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Caparaso SM, Redwine AL, Wachs RA. Engineering a multicompartment in vitro model for dorsal root ganglia phenotypic assessment. J Biomed Mater Res B Appl Biomater 2023; 111:1903-1920. [PMID: 37326300 PMCID: PMC10527728 DOI: 10.1002/jbm.b.35294] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 05/19/2023] [Accepted: 05/31/2023] [Indexed: 06/17/2023]
Abstract
Despite the significant global prevalence of chronic pain, current methods to identify pain therapeutics often fail translation to the clinic. Phenotypic screening platforms rely on modeling and assessing key pathologies relevant to chronic pain, improving predictive capability. Patients with chronic pain often present with sensitization of primary sensory neurons (that extend from dorsal root ganglia [DRG]). During neuronal sensitization, painful nociceptors display lowered stimulation thresholds. To model neuronal excitability, it is necessary to maintain three key anatomical features of DRGs to have a physiologically relevant platform: (1) isolation between DRG cell bodies and neurons, (2) 3D platform to preserve cell-cell and cell-matrix interactions, and (3) presence of native non-neuronal support cells, including Schwann cells and satellite glial cells. Currently, no culture platforms maintain the three anatomical features of DRGs. Herein, we demonstrate an engineered 3D multicompartment device that isolates DRG cell bodies and neurites and maintains native support cells. We observed neurite growth into isolated compartments from the DRG using two formulations of collagen, hyaluronic acid, and laminin-based hydrogels. Further, we characterized the rheological, gelation and diffusivity properties of the two hydrogel formulations and found the mechanical properties mimic native neuronal tissue. Importantly, we successfully limited fluidic diffusion between the DRG and neurite compartment for up to 72 h, suggesting physiological relevance. Lastly, we developed a platform with the capability of phenotypic assessment of neuronal excitability using calcium imaging. Ultimately, our culture platform can screen neuronal excitability, providing a more translational and predictive system to identify novel pain therapeutics to treat chronic pain.
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Affiliation(s)
- Sydney M. Caparaso
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln Nebraska, USA
| | - Adan L. Redwine
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln Nebraska, USA
| | - Rebecca A. Wachs
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln Nebraska, USA
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Astolfi G, Ciavarella C, Valente S, Coslovi C, Iannetta D, Fontana L, Pasquinelli G, Versura P. Human glial müller and umbilical vein endothelial cell coculture as an in vitro model to investigate retinal oxidative damage. A morphological and molecular assessment. Microsc Res Tech 2023; 86:439-451. [PMID: 36579625 DOI: 10.1002/jemt.24284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 11/29/2022] [Accepted: 12/17/2022] [Indexed: 12/30/2022]
Abstract
The aim of this study was to optimize a coculture in vitro model established between the human Müller glial cells and human umbilical vein endothelial cells, mimicking the inner blood-retinal barrier, and to explore its resistance to damage induced by oxidative stress. A spontaneously immortalized human Müller cell line MIO-M1 and human umbilical vein endothelial cells (HUVEC) were plated together at a density ratio 1:1 and maintained up to the 8th passage (p8). The MIO-M1/HUVECs p1 through p8 were treated with increasing concentrations (range 200-800 μM) of H2 O2 to evaluate oxidative stress induced damage and comparing data with single cell cultures. The following features were assayed p1 through p8: doubling time maintenance, cell viability using MTS assay, ultrastructure of cell-cell contacts, immunofluorescence for Vimentin and GFAP, molecular biology (q-PCR) for GFAP and CD31 mRNA. MIO-M1/HUVECs cocultures maintained distinct cell cytotype up to p8 as shown by flow cytometry analysis, without evidence of cross activation, displaying cell-cell tight junctions mimicking those found in human retina, only acquiring a slight resistance to oxidative stress induction over the passages. This MIO-M1/HUVECs coculture represents a simple, reproducible and affordable model for in vitro studies on oxidative stress-induced retinal damages.
