Abstract
Purpose: :
Retinal pigment epithelial (RPE) cells provide support for photoreceptor cells and other neural retina cells in vivo, however, the detailed mechanism of this effect remain to be elucidated. This study is focused on evaluating the in vitro effect of different RPE conditioned mediums (RPE-CM) on the growth and differentiation of human retinal progenitor cells (RPC).
Methods: :
1). RPC isolation: RPCs were isolated from human fetal retinas at 18-20 gestational weeks, and cultured in suspension to form neurospheres in RPC medium. 2). Induction of RPC differentiation: The RPCs were transferred and cultured on fibronectin coated culture dishes up to 21 days with addition of 50% conditioned mediums from cultures of ARPE19, fetal RPE (fRPE) or HEK293 cells. 3). Immunofluorescent staining: The RPCs were stained by immunofluorescent methods to show the expression of differentiation related proteins found in specific retinal cells.
Results: :
The density of RPCs cultured in fRPE conditioned medium for 3 weeks was 5 times higher than that of RPCs cultured in RPC medium only or 4 times higher than that of RPCs cultured in HEK293 conditioned medium, respectively. More neuron-like cells (MAP2 positive cells) were observed in RPCs cultured with fRPE or RPE conditioned mediums. In contrast, more Muller cells (Glutamine synthetase positive cells) were observed in RPCs with RPC medium only or with HEK293 conditioned medium.
Conclusions: :
RPE-CM and especially fRPE-CM can promote RPC growth and induce RPC differentiation into neuron-like cells in vitro, suggesting that in vivo, RPE may similarly secrete bioactive factors to protect retinal cells and/or increase their growth, and to promote the differentiation of RPC into mature neural retinal cells.
Keywords: age-related macular degeneration • retina • retinal pigment epithelium