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B.S. McKay, E. Erbe, D. Rak, S. Sherman; Pigmenting RPE Secrete Neurotrophic Agents . Invest. Ophthalmol. Vis. Sci. 2004;45(13):630.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Alterations in retinal pigment epithelial cell (RPE) pigmentation lead to changes in retinal development that cause the visual deficits in albinism. This suggests that pigmenting RPE may secrete agents that alter neuronal differentiation. In this study we test whether culture medium from pigmenting RPE cultures affect the differentiation or survival of cultured developing neurons. Methods: Human RPE cultures were maintained under standard conditions, then pigmenting and nonpigmenting (control) cultures were produced using a Ca++–switch paradigm. Rat retinal and midbrain neurons were harvested from E15–E17 day rats, grown for 4 days then treated with antiproliferative agents. Cells were maintained in either basal medium, or treated with RPE conditioned medium from pigmenting or control nonpigmenting cultures. Neuronal differentiation was assessed by staining with antibodies to neuronal markers. Neurons were counted and axonal projections were measured for length. Results: RPE conditioned medium collected from pigmenting RPE cultures has a significant effect on the number of neurons per field surviving at day 14 (p=.002) and on the length of the longest neurite (p=.024) when compared to paired neuron cultures treated with RPE conditioned medium from nonpigmenting cultures. Results comparing neuron survival were variable potentially due to the variability of the pigmentation in RPE cultures after the Ca++–switch or the time at which the medium was collected after the switch. Conclusions: RPE conditioned medium from cultures actively producing pigment promote neuronal differentiation and axonal projection whereas medium from paired RPE cultures not producing pigment had no effect. This suggests that during pigmentation, RPE cells secrete agents that affect neuronal development, and offers a new model system for the study of ocular albinism.
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