gms | German Medical Science

Background: Previous studies have shown that transplanted autologous pigment epithelial cells in suspension are well tolerated, but do not result in significant functional improvement and several growth factors prevent or delay photoreceptor degeneration. We postulate that to achieve vision improvement in retinal degenerations, such as AMD, it will be necessary to transplant cells that can continuously deliver appropriate biological modifiers and are existent as a preformed monolayer. As the first step we have genetically modified RPE cells to stably produce and secrete the neurotrophic and anti-angiogenic factor PEDF using non-viral transfection protocols.

Methods: Using nucleofection primary pigment epithelial cells were transfected with plasmids encoding recombinant PEDF. The purified, secreted PEDF fusion proteins were identified by immunoblotting and their biological activity was determined by examining their effect on the up-regulation of ZIP2 mRNA expression using Real-Time PCR.

Results: Primary pigment epithelial cells were successfully transfected with efficiencies greater than 70%. The PEDF fusion proteins were secreted for the four month the cultures were followed as well as after 5 passages. The proteins were biologically active as evidenced by mRNA up-regulation of the zinc transporter protein ZIP2 in cultured ARPE-19 cells.

Conclusions: We have shown that using nucleofection it is possible to insert the PEDF gene in pigment epithelial cells with efficiencies of approximately 80%. At this time the transfected cells have secreted biologically active PEDF for extended four months and after 5 passages, suggesting integration of the transfected gene into the host cell genome.