Pigmented epithelial cells ARPE-19 and docosahexaenoic acid promote cell differentiation and spatial organization of retina photoreceptors in vitro.

POLITI L, GERMAN L., ROTSTEIN, NP; , RODRÍGUEZ- BOULAN E., BUZZI E

Florida

Congreso; ARVO Meeting; 2007

ASSOCIATION FOR RESEARCH ON VISION AND OPHTHALMOLOGY (ARVO)

Pigmented Epithelial Cells ARPE-19 And Docosahexaenoic Acid Promote Cell Differentiation And Spatial Organization Of Retina Photoreceptors In Vitro Politi Luis(1); German, Lorena. (1); Rotstein Nora (1);  Rodríguez-Boulan, Enrique. (2)  Buzzi, Edgardo. (1) (1)INIBIBB, UNS-CONICET. 8000 Bahía Blanca and (2) M. Dyson Vis. Res. Inst. Cornell Univ., NY, USA. inpoliti@criba.edu.ar  Purpose: Retina photoreceptors depend on the continuous supply of several cellular and molecular cues. Interaction with retinal pigment epithelial (RPE) cells is essential for their functionality and docosahexaenoic acid (DHA) is required for their survival and differentiation. However, the benefits obtained from RPE cells depend on the establishment of a very precise spatial arrangement of photoreceptors and RPE cells in the retina. Up to now, how the interactions between these cell types contribute to establish the spatial arrangement during retina development is not completely understood. Methods: To investigate the interactions between RPE and photoreceptors, and the effects of DHA on these cells during their early development, we performed cocultures of retinal neurons with ARPE-19 cell line, supplemented with or without (control) DHA. The use of RPE-photoreceptor cocultures offer the advantage of experimentally altering the spatial organization naturally occurring in vivo, thus allowing investigating whether RPE cells and/or PHRs contribute to the acquisition of the spatial organization and the apical orientation found in the in vivo retina. Results: When pure retinal neurons were cultured with ARPE-19 epithelial cells, strict topological restrictions were observed. When neurons were seeded over RPE cells, photoreceptors attached to the epithelial apical surfaces as occurs in vivo. 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, a process that was blocked by the metalloproteinase inhibitor TIMP-1, suggesting that metalloproteinases might participate in this reorganization. Epithelial cells guided the outgrowing photoreceptor axons away from RPE cells, protected photoreceptors from apoptosis and enhanced their differentiation. DHA, which also promoted photoreceptor survival and differentiation in pure neuronal cultures, did not further enhance these effects when added to co-cultures. However, its addition increased the uptake of photoreceptor opsin by RPE cells. Conclusions: These results suggest that RPE cells might participate in establishing the process of pattern formation of the retina. The mutual interplay between these cells and DHA might also contribute not only to enhance RPE differentiation but also to regulate photoreceptor survival and differentiation.