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Cen LP, Park KK, So KF. Optic nerve diseases and regeneration: How far are we from the promised land? Clin Exp Ophthalmol 2023; 51:627-641. [PMID: 37317890 PMCID: PMC10519420 DOI: 10.1111/ceo.14259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 05/10/2023] [Accepted: 05/18/2023] [Indexed: 06/16/2023]
Abstract
The retinal ganglion cells (RGCs) are the sole output neurons that connect information from the retina to the brain. Optic neuropathies such as glaucoma, trauma, inflammation, ischemia and hereditary optic neuropathy can cause RGC loss and axon damage, and lead to partial or total loss of vision, which is an irreversible process in mammals. The accurate diagnoses of optic neuropathies are crucial for timely treatments to prevent irrevocable RGCs loss. After severe ON damage in optic neuropathies, promoting RGC axon regeneration is vital for restoring vision. Clearance of neuronal debris, decreased intrinsic growth capacity, and the presence of inhibitory factors have been shown to contribute to the failure of post-traumatic CNS regeneration. Here, we review the current understanding of manifestations and treatments of various common optic neuropathies. We also summarise the current known mechanisms of RGC survival and axon regeneration in mammals, including specific intrinsic signalling pathways, key transcription factors, reprogramming genes, inflammation-related regeneration factors, stem cell therapy, and combination therapies. Significant differences in RGC subtypes in survival and regenerative capacity after injury have also been found. Finally, we highlight the developmental states and non-mammalian species that are capable of regenerating RGC axons after injury, and cellular state reprogramming for neural repair.
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Affiliation(s)
- Ling-Ping Cen
- Department of Neuro-Ophthalmology, Joint Shantou International Eye Centre of Shantou University and The Chinese University of Hong Kong, Shantou, Guangdong, China
- Shantou University Medical College, Shantou, Guangdong, China
| | - Kevin K. Park
- Department of Neurological Surgery, The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Kowk-Fai So
- Guangzhou-HongKong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, China
- Aier School of Ophthalmology, Changsha Aier Hospital of Ophthalmology, Changsha, China
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2
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Subramani M, Van Hook MJ, Ahmad I. Reproducible generation of human retinal ganglion cells from banked retinal progenitor cells: analysis of target recognition and IGF-1-mediated axon regeneration. Front Cell Dev Biol 2023; 11:1214104. [PMID: 37519299 PMCID: PMC10373790 DOI: 10.3389/fcell.2023.1214104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 06/26/2023] [Indexed: 08/01/2023] Open
Abstract
The selective degeneration of retinal ganglion cells (RGCs) is a common feature in glaucoma, a complex group of diseases, leading to irreversible vision loss. Stem cell-based glaucoma disease modeling, cell replacement, and axon regeneration are viable approaches to understand mechanisms underlying glaucomatous degeneration for neuroprotection, ex vivo stem cell therapy, and therapeutic regeneration. These approaches require direct and facile generation of human RGCs (hRGCs) from pluripotent stem cells. Here, we demonstrate a method for rapid generation of hRGCs from banked human pluripotent stem cell-derived retinal progenitor cells (hRPCs) by recapitulating the developmental mechanism. The resulting hRGCs are stable, functional, and transplantable and have the potential for target recognition, demonstrating their suitability for both ex vivo stem cell approaches to glaucomatous degeneration and disease modeling. Additionally, we demonstrate that hRGCs derived from banked hRPCs are capable of regenerating their axons through an evolutionarily conserved mechanism involving insulin-like growth factor 1 and the mTOR axis, demonstrating their potential to identify and characterize the underlying mechanism(s) that can be targeted for therapeutic regeneration.
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3
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Lear BP, Moore DL. Moving CNS axon growth and regeneration research into human model systems. Front Neurosci 2023; 17:1198041. [PMID: 37425013 PMCID: PMC10324669 DOI: 10.3389/fnins.2023.1198041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 05/25/2023] [Indexed: 07/11/2023] Open
Abstract
Axon regeneration is limited in the adult mammalian central nervous system (CNS) due to both intrinsic and extrinsic factors. Rodent studies have shown that developmental age can drive differences in intrinsic axon growth ability, such that embryonic rodent CNS neurons extend long axons while postnatal and adult CNS neurons do not. In recent decades, scientists have identified several intrinsic developmental regulators in rodents that modulate growth. However, whether this developmentally programmed decline in CNS axon growth is conserved in humans is not yet known. Until recently, there have been limited human neuronal model systems, and even fewer age-specific human models. Human in vitro models range from pluripotent stem cell-derived neurons to directly reprogrammed (transdifferentiated) neurons derived from human somatic cells. In this review, we discuss the advantages and disadvantages of each system, and how studying axon growth in human neurons can provide species-specific knowledge in the field of CNS axon regeneration with the goal of bridging basic science studies to clinical trials. Additionally, with the increased availability and quality of 'omics datasets of human cortical tissue across development and lifespan, scientists can mine these datasets for developmentally regulated pathways and genes. As there has been little research performed in human neurons to study modulators of axon growth, here we provide a summary of approaches to begin to shift the field of CNS axon growth and regeneration into human model systems to uncover novel drivers of axon growth.
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Affiliation(s)
| | - Darcie L. Moore
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, United States
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4
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Maiese K. Cellular Metabolism: A Fundamental Component of Degeneration in the Nervous System. Biomolecules 2023; 13:816. [PMID: 37238686 PMCID: PMC10216724 DOI: 10.3390/biom13050816] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 05/05/2023] [Accepted: 05/10/2023] [Indexed: 05/28/2023] Open
Abstract
It is estimated that, at minimum, 500 million individuals suffer from cellular metabolic dysfunction, such as diabetes mellitus (DM), throughout the world. Even more concerning is the knowledge that metabolic disease is intimately tied to neurodegenerative disorders, affecting both the central and peripheral nervous systems as well as leading to dementia, the seventh leading cause of death. New and innovative therapeutic strategies that address cellular metabolism, apoptosis, autophagy, and pyroptosis, the mechanistic target of rapamycin (mTOR), AMP activated protein kinase (AMPK), growth factor signaling with erythropoietin (EPO), and risk factors such as the apolipoprotein E (APOE-ε4) gene and coronavirus disease 2019 (COVID-19) can offer valuable insights for the clinical care and treatment of neurodegenerative disorders impacted by cellular metabolic disease. Critical insight into and modulation of these complex pathways are required since mTOR signaling pathways, such as AMPK activation, can improve memory retention in Alzheimer's disease (AD) and DM, promote healthy aging, facilitate clearance of β-amyloid (Aß) and tau in the brain, and control inflammation, but also may lead to cognitive loss and long-COVID syndrome through mechanisms that can include oxidative stress, mitochondrial dysfunction, cytokine release, and APOE-ε4 if pathways such as autophagy and other mechanisms of programmed cell death are left unchecked.
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Affiliation(s)
- Kenneth Maiese
- Cellular and Molecular Signaling, New York, NY 10022, USA
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5
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Zhang X, Xia M, Wu Y, Zhang F. Branched-Chain Amino Acids Metabolism and Their Roles in Retinopathy: From Relevance to Mechanism. Nutrients 2023; 15:2161. [PMID: 37432261 DOI: 10.3390/nu15092161] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Revised: 04/20/2023] [Accepted: 04/27/2023] [Indexed: 07/12/2023] Open
Abstract
Retinopathy is one of the leading causes of irreversible blindness and vision loss worldwide. Imbalanced nutrients play important roles in the pathogenesis and pathophysiology of retinal diseases. Branched-Chain Amino Acids (BCAAs), as essential amino acids, perform a variety of biological functions, including protein synthesis, glucose metabolism, lipid metabolism, inflammation, and oxidative stress in metabolic tissues of diabetes and aging-related diseases. Recently, it has been shown that BCAAs are highly related to neuroprotection, oxidative stress, inflammatory and glutamate toxicity in the retina of retinopathy. Therefore, this review summarizes the alterations of BCAA levels in retinopathy, especially diabetic retinopathy and aging-related macular disease, and the genetics, functions, and mechanisms of BCAAs in the retina as well as other metabolic tissues for reference. All of these efforts aim to provide fundamental knowledge of BCAAs for further discoveries and research on retina health based on the sensing and signaling of essential amino acids.
