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D.S. Rice, C. Sheridan, I. Grierson; The Vß5 Integrin: Comparison of Outer Sement Phagocytosis by IPE and RPE Cells . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3052.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:Age–related macular degeneration (AMD) is the commonest form of blindness affecting the elderly in the Western world. Dysfunction and death of the retinal pigment epithelium [RPE] is pivotal to the development and progression of AMD. RPE cell transplant is hindered by the risk of rejection. Iris pigmented epithelial (IPE) cells which share a common embryological origin with RPE cells have the potential to ingest photoreceptor outer segments (POS) and may provide an autologous alternative to RPE transplantation. The integrin αVß5 has been shown to be involved in the phagocytosis of POS by RPE cells and the aim of this study is to determine whether this integrin has a role in IPE phagocytosis. Methods:Bovine and human iris pigmented epithelial cells were dissociated from the iris by the agitation of 0.05% trypsin in PBS across the pigmented epithelium at 37oC and grown in F12 media with 30% serum. Cells were seeded onto 8–well chamber slides and probed with a monoclonal antibody against the αVß5 integrin (Covance). Visualization was by DAKO EnVision kit with fast red. Photoreceptor outer segments were retrieved from the neural retinas of bovine eyes and fluorescently labelled with SNAFL®–1 (mixed isomers). Phagocytosis by bovine IPE was assessed against that of RPE by the incubation with POS–SNAFL®–1 conjugate for various time intervals and analyzed using flow cytometry. Results:Both bovine and human RPE and IPE cells in vitro showed positive immuoreactivity for the integrin αVß5. All cell types showed a punctuate staining pattern on the apical surface of the cells with no difference observed between confluent and pre–confluent cells. All cell types also demonstrated staining with the antibody against the αVß5 integrin that increased in intensity with increasing passage of cells. Binding and ingestion of SNAFL®–1 labeled POS was observed within 10 minutes for both bovine RPE and IPE. After three hours incubation both bovine IPE and RPE showed no significant difference (p>0.05) in the levels of both ROS binding ROS and ingestion. Conclusions: Bovine IPE and RPE phagocytose POS in vitro and the presence of αVß5 integrin in all cell types studied indicates the process may be by a similar mechanism.
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