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Abstract
Human corneal transplantation to date suffers from the shortage of good-quality donor tissue, and in some conditions, allografting is contraindicated. A range of artificial replacements to donor allograft corneas have been developed. These range from keratoprostheses (KPro) that replace basic corneal functions of light transmission and protection to regenerative medicine strategies for regenerating one or more layers of the human cornea. This chapter reviews the advances made in developing artificial corneas or more accurately, artificial alternatives to donor allograft corneas for ocular application.
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Biomaterials-Enabled Regenerative Medicine in Corneal Applications. Regen Med 2013. [DOI: 10.1007/978-94-007-5690-8_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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53
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Wang XH, Li S, Liang L, Xu XD, Zhang XZ, Jiang FG. Evaluation of RGD peptide hydrogel in the posterior segment of the rabbit eye. JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 2012; 24:1185-97. [PMID: 23713422 DOI: 10.1080/09205063.2012.745714] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The aim of this study was to evaluate the biocompatibility and biodegradability of RGD peptide hydrogel in the posterior segment of the eye as a biomaterial potentially useful for sustained drug delivery systems. RGD peptide hydrogel was injected into the vitreous cavity and suprachoroidal space of rabbit eyes. Clinical follow-up and histological observation were performed up to four weeks. The biodegradability was also evaluated by the lifetime of the hydrogel which was defined by ophthalmoscopic observation or ultrasonography. The results showed that RGD peptide hydrogel was well tolerated in the vitreous cavity and suprachoroidal space, and disappeared from the injection sites progressively. As for suprachoroidal injection, the hydrogel was clearly identified by ultrasound echography and was confirmed innoxious to the retinal vessels by fluorescein angiography. Histological observations showed that the structures of retina, choroid and other tissues around the injection site remained normal after the injection. The lifetime of the hydrogel was 25.7 ± 2.65 days and 14.3 ± 3.3 days in the vitreous cavity and suprachoroidal space, respectively. The results obtained demonstrated that RGD peptide hydrogel, which showed excellent biocompatibility and favorable biodegradability in the posterior segment of rabbit eyes, appears to be a promising biomaterial to deliver drugs focally to the choroid and the retina.
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Affiliation(s)
- Xing-Hua Wang
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, PR China
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Yang T, Malkoch M, Hult A. Sequential interpenetrating poly(ethylene glycol) hydrogels prepared by UV-initiated thiol-ene coupling chemistry. ACTA ACUST UNITED AC 2012. [DOI: 10.1002/pola.26393] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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55
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Zhang Q, Fang Z, Cao Y, Du H, Wu H, Beuerman R, Chan-Park MB, Duan H, Xu R. High Refractive Index Inorganic-Organic Interpenetrating Polymer Network (IPN) Hydrogel Nanocomposite toward Artificial Cornea Implants. ACS Macro Lett 2012; 1:876-881. [PMID: 35607136 DOI: 10.1021/mz300078y] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The use of artificial cornea implants has received increasing attention for treating cornea-related diseases and vision errors due to the low side effects. To achieve long-term successful vision correction, stable and biocompatible materials of high refractive index (RI) need to be developed. Herein, we developed an interpenetrating polymer network (IPN) hydrogel containing well-dispersed ZnS nanoparticles (∼3 nm) covalently linked to the first polymer network, poly(2-hydroethyl methacrylate) (PHEMA). The second polymer network used was poly(acrylic acid) (PAA). The resultant ZnS/PHEMA/PAA IPN nanocomposite is clear and transparent at both dry and hydrated states with their RIs measured to be as high as 1.65 and 1.49, respectively. The equilibrium water content of the hydrogel nanocomposite reached 60.2% which is reasonably near to that of cornea. The material exerted minimal cytotoxicity toward primary epidermal keratinocyte cells. The high RI IPN hydrogel nanocomposite developed here might be an excellent candidate for artificial cornea implants.