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Affiliation(s)
- Xiaonan Zhang
- National Clinical Research Center for Eye Diseases, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
- Liaoning Provence Key Laboratory of Genome Engineered Animal Models, National Center of Genetically Engineered Animal Models for International Research, Institute for Genome Engineered Animal Models of Human Diseases, Dalian Medical University, Dalian 116000, China
- Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai 200080, China
| | - Mengxue Xia
- National Clinical Research Center for Eye Diseases, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
- Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai 200080, China
| | - Yingjie Wu
- Liaoning Provence Key Laboratory of Genome Engineered Animal Models, National Center of Genetically Engineered Animal Models for International Research, Institute for Genome Engineered Animal Models of Human Diseases, Dalian Medical University, Dalian 116000, China
- Shandong Provincial Hospital, School of Laboratory Animal & Shandong Laboratory Animal Center, Science and Technology Innovation Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan 250021, China
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY 10010, USA
| | - Fang Zhang
- National Clinical Research Center for Eye Diseases, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
- Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai 200080, China
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6
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Boal AM, McGrady NR, Chamling X, Kagitapalli BS, Zack DJ, Calkins DJ, Risner ML. Microfluidic Platforms Promote Polarization of Human-Derived Retinal Ganglion Cells That Model Axonopathy. Transl Vis Sci Technol 2023; 12:1. [PMID: 37010860 PMCID: PMC10080917 DOI: 10.1167/tvst.12.4.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 03/09/2023] [Indexed: 04/04/2023] Open
Abstract
Purpose Axons depend on long-range transport of proteins and organelles which increases susceptibility to metabolic stress in disease. The axon initial segment (AIS) is particularly vulnerable due to the high bioenergetic demand of action potential generation. Here, we prepared retinal ganglion cells derived from human embryonic stem cells (hRGCs) to probe how axonal stress alters AIS morphology. Methods hRGCs were cultured on coverslips or microfluidic platforms. We assayed AIS specification and morphology by immunolabeling against ankyrin G (ankG), an axon-specific protein, and postsynaptic density 95 (PSD-95), a dendrite-specific protein. Using microfluidic platforms that enable fluidic isolation, we added colchicine to the axon compartment to lesion axons. We verified axonopathy by measuring the anterograde axon transport of cholera toxin subunit B and immunolabeling against cleaved caspase 3 (CC3) and phosphorylated neurofilament H (SMI-34). We determined the influence of axon injury on AIS morphology by immunolabeling samples against ankG and measuring AIS distance from soma and length. Results Based on measurements of ankG and PSD-95 immunolabeling, microfluidic platforms promote the formation and separation of distinct somatic-dendritic versus axonal compartments in hRGCs compared to coverslip cultures. Chemical lesioning of axons by colchicine reduced hRGC anterograde axon transport, increased varicosity density, and enhanced expression of CC3 and SMI-34. Interestingly, we found that colchicine selectively affected hRGCs with axon-carrying dendrites by reducing AIS distance from somas and increasing length, thus suggesting reduced capacity to maintain excitability. Conclusions Thus, microfluidic platforms promote polarized hRGCs that enable modeling of axonopathy. Translational Relevance Microfluidic platforms may be used to assay compartmentalized degeneration that occurs during glaucoma.
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Affiliation(s)
- Andrew M. Boal
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Nolan R. McGrady
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Xitiz Chamling
- Wilmer Eye Institute, Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Bhanu S. Kagitapalli
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Donald J. Zack
- Wilmer Eye Institute, Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - David J. Calkins
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Michael L. Risner
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
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7
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Subramani M, Hook MV, Rajamoorthy M, Qiu F, Ahmad I. Human Retinal Ganglion Cells Respond to Evolutionarily Conserved Chemotropic Cues for Intra Retinal Guidance and Regeneration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.01.526677. [PMID: 36778442 PMCID: PMC9915675 DOI: 10.1101/2023.02.01.526677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Retinal ganglion cells (RGCs) connect the retina with the higher centers in the brain for visual perception. Their degeneration leads to irreversible vision loss in glaucoma patients. Since human RGCs (hRGCs) are born during fetal development and connections with the central targets are established before birth, the mechanism underlying their axon growth and guidance remains poorly understood. Here, using RGCs directly generated from human embryonic stem cells, we demonstrate that hRGCs express a battery of guidance receptors. These receptors allow hRGCs to read the spatially arrayed chemotropic cues in the developing rat retina for the centripetal orientation of axons toward the optic disc, suggesting that the mechanism of intra-retinal guidance is conserved in hRGCs. The centripetal orientation of hRGCs axons is not only in response to chemo-repulsion but also involves chemo-attraction, mediated by Netrin-1/DCC interactions. The spatially arrayed chemotropic cues differentially influence hRGCs physiological responses, suggesting that neural activity of hRGCs may facilitate axon growth during inter-retinal guidance. Additionally, we demonstrate that Netrin-1/DCC interactions, besides promoting axon growth, facilitate hRGCs axon regeneration by recruiting the mTOR signaling pathway. The diverse influence of Netrin-1/DCC interactions ranging from axon growth to regeneration may involve recruitment of multiple intracellular signaling pathways as revealed by transcriptome analysis of hRGCs. From the perspective of ex-vivo stem cell approach to glaucomatous degeneration, our findings posit that ex-vivo generated human RGCs are capable of reading the intra-retinal cues for guidance toward the optic disc, the first step toward connecting with the central target to restore vision.
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8
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Huang KC, Gomes C, Shiga Y, Belforte N, VanderWall KB, Lavekar SS, Fligor CM, Harkin J, Di Polo A, Meyer JS. Autophagy disruption reduces mTORC1 activation leading to retinal ganglion cell neurodegeneration associated with glaucoma. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.04.522687. [PMID: 36711831 PMCID: PMC9881969 DOI: 10.1101/2023.01.04.522687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Autophagy dysfunction has been associated with several neurodegenerative diseases including glaucoma, characterized by the degeneration of retinal ganglion cells (RGCs). However, the mechanisms by which autophagy dysfunction promotes RGC damage remain unclear. Here, we hypothesized that perturbation of the autophagy pathway results in increased autophagic demand, thereby downregulating signaling through mammalian target of rapamycin complex 1 (mTORC1), a negative regulator of autophagy, contributing to the degeneration of RGCs. We identified an impairment of autophagic-lysosomal degradation and decreased mTORC1 signaling via activation of the stress sensor adenosine monophosphate-activated protein kinase (AMPK), along with subsequent neurodegeneration in RGCs differentiated from human pluripotent stem cells (hPSCs) with a glaucoma-associated variant of Optineurin (OPTN-E50K). Similarly, the microbead occlusion model of glaucoma resulting in ocular hypertension also exhibited autophagy disruption and mTORC1 downregulation. Pharmacological inhibition of mTORC1 in hPSC-derived RGCs recapitulated disease-related neurodegenerative phenotypes in otherwise healthy RGCs, while the mTOR-independent induction of autophagy reduced protein accumulation and restored neurite outgrowth in diseased OPTN-E50K RGCs. Taken together, these results highlight an important balance between autophagy and mTORC1 signaling essential for RGC homeostasis, while disruption to these pathways contributes to neurodegenerative features in glaucoma, providing a potential therapeutic target to prevent neurodegeneration.
