Search

Copyright of Bauphysik is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bauphysik is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Functional impairment of the human corneal endothelium can lead to corneal blindness. In order to meet the high demand for transplants with an appropriate human corneal endothelial cell density as a prerequisite for corneal function, several tissue engineering techniques have been developed to generate transplantable endothelial cell sheets. These approaches range from the use of natural membranes, biological polymers and biosynthetic material compositions, to completely synthetic materials as matrices for corneal endothelial cell sheet generation. This review gives an overview about currently used materials for the generation of transplantable corneal endothelial cell sheets with a special focus on thermo-responsive polymer coatings. [ABSTRACT FROM AUTHOR]

Copyright of Bauphysik is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bauphysik is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Gentle harvesting of corneal endothelial cell sheets grown in culture is of interest for the development of cornea replacement strategies. Thin films of a fast responding copolymer of N‐isopropylacrylamide (NiPAAm) and diethyleneglycol methacrylate (DEGMA) with a phase transition temperature of 32°C were prepared and evaluated for that purpose. The polymer layers were immobilized onto fluorocarbon substrates using low pressure argon plasma treatment. Cell culture and detachment experiments were performed with L929 mouse fibroblasts and human corneal endothelial cells (HCEC) at standard conditions. The hydrogel‐coated supports were found to permit adhesion, spreading, and proliferation of both cell types. Harvesting of cell sheets was achieved upon lowering the temperature to about 30°C. The formation of a closed monolayer as a crucial prerequisite for maintaining ionic pump function in HCEC was proven by ZO‐1 immunostainung. Labeling of fibronectin indicated that the vast majority of the extracellular matrix is detached from the hydrogel coatings together with the cell layer. Inspired by this result, the reuse of the hydrogel‐coated culture carriers was investigated confirming the suitability of the substrates for repeated cell harvesting. Altogether, the introduced thermoresponsive coating was found advantageous for the efficient generation of HCEC sheets and will be further utilized in transplantation strategies. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res 80A:, 2007 [ABSTRACT FROM AUTHOR]

Several hydrophilic, amphiphilic and thermoresponsive polymers are reported, which can be attached to polymeric substrates by using macroinitiators, 'grafting onto' processes or plasma and electron beam activation. Poly(acrylic acid) hydrogel layers grafted from a thin macroinitiator layer could be used to reduce the friction of polymeric catheters and to allow better sliding of the tubes into the blood vessels without damaging tissue. A similar approach could be used to fix hydrogel layers on balloon catheters, which are able to carry anticlotting drugs being released after the fixation of the catheter/stent within the blood vessel. A variety of amphiphilic graft copolymers and gels have been prepared based on oxazoline chemistry, which allows inducing heterogeneity into the gel structure leading to specific swelling properties. Copolymerization with N-isopropylacrylamide (NIPAAm) also incorporated thermoresponsive behaviour in the gels. Copolymers of NIPAAm with poly(ethylene glycol) macromonomers allowed the preparation of cell-compatible thermoresponsive materials immobilized on surfaces for cell release studies. [ABSTRACT FROM AUTHOR]

Two established material systems for thermally stimulated detachment of adherent cells were combined in a cross-linked polymer blend to merge favorable properties. Through this approach poly(N-isopropylacrylamide) (PNiPAAm) with its superior switching characteristic was paired with a poly(vinyl methyl ether)-based composition that allows adjusting physico-chemical and biomolecular properties in a wide range. Beyond pure PNiPAAm, the proposed thermo-responsive coating provides thickness, stiffness and swelling behavior, as well as an apposite density of reactive sites for biomolecular functionalization, as effective tuning parameters to meet specific requirements of a particular cell type regarding initial adhesion and ease of detachment. To illustrate the strength of this approach, the novel cell culture carrier was applied to generate transplantable sheets of human corneal endothelial cells (HCEC). Sheets were grown, detached, and transferred onto planar targets. Cell morphology, viability and functionality were analyzed by immunocytochemistry and determination of transepithelial electrical resistance (TEER) before and after sheet detachment and transfer. HCEC layers showed regular morphology with appropriate TEER. Cells were positive for function-associated marker proteins ZO-1, Na+/K+-ATPase, and paxillin, and extracellular matrix proteins fibronectin, laminin and collagen type IV before and after transfer. Sheet detachment and transfer did not impair cell viability. Subsequently, a potential application in ophthalmology was demonstrated by transplantation onto de-endothelialized porcine corneas in vitro. The novel thermo-responsive cell culture carrier facilitates the generation and transfer of functional HCEC sheets. This paves the way to generate tissue engineered human corneal endothelium as an alternative transplant source for endothelial keratoplasty. [ABSTRACT FROM AUTHOR]