| 1. |
- Bourghardt Peebo, Beatrice, 1968-, et al.
(författare)
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Expression of the focal adhesion protein PINCH in normal and alkali-injured corneas and the role of PMNs
- 2007
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Ingår i: Acta Ophthalmologica Scandinavica. - : Wiley. - 1395-3907 .- 1600-0420. ; 85:4, s. 395-400
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To evaluate the role of particularly interesting new cysteine-histidine-rich protein (PINCH) in corneal wound healing and early neovascularization and to assess the influence of granulocytes. Methods: A standardized corneal alkali wound was inflicted under general anaesthesia to the right eye of 14 New Zealand White rabbits. Seven of the rabbits received i.v. 5 mg/kg fucoidin every 2 hours to prevent granulocytes from entering the wound area. After 36 hours, the rabbits were killed, the corneas excised, fixed in 4% formaldehyde and embedded in paraffin. The sections were double-stained with antibodies against PINCH and with haematoxylin. Results: In the normal cornea and limbus, PINCH was weakly expressed in the corneal epithelium and in a wedge of the conjunctival stroma. In the wounded corneas, PINCH expression was seen in the frontline of repopulating endothelial and epithelial cells, and in active keratocytes. The vascular endothelium and the granulocytes expressed PINCH, as did the conjunctival epithelium. In the fucoidin-treated rabbits, PINCH expression was markedly reduced. The vascular endothelial cells and the few granulocytes did not express PINCH in these rabbits. Conclusions: PINCH is only slightly expressed in the normal cornea. A corneal wound induces PINCH expression in the repopulating cells, in the vascular endothelial cells of the limbus, in the limbal epithelium and in the granulocytes. Exclusion of granulocytes reduces expression of PINCH and there is no expression at all in the vascular endothelium. © 2007 The Authors Journal compilation 2007 Acta Ophthalmol Scand.
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| 2. |
- Fagerholm, Per, 1948-, et al.
(författare)
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Vascular endothelial growth factor (VEGF) and its receptor VEGFR-2 in the regulation of corneal neovascularization and wound healing
- 2004
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Ingår i: Acta Ophthalmologica Scandinavica. - : Wiley. - 1395-3907 .- 1600-0420. ; 82:5, s. 557-563
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To study the change in expression of vascular endothelial growth factor (VEGF) and its receptor VEGFR-2 in the rabbit cornea and limbus following a penetrating, central corneal alkali burn. The influence of different cells on VEGF and VEGFR-2 expression was studied by excluding granulocytes from the wound area. Methods: Fourteen New Zealand white rabbits were subjected to a penetrating, 5-mm diameter, central corneal alkali burn in one eye under general anaesthesia. Seven of the rabbits were given injections of fucoidin for 36 hours. The rabbits were killed after 36 hours and the corneas were excised with a sclera rim and prepared for immunohistochemistry. Results: Both VEGF and VEGFR-2 are strongly expressed in the frontline of repopulating epithetial, stromal and endothelial cells during wound healing, irrespective of granulocyte presence. Vascular endothelial cells express VEGF strongly after injury, but only in the presence of granulocytes. Conclusion: Corneal neovascularization requires the presence of granulocytes to stimulate vascular endothelial cells. During wound healing in this area, VEGF is a factor that stimulates proliferation and migration and that is not influenced by granulocytes.
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| 3. |
- Gan, Lisha, 1957-, et al.
(författare)
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Cellular proliferation and leukocyte infiltration in the rabbit cornea after photorefractive keratectomy
- 2001
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Ingår i: Acta Ophthalmologica Scandinavica. - : Wiley. - 1395-3907 .- 1600-0420. ; 79:5, s. 488-492
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To map the proliferative activity of corneal cells during wound healing following photorefractive keratectomy (PRK) and to compare two markers for proliferation. Methods: PRK, 5- mm in diameter with a -6 D setting, was performed in one eye of 28 New Zealand White Rabbits. The rabbits were sacrificed at time points between 12 hours and three months after surgery. The treated and fellow corneas were fixed in 10% formaldehyde, paraffin embedded, and immunohistochemically stained for proliferate cell nuclear antigen (PCNA) and at one time point, 1 week, also for Ki-67. Results: Following initial sliding of the epithelial cells, the proliferative activity in the wound area starts in the leading edge (24 hours) and is spread towards the periphery. The proliferative activity peaks after one week and subsides during the following two weeks. Early (24 hours) proliferative activity is also seen in the limbal epithelium which peaks after three days. The keratocytes express PCNA in the peripheral stroma 48 hours after injury. They then also migrate to repopulate the stroma under the wound area. The expression period lasts 1 week and subsides the following week. Leukocytes are found in the wound as early as 12 hours after injury. The cells disappear around the time of epithelial wound closure, i.e. after 3 days. The two proliferative markers PCNA and KI 67 show a similar distribution after surgery. Conclusion: Epithelial proliferative activity starts earlier after injury, and is preceded by leukocyte presence in the wound. The PCNA expression starts later in the keratocytes but lasts somewhat longer (3 weeks). PCNA expression appears more efficient than Ki-67 to show proliferative activity of slow cycling cells in the cornea.