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Affiliation(s)
- Quanyuan Zhang
- School of Chemical & Biomedical Engineering, Nanyang Technological University, N1.2, 62 Nanyang Drive, Singapore 637459
| | - Zheng Fang
- School of Chemical & Biomedical Engineering, Nanyang Technological University, N1.2, 62 Nanyang Drive, Singapore 637459
| | - Ye Cao
- School of Chemical & Biomedical Engineering, Nanyang Technological University, N1.2, 62 Nanyang Drive, Singapore 637459
| | - Huamao Du
- School of Chemical & Biomedical Engineering, Nanyang Technological University, N1.2, 62 Nanyang Drive, Singapore 637459
| | - Hong Wu
- Department of Ophthalmology, Second Hospital of Jilin University, Changchun, China
130041
| | - Roger Beuerman
- Singapore Eye Research Institute, 11 Third Hospital Ave 168751, Singapore 6223
8458
| | - Mary B. Chan-Park
- School of Chemical & Biomedical Engineering, Nanyang Technological University, N1.2, 62 Nanyang Drive, Singapore 637459
| | - Hongwei Duan
- School of Chemical & Biomedical Engineering, Nanyang Technological University, N1.2, 62 Nanyang Drive, Singapore 637459
| | - Rong Xu
- School of Chemical & Biomedical Engineering, Nanyang Technological University, N1.2, 62 Nanyang Drive, Singapore 637459
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Naeimi M, Karkhaneh A, Barzin J, Khorasani MT, Ghaffarieh A. Novel PDMS-based membranes: Sodium chloride and glucose permeability. J Appl Polym Sci 2012. [DOI: 10.1002/app.37709] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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57
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Griffith M, Polisetti N, Kuffova L, Gallar J, Forrester J, Vemuganti GK, Fuchsluger TA. Regenerative approaches as alternatives to donor allografting for restoration of corneal function. Ocul Surf 2012; 10:170-83. [PMID: 22814644 DOI: 10.1016/j.jtos.2012.04.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 04/22/2012] [Accepted: 04/01/2012] [Indexed: 12/13/2022]
Abstract
A range of alternatives to human donor tissue for corneal transplantation are being developed to address the shortfall of good quality tissues as well as the clinical conditions for which allografting is contraindicated. Classical keratoprostheses, commonly referred to as artificial corneas, are being used clinically to replace minimal corneal function. However, they are used only as last resorts, as they are associated with significant complications, such as extrusion/rejection, glaucoma, and retinal detachment. The past few years have seen significant developments in technologies designed to replace part or the full thickness of damaged or diseased corneas with materials that encourage regeneration to different extents. This review describes selected examples of these corneal substitutes, which range from cell-based regenerative strategies to keratoprostheses with regenerative capabilities via tissue-engineered scaffolds pre-seeded with stem cells. It is unlikely that one corneal substitute will be best for all indications, but taken together, the various approaches may soon be able to supplement the supply of human donor corneas for transplantation or allow restoration of diseased or damaged corneas that cannot be treated by currently available techniques.
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Affiliation(s)
- May Griffith
- Integrative Regenerative Medicine Centre, Department of Clinical and Experimental Medicine, Linköping University, Sweden.
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58
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Gendron R, Kumar MR, Paradis H, Martin D, Ho N, Gardiner D, Merschrod S. EF, Poduska KM. Controlled Cell Proliferation on an Electrochemically Engineered Collagen Scaffold. Macromol Biosci 2011; 12:360-6. [DOI: 10.1002/mabi.201100341] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 09/27/2011] [Indexed: 12/19/2022]
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Oelker AM, Grinstaff MW. Synthesis, characterization, and in vitro evaluation of a hydrogel-based corneal onlay. IEEE Trans Nanobioscience 2011; 11:37-45. [PMID: 21908258 DOI: 10.1109/tnb.2011.2166978] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Blindness due to opacity of the cornea is treated by corneal transplantation with donor tissue. Due to the limited supply of suitable donor corneas, the need for synthetic corneal equivalents is clear. Herein we report the design and in vitro characterization of a hydrogel-based implant; this implant will serve as a permanent, transparent, space-filling onlay with a two-layer design that mimics the native corneal stratification to support surface epithelialization and foster integration with the surrounding tissue. The top layer of the implant was composed of a 2-hydroxyethylmethacrylate hydrogel containing methacrylic acid as the co-monomer (HEMA-co-MAA) with tunable dimensions and compressive modulus ranging from 700-1000 kPa. The bottom layer, which constitutes the bulk of the implant and is designed to provide integration with the corneal stroma, is a dendrimer hydrogel with high water content and compressive modulus ranging from 500-1200 kPa. Both hydrogels were found to possess optical and diffusion properties similar to those of the human cornea. In addition, composite implants with uniform and structurally sound interfaces were formed when the gels were sequentially injected and cross-linked in the same mold. HEMA-co-MAA hydrogels were covalently modified with type I collagen to enable corneal epithelial cell adhesion and spreading that was dependent upon the collagen coating density but independent of hydrogel stiffness. Similarly, dendrimer hydrogels supported the adhesion and spreading of corneal fibroblasts upon modification with the adhesion ligand arginine-glycine-aspartic acid (RGD). Fibroblast adhesion was not dependent upon dendrimer hydrogel stiffness for the formulations studied and, after in vitro culture for 4 weeks, fibroblasts remained able to adhere to and conformally coat the hydrogel surface. In conclusion, the tunable physical properties and structural integrity of the laminated interface suggests that this design is suitable for further study. The judicious tuning of material properties and inclusion of bioactive moieties is a promising strategy for promotion of implant epithelialization and tissue integration.
