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Eraslan M, Çerman E, Bozkurt S, Genç D, Virlan AT, Demir CS, Akkoç T, Karaöz E, Akkoç T. Mesenchymal stem cells differentiate to retinal ganglion-like cells in rat glaucoma model induced by polystyrene microspheres. Tissue Cell 2023; 84:102199. [PMID: 37633122 DOI: 10.1016/j.tice.2023.102199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 08/17/2023] [Accepted: 08/17/2023] [Indexed: 08/28/2023]
Abstract
AIM The study aimed to evaluate the differentiation ability of intravitreally injected rat bone marrow-derived mesenchymal stem cells (rBM-MSCs) to retinal ganglion-like cells in a polystyrene microsphere induced rat glaucoma model. MATERIALS AND METHODS The glaucoma rat model was generated via intracameral injection of 7 microliter polystyrene microspheres. Green fluorescence protein-labeled (GFP) rBM-MSCs were transplanted intravitreally at or after induction of ocular hypertension (OHT), depending on the groups. By the end of the fourth week, flat-mount retinal dissection was performed, and labeled against Brn3a, CD90, GFAP, CD11b, Vimentin, and localization of GFP positive rBM-MSCs was used for evaluation through immunofluorescence staining and to count differentiated retinal cells by flow cytometry. From 34 male Wistar albino rats, 56 eyes were investigated. RESULTS Flow cytometry revealed significantly increased CD90 and Brn3a positive cells in glaucoma induced and with rBM-MSC injected groups compared to control(P = 0.006 and P = 0.003 respectively), sham-operated (P = 0.007 and P < 0.001 respectively), and only rBM-MSCs injected groups (P = 0.002 and P = 0.009 respectively). Immunofluorescence microscopy revealed differentiation of GFP labeled stem cells to various retinal cells, including ganglion-like cells. rBM-MSCs were observable in ganglion cells, inner and outer nuclear retinal layers in rBM-MSCs injected eyes. CONCLUSION Intravitreally transplanted rBM-MSCs differentiated into retinal cells, including ganglion-like cells, which successfully created a glaucoma model damaged with polystyrene microspheres. Promisingly, MSCs may have a role in neuro-protection and neuro-regeneration treatment of glaucoma in the future.
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Affiliation(s)
- Muhsin Eraslan
- Department of Ophthalmology, Marmara University Faculty of Medicine, Istanbul, Turkey.
| | - Eren Çerman
- Department of Ophthalmology, Marmara University Faculty of Medicine, Istanbul, Turkey
| | - Süheyla Bozkurt
- Department of Pathology, Marmara University Faculty of Medicine, Istanbul, Turkey
| | - Deniz Genç
- Department of Pediatric Diseases, Faculty of Health Sciences, Muğla Sıtkı Koçman University, Muğla, Turkey
| | - Aysın Tulunay Virlan
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, Scotland, UK
| | - Cansu Subaşı Demir
- Center for Regenerative Medicine and Stem Cell Research & Manufacturing (LivMedCell), Istanbul, Turkey
| | - Tolga Akkoç
- Genetic Engineering and Biotechnology Institute, Tubitak Marmara Research Center, Kocaeli, Turkey
| | - Erdal Karaöz
- Department of Histology & Embryology, Istinye University Faculty of Medicine, Istanbul, Turkey; Center for Stem Cell and Tissue Engineering Research & Practice, Istinye University, Istanbul, Turkey
| | - Tunç Akkoç
- Department of Pediatric Allergy and Immunology, Marmara University Faculty of Medicine, Istanbul, Turkey; Department of Immunology, Marmara University Faculty of Medicine, Istanbul, Turkey; Marstem Cell Technologies, Marmara University Technopark, İstanbul, Turkey
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Reinehr S, Girbig RM, Schulte KK, Theile J, Asaad MA, Fuchshofer R, Dick H, Joachim SC. Enhanced glaucomatous damage accompanied by glial response in a new multifactorial mouse model. Front Immunol 2023; 13:1017076. [PMID: 36733392 PMCID: PMC9887307 DOI: 10.3389/fimmu.2022.1017076] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 12/19/2022] [Indexed: 01/18/2023] Open
Abstract