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Affiliation(s)
- Kang-Chieh Huang
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis IN USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis IN USA
| | - Cátia Gomes
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis IN USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis IN USA
| | - Yukihiro Shiga
- Department of Neuroscience, University of Montreal, Montreal, Quebec, Canada
- University of Montreal Hospital Research Centre, Montreal, Quebec, Canada
| | - Nicolas Belforte
- Department of Neuroscience, University of Montreal, Montreal, Quebec, Canada
- University of Montreal Hospital Research Centre, Montreal, Quebec, Canada
| | - Kirstin B. VanderWall
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis IN USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis IN USA
| | - Sailee S. Lavekar
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis IN USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis IN USA
| | - Clarisse M. Fligor
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis IN USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis IN USA
| | - Jade Harkin
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis IN USA
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis IN USA
| | - Adriana Di Polo
- Department of Neuroscience, University of Montreal, Montreal, Quebec, Canada
- University of Montreal Hospital Research Centre, Montreal, Quebec, Canada
| | - Jason S. Meyer
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis IN USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis IN USA
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis IN USA
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis IN USA
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9
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Huang KC, Gomes C, Meyer JS. Retinal Ganglion Cells in a Dish: Current Strategies and Recommended Best Practices for Effective In Vitro Modeling of Development and Disease. Handb Exp Pharmacol 2023; 281:83-102. [PMID: 36907969 PMCID: PMC10497719 DOI: 10.1007/164_2023_642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
Abstract
The ability to derive retinal ganglion cells (RGCs) from human pluripotent stem cells (hPSCs) provides an extraordinary opportunity to study the development of RGCs as well as cellular mechanisms underlying their degeneration in optic neuropathies. In the past several years, multiple approaches have been established that allow for the generation of RGCs from hPSCs, with these methods greatly improved in more recent studies to yield mature RGCs that more faithfully recapitulate phenotypes within the eye. Nevertheless, numerous differences still remain between hPSC-RGCs and those found within the human eye, with these differences likely explained at least in part due to the environment in which hPSC-RGCs are grown. With the ultimate goal of generating hPSC-RGCs that most closely resemble those within the retina for proper studies of retinal development, disease modeling, as well as cellular replacement, we review within this manuscript the current effective approaches for the differentiation of hPSC-RGCs, as well as how they have been applied for the investigation of RGC neurodegenerative diseases such as glaucoma. Furthermore, we provide our opinions on the characteristics of RGCs necessary for their use as effective in vitro disease models and importantly, how these current systems should be improved to more accurately reflect disease states. The establishment of characteristics in differentiated hPSC-RGCs that more effectively mimic RGCs within the retina will not only enable their use as effective models of RGC development, but will also create a better disease model for the identification of mechanisms underlying the neurodegeneration of RGCs in disease states such as glaucoma, further facilitating the development of therapeutic approaches to rescue RGCs from degeneration in disease states.
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Affiliation(s)
- Kang-Chieh Huang
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN, USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Cátia Gomes
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Jason S Meyer
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA.
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA.
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA.
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA.
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10
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Ahmad I, Subramani M. Microglia: Friends or Foes in Glaucoma? A Developmental Perspective. Stem Cells Transl Med 2022; 11:1210-1218. [PMID: 36426733 PMCID: PMC9801300 DOI: 10.1093/stcltm/szac077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 09/29/2022] [Indexed: 11/27/2022] Open
Abstract
Glaucoma is the most prevalent form of optic neuropathy where a progressive degeneration of retinal ganglion cells (RGCs) leads to irreversible loss of vision. The mechanism underlying glaucomatous degeneration remains poorly understood. However, evidence suggests that microglia, which regulate RGC numbers and synaptic integrity during development and provide homeostatic support in adults, may contribute to the disease process. Hence, microglia represent a valid cellular target for therapeutic approaches in glaucoma. Here, we provide an overview of the role of microglia in RGC development and degeneration in the backdrop of neurogenesis and neurodegeneration in the central nervous system and discuss how pathological recapitulation of microglia-mediated developmental mechanisms may help initiate or exacerbate glaucomatous degeneration.
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Affiliation(s)
- Iqbal Ahmad
- Corresponding author: Iqbal Ahmad, Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE 68198, USA.
| | - Murali Subramani
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA
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11
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Hanyuda A, Rosner BA, Wiggs JL, Willett WC, Tsubota K, Pasquale LR, Kang JH. Prospective study of dietary intake of branched-chain amino acids and the risk of primary open-angle glaucoma. Acta Ophthalmol 2022; 100:e760-e769. [PMID: 34240564 DOI: 10.1111/aos.14971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 06/17/2021] [Indexed: 11/27/2022]
Abstract
PURPOSE Metabolomic and preclinical studies suggest that branched-chain amino acids (BCAA) may be inversely associated with neurodegenerative diseases including glaucoma. We therefore assessed the long-term association between dietary intake of BCAA and incident primary open-angle glaucoma (POAG) and POAG subtypes. METHODS We followed biennially participants of the Nurses' Health Study (NHS; 65 531 women: 1984-2016), Health Professionals Follow-up Study (42 254 men: 1986-2016) and NHSII (66 904 women; 1991-2017). Eligible participants were 40+ years old and reported eye examinations. Repeated validated food frequency questionnaires were used to assess dietary intake of BCAA. Incident cases of POAG and POAG subtypes defined by visual field (VF) loss and untreated intraocular pressure (IOP) were confirmed by medical record review. Multivariable-adjusted relative risks (MVRRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models. RESULTS We identified 1946 incident POAG cases. The pooled MVRRs of POAG for the highest quintile (Q5 = 17.1 g/day) versus lowest quintile (Q1 = 11.2 g/day) of total BCAA intake was 0.93 (95% CI, 0.73-1.19; ptrend = 0.45; pheterogeneity by sex = 0.24). For subtypes of POAG defined by IOP level or POAG with only peripheral VF loss, no associations were observed for men or women (ptrend ≥ 0.20); however, for the POAG subtype with early paracentral VF loss, there was a suggestion of an inverse association in women (MVRRQ5versusQ1 = 0.80 [95% CI, 0.57-1.12; ptrend = 0.12]) but not in men (MVRRQ5versusQ1 = 1.38 [95% CI, 0.81-2.34; ptrend = 0.28; pheterogeneity by sex = 0.06]). CONCLUSION Higher dietary intake of BCAA was not associated with POAG risk.
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Affiliation(s)
- Akiko Hanyuda
- Department of Nutrition Harvard T.H. Chan School of Public Health Boston Massachusetts USA
- Department of Ophthalmology Keio University School of Medicine Tokyo Japan
- Epidemiology and Prevention Group Center for Public Health Sciences National Cancer Center Tokyo Japan
| | - Bernard A. Rosner
- Department of Biostatistics Harvard T.H. Chan School of Public Health Boston Massachusetts USA
- Channing Division of Network Medicine Department of Medicine Brigham and Women’s Hospital Harvard Medical School Boston Massachusetts USA
| | - Janey L. Wiggs
- Department of Ophthalmology Harvard Medical School Massachusetts Eye and Ear Boston Massachusetts USA
| | - Walter C. Willett
- Department of Nutrition Harvard T.H. Chan School of Public Health Boston Massachusetts USA
- Channing Division of Network Medicine Department of Medicine Brigham and Women’s Hospital Harvard Medical School Boston Massachusetts USA
- Department of Epidemiology Harvard T.H. Chan School of Public Health Boston Massachusetts USA
| | - Kazuo Tsubota
- Department of Ophthalmology Keio University School of Medicine Tokyo Japan
| | - Louis R. Pasquale
- Channing Division of Network Medicine Department of Medicine Brigham and Women’s Hospital Harvard Medical School Boston Massachusetts USA
- Department of Ophthalmology Icahn School of Medicine at Mount Sinai New York New York USA
| | - Jae H. Kang
- Channing Division of Network Medicine Department of Medicine Brigham and Women’s Hospital Harvard Medical School Boston Massachusetts USA
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12
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Boccuni I, Fairless R. Retinal Glutamate Neurotransmission: From Physiology to Pathophysiological Mechanisms of Retinal Ganglion Cell Degeneration. Life (Basel) 2022; 12:638. [PMID: 35629305 PMCID: PMC9147752 DOI: 10.3390/life12050638] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 04/22/2022] [Accepted: 04/22/2022] [Indexed: 12/12/2022] Open
Abstract
Glutamate neurotransmission and metabolism are finely modulated by the retinal network, where the efficient processing of visual information is shaped by the differential distribution and composition of glutamate receptors and transporters. However, disturbances in glutamate homeostasis can result in glutamate excitotoxicity, a major initiating factor of common neurodegenerative diseases. Within the retina, glutamate excitotoxicity can impair visual transmission by initiating degeneration of neuronal populations, including retinal ganglion cells (RGCs). The vulnerability of RGCs is observed not just as a result of retinal diseases but has also been ascribed to other common neurodegenerative and peripheral diseases. In this review, we describe the vulnerability of RGCs to glutamate excitotoxicity and the contribution of different glutamate receptors and transporters to this. In particular, we focus on the N-methyl-d-aspartate (NMDA) receptor as the major effector of glutamate-induced mechanisms of neurodegeneration, including impairment of calcium homeostasis, changes in gene expression and signalling, and mitochondrial dysfunction, as well as the role of endoplasmic reticular stress. Due to recent developments in the search for modulators of NMDA receptor signalling, novel neuroprotective strategies may be on the horizon.
