Abstract

DO.23.01

RPE transplantation: Does it have a future?

Gouras P.
Columbia University New York

Being able to re-establish a healthy RPE monolayer that totally replaces a degenerate one could correct several macular degenerations: age related macular degeneration (AMD) Stargardt’s dystrophy, vitelliform macular degeneration or Leber’s amaurosis due to defects in the RPE 65 gene. But accomplishing the surgery this strategy requires is difficult, perhaps beyond current vitreal retinal methods. Nevertheless it is not unproductive to speculate on what might be needed to accomplish this feat. I believe there are four major challenges. 1. Access to the macula. 2. Removal of the degenerate RPE layer. 3. Replacement with a monolayer that covers the area denuded. 4. Elimination of rejection. Access: I suggest that the best way to do this is to perform a180 degree incision of the neural retina at the temporal ora rolling the retina nasally until the macular RPE is exposed. Removal: This would require extremely gentle suction or femto second laser disintegration of the layer without any perturbation of the choroid. Replacement: I suggest that a patch of cultured RPE be cut precisely to fit the gap, encased in gelatin, solid at room temperature, but fluid at body temperature This RPE unit must be inserted into the denuded area and captured by rolling the neural retina back over the macula and laser sealing it at the temporal ora to prevent subsequent detachment. Rejection: One thinks of stem cells but how to obtain them from a patient is a problem. I shall show you what RPE looks like in old and young retina near the ora to suggest that such RPE is not ideal, which is relevant to the strategies of Binder or van Meurs. We have discovered a phenomenon related to rejection of foreign proteins genetically transduced in RPE in vivo. Suppression must only be maintained for a relatively short period of time (a month) after the surgery necessary to introduce the foreign gene into the RPE and this prevents rejection permanently.

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