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Fagerholm P, Lagali NS, Merrett K, Jackson WB, Munger R, Liu Y, Polarek JW, Söderqvist M, Griffith M. A biosynthetic alternative to human donor tissue for inducing corneal regeneration: 24-month follow-up of a phase 1 clinical study. Sci Transl Med 2010; 2:46ra61. [PMID: 20739681 DOI: 10.1126/scitranslmed.3001022] [Citation(s) in RCA: 246] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Corneas from human donors are used to replace damaged tissue and treat corneal blindness, but there is a severe worldwide shortage of donor corneas. We conducted a phase 1 clinical study in which biosynthetic mimics of corneal extracellular matrix were implanted to replace the pathologic anterior cornea of 10 patients who had significant vision loss, with the aim of facilitating endogenous tissue regeneration without the use of human donor tissue. The biosynthetic implants remained stably integrated and avascular for 24 months after surgery, without the need for long-term use of the steroid immunosuppression that is required for traditional allotransplantation. Corneal reepithelialization occurred in all patients, although a delay in epithelial closure as a result of the overlying retaining sutures led to early, localized implant thinning and fibrosis in some patients. The tear film was restored, and stromal cells were recruited into the implant in all patients. Nerve regeneration was also observed and touch sensitivity was restored, both to an equal or to a greater degree than is seen with human donor tissue. Vision at 24 months improved from preoperative values in six patients. With further optimization, biosynthetic corneal implants could offer a safe and effective alternative to the implantation of human tissue to help address the current donor cornea shortage.
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Affiliation(s)
- Per Fagerholm
- Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Cell Biology Building, Level 10, SE-581 83 Linköping, Sweden
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61
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Abstract
PURPOSE To assess integration of a biosynthetic corneal implant in dogs. METHODS Three normal adult laboratory Beagles underwent ophthalmic examinations, including slit-lamp biomicroscopy, indirect ophthalmoscopy, applanation tonometry, and Cochet-Bonnet aesthesiometry. Biosynthetic corneas fabricated from glutaraldehyde crosslinked collagen and copolymers of collagen and poly(N-isopropylacrylamide-co-acrylic acid-co-acryloxysuccinimide, denoted as TERP) were implanted into dogs by a modified epikeratoplasty technique. Ophthalmic examinations and aesthesiometry were performed daily for 5 days and then weekly thereafter for 16 weeks. Corneal samples underwent histopathological and transmission electron microscopy examination at 16 weeks. RESULTS Implants were epithelialized by 7 days. Intraocular pressure was within normal range throughout the study. Aesthesiometry values dropped from an average of 3.67 cm preoperatively to less than 1 mm for all dogs for the first postoperative weeks. By week 16, the average Cochet-Bonnet value was 1.67 cm, demonstrating partial recovery of functional innervation of the implant. No inflammation or rejection of the implant occurred, and minimal haze formation was noted. Light microscopy revealed thickened but normal epithelium over the implant with fibroblast migration into the scaffold. On transmission electron microscopy, the basement membrane was irregular but present and adhesion complexes were noted. CONCLUSION Biosynthetic corneal implantation is well tolerated in dogs, and the collagen-polymer hybrid construct holds promise for clinical application in animals and humans.