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Affiliation(s)
- Isabella Boccuni
- Institute for Physiology and Pathophysiology, Heidelberg University, 69120 Heidelberg, Germany
- Department of Neurology, University Clinic Heidelberg, 69120 Heidelberg, Germany;
| | - Richard Fairless
- Department of Neurology, University Clinic Heidelberg, 69120 Heidelberg, Germany;
- Clinical Cooperation Unit (CCU) Neurooncology, German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
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13
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A Review on Microfluidic Platforms Applied to Nerve Regeneration. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12073534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In recent decades, microfluidics have significantly advanced nerve regeneration research. Microfluidic devices can provide an accurate simulation of in vivo microenvironment for different research purposes such as analyzing myelin growth inhibitory factors, screening drugs, assessing nerve growth factors, and exploring mechanisms of neural injury and regeneration. The microfluidic platform offers technical supports for nerve regeneration that enable precise spatio-temporal control of cells, such as neuron isolation, single-cell manipulation, neural patterning, and axon guidance. In this paper, we review the development and recent advances of microfluidic platforms for nerve regeneration research.
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Lu F, Leach LL, Gross JM. mTOR activity is essential for retinal pigment epithelium regeneration in zebrafish. PLoS Genet 2022; 18:e1009628. [PMID: 35271573 PMCID: PMC8939802 DOI: 10.1371/journal.pgen.1009628] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 03/22/2022] [Accepted: 02/23/2022] [Indexed: 12/30/2022] Open
Abstract
The retinal pigment epithelium (RPE) plays numerous critical roles in maintaining vision and this is underscored by the prevalence of degenerative blinding diseases like age-related macular degeneration (AMD), in which visual impairment is caused by progressive loss of RPE cells. In contrast to mammals, zebrafish possess the ability to intrinsically regenerate a functional RPE layer after severe injury. The molecular underpinnings of this regenerative process remain largely unknown yet hold tremendous potential for developing treatment strategies to stimulate endogenous regeneration in the human eye. In this study, we demonstrate that the mTOR pathway is activated in RPE cells post-genetic ablation. Pharmacological and genetic inhibition of mTOR activity impaired RPE regeneration, while mTOR activation enhanced RPE recovery post-injury, demonstrating that mTOR activity is essential for RPE regeneration in zebrafish. RNA-seq of RPE isolated from mTOR-inhibited larvae identified a number of genes and pathways dependent on mTOR activity at early and late stages of regeneration; amongst these were components of the immune system, which is emerging as a key regulator of regenerative responses across various tissue and model systems. Our results identify crosstalk between macrophages/microglia and the RPE, wherein mTOR activity is required for recruitment of macrophages/microglia to the RPE injury site. Macrophages/microglia then reinforce mTOR activity in regenerating RPE cells. Interestingly, the function of macrophages/microglia in maintaining mTOR activity in the RPE appeared to be inflammation-independent. Taken together, these data identify mTOR activity as a key regulator of RPE regeneration and link the mTOR pathway to immune responses in facilitating RPE regeneration.
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Affiliation(s)
- Fangfang Lu
- Department of Ophthalmology, Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Lyndsay L. Leach
- Department of Ophthalmology, Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Jeffrey M. Gross
- Department of Ophthalmology, Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
- * E-mail:
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15
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Lee SH, Han JW, Yang JY, Jun HO, Bang JH, Shin H, Choi JH, Lee J, Madrakhimov SB, Chung KH, Chang HS, Lyu J, Park TK. Role of mTORC1 activity during early retinal development and lamination in human-induced pluripotent stem cell-derived retinal organoids. Cell Death Dis 2022; 8:56. [PMID: 35136019 PMCID: PMC8826382 DOI: 10.1038/s41420-022-00837-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 12/14/2021] [Accepted: 01/13/2022] [Indexed: 11/09/2022]
Abstract
Retinal organoids derived from human-induced pluripotent stem cells (hiPSC) are powerful tools for studying retinal development as they model spatial and temporal differentiation of retinal cell types. Vertebrate retinal development involves a delicate and coordinated process of retinal progenitor cell (RPC) differentiation, and the mammalian target of rapamycin complex 1 (mTORC1) has been reported to play a significant role in this complex process. Herein, using hiPSC-derived retinal organoids, we identify the time-dependent role of mTORC1 in retinal development, specifically in retinal ganglion cell (RGC) differentiation and the retinal lamination process, during the early stages of retinal organoid (RO) development. mTORC1 activity in ROs was the highest at 40 days of differentiation. MHY1485-induced hyperactivation of mTORC1 during this period resulted in a significant increase in the overall size of ROs compared to the untreated controls and rapamycin-treated Ros; there was also a marked increase in proliferative activity within the inner and outer layers of ROs. Moreover, the MHY1485-treated ROs showed a significant increase in the number of ectopic RGCs in the outer layers (indicating disruption of retinal laminar structure), with robust expression of HuC/D-binding proteins in the inner layers. These results demonstrate that mTORC1 plays a critical role in the development of hiPSC-derived ROs, especially during the early stages of differentiation.
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Affiliation(s)
- Si Hyung Lee
- Department of Ophthalmology, College of Medicine, Soonchunhyang University, Cheonan, Republic of Korea.,Department of Ophthalmology, Soonchunhyang University Hospital Bucheon, Bucheon, Republic of Korea
| | - Jung Woo Han
- Department of Ophthalmology, Soonchunhyang University Hospital Bucheon, Bucheon, Republic of Korea.,Laboratory of Molecular Therapy for Retinal Degeneration, Hyangseol Medical Research Institute, Soonchunhyang University Hospital Bucheon, Bucheon, Republic of Korea
| | - Jin Young Yang
- Laboratory of Molecular Therapy for Retinal Degeneration, Hyangseol Medical Research Institute, Soonchunhyang University Hospital Bucheon, Bucheon, Republic of Korea.,Department of Interdisciplinary Program in Biomedical Science, Soonchunhyang University, Graduate School, Bucheon Hospital, Bucheon, Republic of Korea
| | - Hyoung Oh Jun
- Laboratory of Molecular Therapy for Retinal Degeneration, Hyangseol Medical Research Institute, Soonchunhyang University Hospital Bucheon, Bucheon, Republic of Korea
| | - Ji Hong Bang
- Laboratory of Molecular Therapy for Retinal Degeneration, Hyangseol Medical Research Institute, Soonchunhyang University Hospital Bucheon, Bucheon, Republic of Korea.,Department of Interdisciplinary Program in Biomedical Science, Soonchunhyang University, Graduate School, Bucheon Hospital, Bucheon, Republic of Korea
| | - Heejeong Shin
- Laboratory of Molecular Therapy for Retinal Degeneration, Hyangseol Medical Research Institute, Soonchunhyang University Hospital Bucheon, Bucheon, Republic of Korea.,Department of Interdisciplinary Program in Biomedical Science, Soonchunhyang University, Graduate School, Bucheon Hospital, Bucheon, Republic of Korea
| | - Ji Hye Choi
- Laboratory of Molecular Therapy for Retinal Degeneration, Hyangseol Medical Research Institute, Soonchunhyang University Hospital Bucheon, Bucheon, Republic of Korea
| | - Jongwoo Lee
- Department of Biological Sciences, Sungkyunkwan University, Suwon, Republic of Korea
| | | | - Kyung Hwun Chung
- Laboratory of Molecular Therapy for Retinal Degeneration, Hyangseol Medical Research Institute, Soonchunhyang University Hospital Bucheon, Bucheon, Republic of Korea
| | - Hun Soo Chang
- Department of Anatomy and BK21 Four Project, College of Medicine, Soonchunhyang University, Cheonan, Republic of Korea
| | - Jungmook Lyu
- Department of Medical Science, Konyang University, Daejun, Republic of Korea
| | - Tae Kwann Park
- Department of Ophthalmology, College of Medicine, Soonchunhyang University, Cheonan, Republic of Korea. .,Department of Ophthalmology, Soonchunhyang University Hospital Bucheon, Bucheon, Republic of Korea. .,Laboratory of Molecular Therapy for Retinal Degeneration, Hyangseol Medical Research Institute, Soonchunhyang University Hospital Bucheon, Bucheon, Republic of Korea. .,Department of Interdisciplinary Program in Biomedical Science, Soonchunhyang University, Graduate School, Bucheon Hospital, Bucheon, Republic of Korea. .,Ex Lumina Therapeutics and Technologies, Inc, Bucheon, Republic of Korea.
