The transplantation of human fetal neuroretinal cells in advanced retinitis pigmentosa patients: Results of a long-term safety study

The purpose of this study was to determine the long-term safety of transpla nting human fetal neuroretinal cells (14 to 18 week gestational age) into a series of patients with advanced retinitis pigmentosa (RP). After obtainin g informed consent, both hosts and mothers of donors were screened for tran smissible diseases. Pre- and postoperative clinical exams, visual acuity, e lectroretinograms, and fluorescein angiograms were performed and visual fie ld testing was attempted in each case. Surgically, an anterior approach thr ough pars plana ciliaris was used. A retinotomy was performed in the parama cular area and a two-function cannula was introduced into the subretinal sp ace to deliver a suspension of donor cells. The cell suspension carried app roximately 4000 cells/mu l; the volume injected did not exceed 150 mu l. Th e patients were examined for periods ranging from 12 to 40 months posttrans plantation. To date, no evidence of inflammation, infection, or overt rejec tion of the graft was noted in the host eye, neither was any change observe d in the contralateral, unoperated eye. In conclusion, neuroretinal cells w ere injected into the subretinal space of 14 patients with advanced RP with no clinical appearance of detrimental effects at the time of surgery or up to 40 months postinjection except in 1 patient who developed retinal detac hment. This sets the stage for a phase II clinical trial to determine the p ossible beneficial effects of this procedure in patients blinded by degener ative retinal disease. (C) 1999 Academic Press.