[Subretinal transplantation of confluent pigment epithelium: a novel device for non-traumatic tissue handling]. / Subretinale Transplantation von konfluentem Pigmentepithel: Ein neues Instrument zur atraumatischen Gewebeaufnahme.

BACKGROUND: Subretinal transplantation of pigment epithelium may be a therapeutic option in the treatment of age-related macular degeneration. Suspensions of pigment epithelial cells as well as confluent cell layers are being considered. METHODS: We developed a surgical device which permits to load living tissue, without exerting mechanical stress to the cells themselves, and to deliver it precisely onto the subretinal target site. RESULTS: After having been grown to confluency on extracellular matrix, the tissue can be fixed on a cannulated spoon by creating a vacuum on its undersurface. The spoon is connected to a silicone tube attached to a syringe. The syringe is used to produce a vacuum which is delivered to the tissue through the perforated surface of the spoon. After directing the spoon into the subretinal space, the tissue can be discharged by releasing the vacuum. CONCLUSIONS: In previous studies large cannulas have been used for injecting coherent cell layers underneath the retina. This technique frequently resulted in major distortion of the tissue. Furthermore, correct apico-basal orientation of the tissue often could not be achieved. We present a novel concept of a device which exerts vacuum to the entire underside of the graft allowing to hold it in position without distorting it. By releasing the vacuum, the graft can be positioned in the site of RPE atrophy. (Patent Reg. No. 29819018.4, München, Germany, 1998).

[Autologous subretinal transplantation of cultivated porcine iris pigment epithelial cells (IPE)]. / Autologe subretinale Transplantation von kultivierten porzinen Irispigmentepithelzellen (IPE).

BACKGROUND: Subretina transplantation of epithelium may be a therapeutic option for surgical treatment of age-related macular degeration (AMD). Various experimental data have demonstrated that homologous transplantation of retinal pigment epithelium (RPE) can prevent photoreceptor deterioration. However, most investigators experienced immunogenic graft rejection when using homologous pigmented cells for grafting. Autologous cells were soon considered as an alternative for subretinal grafting. Particularly iris pigment epithelium (IPE) appeared suitable to replace homologous RPE for it embryogenetic similarity and its simple availability. Recent studies have shown, that IPE is capable of taking over functions of RPE in maintaining retinal metabolism. the purpose of this study was to evaluate if autologous IPE cells would survive when being transplanted subretinally. In addition, immunogenic reponses to the presence of "foreign" iris pigment cells needed to be excluded. MATERIALS AND METHODS: Iris tissue was obtained by peripheral iridectomy in the anesthetized pig. Sheets of pigment iris epithelium were separated from the specimens and transferred into tissue culture. After the cells had been grown to confluency, cell suspensions were injected into the subretinal space of the donor animal's fellow eye. After 4 weeks, the grafted eye was enucleated and examined histologically.. RESULTS: The histological exam revealed that the graft cells had survived in the subretinal space. No evidence of immunogenic rejection was observed. CONCLUSION: Autologous IPE-cells can survive in the host's sub-retinal space without creating inflammatory reactions. Transplanted IPE appears to interact with photoreceptor outer segments.