclusions A vacuum ring assisting local genipin immersion crosslinking without corneal epithelium can activate the keratocytes in the corneal stroma and was safe enough for the thin cornea. Translational Relevance Genipin can not only crosslink the collagen fibers but also activate the keratocytes and even may promote collagen fiber secretion.
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Affiliation(s)
- Wenjing Song
- Department of Ophthalmology, Peking University First Hospital, Beijing, China
| | - Yu Cheng
- Department of Ophthalmology, Peking University First Hospital, Beijing, China
| | - Xiaoming Yan
- Department of Ophthalmology, Peking University First Hospital, Beijing, China
| | - Songlin Yang
- Department of Ophthalmology, Peking University First Hospital, Beijing, China
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10
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Yu Y, Xu S, Li S, Pan H. Genipin-cross-linked hydrogels based on biomaterials for drug delivery: a review. Biomater Sci 2021; 9:1583-1597. [PMID: 33443245 DOI: 10.1039/d0bm01403f] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Genipin is a naturally occurring nontoxic cross-linker, which has been widely used for drug delivery due to its excellent biocompatibility, admirable biodegradability and stable cross-linked attributes. These advantages led to its extensive application in the fabrication of hydrogels for drug delivery. This review describes the physicochemical characteristics and pharmacological activities of genipin and attempts to elucidate the detailed mechanisms of the cross-linking reaction between genipin and biomaterials. The current article entails a general review of the different biomaterials cross-linked by genipin: chitosan and its derivatives, collagen, gelatin, etc. The genipin-cross-linked hydrogels for various pharmaceutical applications, including ocular drug delivery, buccal drug delivery, oral drug delivery, anti-inflammatory drug delivery, and antibiotic and antifungal drug delivery, are reported. Finally, the future research directions and challenges of genipin-cross-linked hydrogels for pharmaceutical applications are also discussed in this review.
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Affiliation(s)
- Yibin Yu
- School of Pharmacy, Liaoning University, Shenyang 110036, China. and Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, 325001, China
| | - Shuo Xu
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Sanming Li
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Hao Pan
- School of Pharmacy, Liaoning University, Shenyang 110036, China.
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11
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Pang Z, Wang L, Zhang C, Wang J, Gao Z, Li Z, Hao J, Mu G. Effects of hydrogen peroxide solution on the biomechanics of porcine cornea. Eur J Ophthalmol 2021; 31:2227-2232. [PMID: 33626917 DOI: 10.1177/1120672121996641] [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] [Indexed: 11/15/2022]
Abstract
OBJECTIVES To determine the biomechanical changes of porcine corneas after the application of hydrogen peroxide(H2O2) solution. METHODS Fifty-five porcine eyeballs with similar sizes were divided into 11 groups based on the H2O2 application. The eyeballs were treated with the following concentrations of H2O2 solution: 1 mol/L, 500 mmol/L, 250 mmol/L, 125 mmol/L, 62.5 mmol/L, 31.25 mmol/L, 15.63 mmol/L, 7.81 mmol/L, 3.91 mmol/L, 0.9% saline, or blank. The eyeballs were immersed into the solution for 30 min. The biomechanics of each cornea in the different groups was determined soon after the indentation and tensile tests. We calculated the average Young's modulus of the different groups to determine the effects of H2O2 solution on porcine corneas. The comparison between the groups was conducted using ANOVA analysis. Moreover, the safety of each concentration of H2O2 solution on the corneal tissues was determined by histopathological examination. RESULTS The Young's modulus was significantly different among all the groups (p = 0.003). The modulus was the highest in the group treated with 3.91 mmol/L H2O2 and it was significantly different from that in the group treated with 0.9% saline or the blank group, for both the indentation and tensile tests. Histopathological examination showed that H2O2 at a concentration of ⩾62.5 mmol/L damaged the epithelium, stroma, or both, while H2O2 at a concentration ⩽31.25 mmol/L did not change the morphology of the epithelium or stroma. CONCLUSIONS Treatment with 3.91 mmol/L H2O2 solution can safely and effectively increase the biomechanical strength of the cornea.
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Affiliation(s)
- Zuoxiang Pang
- Department of Ophthalmology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China.,Department of Ophthalmology, Weifang No. 2 People's Hospital, Weifang, Shandong, China
| | - Lijun Wang
- Department of Ophthalmology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China.,Department of Ophthalmology, Binzhou Medical University Hospital, Binzhou, Shandong, China
| | - Chunxiao Zhang
- Department of Ophthalmology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Jia Wang
- Aier Eye Hospital Group, Liaocheng Aier Eye Hospital, Liaocheng, Shandong, China
| | - Zhipeng Gao
- Department of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, China
| | - Zhiwei Li
- Department of Ophthalmology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Jiangdong Hao
- Department of Ophthalmology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Guoying Mu
- Department of Ophthalmology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
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12
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Atalay E, Özalp O, Yıldırım N. Advances in the diagnosis and treatment of keratoconus. Ther Adv Ophthalmol 2021; 13:25158414211012796. [PMID: 34263132 PMCID: PMC8246497 DOI: 10.1177/25158414211012796] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 04/07/2021] [Indexed: 01/31/2023] Open
Abstract
Keratoconus had traditionally been considered a rare disease at a time when the imaging technology was inept in detecting subtle manifestations, resulting in more severe disease at presentation. The increased demand for refractive surgery in recent years also made it essential to more effectively detect keratoconus before attempting any ablative procedure. Consequently, the armamentarium of tools that can be used to diagnose and treat keratoconus has significantly expanded. The advances in imaging technology have allowed clinicians and researchers alike to visualize the cornea layer by layer looking for any early changes that might be indicative of keratoconus. In addition to the conventional geometrical evaluation, efforts are also underway to enable spatially resolved corneal biomechanical evaluation. Artificial intelligence has been exploited in a multitude of ways to enhance diagnostic efficiency and to guide treatment. As for treatment, corneal cross-linking treatment remains the mainstay preventive approach, yet the current main focus of research is on increasing oxygen availability and developing new strategies to improve riboflavin permeability during the procedure. Some new combined protocols are being proposed to simultaneously halt keratoconus progression and correct refractive error. Bowman layer transplantation and additive keratoplasty are newly emerging alternatives to conventional keratoplasty techniques that are used in keratoconus surgery. Advances in tissue engineering and regenerative therapy might bring new perspectives for treatment at the cellular level and hence obviate the need for invasive surgeries. In this review, we describe the advances in the diagnosis and treatment of keratoconus primarily focusing on newly emerging approaches and strategies.
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Affiliation(s)
- Eray Atalay
- Department of Ophthalmology, Medical School, Eskişehir Osmangazi University, Meşelik Kampüsü, Odunpazarı, Eskişehir 26040, Turkey
| | - Onur Özalp
- Department of Ophthalmology, Medical School, Eskişehir Osmangazi University, Eskişehir, Turkey
| | - Nilgün Yıldırım
- Department of Ophthalmology, Medical School, Eskişehir Osmangazi University, Eskişehir, Turkey
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13
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Hannon BG, Luna C, Feola AJ, Ritch MD, Read AT, Stinnett SS, Vo H, Pardue MT, Gonzalez P, Ethier CR. Assessment of Visual and Retinal Function Following In Vivo Genipin-Induced Scleral Crosslinking. Transl Vis Sci Technol 2020; 9:8. [PMID: 32974080 PMCID: PMC7488211 DOI: 10.1167/tvst.9.10.8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Accepted: 07/13/2020] [Indexed: 01/25/2023] Open
Abstract
Purpose Genipin has been proposed as a possible neuroprotective therapy in myopia and glaucoma. Here, we aim to determine the effects of prolonged genipin-induced scleral stiffening on visual function. Methods Eyes from Brown Norway rats were treated in vivo with either a single 15 mM genipin retrobulbar injection or sham retrobulbar injection and were compared to naïve eyes. Intraocular pressure, optomotor response, and electroretinograms were repeatedly measured over 4 weeks following retrobulbar injections to determine visual and retinal function. At 4 weeks, we quantified retinal ganglion cell axon counts. Finally, molecular changes in gene and protein expression were analyzed via real-time polymerase chain reaction (RT-PCR) and proteomics. Results Retrobulbar injection of genipin did not affect intraocular pressure (IOP) or retinal function, nor have a sustained impact on visual function. Although genipin-treated eyes had a small decrease in retinal ganglion cell axon counts compared to contralateral sham-treated eyes (−8,558 ± 18,646; mean ± SD), this was not statistically significant (P = 0.206, n = 9). Last, we did not observe any changes in gene or protein expression due to genipin treatment. Conclusions Posterior scleral stiffening with a single retrobulbar injection of 15 mM genipin causes no sustained deficits in visual or retinal function or at the molecular level in the retina and sclera. Retinal ganglion cell axon morphology appeared normal. Translational Significance These results support future in vivo studies to determine the efficacy of genipin-induced posterior scleral stiffening to help treat ocular diseases, like myopia and glaucoma.
