Long-term outcome of RPE allografts in non-immunosuppressed patients with AMD

To determine the long-term outcome of human retinal pigment epithelium (RPE) transplants in patients with advanced age-related macular degeneration (AMD).

Using pars plana microsurgical techniques, RPE allografts were transplanted subretinally to four groups of AMD patients: five patients received organized patch transplants after removal of choroidal neovascular membranes, four got small patch transplants in dry AMD; suspensions of RPE cells were transplanted in five cases with dry AMD, and two patients with RPE tears. None received immunosuppression. Transplants were followed for 24-38 months by biomicroscopy, fundus photography, SLO microperimetry, and fluorescein angiography. Rejection was defined as loss of visual function over the transplant, development of an exudative response (subretinal fluid with or without neovascularization), fluorescein leakage, and disruption, depigmentation, or encapsulation of the transplant.

Four of 16 transplants (25%) presented no clinical signs of rejection. Three of the four small patch transplants remained pigmented and essentially unchanged after 30-32 months. Clinical signs of graft rejection appeared within three months in all cases of neovascular AMD (disrupted blood-retinal barrier, BRB), but after 6-20 months in five of nine eyes with non-exudative AMD (intact BRB).

Subretinal human RPE allografts present a high rejection rate (75%) without immunosuppression. However, small extrafoveal transplants remained unchanged in shape, size and color for more than two years in non-exudative AMD. A disrupted BRB is likely to enhance graft rejection, which occurs earlier in exudative than in non-exudative AMD.