Purpose: To determine if retinal pigment epithelium (RPE) transplantation maintains visual function in Royal College of Surgeons (RCS) strain of rats.
Methods: Twelve RCS rats received RPE transplants at 16 to 20 days after birth. The retinas were studied electrophysiologically and histologically from 3 to 10 months after transplantation and compared with 11 RCS controls and 11 normal rats of comparable ages. A microelectrode was guided to the transplant site visible by its pigmentation in the albinotic RCS retina to detect responses.
Results: Spontaneous ganglion cell activity was present in all retinas. Ganglion cell responses to light were detected in 9 of the 12 transplant eyes but not in any of the 11 controls. 96, 44, 140 units were encountered and 30%, 0%, 97% were driven by light respectively in transplant, control, and normal retinas. In transplants 36%, 29%, and 28% were driven at 3 to 4, 6 to 7, and 10 months after transplantation, respectively. Intraretinal ERGs with both a- and b-waves were recorded in 5 of the 8 transplants studied. None of the RCS controls studied had an IERG. The average IERG was 2.5 microV (SD = 1.9) in transplants and 59 microV (SD = 19) in normal retinas. The electrode track was traced to the transplant site in six of the seven retinas that were responsive to light and examined histologically.
Conclusion: RPE transplants to RCS rats maintain retinal function in the transplant site for long periods of time.