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Affiliation(s)
- Bailey G Hannon
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Coralia Luna
- Duke Ophthalmology, Duke University School of Medicine, Durham, NC, USA
| | - Andrew J Feola
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA.,Center for Visual and Neurocognitive Rehabilitation, Atlanta Veteran Affairs Healthcare System, Atlanta, GA, USA
| | - Matthew D Ritch
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - A Thomas Read
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Sandra S Stinnett
- Duke Ophthalmology, Duke University School of Medicine, Durham, NC, USA.,Department of Biostatistics and Bioinformatics, Duke University, Durham, NC, USA
| | - Harrison Vo
- Center for Visual and Neurocognitive Rehabilitation, Atlanta Veteran Affairs Healthcare System, Atlanta, GA, USA
| | - Machelle T Pardue
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA.,Center for Visual and Neurocognitive Rehabilitation, Atlanta Veteran Affairs Healthcare System, Atlanta, GA, USA
| | - Pedro Gonzalez
- Duke Ophthalmology, Duke University School of Medicine, Durham, NC, USA
| | - C Ross Ethier
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA.,Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
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14
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Kaczmarek B, Mazur O. Collagen-Based Materials Modified by Phenolic Acids-A Review. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E3641. [PMID: 32824538 PMCID: PMC7476000 DOI: 10.3390/ma13163641] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/13/2020] [Accepted: 08/14/2020] [Indexed: 02/06/2023]
Abstract
Collagen-based biomaterials constitute one of the most widely studied types of materials for biomedical applications. Low thermal and mechanical parameters are the main disadvantages of such structures. Moreover, they present low stability in the case of degradation by collagenase. To improve the properties of collagen-based materials, different types of cross-linkers have been researched. In recent years, phenolic acids have been studied as collagen modifiers. Mainly, tannic acid has been tested for collagen modification as it interacts with a polymeric chain by strong hydrogen bonds. When compared to pure collagen, such complexes show both antimicrobial activity and improved physicochemical properties. Less research reporting on other phenolic acids has been published. This review is a summary of the present knowledge about phenolic acids (e.g., tannic, ferulic, gallic, and caffeic acid) application as collagen cross-linkers. The studies concerning collagen-based materials with phenolic acids are summarized and discussed.
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Affiliation(s)
- Beata Kaczmarek
- Department of Biomaterials and Cosmetics Chemistry, Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarin 7, 87-100 Toruń, Poland;
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15
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Adamiak K, Sionkowska A. Current methods of collagen cross-linking: Review. Int J Biol Macromol 2020; 161:550-560. [PMID: 32534089 DOI: 10.1016/j.ijbiomac.2020.06.075] [Citation(s) in RCA: 130] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 06/04/2020] [Accepted: 06/08/2020] [Indexed: 01/16/2023]
Abstract
This review provides a report on cross-linking methods used for collagen modifications. Collagen materials have attracted significant academic interest due to its biological properties in native state. However, in many cases the mechanical properties and degradation rate should be tailored to especial biomedical and cosmetic applications. In the proposed review paper, the structure, preparation, and properties of several collagen based materials have been discussed in general, and detailed examples of collagen cross-linking methods have been drawn from scientific literature and practical work. Both, physical and chemical methods of improvement of collagenous materials have been reviewed. In the review paper the cross-linking with glutaraldehyde, genipin, EDC-NHS, dialdehyde starch, chitosan, temperature, UV light and enzyme has been discussed. A critical comparison of currently available cross-linking methods has been shown.
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Affiliation(s)
| | - Alina Sionkowska
- Nicolaus Copernicus University in Torun, Faculty of Chemistry, Department of Biomaterials and Cosmetics Chemistry, Gagarin 7 street, 87-100 Torun, Poland.
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16
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Sun X, Chen D, Liu X, Yan X, Wu Y. Effect of enzyme-induced collagen crosslinking on porcine sclera. Biochem Biophys Res Commun 2020; 528:134-139. [PMID: 32451081 DOI: 10.1016/j.bbrc.2020.05.078] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 05/11/2020] [Indexed: 01/25/2023]
Abstract
This study aims to evaluate the effect of a new type of collagen crosslinking (CXL) mediated by microbial transglutaminases (Tgases) on sclera. Porcine eyes were divided into two groups according to the different crosslinking procedures used: the double-sided CXL group (D-CXL group) and the single-sided CXL group (S-CXL group). In the D-CXL group, 4.0 × 14.0 mm scleral strips harvested from 40 porcine eyeballs were incubated with 1 U/ml Tgases for 30 min at 37 °C. Parallel scleral strips from the same eyeball were incubated with PBS under the same conditions as the controls. In the S-CXL group, 80 whole globes were directly incubated with 1 U/ml Tgases and PBS as the controls for 30 min at 37 °C. After incubation, 4.0 × 14.0 mm scleral strips were cut from each eyeball. Biomechanical testing and light microscopy were used. In the D-CXL group, the general elastic modulus of the Tgases-treated scleral strips was 14.89 ± 6.05 MPa, and the controls was 6.72 ± 2.58 MPa, indicating an increase of 121% with Tgases treatment. In the S-CXL group, the general elastic modulus of the Tgases-treated scleral strips was 12.88 ± 4.29 MPa, and the controls was 7.00 ± 2.45 MPa, indicating an increase of 84% with Tgases treatment. In both the D-CXL and S-CXL groups, significant increases in scleral rigidity were observed compared to that of the respective controls (P < 0.05). The histology indicated increased collagen bundle density, decreased interfibrillar spaces and increased interlamellar spaces after CXL. In conclusion, scleral collagen crosslinking mediated by Tgases produced a significant increase in biomechanical strength.
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Affiliation(s)
- Xiaona Sun
- Department of Ophthalmology, Peking University First Hospital, Peking University, Beijing, 100034, China
| | - Duo Chen
- School of Biological Science and Medical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beihang University, Beijing, 100191, China; Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing 100083, China
| | - Xiaoyu Liu
- School of Biological Science and Medical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beihang University, Beijing, 100191, China; Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing 100083, China
| | - Xiaoming Yan
- Department of Ophthalmology, Peking University First Hospital, Peking University, Beijing, 100034, China.
| | - Yuan Wu
- Department of Ophthalmology, Peking University First Hospital, Peking University, Beijing, 100034, China.
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17
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Kočí Z, Sridharan R, Hibbitts AJ, Kneafsey SL, Kearney CJ, O'Brien FJ. The Use of Genipin as an Effective, Biocompatible, Anti-Inflammatory Cross-Linking Method for Nerve Guidance Conduits. ACTA ACUST UNITED AC 2020; 4:e1900212. [PMID: 32293152 DOI: 10.1002/adbi.201900212] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 12/06/2019] [Indexed: 11/09/2022]
Abstract
A number of natural polymer biomaterial-based nerve guidance conduits (NGCs) are developed to facilitate repair of peripheral nerve injuries. Cross-linking ensures mechanical integrity and desired degradation properties of the NGCs; however, common methods such as formaldehyde are associated with cellular toxicity. Hence, there is an unmet clinical need for alternative nontoxic cross-linking agents. In this study, collagen-based NGCs with a collagen/chondroitin sulfate luminal filler are used to study the effect of cross-linking on mechanical and structural properties, degradation, biocompatibility, and immunological response. A simplified manufacturing method of genipin cross-linking is developed, by incorporating genipin into solution prior to freeze-drying the NGCs. This leads to successful cross-linking as demonstrated by higher cross-linking degree and similar tensile strength of genipin cross-linked conduits compared to formaldehyde cross-linked conduits. Genipin cross-linking also preserves NGC macro and microstructure as observed through scanning electron microscopy and spectral analysis. Most importantly, in vitro cell studies show that genipin, unlike the formaldehyde cross-linked conduits, supports the viability of Schwann cells. Moreover, genipin cross-linked conduits direct macrophages away from a pro-inflammatory and toward a pro-repair state. Overall, genipin is demonstrated to be an effective, safe, biocompatible, and anti-inflammatory alternative to formaldehyde for cross-linking clinical grade NGCs.
