PurposeAutologous retinal transplantation (ART) has been successfully employed in the treatment of large and myopic macular holes that are refractory to standard surgical treatments. Patients transplanted with a peripheral neurosensory retinal graft have shown unexpected improvements in visual acuity. The study aims to investigate if neural integration of the graft takes place in a porcine model of retinal hole. DesignExperimental animal study. SubjectsLeft eyes of ten Danish landrace pigs. MethodsThe pigs underwent vitrectomy under general anesthesia, and a subretinal bleb was created within the visual streak on both sites of the optic disc. A retinal hole, approximately 1900-4000 microns in size, was cut temporally using a vitrector. A graft of matching size was harvested from the nasal retina. The graft was gently moved toward the retinal hole under perfluoro-n-octane and placed within it. Endolaser was applied around the donor site, and either air or oil tamponade was used. Optical Coherence Tomography (OCT) and Color Fundus Photography were performed two and six weeks after surgery. At the end of follow-up, the eyes were enucleated for histological examination, including immunohistochemical analysis with antibodies against retinal glial cells, photoreceptors, and inner retinal neurons. ResultsRetinal hole closure was achieved in 9 out of 10 cases, with the graft remaining in situ in 6 cases. In 4 cases, OCT scans indicated preservation of the outer retinal layers, and in 2 of these cases, there was apparent integration with the adjacent host retina. Corresponding histology confirmed the preservation of the photoreceptor layer in 3 cases, but there was no evidence of graft integration with degeneration of the inner retina in all cases. The distance between the margins of the retinal hole decreased during follow-up, suggesting that the graft contracts and drags the surrounding retina towards the center. ConclusionThe outer retina of a retinal graft can be preserved, while the inner retina degenerates. No evidence of neuroretinal integration of the graft was observed. The retinal graft serves as a scaffold, promoting the centripetal migration of the edges of the hole, resulting in closure of large retinal holes.
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