| 1. |
- Barth, Henrik, et al.
(författare)
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A cross-linked hyaluronic acid hydrogel (Healaflow(®)) as a novel vitreous substitute
- 2016
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Ingår i: Graefe's Archives for Clinical and Experimental Ophthalmology. - : Springer. - 0721-832X .- 1435-702X. ; 254:4, s. 697-703
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Vitrectomy requires the substitution of the natural vitreous, as well as tamponading of retinal breaks. Clinically available alternatives such as gas and silicone oil have side effects such as inflammation, secondary glaucoma, cataract, and a need for head posturing. In this study, a hydrogel of cross-linked sodium hyaluronic acid (Healaflow(®)) is evaluated for use as a novel vitreous substitute.Methods: A combined 25-20-gauge pars plana vitrectomy with posterior vitreous detachment was performed in the right eye of twelve pigmented rabbits, with subsequent injection of approximately 1 ml Healaflow(®). Clinical evaluation, measurement of intraocular pressure (IOP), and full-field ERG were performed postoperatively. The rabbits were sacrificed at different time-points between 42 and 105 days. After enucleation, the eyes were examined macroscopically, photographed, and prepared for histological examination with routine microscopy and immunohistochemistry.Results: Healaflow(®) was successfully used with standard surgical procedures and remained translucent but did lose most of its viscosity during the postoperative period. One rabbit was lost due to unrelated causes. In two eyes iatrogenic partial retinal detachments were seen, and in two eyes significant cataract developed due to intra-operative complications. ERG-recordings revealed no toxic effect on rod or cone function. Routine microscopy and immunohistochemistry demonstrated normal morphology with some Müller cell activation (up-regulation of glial acidic fibrillary protein, GFAP) compared to unoperated eyes and no significant DNA-fragmentation (TUNEL-assay).Conclusions: Healaflow® did not affect retinal morphology or function negatively during long-term use as a vitreous substitute, making it highly interesting in this setting. An estimated retention time of a few weeks suggests potential for use as a short-term tamponade. Future work will include an increased ratio of cross-linking to prolong the structural integrity of the gel.
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| 2. |
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| 3. |
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| 4. |
- Barth, Henrik, et al.
(författare)
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Inflammatory responses after vitrectomy with vitreous substitutes in a rabbit model
- 2019
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Ingår i: Graefe's Archives for Clinical and Experimental Ophthalmology. - : Springer. - 0721-832X .- 1435-702X. ; 257:4, s. 769-783
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To investigate the inflammatory response of current and future potential vitreous substitutes in an experimental in vivo vitrectomy model.METHODS: Twenty-five gauge pars plana vitrectomy was performed in the right eye of 60 pigmented rabbits, with subsequent injection of 0.5-1.0 ml of Healaflow® (cross-linked hyaluronic acid, n = 12), Bio-Alcamid® (polyalkylimide, n = 8), silicone oil (n = 12), or balanced saline solution (BSS, n = 28). Postoperative clinical evaluation was performed; and the rabbits were sacrificed at 1 day, 1 week, or 1 month. The eyecups were then examined macroscopically; the retinas sectioned and stained with hematoxylin and eosin (Htx), and immunohistochemically labeled for glial fibrillary acidic protein (GFAP), CD45, galectin-3, CD68, and CD20. Unoperated left eyes from treated animals as well as eyes from untreated animals were used as controls.RESULTS: Vitrectomy without major complications was achieved in 46/60 eyes. The remaining 14 eyes were analyzed separately. One eye developed endophthalmitis after 1 week and was excluded. Eyes treated with Healaflow®, silicone oil, and BSS had a comparable appearance macroscopically and in Htx-stained sections, whereas Bio-Alcamid®-injected eyes exhibited increased macroscopic inflammation and severely affected retinas. GFAP upregulation was present in all treatment groups, most prominent in eyes treated with Bio-Alcamid® and silicone oil. Upregulation of CD45 and CD68 in the inner retina and vitreous space was most prominent with Bio-Alcamid® treatment, and these eyes together with their silicone oil-treated counterparts also displayed a stronger upregulation of CD20-labeled cells compared with remaining groups. General upregulation of galectin-3, mainly in the inner retina, was found in all groups. In eyes with perioperative complications, labeling of CD45, CD68, and especially GFAP was comparably high.CONCLUSIONS: We here describe differences in the postsurgery inflammatory profiles of existing and potential vitreous substitutes. Bio-Alcamid® and silicone oil display severe signs of gliosis and inflammation, whereas Healaflow® elicits minimal reactions comparable with BSS, highlighting its potential application as a vitreous substitute in a future clinical setting.