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Affiliation(s)
- Zuzana Kočí
- Tissue Engineering Research Group (TERG), Department of Anatomy and Regenerative Medicine, Royal College of Surgeons in Ireland, Dublin 2, D02YN77, Ireland.,Trinity Centre for Biomedical Engineering (TCBE), Trinity College Dublin, Dublin, D02PN40, Ireland.,Advanced Materials and Bioengineering Research (AMBER) Centre, Royal College of Surgeons in Ireland and Trinity College Dublin, Dublin, D02YN77, Ireland
| | - Rukmani Sridharan
- Tissue Engineering Research Group (TERG), Department of Anatomy and Regenerative Medicine, Royal College of Surgeons in Ireland, Dublin 2, D02YN77, Ireland.,Trinity Centre for Biomedical Engineering (TCBE), Trinity College Dublin, Dublin, D02PN40, Ireland.,Advanced Materials and Bioengineering Research (AMBER) Centre, Royal College of Surgeons in Ireland and Trinity College Dublin, Dublin, D02YN77, Ireland
| | - Alan J Hibbitts
- Tissue Engineering Research Group (TERG), Department of Anatomy and Regenerative Medicine, Royal College of Surgeons in Ireland, Dublin 2, D02YN77, Ireland.,Trinity Centre for Biomedical Engineering (TCBE), Trinity College Dublin, Dublin, D02PN40, Ireland.,Advanced Materials and Bioengineering Research (AMBER) Centre, Royal College of Surgeons in Ireland and Trinity College Dublin, Dublin, D02YN77, Ireland
| | - Simone L Kneafsey
- Tissue Engineering Research Group (TERG), Department of Anatomy and Regenerative Medicine, Royal College of Surgeons in Ireland, Dublin 2, D02YN77, Ireland.,Trinity Centre for Biomedical Engineering (TCBE), Trinity College Dublin, Dublin, D02PN40, Ireland.,Advanced Materials and Bioengineering Research (AMBER) Centre, Royal College of Surgeons in Ireland and Trinity College Dublin, Dublin, D02YN77, Ireland
| | - Cathal J Kearney
- Tissue Engineering Research Group (TERG), Department of Anatomy and Regenerative Medicine, Royal College of Surgeons in Ireland, Dublin 2, D02YN77, Ireland.,Trinity Centre for Biomedical Engineering (TCBE), Trinity College Dublin, Dublin, D02PN40, Ireland.,Advanced Materials and Bioengineering Research (AMBER) Centre, Royal College of Surgeons in Ireland and Trinity College Dublin, Dublin, D02YN77, Ireland
| | - Fergal J O'Brien
- Tissue Engineering Research Group (TERG), Department of Anatomy and Regenerative Medicine, Royal College of Surgeons in Ireland, Dublin 2, D02YN77, Ireland.,Trinity Centre for Biomedical Engineering (TCBE), Trinity College Dublin, Dublin, D02PN40, Ireland.,Advanced Materials and Bioengineering Research (AMBER) Centre, Royal College of Surgeons in Ireland and Trinity College Dublin, Dublin, D02YN77, Ireland
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18
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Song W, Tang Y, Qiao J, Li H, Rong B, Yang S, Wu Y, Yan X. The Short-Term Safety Evaluation of Corneal Crosslinking Agent-Genipin. Ophthalmic Res 2019; 62:141-149. [PMID: 31112970 DOI: 10.1159/000499571] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 03/13/2019] [Indexed: 11/19/2022]
Abstract
BACKGROUND Genipin (GP) is a safe method for corneal crosslinking, even for very thin corneas. However, there have been no reports on the optimal GP concentration range to use in vivo for corneal crosslinking. OBJECTIVES To investigate the safety of corneal crosslinking after a 24-h incubation with different concentrations of GP. METHODS Twenty New Zealand white rabbits were divided into a phosphate-buffered saline (PBS) group, 0.2% GP crosslinking (GP-CXL) group, 0.25% GP-CXL group, and 0.3% GP-CXL group. Before and after surgery, the operated eyes of each group were characterized by confocal microscopy, and corneal buttons were excised for endothelium staining and electron microscopy. RESULTS The keratocyte structures in each GP group appeared to be similar to those in the PBS group. Through the confocal microscopy, the changes in corneal endothelial cell density also did not significantly differ among groups. There was a significant difference in apoptosis between the 0.3% GP-CXL and PBS groups (p < 0.05) and between the 0.3% GP-CXL and 0.25% GP-CXL groups (p < 0.05), but there were no significant differences between the 0.2 and 0.25% GP-CXL groups compared to the PBS group. Transmission electron microscopy showed endothelial cell damage in the 0.3% GP-CXL group, with minimal endothelial cell damage in the other groups. CONCLUSIONS Treatment of rabbit corneas with ≤0.25% GP resulted in minimal toxicity to keratocytes and endothelial cells, suggesting that it is a safe crosslinking agent at those concentrations.
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Affiliation(s)
- Wenjing Song
- Department of Ophthalmology, Peking University First Hospital, Beijing, China
| | - Yun Tang
- Department of Ophthalmology, Peking University First Hospital, Beijing, China
| | - Jing Qiao
- Department of Ophthalmology, Peking University First Hospital, Beijing, China
| | - Haili Li
- Department of Ophthalmology, Peking University First Hospital, Beijing, China
| | - Bei Rong
- Department of Ophthalmology, Peking University First Hospital, Beijing, China
| | - Songlin Yang
- Department of Ophthalmology, Peking University First Hospital, Beijing, China
| | - Yuan Wu
- Department of Ophthalmology, Peking University First Hospital, Beijing, China
| | - Xiaoming Yan
- Department of Ophthalmology, Peking University First Hospital, Beijing, China,
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19
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Gao M, Wang Y, He Y, Li Y, Wu Q, Yang G, Zhou Y, Wu D, Bao J, Bu H. Comparative evaluation of decellularized porcine liver matrices crosslinked with different chemical and natural crosslinking agents. Xenotransplantation 2018; 26:e12470. [PMID: 30414216 DOI: 10.1111/xen.12470] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 10/05/2018] [Accepted: 10/19/2018] [Indexed: 02/05/2023]
Affiliation(s)
- Mengyu Gao
- Laboratory of Pathology, Key Laboratory of Transplant Engineering and Immunology; NHFPC; West China Hospital, Sichuan University; Chengdu China
| | - Yujia Wang
- Laboratory of Pathology, Key Laboratory of Transplant Engineering and Immunology; NHFPC; West China Hospital, Sichuan University; Chengdu China
| | - Yuting He
- Laboratory of Pathology, Key Laboratory of Transplant Engineering and Immunology; NHFPC; West China Hospital, Sichuan University; Chengdu China
| | - Yi Li
- Laboratory of Pathology, Key Laboratory of Transplant Engineering and Immunology; NHFPC; West China Hospital, Sichuan University; Chengdu China
| | - Qiong Wu
- Laboratory of Pathology, Key Laboratory of Transplant Engineering and Immunology; NHFPC; West China Hospital, Sichuan University; Chengdu China
| | - Guang Yang
- Experimental Animal Center; West China Hospital, Sichuan University; Chengdu China
| | - Yanyan Zhou
- Laboratory of Pathology, Key Laboratory of Transplant Engineering and Immunology; NHFPC; West China Hospital, Sichuan University; Chengdu China
| | - Diwei Wu
- Laboratory of Pathology, Key Laboratory of Transplant Engineering and Immunology; NHFPC; West China Hospital, Sichuan University; Chengdu China
| | - Ji Bao
- Laboratory of Pathology, Key Laboratory of Transplant Engineering and Immunology; NHFPC; West China Hospital, Sichuan University; Chengdu China
| | - Hong Bu
- Laboratory of Pathology, Key Laboratory of Transplant Engineering and Immunology; NHFPC; West China Hospital, Sichuan University; Chengdu China
- Department of Pathology; West China Hospital, Sichuan University; Chengdu China
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20
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Gharaibeh AM, Saez V, Garcia N, Bataille L, Alió JL. Optimizing Genipin Concentration for Corneal Collagen Cross-Linking: An ex vivo Study. Ophthalmic Res 2018; 60:100-108. [PMID: 29804113 DOI: 10.1159/000487950] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 02/25/2018] [Indexed: 11/19/2022]
Abstract
PURPOSE Studying genipin variable concentrations, treatment durations, and delivery methods as a substance to increase corneal stiffness by inducing corneal collagen cross-linking (CXL). MATERIALS AND METHODS 100 bovine corneas treated with different genipin concentrations (0.1, 0.5, and 1%) and treatment durations (15 min, 40 min, 2 h, and 3 days) through different delivery methods compared to 10 controls treated with riboflavin/UV. Histology examination, enzymatic digestion with collagenase and thermal differential scanning calorimetry were performed on the different samples. RESULTS Bovine corneas soaked in 0.5% genipin morphologically showed 4.7% CXL in comparison to 5.6% in controls (p < 0.05). Corneas treated with topical 0.5% genipin, by a 140-µL drop applied hourly for 2 h, showed 7% corneal CXL. Corneas treated with topical genipin 0.5% for 30 min, 1 and 2 h showed 54 ± 6, 40 ± 7, and 39 ± 9% enzymatic degradation, respectively, in comparison to controls (74%). Corneas treated with 0.5% genipin for 1, 2, and 8 h showed higher thermal denaturation resistance (Td values of 64.9 ± 0.3, 64.7 ± 0.0 and 67.3 ± 0.9), respectively, in comparison to the control group (64.6 ± 0.5) (p < 0.05). CONCLUSIONS Genipin 0.5%, in a 140-µL drop applied hourly for 2 h, showed better potential to enhance corneal stiffness and stability through inducing CXL.
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Affiliation(s)
- Almutez M Gharaibeh
- Faculty of Medicine, The University of Jordan, Amman, Jordan.,Vissum Instituto Oftalmológico de Alicante, Universidad Miguel Hernández, Alicante, Spain
| | - Virginia Saez
- Tecnalia Research and Innovation - Health Division, San Sebastián, Spain
| | - Nerea Garcia
- Tecnalia Research and Innovation - Health Division, San Sebastián, Spain
| | - Laurent Bataille
- Vissum Instituto Oftalmológico de Alicante, Universidad Miguel Hernández, Alicante, Spain
| | - Jorge L Alió
- Vissum Instituto Oftalmológico de Alicante, Universidad Miguel Hernández, Alicante, Spain.,Division of Ophthalmology, Universidad Miguel Hernández, Alicante, Spain
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21
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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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Liu TX, Wang Z. Biomechanics of sclera crosslinked using genipin in rabbit. Int J Ophthalmol 2017; 10:355-360. [PMID: 28393024 DOI: 10.18240/ijo.2017.03.05] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 10/31/2016] [Indexed: 11/23/2022] Open
Abstract
AIM To strengthen the biomechanics of collagen by crosslinking rabbit scleral collagen with genipin to develop a new therapy for preventing myopic progression. METHODS Ten New Zealand rabbits were treated with 0.5 mmol/L genipin injected into the sub-Tenon's capsule in the right eyes. Untreated contralateral eyes served as the control. The treated area was cut into scleral strips measuring 4.0 mm×10.0 mm for stress-strain measurements (n=5). The remaining five treated eyes were prepared for histological examination. RESULTS Compared to the untreated scleral strips, the genipin-crosslinked scleral strips showed that the ultimate stress and Young's modulus at 10% strain were increased by the amplitude of 130% and 303% respectively, ultimate strain was decreased by 24%. There had no α-smooth muscle actin (α-SMA) positive cells in control and treated sclera. Histologically, there was no sign of apoptosis in the sclera, choroid, and retina; and no side effects were found in the peripheral cornea and optic nerve adjacent to the treatment area. CONCLUSION Genipin induced crosslinking of collagen can increase its biomechanical behavior by direct strengthening of the extracellular matrix in rabbit sclera, with no α-SMA expression seen in the myofibroblasts. As there is no evidence of cytotoxicity in the scleral, choroidal, and retinal cells, genipin is likely a promising agent to strengthen the weakened sclera to prevent myopic progression.
