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Grigoryan EN, Markitantova YV. Molecular Strategies for Transdifferentiation of Retinal Pigment Epithelial Cells in Amphibians and Mammals In Vivo. Russ J Dev Biol 2021. [DOI: 10.1134/s1062360421040032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Kim U, Kwon M, Jung G, Kim Y, Lee Y, Im S, Cense B, Lee H, Ohm WS, Joo C. Optical dosimeter for selective retinal therapy based on multi-port fiber-optic interferometry. BIOMEDICAL OPTICS EXPRESS 2021; 12:4920-4933. [PMID: 34513233 PMCID: PMC8407823 DOI: 10.1364/boe.434812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 07/07/2021] [Indexed: 06/13/2023]
Abstract
Selective retinal therapy (SRT) employs a micro-second short-pulse lasers to induce localized destruction of the targeted retinal structures with a pulse duration and power aimed at minimal damage to other healthy retinal cells. SRT has demonstrated a great promise in the treatment of retinal diseases, but pulse energy thresholds for effective SRT procedures should be determined precisely and in real time, as the thresholds could vary with disease status and patients. In this study, we present the use of a multi-port fiber-based interferometer (MFI) for highly sensitive real-time SRT monitoring. We exploit distinct phase differences among the fiber ports in the MFI to quantitatively measure localized fluctuations of complex-valued information during the SRT procedure. We evaluate several metrics that can be computed from the full complex-valued information and demonstrate that the complex contour integration is highly sensitive and most correlative to pulse energies, acoustic outputs, and cell deaths. The validity of our method was demonstrated on excised porcine retinas, with a sensitivity and specificity of 0.92 and 0.88, respectively, as compared with the results from a cell viability assay.
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Affiliation(s)
- Uihan Kim
- Department of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea
- These authors contributed equally to this work
| | - Minsung Kwon
- Department of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea
- These authors contributed equally to this work
| | - Gyeongyeon Jung
- Department of Research, Lutronic Corporation, 219 Sowon-ro, Goyang, 10534, Republic of Korea
| | - Youngnam Kim
- Department of Research, Lutronic Corporation, 219 Sowon-ro, Goyang, 10534, Republic of Korea
| | - Yunam Lee
- Department of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea
| | - Seonghun Im
- Department of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea
| | - Barry Cense
- Department of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea
- Optical and Biomedical Engineering Laboratory, Department of Electrical, Electronic & Computer Engineering, The University of Western Australia, Perth, WA 6009, Australia
| | - Hyungsuk Lee
- Department of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea
| | - Won-Suk Ohm
- Department of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea
| | - Chulmin Joo
- Department of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea
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Progression from Type 2 Macular Neovascularization to Fibrovascular Pigment Epithelial Detachment. Vision (Basel) 2021; 5:vision5020016. [PMID: 33805868 PMCID: PMC8103250 DOI: 10.3390/vision5020016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 03/14/2021] [Accepted: 03/16/2021] [Indexed: 01/18/2023] Open
Abstract
The aim of this study was to report unusual progression of type 2 macular neovascularization (MNV) associated with age-related macular degeneration (AMD), high myopia or angioid streaks. Retrospective multicentric observational case series data were used. Eyes that progressed from type 2 MNV secondary to AMD, high myopia or angioid streaks to fibrovascular pigment epithelial detachment (PED) were included. A total of 29 treatment-naive eyes from 29 patients with type 2 MNV secondary to AMD (n = 14), high myopia (n = 10) or angioid streaks (n = 5) that progressed to a fibrovascular PED on Spectral Domain-Optical Coherence Tomography were used. This progression occurred within 3 months after anti-VEGF therapy initiation. Logarithm of minimum angle of resolution (LogMAR) visual acuity improved significantly after anti-VEGF therapy, from 0.55 (SD ± 0.30) (20/63–20/80) at baseline to 0.30 (20/40) at 3 months, and 0.33 (20/40) at the final follow-up (mean follow up: 3.68 years). Mean number of intravitreal injections per year for patients with a total follow-up ≥ 12 months (n = 24) was 4.3 ± 2.1 per year. Progression from type 2 MNV to a fibrovascular PED may occur in patients suffering from AMD, high myopia or angioid streaks. This progression appears early after initiation of anti-VEGF therapy and is associated with a favorable visual and anatomical outcome, at least on a short follow up basis.
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Grigoryan EN. Study of Natural Longlife Juvenility and Tissue Regeneration in Caudate Amphibians and Potential Application of Resulting Data in Biomedicine. J Dev Biol 2021; 9:2. [PMID: 33477527 PMCID: PMC7838874 DOI: 10.3390/jdb9010002] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 01/07/2021] [Accepted: 01/12/2021] [Indexed: 12/14/2022] Open
Abstract
The review considers the molecular, cellular, organismal, and ontogenetic properties of Urodela that exhibit the highest regenerative abilities among tetrapods. The genome specifics and the expression of genes associated with cell plasticity are analyzed. The simplification of tissue structure is shown using the examples of the sensory retina and brain in mature Urodela. Cells of these and some other tissues are ready to initiate proliferation and manifest the plasticity of their phenotype as well as the correct integration into the pre-existing or de novo forming tissue structure. Without excluding other factors that determine regeneration, the pedomorphosis and juvenile properties, identified on different levels of Urodele amphibians, are assumed to be the main explanation for their high regenerative abilities. These properties, being fundamental for tissue regeneration, have been lost by amniotes. Experiments aimed at mammalian cell rejuvenation currently use various approaches. They include, in particular, methods that use secretomes from regenerating tissues of caudate amphibians and fish for inducing regenerative responses of cells. Such an approach, along with those developed on the basis of knowledge about the molecular and genetic nature and age dependence of regeneration, may become one more step in the development of regenerative medicine.
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Affiliation(s)
- Eleonora N Grigoryan
- Kol'tsov Institute of Developmental Biology, Russian Academy of Sciences, 119334 Moscow, Russia
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Bonilha VL, Bell BA, Hu J, Milliner C, Pauer GJ, Hagstrom SA, Radu RA, Hollyfield JG. Geographic Atrophy: Confocal Scanning Laser Ophthalmoscopy, Histology, and Inflammation in the Region of Expanding Lesions. Invest Ophthalmol Vis Sci 2021; 61:15. [PMID: 32658960 PMCID: PMC7425718 DOI: 10.1167/iovs.61.8.15] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Purpose To describe the pathology of AMD in eyes with geographic atrophy (GA) using confocal scanning laser ophthalmoscopy (SLO) blue light autofluorescence (BAF), and near-infrared (IR) AF and to correlate it with the histology and immunohistochemistry analysis at the margins of the GA lesion. Methods Enucleated, fixed eyes from seventeen donors with GA were imaged and analyzed by BAF-SLO, IRAF-SLO, and by fundus macroscopy (FM). Tissue from the margins of the GA lesions was cut and processed for resin embedding and histology or cryosectioning and fluorescence in the green and far-red channels, and immunohistochemistry to assess markers of inflammation. Isolated DNA from donors was genotyped for single nucleotide polymorphisms (SNPs) previously shown to be risk factors for the development and progression of AMD. Results Around the leading edge of the GA lesions we observed hypertrophic RPE cells with cytoplasm filled with granules fluorescent both in the far-red and green-red channels; abundant microglia and macrophage; deposition of complement factor H (CFH) in Bruch's membrane (BM) and increased membrane attack complex (MAC) on RPE cells. Conclusions Fluorescence imaging of cryosections of RPE cells around the leading edge of the GA lesions suggest that IRAF-SLO visualizes mostly melanin-related compounds. In addition, medium-size GA atrophy displayed the most significant changes in inflammation markers.
