Photoreceptors Repair by Autologous Transplantation of Retinal Pigment Epithelium and Partial-thickness Choroid Graft in Rabbits

Purpose: To investigate whether autologous retinal pigment epithelium (RPE) and a partial-thickness graft can repair degenerated photoreceptors overlying a mechanically damaged Bruch's membrane.

Methods: Twenty-one pigmented rabbits were used in the study. Abrasive debridement of the RPE was performed with a metal cannula after superior retinal bleb detachment in 20 rabbits. The graft was prepared beneath the inferior retina and was transplanted to the debridement area 14 days later. Debridement-only sites served as the control. Tissue sections were evaluated by light microscopy and transmission electron microscopy at 7 days, 1 month, and 3 months after transplantation, corresponding to 21 days, 45 days, and 3 months after debridement, respectively.

Results: When analyzed at 7 days after transplantation, short buds of inner segment with regularly organized outer nuclear layer were observed. The outer segments (OS) were of insufficient length to be observed, but by 1 and 3 months, a significant elongation of the OS was detected. In control retinas from 21 days (corresponding to 7 days after transplantation) to 3 months after RPE debridement, the outer nuclear layer cells were disorganized and diminished.

Conclusions: This study showed that autologous RPE and partial-thickness choroid graft have the capacity not only to support photoreceptor cell survival, but also to initiate early repair mechanisms, as exhibited by outer segment regeneration.