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Affiliation(s)
- Tai-Xiang Liu
- Guizhou Ophthalmic Hospital, Affiliated Hospital of Zunyi Medical College, Zunyi 563003, Guizhou Province, China
| | - Zheng Wang
- Zhongshan Ophthalmic Center of Sun Yat-sen University, the State Key Laboratory of Ophthalmology, Guangzhou 510060, Guangdong Province, China
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Clinical Investigation of the Posterior scleral contraction to Treat Macular Traction Maculopathy in Highly Myopic Eyes. Sci Rep 2017; 7:43256. [PMID: 28220890 PMCID: PMC5318876 DOI: 10.1038/srep43256] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 01/20/2017] [Indexed: 11/26/2022] Open
Abstract
Myopic traction maculopathy (MTM) can cause vision disabilities in highly myopic eyes. This retrospective case series investigated the clinical outcomes of posterior scleral contraction (PSC) using genipin-cross-linked sclera as the material to treat MTM in highly myopic eyes. In total, 32 eyes from 29 highly myopic patients who underwent PSC for MTM were recruited. The changes in best-corrected visual acuity (BCVA) and axial length were evaluated, macular reattachment and macular hole (MH) closure was assessed by optical coherence tomography, and complications were evaluated. At the final follow-up, the retina was completely reattached in 25 eyes (78.1%), essentially reattached in 4 eyes (12.5%), and partially reattached in 3 eyes (9.4%). The logMAR BCVA improved significantly from 1.18 ± 0.45 preoperatively to 0.87 ± 0.45 postoperatively (P < 0.001). The 32 eyes were further divided into the MH group (16 eyes) and the non-MH group (16 eyes) for comparison. The MH was closed in 9 eyes (56.3%). The retinal reattachment rate was 75.0% in the MH group and 81.25% in the non-MH group, and the logMAR BCVA improved significantly in both groups. The PSC using genipin-cross-linked sclera as the material can effectively treat MTM in highly myopic eyes, and significant visual improvement can be achieved with minimal complications.
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Delgado LM, Fuller K, Zeugolis DI. * Collagen Cross-Linking: Biophysical, Biochemical, and Biological Response Analysis. Tissue Eng Part A 2017; 23:1064-1077. [PMID: 28071973 DOI: 10.1089/ten.tea.2016.0415] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Extracted forms of collagen are subjected to chemical cross-linking to enhance their stability. However, traditional cross-linking approaches are associated with toxicity and inflammation. This work investigates the stabilization capacity, cytotoxicity and inflammatory response of collagen scaffolds cross-linked with glutaraldehyde (GTA), 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, 4-arm polyethylene glycol (PEG) succinimidyl glutarate (4SP), genipin (GEN), and oleuropein. Although all cross-linking methods reduced free amine groups, variable data were obtained with respect to denaturation temperature, resistance to collagenase digestion, and mechanical properties. With respect to biological analysis, fibroblast cultures showed no significant difference between the treatments. Although direct cultures with human-derived leukemic monocyte cells (THP-1) clearly demonstrated the cytotoxic effect of GTA, THP-1 cultures supplemented with conditioned medium from the various groups showed no significant difference between the treatments. With respect to cytokine profile, no significant difference in secretion of proinflammatory (e.g., interleukin [IL]-1β, IL-8, tumor necrosis factor-α) and anti-inflammatory (e.g., vascular endothelial growth factor) cytokines was observed between the noncross-linked and the 4SP and GEN cross-linked groups, suggesting the suitability of these agents as collagen cross-linkers.
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Affiliation(s)
- Luis M Delgado
- 1 Regenerative, Modular & Developmental Engineering Laboratory (REMODEL), Biomedical Sciences Building, National University of Ireland Galway (NUI Galway) , Galway, Ireland .,2 Science Foundation Ireland (SFI), Centre for Research in Medical Devices (CÚRAM), Biomedical Sciences Building, National University of Ireland Galway (NUI Galway) , Galway, Ireland
| | - Kieran Fuller
- 1 Regenerative, Modular & Developmental Engineering Laboratory (REMODEL), Biomedical Sciences Building, National University of Ireland Galway (NUI Galway) , Galway, Ireland .,2 Science Foundation Ireland (SFI), Centre for Research in Medical Devices (CÚRAM), Biomedical Sciences Building, National University of Ireland Galway (NUI Galway) , Galway, Ireland
| | - Dimitrios I Zeugolis
- 1 Regenerative, Modular & Developmental Engineering Laboratory (REMODEL), Biomedical Sciences Building, National University of Ireland Galway (NUI Galway) , Galway, Ireland .,2 Science Foundation Ireland (SFI), Centre for Research in Medical Devices (CÚRAM), Biomedical Sciences Building, National University of Ireland Galway (NUI Galway) , Galway, Ireland
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25
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Lee J, Sabatini C. Glutaraldehyde collagen cross-linking stabilizes resin-dentin interfaces and reduces bond degradation. Eur J Oral Sci 2016; 125:63-71. [DOI: 10.1111/eos.12317] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/10/2016] [Indexed: 01/01/2023]
Affiliation(s)
- Joshua Lee
- Department of Restorative Dentistry; School of Dental Medicine; University at Buffalo; Buffalo NY USA
| | - Camila Sabatini
- Department of Restorative Dentistry; School of Dental Medicine; University at Buffalo; Buffalo NY USA
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Corneal elasticity after oxygen enriched high intensity corneal cross linking assessed using atomic force microscopy. Exp Eye Res 2016; 153:51-55. [PMID: 27725199 DOI: 10.1016/j.exer.2016.10.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 09/30/2016] [Accepted: 10/06/2016] [Indexed: 11/23/2022]
Abstract
The purpose of this study was to assess anterior and mid corneal stromal elasticity after high intensity (HI) corneal cross linking (CXL), with and without oxygen (O2) enrichment, and compare these results to conventional CXL. Experiments were performed on 25 pairs of human cadaver eyes, divided into four different groups. Group 1 included corneas that did not receive treatment and served as controls; Group 2 included corneas that received conventional CXL treatment (Dresden Protocol: corneal epithelial debridement, 30 min of riboflavin pretreatment followed by 30 min of exposure to 3 mW/cm2 of ultraviolet light); Group 3 included corneas that received HI CXL treatment (corneal epithelial debridement, 30 min of riboflavin pretreatment followed by 3 min of exposure to 30mW/cm2 of ultraviolet light); and Group 4 included corneas that received the same treatment as Group 3, except that they were enriched with oxygen (4 L per minute pure O2 gas stream) during ultraviolet irradiation. In each group, corneas were subdivided to assess anterior stromal elasticity and mid stromal elasticity. Corneal stromal elasticity was quantified using Atomic Force Microscopy (AFM) through micro-indentation. Young's modulus for the anterior corneal stroma was 14.5 ± 6.0 kPa, 80.7 ± 44.6 kPa, 36.6 ± 10.5 kPa, and 30.6 ± 9.2 kPa, for groups 1, 2, 3 and 4 respectively. Young's modulus for the mid corneal stroma was 5.8 ± 2.0 kPa, 20.7 ± 4.3 kPa, 12.1 ± 4.9 kPa, and 11.7 ± 3.7 kPa, for groups 1, 2, 3 and 4, respectively. In the anterior stromal region, conventional CXL demonstrated a significantly different result from the control, whereas the two HI CXL protocols were not significantly different from the control. There were no statistical differences between the two HI CXL protocols, although only the HI CXL protocol with O2 enrichment was significantly different from the conventional CXL group. In the mid stromal region, once again only conventional CXL demonstrated a significantly different result from the control. There were no statistical differences between the two HI CXL protocols, and both HI CXL protocols were significantly different from the conventional CXL group. Oxygen enriched HI CXL seems to offer similar changes in corneal elasticity when compared to HI CXL without the presence O2. Conventional CXL increases corneal stiffness more than HI CXL both with and without O2 enrichment.
