Distribution of sparc in PVR epiretinal membranes and production of sparc by cultured human retinal pigment epithelial cells

Abstract

Purpose SPARC (secreted protein acid rich in cysteine) is believed to modulate cell adhesion to the extracellular matrix We investigated the hypothesis that SPARC is associated with migratory retinal epithelial cells in proliferative vitreoretinopathy (PVR) epiretinal membranes and that cultured human retinal pigment epithelial (HRPE) cells may synthesise SPARC Methods Light microscopic immunohistochemistry was used to examine epiretinal membranes for the presence of SPARC and migratory HRPE whilst combined with immunoblotting and immunoprecipitation, the possible production of SPARC by HRPE vitro was examined. Results SPARC immunostaining was observed associated with migratory HRPE (identified through the expression of a migration-related epitope expressed on RPE cytokeratin 18) in epiretinal membranes In cultures of HRPE the production of SPARC was identified as a band in cell lysates and conditioned media. Conclusions Our results suggest that HRPE are capable of SPARC synthesis The association between SPARC and migratory RPE cells in epiretinal membranes may indicate an important role for this matricellular protein in PVR development. Supported by the Guide Dogs for the Blind Association, North West Regional Health Authority and The Royal College of Surgeons of Edinburgh. None.