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Sun WR, Ramirez S, Spiller KE, Zhao Y, Fuhrmann S. Nf2 fine-tunes proliferation and tissue alignment during closure of the optic fissure in the embryonic mouse eye. Hum Mol Genet 2020; 29:3373-3387. [PMID: 33075808 DOI: 10.1093/hmg/ddaa228] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/29/2020] [Accepted: 10/12/2020] [Indexed: 11/14/2022] Open
Abstract
Uveal coloboma represents one of the most common congenital ocular malformations accounting for up to 10% of childhood blindness (~1 in 5000 live birth). Coloboma originates from defective fusion of the optic fissure (OF), a transient gap that forms during eye morphogenesis by asymmetric, ventral invagination. Genetic heterogeneity combined with the activity of developmentally regulated genes suggests multiple mechanisms regulating OF closure. The tumor suppressor and FERM domain protein Neurofibromin 2 (NF2) controls diverse processes in cancer, development and regeneration, via Hippo pathway and cytoskeleton regulation. In humans, NF2 mutations can cause ocular abnormalities, including coloboma, however, its actual role in OF closure is unknown. Using conditional inactivation in the embryonic mouse eye, our data indicate that loss of Nf2 function results in a novel underlying cause for coloboma. In particular, mutant eyes show substantially increased retinal pigmented epithelium (RPE) proliferation in the fissure region with concomitant acquisition of RPE cell fate. Cells lining the OF margin can maintain RPE fate ectopically and fail to transition from neuroepithelial to cuboidal shape. In the dorsal RPE of the optic cup, Nf2 inactivation leads to a robust increase in cell number, with local disorganization of the cytoskeleton components F-actin and pMLC2. We propose that RPE hyperproliferation is the primary cause for the observed defects causing insufficient alignment of the OF margins in Nf2 mutants and failure to fuse properly, resulting in persistent coloboma. Our findings indicate that limiting proliferation particularly in the RPE layer is a critical mechanism during OF closure.
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Affiliation(s)
- Wesley R Sun
- Department of Ophthalmology and Visual Sciences, VEI, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Sara Ramirez
- Department of Ophthalmology and Visual Sciences, VEI, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
| | - Kelly E Spiller
- Department of Ophthalmology and Visual Sciences, VEI, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Yan Zhao
- Department of Ophthalmology and Visual Sciences, VEI, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Sabine Fuhrmann
- Department of Ophthalmology and Visual Sciences, VEI, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
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Grigoryan EN. Potential Endogenous Cell Sources for Retinal Regeneration in Vertebrates and Humans: Progenitor Traits and Specialization. Biomedicines 2020; 8:E208. [PMID: 32664635 PMCID: PMC7400588 DOI: 10.3390/biomedicines8070208] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 07/04/2020] [Accepted: 07/10/2020] [Indexed: 12/11/2022] Open
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 Müller 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.
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Affiliation(s)
- Eleonora N Grigoryan
- Koltsov Institute of Developmental Biology, Russian Academy of Sciences, 119334 Moscow, Russia
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Grigoryan EN, Radugina EA. Behavior of Stem-Like Cells, Precursors for Tissue Regeneration in Urodela, Under Conditions of Microgravity. Stem Cells Dev 2019; 28:423-437. [PMID: 30696352 DOI: 10.1089/scd.2018.0220] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
We summarize data from our experiments on stem-like cell-dependent regeneration in amphibians in microgravity. Considering its deleterious effect on many tissues, we asked whether microgravity is compatible with reparative processes, specifically activation and proliferation of source cells. Experiments were conducted using tailed amphibians, which combine profound regenerative capabilities with high robustness, allowing an in vivo study of lens, retina, limb, and tail regeneration in challenging settings of spaceflight. Microgravity promoted stem-like cell proliferation to a varying extent (up to 2-fold), and it seemed to speed up source cell dedifferentiation, as well as sequential differentiation in retina, lens, and limb, leading to formation of bigger and more developed regenerates than in 1g controls. It also promoted proliferation and hypertrophy of Müller glial cells, eliciting a response similar to reactive gliosis. A significant increase in stem-like cell proliferation was mostly beneficial for regeneration and only in rare cases caused moderate tissue growth abnormalities. It is important that microgravity yielded a lasting effect even if applied before operations. We hypothesize on the potential mechanisms of gravity-dependent changes in stem-like cell behavior, including fibroblast growth factor 2 signaling pathway and heat shock proteins, which were affected in our experimental settings. Taken together, our data indicate that microgravity does not disturb the natural regenerative potential of newt stem-like cells, and, depending on the system, even stimulates their dedifferentiation, proliferation, and differentiation. We discuss these data along with publications on mammalian stem cell behavior in vitro and invertebrate regeneration in vivo in microgravity. In vivo data are very scarce and require further research using contemporary methods of cell behavior analysis to elucidate mechanisms of stem cell response to altered gravity. They are relevant for both practical applications, such as managing human reparative responses in spaceflight, and fundamental understanding of stem cell biology.
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Affiliation(s)
- Eleonora N Grigoryan
- Koltzov Institute of Developmental Biology of Russian Academy of Sciences, Moscow, Russia
| | - Elena A Radugina
- Koltzov Institute of Developmental Biology of Russian Academy of Sciences, Moscow, Russia
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Grigoryan EN. Endogenous Cell Sources for Eye Retina Regeneration in Vertebrate Animals and Humans. Russ J Dev Biol 2019. [DOI: 10.1134/s106236041901003x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Grigoryan EN. Molecular Factors of the Maintenance and Activation of the Juvenile Phenotype of Cellular Sources for Eye Tissue Regeneration. BIOCHEMISTRY (MOSCOW) 2018; 83:1318-1331. [DOI: 10.1134/s0006297918110032] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Mohd Lazaldin MA, Iezhitsa I, Agarwal R, Bakar NS, Agarwal P, Mohd Ismail N. Time- and dose-related effects of amyloid beta1-40 on retina and optic nerve morphology in rats. Int J Neurosci 2018; 128:952-965. [PMID: 29488424 DOI: 10.1080/00207454.2018.1446953] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
PURPOSE Amyloid beta (Aβ) is known to contribute to the pathophysiology of retinal neurodegenerative diseases such as glaucoma. Effects of intravitreal Aβ(1-42) on retinal and optic nerve morphology in animal models have widely been studied but not those of Aβ(1-40). Hence, we evaluated the time- and dose-related effects of intravitreal Aβ(1-40) on retinal and optic nerve morphology. Since oxidative stress and brain derived neurotrophic factor (BDNF) are associated with Aβ-induced neuronal damage, we also studied dose and time-related effects of Aβ(1-40) on retinal oxidative stress and BDNF levels. MATERIALS AND METHODS Five groups of rats were intravitreally administered with vehicle or Aβ(1-40) in doses of 1.0, 2.5, 5 and 10 nmol. Animals were sacrificed and eyes were enucleated at weeks 1, 2 and 4 post-injection. The retinae were subjected to morphometric analysis and TUNEL staining. Optic nerve sections were stained with toluidine blue and were graded for neurodegenerative effects. The estimation of BDNF and markers of oxidative stress in retina were done using ELISA technique. RESULTS AND CONCLUSIONS It was observed that intravitreal Aβ(1-40) causes significant retinal and optic nerve damage up to day 14 post-injection and there was increasing damage with increase in dose. However, on day 30 post-injection both the retinal and optic nerve morphology showed a trend towards normalization. The observations made for retinal cell apoptosis, retinal glutathione, superoxide dismutase activity and BDNF were in accordance with those of morphological changes with deterioration till day 14 and recovery by day 30 post-injection. The findings of this study may provide a guide for selection of appropriate experimental conditions for future studies.