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Bersanetti PA, Bueno TLN, Morandim-Giannetti ADA, Nogueira RF, Matos JR, Schor P. Characterization of Rabbit Corneas Subjected to Stromal Stiffening by the Açaí Extract (Euterpe oleracea). Curr Eye Res 2016; 42:528-533. [DOI: 10.1080/02713683.2016.1214970] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Patrícia A. Bersanetti
- Departamento de Informática em Saúde, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Tatiane L. N. Bueno
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | | | - Regina F. Nogueira
- Departamento de Informática em Saúde, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Jivaldo R. Matos
- Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Brazil
| | - Paulo Schor
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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Avila MY, Narvaez M, Castañeda JP. Effects of genipin corneal crosslinking in rabbit corneas. J Cataract Refract Surg 2016; 42:1073-7. [DOI: 10.1016/j.jcrs.2016.04.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 04/05/2016] [Accepted: 04/07/2016] [Indexed: 11/26/2022]
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Ohno-Matsui K, Lai TY, Lai CC, Cheung CMG. Updates of pathologic myopia. Prog Retin Eye Res 2016; 52:156-87. [DOI: 10.1016/j.preteyeres.2015.12.001] [Citation(s) in RCA: 260] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 12/28/2015] [Accepted: 12/30/2015] [Indexed: 12/20/2022]
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30
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Zhu SQ, Zheng LY, Pan AP, Yu AY, Wang QM, Xue AQ. The efficacy and safety of posterior scleral reinforcement using genipin cross-linked sclera for macular detachment and retinoschisis in highly myopic eyes. Br J Ophthalmol 2016; 100:1470-1475. [PMID: 26917677 DOI: 10.1136/bjophthalmol-2015-308087] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 01/14/2016] [Accepted: 01/19/2016] [Indexed: 11/03/2022]
Abstract
BACKGROUND/AIMS To evaluate the efficacy and safety of posterior scleral reinforcement (PSR) using genipin cross-linked sclera as the material to treat macular detachment and retinoschisis, both without macular hole, in highly myopic eyes. METHODS Twenty-one patients with highly myopic eyes (24 eyes) with macular detachment and retinoschisis were treated sequentially with genipin cross-linked PSR and were followed for at least 1 year after surgery. The best-corrected visual acuity (BCVA), spherical equivalent (SE) power, axial length (AL), optical coherence tomography, and the complications were evaluated. RESULTS The mean SE decreased from -13.81±4.67 D preoperatively to -9.64±4.86 D postoperatively, while the improvement in the logMAR BCVA values was from 1.24±0.57 before surgery to 1.03±0.57 after surgery. The preoperative AL (29.73±2.31 mm) was decreased (28.08±2.08 mm) after the operation. The retina in 21 eyes (87.5%) was successful reattached and the macular detachment was significantly decreased in two eyes; a macular hole occurred in one eye. CONCLUSIONS For at least a 1 year period of follow-up, PSR with genipin cross-linked sclera was safe and effective to treat macular detachment and retinoschisis in high myopia when a macular hole was not present. The reinforcement effect tended to be stabilised and maintained for 6 months after treatment.
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Affiliation(s)
- Shuang-Qian Zhu
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
| | - Lin-Yan Zheng
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
| | - An-Peng Pan
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
| | - A-Yong Yu
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
| | - Qin-Mei Wang
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
| | - An-Quan Xue
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
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Mechanisms of degradation of the hybrid layer in adhesive dentistry and therapeutic agents to improve bond durability—A literature review. Dent Mater 2016; 32:e41-53. [DOI: 10.1016/j.dental.2015.11.007] [Citation(s) in RCA: 193] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 10/19/2015] [Accepted: 11/30/2015] [Indexed: 12/25/2022]
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Keratoconus and Other Corneal Diseases: Pharmacologic Cross-Linking and Future Therapy. Handb Exp Pharmacol 2016; 242:137-161. [PMID: 27815790 DOI: 10.1007/164_2016_23] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The ability to cross-link collagen fibers and use this technique to strengthen the cornea has become of great interest to ophthalmologists in the last decade. For progressive diseases such as keratoconus, collagen cross-linking confers the possibility of halting progression and stabilizing the cornea, a benefit that is not observed with any other current treatment. Collagen cross-linking uses riboflavin combined with ultraviolet A light to induce the formation of bonds between collagen fibrils that strengthen the cornea. This chapter will discuss the theory, technique, indications, and complications of corneal cross-linking. Much of what will be discussed is in areas of active research that will likely be further clarified as more experience is gained with this procedure.
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Wang M, Corpuz CCC. Effects of scleral cross-linking using genipin on the process of form-deprivation myopia in the guinea pig: a randomized controlled experimental study. BMC Ophthalmol 2015. [PMID: 26220299 PMCID: PMC4518847 DOI: 10.1186/s12886-015-0086-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Background Scleral cross-linking (CXL) is a novel attempt to slow down the axial elongation process in animal eyes. As a natural CXL reagent, genipin would be also effective for the prevention of myopia process. Thus, the present study was designed to evaluate the effects of scleral cross-linking using genipin on the form-deprivation (FD) myopia process of guinea pigs. Methods Twenty-seven 3-week-old pigmented guinea pigs were randomly divided into three groups. Group A (n = 8) is the untreated control group. Group B (n = 8) is the FD control group, where all eyes were induced with monocular FD for 21 days. In Group C (n = 11), a sub-Tenon injection of 0.10 mL 0.50 % genipin was performed on FD eyes at day 0, 7 and 14 during the 21-day monocular FD. The ocular refraction, axial length, biomechanical test and light and electron microscopy were measured on all eyes to check the efficacy and safety of this scleral CXL technique. Results Compared with Group A, significant increases in myopic refractive errors, axial elongation and reductions of scleral fibril diameter and density were observed in the 21-day FD eyes of Group B (P < 0.05). In Group C, the scleral CXL resulted in less myopia and axial elongation as compared with Group B (P < 0.05); a significant thickening of scleral fibrils was found after sub-Tenon injections of genipin; no histological damage on the retina or choroid was observed in Group C at the end of this study. Conclusions The FD myopia in guinea pig eyes was effectively blocked by the scleral CXL using sub-Tenon injections of genipin. No histological damage was found on the retina or choroid of these treated eyes. Further studies are needed to examine the long-term efficacy and safety of this CXL technique. Electronic supplementary material The online version of this article (doi:10.1186/s12886-015-0086-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Mengmeng Wang
- Hebei Provincial Eye Hospital, Hebei Provincial Ophthalmology Key Lab, No.399 Quanbeidong Street, Xingtai City, Hebei Province, 054001, China.
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Dias J, Diakonis VF, Lorenzo M, Gonzalez F, Porras K, Douglas S, Avila M, Yoo SH, Ziebarth NM. Corneal stromal elasticity and viscoelasticity assessed by atomic force microscopy after different cross linking protocols. Exp Eye Res 2015; 138:1-5. [PMID: 26093276 DOI: 10.1016/j.exer.2015.06.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 06/04/2015] [Accepted: 06/16/2015] [Indexed: 11/29/2022]
Abstract
The purpose of this study was to evaluate elasticity and viscoelasticity in the anterior and deeper stromal regions of the cornea after cross linking with three different protocols using atomic force microscopy (AFM) through indentation. A total of 40 porcine corneas were used in this study and were divided into 4 groups (10 corneas per group): control (no treatment), Dresden (corneal epithelial debridement, riboflavin pretreatment for 30 min and a 3mw/cm(2) for 30 min UVA irradiation), accelerated (corneal epithelial debridement, riboflavin pretreatment for 30 min and a 30mw/cm(2) for 3 min UVA irradiation), and genipin (corneal epithelial debridement and submersion of anterior surface in a 1% genipin solution for 4 h). Elasticity and viscoelasticity were quantified using AFM through indentation for all corneas, for the anterior stroma and at a depth of 200 μm. For the control, Dresden, accelerated, and genipin groups, respectively, the average Young's modulus for the anterior stromal region was 0.60 ± 0.58 MPa, 1.58 ± 1.04 MPa, 0.86 ± 0.46 MPa, and 1.71 ± 0.51 MPa; the average for the 200 μm stromal depth was 0.08 ± 0.06 MPa, 0.08 ± 0.04 MPa, 0.08 ± 0.04 MPa, and 0.06 ± 0.01 MPa. Corneas crosslinked with the Dresden protocol and genipin were significantly stiffer than controls (p < 0.05) in the anterior region only. For the control, Dresden, Accelerated, and genipin groups, respectively, the average calculated apparent viscosity for the anterior stroma was 88.2 ± 43.7 kPa-s, 8.3 ± 7.1 kPa-s, 8.1 ± 2.3 kPa-s, and 9.5 ± 3.8 kPa-s; the average for the 200 μm stromal depth was 35.0 ± 3.7 kPa-s, 49.6 ± 35.1 kPa-s, 42.4 ± 17.6 kPa-s, and 41.8 ± 37.6 kPa-s. All crosslinking protocols resulted in a decrease in viscosity in the anterior region only (p < 0.05). The effects of cross-linking seem to be limited to the anterior corneal stroma and do not extend to the deeper stromal region. Additionally, the Dresden and genipin protocols seem to produce a stiffer anterior corneal stroma when compared to the accelerated protocol.
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Affiliation(s)
- Janice Dias
- Biomedical Atomic Force Microscopy Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, Miami, FL, USA
| | | | - Michael Lorenzo
- Biomedical Atomic Force Microscopy Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, Miami, FL, USA
| | - Felipe Gonzalez
- Biomedical Atomic Force Microscopy Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, Miami, FL, USA
| | - Kevin Porras
- Biomedical Atomic Force Microscopy Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, Miami, FL, USA
| | - Simone Douglas
- Biomedical Atomic Force Microscopy Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, Miami, FL, USA
| | - Marcel Avila
- Department of Ophthalmology, School of Medicine, Universidad Nacional de Colombia, Bogota, Colombia
| | - Sonia H Yoo
- Bascom Palmer Eye Institute, Miller School of Medicine, Miami, FL, USA
| | - Noël M Ziebarth
- Biomedical Atomic Force Microscopy Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, Miami, FL, USA.