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Affiliation(s)
- Gloria Astolfi
- Ophthalmology Unit, DIMES, Alma Mater Studiorum Università di Bologna, Italy
| | - Carmen Ciavarella
- Laboratory of Clinical Pathology, Department of Experimental, Diagnostic and Specialty Medicine (DIMES), University of Bologna, Italy
| | - Sabrina Valente
- Laboratory of Clinical Pathology, Department of Experimental, Diagnostic and Specialty Medicine (DIMES), University of Bologna, Italy
| | - Chiara Coslovi
- Ophthalmology Unit, DIMES, Alma Mater Studiorum Università di Bologna, Italy
- IRCCS Azienda Ospedaliero-Universitaria di Bologna, Italy
| | - Danilo Iannetta
- Ophthalmology Unit, DIMES, Alma Mater Studiorum Università di Bologna, Italy
- IRCCS Azienda Ospedaliero-Universitaria di Bologna, Italy
| | - Luigi Fontana
- Ophthalmology Unit, DIMES, Alma Mater Studiorum Università di Bologna, Italy
- IRCCS Azienda Ospedaliero-Universitaria di Bologna, Italy
| | - Gianandrea Pasquinelli
- Laboratory of Clinical Pathology, Department of Experimental, Diagnostic and Specialty Medicine (DIMES), University of Bologna, Italy
- IRCCS Azienda Ospedaliero-Universitaria di Bologna, Italy
| | - Piera Versura
- Ophthalmology Unit, DIMES, Alma Mater Studiorum Università di Bologna, Italy
- IRCCS Azienda Ospedaliero-Universitaria di Bologna, Italy
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Peña JS, Vazquez M. Harnessing the Neuroprotective Behaviors of Müller Glia for Retinal Repair. FRONT BIOSCI-LANDMRK 2022; 27:169. [PMID: 35748245 PMCID: PMC9639582 DOI: 10.31083/j.fbl2706169] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 04/18/2022] [Accepted: 05/05/2022] [Indexed: 11/29/2022]
Abstract
Progressive and irreversible vision loss in mature and aging adults creates a health and economic burden, worldwide. Despite the advancements of many contemporary therapies to restore vision, few approaches have considered the innate benefits of gliosis, the endogenous processes of retinal repair that precede vision loss. Retinal gliosis is fundamentally driven by Müller glia (MG) and is characterized by three primary cellular mechanisms: hypertrophy, proliferation, and migration. In early stages of gliosis, these processes have neuroprotective potential to halt the progression of disease and encourage synaptic activity among neurons. Later stages, however, can lead to glial scarring, which is a hallmark of disease progression and blindness. As a result, the neuroprotective abilities of MG have remained incompletely explored and poorly integrated into current treatment regimens. Bioengineering studies of the intrinsic behaviors of MG hold promise to exploit glial reparative ability, while repressing neuro-disruptive MG responses. In particular, recent in vitro systems have become primary models to analyze individual gliotic processes and provide a stepping stone for in vivo strategies. This review highlights recent studies of MG gliosis seeking to harness MG neuroprotective ability for regeneration using contemporary biotechnologies. We emphasize the importance of studying gliosis as a reparative mechanism, rather than disregarding it as an unfortunate clinical prognosis in diseased retina.
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Affiliation(s)
- Juan S. Peña
- Department of Biomedical Engineering, Rutgers, The State
University of New Jersey, Piscataway (08854), New Jersey, USA
| | - Maribel Vazquez
- Department of Biomedical Engineering, Rutgers, The State
University of New Jersey, Piscataway (08854), New Jersey, USA
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4
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Gallo RA, Qureshi F, Strong TA, Lang SH, Pino KA, Dvoriantchikova G, Pelaez D. Derivation and Characterization of Murine and Amphibian Müller Glia Cell Lines. Transl Vis Sci Technol 2022; 11:4. [PMID: 35377941 PMCID: PMC8994200 DOI: 10.1167/tvst.11.4.4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Purpose Müller glia (MG) in the retina of Xenopus laevis (African clawed frog) reprogram to a transiently amplifying retinal progenitor state after an injury. These progenitors then give rise to new retinal neurons. In contrast, mammalian MG have a restricted neurogenic capacity and undergo reactive gliosis after injury. This study sought to establish MG cell lines from the regeneration-competent frog and the regeneration-deficient mouse. Methods MG were isolated from postnatal day 5 GLAST-CreERT; Rbfl/fl mice and from adult (3–5 years post-metamorphic) Xlaevis. Serial adherent subculture resulted in spontaneously immortalized cells and the establishment of two MG cell lines: murine retinal glia 17 (RG17) and Xenopus glia 69 (XG69). They were characterized for MG gene and protein expression by qPCR, immunostaining, and Western blot. Purinergic signaling was assessed with calcium imaging. Pharmacological perturbations with 2’-3’-O-(4-benzoylbenzoyl) adenosine 5’-triphosphate (BzATP) and KN-62 were performed on RG17 cells. Results RG17 and XG69 cells express several MG markers and retain purinergic signaling. Pharmacological perturbations of intracellular calcium responses with BzATP and KN-62 suggest that the ionotropic purinergic receptor P2X7 is present and functional in RG17 cells. Stimulation of XG69 cells with adenosine triphosphate–induced calcium responses in a dose-dependent manner. Conclusions We report the characterization of RG17 and XG69, two novel MG cell lines from species with significantly disparate retinal regenerative capabilities. Translational Relevance RG17 and XG69 cell line models will aid comparative studies between species endowed with varied regenerative capacity and will facilitate the development of new cell-based strategies for treating retinal degenerative diseases.
