Subretinal Amniotic Membrane Transplantation in a Porcine Model of Retinal Hole

To investigate the histopathological changes following subretinal amniotic membrane transplantation in an in vivo porcine model of retinal holes.

Left eyes of 12 Danish Landrace pigs were vitrectomized under full anesthesia. A subretinal bleb was created before excising a retinal hole (1154-2934 µm) using a 23-gauge vitrector. The pigs underwent transplantation of human freeze-dried amniotic membrane into the subretinal space, with no tamponade applied. Optical coherence tomography and color fundus photography were performed just after surgery and at 2 and 4 weeks post-surgery. At the end of follow-up, the eyes were enucleated for hematoxylin and eosin staining and fluorescence immunohistochemistry, using antibodies against retinal glial cells and inner retinal neurons.

The amniotic membrane sheets facilitated hole closure by gliosis and centripetal migration of the edges of the hole. Immunohistochemical examination showed that the cells within the closed hole expressed anti-glial fibrillary acidic protein (GFAP) and anti-S100B, but not anti-glutamine synthetase (GS), suggesting that astrocytes were the predominant glial cells involved in hole closure. Gliosis was observed between the amniotic membrane sheet and the overlying photoreceptors of the surrounding retina. Morphological restoration of the retinal layers within the closed retinal hole was not observed.

The amniotic membrane acted as a stimulator for retinal hole closure by inducing glial cell proliferation and providing a scaffold for the centripetal migration of the edges of the hole. No morphological restoration was observed.