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Natarajan V, Madhan B, Tiku ML. Intra-Articular Injections of Polyphenols Protect Articular Cartilage from Inflammation-Induced Degradation: Suggesting a Potential Role in Cartilage Therapeutics. PLoS One 2015; 10:e0127165. [PMID: 26046639 PMCID: PMC4457493 DOI: 10.1371/journal.pone.0127165] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 04/12/2015] [Indexed: 01/21/2023] Open
Abstract
Arthritic diseases, such as osteoarthritis and rheumatoid arthritis, inflict an enormous health care burden on society. Osteoarthritis, a degenerative joint disease with high prevalence among older people, and rheumatoid arthritis, an autoimmune inflammatory disease, both lead to irreversible structural and functional damage to articular cartilage. The aim of this study was to investigate the effect of polyphenols such as catechin, quercetin, epigallocatechin gallate, and tannic acid, on crosslinking type II collagen and the roles of these agents in managing in vivo articular cartilage degradation. The thermal, enzymatic, and physical stability of bovine articular cartilage explants following polyphenolic treatment were assessed for efficiency. Epigallocatechin gallate and tannic acid-treated explants showed >12 °C increase over native cartilage in thermal stability, thereby confirming cartilage crosslinking. Polyphenol-treated cartilage also showed a significant reduction in the percentage of collagen degradation and the release of glycosaminoglycans against collagenase digestion, indicating the increase physical integrity and resistance of polyphenol crosslinked cartilage to enzymatic digestion. To examine the in vivo cartilage protective effects, polyphenols were injected intra-articularly before (prophylactic) and after (therapeutic) the induction of collagen-induced arthritis in rats. The hind paw volume and histomorphological scoring was done for cartilage damage. The intra-articular injection of epigallocatechin gallate and tannic acid did not significantly influence the time of onset or the intensity of joint inflammation. However, histomorphological scoring of the articular cartilage showed a significant reduction in cartilage degradation in prophylactic- and therapeutic-groups, indicating that intra-articular injections of polyphenols bind to articular cartilage and making it resistant to degradation despite ongoing inflammation. These studies establish the value of intra-articular injections of polyphenol in stabilization of cartilage collagen against degradation and indicate the unique beneficial role of injectable polyphenols in protecting the cartilage in arthritic conditions.
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Affiliation(s)
- Venkatachalam Natarajan
- Council of Scientific and Industrial Research—Central Leather Research Institute, Adyar, Chennai, Tamil Nadu, India
| | - Balaraman Madhan
- Council of Scientific and Industrial Research—Central Leather Research Institute, Adyar, Chennai, Tamil Nadu, India
- * E-mail:
| | - Moti L. Tiku
- Rutgers, Robert Wood Johnson Medical School, New Brunswick, New Jersey, United States of America
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Babar N, Kim M, Cao K, Shimizu Y, Kim SY, Takaoka A, Trokel SL, Paik DC. Cosmetic preservatives as therapeutic corneal and scleral tissue cross-linking agents. Invest Ophthalmol Vis Sci 2015; 56:1274-82. [PMID: 25634979 DOI: 10.1167/iovs.14-16035] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
PURPOSE Previously, aliphatic β-nitroalcohols (BNAs) have been studied as a means to chemically induce tissue cross-linking (TXL) of cornea and sclera. There are a number of related and possibly more potent agents, known as formaldehyde releasers (FARs), that are in commercial use as preservatives in cosmetics and other personal care products. The present study was undertaken in order to screen such compounds for potential clinical utility as therapeutic TXL agents. METHODS A chemical registry of 62 FARs was created from a literature review and included characteristics relevant to TXL such as molecular weight, carcinogenicity/mutagenicity, toxicity, hydrophobicity, and commercial availability. From this registry, five compounds [diazolidinyl urea (DAU), imidazolidinyl urea (IMU), sodium hydroxymethylglycinate (SMG), DMDM hydantoin (DMDM), 5-Ethyl-3,7-dioxa-1-azabicyclo [3.3.0] octane (OCT)] were selected for efficacy screening using two independent systems, an ex vivo rabbit corneal cross-linking simulation setup and incubation of cut scleral tissue pieces. Treatments were conducted at pH 7.4 or 8.5 for 30 minutes. Efficacy was evaluated using thermal denaturation temperature (Tm), and cell toxicity was studied using the trypan blue exclusion method. RESULTS Cross-linking effects in the five selected FARs were pH and concentration dependent. Overall, the Tm shifts were in agreement with both cornea and sclera. By comparison with BNAs previously reported upon, the FARs identified in this study were significantly more potent but with similar or better cytotoxicity. CONCLUSIONS The FARs, a class of compounds well known to the cosmetic industry, may have utility as therapeutic TXL agents. The compounds studied thus far show promise and will be further tested.
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Affiliation(s)
- Natasha Babar
- Department of Ophthalmology, Columbia University College of Physicians and Surgeons, New York, New York, United States
| | - MiJung Kim
- Department of Ophthalmology, Columbia University College of Physicians and Surgeons, New York, New York, United States
| | - Kerry Cao
- Department of Ophthalmology, Columbia University College of Physicians and Surgeons, New York, New York, United States
| | - Yukari Shimizu
- Department of Ophthalmology, Columbia University College of Physicians and Surgeons, New York, New York, United States
| | - Su-Young Kim
- Department of Ophthalmology, Columbia University College of Physicians and Surgeons, New York, New York, United States
| | - Anna Takaoka
- Department of Ophthalmology, Columbia University College of Physicians and Surgeons, New York, New York, United States
| | - Stephen L Trokel
- Department of Ophthalmology, Columbia University College of Physicians and Surgeons, New York, New York, United States
| | - David C Paik
- Department of Ophthalmology, Columbia University College of Physicians and Surgeons, New York, New York, United States
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Sabatini C, Wu Z. Effect of Desensitizing Agents on the Bond Strength of Mild and Strong Self-etching Adhesives. Oper Dent 2015; 40:548-57. [PMID: 25575197 DOI: 10.2341/14-190-l] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND Desensitizing agents are used, almost as routine practice, in many adhesive restorative procedures. There is still debate as to their effect in dentin bonding, particularly with self-etching adhesives. The present study aimed to evaluate the effect of different desensitizing agents on the bond strength of mild and strong self-etching adhesive systems to dentin. MATERIALS AND METHODS One hundred twenty recently extracted, noncarious human molars were used to obtain superficial dentin substrate for bonding. No desensitizer was used in the control groups. The experimental groups were pretreated with Gluma Desensitizer, MicroPrime B, and Dentin Desensitizer immediately prior to bonding with self-etching adhesives Optibond XTR, Xeno IV, and iBond. A bonding jig was used to fabricate composite cylinders, which were stored for either 24 hours or three months, after which the shear bond strength (SBS) was evaluated using a notched-edge testing device at a crosshead speed of 1 mm/min. Failure mode distribution was also evaluated at 24 hours and three months. A two-way analysis of variance, Tukey test, and Student t-test, with a significance level of p<0.05, were used for data analysis. RESULTS At 24 hours, there was no significant difference in SBS when the same adhesive was used with any of the experimental desensitizing agents compared with the control group without desensitizer. However, at three months, Dentin Desensitizer bonded with Optibond XTR demonstrated significantly lower SBS (p<0.001), while Gluma bonded with iBond showed significantly higher SBS values (p=0.034) relative to their corresponding control group. Only MicroPrime B bonded with Xeno IV and iBond with no desensitizer demonstrated a significant reduction in SBS after three months (p=0.034 and p=0.002, respectively). The most prevalent type of failure was adhesive. CONCLUSION Desensitizing agents can be used in combination with self-etching adhesives to control hypersensitivity without adversely affecting their bond strength to dentin.
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Li YH, Cheng CY, Wang NK, Tan HY, Tsai YJ, Hsiao CH, Ma DHK, Yeh LK. Characterization of the modified chitosan membrane cross-linked with genipin for the cultured corneal epithelial cells. Colloids Surf B Biointerfaces 2014; 126:237-44. [PMID: 25576808 DOI: 10.1016/j.colsurfb.2014.12.029] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 12/13/2014] [Accepted: 12/16/2014] [Indexed: 12/22/2022]
Abstract
OBJECTIVES To modify a chitosan membrane (CM) by cross-linking the chitosan with genipin, a naturally occurring cross-linker extracted from Gardenia jasminoides fructus, with the aim of developing a new cell culture support and to observe the phenotypes of cultured human corneal epithelial cells (HCECs) on genipin-cross-linked chitosan membrane (GCM). METHODS We tested the cross-linking characteristics and mechanical strength of the GCM. CMs modified by cross-linking with different concentrations of genipin were prepared to investigate the rate of membrane degradation. The biocompatibility of the GCMs was investigated by determining the viability of HCECs cultured on them in vitro. The morphology of the HCECs cultured on CM or GCM was analyzed by confocal microscopy and scanning electron microscopy (SEM). Immunocytochemical staining was conducted to determine the phenotypes of the cultured cells. RESULTS The fixation index of the GCM was 31 ± 3% after treatment of CM with 0.5mM genipin. A stress-strain test showed that the GCM could tolerate three times the mechanical force of noncross-linked CM. The biodegradation rate of GCM was much slower than for CM. A 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay showed that cell viability was not affected by cross-linking with 5.0mM genipin. SEM showed that the cultured HCECs adhered to and grew well on the surface of the GCM. Immunocytochemical staining showed keratin 3 (K3) and connexin 43 (Cx-43) immunoreactive HCECs on the GCM and their proliferative ability was not significantly affected by strong immunoreactivity of Ki-67 and p63 markers. CONCLUSIONS GCM has potential as a scaffold for corneal epithelium in ocular surface surgery and greater mechanical strength and slower degradation than unmodified CM.