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Affiliation(s)
- Mohd Aizuddin Mohd Lazaldin
- a Centre For Neuroscience Research, Faculty of Medicine , Universiti Teknologi MARA, Sungai Buloh Campus, Selangor , Malaysia
| | - Igor Iezhitsa
- a Centre For Neuroscience Research, Faculty of Medicine , Universiti Teknologi MARA, Sungai Buloh Campus, Selangor , Malaysia.,b Research Institute of Pharmacology, Volgograd State Medical University , Volgograd , Russia
| | - Renu Agarwal
- a Centre For Neuroscience Research, Faculty of Medicine , Universiti Teknologi MARA, Sungai Buloh Campus, Selangor , Malaysia
| | - Nor Salmah Bakar
- a Centre For Neuroscience Research, Faculty of Medicine , Universiti Teknologi MARA, Sungai Buloh Campus, Selangor , Malaysia
| | - Puneet Agarwal
- c IMU Clinical School, International Medical University , Seremban , Malaysia
| | - Nafeeza Mohd Ismail
- a Centre For Neuroscience Research, Faculty of Medicine , Universiti Teknologi MARA, Sungai Buloh Campus, Selangor , Malaysia
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Vrolyk V, Haruna J, Benoit-Biancamano MO. Neonatal and Juvenile Ocular Development in Sprague-Dawley Rats: A Histomorphological and Immunohistochemical Study. Vet Pathol 2017; 55:310-330. [DOI: 10.1177/0300985817738098] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
As in many altricial species, rats are born with fused eyelids and markedly underdeveloped eyes. While the normal histology of the eyes of mature rats is known, the histomorphological changes occurring during postnatal eye development in this species remain incompletely characterized. This study was conducted to describe the postnatal development of ocular structures in Sprague-Dawley (SD) rats during the first month of age using histology and immunohistochemistry (IHC). Both eyes were collected from 51 SD rats at 13 time points between postnatal day (PND)1 and PND30. Histologic examination of hematoxylin and eosin-stained sections was performed, as well as IHC for cleaved-caspase-3 and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) to evaluate apoptosis, and IHC for Ki-67 and phospho-histone-H3 to evaluate cell proliferation. Extensive ocular tissue remodeling occurred prior to the eyelid opening around PND14 and reflected the interplay between apoptosis and cell proliferation. Apoptosis was particularly remarkable in the maturing subcapsular anterior epithelium of the lens, the inner nuclear and ganglion cell layers of the developing retina, and the Harderian gland, and was involved in the regression of the hyaloid vasculature. Nuclear degradation in the newly formed secondary lens fibers was noteworthy after birth and was associated with TUNEL-positive nuclear remnants lining the lens organelle-free zone. Cell proliferation was marked in the developing retina, cornea, iris, ciliary body and Harderian gland. The rat eye reached histomorphological maturity at PND21 after a rapid phase of morphological changes characterized by the coexistence of cell death and proliferation.
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Affiliation(s)
- Vanessa Vrolyk
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC, Canada
| | | | - Marie-Odile Benoit-Biancamano
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC, Canada
- Groupe de recherche en pharmacologie animale du Québec (GREPAQ), Faculty of Veterinary Medicne University of Montreal, Saint-Hyacinthe, QC, Canada
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Telegina DV, Kozhevnikova OS, Bayborodin SI, Kolosova NG. Contributions of age-related alterations of the retinal pigment epithelium and of glia to the AMD-like pathology in OXYS rats. Sci Rep 2017; 7:41533. [PMID: 28134357 PMCID: PMC5278403 DOI: 10.1038/srep41533] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 12/20/2016] [Indexed: 11/09/2022] Open
Abstract
Age-related macular degeneration (AMD) is a major cause of blindness in developed countries, and the molecular pathogenesis of early events of AMD is poorly understood. It is known that age-related alterations of retinal pigment epithelium (RPE) cells and of glial reactivity are early hallmarks of AMD. Here we evaluated contributions of the age-related alterations of the RPE and of glia to the development of AMD-like retinopathy in OXYS rats. We showed that destructive alterations in RPE cells are a primary change during the development of retinopathy in OXYS rats. Furthermore, a defect of retinal maturation and decreased immune function at the preclinical stage of retinopathy were observed in OXYS rats in addition to the impairment of RPE cell proliferation and of their capacity for division. At the active stage of the disease, the atrophic alterations increased, and reactive gliosis was observed when disease progressed, but immune function stayed weakened. Unexpectedly, we did not observe migration of microglia and macrophages into the photoreceptor layer. These results and the wide spectrum of age-related retinal alterations in humans as well as individual differences in the risk of AMD may be attributed to genetic factors and to differences in the underlying molecular events.
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Affiliation(s)
- Darya V Telegina
- Institute of Cytology and Genetics SB RAS, Novosibirsk 630090, Russia
| | | | | | - Nataliya G Kolosova
- Institute of Cytology and Genetics SB RAS, Novosibirsk 630090, Russia.,Novosibirsk State University, Novosibirsk 630090, Russia
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Grigoryan EN, Markitantova YV. Cellular and Molecular Preconditions for Retinal Pigment Epithelium (RPE) Natural Reprogramming during Retinal Regeneration in Urodela. Biomedicines 2016; 4:E28. [PMID: 28536395 PMCID: PMC5344269 DOI: 10.3390/biomedicines4040028] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 11/26/2016] [Accepted: 11/26/2016] [Indexed: 12/25/2022] Open
Abstract
Many regeneration processes in animals are based on the phenomenon of cell reprogramming followed by proliferation and differentiation in a different specialization direction. An insight into what makes natural (in vivo) cell reprogramming possible can help to solve a number of biomedical problems. In particular, the first problem is to reveal the intrinsic properties of the cells that are necessary and sufficient for reprogramming; the second, to evaluate these properties and, on this basis, to reveal potential endogenous sources for cell substitution in damaged tissues; and the third, to use the acquired data for developing approaches to in vitro cell reprogramming in order to obtain a cell reserve for damaged tissue repair. Normal cells of the retinal pigment epithelium (RPE) in newts (Urodela) can change their specialization and transform into retinal neurons and ganglion cells (i.e., actualize their retinogenic potential). Therefore, they can serve as a model that provides the possibility to identify factors of the initial competence of vertebrate cells for reprogramming in vivo. This review deals mainly with the endogenous properties of native newt RPE cells themselves and, to a lesser extent, with exogenous mechanisms regulating the process of reprogramming, which are actively discussed.
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Affiliation(s)
- Eleonora N Grigoryan
- Kol'tsov Institute of Developmental Biology, Russian Academy of Sciences, Moscow 119334, Russia.
| | - Yuliya V Markitantova
- Kol'tsov Institute of Developmental Biology, Russian Academy of Sciences, Moscow 119334, Russia.
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15
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Grigoryan EN. High regenerative ability of tailed amphibians (Urodela) as a result of the expression of juvenile traits by mature animals. Russ J Dev Biol 2016. [DOI: 10.1134/s1062360416020041] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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16
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Zakhidov ST, Marshak TL. Experimental evidence of proliferation and reproduction of highly differentiated Sertoli cells. BIOL BULL+ 2015. [DOI: 10.1134/s1062359015040159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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17
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Abstract
The human retinal pigment epithelium forms early in development and subsequently remains dormant, undergoing minimal proliferation throughout normal life. Retinal pigment epithelium proliferation, however, can be activated in disease states or by removing retinal pigment epithelial cells into culture. We review the conditions that control retinal pigment epithelial proliferation in culture, in animal models and in human disease and interpret retinal pigment epithelium proliferation in context of the recently discovered retinal pigment epithelium stem cell that is responsible for most in vitro retinal pigment epithelial proliferation. Retinal pigment epithelial proliferation-mediated wound repair that occurs in selected macular diseases is contrasted with retinal pigment epithelial proliferation-mediated fibroblastic scar formation that underlies proliferative vitreoretinopathy. We discuss the role of retinal pigment epithelial proliferation in age-related macular degeneration which is reparative in some cases and destructive in others. Macular retinal pigment epithelium wound repair and regression of choroidal neovascularization are more pronounced in younger than older patients. We discuss 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 macular degeneration.