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Affiliation(s)
- Ryan A Gallo
- Dr. Nasser Ibrahim Al-Rashid Orbital Vision Research Center, Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, USA.,Medical Scientist Training Program, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Farhan Qureshi
- Medical Scientist Training Program, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Thomas A Strong
- Dr. Nasser Ibrahim Al-Rashid Orbital Vision Research Center, Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Steven H Lang
- Dr. Nasser Ibrahim Al-Rashid Orbital Vision Research Center, Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Kevin A Pino
- Dr. Nasser Ibrahim Al-Rashid Orbital Vision Research Center, Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Galina Dvoriantchikova
- Dr. Nasser Ibrahim Al-Rashid Orbital Vision Research Center, Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Daniel Pelaez
- Dr. Nasser Ibrahim Al-Rashid Orbital Vision Research Center, Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, USA.,Department of Cell Biology, University of Miami Miller School of Medicine, Miami, FL, USA
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Peña JS, Vazquez M. VEGF Upregulates EGFR Expression to Stimulate Chemotactic Behaviors in the rMC-1 Model of Müller Glia. Brain Sci 2020; 10:E330. [PMID: 32485834 PMCID: PMC7348795 DOI: 10.3390/brainsci10060330] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 03/28/2020] [Accepted: 05/27/2020] [Indexed: 12/14/2022] Open
Abstract
Progressive vision loss in adults has become increasingly prevalent worldwide due to retinopathies associated with aging, genetics, and epigenetic factors that damage the retinal microvasculature. Insufficient supply of oxygen and/or nutrients upregulates factors such as vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF), which can induce abnormal angiogenesis and damage the structural arrangement of the retinal blood barrier (BRB). Müller glia (MG) regulate the diffusion of essential compounds across the BRB and respond to retinal insults via reactive gliosis, which includes cell hypertrophy, migration, and/or proliferation near areas of elevated VEGF concentration. Increasing concentrations of exogenous VEGF, upregulated by retinal pigmented epithelium cells, and endogenous epidermal growth factor receptor (EGF-R) stimulation in MG, implicated in MG proliferative and migratory behavior, often lead to progressive and permanent vision loss. Our project examined the chemotactic responses of the rMC-1 cell line, a mammalian MG model, toward VEGF and EGF signaling fields in transwell assays, and within respective concentration gradient fields produced in the glia line (gLL) microfluidic system previously described by our group. rMC-1 receptor expression in defined ligand fields was also evaluated using quantitative polymerase chain reaction (qPCR) and immunocytochemical staining. Results illustrate dramatic increases in rMC-1 chemotactic responses towards EGF gradient fields after pre-treatment with VEGF. In addition, qPCR illustrated significant upregulation of EGF-R upon VEGF pre-treatment, which was higher than that induced by its cognate ligand, EGF. These results suggest interplay of molecular pathways between VEGF and EGF-R that have remained understudied in MG but are significant to the development of effective anti-VEGF treatments needed for a variety of retinopathies.
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Affiliation(s)
| | - Maribel Vazquez
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA;
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Webster MK, Barnett BJ, Stanchfield ML, Paris JR, Webster SE, Cooley-Themm CA, Levine EM, Otteson DC, Linn CL. Stimulation of Retinal Pigment Epithelium With an α7 nAChR Agonist Leads to Müller Glia Dependent Neurogenesis in the Adult Mammalian Retina. Invest Ophthalmol Vis Sci 2019; 60:570-579. [PMID: 30721274 PMCID: PMC6363405 DOI: 10.1167/iovs.18-25722] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Purpose The adult mammalian retina is typically incapable of regeneration when damaged by disease or trauma. Restoration of function would require generation of new adult neurons, something that until recently, mammals were thought to be incapable of doing. However, previous studies from this laboratory have shown that the α7 nicotinic acetylcholine receptor (α7 nAChR) agonist, PNU-282987, induces cell cycle reentry of Müller glia and generation of mature retinal neurons in adult rats, in the absence of detectible injury. This study analyzes how PNU-282987 treatment in RPE leads to robust BrdU incorporation in Müller glia in adult mice and leads to generation of Müller-derived retinal progenitors and neuronal differentiation. Methods Retinal BrdU incorporation was examined after eye drop application of PNU-282987 in adult wild-type and transgenic mice that contain tamoxifen-inducible tdTomato Müller glia, or after intraocular injection of conditioned medium from PNU-282987–treated cultured RPE cells. Results PNU-282987 induced robust incorporation of BrdU in all layers of the adult mouse retina. The α7 nAChR agonist was found to stimulate cell cycle reentry of Müller glia and their generation of new retinal progenitors indirectly, via the RPE, in an α7 nAChR-dependent fashion. Conclusions The results from this study point to RPE as a contributor to Müller glial neurogenic responses. The manipulation of the RPE to stimulate retinal neurogenesis offers a new direction for developing novel and potentially transformative treatments to reverse the loss of neurons associated with neurodegenerative disease, traumatic injury, or aging.
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Affiliation(s)
- Mark K Webster
- Western Michigan University, Department of Biological Sciences, Kalamazoo, Michigan, United States
| | - Betty J Barnett
- Western Michigan University, Department of Biological Sciences, Kalamazoo, Michigan, United States
| | - Megan L Stanchfield
- Western Michigan University, Department of Biological Sciences, Kalamazoo, Michigan, United States
| | - Joshua R Paris
- Western Michigan University, Department of Biological Sciences, Kalamazoo, Michigan, United States
| | - Sarah E Webster
- Western Michigan University, Department of Biological Sciences, Kalamazoo, Michigan, United States
| | - Cynthia A Cooley-Themm
- Western Michigan University, Department of Biological Sciences, Kalamazoo, Michigan, United States
| | - Edward M Levine
- Vanderbilt University Medical Center, Vanderbilt Eye Institute, Nashville, Tennessee, United States
| | - Deborah C Otteson
- University of Houston College of Optometry, Department of Physiological Optics and Vision Science, Houston, Texas, United States
| | - Cindy L Linn
- Western Michigan University, Department of Biological Sciences, Kalamazoo, Michigan, United States
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7
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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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Ren Y, Mlodzianoski MJ, Lee AC, Huang F, Suter DM. A low-cost microwell device for high-resolution imaging of neurite outgrowth in 3D. J Neural Eng 2018; 15:035001. [PMID: 29363623 DOI: 10.1088/1741-2552/aaaa32] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
OBJECTIVE Current neuronal cell culture is mostly performed on two-dimensional (2D) surfaces, which lack many of the important features of the native environment of neurons, including topographical cues, deformable extracellular matrix, and spatial isotropy or anisotropy in three dimensions. Although three-dimensional (3D) cell culture systems provide a more physiologically relevant environment than 2D systems, their popularity is greatly hampered by the lack of easy-to-make-and-use devices. We aim to develop a widely applicable 3D culture procedure to facilitate the transition of neuronal cultures from 2D to 3D. APPROACH We made a simple microwell device for 3D neuronal cell culture that is inexpensive, easy to assemble, and fully compatible with commonly used imaging techniques, including super-resolution microscopy. MAIN RESULTS We developed a novel gel mixture to support 3D neurite regeneration of Aplysia bag cell neurons, a system that has been extensively used for quantitative analysis of growth cone dynamics in 2D. We found that the morphology and growth pattern of bag cell growth cones in 3D culture closely resemble the ones of growth cones observed in vivo. We demonstrated the capability of our device for high-resolution imaging of cytoskeletal and signaling proteins as well as organelles. SIGNIFICANCE Neuronal cell culture has been a valuable tool for neuroscientists to study the behavior of neurons in a controlled environment. Compared to 2D, neurons cultured in 3D retain the majority of their native characteristics, while offering higher accessibility, control, and repeatability. We expect that our microwell device will facilitate a wider adoption of 3D neuronal cultures to study the mechanisms of neurite regeneration.