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16
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It is time for a moonshot to find “Cures” for diabetic retinal disease. Prog Retin Eye Res 2022; 90:101051. [DOI: 10.1016/j.preteyeres.2022.101051] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 01/19/2022] [Accepted: 01/31/2022] [Indexed: 12/13/2022]
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Guo J, Liu H, Fu L. MicroRNA-124 ameliorates autophagic dysregulation in glaucoma via regulation of P2X7-mediated Akt/mTOR signaling. Cutan Ocul Toxicol 2021; 41:43-48. [PMID: 34844494 DOI: 10.1080/15569527.2021.2003378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Glaucoma is a neurodegenerative disease that leads to irrevocable blindness. In glaucoma, even though axonal damage and function deficit culminates in retinal ganglion cell (RGC) degeneration, our knowledge on the autophagic mechanisms and the role of specific microRNAs is still limited. In this study, we investigated the role of microRNA-124 (MiR-124) in surgically induced glaucomatous neurodegeneration using a mouse model. Animals were segregated into four cohorts of 10 each: (i) sham-operated (n = 10); (ii) surgically induced glaucoma (SIG; n = 10); (iii) SIG + miR-124 mimic; (iv) SIG + miR-NC. Chronic elevation of intraocular pressure (IOP) is a critical risk factor for glaucoma. In our study, chronically elevated IOP caused anterograde axonal transport (AAT) defect, increased the autophagic activity (manifested by significantly (p < 0.05) increased LC3-II/LC3-I ratio, beclin-1 and Atg7 protein expressions) and also downmodulated the protein expression of p-Akt and p-mTOR, mediated by the purinergic P2 receptor subtype 7 (P2X7) upmodulation-leading to retinal degeneration. However, administration of miR-124 mimic improved the retinal integrity and function, as indicated by the improved AAT function, normalized the autophagic dysfunction, modulated the protein expression of P2X7-mediated p-Akt and p-mTOR. Hence, we propose that development of miR-124-based advanced therapies might be a potential avenue in the treatment of glaucomatous neurodegeneration.
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Affiliation(s)
- Jun Guo
- Department of Ophthalmology, Zhongshan Hospital Affiliated with Dalian University, Dalian, China
| | - Haojie Liu
- Department of Ophthalmology, Zhongshan Hospital Affiliated with Dalian University, Dalian, China
| | - Lin Fu
- Department of Ophthalmology, Zhongshan Hospital Affiliated with Dalian University, Dalian, China
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Lukomska A, Kim J, Rheaume BA, Xing J, Hoyt A, Lecky E, Steidl T, Trakhtenberg EF. Developmentally upregulated transcriptional elongation factor a like 3 suppresses axon regeneration after optic nerve injury. Neurosci Lett 2021; 765:136260. [PMID: 34560191 PMCID: PMC8572158 DOI: 10.1016/j.neulet.2021.136260] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 09/04/2021] [Accepted: 09/19/2021] [Indexed: 11/24/2022]
Abstract
Projection neurons of the mammalian central nervous system (CNS) do not spontaneously regenerate axons which have been damaged by an injury or disease, often leaving patients with permanent disabilities that affect motor, cognitive, or sensory functions. Although several molecular targets which promote some extent of axon regeneration in animal models have been identified, the resulting recovery is very limited, and the molecular mechanisms underlying the axonal regenerative failure in the CNS are still poorly understood. One of the most studied targets for axon regeneration in the CNS is the mTOR pathway. A number of developmentally regulated genes also have been found to play a role in CNS axon regeneration. Here, we found that Transcriptional Elongation Factor A Like 3 (Tceal3), belonging to the Bex/Tceal transcriptional regulator family, which also modulates the mTOR pathway, is developmentally upregulated in retinal ganglion cell (RGCs) projection CNS neurons, and suppresses their capacity to regenerate axons after injury.
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Affiliation(s)
- Agnieszka Lukomska
- Department of Neuroscience, University of Connecticut School of Medicine, 263 Farmington Ave., Farmington, CT 06030, USA
| | - Juhwan Kim
- Department of Neuroscience, University of Connecticut School of Medicine, 263 Farmington Ave., Farmington, CT 06030, USA
| | - Bruce A Rheaume
- Department of Neuroscience, University of Connecticut School of Medicine, 263 Farmington Ave., Farmington, CT 06030, USA
| | - Jian Xing
- Department of Neuroscience, University of Connecticut School of Medicine, 263 Farmington Ave., Farmington, CT 06030, USA
| | - Alexela Hoyt
- Department of Neuroscience, University of Connecticut School of Medicine, 263 Farmington Ave., Farmington, CT 06030, USA
| | - Emmalyn Lecky
- Department of Neuroscience, University of Connecticut School of Medicine, 263 Farmington Ave., Farmington, CT 06030, USA
| | - Tyler Steidl
- Department of Neuroscience, University of Connecticut School of Medicine, 263 Farmington Ave., Farmington, CT 06030, USA
| | - Ephraim F Trakhtenberg
- Department of Neuroscience, University of Connecticut School of Medicine, 263 Farmington Ave., Farmington, CT 06030, USA.
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mTORC1 Activation in Chx10-Specific Tsc1 Knockout Mice Accelerates Retina Aging and Degeneration. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:6715758. [PMID: 34777691 PMCID: PMC8589503 DOI: 10.1155/2021/6715758] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Revised: 10/14/2021] [Accepted: 10/25/2021] [Indexed: 11/23/2022]
Abstract
Age-associated decline in retina function is largely responsible for the irreversible vision deterioration in the elderly population. It is also an important risk factor for the development of degenerative and angiogenic diseases. However, the molecular mechanisms involved in the process of aging in the retina remain largely elusive. This study investigated the role of mTORC1 signaling in aging of the retina. We showed that mTORC1 was activated in old-aged retina, particularly in the ganglion cells. The role of mTORC1 activation was further investigated in Chx10-Cre;Tsc1fx/fx mouse (Tsc1-cKO). Activation of mTORC1 was found in bipolar and some of the ganglion and amacrine cells in the adult Tsc1-cKO retina. Bipolar cell hypertrophy and Müller gliosis were observed in Tsc1-cKO since 6 weeks of age. The abnormal endings of bipolar cell dendritic tips at the outer nuclear layer resembled that of the old-aged mice. Microglial cell activation became evident in 6-week-old Tsc1-cKO. At 5 months, the Tsc1-cKO mice exhibited advanced features of old-aged retina, including the expression of p16Ink4a and p21, expression of SA-β-gal in ganglion cells, decreased photoreceptor cell numbers, decreased electroretinogram responses, increased oxidative stress, microglial cell activation, and increased expression of immune and inflammatory genes. Inhibition of microglial cells by minocycline partially prevented photoreceptor cell loss and restored the electroretinogram responses. Collectively, our study showed that the activation of mTORC1 signaling accelerated aging of the retina by both cell autonomous and nonautonomous mechanisms. Our study also highlighted the role of microglia cells in driving the decline in retina function.