Introduction Glaucoma is a complex, multifactorial neurodegenerative disease, which can lead to blindness if left untreated. It seems that, among others, immune processes, elevated intraocular pressure (IOP), or a combination of these factors are responsible for glaucomatous damage. Here, we combined two glaucoma models to examine if a combination of risk factors (IOP and immune response) results in a more severe damage of retinal ganglion cells (RGCs) and the optic nerves as well as an additional glia activation. Methods Six-week-old wildtype (WT+ONA) and βB1-Connective Tissue Growth Factor (CTGF) mice (CTGF+ONA) were immunized with 1 mg ONA (optic nerve antigen). A WT and a CTGF control group (CTGF) received sodium chloride instead. IOP was measured before and every two weeks after immunization. After six weeks, electroretinogram (ERG) measurements were performed. Then, retinae and optic nerves were processed for (immuno-) histology. Further, mRNA levels of corresponding genes in optic nerve and retina were analyzed via RT-qPCR. Results Six weeks after immunization, the IOP in CTGF and CTGF+ONA mice was increased. The optic nerve of CTGF+ONA animals displayed the most severe cell inflammation, demyelination, and macroglia activation. Fewer numbers of oligodendrocytes were only observed in WT+ONA optic nerves, while more apoptotic cells triggered by the extrinsic pathway could be revealed in all three glaucoma groups. The number of microglia/macrophages was not altered within the optic nerves of all groups. The loss of neuronal cells, especially RGCs was most pronounced in CTGF+ONA retinae in the central part and this was accompanied by an enhanced activation of microglia/macrophages. Also, Müller cell activation could be noted in CTGF and CTGF+ONA retinae. Discussion In this new model, an additive degeneration could be noted in optic nerves as well as in the number of RGCs. These results suggest a potential additive role of high IOP and immune factors in glaucoma development, which will aid for understanding this multifactorial disease more precisely in the future.
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Affiliation(s)
- Sabrina Reinehr
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, Bochum, Germany,*Correspondence: Sabrina Reinehr,
| | - Renée M. Girbig
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Kim K. Schulte
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Janine Theile
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, Bochum, Germany
| | - M. Ali Asaad
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Rudolf Fuchshofer
- Institute of Human Anatomy and Embryology, University Regensburg, Regensburg, Germany
| | - H. Burkhard Dick
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Stephanie C. Joachim
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, Bochum, Germany
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Holden JM, Wareham LK. cGMP signaling: a potential therapeutic target for neurodegeneration in glaucoma? Neural Regen Res 2022; 18:1267-1268. [PMID: 36453407 PMCID: PMC9838148 DOI: 10.4103/1673-5374.360169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
- Joseph M. Holden
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Lauren K. Wareham
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, USA,Correspondence to: Lauren K. Wareham, .
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Haider AA, Rex TS, Wareham LK. cGMP Signaling in the Neurovascular Unit—Implications for Retinal Ganglion Cell Survival in Glaucoma. Biomolecules 2022; 12:biom12111671. [PMID: 36421684 PMCID: PMC9687235 DOI: 10.3390/biom12111671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 11/07/2022] [Accepted: 11/09/2022] [Indexed: 11/16/2022] Open
Abstract
Glaucoma is a progressive age-related disease of the visual system and the leading cause of irreversible blindness worldwide. Currently, intraocular pressure (IOP) is the only modifiable risk factor for the disease, but even as IOP is lowered, the pathology of the disease often progresses. Hence, effective clinical targets for the treatment of glaucoma remain elusive. Glaucoma shares comorbidities with a multitude of vascular diseases, and evidence in humans and animal models demonstrates an association between vascular dysfunction of the retina and glaucoma pathology. Integral to the survival of retinal ganglion cells (RGCs) is functional neurovascular coupling (NVC), providing RGCs with metabolic support in response to neuronal activity. NVC is mediated by cells of the neurovascular unit (NVU), which include vascular cells, glial cells, and neurons. Nitric oxide-cyclic guanosine monophosphate (NO-cGMP) signaling is a prime mediator of NVC between endothelial cells and neurons, but emerging evidence suggests that cGMP signaling is also important in the physiology of other cells of the NVU. NO-cGMP signaling has been implicated in glaucomatous neurodegeneration in humans and mice. In this review, we explore the role of cGMP signaling in the different cell types of the NVU and investigate the potential links between cGMP signaling, breakdown of neurovascular function, and glaucoma pathology.
