Full-thickness retinal transplants: A review

Embryonic full-thickness rabbit neuroretinal sheets were transplanted to th e subretinal space of adult hosts. This was accomplished by using a new tra nsplantation technique involving vitrectomy and retinotomy. The grafts were followed from 10 to 306 days after surgery and were then examined by diffe rent histological techniques. In the light microscope, the transplants were seen to develop the normal retinal lamination and fusion with the host ret ina, especially after long survival times. Ultrastructurally, normal photor eceptor outer segments, well integrated with the host retinal pigment epith elium, were found. Growth cones were present in the zone of fusion between graft and host retina. Immunohistochemical labeling revealed many of the no rmal retinal components not previously found in retinal transplants, and gr aft-host connections between neurons in the rod pathway were seen. The morp hology of vibratome-sectioned neuroretinal sheets as well as adult full-thi ckness grafts was also examined. These transplantation types showed less of the normal morphology compared with embryonic full-thickness grafts, The i mmunogenicity of embryonic full-thickness and fragmented grafts was compare d using major histocompatibility complex immunolabeling. Fragmented grafts elicited a response from the host immune system similar to a chronic transp lant rejection. This reaction was absent in the full-thickness grafts which is in accordance with their good long-term survival. Copyright (C) 2000 S. Karger AG, Baser.