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Wu YR, Hashiguchi T, Sho J, Chiou SH, Takahashi M, Mandai M. Transplanted Mouse Embryonic Stem Cell-Derived Retinal Ganglion Cells Integrate and Form Synapses in a Retinal Ganglion Cell-Depleted Mouse Model. Invest Ophthalmol Vis Sci 2021; 62:26. [PMID: 34705025 PMCID: PMC8556558 DOI: 10.1167/iovs.62.13.26] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Purpose Retinal ganglion cell (RGC) transplantation is a therapeutic approach to replace irreversibly degenerated RGCs in diseases such as glaucoma. However, the application of primary RGCs is limited by the availability of tissues. The goal of this study was to evaluate whether transplanted mouse embryonic stem cell (mESC)-derived RGCs can integrate into the host retina and form cell connectivity with host cells. Methods In this study, we prepared small retinal fragments containing RGC as THY1-enhanced green fluorescent protein (EGFP)+ cells from mESCs and placed them near the retinal surface in the air-injected mouse eyes with or without N-methyl-d-aspartate (NMDA)-induced RGC depletion. After transplantation, THY1-EGFP+ cell integration was observed in whole-mounts and with immunostaining for synaptic markers. Results Transplanted THY1-EGFP+ cells survived for 12 weeks and extended neurites into the inner plexiform layer (IPL) of the host retina. Presumptive synapse formation was identified between grafted RGCs and host bipolar cells. The ratio of transplanted eyes with integration of THY1-EGFP+ neurites in the host IPL was higher in RGC-injured mice compared with healthy controls. Conclusions This report shows the potential for therapeutic use of pluripotent cell–derived RGCs by grafting the cells in healthy conditions and with an appropriate technical approach.
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Affiliation(s)
- You-Ren Wu
- Laboratory for Retinal Regeneration, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan.,Institute of Pharmacology, School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Tomoyo Hashiguchi
- Laboratory for Retinal Regeneration, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
| | - Junki Sho
- Laboratory for Retinal Regeneration, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
| | - Shih-Hwa Chiou
- Institute of Pharmacology, School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Masayo Takahashi
- Laboratory for Retinal Regeneration, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan.,Vision Care Cell Therapy, Inc., Kobe, Japan
| | - Michiko Mandai
- Laboratory for Retinal Regeneration, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
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21
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Risner ML, Pasini S, Chamling X, McGrady NR, Goldberg JL, Zack DJ, Calkins DJ. Intrinsic Morphologic and Physiologic Development of Human Derived Retinal Ganglion Cells In Vitro. Transl Vis Sci Technol 2021; 10:1. [PMID: 34383881 PMCID: PMC8362626 DOI: 10.1167/tvst.10.10.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Purpose Human retinal ganglion cells (hRGC) derived from human pluripotent stem cells are promising candidates to model, protect, and replace degenerating RGCs. Here, we examined intrinsic morphologic and physiologic development of hRGCs. Methods We used CRISPR-Cas9 to selectively express tdTomato under the RGC-specific promoter, BRN3B. Human pluripotent stem cells were chemically differentiated into hRGCs and cultured up to 7 weeks. We measured soma area, neurite complexity, synaptic protein, axon-related messenger RNA and protein, and voltage-dependent responses. Results Soma area, neurite complexity, and postsynaptic density protein 95 increased over time. Soma area and neurite complexity increased proportionally week to week, and this relationship was dynamic, strengthening between 2 and 3 weeks and diminishing by 4 weeks. Postsynaptic density 95 localization was dependent on culture duration. After 1 to 2 weeks, postsynaptic density 95 localized within somas but redistributed along neurites after 3 to 4 weeks. Axon initial segment scaffolding protein, Ankyrin G, expression also increased over time, and by 7 weeks, Ankyrin G often localized within putative axons. Voltage-gated inward currents progressively developed, but outward currents matured by 4 weeks. Current-induced spike generation increased over time but limited by depolarization block. Conclusions Human RGCs develop up to 7 weeks after culture. Thus, the state of hRGC maturation should be accounted for in designing models and treatments for optic neuropathies. Translational Relevance We characterized hRGC morphologic and physiologic development towards identifying key time points when hRGCs express mechanisms that may be harnessed to enhance the efficacy of neuroprotective and cell replacement therapies.
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Affiliation(s)
- Michael L Risner
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Silvia Pasini
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Xitiz Chamling
- Wilmer Eye Institute, Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Nolan R McGrady
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jeffrey L Goldberg
- Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Donald J Zack
- Wilmer Eye Institute, Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - David J Calkins
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
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Retinal Ganglion Cell Transplantation: Approaches for Overcoming Challenges to Functional Integration. Cells 2021; 10:cells10061426. [PMID: 34200991 PMCID: PMC8228580 DOI: 10.3390/cells10061426] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/01/2021] [Accepted: 06/03/2021] [Indexed: 02/07/2023] Open
Abstract
As part of the central nervous system, mammalian retinal ganglion cells (RGCs) lack significant regenerative capacity. Glaucoma causes progressive and irreversible vision loss by damaging RGCs and their axons, which compose the optic nerve. To functionally restore vision, lost RGCs must be replaced. Despite tremendous advancements in experimental models of optic neuropathy that have elucidated pathways to induce endogenous RGC neuroprotection and axon regeneration, obstacles to achieving functional visual recovery through exogenous RGC transplantation remain. Key challenges include poor graft survival, low donor neuron localization to the host retina, and inadequate dendritogenesis and synaptogenesis with afferent amacrine and bipolar cells. In this review, we summarize the current state of experimental RGC transplantation, and we propose a set of standard approaches to quantifying and reporting experimental outcomes in order to guide a collective effort to advance the field toward functional RGC replacement and optic nerve regeneration.
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Microfluidic and Microscale Assays to Examine Regenerative Strategies in the Neuro Retina. MICROMACHINES 2020; 11:mi11121089. [PMID: 33316971 PMCID: PMC7763644 DOI: 10.3390/mi11121089] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 12/03/2020] [Accepted: 12/05/2020] [Indexed: 12/15/2022]
Abstract
Bioengineering systems have transformed scientific knowledge of cellular behaviors in the nervous system (NS) and pioneered innovative, regenerative therapies to treat adult neural disorders. Microscale systems with characteristic lengths of single to hundreds of microns have examined the development and specialized behaviors of numerous neuromuscular and neurosensory components of the NS. The visual system is comprised of the eye sensory organ and its connecting pathways to the visual cortex. Significant vision loss arises from dysfunction in the retina, the photosensitive tissue at the eye posterior that achieves phototransduction of light to form images in the brain. Retinal regenerative medicine has embraced microfluidic technologies to manipulate stem-like cells for transplantation therapies, where de/differentiated cells are introduced within adult tissue to replace dysfunctional or damaged neurons. Microfluidic systems coupled with stem cell biology and biomaterials have produced exciting advances to restore vision. The current article reviews contemporary microfluidic technologies and microfluidics-enhanced bioassays, developed to interrogate cellular responses to adult retinal cues. The focus is on applications of microfluidics and microscale assays within mammalian sensory retina, or neuro retina, comprised of five types of retinal neurons (photoreceptors, horizontal, bipolar, amacrine, retinal ganglion) and one neuroglia (Müller), but excludes the non-sensory, retinal pigmented epithelium.
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Sheet S, Krishnamoorthy S, Park W, Lim D, Park JE, Ko M, Choi BH. Mechanistic insight into the progressive retinal atrophy disease in dogs via pathway-based genome-wide association analysis. JOURNAL OF ANIMAL SCIENCE AND TECHNOLOGY 2020; 62:765-776. [PMID: 33987558 PMCID: PMC7721568 DOI: 10.5187/jast.2020.62.6.765] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/25/2020] [Accepted: 09/06/2020] [Indexed: 01/01/2023]
Abstract
The retinal degenerative disease, progressive retinal atrophy (PRA) is a major
reason of vision impairment in canine population. Canine PRA signifies an
inherently dissimilar category of retinal dystrophies which has solid
resemblances to human retinis pigmentosa. Even though much is known about the
biology of PRA, the knowledge about the intricate connection among genetic loci,
genes and pathways associated to this disease in dogs are still remain unknown.