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Holden JM, Al Hussein Al Awamlh S, Croteau LP, Boal AM, Rex TS, Risner ML, Calkins DJ, Wareham LK. Dysfunctional cGMP Signaling Leads to Age-Related Retinal Vascular Alterations and Astrocyte Remodeling in Mice. Int J Mol Sci 2022; 23:ijms23063066. [PMID: 35328488 PMCID: PMC8954518 DOI: 10.3390/ijms23063066] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Revised: 03/07/2022] [Accepted: 03/09/2022] [Indexed: 12/17/2022] Open
Abstract
The nitric oxide-guanylyl cyclase-1-cyclic guanylate monophosphate (NO-GC-1-cGMP) pathway is integral to the control of vascular tone and morphology. Mice lacking the alpha catalytic domain of guanylate cyclase (GC1-/-) develop retinal ganglion cell (RGC) degeneration with age, with only modest fluctuations in intraocular pressure (IOP). Increasing the bioavailability of cGMP in GC1-/- mice prevents neurodegeneration independently of IOP, suggesting alternative mechanisms of retinal neurodegeneration. In continuation to these studies, we explored the hypothesis that dysfunctional cGMP signaling leads to changes in the neurovascular unit that may contribute to RGC degeneration. We assessed retinal vasculature and astrocyte morphology in young and aged GC1-/- and wild type mice. GC1-/- mice exhibit increased peripheral retinal vessel dilation and shorter retinal vessel branching with increasing age compared to Wt mice. Astrocyte cell morphology is aberrant, and glial fibrillary acidic protein (GFAP) density is increased in young and aged GC1-/- mice, with areas of dense astrocyte matting around blood vessels. Our results suggest that proper cGMP signaling is essential to retinal vessel morphology with increasing age. Vascular changed are preceded by alterations in astrocyte morphology which may together contribute to retinal neurodegeneration and loss of visual acuity observed in GC1-/- mice.
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Gu C, Li A, Yu L. Diagnostic performance of laser speckle flowgraphy in glaucoma: a systematic review and meta-analysis. Int Ophthalmol 2021; 41:3877-3888. [PMID: 34327617 DOI: 10.1007/s10792-021-01954-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 07/09/2021] [Indexed: 11/26/2022]
Abstract
PURPOSE To evaluate the diagnostic value of laser speckle flowgraphy (LSFG) in glaucoma by investigating the mean blur rate (MBR) in the optic nerve head. METHODS Systematic literature search was performed in the CENTRAL, Web of Science, PubMed, and EMBASE databases to obtain relevant studies published until December 2020 without restrictions. The Newcastle-Ottawa Scale (NOS) was used for study quality assessment. The outcome measures included the MBRs of the entire (MA), vascular (MV), and tissue (MT) areas. Subgroup analyses were performed according to glaucoma type. All data were analyzed using RevMan and Comprehensive Meta-Analysis 3.3 software. RESULTS Fifteen studies, including 692 glaucomatous and 386 healthy eyes, were included. Of these, 11 studies reported the MA, MV, and MT, three studies only reported MT, and one study only reported MV. All were classified as case-control studies and had good NOS scores. The meta-analysis showed that the MA and MT were significantly reduced in glaucomatous eyes (mean difference [MD] - 5.59, 95% confidence interval [CI] - 6.19 to - 4.99, p = 0.1; MD - 2.2, 95% CI - 2.49 to - 1.91, p = 0.07, respectively) with moderate heterogeneity (p = 0.1, I2 = 38%; p = 0.07, I2 = 39%, respectively). There was also a significant difference in the MV between glaucomatous and healthy eyes (MD - 5.92, 95% CI - 7.77 to - 4.07) with significant heterogeneity (p = 0.0003, I2 = 69%). The subgroup analyses revealed significant differences in the MBR among different glaucoma types. CONCLUSIONS Glaucoma is closely related to ocular blood flow changes. This meta-analysis suggests that LSFG is a feasible diagnostic tool for glaucoma. However, further longitudinal prospective studies are needed.
