Phenotypic Plasticity of Retinal Pigment Epithelial Cells from Adult Human Eye In Vitro
17 Aug 2011-Bulletin of Experimental Biology and Medicine (Springer US)-Vol. 151, Iss: 4, pp 506-511
TL;DR: It was found that retinal pigment epithelium in adult human eye is a heterogeneous population of cells demonstrating different behavior in vitro, and irrespective of initial morphological features differentiation of Retinal pigment cells can be modulated by varying culturing conditions.
Abstract: Phenotypic plasticity of retinal pigment epithelial cells from adult human eye was studied by immunohistochemical methods under different culturing conditions. It was found that retinal pigment epithelium in adult human eye is a heterogeneous population of cells demonstrating different behavior in vitro. Some cells retain epithelial morphology for a long time in culture, while others are rapidly transformed into fibroblast-like cells and synthesize proteins typical of proneural, neural, glial, and photoreceptor cells. However, irrespective of initial morphological features differentiation of retinal pigment cells can be modulated by varying culturing conditions.
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TL;DR: In this review, data are presented on RPE cell sources for culture models, approaches to R PE cell culturing, phenotypic changes of RPE cells in vitro, the role of signal pathways, and possibilities for their regulation in pathological processes.
Abstract: The retinal pigment epithelium (RPE) plays a key role in the development of many eye diseases leading to visual impairment and even blindness. Cell culture models of pathological changes in the RPE make it possible to study factors responsible for these changes and signaling pathways coordinating cellular and molecular mechanisms of cell interactions under pathological conditions. Moreover, they give an opportunity to reveal target cells and develop effective specific treatment for degenerative and dystrophic diseases of the retina. In this review, data are presented on RPE cell sources for culture models, approaches to RPE cell culturing, phenotypic changes of RPE cells in vitro, the role of signal pathways, and possibilities for their regulation in pathological processes.
71 citations
Cites background or methods from "Phenotypic Plasticity of Retinal Pi..."
...Thus, adult rat RPE cells in culture were shown to express both neuronal markers—nestin, 𝛽-tubulin 3 (TUBB3), cortin, NG2, MAP2, and 200 kDa neurofilament protein (neurofilament 200)—and glial cell marker (GFAP) [85]....
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...Simultaneous expression of vimentin and intermediate filament proteins of other classes, nestin and GFAP, observed in RPE cell culture [26] is also characteristic of human neural stem cells [89]....
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...Suitable dissociation reagents include solutions of pronase, papain, trypsin, hialuronidase/collagenase, or dispase [20–24] or of nonenzymatic substances such as EDTA [25, 26]....
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...RPE cells in vitro also show positive staining for vimentin, a marker of intermediate filaments [26, 73]....
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...Typical supplements used in primary RPE cell cultures include basic fibroblast growth factor (bFGF) and optimized commercial mixtures such as N1 Supplement (containing transferrin, insulin, putrescine, progesterone, selenium, and biotin) or N2 Supplement (based on N1 Supplement without biotin) [25, 26, 28, 49]....
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TL;DR: The possibility that the limited retinal pigment epithelial proliferation and latent wound repair in older age-related macular degeneration patients can be stimulated to promote disease regression in age- related macularity degeneration is discussed.
Abstract: The human retinal pigment epithelium forms early in development and subsequently remains dormant, undergoing minimal proliferation throughout normal life. Retinal pigment epithelium proliferation, ...
56 citations
Cites background from "Phenotypic Plasticity of Retinal Pi..."
...Understanding the role of soluble factors, cell–cell and cell–substrate contact in regulating the balance between regenerating RPE progeny and EMT is an area of intensive research.(12,13,19) The progeny produced when RPESCs undergo EMT closely resemble the cells found in surgically excised PVR membranes which are the major cause of retinal detachment repair surgery failure....
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TL;DR: In the review, data is presented on cells serving as endogenous sources for eye tissue regeneration in lower and higher vertebrates and properties of gene expression that allow these cells to maintain their juvenile phenotype and molecular factors and conditions for induction of reprogramming and proliferation of cellular sources involved in regeneration in vitro are analyzed.
