Absorbable sandwich-like membrane for retinal-sheet transplantation.

Neural retinal transplantation has great potential for the alleviation of different degenerative and hereditary retinal disorders. However, because of the fragile and soft nature of retina, retinal-sheet transplantation is relatively difficult to achieve. To overcome this difficulty, we developed a technique for lamellar tissue transplantation. Biodegradable gelatin membranes were fabricated into a sandwich and encapsulated retinal grafts for transplantation. Before transplantation, we characterized the in vivo and in vitro properties of such membranes to determine the optimal sterilization procedure, that is, a sterile membrane with suitable degradability and good mechanical properties and without cytotoxicity. Three sterilization methods were conducted, with hydrogen peroxide gas plasma (HPGP), ethylene oxide (EO), and gamma-ray irradiation (gamma). The results were compared with those of a control (no disinfection). Initial studies revealed that the gelatin membranes sterilized with HPGP or EO exhibited retinal pigment epithelium (RPE) cytotoxicity, whereas the membrane sterilized by 16.6-kGy gamma ray irradiation had no RPE cytotoxicity and had enhanced mechanical properties. In the in vivo rabbit study, implanted gelatin membranes demonstrated satisfactory biocompatibility without any inflammation. Transplanted retinal sheets survived well and developed laminar structures. Such a method using gelatin membranes for tissue transportation has great potential for future routine retinal-sheet transplantation. Copyright 2002 Wiley Periodicals, Inc.