Abstract
Abstract: :
Purpose: Synapse formation between transplanted neurons and remaining host neurons is believed to be a major obstacle to the success of neural retinal transplantation. This study evaluates synaptogenesis at the graft-host interface using labeled graft tissue and confocal immunofluorescent microscopy. Methods: Ten six-week-old rd (C3H/HeJ) mice were transplanted subretinally (transscleral approach) in one eye with small sheets/fragments of neural retinal tissue obtained from newborn normal enhanced green-fluorescent protein (eGFP) mice. At 8-12 weeks of age, the transplanted mice were anesthetized and the eyes were enucleated. The eyes were embedded in medium for frozen tissue and sections through the graft were processed for immunofluorescent microscopy using standard techniques. Sections were double-labeled with opsin and synaptophysin. Results: GFP-labeled grafted neurons were identified as a sheet located between the host inner nuclear layer and retinal pigment epithelium (RPE). Transplanted cells exhibited photoreceptor outer segments which stained positive for opsin. No migration of transplanted neurons into the host retinal layers was observed. Extensive synaptophysin staining was observed in the host inner plexiform layer. Significant synaptophysin staining was also detected between some cells in the host inner nuclear layer and between cells in the transplant. Only rare synaptophysin-positive processes were observed at the graft-host interface. Conclusion: Synapse formation at the graft-host interface appears to be limited following standard neural retinal transplantation. Immunofluorescent microscopy with labeled graft tissue, however, may serve as a useful method for evaluating the success of future studies aimed at improving graft-host synaptogenesis.
Keywords: 554 retina • 607 transplantation • 594 synapse