A new method for subretinal transplantation of human cells as a thin layer in rabbit and porcine eyes

Abstract

 

Purpose

 

We recently showed that transplantation of human bone marrow mesenchymal stem cells as a thin subretinal layer in Royal College Surgeon (RCS) rats ameliorated retinal degeneration, rescuing photoreceptors along the entire retina. Here we developed a new surgical system for subretinal transplantation of cells in large eye models of rabbits and porcine as a step towards phase I clinical trials.

 

Methods

 

DiI-labeled human cells were transplanted into the subretina of New Zealand White rabbits and porcine, using a novel syringe system. In some cases cells were pre-labeled with near infra-red (NIR) ferumoxide nanoparticles. A longitudinal triangular scleral incision starting 4 mm away from the limbus at about 5°axis toward the choroid was formed. An additional tract through the choroid toward the retinal pigmented epithelium (RPE) was created by a bent wire. The cells were injected through the scleral tunnel and its extension. Spectral Domain Optical Coherence Tomography (SD-OCT, Heidelberg) equipped with a NIR camera was used for eye imaging and detection of transplanted cells. Eyes were inoculated for histology analysis shortly after OCT scans and cryopreserved. A fluorescent microscope was used to identify Dil-positive cells.

 

Results

 

Transplanted cells were identified shortly after transplantation as a uniform thin sheet of cells distributed along most of the subretina on the basal side of the RPE. These results correlate with OCT scans which detected the transplanted cells in a thin layer in a subretina - basal side of the RPE. No choroidal hemorrhage was observed.

 

Conclusions

 

This new surgical system allows therapeutic cells and agents to be in close proximity with the apical and basal side of the RPE in a thin layer with minimal retinal detachment. Furthermore the new surgical system allows introduction of therapeutic agents to the macula without insertion of surgical equipment into the macula. This study is expected to directly lead to phase I clinical trials for mesenchymal stem cell- based therapy in retinal dystrophy patients. Furthermore, implementation of this new transplantation technique may enhance the therapeutic effect of other cell-based therapies and therapeutic agents.

 

 

DiI-labeled human cells (red) transplanted into the subretina of New Zealand White rabbits as a thin sheet of cells distributed along the entire retina on the basal side of the RPE. RE-retina; CHR- choroid

 

Keywords: 721 stem cells • 741 transplantation • 412 age-related macular degeneration