Abstract: Modern achievements in the understanding of tissue regeneration, identification of endogenous cell sources for regeneration, and development of approaches for induction and differentiation of pluripotent stem cells have open broad prospects for regenerative medicine. However, application of the obtained information in medicine is hindered by insufficient knowledge on the molecular factors and their combinations capable of regulating the age and fate of cellular sources for eye tissue reparation as well as on the regenerative responses of these cells. In the review, we present our own and literature data on cells serving as endogenous sources for eye tissue regeneration in lower and higher vertebrates and properties of gene expression that allow these cells to maintain their juvenile phenotype. Transcription factors and signal pathways providing cell juvenile status as well as cell reprogramming and entry into the S-phase are discussed. The role of systemic factors (blood and immune system factors, hormones, oxidative stress products, and cell rejuvenation factors) in these processes and their interaction with local factors of the cell environment are described. Molecular factors and conditions for induction of reprogramming and proliferation of cellular sources involved in regeneration in vitro are analyzed with special attention to the role of epigenetic factors (associated with cell senescence, in particular) in the source cells conversion during eye tissue regeneration.
11 citations
TL;DR: Immunocytochemical analysis showed that in the presence of bFGF, some cells retained epithelial properties and showed positive staining for connexin-43, while others had long axon-like processes and demonstrated positiveStaining for βIII-tubulin, which attests to their neuronal transdifferentiation.
Abstract: We studied the effect of bFGF on human retinal pigment epithelial cells in vitro In ARPE-19 cells, enhanced expression of KLF4 mRNA and reduced expression of PAX6, MITF, and OTX2 mRNA specific for retinal pigment epithelium were observed after bFGF application. The expression of KLF4 mRNA peaked in 72 h after bFGF application and then sharply decreased, which was accompanied by a 3-fold increase in TUBB3 mRNA expression (neuronal marker). Immunocytochemical analysis showed that in the presence of bFGF, some cells retained epithelial properties and showed positive staining for connexin-43, while others had long axon-like processes and demonstrated positive staining for βIII-tubulin, which attests to their neuronal transdifferentiation. Despite the prevalence of the epithelial properties, ARPE-19 cells under the influence of bFGF can show proneuronal properties.
11 citations
TL;DR: Accumulated data is considered on the relationship between the progenitor properties of RRCSs and the features determining their differentiation to find experimental approaches to replacing dead cells through recruiting cells from endogenous resources in vertebrates and humans.
Abstract: Retinal diseases often cause the loss of photoreceptor cells and, consequently, impairment of vision. To date, several cell populations are known as potential endogenous retinal regeneration cell sources (RRCSs): the eye ciliary zone, the retinal pigment epithelium, the iris, and Muller glia. Factors that can activate the regenerative responses of RRCSs are currently under investigation. The present review considers accumulated data on the relationship between the progenitor properties of RRCSs and the features determining their differentiation. Specialized RRCSs (all except the ciliary zone in low vertebrates), despite their differences, appear to be partially "prepared" to exhibit their plasticity and be reprogrammed into retinal neurons due to the specific gene expression and epigenetic landscape. The "developmental" characteristics of RRCS gene expression are predefined by the pathway by which these cell populations form during eye morphogenesis; the epigenetic features responsible for chromatin organization in RRCSs are under intracellular regulation. Such genetic and epigenetic readiness is manifested in vivo in lower vertebrates and in vitro in higher ones under conditions permissive for cell phenotype transformation. Current studies on gene expression in RRCSs and changes in their epigenetic landscape help find experimental approaches to replacing dead cells through recruiting cells from endogenous resources in vertebrates and humans.
11 citations
References
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TL;DR: This review summarizes the current knowledge of RPE functions and describes how failure of these functions causes loss of visual function.
Abstract: Located between vessels of the choriocapillaris and light-sensitive outer segments of the photoreceptors, the retinal pigment epithelium (RPE) closely interacts with photoreceptors in the maintenance of visual function. Increasing knowledge of the multiple functions performed by the RPE improved the understanding of many diseases leading to blindness. This review summarizes the current knowledge of RPE functions and describes how failure of these functions causes loss of visual function. Mutations in genes that are expressed in the RPE can lead to photoreceptor degeneration. On the other hand, mutations in genes expressed in photoreceptors can lead to degenerations of the RPE. Thus both tissues can be regarded as a functional unit where both interacting partners depend on each other.