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| 4. |
- Gan, Lisha, 1957-, et al.
(författare)
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Expression of basic fibroblast growth factor in rabbit corneal alkali wounds in the presence and absence of granulocytes
- 2005
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Ingår i: Acta Ophthalmologica Scandinavica. - : Wiley. - 1395-3907 .- 1600-0420. ; 83:3, s. 374-378
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To study the expression of basic fibroblast growth factor (bFGF) in the early phases of corneal wound healing in the presence or absence of granulocytes. Methods: A central penetrating corneal alkali wound was inflicted to one eye in each of 14 rabbits under general anaesthesia. Subsequently, seven of the rabbits were given fucoidin i.v. for 36 hours in order to block the selectins on the vascular endothelium, thus preventing blood granulocytes from entering the tissues. Then, corneas were prepared, stained for bFGF and evaluated by light microscopy. Results: Whereas normal corneal epithelium expressed bFGF weakly, conjunctival epithelium did so strongly, particularly the goblet cells. The corneal endothelium showed medium staining, while keratocytes and vascular endothelial cells did not consistently express bFGF. After 36 hours of wound healing, a marked upregulation of bFGF expression was observed in the corneal epithelial and endothelial cells, as well as in the keratocytes, that were migrating into the wound. No other changes were noted. None of these features were modulated when granulocyte emigration was prevented by fucoidin administration. Conclusions: The difference in bFGF expression between the corneal and conjunctival epithelium suggests a role for this growth factor in the barrier function at the limbus. Moreover, the specific presence of bFGF in cells migrating into the wound indicates the participation of bFGF in corneal wound healing. Expression of bFGF was independent of granulocytes. Copyright © Acta Ophthalmol Scand 2005.
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| 5. |
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| 6. |
- Liu, Yuwen, et al.
(författare)
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A simple, cross-linked collagen tissue substitute for corneal implantation
- 2006
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Ingår i: Investigative Ophthalmology and Visual Science. - : Association for Research in Vision and Ophthalmology (ARVO). - 0146-0404 .- 1552-5783. ; 47:5, s. 1869-1875
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE. To develop a simple corneal substitute from crosslinked collagen. METHODS. Porcine type I collagen (10%, pH 5), was mixed with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The final homogenous solution was molded to corneal dimensions, cured, and then implanted into rabbits and minipigs by lamellar keratoplasty. The implants were followed for up to 6 months after surgery. Clinical examinations of the cornea included detailed slit lamp biomicroscopy, in vivo confocal microscopy, topography and esthesiometry for nerve function. Histopathologic examinations were also performed on rabbit corneas harvested after 6 months. RESULTS. Cross-linked collagen (refractive index, 1.35) had optical clarity superior to human corneas. Implanted into rabbit and porcine corneas, only 1 of 24 of the surgical corneas showed a slight haze at 6 months after surgery. All other implants showed no adverse reactions and remained optically clear. Topography showed a smooth surface and a profile similar to that of the contralateral nonsurgical eye. The implanted matrices promoted regeneration of corneal cells, tear film, and nerves. Touch sensitivity was restored, indicating some restoration of function. The corneas with implants showed no significant loss of thickness and demonstrated stable host- graft integration. CONCLUSIONS. Collagen can be adequately stabilized, using water soluble carbodiimides as protein cross-linking reagents, in the fabrication of corneal matrix substitutes for implantation. The simple cross-linking methodology would allow for easy fabrication of matrices for transplantation in centers where there is a shortage of corneas, or where there is need for temporary patches to repair perforations in emergency situations. Copyright © Association for Research in Vision and Ophthalmology.
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| 7. |
- Panagiotopoulos, Marios, et al.