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Affiliation(s)
- Yuan Ren
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, United States of America
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9
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Watson PMD, Kavanagh E, Allenby G, Vassey M. Bioengineered 3D Glial Cell Culture Systems and Applications for Neurodegeneration and Neuroinflammation. SLAS DISCOVERY 2017; 22:583-601. [PMID: 28346104 DOI: 10.1177/2472555217691450] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Neurodegeneration and neuroinflammation are key features in a range of chronic central nervous system (CNS) diseases such as Alzheimer's and Parkinson's disease, as well as acute conditions like stroke and traumatic brain injury, for which there remains significant unmet clinical need. It is now well recognized that current cell culture methodologies are limited in their ability to recapitulate the cellular environment that is present in vivo, and there is a growing body of evidence to show that three-dimensional (3D) culture systems represent a more physiologically accurate model than traditional two-dimensional (2D) cultures. Given the complexity of the environment from which cells originate, and their various cell-cell and cell-matrix interactions, it is important to develop models that can be controlled and reproducible for drug discovery. 3D cell models have now been developed for almost all CNS cell types, including neurons, astrocytes, microglia, and oligodendrocyte cells. This review will highlight a number of current and emerging techniques for the culture of astrocytes and microglia, glial cell types with a critical role in neurodegenerative and neuroinflammatory conditions. We describe recent advances in glial cell culture using electrospun polymers and hydrogel macromolecules, and highlight how these novel culture environments influence astrocyte and microglial phenotypes in vitro, as compared to traditional 2D systems. These models will be explored to illuminate current trends in the techniques used to create 3D environments for application in research and drug discovery focused on astrocytes and microglial cells.
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10
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Regulation of Stem Cell Properties of Müller Glia by JAK/STAT and MAPK Signaling in the Mammalian Retina. Stem Cells Int 2017; 2017:1610691. [PMID: 28194183 PMCID: PMC5282447 DOI: 10.1155/2017/1610691] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 12/21/2016] [Indexed: 12/15/2022] Open
Abstract
In humans and other mammals, the neural retina does not spontaneously regenerate, and damage to the retina that kills retinal neurons results in permanent blindness. In contrast to embryonic stem cells, induced pluripotent stem cells, and embryonic/fetal retinal stem cells, Müller glia offer an intrinsic cellular source for regenerative strategies in the retina. Müller glia are radial glial cells within the retina that maintain retinal homeostasis, buffer ion flux associated with phototransduction, and form the blood/retinal barrier within the retina proper. In injured or degenerating retinas, Müller glia contribute to gliotic responses and scar formation but also show regenerative capabilities that vary across species. In the mammalian retina, regenerative responses achieved to date remain insufficient for potential clinical applications. Activation of JAK/STAT and MAPK signaling by CNTF, EGF, and FGFs can promote proliferation and modulate the glial/neurogenic switch. However, to achieve clinical relevance, additional intrinsic and extrinsic factors that restrict or promote regenerative responses of Müller glia in the mammalian retina must be identified. This review focuses on Müller glia and Müller glial-derived stem cells in the retina and phylogenetic differences among model vertebrate species and highlights some of the current progress towards understanding the cellular mechanisms regulating their regenerative response.
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Dermutz H, Thompson-Steckel G, Forró C, de Lange V, Dorwling-Carter L, Vörös J, Demkó L. Paper-based patterned 3D neural cultures as a tool to study network activity on multielectrode arrays. RSC Adv 2017. [DOI: 10.1039/c7ra00971b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
High-throughput platform targeting activity patterns of 3D neural cultures with arbitrary topology, by combining network-wide intracellular and local extracellular signals.
