PEDF Promotes Retinal Neurosphere Formation and Expansion In Vitro
The retina is subject to degenerative conditions leading to blindness. Although retinal regeneration is possible in lower vertebrates, it does not occur in the adult mammalian retina. Retinal stem cell (RSC) research offers unique opportunities for developing clinical application for therapy. The ciliary body of adult mammals represents a source of quiescent RSC. These neural progenitors have a limited self-renewal potential in vitro but this can be improved by mitogens. Pigment Epithelium Derived Factor (PEDF), a member of the serpin gene family, is synthesized and secreted by retinal pigment epithelium (RPE) cells. We tested combinations of PEDF with fibroblast growth factor (FGF) during RSC growth to evaluate self-renewal and subsequent differentiation into retinal-like neuronal cell types. Medium supplemented with FGF + PEDF enhanced the RSC yield and more interestingly allowed expansion of the culture by increasing secondary retinal neurospheres after the 1st passage. This effect was accompanied by cell proliferation as revealed by BrdU incorporation. PEDF usage did not affect rod-like differentiation potential. This was demonstrated by immunofluorescence analysis of Rhodopsin and Pde6b that were found similarly expressed in cells derived from FGF or FGF + PEDF cultured RSC. Our studies suggest a possible application of PEDF in Retinal Stem Cell culture and transplantation.
KeywordsAlbumin Glycine Heparin Retina MgCl2
We are grateful to Fondazione Cassa di Risparmio di Modena for Dr De Marzo fellowship support and XIII International Symposium on Retinal Degeneration for her travel award grant. We acknowledge the CIGS of University of Modena for providing confocal microscopy assistance. This work was supported by research grants EVI-GENORET: LSHG-CT-2005-512036 from the European Community, by research grant GGP06096 from Fondazione Telethon and PRIN 2006053302_003.
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