TRANSPLANTATION OF RPE IN AGE-RELATED MACULAR DEGENERATION - OBSERVATIONS IN DISCIFORM LESIONS AND DRY RPE ATROPHY

A study was carried out to investigate whether human RPE allografts ar e tolerated or rejected in the subretinal space and to determine the f easibility of RPE transplantation in subjects with age-related macular degeneration (AMD). Methods: Patches of human fetal RPE (13-20 weeks of gestational age) were transplanted into the subretinal space of fiv e patients after surgical removal of subfoveal fibrovascular membranes , and to four subjects with dry geographic atrophy. Suspensions of RPE cells were transplanted to four other patients with nonexudative AMD. Results were evaluated with clinical ophthalmological examination, SL O microperimetry and fluorescein angiography over 8-20 months. Results : In disciform lesions, RPE transplants developed macular edema and fl uorescein leakage concomitant with gradual reduction of visual acuity, implying host-graft rejection, over 1-6 months. In geographic atrophy , three of four transplants showed little change in shape and size aft er 12 months (one transplant was slowly rejected). In non-exudative AM D, RPE suspension transplants showed no evidence of rejection and were associated with the disappearance of drusen; visual acuity remained s table and SLO microperimetry confirmed retinal function over the trans planted area. Conclusion: Human RPE allografts are not invariably reje cted in the subretinal space without immunosuppression. The rejection rate is lower in nonexudative than in neovascular AMD. An intact blood -retinal barrier is likely to protect against rejection. It is technic ally feasible to transplant human RPE into the submacular space withou t adversely affecting visual function in nonexudative AMD over relativ ely long periods of time.