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Affiliation(s)
- Ya-Han Li
- Department of Ophthalmology, Chang-Gung Memorial Hospital, Linkou, Taiwan
| | - Ching-Yi Cheng
- Department of Cosmetic Science, Graduate Institute of Health Industry Technology, Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Kwei-Shan, Tao-Yuan, Taiwan
| | - Nan-Kai Wang
- Department of Ophthalmology, Chang-Gung Memorial Hospital, Linkou, Taiwan; Chang-Gung University College of Medicine, Taiwan
| | - Hsin-Yuan Tan
- Department of Ophthalmology, Chang-Gung Memorial Hospital, Linkou, Taiwan; Chang-Gung University College of Medicine, Taiwan
| | - Yueh-Ju Tsai
- Department of Ophthalmology, Chang-Gung Memorial Hospital, Linkou, Taiwan; Chang-Gung University College of Medicine, Taiwan
| | - Ching-Hsi Hsiao
- Department of Ophthalmology, Chang-Gung Memorial Hospital, Linkou, Taiwan; Chang-Gung University College of Medicine, Taiwan
| | - David Hui-Kang Ma
- Department of Ophthalmology, Chang-Gung Memorial Hospital, Linkou, Taiwan; Chang-Gung University College of Medicine, Taiwan
| | - Lung-Kun Yeh
- Department of Ophthalmology, Chang-Gung Memorial Hospital, Linkou, Taiwan; Chang-Gung University College of Medicine, Taiwan.
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Theoretical basis, laboratory evidence, and clinical research of chemical surgery of the cornea: cross-linking. J Ophthalmol 2014; 2014:890823. [PMID: 25215226 PMCID: PMC4151584 DOI: 10.1155/2014/890823] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 07/24/2014] [Accepted: 07/25/2014] [Indexed: 11/18/2022] Open
Abstract
Corneal cross-linking (CXL) is increasingly performed in ophthalmology with high success rates for progressive keratoconus and other types of ectasia. Despite being an established procedure, some molecular and clinical aspects still require additional studies. This review presents a critical analysis of some established topics and others that are still controversial. In addition, this review examines new technologies and techniques (transepithelial and ultrafast CXL), uses of corneal CXL including natural products and biomolecules as CXL promoters, and evidence for in vitro and in vivo indirect effectiveness.
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Sabatini C, Scheffel DLS, Scheffel RH, Agee KA, Rouch K, Takahashi M, Breschi L, Mazzoni A, Tjäderhane L, Tay FR, Pashley DH. Inhibition of endogenous human dentin MMPs by Gluma. Dent Mater 2014; 30:752-8. [PMID: 24846803 DOI: 10.1016/j.dental.2014.04.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 02/07/2014] [Accepted: 04/22/2014] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The objective of this study was to determine if Gluma dentin desensitizer (5.0% glutaraldehyde and 35% HEMA in water) can inhibit the endogenous MMPs of dentin matrices in 60 s and to evaluate its effect on dentin matrix stiffness and dry mass weight. METHODS Dentin beams of 2 mm×1 mm×6 mm were obtained from extracted human third molars coronal dentin. To measure the influence of Gluma treatment time on total MMP activity of dentin, beams were dipped in 37% phosphoric acid (PA) for 15 s and rinsed in water. The acid-etched beams were then dipped in Gluma for 5, 15, 30 or 60 s, rinsed in water and incubated into SensoLyte generic MMP substrate (AnaSpec, Inc.) for 60 min. Controls were dipped in water for 60 s. Additional beams of 1 mm×1 mm×6 mm were completely demineralized in 37% PA for 18 h, rinsed and used to evaluate changes on the dry weight and modulus of elasticity (E) after 60 s of Gluma treatment followed by incubation in simulated body fluid buffer for 0, 1 or 4 weeks. E was measured by 3-pt flexure. RESULTS Gluma treatment inhibited total MMP activity of acid-etched dentin by 44, 50, 84, 86% after 5, 15, 30 or 60 s of exposure, respectively. All completely demineralized dentin beams lost stiffness after 1 and 4 weeks, with no significant differences between the control and Gluma-treated dentin. Gluma treatment for 60 s yielded significantly less dry mass loss than the control after 4 weeks. SIGNIFICANCE The use of Gluma may contribute to the preservation of adhesive interfaces by its cross-linking and inhibitory properties of endogenous dentin MMPs.
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Affiliation(s)
- Camila Sabatini
- Department of Restorative Dentistry, School of Dental Medicine, University at Buffalo, Buffalo, NY, USA.
| | - Débora L S Scheffel
- Department of Orthodontics and Pediatric Dentistry, Universidade Estadual Paulista - UNESP, Araraquara Dental School, Araraquara, São Paulo, Brazil
| | - Régis H Scheffel
- Department of Orthodontics and Pediatric Dentistry, Universidade Estadual Paulista - UNESP, Araraquara Dental School, Araraquara, São Paulo, Brazil
| | - Kelli A Agee
- Department of Oral Biology, College of Dental Medicine, Georgia Regents University, Augusta, GA, USA
| | - Katelyn Rouch
- Department of Oral Biology, College of Dental Medicine, Georgia Regents University, Augusta, GA, USA
| | - Masahiro Takahashi
- Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University, Tokyo, Japan
| | - Lorenzo Breschi
- Department of Biomedicine, University of Trieste, Trieste, Italy; IGM-CNR, Unit of Bologna c/o IOR, Bologna, Italy
| | | | - Leo Tjäderhane
- Institute of Dentistry, University of Oulu and Oulu University Hospital, Oulu, Finland
| | - Franklin R Tay
- Department of Endodontics, College of Dental Medicine, Georgia Regents University, Augusta, GA, USA
| | - David H Pashley
- Department of Oral Biology, College of Dental Medicine, Georgia Regents University, Augusta, GA, USA; Highly Cited Investigator of King Abdulazis University School of Dentistry, Jeddah, Saudi Arabia
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Fessel G, Cadby J, Wunderli S, van Weeren R, Snedeker JG. Dose- and time-dependent effects of genipin crosslinking on cell viability and tissue mechanics - toward clinical application for tendon repair. Acta Biomater 2014; 10:1897-906. [PMID: 24384123 DOI: 10.1016/j.actbio.2013.12.048] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 11/21/2013] [Accepted: 12/18/2013] [Indexed: 12/19/2022]
Abstract
The crosslinking agent genipin is increasingly invoked for the mechanical augmentation of collagen tissues and implants, and has previously been demonstrated to arrest mechanical damage accumulation in various tissues. This study established an in vitro dose-response baseline for the effects of genipin treatment on tendon cells and their matrix, with a view to in vivo application to the repair of partial tendon tears. Regression models based on a broad range of experimental data were used to delineate the range of concentrations that are likely to achieve functionally effective crosslinking, and predict the corresponding degree of cell loss and diminished metabolic activity that can be expected. On these data, it was concluded that rapid mechanical augmentation of tissue properties can only be achieved by accepting some degree of cytotoxicity, yet that post-treatment cell survival may be adequate to eventually repopulate and stabilize the tissue. On this basis, development of delivery strategies and subsequent in vivo study seems warranted.
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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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Muthukumar T, Prabu P, Ghosh K, Sastry TP. Fish scale collagen sponge incorporated with Macrotyloma uniflorum plant extract as a possible wound/burn dressing material. Colloids Surf B Biointerfaces 2014; 113:207-12. [DOI: 10.1016/j.colsurfb.2013.09.019] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 08/16/2013] [Accepted: 09/06/2013] [Indexed: 11/26/2022]
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Mazzoni A, Apolonio FM, Saboia VPA, Santi S, Angeloni V, Checchi V, Curci R, Di Lenarda R, Tay FR, Pashley DH, Breschi L. Carbodiimide inactivation of MMPs and effect on dentin bonding. J Dent Res 2013; 93:263-8. [PMID: 24334409 DOI: 10.1177/0022034513516465] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The use of protein cross-linking agents during bonding procedures has been recently proposed to improve bond durability. This study aimed to use zymography and in situ zymography techniques to evaluate the ability of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) cross-linker to inhibit matrix metalloproteinase (MMP) activity. The hypotheses tested were that: (1) bonding procedures increase dentin gelatinolytic activity and (2) EDC pre-treatment prevents this enzymatic activity. The zymographic assay was performed on protein extracts obtained from dentin powder treated with Optibond FL or Scotchbond 1XT with or without 0.3M EDC pre-treatment. For in situ zymography, adhesive/dentin interfaces were created with the same adhesives applied to acid-etched dentin slabs pre-treated or not with EDC conditioner. Zymograms revealed increased expression of dentin endogenous MMP-2 and -9 after adhesive application, while the use of EDC as a primer inactivated dentin gelatinases. Results of in situ zymograpy showed that hybrid layers of tested adhesives exhibited intense collagenolytic activity, while almost no fluorescence signal was detected when specimens were pre-treated with EDC. The correlative analysis used in this study demonstrated that EDC could contribute to inactivate endogenous dentin MMPs within the hybrid layer created by etch-and-rinse adhesives.
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Affiliation(s)
- A Mazzoni
- Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Trieste, Italy
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Reich MS, Kishore V, Iglesias R, Akkus O. Genipin as a sporicidal agent for the treatment of cortical bone allografts. J Biomater Appl 2013; 28:1336-42. [DOI: 10.1177/0885328213507799] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Introduction Microbial bioburden in bone allografts can be reduced by gamma radiation; however, the radiation compromises collagen and increases the risk of graft failure. Genipin is an agent that may reduce bioburden by chemical crosslinking without causing mechanical detriment or cytotoxicity. Methods To evaluate genipin’s ability to penetrate cortical bone while maintaining sporicidal activity, Bacillus subtilis spore strips were isolated between slices of bovine femoral cortical bone and immersed in genipin solutions for up to one week; spore viability was assessed with media-based assays. The mechanical effects of genipin treatment were assessed by performing three-point bending tests on genipin-treated cortical beams. Cytotoxicity studies were conducted by evaluating the adhesion and proliferation of murine MC3T3-E1 (P21) preosteoblasts on cortical bone slices which were treated with genipin and rinsed to different extents. Results Genipin successfully penetrated cortical bone slices and sterilized B. subtilis populations after 48 hours ( p > 0.05) and one week ( p < 0.05). Genipin-treated cortical beams demonstrated dose-dependent increases in yield strain ( p = 0.02) and resilience ( p < 0.01), whereas other mechanical properties were not affected by genipin treatment. Seeding cells onto inadequately rinsed genipin-treated bones proved cytotoxic. However, with adequate post-treatment rinsing of the residual genipin, cell adhesion and proliferation was comparable to phosphate-buffered saline-treated controls (no genipin). Conclusions Genipin solutions can sterilize bacterial spore populations entrapped within the continuum of bone tissue while preserving mechanical properties of bone and allowing cell adhesion and proliferation. Provided that antimicrobial effects seen with bacterial spores extend broadly to all microbial and viral species, genipin holds strong potential for bone allograft sterilization.
