ARPE-19 Pigment Epithelial Cells And Docosahexaenoic Acid Promote Spatial Organization and Differentiation Of Retina Photoreceptors In Vitro

POLITI L.; GERMAN O. L.; ROTSTEIN N.; RODRÍGUEZ-BOULAND E.; BUZZI E.

Fort Lauderdale, Florida

Conferencia; The aging eye ARVO 2007 annual meeting; 2007

ARVO

Purpose: Retina photoreceptors depend on cellular and molecular cues for their development and function. Among others, docosahexaenoic acid (DHA) is required for their survival and differentiation, and interaction with retinal pigment epithelial (RPE) cells is essential for their functionality. This interaction depends on the establishment of a precise spatial arrangement between photoreceptors and RPE cells. We here investigated whether the interactions between both cell types contribute to establish this spatial arrangement and to promote photoreceptor development in vitro and whether DHA modulated these interactions.Methods: We used cocultures of rat retinal neurons and ARPE-19 cells. These cocultures allowed to experimentally alter the spatial organization occurring in vivo, by alternatively seeding photoreceptors on ARPE-19 cells or ARPE-19 cells on photoreceptors, and analyzing whether they reorganized their spatial localization. The effects of ARPE-19 cells on photoreceptor survival, differentiation and axonal outgrowth, in cocultures with or without DHA were also analyzed.Results: retinal neurons cultured with ARPE-19 cells showed strict topological restrictions. When neurons were seeded over RPE cells, photoreceptors attached to the epithelial apical surfaces as occurs in vivo, and no reorganization occurred. However, when epithelial cells were seeded over neurons, exposing to them their basal membranes, RPE cells rapidly detached photoreceptors from their substrata and positioned below them. This reorganization appeared to depend on metalloproteinases since it was blocked by the metalloproteinase inhibitor, TIMP-1. ARPE-19 cells promoted photoreceptor axonal outgrowth and oriented these axons away from RPE cells. They also protected photoreceptors from apoptosis and enhanced their differentiation. DHA, which promotes photoreceptor survival and differentiation in pure neuronal cultures, did not further enhance these effects in cocultures. However, its addition increased the uptake of opsin from photoreceptors by RPE cells. Conclusions: These results suggest that RPE cells might participate in establishing the process of pattern formation of the retina. The interactions between these cells and DHA might also contribute not only to enhance RPE differentiation but also to regulate photoreceptor survival and differentiation.