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Affiliation(s)
- Jeffrey Stern
- Neural Stem Cell Institute, One Discovery Drive, Rensselaer, New York 12144, USA Capital Region Retina, PLLC, Washington Avenue, Albany, New York 12206, USA
| | - Sally Temple
- Neural Stem Cell Institute, One Discovery Drive, Rensselaer, New York 12144, USA
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Jayakody SA, Gonzalez-Cordero A, Ali RR, Pearson RA. Cellular strategies for retinal repair by photoreceptor replacement. Prog Retin Eye Res 2015; 46:31-66. [PMID: 25660226 DOI: 10.1016/j.preteyeres.2015.01.003] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 01/13/2015] [Accepted: 01/19/2015] [Indexed: 02/08/2023]
Abstract
Loss of photoreceptors due to retinal degeneration is a major cause of blindness in the developed world. While no effective treatment is currently available, cell replacement therapy, using pluripotent stem cell-derived photoreceptor precursor cells, may be a feasible future treatment. Recent reports have demonstrated rescue of visual function following the transplantation of immature photoreceptors and we have seen major advances in our ability to generate transplantation-competent donor cells from stem cell sources. Moreover, we are beginning to realise the possibilities of using endogenous populations of cells from within the retina itself to mediate retinal repair. Here, we present a review of our current understanding of endogenous repair mechanisms together with recent progress in the use of both ocular and pluripotent stem cells for the treatment of photoreceptor loss. We consider how our understanding of retinal development has underpinned many of the recent major advances in translation and moved us closer to the goal of restoring vision by cellular means.
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Affiliation(s)
- Sujatha A Jayakody
- Gene and Cell Therapy Group, Department of Genetics, UCL Institute of Ophthalmology, 11-43 Bath St, London EC1V 9EL, UK
| | - Anai Gonzalez-Cordero
- Gene and Cell Therapy Group, Department of Genetics, UCL Institute of Ophthalmology, 11-43 Bath St, London EC1V 9EL, UK
| | - Robin R Ali
- Gene and Cell Therapy Group, Department of Genetics, UCL Institute of Ophthalmology, 11-43 Bath St, London EC1V 9EL, UK; NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, City Road, London EC1V 2PD, UK
| | - Rachael A Pearson
- Gene and Cell Therapy Group, Department of Genetics, UCL Institute of Ophthalmology, 11-43 Bath St, London EC1V 9EL, UK.
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Grigoryan EN. Competence factors of retinal pigment epithelium cells for reprogramming in the neuronal direction during retinal regeneration in newts. BIOL BULL+ 2015. [DOI: 10.1134/s1062359015010045] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Wolkow N, Li Y, Maminishkis A, Song Y, Alekseev O, Iacovelli J, Song D, Lee JC, Dunaief JL. Iron upregulates melanogenesis in cultured retinal pigment epithelial cells. Exp Eye Res 2014; 128:92-101. [PMID: 25277027 DOI: 10.1016/j.exer.2014.09.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 09/12/2014] [Accepted: 09/26/2014] [Indexed: 12/20/2022]
Abstract
The purpose of our studies was to examine the relationship between iron and melanogenesis in retinal pigment epithelial cells, as prior observations had suggested that iron may promote melanogenesis. This relationship has potential clinical importance, as both iron overload and hyperpigmentation are associated with age-related macular degeneration (AMD). Human fetal retinal pigment epithelial cells and ARPE-19 cells were treated with iron in the form of ferric ammonium citrate, after which quantitative RT-PCR and electron microscopy were performed. Melanogenesis genes tyrosinase, tyrosinase-related protein 1, Hermansky-Pudlak Syndrome 3, premelanosome protein and dopachrome tautomerase were upregulated, as was the melanogenesis-controlling transcription factor, microphthalmia-associated transcription factor (MITF). Iron-treated cells had increased pigmentation and melanosome number. Multiple transcription factors upstream of MITF were upregulated by iron.
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Affiliation(s)
- Natalie Wolkow
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104, USA
| | - Yafeng Li
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104, USA
| | - Arvydas Maminishkis
- Section of Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bldg. 10, Rm. 10B04, MSC 1861, 10 Center Drive, Bethesda, MD 20892, USA
| | - Ying Song
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104, USA
| | - Oleg Alekseev
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104, USA
| | - Jared Iacovelli
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104, USA
| | - Delu Song
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104, USA
| | - Jennifer C Lee
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104, USA
| | - Joshua L Dunaief
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104, USA.
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Kuznetsova AV, Kurinov AM, Aleksandrova MA. Cell models to study regulation of cell transformation in pathologies of retinal pigment epithelium. J Ophthalmol 2014; 2014:801787. [PMID: 25177495 PMCID: PMC4142280 DOI: 10.1155/2014/801787] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 06/16/2014] [Accepted: 06/30/2014] [Indexed: 11/25/2022] Open
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.
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Affiliation(s)
- Alla V. Kuznetsova
- N.K. Koltsov Institute of Developmental Biology, Russian Academy of Sciences, ul. Vavilova 26, Moscow 119334, Russia
| | - Alexander M. Kurinov
- N.K. Koltsov Institute of Developmental Biology, Russian Academy of Sciences, ul. Vavilova 26, Moscow 119334, Russia
| | - Maria A. Aleksandrova
- N.K. Koltsov Institute of Developmental Biology, Russian Academy of Sciences, ul. Vavilova 26, Moscow 119334, Russia
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Hidalgo M, Locker M, Chesneau A, Perron M. Stem Cells and Regeneration in the Xenopus Retina. STEM CELL BIOLOGY AND REGENERATIVE MEDICINE 2014. [DOI: 10.1007/978-1-4939-0787-8_4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Fuhrmann S, Zou C, Levine EM. Retinal pigment epithelium development, plasticity, and tissue homeostasis. Exp Eye Res 2013; 123:141-50. [PMID: 24060344 DOI: 10.1016/j.exer.2013.09.003] [Citation(s) in RCA: 171] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 09/05/2013] [Accepted: 09/07/2013] [Indexed: 12/13/2022]
Abstract
The retinal pigment epithelium (RPE) is a simple epithelium interposed between the neural retina and the choroid. Although only 1 cell-layer in thickness, the RPE is a virtual workhorse, acting in several capacities that are essential for visual function and preserving the structural and physiological integrities of neighboring tissues. Defects in RPE function, whether through chronic dysfunction or age-related decline, are associated with retinal degenerative diseases including age-related macular degeneration. As such, investigations are focused on developing techniques to replace RPE through stem cell-based methods, motivated primarily because of the seemingly limited regeneration or self-repair properties of mature RPE. Despite this, RPE cells have an unusual capacity to transdifferentiate into various cell types, with the particular fate choices being highly context-dependent. In this review, we describe recent findings elucidating the mechanisms and steps of RPE development and propose a developmental framework for understanding the apparent contradiction in the capacity for low self-repair versus high transdifferentiation.
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Affiliation(s)
- Sabine Fuhrmann
- Department of Ophthalmology & Visual Sciences, John A. Moran Eye Center, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT 84132, USA.
| | - ChangJiang Zou
- Department of Ophthalmology & Visual Sciences, John A. Moran Eye Center, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT 84132, USA.
| | - Edward M Levine
- Department of Ophthalmology & Visual Sciences, John A. Moran Eye Center, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT 84132, USA.
