| 1. |
- Ahn, Jae-Il, et al.
(författare)
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Crosslinked collagen hydrogels as corneal implants: Effects of sterically bulky vs. non-bulky carbodiimides as crosslinkers
- 2013
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Ingår i: Acta Biomaterialia. - : Elsevier. - 1742-7061 .- 1878-7568. ; 9:8, s. 7796-7805
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Tidskriftsartikel (refereegranskat)abstract
- We have previously shown that recombinant human collagen can be crosslinked with N-(3-dimethylaminopropyl)-N-ethylcarbodiimide (EDC) to fabricate transparent hydrogels possessing the shape and dimensions of the human cornea. These corneal implants have been tested in a Phase I human clinical study. Although these hydrogels successfully promoted corneal tissue and nerve regeneration, the gelling kinetics were difficult to control during the manufacture of the implants. An alternative carbodiimide capable of producing hydrogels of similar characteristics as EDC in terms of strength and biocompatibility, but with a longer gelation time would be a desirable alternative. Here, we compared the crosslinking kinetics and properties of hydrogels crosslinked with a sterically bulky carbodiimide, N-Cyclohexyl-N-(2-morpholinoethyl) carbodiimide metho-p-toluenesulfonate (CMC), with that of EDC. CMC crosslinking was possible at ambient temperature whereas the EDC reaction was too rapid to control and had to be carried out at low temperatures. The highest tensile strength obtained using optimized formulations were equivalent, although CMC crosslinked hydrogels were found to be stiffer. The collagenase resistance of CMC crosslinked hydrogels was superior to that of EDC crosslinked hydrogels while biocompatibility was similar. We are also able to substitute porcine collagen with recombinant human collagen and show that the in vivo performance of both resulting hydrogels as full-thickness corneal implants is comparable in a mouse model of an orthotopic corneal graft. In conclusion, CMC is a viable alternative to EDC as a crosslinker for collagen-based biomaterials for use as corneal implants, and potentially for use in other tissue engineering applications.
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| 2. |
- Griffith, May, et al.
(författare)
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Regenerative Approaches as Alternatives to Donor Allografting for Restoration of Corneal Function
- 2012
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Ingår i: The Ocular Surface. - : Elsevier. - 1542-0124. ; 10:3, s. 170-183
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Lee, Chyan-Jang, et al.
(författare)
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Cathelicidin LL-37 and HSV-1 Corneal Infection : Peptide Versus Gene Therapy
- 2014
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Ingår i: Translational Vision Science & Technology. - : Association for Research in Vision and Ophthalmology. - 2164-2591. ; 3:3, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To evaluate the potential utility of collagen-based corneal implants with anti?Herpes Simplex Virus (HSV)-1 activity achieved through sustained release of LL-37, from incorporated nanoparticles, as compared with cell-based delivery from model human corneal epithelial cells (HCECs) transfected to produce endogenous LL-37. Methods: We tested the ability of collagen-phosphorylcholine implants to tolerate the adverse microenvironment of herpetic murine corneas. Then, we investigated the efficacy of LL-37 peptides delivered through nanoparticles incorporated within the corneal implants to block HSV-1 viral activity. In addition, LL-37 complementary DNA (cDNA) was transferred into HCECs to confer viral resistance, and their response to HSV-1 infection was examined. Results: Our implants remained in herpetic murine corneas 7 days longer than allografts. LL-37 released from the implants blocked HSV-1 infection of HCECs by interfering with viral binding. However, in pre-infected HCECs, LL-37 delayed but could not prevent viral spreading nor clear viruses from the infected cells. HCECs transfected with the LL-37 expressed and secreted the peptide. Secreted LL-37 inhibited viral binding in vitro but was insufficient to protect cells completely from HSV-1 infection. Nevertheless, secreted LL-37 reduced both the incidence of plaque formation and plaque size. Conclusion: LL-37 released from composite nanoparticle-hydrogel corneal implants and HCEC-produced peptide, both showed anti?HSV-1 activity by blocking binding. However, while both slowed down virus spread, neither was able on its own to completely inhibit the viruses. Translational Relevance: LL-37 releasing hydrogels may have potential utility as corneal substitutes for grafting in HSV-1 infected corneas, possibly in combination with LL-37 producing therapeutic cells.
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