Therefore, we have performed a genome wide association study (GWAS) to identify
susceptibility single nucleotide polymorphisms (SNPs) of PRA. The GWAS was
performed using a case–control based association analysis method on PRA
dataset of 129 dogs and 135,553 markers. Further, the gene-set and pathway
analysis were conducted in this study. A total of 1,114 markers associations
with PRA trait at p < 0.01 were extracted and mapped to
640 unique genes, and then selected significant (p <
0.05) enriched 35 gene ontology (GO) terms and 5 Kyoto Encyclopedia of Genes and
Genomes (KEGG) pathways contain these genes. In particular, apoptosis process,
homophilic cell adhesion, calcium ion binding, and endoplasmic reticulum GO
terms as well as pathways related to focal adhesion, cyclic guanosine
monophosphate)-protein kinase G signaling, and axon guidance were more likely
associated to the PRA disease in dogs. These data could provide new insight for
further research on identification of potential genes and causative pathways for
PRA in dogs.
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Affiliation(s)
- Sunirmal Sheet
- Animal Genomics and Bioinformatics Division, National Institute of Animal Science, Rural Development Administration, Wanju 55365, Korea
| | - Srikanth Krishnamoorthy
- Animal Genomics and Bioinformatics Division, National Institute of Animal Science, Rural Development Administration, Wanju 55365, Korea
| | - Woncheoul Park
- Animal Genomics and Bioinformatics Division, National Institute of Animal Science, Rural Development Administration, Wanju 55365, Korea
| | - Dajeong Lim
- Animal Genomics and Bioinformatics Division, National Institute of Animal Science, Rural Development Administration, Wanju 55365, Korea
| | - Jong-Eun Park
- Animal Genomics and Bioinformatics Division, National Institute of Animal Science, Rural Development Administration, Wanju 55365, Korea
| | - Minjeong Ko
- Animal Genomics and Bioinformatics Division, National Institute of Animal Science, Rural Development Administration, Wanju 55365, Korea
| | - Bong-Hwan Choi
- Animal Genomics and Bioinformatics Division, National Institute of Animal Science, Rural Development Administration, Wanju 55365, Korea
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Wareham LK, Risner ML, Calkins DJ. Protect, Repair, and Regenerate: Towards Restoring Vision in Glaucoma. CURRENT OPHTHALMOLOGY REPORTS 2020; 8:301-310. [PMID: 33269115 PMCID: PMC7686214 DOI: 10.1007/s40135-020-00259-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/23/2020] [Indexed: 02/06/2023]
Abstract
PURPOSE OF REVIEW We summarize recent advances in strategies that aim to restore optic nerve function and vision in glaucoma through protective, reparative, and regenerative avenues. RECENT FINDINGS Neuroprotection relies on identification of early retinal ganglion cell dysfunction, which could prove challenging in the clinic. Cell replacement therapies show promise in restoring lost vision, but some hurdles remain in restoring visual circuitry in the retina and central connections in the brain. SUMMARY Identification and manipulation of intrinsic and extrinsic cellular mechanisms that promote axon regeneration in both resident and transplanted RGCs will drive future advances in vision restoration. Understanding the roles of multiple cell types in the retina that act in concert to promote RGC survival will aid efforts to promote neuronal health and restoration. Effective RGC transplantation, fine tuning axon guidance and growth, and synaptogenesis of transplanted and resident RGCs are still areas that require more research.
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Affiliation(s)
- Lauren K. Wareham
- Department of Ophthalmology and Visual Sciences and the Vanderbilt Eye Institute, Vanderbilt University Medical Center, AA7100 MCN, 1161 21st Ave S., Nashville, TN 37232 USA
| | - Michael L. Risner
- Department of Ophthalmology and Visual Sciences and the Vanderbilt Eye Institute, Vanderbilt University Medical Center, AA7100 MCN, 1161 21st Ave S., Nashville, TN 37232 USA
| | - David J. Calkins
- Department of Ophthalmology and Visual Sciences and the Vanderbilt Eye Institute, Vanderbilt University Medical Center, AA7100 MCN, 1161 21st Ave S., Nashville, TN 37232 USA
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Rabesandratana O, Chaffiol A, Mialot A, Slembrouck-Brec A, Joffrois C, Nanteau C, Rodrigues A, Gagliardi G, Reichman S, Sahel JA, Chédotal A, Duebel J, Goureau O, Orieux G. Generation of a Transplantable Population of Human iPSC-Derived Retinal Ganglion Cells. Front Cell Dev Biol 2020; 8:585675. [PMID: 33195235 PMCID: PMC7652757 DOI: 10.3389/fcell.2020.585675] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 09/24/2020] [Indexed: 12/18/2022] Open
Abstract
Optic neuropathies are a major cause of visual impairment due to retinal ganglion cell (RGC) degeneration. Human induced-pluripotent stem cells (iPSCs) represent a powerful tool for studying both human RGC development and RGC-related pathological mechanisms. Because RGC loss can be massive before the diagnosis of visual impairment, cell replacement is one of the most encouraging strategies. The present work describes the generation of functional RGCs from iPSCs based on innovative 3D/2D stepwise differentiation protocol. We demonstrate that targeting the cell surface marker THY1 is an effective strategy to select transplantable RGCs. By generating a fluorescent GFP reporter iPSC line to follow transplanted cells, we provide evidence that THY1-positive RGCs injected into the vitreous of mice with optic neuropathy can survive up to 1 month, intermingled with the host RGC layer. These data support the usefulness of iPSC-derived RGC exploration as a potential future therapeutic strategy for optic nerve regeneration.
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Affiliation(s)
| | - Antoine Chaffiol
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Antoine Mialot
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | | | - Corentin Joffrois
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Céline Nanteau
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Amélie Rodrigues
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | | | - Sacha Reichman
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - José-Alain Sahel
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France.,CHNO des Quinze-Vingts, INSERM-DHOS CIC 1423, Paris, France.,Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Alain Chédotal
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Jens Duebel
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Olivier Goureau
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Gael Orieux
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
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27
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Yao A, Wijngaarden P. Metabolic pathways in context:
mTOR
signalling in the retina and optic nerve ‐ A review. Clin Exp Ophthalmol 2020; 48:1072-1084. [DOI: 10.1111/ceo.13819] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/21/2020] [Accepted: 07/05/2020] [Indexed: 02/06/2023]
Affiliation(s)
- Anthony Yao
- Centre for Eye Research Australia Royal Victorian Eye and Ear Hospital East Melbourne, Victoria Australia
| | - Peter Wijngaarden
- Centre for Eye Research Australia Royal Victorian Eye and Ear Hospital East Melbourne, Victoria Australia
- Ophthalmology, Department of Surgery University of Melbourne Melbourne, Victoria Australia
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28
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Shen Y. Stem cell therapies for retinal diseases: from bench to bedside. J Mol Med (Berl) 2020; 98:1347-1368. [PMID: 32794020 DOI: 10.1007/s00109-020-01960-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 07/02/2020] [Accepted: 08/06/2020] [Indexed: 12/22/2022]
Abstract
As the human retina has no regenerative ability, stem cell interventions represent potential therapies for various blinding retinal diseases. This type of therapy has been extensively studied in the human eyes through decades of preclinical studies. The safety profiles shown in clinical trials thus far have indicated that these strategies should be further explored. There are still challenges with regard to cell source, cell delivery, immuno-related adverse events and long-term maintenance of the therapeutic effects. Retinal stem cell therapy is likely to be most successful with a combination of multiple technologies, such as gene therapy. The purpose of this review is to present a synthetical and systematic coverage of stem cell therapies that target retinal diseases from bench to bedside, intending to appeal to both junior specialists and the broader community of clinical investigators alike. This review will only focus on therapies that have already been studied in clinical trials. This review summarizes key concepts, highlights the main studies in human patients and discusses the current challenges and potential methods to reduce safety concerns while enhancing the therapeutic effects.
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Affiliation(s)
- Yuening Shen
- Institute of Ophthalmology, University College London , 11-43 Bath St, London, EC1V 9EL, UK. .,Department of Medical Retina, Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London, EC1V 2PD, UK.