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Affiliation(s)
- Harald Dermutz
- Laboratory of Biosensors and Bioelectronics
- Institute for Biomedical Engineering
- ETH Zurich
- CH-8092 Zurich
- Switzerland
| | - Greta Thompson-Steckel
- Laboratory of Biosensors and Bioelectronics
- Institute for Biomedical Engineering
- ETH Zurich
- CH-8092 Zurich
- Switzerland
| | - Csaba Forró
- Laboratory of Biosensors and Bioelectronics
- Institute for Biomedical Engineering
- ETH Zurich
- CH-8092 Zurich
- Switzerland
| | - Victoria de Lange
- Laboratory of Biosensors and Bioelectronics
- Institute for Biomedical Engineering
- ETH Zurich
- CH-8092 Zurich
- Switzerland
| | - Livie Dorwling-Carter
- Laboratory of Biosensors and Bioelectronics
- Institute for Biomedical Engineering
- ETH Zurich
- CH-8092 Zurich
- Switzerland
| | - János Vörös
- Laboratory of Biosensors and Bioelectronics
- Institute for Biomedical Engineering
- ETH Zurich
- CH-8092 Zurich
- Switzerland
| | - László Demkó
- Laboratory of Biosensors and Bioelectronics
- Institute for Biomedical Engineering
- ETH Zurich
- CH-8092 Zurich
- Switzerland
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Patel M, Moon HJ, Jung BK, Jeong B. Microsphere-Incorporated Hybrid Thermogel for Neuronal Differentiation of Tonsil Derived Mesenchymal Stem Cells. Adv Healthc Mater 2015; 4:1565-74. [PMID: 26033880 DOI: 10.1002/adhm.201500224] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 04/30/2015] [Indexed: 12/20/2022]
Abstract
Neuronal differentiation of tonsil-derived mesenchymal stem cells (TMSCs) is investigated in a 3D hybrid system. The hybrid system is prepared by increasing the temperature of poly(ethylene glycol)-poly(l-alanine) aqueous solution to 37 °C through the heat-induced sol-to-gel transition, in which TMSCs and growth factor releasing microspheres are suspended. The in situ formed gel exhibits a modulus of 800 Pa at 37 °C, similar to that of brain tissue, and it is robust enough to hold the microspheres and cells during the 3D culture of TMSCs. The neuronal growth factors are released over 12-18 d, and the TMSCs in a spherical shape initially undergo multipolar elongation during the 3D culture. Significantly higher expressions of the neuronal biomarkers such as nuclear receptor related protein (Nurr-1), neuron specific enolase, microtubule associated protein-2, neurofilament-M, and glial fibrillary acidic protein are observed in both mRNA level and protein level in the hybrid systems than in the control experiments. This study proves the significance of a controlled drug delivery concept in tissue engineering or regenerative medicine, and a 3D hybrid system with controlled release of growth factors from microspheres in a thermogel can be a very promising tool.
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Affiliation(s)
- Madhumita Patel
- Department of Chemistry and Nano Science; Ewha Womans University; 52 Ewhayeodae-gil Seodaemun-gu Seoul 120-750 South Korea
| | - Hyo Jung Moon
- Department of Chemistry and Nano Science; Ewha Womans University; 52 Ewhayeodae-gil Seodaemun-gu Seoul 120-750 South Korea
| | - Bo Kyung Jung
- Department of Chemistry and Nano Science; Ewha Womans University; 52 Ewhayeodae-gil Seodaemun-gu Seoul 120-750 South Korea
| | - Byeongmoon Jeong
- Department of Chemistry and Nano Science; Ewha Womans University; 52 Ewhayeodae-gil Seodaemun-gu Seoul 120-750 South Korea
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13
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Corso-Díaz X, Simpson EM. Nr2e1 regulates retinal lamination and the development of Müller glia, S-cones, and glycineric amacrine cells during retinogenesis. Mol Brain 2015; 8:37. [PMID: 26092486 PMCID: PMC4475312 DOI: 10.1186/s13041-015-0126-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2015] [Accepted: 05/23/2015] [Indexed: 12/25/2022] Open
Abstract
Background Nr2e1 is a nuclear receptor crucial for neural stem cell proliferation and maintenance. In the retina, lack of Nr2e1 results in premature neurogenesis, aberrant blood vessel formation and dystrophy. However, the specific role of Nr2e1 in the development of different retinal cell types and its cell-autonomous and non-cell autonomous function(s) during eye development are poorly understood. Results Here, we studied the retinas of P7 and P21 Nr2e1frc/frc mice and Nr2e1+/+ ↔ Nr2e1frc/frc chimeras. We hypothesized that Nr2e1 differentially regulates the development of various retinal cell types, and thus the cellular composition of Nr2e1frc/frc retinas does not simply reflect an overrepresentation of cells born early and underrepresentation of cells born later as a consequence of premature neurogenesis. In agreement with our hypothesis, lack of Nr2e1 resulted in increased numbers of glycinergic amacrine cells with no apparent increase in other amacrine sub-types, normal numbers of Müller glia, the last cell-type to be generated, and increased numbers of Nr2e1frc/frc S-cones in chimeras. Furthermore, Nr2e1frc/frc Müller glia were mispositioned in the retina and misexpressed the ganglion cell-specific transcription factor Brn3a. Nr2e1frc/frc retinas also displayed lamination defects including an ectopic neuropil forming an additional inner plexiform layer. In chimeric mice, retinal thickness was rescued by 34 % of wild-type cells and Nr2e1frc/frc dystrophy-related phenotypes were no longer evident. However, the formation of an ectopic neuropil, misexpression of Brn3a in Müller glia, and abnormal cell numbers in the inner and outer nuclear layers at P7 were not rescued by wild-type cells. Conclusions Together, these results show that Nr2e1, in addition to having a role in preventing premature cell cycle exit, participates in several other developmental processes during retinogenesis including neurite organization in the inner retina and development of glycinergic amacrine cells, S-cones, and Müller glia. Nr2e1 also regulates various aspects of Müller glia differentiation cell-autonomously. However, Nr2e1 does not have a cell-autonomous role in preventing retinal dystrophy. Thus, Nr2e1 regulates processes involved in neurite development and terminal retinal cell differentiation. Electronic supplementary material The online version of this article (doi:10.1186/s13041-015-0126-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ximena Corso-Díaz
- Centre for Molecular Medicine and Therapeutics at the Child and Family Research Institute, University of British Columbia, 950 W 28 Ave, Vancouver, V5Z 4H4, BC, Canada.,Genetics Graduate Program, University of British Columbia, Vancouver, V6T 1Z2, BC, Canada
| | - Elizabeth M Simpson
- Centre for Molecular Medicine and Therapeutics at the Child and Family Research Institute, University of British Columbia, 950 W 28 Ave, Vancouver, V5Z 4H4, BC, Canada. .,Genetics Graduate Program, University of British Columbia, Vancouver, V6T 1Z2, BC, Canada. .,Department of Medical Genetics, University of British Columbia, Vancouver, V6T 1Z3, BC, Canada. .,Department of Psychiatry, University of British Columbia, Vancouver, V6T 2A1, BC, Canada.
