Transplant of full-thickness embryonic rabbit retina using pars plana vitrectomy

PURPOSE: To develop an improved surgical technique making full-thickness retinal transplant possible, thereby achieving a normal laminated transplant with minimal rosette formation.METHODS: A total of 23 rabbits underwent vitrectomy, retinotomy, and subsequent subretinal transplant of a complete embryonic neuroretina using a specially crafted glass cannula. Of the 23 animals, 15 received a prenatal day 16 or 19 (E16 or E19) retina; the remaining eight received an E15 retina. The animals were followed from 10 to 35 days, and after this period, the transplants were sectioned and stained for light microscopy.RESULTS: In 11 of the 15 transplants with E16 or E19 donors, histology showed regions up to 1.8 mm of straight, correctly positioned transplants with layering corresponding to their age. The eight animals kept alive longest postoperatively, 31 or 35 days, all showed normal retinal layers, including photoreceptor outer segments appositioned against the host retinal pigment epithelium. Tissue from the youngest donors (E15) yielded less well-organized transplants, indicating a critical stage in retinal embryogenesis before which transplant in this respect is less favorable.CONCLUSIONS: Our procedure makes it possible to transplant embryonic retina to the appropriate position adjacent to the host retinal pigment epithelium, keeping the transplant architecture intact. The transplants show good layering and well-developed photoreceptors abutting the retinal pigment epithelium