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K. A. Kobuch, J. Storsberg, W. A. Herrmann, A. Messner, G. Duncker, S. Foja, S. Sel; Towards an Artificial Cornea: Evaluation of a New Designed Hydrophobic One-Material Implant With Modified Surfaces in vitro and in vivo. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5706. doi: https://doi.org/.
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To improve biointegration, stability, optical properties and thus the long-term clinical benefit of artificial keratoprotheses, we developed and evaluated a new type of implant on a hydrophobic base and innovative nanotechnology for local surface modifications.
A one-material implant from hydrophobic BENZ (HF-1) was designed with a total diameter of 10 mm, an optic centre of 4 mm, a haptic skirt of 3 mm and a central thickness of 2mm. The surface of the optic and haptic part was modified corresponding to the different requirements: after plasma-pretreatment, the skirt was coated in a layer by layer technique with different cell-adhesion promoting proteins. The optic part remained hydrophobic at the posterior side and was coated hydrophilic at the anterior part. The implants were tested with corneal epithelial cells in vitro for cell-adhesion and proliferation on the different coated areas (light-microscopy) and for biocompatibility (Trypan-blue dye exclusion). Implantations in rabbit eyes (n=8) were performed, applying an epicorneal fixation-technique with 4 sutures and covering with tissue from the eyelid.
In vitro experiments showed no cell-toxicity of the implants. The procedure of surface-modification in the different areas of the implant proved to be successful. The haptic skirt showed the expected cell-adhesive properties, whereas the optic part remained cell-free in vitro (4 days, 8 days) as well as in vivo (up to 6 weeks). Among 5 different coatings of the haptic part: coating with fibronectin like-protein as the outest layer showed excellent adhesion and proliferation of corneal epithelial cells and, thus, qualified for the use on implants for animal experiments.
By using special nanotechniques for surface-modification, the hydrophobic implant-material could be adapted to meet demands for biointegration in the haptic part and cell-free transparency in the optic part. Fibronectin could be identified as an adequate coating for the haptic by promoting cellular adhesion and proliferation. Furthermore, the design of this type of implant proved to be appropriate for surgical epiretinal implantation and postoperative corneal stability. If epithelisation in vitro correlates with biointegration and sufficient mechanical strength in vivo needs further investigation.
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