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Neural differentiation of pluripotent cells in 3D alginate-based cultures. Biomaterials 2014; 35:4636-45. [PMID: 24631250 DOI: 10.1016/j.biomaterials.2014.02.039] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Accepted: 02/21/2014] [Indexed: 12/14/2022]
Abstract
Biomaterial-supported culture methods, allowing for directed three-dimensional differentiation of stem cells are an alternative to canonical two-dimensional cell cultures. In this paper, we evaluate the suitability of alginate for three-dimensional cultures to enhance differentiation of mouse embryonic stem cells (mESCs) towards neural lineages. We tested whether encapsulation of mESCs within alginate beads could support and/or enhance neural differentiation with respect to two-dimensional cultures. We encapsulated cells in beads of alginate with or without modification by fibronectin (Fn) or hyaluronic acid (HA). Gene expression analysis showed that cells grown in alginate and alginate-HA present increased differentiation toward neural lineages with respect to the two-dimensional control and to Fn group. Immunocytochemistry analyses confirmed these results, further showing terminal differentiation of neurons as seen by the expression of synaptic markers and markers of different neuronal subtypes. Our data show that alginate, alone or modified, is a suitable biomaterial to promote in vitro differentiation of pluripotent cells toward neural fates.
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15
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Unachukwu UJ, Sauane M, Vazquez M, Redenti S. Microfluidic generated EGF-gradients induce chemokinesis of transplantable retinal progenitor cells via the JAK/STAT and PI3kinase signaling pathways. PLoS One 2013; 8:e83906. [PMID: 24376770 PMCID: PMC3871684 DOI: 10.1371/journal.pone.0083906] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 11/10/2013] [Indexed: 11/18/2022] Open
Abstract
A growing number of studies are evaluating retinal progenitor cell (RPC) transplantation as an approach to repair retinal degeneration and restore visual function. To advance cell-replacement strategies for a practical retinal therapy, it is important to define the molecular and biochemical mechanisms guiding RPC motility. We have analyzed RPC expression of the epidermal growth factor receptor (EGFR) and evaluated whether exposure to epidermal growth factor (EGF) can coordinate motogenic activity in vitro. Using Boyden chamber analysis as an initial high-throughput screen, we determined that RPC motility was optimally stimulated by EGF concentrations in the range of 20-400 ng/ml, with decreased stimulation at higher concentrations, suggesting concentration-dependence of EGF-induced motility. Using bioinformatics analysis of the EGF ligand in a retina-specific gene network pathway, we predicted a chemotactic function for EGF involving the MAPK and JAK-STAT intracellular signaling pathways. Based on targeted inhibition studies, we show that ligand binding, phosphorylation of EGFR and activation of the intracellular STAT3 and PI3kinase signaling pathways are necessary to drive RPC motility. Using engineered microfluidic devices to generate quantifiable steady-state gradients of EGF coupled with live-cell tracking, we analyzed the dynamics of individual RPC motility. Microfluidic analysis, including center of mass and maximum accumulated distance, revealed that EGF induced motility is chemokinetic with optimal activity observed in response to low concentration gradients. Our combined results show that EGFR expressing RPCs exhibit enhanced chemokinetic motility in the presence of low nanomole levels of EGF. These findings may serve to inform further studies evaluating the extent to which EGFR activity, in response to endogenous ligand, drives motility and migration of RPCs in retinal transplantation paradigms.
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Affiliation(s)
- Uchenna J. Unachukwu
- Biochemistry Doctoral Program, The Graduate School and University Center, City University of New York, New York, New York, United States of America
| | - Moira Sauane
- Department of Biological Sciences, Herbert Lehman College, City University of New York, Bronx, New York, United States of America
| | - Maribel Vazquez
- Department of Biomedical Engineering, City College of New York, City University of New York, New York, New York, United States of America
| | - Stephen Redenti
- Biochemistry Doctoral Program, The Graduate School and University Center, City University of New York, Department of Biological Sciences, Herbert Lehman College, City University of New York, Bronx, New York, United States of America
- * E-mail:
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16
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Odawara A, Gotoh M, Suzuki I. Control of neural network patterning using collagen gel photothermal etching. LAB ON A CHIP 2013; 13:2040-2046. [PMID: 23615759 DOI: 10.1039/c3lc00036b] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Two-dimensional (2D) micropatterning techniques have been developed to guide dissociated neurons into predefined distributions on solid substrates, such as glass and plastic. Micropatterning methods using three-dimensional (3D) substrates or scaffolds that reproduce aspects of the in vivo microenvironment could facilitate the engineering of functional tissues for transplantation or more robust experimental models. We developed a 3D collagen gel photothermal etching method using an infrared laser that precisely controls the area of cell adhesion and neurite projection by etching a small targeted section of the collage gel. It was then possible to guide neural network formation under microscopic observation. After conventional cell seeding, we succeeded in creating isolated 3D networks, while controlling (1) the number of each neural subtype (neurons, glia, and fluorescently-labeled neurons) and (2) the direction of neurite elongation. Neurons seeded on a 10-μm-thick collagen gel survived longer and projected greater numbers of neurites than neurons growing on 2D culture substrates. Intracellular Ca(2+) imaging revealed both synchronous and discordant oscillations in different neuronal populations that suggested the pattern and strength of synaptic connectivity. This photothermal etching technique allows for the creation of designed 3D neural networks during cultivation for use in studies of synaptic transmission, neuron-glial signaling, pathogenesis, and drug responses.
