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Impressum
Long Term Transgene Expression in Iris Pigment Epithelial Cells Transplanted into the Subretinal Space
Luther T. T., Semkova I., Kirchhof B., Schraermeyer U.
University Eye Hospital Cologne, Joseph-Selzmann-Str. 9, 50931 Cologne, Germany
Objective: Iris pigment epithelial (IPE) cells and retinal pigment
epithelial (RPE) cells have a common embryonic origin. They share different
properties including rod outer segment phagocytosis and production of
growth factors. IPE cells have been used as RPE replacement in patients
with age related macular degeneration (ARMD) with limited success rates.
In this study we examined the expression of the reporter gene enhanced
green fluorescent protein (EGFP) in transduced IPE cells, which were transplanted
to the subretinal space.
Material and Methods: IPE cells from Long-Evans rats were harvested
and cultured. The cells were transduced using AdFK7, an adenovirus vector
expressing the EGFP gene from the human CMV promoter, at a multiplicity
of infection (MOI) of 200. 6x105 cells in a volume of 0.5 µl were
injected subretinally into eyes of Wistar rats. EGFP expression was monitored
by scanning laser ophthalmoscopy (SLO) and fluorescence stereo microscopy.
After 4 months the eyes were enucleated and examined using (fluorescence)
light microscopy.
Results: The transduction rate of IPE cells with 200 MOI of AdFK7
in vitro was 100%. EGFP fluorescence was detectable 24 hours post transduction.
Following IPE transplantation repeated SLO and fluorescence stereo microscopy
examimations showed strong EGFP signals in the region of transplanted
IPE cells. The expression was stable over the study period of four months.
After enucleation a good integration of IPE cells into the RPE layer was
noted. IPE cells were still expressing the EGFP transgene. There was no
evidence of IPE cell rejection.
Conclusion: IPE cells can be efficiently and stably transduced
by adenovirus vectors. Long term expression of the reporter gene was achieved
in the subretinal space of rat hosts. These findings encourage the use
of transduced IPE cells in diseases such as ARMD complicated by CNV. Photoreceptor
rescue potentially is further enhanced by IPE transduction with neurotrophic
factors prior to subretinal transplantation.