PURPOSE. TO determine whether human retinal pigment epithelium (RPE) can be
modified by retroviral-mediated gene transfer and to monitor the human RPE
cells in the subretinal space of living rabbits with scanning laser ophtha
lmoscopy (SLO).
METHODS. Cultured human fetal retinal pigment epithelium (HFRPE) was expose
d to green fluorescent protein (GFP)-transducing retroviral vectors, Molone
y murine leukemia virus, and lentivirus. The cultured cells were followed b
y fluorescence microscopy. Suspensions of GFP-expressing HFRPE were transpl
anted into the subretinal space of pigmented rabbits, and the transplant si
tes were examined by SLO for fluorescence, including fluorescein and indocy
anine green angiography. The rabbits were euthanatized at different times a
fter transplantation, and the retinas were studied histologically.
RESULTS. Retroviral gene transfer can introduce a foreign gene such as GFP
into cultured HFRPE. Gene expression is maintained in cultured RPE for at l
east 3 months. The lentiviral vector traduced both nondividing and dividing
cells; the Moloney vector only transduced the latter. GFP-expressing cells
can be followed in the living retina. Their changes reflect the rejection
response followed histologically.
CONCLUSIONS. Cultured HFRPE could be transduced to express GFP for long per
iods of time by retroviral gene transfer. GFP allowed retinal transplants a
nd gene expression to be monitored in vivo. These results provide a model f
or potential ex vivo gene therapy in the subretinal space.