2,387 citations
TL;DR: It is demonstrated that Pax6 directly controls the transcriptional activation of Retinogenic bHLH factors that bias subsets of RPCs toward the different retinal cell fates, thereby mediating the full retinogenic potential of RPC's.
873 citations
TL;DR: The transplanted dissociated human retinal sphere cells, containing both stem cells and progenitors, into the eyes of postnatal day 1 NOD/SCID mice and embryonic chick eyes were able to survive, migrate, integrate, and differentiate into the neural retina, especially as photoreceptors.
Abstract: This study identifies and characterizes retinal stem cells (RSCs) in early postnatal to seventh-decade human eyes. Different subregions of human eyes were dissociated and cultured by using a clonal sphere-forming assay. The stem cells were derived only from the pars plicata and pars plana of the retinal ciliary margin, at a frequency of ≈1:500. To test for long-term self-renewal, both the sphere assay and monolayer passaging were used. By using the single sphere passaging assay, primary spheres were dissociated and replated, and individual spheres demonstrated 100% self-renewal, with single spheres giving rise to one or more new spheres in each subsequent passage. The clonal retinal spheres were plated under differentiation conditions to assay the differentiation potential of their progeny. The spheres were produced all of the different retinal cell types, demonstrating multipotentiality. Therefore, the human eye contains a small population of cells (≈10,000 cells per eye) that have retinal stem-cell characteristics (proliferation, self-renewal, and multipotentiality). To test the in vivo potential of the stem cells and their progeny, we transplanted dissociated human retinal sphere cells, containing both stem cells and progenitors, into the eyes of postnatal day 1 NOD/SCID mice and embryonic chick eyes. The progeny of the RSCs were able to survive, migrate, integrate, and differentiate into the neural retina, especially as photoreceptors. Their facile isolation, integration, and differentiation suggest that human RSCs eventually may be valuable in treating human retinal diseases.
404 citations
TL;DR: The role of Pax6 in embryonic and postnatal neurogenesis, namely, production of new neurons from neural stem/progenitor cells, is focused on, because Pax6 is intensely expressed in these cells from the initial stage of CNS development and in neurogenic niches throughout life.
Abstract: Pax6 is a highly conserved transcription factor among vertebrates and is important in various developmental processes in the central nervous system (CNS), including patterning of the neural tube, migration of neurons, and formation of neural circuits. In this review, we focus on the role of Pax6 in embryonic and postnatal neurogenesis, namely, production of new neurons from neural stem/progenitor cells, because Pax6 is intensely expressed in these cells from the initial stage of CNS development and in neurogenic niches (the subgranular zone of the hippocampal dentate gyrus and the subventricular zone of the lateral ventricle) throughout life. Pax6 is a multifunctional player regulating proliferation and differentiation through the control of expression of different downstream molecules in a highly context-dependent manner.
320 citations
TL;DR: Many recent findings are outlined that suggest that a limited number of transcription factors, including Otx2, Mitf and Pax6 and a few signalling cascades, are the elements required for the onset of RPE specification in vertebrates.
Abstract: The retina pigment epithelium (RPE) is a highly specialised epithelium that serves as a multifunctional and indispensable component of the vertebrate eye. Although a great deal of attention has been paid to its transdifferentiation capabilities and its ancillary functions in neural retina development, little is known about the molecular mechanisms that specify the RPE itself. Recent advances in our understanding of the genetic network that controls the progressive specification of the eye anlage in vertebrates have provided some of the initial cues to the mechanisms responsible for RPE patterning. Here, we have outlined many recent findings that suggest that a limited number of transcription factors, including Otx2, Mitf and Pax6 and a few signalling cascades, are the elements required for the onset of RPE specification in vertebrates. Furthermore, using this information and the data available on the specification of the pigmented cells of primitive chordates, we have ventured some hypotheses on the origin of RPE cells during evolution.
267 citations