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Affiliation(s)
- Chao Gu
- Department of Ophthalmology, Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China
| | - Ailing Li
- Department of the School of Public Health of Southwest Medical University, Luzhou, 646000, Sichuan, China
| | - Ling Yu
- Department of Ophthalmology, Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China.
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Wareham LK, Calkins DJ. The Neurovascular Unit in Glaucomatous Neurodegeneration. Front Cell Dev Biol 2020; 8:452. [PMID: 32656207 PMCID: PMC7325980 DOI: 10.3389/fcell.2020.00452] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 05/15/2020] [Indexed: 12/31/2022] Open
Abstract
Glaucoma is a neurodegenerative disease of the visual system and leading cause of blindness worldwide. The disease is associated with sensitivity to intraocular pressure (IOP), which over a large range of magnitudes stresses retinal ganglion cell (RGC) axons as they pass through the optic nerve head in forming the optic projection to the brain. Despite clinical efforts to lower IOP, which is the only modifiable risk factor for glaucoma, RGC degeneration and ensuing loss of vision often persist. A major contributor to failure of hypotensive regimens is the multifactorial nature of how IOP-dependent stress influences RGC physiology and structure. This stress is conveyed to the RGC axon through interactions with structural, glial, and vascular components in the nerve head and retina. These interactions promote pro-degenerative pathways involving biomechanical, metabolic, oxidative, inflammatory, immunological and vascular challenges to the microenvironment of the ganglion cell and its axon. Here, we focus on the contribution of vascular dysfunction and breakdown of neurovascular coupling in glaucoma. The vascular networks of the retina and optic nerve head have evolved complex mechanisms that help to maintain a continuous blood flow and supply of metabolites despite fluctuations in ocular perfusion pressure. In healthy tissue, autoregulation and neurovascular coupling enable blood flow to stay tightly controlled. In glaucoma patients evidence suggests these pathways are dysfunctional, thus highlighting a potential role for pathways involved in vascular dysfunction in progression and as targets for novel therapeutic intervention.
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Affiliation(s)
- Lauren K Wareham
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | - David J Calkins
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
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Fischer RA, Risner ML, Roux AL, Wareham LK, Sappington RM. Impairment of Membrane Repolarization Accompanies Axon Transport Deficits in Glaucoma. Front Neurosci 2019; 13:1139. [PMID: 31736686 PMCID: PMC6838637 DOI: 10.3389/fnins.2019.01139] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 10/09/2019] [Indexed: 12/12/2022] Open
Abstract
Glaucoma is a leading cause of blindness worldwide, resulting from degeneration of retinal ganglion cells (RGCs), which form the optic nerve. In glaucoma, axon transport deficits appear to precede structural degeneration of RGC axons. The period of time between the onset of axon transport deficits and the structural degeneration of RGC axons may represent a therapeutic window for the prevention of irreversible vision loss. However, it is unclear how deficits in axon transport relate to the electrophysiological capacity of RGCs to produce and maintain firing frequencies that encode visual stimuli. Here, we examined the electrophysiological signature of individual RGCs in glaucomatous retina with respect to axon transport facility. Utilizing the Microbead Occlusion Model of murine ocular hypertension, we performed electrophysiological recordings of RGCs with and without deficits in anterograde axon transport. We found that RGCs with deficits in axon transport have a reduced ability to maintain spiking frequency that arises from elongation of the repolarization phase of the action potential. This repolarization phenotype arises from reduced cation flux and K+ dyshomeostasis that accompanies pressure-induced decreases in Na/K-ATPase expression and activity. In vitro studies with purified RGCs indicate that elevated pressure induces early internalization of Na/K-ATPase that, when reversed, stabilizes cation flux and prevents K+ dyshomeostasis. Furthermore, pharmacological inhibition of the Na/K-ATPase is sufficient to replicate pressure-induced cation influx and repolarization phase phenotypes in healthy RGCs. These studies suggest that deficits in axon transport also likely reflect impaired electrophysiological function of RGCs. Our findings further identify a failure to maintain electrochemical gradients and cation dyshomeostasis as an early phenotype of glaucomatous pathology in RGCs that may have significant bearing on efforts to restore RGC health in diseased retina.