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Affiliation(s)
- Aoi Odawara
- Graduate School of Bionics, Tokyo University of Technology, 1404-1 katakura, Hachioji, Tokyo 192-0982, Japan
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17
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Caprini A, Silva D, Zanoni I, Cunha C, Volontè C, Vescovi A, Gelain F. A novel bioactive peptide: assessing its activity over murine neural stem cells and its potential for neural tissue engineering. N Biotechnol 2013; 30:552-62. [PMID: 23541699 DOI: 10.1016/j.nbt.2013.03.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 02/11/2013] [Accepted: 03/18/2013] [Indexed: 01/16/2023]
Abstract
The design of biomimetic scaffolds suitable for cell-based therapies is a fundamental step for the regeneration of the damaged nervous system; indeed growing interest is focusing on the discovery of peptide sequences to modulate the fate of transplanted cells and, in particular, the differentiation outcome of multipotent neural stem cells. By applying the Phage Display technique to murine neural stem cells we isolated a peptide, KLPGWSG, present in proteins involved in both stem cell maintenance and differentiation. We show that KLPGWSG binds molecules expressed on the cell surface of murine adult neural stem cells, thus may potentially be involved in stem cell fate determination. Indeed we demonstrated that this peptide in solution enhances per se cell differentiation toward the neuronal phenotype. Hence, we synthesized two LDLK-12-based self-assembling peptides functionalized with KLPGWSG peptide (KLP and Ac-KLP) and characterized them via atomic force microscopy, rheometry and circular dichroism, obtaining nanostructured hydrogels supporting murine neural stem cells differentiation in vitro. Interestingly, we demonstrated that, when scaffold stiffness is comparable to that of the brain in vivo, the Ac-KLP SAP-based scaffold enhances the neuronal differentiation of neural stem cells. These evidences place both KLPGWSG and the functionalized self-assembling peptide Ac-KLP as promising candidates for, respectively, biomimetic studies and stem cell therapies for nervous regeneration.
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Affiliation(s)
- Andrea Caprini
- Center for Nanomedicine and Tissue Engineering, A.O. Ospedale Niguarda Ca' Granda, Milan 20162, Italy
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18
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Odawara A, Gotoh M, Suzuki I. A three-dimensional neuronal culture technique that controls the direction of neurite elongation and the position of soma to mimic the layered structure of the brain. RSC Adv 2013. [DOI: 10.1039/c3ra44757j] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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19
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Distinct neurogenic potential in the retinal margin and the pars plana of mammalian eye. J Neurosci 2012; 32:12797-807. [PMID: 22973003 DOI: 10.1523/jneurosci.0118-12.2012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Unlike many other vertebrates, a healthy mammalian retina does not grow throughout life and lacks a ciliary margin zone capable of actively generating new neurons. The isolation of stem-like cells from the ciliary epithelium has led to speculation that the mammalian retina and/or surrounding tissues may retain neurogenic potential capable of responding to retinal damage. Using genetically altered mouse lines with varying degrees of retinal ganglion cell loss, we show that the retinal margin responds to ganglion cell loss by prolonging specific neurogenic activity, as characterized by increased numbers of Atoh7(LacZ)-expressing cells. The extent of neurogenic activity correlated with the degree of ganglion cell deficiency. In the pars plana, but not the retinal margin, cells remain proliferative into adulthood, marking the junction of pars plana and retinal margin as a niche capable of producing proliferative cells in the mammalian retina and a potential cellular source for retinal regeneration.
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20
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Saracino GAA, Cigognini D, Silva D, Caprini A, Gelain F. Nanomaterials design and tests for neural tissue engineering. Chem Soc Rev 2012; 42:225-62. [PMID: 22990473 DOI: 10.1039/c2cs35065c] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Nanostructured scaffolds recently showed great promise in tissue engineering: nanomaterials can be tailored at the molecular level and scaffold morphology may more closely resemble features of extracellular matrix components in terms of porosity, framing and biofunctionalities. As a consequence, both biomechanical properties of scaffold microenvironments and biomaterial-protein interactions can be tuned, allowing for improved transplanted cell engraftment and better controlled diffusion of drugs. Easier said than done, a nanotech-based regenerative approach encompasses different fields of know-how, ranging from in silico simulations, nanomaterial synthesis and characterization at the nano-, micro- and mesoscales to random library screening methods (e.g. phage display), in vitro cellular-based experiments and validation in animal models of the target injury. All of these steps of the "assembly line" of nanostructured scaffolds are tightly interconnected both in their standard analysis techniques and in their most recent breakthroughs: indeed their efforts have to jointly provide the deepest possible analyses of the diverse facets of the challenging field of neural tissue engineering. The purpose of this review is therefore to provide a critical overview of the recent advances in and drawbacks and potential of each mentioned field, contributing to the realization of effective nanotech-based therapies for the regeneration of peripheral nerve transections, spinal cord injuries and brain traumatic injuries. Far from being the ultimate overview of such a number of topics, the reader will acknowledge the intrinsic complexity of the goal of nanotech tissue engineering for a conscious approach to the development of a regenerative therapy and, by deciphering the thread connecting all steps of the research, will gain the necessary view of its tremendous potential if each piece of stone is correctly placed to work synergically in this impressive mosaic.