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Peng S, Gan G, Qiu C, Zhong M, An H, Adelman RA, Rizzolo LJ. Engineering a blood-retinal barrier with human embryonic stem cell-derived retinal pigment epithelium: transcriptome and functional analysis. Stem Cells Transl Med 2013; 2:534-44. [PMID: 23734062 DOI: 10.5966/sctm.2012-0134] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Retinal degenerations are a major cause of impaired vision in the elderly. Degenerations originate in either photoreceptors or the retinal pigment epithelium (RPE). RPE forms the outer blood-retinal barrier and functions intimately with photoreceptors. Animal models and cultures of RPE are commonly used to screen potential pharmaceuticals or explore RPE replacement therapy, but human RPE differs from that of other species. Human RPE forms a barrier using tight junctions composed of a unique set of claudins, proteins that determine the permeability and selectivity of tight junctions. Human adult RPE fails to replicate these properties in vitro. To develop a culture model for drug development and tissue-engineering human retina, RPE were derived from human embryonic stem cells (hESCs). Barrier properties of RPE derived from the H1 and H9 hESC lines were compared with a well-regarded model of RPE function, human fetal RPE isolated from 16-week-gestation fetuses (hfRPE). A serum-free medium (SFM-1) that enhanced the redifferentiation of hfRPE in culture also furthered the maturation of hESC-derived RPE. In SFM-1, the composition, selectivity, and permeability of tight junctions were similar to those of hfRPE. Comparison of the transcriptomes by RNA sequencing and quantitative reverse transcription-polymerase chain reaction revealed a high correlation between the hESCs and hfRPE, but there were notable differences in the expression of adhesion junction and membrane transport genes. These data indicated that hESC-derived RPE is highly differentiated but may be less mature than RPE isolated from 16-week fetuses. The study identified a panel of genes to monitor the maturation of RPE.
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Affiliation(s)
- Shaomin Peng
- Department of Surgery, Yale University School of Medicine, New Haven, CT, USA
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Grigoryan EN, Markitantova YV, Avdonin PP, Radugina EA. Study of regeneration in amphibians in age of molecular-genetic approaches and methods. RUSS J GENET+ 2013. [DOI: 10.1134/s1022795413010043] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Phenotypic plasticity of retinal pigment epithelial cells from adult human eye in vitro. Bull Exp Biol Med 2012; 151:506-11. [PMID: 22448378 DOI: 10.1007/s10517-011-1368-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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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Hematological- and Neurological-Expressed Sequence 1 Gene Products in Progenitor Cells during Newt Retinal Development. Stem Cells Int 2012; 2012:436042. [PMID: 22719773 PMCID: PMC3375142 DOI: 10.1155/2012/436042] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Accepted: 04/01/2012] [Indexed: 12/16/2022] Open
Abstract
Urodele amphibians such as Japanese common newts have a remarkable ability to regenerate their injured neural retina, even as adults. We found that hematological- and neurological-expressed sequence 1 (Hn1) gene was induced in depigmented retinal pigment epithelial (RPE) cells, and its expression was maintained at later stages of newt retinal regeneration. In this study, we investigated the distribution of the HN1 protein, the product of the Hn1 gene, in the developing retinas. Our immunohistochemical analyses suggested that the HN1 protein was highly expressed in an immature retina, and the subcellular localization changed during this retinogenesis as observed in newt retinal regeneration. We also found that the expression of Hn1 gene was not induced in mouse after retinal removal. Our results showed that Hn1 gene can be useful for detection of undifferentiated and dedifferentiated cells during both newt retinal development and regeneration.
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Abstract
Cell therapy is based on the replacement of damaged cells in order to restore injured tissues. The first consideration is that an abundant source of cells is needed; second, these cells should be immunologically compatible with the guest and third, there should be no real threat of these cells undergoing malignant transformation in the future. Given these requirements, already differentiated adult cells or adult stem cells obtained from the body of the patient appear to be the ideal candidates to meet all of these demands. The utilization of somatic cells also avoids numerous ethical and political drawbacks and concerns. Transdifferentiation is the phenomenon by which an adult differentiated cell switches to another differentiated cell. This paper reviews the importance of transdifferentiation, discussing the cells that are suitable for this process and the methods currently employed to induce the change in cell type.
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Rizzolo LJ, Peng S, Luo Y, Xiao W. Integration of tight junctions and claudins with the barrier functions of the retinal pigment epithelium. Prog Retin Eye Res 2011; 30:296-323. [PMID: 21704180 DOI: 10.1016/j.preteyeres.2011.06.002] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 06/01/2011] [Accepted: 06/06/2011] [Indexed: 02/02/2023]
Abstract
The retinal pigment epithelium (RPE) forms the outer blood-retinal barrier by regulating the movement of solutes between the fenestrated capillaries of the choroid and the photoreceptor layer of the retina. Blood-tissue barriers use various mechanisms to accomplish their tasks including membrane pumps, transporters, and channels, transcytosis, metabolic alteration of solutes in transit, and passive but selective diffusion. The last category includes tight junctions, which regulate transepithelial diffusion through the spaces between neighboring cells of the monolayer. Tight junctions are extraordinarily complex structures that are dynamically regulated. Claudins are a family of tight junctional proteins that lend tissue specificity and selectivity to tight junctions. This review discusses how the claudins and tight junctions of the RPE differ from other epithelia and how its functions are modulated by the neural retina. Studies of RPE-retinal interactions during development lend insight into this modulation. Notably, the characteristics of RPE junctions, such as claudin composition, vary among species, which suggests the physiology of the outer retina may also vary. Comparative studies of barrier functions among species should deepen our understanding of how homeostasis is maintained in the outer retina. Stem cells provide a way to extend these studies of RPE-retinal interactions to human RPE.
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Affiliation(s)
- Lawrence J Rizzolo
- Department of Surgery and Department of Ophthalmology and Visual Science, Yale University School of Medicine, PO Box 208062, New Haven, CT 06520-8062, USA.
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Fischer AJ, Bongini R. Turning Müller glia into neural progenitors in the retina. Mol Neurobiol 2010; 42:199-209. [PMID: 21088932 DOI: 10.1007/s12035-010-8152-2] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 11/10/2010] [Indexed: 12/22/2022]
Abstract
Stimulating neuronal regeneration is a potential strategy to treat sight-threatening diseases of the retina. In some classes of vertebrates, retinal regeneration occurs spontaneously to effectively replace neurons lost to acute damage in order to restore visual function. There are different mechanisms and cellular sources of retinal regeneration in different species, include the retinal pigmented epithelium, progenitors seeded across the retina, and the Müller glia. This review briefly summarizes the different mechanisms of retinal regeneration in frogs, fish, chicks, and rodents. The bulk of this review summarizes and discusses recent findings regarding regeneration from Müller glia-derived progenitors, with emphasis on findings in the chick retina. The Müller glia are a promising source of regeneration-supporting cells that are intrinsic to the retina and significant evidence indicated these glias can be stimulated to produce neurons in different classes of vertebrates. The key to harnessing the neurogenic potential of Müller glia is to identify the secreted factors, signaling pathways, and transcription factors that enable de-differentiation, proliferation, and neurogenesis. We review findings regarding the roles of mitogen-activated protein kinase and notch signaling in the proliferation and generation of Müller glia-derived retinal progenitors.
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Affiliation(s)
- Andy J Fischer
- Department of Neuroscience, College of Medicine, The Ohio State University, 3020 Graves Hall, 333 West 10th Ave, Columbus, OH 43210-1239, USA.
