| 1. |
- Blais, David R., et al.
(författare)
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LBP and CD14 secreted in tears by the lacrimal glands modulate the LPS response of corneal epithelial cells
- 2005
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Ingår i: Investigative Ophthalmology and Visual Science. - : Association for Research in Vision and Ophthalmology (ARVO). - 0146-0404 .- 1552-5783. ; 46:11, s. 4235-4244
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE. Lipopolysaccharide (LPS) is one of the most powerful bacterial virulence factors in terms of proinflammatory properties and is likely to contribute to corneal bacterial keratitis. Better understanding of the spatial expression of the LPS receptor components at the tear - corneal interface might facilitate enhanced functions of the LPS receptor complex in ocular defense against Gram-negative infections. METHODS. The expression of LPS-binding protein (LBP), CD14, toll-like receptor (TLR)-4, and MD-2 in human lacrimal glands, reflex tears, and corneal epithelia was examined by ELISA, RT-PCR, Western blot analysis, and immunofluorescence. The release of proinflammatory cytokines after the activation of primary and immortalized corneal epithelial cells with LPS and human tears was measured by ELISA. RESULTS. LBP and CD14 proteins were detected in reflex human tears. Human lacrimal glands and corneal epithelia expressed LBP, CD14, TLR4, and MD-2 mRNAs and proteins. In the corneal epithelium, LBP was mainly expressed by superficial and basal epithelial cells, whereas CD14, TLR4, and MD-2 expression were limited to the wing and basal epithelial cells. In a dose-dependant manner, tear CD14 and LBP mediated the secretion of interleukin (IL)-6 and IL-8 by corneal epithelia cells when challenged with LPS. CONCLUSIONS. Tear CD14 and LBP complemented the LPS receptor complex expressed by the corneal epithelia to trigger an immune response in the presence of LPS. The complementation of these tear and corneal immune proteins could play an important role in LPS recognition and signaling and, therefore, could modulate ocular innate immunity.
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| 2. |
- Gian Vascotto, Sandy, et al.
(författare)
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Localization of candidate stem and progenitor cell markers within the human cornea, limbus, and bulbar conjunctiva in vivo and in cell culture
- 2006
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Ingår i: Anatomical Record Part A-discoveries in Molecular Cellular and Evolutionary Biology. - : John Wiley and Sons, Ltd. - 1552-4884 .- 1932-8494 .- 1552-4892. ; 288A:8, s. 921-931
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Tidskriftsartikel (refereegranskat)abstract
- Corneal diseases are some of the most prevalent causes of blindness worldwide. While the most common treatment for corneal blindness is the transplantation of cadaver corneas, expanded limbal stem cells are finding recent application. Unknown, however, is the identity of the actual repopulating stem cell fraction utilized in both treatments and the critical factors governing successful engraftment and repopulation. In order to localize potential stem cell populations in vivo, we have immunohistochemically mapped a battery of candidate stem and progenitor cell markers including c-Kit and other growth factor receptors, nuclear markers including Delta Np63, as well as adhesion factors across the cornea and distal sclera. Cell populations that differentially and specifically stained for some of these markers include the basal and superficial limbal/conjunctival epithelium and scattered cells within the substantia propria of the bulbar conjunctiva. We have also determined that the culture of differentiated cornea epithelial cells as dissociated and explant cultures induces the expression of several markers previously characterized as candidate limbal stem cell markers. This study provides a foundation to explore candidate corneal stem cell populations. As well, we show that expression of traditional stem cell markers may not be reliable indicator of stem cell content during limbal stem cell expansion in vitro and could contribute to the variable success rates of corneal stem cell transplantation.
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| 3. |
- Li, Fengfu, et al.
(författare)
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Cellular and nerve regeneration within a biosynthetic extracellular matrix for corneal transplantation
- 2003
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences; 1999. - 0027-8424 .- 1091-6490. ; 100:26, s. 15346-15351
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Tidskriftsartikel (refereegranskat)abstract
- Our objective was to determine whether key properties of extracellular matrix (ECM) macromolecules can be replicated within tissue-engineered biosynthetic matrices to influence cellular properties and behavior. To achieve this, hydrated collagen and N-isopropylacrylamide copolymer-based ECMs were fabricated and tested on a corneal model. The structural and immunological simplicity of the cornea and importance of its extensive innervation for optimal functioning makes it an ideal test model. In addition, corneal failure is a clinically significant problem. Matrices were therefore designed to have the optical clarity and the proper dimensions, curvature, and biomechanical properties for use as corneal tissue replacements in transplantation. In vitro studies demonstrated that grafting of the laminin adhesion pentapeptide motif, YIGSR, to the hydrogels promoted epithelial stratification and neurite in-growth. Implants into pigs corneas demonstrated successful in vivo regeneration of host corneal epithelium, stroma, and nerves. In particular, functional nerves were observed to rapidly regenerate in implants. By comparison, nerve regeneration in allograft controls was too slow to be observed during the experimental period, consistent with the behavior of human cornea transplants. Other corneal substitutes have been produced and tested, but here we report an implantable matrix that performs as a physiologically functional tissue substitute and not simply as a prosthetic device. These biosynthetic ECM replacements should have applicability to many areas of tissue engineering and regenerative medicine, especially where nerve function is required.
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| 4. |
- McLaughlin, Christopher, et al.
(författare)
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Regeneration of Corneal Cells and Nerves in an Implanted Collagen Corneal Substitute
- 2008
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Ingår i: Cornea. - 0277-3740 .- 1536-4798. ; 27:5, s. 580-589
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Our objective was to evaluate promotion of tissue regeneration by extracellular matrix (ECM) mimics, by using corneal implantation as a model system.METHODS: Carbodiimide cross-linked porcine type I collagen was molded into appropriate corneal dimensions to serve as substitutes for natural corneal ECM. These were implanted into corneas of mini-pigs after removal of the host tissue, and tracked over 12 months, by clinical examination, slit-lamp biomicroscopy, in vivo confocal microscopy, topography, and esthesiometry. Histopathology and tensile strength testing were performed at the end of 12 months. Other samples were biotin labeled and implanted into mice to evaluate matrix remodeling.RESULTS: The implants promoted regeneration of corneal cells, nerves, and the tear film while retaining optical clarity. Mechanical testing data were consistent with stable, seamless host-graft integration in regenerated corneas, which were as robust as the untreated fellow corneas. Biotin conjugation is an effective method for tracking the implant within the host tissue.CONCLUSIONS: We show that a simple ECM mimetic can promote regeneration of corneal cells and nerves. Gradual turnover of matrix material as part of the natural remodeling process allowed for stable integration with host tissue and restoration of mechanical properties of the organ. The simplicity in fabrication and shown functionality shows potential for ECM
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