α-Melanocyte-stimulating hormone prevents glutamate excitotoxicity in developing chicken retina via MC4R-mediated down-regulation of microRNA-194.

Glutamate excitotoxicity is a common pathology to blinding ischemic retinopathies, such as diabetic retinopathy, glaucoma, and central retinal vein or artery occlusion. The development of an effective interventional modality to glutamate excitotoxicity is hence important to preventing blindness. Herein we showed that α-melanocyte-stimulating hormone (α-MSH) time-dependently protected against glutamate-induced cell death and tissue damage in an improved embryonic chicken retinal explant culture system.

Role of autophagy in photoreceptor cell survival and death.

Autophagy, a highly conserved self-degradation process that occurs under both physiological and pathological conditions, provides the raw material and energy for cell regeneration under normal circumstances. Dysregulated autophagy under diseased conditions may cause protein accumulation, organelle dysfunction, and even cell death. Recent studies have shown that autophagy regulates the structural integrity and physiological functions of retinal photoreceptor cells and contributes to the pathogenesis of retinopathies such as retinal detachment, age-related macular degeneration, retinitis pigmentosa, and Leber's congenital amaurosis.

Development of retinal pigment epithelium from human parthenogenetic embryonic stem cells and microRNA signature.

Purpose: We investigated the potential of human parthenogenetic embryonic stem cells (hPESCs) to differentiate into RPE cells, and identified development-regulating microRNAs (miRNAs).

Methods: RPE cells were derived from hPESCs. The expression of markers and miRNA expression profiles during differentiation were studied by immunocytochemistry, real-time RT-PCR, and miRNA expression array at three time points.

MicroRNA-204/211 alters epithelial physiology.

MicroRNA (miRNA) expression in fetal human retinal pigment epithelium (hfRPE), retina, and choroid were pairwise compared to determine those miRNAs that are enriched by 10-fold or more in each tissue compared with both of its neighbors. miRs-184, 187, 200a/200b, 204/211, and 221/222 are enriched in hfRPE by 10- to 754-fold compared with neuroretina or choroid (P<0.05).

PDGF-C and -D induced proliferation/migration of human RPE is abolished by inflammatory cytokines.

Purpose: The role of growth factors and inflammation in regulating retinal pigment epithelial (RPE) function is complex and still poorly understood. The present study investigated human RPE cell proliferation and migration mediated by platelet-derived growth factor (PDGF) and inflammatory cytokines.

Methods: Human fetal RPE (hfRPE) cells were obtained as previously described.

Confluent monolayers of cultured human fetal retinal pigment epithelium exhibit morphology and physiology of native tissue.

Purpose: Provide a reproducible method for culturing confluent monolayers of hfRPE cells that exhibit morphology, physiology, polarity, and protein expression patterns similar to native tissue.

Methods: Human fetal eyes were dissected on arrival, and RPE cell sheets were mechanically separated from the choroid and cultured in a specifically designed medium comprised entirely of commercially available components. Physiology experiments were performed with previously described techniques.