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Novikova YP, Aleinikova KS, Poplinskaya VA, Grigoryan EN. The retinal pigment epithelial cells of the adult newt and rat under conditions of in vitro organotypic culture. BIOL BULL+ 2010. [DOI: 10.1134/s1062359010030027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Abstract
Organogenesis of the eye is a multistep process that starts with the formation of optic vesicles followed by invagination of the distal domain of the vesicles and the overlying lens placode resulting in morphogenesis of the optic cup. The late optic vesicle becomes patterned into distinct ocular tissues: the neural retina, retinal pigment epithelium (RPE), and optic stalk. Multiple congenital eye disorders, including anophthalmia or microphthalmia, aniridia, coloboma, and retinal dysplasia, stem from disruptions in embryonic eye development. Thus, it is critical to understand the mechanisms that lead to initial specification and differentiation of ocular tissues. An accumulating number of studies demonstrate that a complex interplay between inductive signals provided by tissue-tissue interactions and cell-intrinsic factors is critical to ensuring proper specification of ocular tissues as well as maintenance of RPE cell fate. While several of the extrinsic and intrinsic determinants have been identified, we are just at the beginning in understanding how these signals are integrated. In addition, we know very little about the actual output of these interactions. In this chapter, we provide an update of the mechanisms controlling the early steps of eye development in vertebrates, with emphasis on optic vesicle evagination, specification of neural retina and RPE at the optic vesicle stage, the process of invagination during morphogenesis of the optic cup, and maintenance of the RPE cell fate.
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Affiliation(s)
- Sabine Fuhrmann
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, Utah, USA
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Milyushina LA, Poltavtseva RA, Marei MV, Podgornyi OV, Sukhikh GT, Aleksandrova MA. In Vitro Phenotypic Modifi cation of Pigmented Epithelium Cells from Human Eye at Early Stages of Development. Bull Exp Biol Med 2009; 148:113-9. [DOI: 10.1007/s10517-009-0657-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Mäenpää H, Gegelashvili G, Tähti H. Expression of glutamate transporter subtypes in cultured retinal pigment epithelial and retinoblastoma cells. Curr Eye Res 2009; 28:159-65. [PMID: 14977517 DOI: 10.1076/ceyr.28.3.159.26244] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
PURPOSE Glutamate is the major excitatory neurotransmitter in the retina and glutamate uptake is essential for normal glutamate signalling. Retinal diseases may induce neurochemical changes which affect retinal cells including retinal pigment epithelium (RPE). The aim of the study was to investigate the expression of glutamate transporter subtypes in RPE and retinoblastoma cells and to clarify the effect of proliferation modulators on the levels of the expressed transporter in the RPE cell line. METHODS Cultured pig RPE cells and two human RPE cell lines, D407 and ARPE-19, as well as the human retinoblastoma cell line Y79 were used. Glutamate transporter expression was evaluated with Western blot analysis and immunocytochemistry. RESULTS The study revealed unexpected expression of neuronal glutamate transporter/chloride channel EAAT4 in these three cell lines, but not in cultured pig RPE cells, whereas another glutamate carrier, EAAC1, was present in all cell types utilized. Other transporter subtypes, GLT1, GLAST and EAAT5 were not found. Neither tamoxifen, known to inhibit both proliferation and glutamate uptake in RPE cells, nor retinoic acid nor insulin, also known to affect cell proliferation rates, were capable of changing the total levels of EAAT4 in APRE-19 cells. CONCLUSIONS Neuronal glutamate transporter EAAC1 is expressed in RPE cells. The robust expression of EAAT4 in cell lines may reflect a role of EAAT4 in cell proliferation and migration. Unaltered steady-state expression of this carrier and chloride-channel protein hints at posttranslational mechanisms of regulation of EAAT4.
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Affiliation(s)
- Hanna Mäenpää
- Cell Research Center, Medical School, University of Tampere, Tampere, Finland.
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Abstract
Over the past few years a great deal of interest has been generated in using stem cells/progenitors to treat degenerative diseases that afflict different tissues, including retina. This interest is due to the defining properties of stem cells/progenitors, the ability of these cells to self-renew and generate all the basic cell types of the particular tissue to which they belong. In addition, the recent reports of plasticity of the adult tissue-specific stem cells/progenitors and directed differentiation of the embryonic cells (ES) has fueled the hope for cell and gene therapy using stem cells from heterologous sources. Will this approach work for treating retinal degeneration? Here, we review the current state of knowledge about obtaining retinal cells from heterologous sources, including ES cells.
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Affiliation(s)
- Ani M Das
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, 68198, USA
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Elucidating the phenomenon of HESC-derived RPE: anatomy of cell genesis, expansion and retinal transplantation. Exp Neurol 2008; 214:347-61. [PMID: 18926821 DOI: 10.1016/j.expneurol.2008.09.007] [Citation(s) in RCA: 216] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2008] [Revised: 08/12/2008] [Accepted: 09/05/2008] [Indexed: 01/12/2023]
Abstract
Healthy Retinal Pigment Epithelium (RPE) cells are required for proper visual function and the phenomenon of RPE derivation from Human Embryonic Stem Cells (HESC) holds great potential for the treatment of retinal diseases. However, little is known about formation, expansion and expression profile of RPE-like cells derived from HESC (HESC-RPE). By studying the genesis of pigmented foci we identified OTX1/2-positive cell types as potential HESC-RPE precursors. When pigmented foci were excised from culture, HESC-RPE expanded to form extensive monolayers, with pigmented cells at the leading edge assuming a precursor role: de-pigmenting, proliferating, expressing keratin 8 and subsequently re-differentiating. As they expanded and differentiated in vitro, HESC-RPE expressed markers of both developing and mature RPE cells which included OTX1/2, Pax6, PMEL17 and at low levels, RPE65. In vitro, without signals from a developing retinal environment, HESC-RPE could produce regular, polarised monolayers with developmentally important apical and basal features. Following transplantation of HESC-RPE into the degenerating retinal environment of Royal College of Surgeons (RCS) dystrophic rats, the cells survived in the subretinal space, where they maintained low levels of RPE65 expression and remained out of the cell cycle. The HESC-RPE cells responded to the in vivo environment by downregulating Pax6, while maintaining expression of other markers. The presence of rhodopsin-positive material within grafted HESC-RPE indicates that in the future, homogenous transplants of this cell type may be capable of supporting visual function following retinal dystrophy.
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Avdonin PP, Markitantova YV, Zinovieva RD, Mitashov VI. Expression of regulatory genes Px6, Otx2, Six3, and FGF2 during newt retina regeneration. BIOL BULL+ 2008. [DOI: 10.1134/s1062359008040043] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Vugler A, Lawrence J, Walsh J, Carr A, Gias C, Semo M, Ahmado A, da Cruz L, Andrews P, Coffey P. Embryonic stem cells and retinal repair. Mech Dev 2007; 124:807-29. [PMID: 17881192 DOI: 10.1016/j.mod.2007.08.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Revised: 08/07/2007] [Accepted: 08/07/2007] [Indexed: 12/11/2022]
Abstract
In this review we examine the potential of embryonic stem cells (ESCs) for use in the treatment of retinal diseases involving photoreceptors and retinal pigment epithelium (RPE). We outline the ontogenesis of target retinal cell types (RPE, rods and cones) and discuss how an understanding of developmental processes can inform our manipulation of ESCs in vitro. Due to their potential for cellular therapy, special emphasis is placed upon the derivation and culture of human embryonic stem cells (HESCs) and their differentiation towards a retinal phenotype. In terms of achieving this goal, we suggest that much of the success to date reflects permissive in vitro environments provided by established protocols for HESC derivation, propagation and neural differentiation. In addition, we summarise key factors that may be important for enhancing efficiency of retinal cell-type derivation from HESCs. The retina is an amenable component of the central nervous system (CNS) and as such, diseases of this structure provide a realistic target for the application of HESC-derived cellular therapy to the CNS. In order to further this goal, the second component of our review focuses on the cellular and molecular cues within retinal environments that may influence the survival and behaviour of transplanted cells. Our analysis considers both the potential barriers to transplant integration in the retina itself together with the remodelling in host visual centres that is known to accompany retinal dystrophy.