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Liu H, Zhang J, Liu CY, Wang IJ, Sieber M, Chang J, Jester JV, Kao WWY. Cell therapy of congenital corneal diseases with umbilical mesenchymal stem cells: lumican null mice. PLoS One 2010; 5:e10707. [PMID: 20502663 PMCID: PMC2873411 DOI: 10.1371/journal.pone.0010707] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2010] [Accepted: 04/19/2010] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Keratoplasty is the most effective treatment for corneal blindness, but suboptimal medical conditions and lack of qualified medical personnel and donated cornea often prevent the performance of corneal transplantation in developing countries. Our study aims to develop alternative treatment regimens for congenital corneal diseases of genetic mutation. METHODOLOGY/PRINCIPAL FINDINGS Human mesenchymal stem cells isolated from neonatal umbilical cords were transplanted to treat thin and cloudy corneas of lumican null mice. Transplantation of umbilical mesenchymal stem cells significantly improved corneal transparency and increased stromal thickness of lumican null mice, but human umbilical hematopoietic stem cells failed to do the same. Further studies revealed that collagen lamellae were re-organized in corneal stroma of lumican null mice after mesenchymal stem cell transplantation. Transplanted umbilical mesenchymal stem cells survived in the mouse corneal stroma for more than 3 months with little or no graft rejection. In addition, these cells assumed a keratocyte phenotype, e.g., dendritic morphology, quiescence, expression of keratocyte unique keratan sulfated keratocan and lumican, and CD34. Moreover, umbilical mesenchymal stem cell transplantation improved host keratocyte functions, which was verified by enhanced expression of keratocan and aldehyde dehydrogenase class 3A1 in lumican null mice. CONCLUSIONS/SIGNIFICANCE Umbilical mesenchymal stem cell transplantation is a promising treatment for congenital corneal diseases involving keratocyte dysfunction. Unlike donated corneas, umbilical mesenchymal stem cells are easily isolated, expanded, stored, and can be quickly recovered from liquid nitrogen when a patient is in urgent need.
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Affiliation(s)
- Hongshan Liu
- Department of Ophthalmology, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Jianhua Zhang
- Department of Ophthalmology, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Chia-Yang Liu
- Department of Ophthalmology, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - I-Jong Wang
- Department of Ophthalmology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | | | | | - James V. Jester
- Gavin Herbert Eye Institute, University of California Irvine Medical Center, Orange, California, United States of America
| | - Winston W. Y. Kao
- Department of Ophthalmology, University of Cincinnati, Cincinnati, Ohio, United States of America
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Sasaki S, Funamoto S, Hashimoto Y, Kimura T, Honda T, Hattori S, Kobayashi H, Kishida A, Mochizuki M. In vivo evaluation of a novel scaffold for artificial corneas prepared by using ultrahigh hydrostatic pressure to decellularize porcine corneas. Mol Vis 2009; 15:2022-8. [PMID: 19844587 PMCID: PMC2763123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2009] [Accepted: 10/05/2009] [Indexed: 11/27/2022] Open
Abstract
PURPOSE To evaluate the stability and biocompatibility of artificial corneal stroma that was prepared by using ultrahigh hydrostatic pressurization treatment to decellularize corneas. METHODS The porcine cornea was decellularized by two methods, a detergent method and an ultrahigh hydrostatic pressure (UHP) method. Either 1% w/v Triton X-100 or sodium dodecyl sulfate (SDS) was used for the detergent method, and 10,000 atmospheres (atm; 7.6x10(6) mmHg) was applied to the cornea for 10 min at 10 degrees C by a high-pressure machine for the UHP method. Hematoxylin-eosin staining was performed to confirm the removal of the corneal cells, and then decellularized porcine corneal stroma was implanted into rabbit corneal pockets. After eight weeks, the rabbit eyes were enucleated to examine the tissue compatibility of the implanted stroma. RESULTS Complete decellularization was confirmed only in corneas treated by the UHP method, and little inflammation was seen when they were implanted into the rabbit corneal pockets. CONCLUSIONS Porcine corneal stroma completely decellularized by the UHP method has extremely high biocompatibility and is a possible corneal scaffold for an artificial cornea.