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Affiliation(s)
- Michael S Reich
- Department of Orthopaedic Surgery, Case Western Reserve University, Cleveland, OH, USA
| | - Vipuil Kishore
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH, USA
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Rodrigo Iglesias
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH, USA
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Ozan Akkus
- Department of Orthopaedic Surgery, Case Western Reserve University, Cleveland, OH, USA
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH, USA
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
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Abstract
PURPOSE To evaluate the effect of collagen cross-linking induced by genipin in porcine sclera. METHODS Porcine cadaver eyes were treated with genipin at concentrations (by w/v) of 0.01%, 0.03%, 0.1%, 0.3%, 1.0% for 15 and 30 min. Riboflavin/ultraviolet A(UVA)-treated and untreated samples were used as controls. After treatment, scleral strips of 4.0 × 10.0 mm were cut. Twenty-four hours later, the stress-strain parameters of the strips were measured using a biomaterial microtester. The stress and Young's modulus at 8% strain were evaluated. RESULTS Compared with untreated groups, after treatment with genipin for 15 min, the stress was increased by 66-246%, depending on the concentration of genipin. As for the 30-min groups, the stress was 171-444% higher than that of the control. The difference of the Young's modulus between genipin 15-min groups, except the 0.01% groups (p = 0.095), also had statistical significance (p < 0.05). The Young's modulus had significant difference between the untreated group and the genipin 30-min groups (all p < 0.05). Of 0.3% genipin for 15 min or 0.01% genipin for 30 min had a similar stress-strain curve with those of eyes treated with the riboflavin/UVA group. The sclera exhibited a bluish colour which became deeper with increase concentration and cross-linking time. CONCLUSIONS Collagen cross-linking induced by genipin could increase the biomechanical strength in porcine sclera. The effect depends on the concentration and treatment time of genipin.
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Affiliation(s)
- Tai-Xiang Liu
- Zhongshan Ophthalmic Center at Sun Yat-sen University, The State Key Laboratory of Ophthalmology, Guangzhou, China
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Raiskup F, Spoerl E. Corneal crosslinking with riboflavin and ultraviolet A. I. Principles. Ocul Surf 2013; 11:65-74. [PMID: 23583042 DOI: 10.1016/j.jtos.2013.01.002] [Citation(s) in RCA: 175] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/01/2012] [Indexed: 01/20/2023]
Abstract
Changes in the biomechanical properties of the human cornea play an important role in the pathogenesis of corneal ectatic diseases. Biomechanical investigation shows significant differences between human ectatic corneas and normal corneas, including decreased stiffness and reduction of collagen crosslinks in the ectatic cornea. Induction of crosslinks is a well-established procedure in polymer chemistry to increase the elastic modulus of materials. Crosslinking (CXL) in connective tissue can occur during aging and as a side effect of diabetes mellitus. CXL has been used medically to increase stability and reduce the biodegradation of collagen-based biomaterials for bioprostheses. CXL of the cornea using riboflavin and UVA light with a wavelength of 370 nm and a dosage of 5.4 J/cm² is a new approach that increases the mechanical and biochemical stability of stromal tissue. This technique combines the principles of CXL (chemical and nonenzymatic) and the biochemical mechanisms of photo-oxidative CXL with riboflavin as a photosensitizer. In this review, the enrichment of riboflavin in the stroma by standard (epi-off) and transepithelial (epi-on) CXL is discussed. The theoretical and experimental measurements of the absorption of UV light explain the stronger CXL effect in the anterior stroma and its importance for the prevention of damage to the endothelial cells. UV devices are described. Changes of the physical properties after CXL, as well as the cellular changes, are discussed. From these basic investigations, treatment parameters for effective and safe CXL are identified.
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Affiliation(s)
- Frederik Raiskup
- Department of Ophthalmology, Carl Gustav Carus University Hospital, Dresden, Germany.
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Lai JY. Biocompatibility of genipin and glutaraldehyde cross-linked chitosan materials in the anterior chamber of the eye. Int J Mol Sci 2012; 13:10970-10985. [PMID: 23109832 PMCID: PMC3472724 DOI: 10.3390/ijms130910970] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 08/02/2012] [Accepted: 08/27/2012] [Indexed: 11/23/2022] Open
Abstract
Chitosan is a naturally occurring cationic polysaccharide and has attracted much attention in the past decade as an important ophthalmic biomaterial. We recently demonstrated that the genipin (GP) cross-linked chitosan is compatible with human retinal pigment epithelial cells. The present work aims to further investigate the in vivo biocompatibility of GP-treated chitosan (GP-chi group) by adopting the anterior chamber of a rabbit eye model. The glutaraldehyde (GTA) cross-linked samples (GTA-chi group) were used for comparison. The 7-mm-diameter membrane implants made from either non-cross-linked chitosan or chemically modified materials with a cross-linking degree of around 80% were inserted in the ocular anterior chamber for 24 weeks and characterized by slit-lamp and specular microscopic examinations, intraocular pressure measurements, and corneal thickness measurements. The interleukin-6 expressions at mRNA level were also detected by quantitative real-time reverse transcription polymerase chain reaction. Results of clinical observations showed that the overall ocular scores in the GTA-chi groups were relatively high. In contrast, the rabbits bearing GP-chi implants in the anterior chamber of the eye exhibited no signs of ocular inflammation. As compared to the non-cross-linked counterparts, the GP-chi samples improved the preservation of corneal endothelial cell density and possessed better anti-inflammatory activities, indicating the benefit action of the GP cross-linker. In summary, the intracameral tissue response to the chemically modified chitosan materials strongly depends on the selection of cross-linking agents.
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Affiliation(s)
- Jui-Yang Lai
- Institute of Biochemical and Biomedical Engineering, Chang Gung University, Taoyuan 33302, Taiwan; E-Mail: ; Tel.: +886-3-211-8800 (ext. 3598); Fax: +886-3-211-8668
- Biomedical Engineering Research Center, Chang Gung University, Taoyuan 33302, Taiwan
- Molecular Medicine Research Center, Chang Gung University, Taoyuan 33302, Taiwan
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Sporicidal efficacy of genipin: a potential theoretical alternative for biomaterial and tissue graft sterilization. Cell Tissue Bank 2012; 14:381-93. [PMID: 22875200 DOI: 10.1007/s10561-012-9335-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Accepted: 07/25/2012] [Indexed: 11/27/2022]
Abstract
Terminal sterilization of musculoskeletal allografts by gamma radiation minimizes the risk of disease transmission but impairs allograft mechanical properties. Commonly employed crosslinking agents can sterilize tissues without affecting mechanical properties adversely; however, these agents are toxic. Genipin is reported to be a benign crosslinking agent that strengthens mechanical properties of tissues; however, the antimicrobial capacity of genipin is largely unknown. The present study's aims were: (1) to assess the sporicidal potential of genipin, (2) to improve antimicrobial capacity by changing chemical and physical treatment conditions. To establish genipin's sterilization potential Bacillus subtilis var. niger spore strips were treated with 0-10% genipin in PBS or in 1:1 DMSO:PBS up to 72 h at room temperature (RT). Sterilizing doses and concentrations of genipin were used to treat B. pumilus and Geobacillus stearothermophilus spores to assess broader spectrum sporicidal activity of genipin. Scanning electron microscopy (SEM) was performed to evaluate gross morphological changes after genipin treatment. Optimal sterilization conditions were determined by evaluating the effects of temperature (RT-50 °C), DMSO:PBS ratio (0:100-100:0), and treatment duration (24-72 h) on B. subtilis. Genipin penetration of full thickness bovine patellar tendon and cortical bone specimens was observed to assess the feasibility of the agent for treating grafts. Initial studies showed that after 72 h of treatment at RT with 0.63-10% genipin/DMSO:PBS B. subtilis spore strips were sterilized; 0.63% genipin/PBS did not sterilize spore strips at 72 h at RT. Genipin doses and concentrations that sterilized B. subtilis spore strips sterilized B. pumilus and G. stearothermophilus spore strips. SEM revealed no gross morphological differences between untreated and treated spores. Treatment optimization resulted in sterilization within 24 h with 100% PBS, and DMSO facilitated sporicidal activity. Genipin penetrated full thickness patellar tendon specimens and 3.72 ± 0.58 mm in cortical bone specimens. Genipin sterilizes B. subtilis, B. pumilus, and G. stearothermophilus spore strips. It penetrates soft and hard tissues at doses previously shown to be non-toxic and to improve mechanical strength in collagen-rich soft tissues. Further studies are indicated to assess genipin's effects on the mechanical properties of genipin-sterilized grafts, the ability of genipin to eradicate infectious species other than spores, and to assess whether sterilant activity persists after penetrating tissues and biomaterials.
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