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Affiliation(s)
- Anthony Vugler
- Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V9EL, UK.
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Abstract
During the embryonic development of the eye, a group of founder cells in the optic vesicle gives rise to multipotent progenitor cells that generate all the neurons and the Müller glia of the mature retina. In most vertebrates, a small group of retinal stem cells persists at the margin of the retina, near the junction with the ciliary epithelium. In fish and amphibians, the retinal stem cells continue to produce progenitors throughout life, adding new retina to the periphery of the existing retina as the eye grows. In birds the new retinal addition is more limited, and it is absent in those mammals that have been analyzed. Nevertheless, cells from the retinal periphery and ciliary body of mammals can be isolated and grown in vitro for extended periods. Methods for the study of both embryonic progenitors and adult retinal stem cells in vitro and in vivo have led to a better understanding of retinal development, allowed for the screening of factors important in retinal growth and differentiation, and enabled the development of methods to direct stem and progenitor cells to specific fates. These methods may ultimately lead to the development of strategies for retinal repair.
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Affiliation(s)
- Thomas A Reh
- Neurobiology and Behavior Program, Department of Biological Structure, University of Washington, School of Medicine, Seattle, USA
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Hasegawa A, Hisatomi O, Yamamoto S, Ono E, Tokunaga F. Stathmin expression during newt retina regeneration. Exp Eye Res 2007; 85:518-27. [PMID: 17707372 DOI: 10.1016/j.exer.2007.07.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2007] [Revised: 06/28/2007] [Accepted: 07/02/2007] [Indexed: 11/17/2022]
Abstract
Japanese common newts (Cynops pyrrhogaster) have high ability to regenerate their injured organs including neural tissues, for example, the neural retina belonging to central nervous system. We attempted to clarify the molecular mechanism underlying the formation of a neural network during newt retina regeneration, and focused on the microtubule dynamics controlled by stathmin family proteins. Stathmin is a small cytoplasmic phosphoprotein known to be a microtubule regulator. We isolated a clone encoding stathmin from the newt. The expression level of stathmin is higher in lung and spleen than in the adult intact retina where stathmin was localized on plexiform layers, the ganglion layer and in photoreceptor inner segments. However, in a regenerating process of the retina, stathmin was upregulated from an early regenerating stage until the retinal layered structure was formed. Immunohistochemical analyses revealed that stathmin existed all around the regenerating retina consisting of retinal progenitor cells. These results suggest that stathmin plays important roles in the construction and maintenance of retinal structure and its neural network, by controlling the proliferation of retinal progenitor cells and the microtubule dynamics of retinal neurons. Moreover, stathmin may function in the dedifferentiating process of retinal pigment epithelium cells.
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Affiliation(s)
- Akiyuki Hasegawa
- Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
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Rizzolo LJ. Development and role of tight junctions in the retinal pigment epithelium. ACTA ACUST UNITED AC 2007; 258:195-234. [PMID: 17338922 DOI: 10.1016/s0074-7696(07)58004-6] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The outer blood-retinal barrier is formed by the retinal pigment epithelium. In any epithelial monolayer, the tight junctions enable the epithelium to form a barrier by joining neighboring cells together and regulating transepithelial diffusion through the paracellular spaces. Tight junctions are complex, dynamic structures that regulate cell proliferation, polarity, and paracellular diffusion. The specific properties of tight junctions vary among epithelia, according to the physiological role of the epithelium. Unlike other epithelia, the apical surface of the retinal pigment epithelium interacts with a solid tissue, the neural retina. Secretions of the developing neural retina regulate the assembly, maturation, and tissue-specific properties of these tight junctions. The slow time course of development allows investigators to dissect the mechanisms of junction assembly and function. These studies are aided by culture systems that model different stages of development.
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Abstract
The retinal pigment epithelium (RPE) maintains retinal function as the metabolic gatekeeper between photoreceptors (PRs) and the choriocapillaries. The RPE and Bruch's membrane (BM) suffer cumulative damage over lifetime, which is thought to induce age-related macular degeneration (AMD) in susceptible individuals. Unlike palliative pharmacologic treatments, replacement of the RPE has a curative potential for AMD. This article reviews mechanisms leading to RPE dysfunction in aging and AMD, laboratory studies on RPE transplantation, and surgical techniques used in AMD patients. Future strategies using ex vivo steps prior to transplantation, BM prosthetics, and stem cell applications are discussed. The functional peculiarity of the macular region, epigenetic phenomena leading to an age-related shift in protein expression, along with the accumulation of lipofuscin may affect the metabolism in the central RPE. Thickening of BM with age decreases its hydraulic conductivity. Drusen are deposits of extracellular material and formed in part by activation of the alternative complement pathway in individuals carrying a mutant allele of complement factor H. AMD likely represents an umbrella term for a disease entity with multifactorial etiology and manifestations. Presently, a slow progressing (dry) non-neovascular atrophic form and a rapidly blinding neovascular (wet) form are discerned. No therapy is currently available for the former, while RPE transplantation and promising (albeit non-causal) anti-angiogenic therapies are available for the latter. The potential of RPE transplantation was demonstrated in animal models. Rejection of allogeneic homologous transplants in patients focused further studies on autologous sources. In vitro studies elucidated cell adhesion and wound healing mechanisms on aged human BM. Currently, autologous RPE, harvested from the midperiphery, is being transplanted as a cell suspension or a patch of RPE and choroid in AMD patients. These techniques have been evaluated from several groups. Autologous RPE transplants may have the disadvantage of carrying the same genetic information that may have led to AMD manifestation. An intermittent culturing step would allow for in vitro therapy of the RPE, its rejuvenation and prosthesis of BM to improve the success RPE transplants. Recent advances in stem cell biology when combined with lessons learned from studies of RPE transplantation are intriguing future therapeutic modalities for AMD patients.
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Affiliation(s)
- Susanne Binder
- Department of Ophthalmology, Rudolf Foundation Clinic, Hospital of the City of Vienna, Vienna, Austria.
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Batts SA, Raphael Y. Transdifferentiation and its applicability for inner ear therapy. Hear Res 2006; 227:41-7. [PMID: 17070000 DOI: 10.1016/j.heares.2006.08.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2006] [Revised: 08/16/2006] [Accepted: 08/31/2006] [Indexed: 11/20/2022]
Abstract
During normal development, cells divide, then differentiate to adopt their individual form and function in an organism. Under most circumstances, mature cells cannot transdifferentiate, changing their fate to adopt a different form and function. Because differentiated cells cannot usually divide, the repair of injuries as well as regeneration largely depends on the activation of stem cell reserves. The mature cochlea is an exception among epithelial cell layers in that it lacks stem cells. Consequently, the sensory hair cells that receive sound information cannot be replaced, and their loss results in permanent hearing impairment. The lack of a spontaneous cell replacement mechanism in the organ of Corti, the mammalian auditory sensory epithelium, has led researchers to investigate circumstances in which transdifferentiation does occur. The hope is that this information can be used to design therapies to replace lost hair cells and restore impaired hearing in humans.
