The human retinal pigment epithelial cell line ARPE-19 is polarized

Purpose. To determine if the human RPE cell line, ARPE-19 (Dunn et al., IOVS 36:S764), exhibits polarized structural and functional features. Methods. ARPE-19 cells were plated on permeable filter supports and examined by scanning and transmission electron microscopy. The distribution of several in vivo markers of polarity was examined using laser scanning confocal microscopy (LSCM). Results. Scanning electron microscopy of ARPE-19 cells revealed the presence of extensive microvilli on the apical surface. Staining of the apical surface with ruthenium red before TEM illustrated the presence of tight junctional complexes which were located at the apical pole of the cell. The presence of tight junctions was also confirmed by complete circumferential staining in a confocal X-Y scan of cells immunostained for ZO-1. Na, K-ATPase was localized preferentially to the basolateral surface, in contrast to the apical distribution found in vivo. We examined the ability of ARPE-19 cells to sort two well characterized apical markers, influenza HA, and p75-NTR. HA was introduced by infection with influenza virus, and p75-NTR by adenovirus-mediated gene transfer. Both HA and p75 were apically polarized. Conclusions. Our results demonstrate that monolayers of ARPE-19 exhibit polarized structural and functional properties similar to those of RPE cells in vivo. These data suggest that ARPE-19 cells may provide an excellent model to study the mechanisms by which human RPE aquire their unique polarity properties.