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| 5. |
- Berntsson, Fredrik, et al.
(författare)
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A one dimensional model of blood flow through a curvilinear artery
- 2018
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Ingår i: Applied Mathematical Modelling. - : ELSEVIER SCIENCE INC. - 0307-904X .- 1872-8480. ; 63, s. 633-643
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Tidskriftsartikel (refereegranskat)abstract
- We present a one-dimensional model describing the blood flow through a moderately curved and elastic blood vessel. We use an existing two dimensional model of the vessel wall along with Navier-Stokes equations to model the flow through the channel while taking factors, namely, surrounding muscle tissue and presence of external forces other than gravity into account. Our model is obtained via a dimension reduction procedure based on the assumption of thinness of the vessel relative to its length. Results of numerical simulations are presented to highlight the influence of different factors on the blood flow. (C) 2018 Elsevier Inc. All rights reserved.
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| 6. |
- Bro, T, et al.
(författare)
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Floorball-related eye injuries: The impact of protective eyewear.
- 2016
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Ingår i: Scandinavian Journal of Medicine & Science in Sports. - : Wiley. - 1600-0838 .- 0905-7188.
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Tidskriftsartikel (refereegranskat)abstract
- Several previous studies have shown that floorball belongs to a high-risk group of sports in terms of eye injuries. Protective eyewear is available, but the extent of its use and impact on eye injuries are unknown. The purpose of this study was to investigate the current incidence of eye injuries caused by floorball and to compare it with the present use of protective eyewear. Medical records were used to identify all eye injuries suffered while playing floorball in Jönköping County from 2008 to 2011 (N = 167). All these patients were sent a questionnaire that included inquiries about the use of protective eyewear. The study shows that floorball caused more eye injuries than all other sports combined (56%). Prolonged decreased visual acuity was very unusual (0.5%), but moderate eye injuries with some risk of future problems were seen in 62% of the sample. More than one fifth of the injured patients reported some kind of vision-related problem 2-7 years after the original injury. Only one player had been using protective eyewear at the time of injury. Our results underline the importance of protective eyewear to prevent floorball-related injuries.
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| 7. |
- Ghosh, Fredrik, et al.
(författare)
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Acute tissue reactions, inner segment pathology, and effects of the antioxidant α1-microglobulin in an in vitro model of retinal detachment
- 2018
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Ingår i: Experimental Eye Research. - : Elsevier BV. - 0014-4835. ; 173, s. 13-23
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to explore acute tissue reactions, ultrastructural photoreceptor morphology with emphasis on inner segments, and the effect of antioxidant treatment in an in vitro model of rhegmatogenous retinal detachment (RRD). A previously described method of RRD simulation was used with adult retinal porcine explants kept free-floating in culture medium with or without treatment with the radical scavenger α1-microglobulin (A1M). Explants were examined at 5 time points from 1 to 24 h using transmission electron microscopy as well as quantitative real-time PCR (RT-PCR) to quantify gene expression of the cell stress marker heat shock protein 70 (Hsp70) and oxidative stress marker heme oxygenase (HO-1). The culture medium level of the cell damage marker lactate dehydrogenase (LDH) and oxidative stress DNA damage marker 8-Oxo-2'-deoxyguanosine (8-OHdG) was also assessed at each time point. We found that the levels of Hsp70 and LDH rapidly increased in both groups, and at 3 and 6 h, Hsp70 was significantly higher in A1M treated retinas. At 24 h, Hsp70 and LDH, as well as 8-OHdG were significantly lower compared with controls, whereas the tissue level of HO-1 was significantly higher. Progressive ultrastructural photoreceptor changes were seen in untreated control explants from 1 h and onwards including outer segment shortening and loss, disruption of organelles within the inner segments and loss of perikarya in the outer nuclear layer. Inner segment pathology was more rapid and extensive in rods compared with in cones. In A1M treated counterparts, damage to rod inner segment mitochondria was significantly higher after 1 h of culture, but after this time, no statistical difference was found. At 24 h, cone inner segment mitochondrial disruption was significantly higher in control retinas and the number of surviving perikarya lower. From our results, we conclude that retinal explants elicit acute cell stress reactions when placed in culture without physical support simulating a detached retina floating in the vitreous space. Photoreceptors rapidly display degenerative changes including extensive damage to inner segment mitochondria indicating loss of energy transduction as an early key event. A1M increases initial mitochondrial stress in the rods, however, subsequent pathology is attenuated by the treatment, highlighting the dynamics of protective as well as disruptive oxidative stress reactions in the detached retina.