(författare)
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Stroma remodelling during healing of corneal surface irregularities induced by PTK
- 2007
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Ingår i: Acta Ophthalmologica Scandinavica. - : Wiley. - 1395-3907 .- 1600-0420. ; 85:4, s. 387-394
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To study the histopathology of the remodelling process in the stroma after excimer-laser-induced corneal irregular injuries.Methods: Seven New Zealand white rabbits received in one eye a transepithelial plano photoablation (60 µm) and an additional plano ablation (25 µm). On the denuded stroma, an electron microscopy specimen grid was placed and another 25 µm ablation was applied to produce surface irregularities. Dichlorotriazinyl aminofluorescein (DTAF) was then applied for 45 seconds. Another seven right eyes of seven rabbits were ablated the same way but without using the grid, resulting in a plano ablation. All the rabbits were killed at weekly intervals after treatment. The harvested corneas from both eyes were further processed for haematoxylin-eosin staining and were also stained with monoclonal antibodies directed against Ki-67 antigen and α-smooth muscle actin (α-SMA). All specimens were examined under light and fluorescence microscope.Results: The corneal wounds were covered by epithelium during the first week. The 25 µm × 25 µm × 25 µm stromal irregularities were clearly discernible up to 3 weeks after treatment, during which time they melted and disappeared. A homogeneous zone was formed in which stroma cells laid down an initially disorganized stroma. This was sharply visible under a fluorescence microscope as a dark area between the dichlorotriazinyl aminofluorescein (DTAF) fluorescent stroma and autofluorescent epithelium. Very little response was seen in the plano-ablated wound microscopically and in terms of positive stained cells.Conclusion: As the irregularities are flattened and the homogenous zone becomes repopulated with keratocytes forming extracellular matrix material (ECM), the cornea regains its previous architecture in both groups. The irregular wound surface promotes wound-healing reactivity, a process that allows the cornea to compensate for the irregularities and heal to a functional state.
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| 8. |
- Weber, Beat A, et al.
(författare)
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Short-term impact of corticosteroids on hyaluronan and epithelial hyperplasia in the rabbit cornea after photorefractive keratectomy
- 2001
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Ingår i: Cornea. - : Ovid Technologies (Wolters Kluwer Health). - 0277-3740 .- 1536-4798. ; 20:3, s. 321-324
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Tidskriftsartikel (refereegranskat)abstract
- Purpose. To investigate the impact of corticosteroids on subepithelial hyaluronan deposition and corneal epithelium thickness in the first 10 days after photorefractive keratectomy (PRK) and to analyze a possible contralateral effect of corticosteroids. Methods. Thirty-two New Zealand white rabbits were assigned into two groups and had a transepithelial 5.0-mm diameter, 8.00-diopter myopic PRK performed on one eye. The corticosteroid treatment group (16 animals) received 0.1 mL of methylprednisolone 4% subconjunctivally on the operation table, followed by 0.1% dexamethasone eye drops six times a day during the postoperative period. The sodium chloride (NaCl) treatment group received topical isotonic NaCl eye drops six times a day. In each treatment group, eight animals were killed after 3 and 9 days, respectively. The harvested specimens were stained for hyaluronan and the epithelial thickness was measured. Results. In contrast to the epithelial thickness, the subepithelial hyaluronan did not show a significant increase during the observation period. The corticosteroid treated group showed at both time-points significantly less subepithelial hyaluronan formation as well as a significantly thinner epithelium, when compared with the NaCl-treated group. At 9 days, the corticosteroid-treated group showed a mild epithelial hyperplasia in only one of eight eyes, whereas this was a common finding in the NaCl-treated group. We detected no hyaluronan deposits in any contralateral-untreated eye, and the epithelial thickness did not differ significantly between any of the four contralateral-untreated eye groups. Conclusions. Corticosteroid medication during the first 10 days after operation reduces the amount of subepithelial hyaluronan production and inhibits the epithelial proliferation, and epithelial hyperplasia is prevented. Neither a contralateral hyaluronan deposition nor a contralateral corticosteroid effect could be detected.
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| 9. |
- Weber, Beat A, et al.
(författare)
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Wound healing response in the presence of stromal irregularities after excimer laser treatment
- 2001
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Ingår i: Acta Ophthalmologica Scandinavica. - : Wiley. - 1395-3907 .- 1600-0420. ; 79:4, s. 381-388
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To trace the fate of stromal irregularities after excimer laser treatment and to increase our knowledge of the reasons why surface irregularities in the ablation bed cause inferior postoperative results. Methods: Twelve New Zealand White rabbits received a transepithelial photoablation to a preset depth of 60 ╡m. An electron microscopy specimen grid was then placed on the denuded stroma and another 20 ╡m ablation was applied in order to produce surface irregularities. Another six rabbits received a plano transepithelial photoablation to a preset depth of 80 ╡m. The treated corneas were harvested at various timepoints and differentially further processed for microradiography, hematoxylin-eosin-, hyaluronan (HA)- and leukocyte protein L1 staining. Results: In the grid treated corneas the subepithelial mesh pattern is clearly discernible after 1 week, and after 4 weeks it is replaced by a subepithelial layer containing HA and water. The thinning of this layer between 1 and 12 weeks is statistically significant (p<0.05). After 4 and 8 week the plano treated corneas only exhibit some subepithelial HA- and water accumulation. After 1 day the grid treated corneas show an extensive stromal infiltration of leukocytes. In the plano treated corneas the leukocytes mainly remain on the surface. Conclusions: During the healing process stromal irregularities are flattened, leaving a homogeneous zone with increased water content. This subepithelial layer is rarefying as new subepithelial tissue is forming. Postablational irregularities induce a more pronounced healing reaction when compared to a smooth ablation surface. Leukocyte infiltration seems to play a role in this process.
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