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Affiliation(s)
- Shuji Sasaki
- Department of Ophthalmology, Tokyo Medical and Dental University, Tokyo, Japan,Department of Ophthalmology, Tokyo Metropolitan Hiroo Hospital, Tokyo, Japan,Biomaterials Center, National Institute for Materials Science, Tsukuba, Japan
| | - Seiichi Funamoto
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan,Biomaterials Center, National Institute for Materials Science, Tsukuba, Japan,JST-CREST, Saitama, Japan
| | - Yoshihide Hashimoto
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan,Biomaterials Center, National Institute for Materials Science, Tsukuba, Japan,Japan Society for the Promotion of Science, Tokyo, Japan
| | - Tsuyoshi Kimura
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan,Biomaterials Center, National Institute for Materials Science, Tsukuba, Japan
| | - Takako Honda
- Biomaterials Center, National Institute for Materials Science, Tsukuba, Japan,Japan Health Sciences Foundation, Tokyo, Japan
| | - Shinya Hattori
- Biomaterials Center, National Institute for Materials Science, Tsukuba, Japan,Japan Health Sciences Foundation, Tokyo, Japan
| | - Hisatoshi Kobayashi
- Biomaterials Center, National Institute for Materials Science, Tsukuba, Japan
| | - Akio Kishida
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan,Biomaterials Center, National Institute for Materials Science, Tsukuba, Japan,JST-CREST, Saitama, Japan
| | - Manabu Mochizuki
- Department of Ophthalmology, Tokyo Medical and Dental University, Tokyo, Japan
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Carretti E, Grassi S, Cossalter M, Natali I, Caminati G, Weiss RG, Baglioni P, Dei L. Poly(vinyl alcohol)-borate hydro/cosolvent gels: viscoelastic properties, solubilizing power, and application to art conservation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:8656-8662. [PMID: 20050046 DOI: 10.1021/la804306w] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We report the development of a new type of hydrogel in which a cosolvent has been added to the water component. The gel networks are based on the well-known poly(vinyl alcohol)-borate systems (PVA-borate). However, it is shown that the rheological and solubilizing properties of the hydrogels can be modified drastically by the addition of a cosolvent. The studies have focused on 1-propanol as the added liquid, although it is shown that others (propylene carbonate, 1-pentanol, cyclohexanone, and 2-butanol) are amenable to making modified hydrogels as well. In addition to the rheological measurements, the gels have been investigated by differential scanning calorimetry (free water index) and determination of their solubilizing power. Finally, the gels have been applied to clean and oxidized varnish (patina) from the surface of a XVI-XVII century oil-on-wood painting by Ludovico Cardi detto il Cigoli. The mode of cleaning by and removal of the PVA-borate water/1-propanol gel from the painted surface demonstrate several advantages over other gels used in art conservation.
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Affiliation(s)
- Emiliano Carretti
- Department of Chemistry & CSGI Consortium, University of Florence, via della Lastruccia, 3 I-50019 Sesto Fiorentino, Florence, Italy
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65
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Abstract
Corneal substitutes are being developed to address the shortage of human donor tissues as well as the current disadvantages in some clinical indications, which include immune rejection. In the past few years, there have been significant developments in bioengineered corneas that are designed to replace part or the full thickness of damaged or diseased corneas that range from keratoprostheses that solely address the replacement of the cornea's function, through tissue-engineered hydrogels that permit regeneration of host tissues. We describe examples of corneal substitutes that encourage regeneration of the host tissue. We also contend that it is unlikely that there will be a single "one-size-fits-all" corneal substitute for all indications. Instead, there will most likely be a small range of corneal substitutes ranging from prostheses to tissue-engineered matrix substitutes that are tailored to different clusters of clinical indications. The tissue-engineered matrices can either be produced as sterile acellular matrices, or complete with functional cells, ready for implantation.
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66
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Cyclops. Can J Ophthalmol 2008. [DOI: 10.3129/i08-109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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