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Affiliation(s)
- Shelley A Batts
- Department of Otolaryngology, Kresge Hearing Research Institute, MSRB-3, Room 9301, Ann Arbor, MI 48109-0648, USA
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Luo Y, Fukuhara M, Weitzman M, Rizzolo LJ. Expression of JAM-A, AF-6, PAR-3 and PAR-6 during the assembly and remodeling of RPE tight junctions. Brain Res 2006; 1110:55-63. [PMID: 16859655 DOI: 10.1016/j.brainres.2006.06.059] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2006] [Revised: 06/16/2006] [Accepted: 06/19/2006] [Indexed: 01/23/2023]
Abstract
The tight junctions of the endothelial and epithelial regions of the blood-brain barrier are regulated by interactions with the neighboring tissue. We examined how the neural retina regulates the assembly of tight junctions in the retinal pigment epithelium (RPE). The proteins JAM-A, AF-6, PAR-3 and PAR-6 have been implicated in the assembly of other epithelial tight junctions. Using chick embryos and primary cell culture, we examined gene expression of these proteins during embryonic development, and whether retinal secretions regulate their expression. Three highly conserved RNA splice sites of AF-6 were identified in chick ocular tissues, but only two were expressed in RPE. JAM-A and AF-6 were expressed at relatively high levels early in development when adherens junctions form, but before tight junctions form. Expression of JAM-A and the AF-6 isoforms actually decreased when tight junctions were forming and expanding. The expression of PAR-3 and PAR-6 was constant. Despite the expression of these proteins in vitro (along with claudins, occludin, ZO-1 and ZO-2), the tight junctional networks that form were discontinuous (Rahner, C., Fukuhara, M., Peng, S., Kojima, S., Rizzolo, L.J., 2004. The apical and basal environments of the retinal pigment epithelium regulate the maturation of tight junctions during development. J. Cell Sci. 117, 3307-3318). The expression of these assembly proteins was unaffected by a retinal conditioned medium that induced the completion of tight junction formation. These data indicate that the early expression of the assembly proteins corresponds to the initial establishment of the adherens and tight junctions, but secretory products of the neural retina must induce the expression of additional proteins to complete the maturation process.
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Affiliation(s)
- Yan Luo
- Department of Surgery, Yale University School of Medicine, New Haven, CT 06520-8062, USA
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Goto T, Hisatomi O, Kotoura M, Tokunaga F. Induced expression of hematopoietic- and neurologic-expressed sequence 1 in retinal pigment epithelial cells during newt retina regeneration. Exp Eye Res 2006; 83:972-80. [PMID: 16797532 DOI: 10.1016/j.exer.2006.05.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2006] [Revised: 04/26/2006] [Accepted: 05/08/2006] [Indexed: 02/06/2023]
Abstract
Newts can regenerate their organs even as adults. For instance, when their neural retinas are completely removed by operation, the remaining retinal pigment epithelial (RPE) cells dedifferentiate to reconstruct neural retinas. To elucidate the molecular mechanisms of newt retina regeneration, we investigated genes upregulated in dedifferentiating RPE cells using differential display methods. We observed that a cDNA fragment of hematopoietic- and neurologic-expressed sequence 1 (Hn1) appeared to be induced within a few days of surgical removal of newt neural retina. Using an anti-HN1 antiserum against the recombinant HN1 protein, we carried out immunohistochemical analyses. The anti-HN1 antiserum recognized the plexiform layers and ganglion cell layer (GCL) but not the RPE cell layer in unoperated (normal) newt retinas. Using a glial fibrillary acidic protein antibody, Hn1 was shown to be possibly expressed in glial cells in normal neural retina. During retina regeneration, immunoreactivity for HN1 appeared in dedifferentiating RPE cells 10 days post-operation, and in retinal progenitor cells 18 days post-operation. Twenty seven days post-operation, HN1 immunoreactivity was localized in the plexiform layers and GCL as in the normal retina. Therefore, HN1 possibly plays an undefined role in dedifferentiating RPE cells and retinal progenitor cells during newt retina regeneration.
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Affiliation(s)
- Tatsushi Goto
- Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
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Kohno RI, Ikeda Y, Yonemitsu Y, Hisatomi T, Yamaguchi M, Miyazaki M, Takeshita H, Ishibashi T, Sueishi K. Sphere formation of ocular epithelial cells in the ciliary body is a reprogramming system for neural differentiation. Brain Res 2006; 1093:54-70. [PMID: 16697356 DOI: 10.1016/j.brainres.2006.03.093] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2005] [Revised: 03/10/2006] [Accepted: 03/17/2006] [Indexed: 10/24/2022]
Abstract
It is well known that neural stem/progenitor cells of the central nervous system (CNS) can proliferate to form neurospheres (CNS-neurospheres) that are positive for nestin, an intermediate filament for neural progenitors. Retinal stem/progenitor properties were also isolated from the ciliary body (CB) of the eye where, as in the CNS, such stem/progenitors also form spheres and have been considered to expand only via expansion by their proliferation even from the single-cell level (called spheres of pigment cells from the ciliary margin: PCM-spheres). We here found a new and distinct process underlying the growth of CB cell-derived spheres (CB-spheres) that is unlike the mechanism of CNS- and PCM-sphere expansion; this new process is a cell proliferation-independent incorporation of neighbor spheres and cells cultured at high density (200 cells/mul). The majority of cells in CB-spheres consisted of nestin-negative epithelia-like cells and started to express nestin during the course of their expansion by high-density cultivation. The growth of CNS-neurospheres was sensitive to a cell-cycle inhibitor, whereas the growth of CB-spheres was not seriously affected by cell proliferation; rather, the spheres grew by incorporating other CB-spheres and nestin-negative adherent cells, the latter of which started to express nestin and lost the expression of epithelial markers after being incorporated. These results indicate that CB-spheres do not form by the accumulation of neural progenitors but rather by a reprogramming system from epithelia-like cells for neural differentiation, a clearly distinct mechanism from sphere formation by single-cell expansion of retinal stem/progenitor populations.
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Affiliation(s)
- Ri-ichiro Kohno
- Division of Pathophysiological and Experimental Pathology, Department of Pathology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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Arresta E, Bernardini S, Bernardini E, Filoni S, Cannata SM. Pigmented epithelium to retinal transdifferentiation and Pax6 expression in larval Xenopus laevis. ACTA ACUST UNITED AC 2006; 303:958-67. [PMID: 16217804 DOI: 10.1002/jez.a.219] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study examines the retinal transdifferentiation (TD) of retinal pigmented epithelium (RPE) fragments dissected from Xenopus laevis larvae and implanted into the vitreous chamber of non-lentectomized host eyes. In these experimental conditions, most RPE implants transformed into polarized vesicles in which the side adjacent to the lens maintained the RPE phenotype, while the side adjacent to the host retina transformed into a laminar retina with the photoreceptor layer facing the cavity of the vesicle and with the ganglionar cell layer facing the host retina. The formation of a new retina with a laminar organization is the result of depigmentation, proliferation and differentiation of progenitor cells under the influence of inductive factors from the host retina. The phases of the TD process were followed using BrdU labelling as a marker of the proliferation phase and using a monoclonal antibody (mAbHP1) as a definitive indicator of retina formation. Pigmented RPE cells do not express Pax6. In the early phase of RPE to retinal TD, all depigmented and proliferating progenitor cells expressed Pax6. Changes in the Pax6 expression pattern became apparent in the early phase of differentiation, when Pax6 expression decreased in the presumptive outer nuclear layer (ONL) of the new-forming retina. Finally, during the late differentiation phase, the ONL, which contains photoreceptors, no longer expressed Pax6, Pax6 expression being confined to the ganglion cell layer and the inner nuclear layer. These results indicate that Pax6 may have different roles during the different phases of RPE to retinal TD, acting as an early retinal determinant and later directing progenitor cell fate.
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Affiliation(s)
- Emiliano Arresta
- Dipartimento di Biologia, Università di Roma "Tor Vergata", I-00133 Rome, Italy
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