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Affiliation(s)
- Gloria A A Saracino
- Center for Nanomedicine and Tissue Engineering, A.O. Ospedale Niguarda Cà Granda, Milan, 20162, Italy
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21
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West EL, Gonzalez-Cordero A, Hippert C, Osakada F, Martinez-Barbera JP, Pearson RA, Sowden JC, Takahashi M, Ali RR. Defining the integration capacity of embryonic stem cell-derived photoreceptor precursors. Stem Cells 2012; 30:1424-35. [PMID: 22570183 PMCID: PMC3580313 DOI: 10.1002/stem.1123] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Retinal degeneration is a leading cause of irreversible blindness in the developed world. Differentiation of retinal cells, including photoreceptors, from both mouse and human embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), potentially provide a renewable source of cells for retinal transplantation. Previously, we have shown both the functional integration of transplanted rod photoreceptor precursors, isolated from the postnatal retina, in the adult murine retina, and photoreceptor cell generation by stepwise treatment of ESCs with defined factors. In this study, we assessed the extent to which this protocol recapitulates retinal development and also evaluated differentiation and integration of ESC-derived retinal cells following transplantation using our established procedures. Optimized retinal differentiation via isolation of Rax.GFP retinal progenitors recreated a retinal niche and increased the yield of Crx(+) and Rhodopsin(+) photoreceptors. Rod birth peaked at day 20 of culture and expression of the early photoreceptor markers Crx and Nrl increased until day 28. Nrl levels were low in ESC-derived populations compared with developing retinae. Transplantation of early stage retinal cultures produced large tumors, which were avoided by prolonged retinal differentiation (up to day 28) prior to transplantation. Integrated mature photoreceptors were not observed in the adult retina, even when more than 60% of transplanted ESC-derived cells expressed Crx. We conclude that exclusion of proliferative cells from ESC-derived cultures is essential for effective transplantation. Despite showing expression profiles characteristic of immature photoreceptors, the ESC-derived precursors generated using this protocol did not display transplantation competence equivalent to precursors from the postnatal retina.
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Affiliation(s)
- Emma L West
- Department of Genetics, UCL Institute of Ophthalmology, University College London, United Kingdom
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Eyes on DNA methylation: current evidence for DNA methylation in ocular development and disease. J Ocul Biol Dis Infor 2012; 4:95-103. [PMID: 23538551 DOI: 10.1007/s12177-012-9078-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 03/05/2012] [Indexed: 12/20/2022] Open
Abstract
Epigenetic modulation of chromatin states constitutes a vital component of the cellular repertoire of transcriptional regulatory mechanisms. The development of new technologies capable of generating genome-wide maps of chromatin modifications has re-energized the field. We are now poised to determine how species- and tissue-specific patterns of DNA methylation, in concert with other chromatin modifications, function to establish and maintain cell- and tissue-specific patterns of gene expression during normal development, cellular differentiation, and disease. This review addresses our current understanding of the major mechanisms and function of DNA methylation in vertebrates with a historical perspective and an emphasis on what is known about DNA methylation in eye development and disease.
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The rod photoreceptor lineage of teleost fish. Prog Retin Eye Res 2011; 30:395-404. [PMID: 21742053 DOI: 10.1016/j.preteyeres.2011.06.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 06/21/2011] [Accepted: 06/23/2011] [Indexed: 11/24/2022]
Abstract
The retinas of postembryonic teleost fish continue to grow for the lifetime of the fish. New retinal cells are added continuously at the retinal margin, by stem cells residing at the circumferential germinal zone. Some of these retinal cells differentiate as Müller glia with cell bodies that reside within the inner nuclear layer. These glia retain some stem cell properties in that they carry out asymmetric cell divisions and continuously generate a population of transit-amplifying cells--the rod photoreceptor lineage--that are committed to rod photoreceptor neurogenesis. These rod progenitors progress through a stereotyped sequence of changes in gene expression as they continue to divide and migrate to the outer nuclear layer. Now referred to as rod precursors, they undergo terminal mitoses and then differentiate as rods, which are inserted into the existing array of rod and cone photoreceptors. The rod lineage displays developmental plasticity, as rod precursors can respond to the loss of rods through increased proliferation, resulting in rod replacement. The stem cells of the rod lineage, Müller glia, respond to acute damage of other retinal cell types by increasing their rate of proliferation. In addition, the Müller glia in an acutely damaged retina dedifferentiate and become multipotent, generating new, functional neurons. This review focuses on the cells of the rod lineage and includes discussions of experiments over the last 30 years that led to their identification and characterization, and the discovery of the stem cells residing at the apex of the lineage. The plasticity of cells of the rod lineage, their relationships to cone progenitors, and the applications of this information for developing future treatments for human retinal disorders will also be discussed.
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