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Affiliation(s)
- Rachel A Fischer
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States
| | - Michael L Risner
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States.,Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, TN, United States
| | - Abigail L Roux
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Lauren K Wareham
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Rebecca M Sappington
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States.,Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States.,Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, TN, United States
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Garhöfer G, Schmetterer L. Nitric oxide: a drug target for glaucoma revisited. Drug Discov Today 2019; 24:1614-1620. [DOI: 10.1016/j.drudis.2019.05.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 03/11/2019] [Accepted: 05/31/2019] [Indexed: 02/06/2023]
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10
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Fischer RA, Roux AL, Wareham LK, Sappington RM. Pressure-dependent modulation of inward-rectifying K + channels: implications for cation homeostasis and K + dynamics in glaucoma. Am J Physiol Cell Physiol 2019; 317:C375-C389. [PMID: 31166711 DOI: 10.1152/ajpcell.00444.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Glaucoma is the leading cause of blindness worldwide, resulting from degeneration of retinal ganglion cells (RGCs), which form the optic nerve. Prior to structural degeneration, RGCs exhibit physiological deficits. Müller glia provide homeostatic regulation of ions that supports RGC physiology through a process called K+ siphoning. Recent studies suggest that several retinal conditions, including glaucoma, involve changes in the expression of K+ channels in Müller glia. To clarify whether glaucoma-related stressors directly alter expression and function of K+ channels in Müller glia, we examined changes in the expression of inwardly rectifying K+ (Kir) channels and two-pore domain (K2P) channels in response to elevated intraocular pressure (IOP) in vivo and in vitro in primary cultures of Müller glia exposed to elevated hydrostatic pressure. We then measured outcomes of cell health, cation homeostasis, and cation flux in Müller glia cultures. Transcriptome analysis in a murine model of microbead-induced glaucoma revealed pressure-dependent downregulation of Kir and K2P channels in vivo. Changes in the expression and localization of Kir and K2P channels in response to elevated pressure were also found in Müller glia in vitro. Finally, we found that elevated pressure compromises the plasma membrane of Müller glia and induces cation dyshomeostasis that involves changes in ion flux through cation channels. Pressure-induced changes in cation flux precede both cation dyshomeostasis and membrane compromise. Our findings have implications for Müller glia responses to pressure-related conditions, i.e., glaucoma, and identify cation dyshomeostasis as a potential contributor to electrophysiological impairment observed in RGCs of glaucomatous retina.
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Affiliation(s)
- Rachel A Fischer
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Abigail L Roux
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Lauren K Wareham
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Rebecca M Sappington
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee.,Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, Tennessee
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Matrix-bound nanovesicles prevent ischemia-induced retinal ganglion cell axon degeneration and death and preserve visual function. Sci Rep 2019; 9:3482. [PMID: 30837658 PMCID: PMC6400956 DOI: 10.1038/s41598-019-39861-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 01/25/2019] [Indexed: 01/07/2023] Open
Abstract
Injury to retinal ganglion cells (RGC), central nervous system neurons that relay visual information to the brain, often leads to RGC axon degeneration and permanently lost visual function. Herein this study shows matrix-bound nanovesicles (MBV), a distinct class of extracellular nanovesicle localized specifically to the extracellular matrix (ECM) of healthy tissues, can neuroprotect RGCs and preserve visual function after severe, intraocular pressure (IOP) induced ischemia in rat. Intravitreal MBV injections attenuated IOP-induced RGC axon degeneration and death, protected RGC axon connectivity to visual nuclei in the brain, and prevented loss in retinal function as shown by histology, anterograde axon tracing, manganese-enhanced magnetic resonance imaging, and electroretinography. In the optic nerve, MBV also prevented IOP-induced decreases in growth associated protein-43 and IOP-induced increases in glial fibrillary acidic protein. In vitro studies showed MBV suppressed pro-inflammatory signaling by activated microglia and astrocytes, stimulated RGC neurite growth, and neuroprotected RGCs from neurotoxic media conditioned by pro-inflammatory astrocytes. Thus, MBV can positively modulate distinct signaling pathways (e.g., inflammation, cell death, and axon growth) in diverse cell types. Since MBV are naturally derived, bioactive factors present in numerous FDA approved devices, MBV may be readily useful, not only experimentally, but also clinically as immunomodulatory, neuroprotective factors for treating trauma or disease in the retina as well as other CNS tissues.
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