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29
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Maiese K. Dysregulation of metabolic flexibility: The impact of mTOR on autophagy in neurodegenerative disease. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2020; 155:1-35. [PMID: 32854851 DOI: 10.1016/bs.irn.2020.01.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Non-communicable diseases (NCDs) that involve neurodegenerative disorders and metabolic disease impact over 400 million individuals globally. Interestingly, metabolic disorders, such as diabetes mellitus, are significant risk factors for the development of neurodegenerative diseases. Given that current therapies for these NCDs address symptomatic care, new avenues of discovery are required to offer treatments that affect disease progression. Innovative strategies that fill this void involve the mechanistic target of rapamycin (mTOR) and its associated pathways of mTOR complex 1 (mTORC1), mTOR complex 2 (mTORC2), AMP activated protein kinase (AMPK), trophic factors that include erythropoietin (EPO), and the programmed cell death pathways of autophagy and apoptosis. These pathways are intriguing in their potential to provide effective care for metabolic and neurodegenerative disorders. Yet, future work is necessary to fully comprehend the entire breadth of the mTOR pathways that can effectively and safely translate treatments to clinical medicine without the development of unexpected clinical disabilities.
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Affiliation(s)
- Kenneth Maiese
- Cellular and Molecular Signaling, New York, NY, United States.
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30
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Teotia P, Niu M, Ahmad I. Mapping developmental trajectories and subtype diversity of normal and glaucomatous human retinal ganglion cells by single-cell transcriptome analysis. Stem Cells 2020; 38:1279-1291. [PMID: 32557945 PMCID: PMC7586941 DOI: 10.1002/stem.3238] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 04/27/2020] [Accepted: 05/01/2020] [Indexed: 12/21/2022]
Abstract
Glaucoma is characterized by a progressive degeneration of retinal ganglion cells (RGCs), leading to irreversible vision loss. Currently, there is no effective treatment for RGC degeneration. We used a disease-in-a-dish stem cell model to examine the developmental susceptibility of RGCs to glaucomatous degeneration, which may inform on the formulation of therapeutic approaches. Here, we used single-cell transcriptome analysis of SIX6 risk allele (SIX6risk allele ) primary open angle glaucoma patient-specific and control hRGCs to compare developmental trajectories in terms of lineage- and stage-specific transcriptional signature to identify dysregulated stages/genes, and subtype composition to estimate the relative vulnerability of RGCs to degeneration because their ability to regenerate axons are subtype-specific. The developmental trajectories, beginning from neural stem cells to RGCs, were similar between SIX6risk allele and control RGCs. However, the differentiation of SIX6risk allele RGCs was relatively stalled at the retinal progenitor cell stage, compromising the acquisition of mature phenotype and subtype composition, compared with controls, which was likely due to dysregulated mTOR and Notch signaling pathways. Furthermore, SIX6risk allele RGCs, as compared with controls, expressed fewer genes corresponding to RGC subtypes that are preferentially resistant to degeneration. The immature phenotype of SIX6risk allele RGCs with underrepresented degeneration-resistant subtypes may make them vulnerable to glaucomatous degeneration.
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Affiliation(s)
- Pooja Teotia
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Meng Niu
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Iqbal Ahmad
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, USA
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31
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Lund-Ricard Y, Cormier P, Morales J, Boutet A. mTOR Signaling at the Crossroad between Metazoan Regeneration and Human Diseases. Int J Mol Sci 2020; 21:E2718. [PMID: 32295297 PMCID: PMC7216262 DOI: 10.3390/ijms21082718] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 04/09/2020] [Accepted: 04/10/2020] [Indexed: 02/06/2023] Open
Abstract
A major challenge in medical research resides in controlling the molecular processes of tissue regeneration, as organ and structure damage are central to several human diseases. A survey of the literature reveals that mTOR (mechanistic/mammalian target of rapamycin) is involved in a wide range of regeneration mechanisms in the animal kingdom. More particularly, cellular processes such as growth, proliferation, and differentiation are controlled by mTOR. In addition, autophagy, stem cell maintenance or the newly described intermediate quiescence state, Galert, imply upstream monitoring by the mTOR pathway. In this review, we report the role of mTOR signaling in reparative regenerations in different tissues and body parts (e.g., axon, skeletal muscle, liver, epithelia, appendages, kidney, and whole-body), and highlight how the mTOR kinase can be viewed as a therapeutic target to boost organ repair. Studies in this area have focused on modulating the mTOR pathway in various animal models to elucidate its contribution to regeneration. The diversity of metazoan species used to identify the implication of this pathway might then serve applied medicine (in better understanding what is required for efficient treatments in human diseases) but also evolutionary biology. Indeed, species-specific differences in mTOR modulation can contain the keys to appreciate why certain regeneration processes have been lost or conserved in the animal kingdom.
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Affiliation(s)
| | | | | | - Agnès Boutet
- Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, Integrative Biology of Marine Models (LBI2M), UMR 8227, Station Biologique de Roscoff (SBR), 29680 Roscoff, France; (Y.L.-R.); (P.C.); (J.M.)
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32
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Dronkers E, Wauters MMM, Goumans MJ, Smits AM. Epicardial TGFβ and BMP Signaling in Cardiac Regeneration: What Lesson Can We Learn from the Developing Heart? Biomolecules 2020; 10:biom10030404. [PMID: 32150964 PMCID: PMC7175296 DOI: 10.3390/biom10030404] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 02/29/2020] [Accepted: 03/02/2020] [Indexed: 12/31/2022] Open
Abstract
The epicardium, the outer layer of the heart, has been of interest in cardiac research due to its vital role in the developing and diseased heart. During development, epicardial cells are active and supply cells and paracrine cues to the myocardium. In the injured adult heart, the epicardium is re-activated and recapitulates embryonic behavior that is essential for a proper repair response. Two indispensable processes for epicardial contribution to heart tissue formation are epithelial to mesenchymal transition (EMT), and tissue invasion. One of the key groups of cytokines regulating both EMT and invasion is the transforming growth factor β (TGFβ) family, including TGFβ and Bone Morphogenetic Protein (BMP). Abundant research has been performed to understand the role of TGFβ family signaling in the developing epicardium. However, less is known about signaling in the adult epicardium. This review provides an overview of the current knowledge on the role of TGFβ in epicardial behavior both in the development and in the repair of the heart. We aim to describe the presence of involved ligands and receptors to establish if and when signaling can occur. Finally, we discuss potential targets to improve the epicardial contribution to cardiac repair as a starting point for future investigation.
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33
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Ahmad I, Teotia P, Erickson H, Xia X. Recapitulating developmental mechanisms for retinal regeneration. Prog Retin Eye Res 2019; 76:100824. [PMID: 31843569 DOI: 10.1016/j.preteyeres.2019.100824] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 12/06/2019] [Accepted: 12/11/2019] [Indexed: 12/18/2022]
Abstract
Degeneration of specific retinal neurons in diseases like glaucoma, age-related macular degeneration, and retinitis pigmentosa is the leading cause of irreversible blindness. Currently, there is no therapy to modify the disease-associated degenerative changes. With the advancement in our knowledge about the mechanisms that regulate the development of the vertebrate retina, the approach to treat blinding diseases through regenerative medicine appears a near possibility. Recapitulation of developmental mechanisms is critical for reproducibly generating cells in either 2D or 3D culture of pluripotent stem cells for retinal repair and disease modeling. It is the key for unlocking the neurogenic potential of Müller glia in the adult retina for therapeutic regeneration. Here, we examine the current status and potential of the regenerative medicine approach for the retina in the backdrop of developmental mechanisms.
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Affiliation(s)
- Iqbal Ahmad
- Department of Ophthalmology and Visual Science, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
| | - Pooja Teotia
- Department of Ophthalmology and Visual Science, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Helen Erickson
- Department of Ophthalmology and Visual Science, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Xiaohuan Xia
- Center for Translational Neurodegeneration and Regenerative Therapy, Shanghai Tenth People's Hospital Affiliated to Tongji University School of Medicine, Shanghai, 200072, China
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