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| 8. |
- Ghosh, Fredrik, et al.
(författare)
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In vitro biomechanical modulation-retinal detachment in a box.
- 2016
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Ingår i: Graefe's Archive for Clinical and Experimental Ophthalmology. - : Springer Science and Business Media LLC. - 1435-702X .- 0721-832X. ; 254:3, s. 475-487
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Tidskriftsartikel (refereegranskat)abstract
- To illustrate the importance of biomechanical impact on tissue health within the central nervous system (CNS), we herein describe an in vitro model of rhegmatogenous retinal detachment (RRD) in which disruption and restoration of physical tissue support can be studied in isolation.
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| 9. |
- Ghosh, Fredrik, et al.
(författare)
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Retinal neuroinflammatory induced neuronal degeneration - Role of toll-like receptor-4 and relationship with gliosis
- 2018
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Ingår i: Experimental Eye Research. - : Elsevier BV. - 0014-4835. ; 169, s. 99-110
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to explore retina-intrinsic neuroinflammatory reactions, effects on neuronal survival, relationship with classic gliosis, and possible role of the toll-like receptor 4 (TLR4). To isolate the adult retina from the systemic immune system, a previously described large animal explant culture model was used in which full-thickness porcine retinal sheets can be kept in vitro for extended time periods. Explants were kept for 5 days in vitro (DIV) and were treated with either; lipopolysaccharide (LPS), a Toll-like receptor-4 (TLR4) inhibitor (CLI-095), LPS + CLI-095, or solvent vehicle throughout the culture period after which retinal sections were examined with hematoxylin and eosin staining and extensive immunohistochemistry. In addition, the culture medium of all explants was assayed for a panel of cytokines at 2 and 5DIV. Compared with in vivo controls, vehicle controls (CT) as well as CLI-095 explants displayed moderate reduction of total thickness and number of retinal neurons with upregulation of glial fibrillary acidic protein (GFAP) throughout the Müller cells. In contrast, LPS and LPS + CLI-095 treated counterparts showed extensive overall thinning with widespread neuronal degeneration but only minimal signs of classical Müller cell gliosis (limited upregulation of GFAP and no downregulation of glutamine synthetase (GS). These specimens also displayed a significantly increased expression of galectin-3 and TGF-beta activated kinase 1 (TAK1). Multiplex proteomic analysis of culture medium at 2DIV revealed elevated levels of IL-1β, IL-6, IL-4 and IL-12 in LPS-treated explants compared to CLI-095 and CT counterparts. LPS stimulation of the isolated adult retina results in substantial neuronal cell death despite only minimal signs of gliosis indicating a retina-intrinsic neuroinflammatory response directly related to the degenerative process. This response is characterized by early upregulation of several inflammatory related cytokines with subsequent upregulation of Galectin-3, TLR4 and TAK1. Pharmacological block of TLR4 does not attenuate neuronal loss indicating that LPS induced retinal degeneration is mediated by TLR4 independent neuroinflammatory pathways.
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| 10. |
- Taylor, Linnéa, et al.
(författare)
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Complimentary action : C1q increases ganglion cell survival in an in vitro model of retinal degeneration
- 2016
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Ingår i: Journal of Neuroimmunology. - : Elsevier BV. - 0165-5728. ; 298, s. 117-129
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Tidskriftsartikel (refereegranskat)abstract
- Using a previously described retinal explant culture system as an acute injury model, we here explore the role of C1q, the initiator of the classical complement pathway, in neuronal cell survival and retinal homeostasis. Full-thickness adult rat retinal explants were divided into four groups, receiving the following supplementation: C1q (50 nM), C1-inhibitor (C1-inh; Berinert; 500 mg/l), C1q + C1-inh, and no supplementation (culture controls). Explants were kept for 12 h or 2 days after which they were examined morphologically and with a panel of immunohistochemical markers. C1q supplementation protects ganglion cells from degeneration within the explant in vitro system. This effect is correlated to an attenuated endogenous production of C1q, and a quiesced gliotic response.
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| 11. |
- Taylor, Linnéa, et al.
(författare)
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First Responders: Dynamics of Pre-Gliotic Müller Cell Responses in The Isolated Adult Rat Retina.
- 2015
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Ingår i: Current Eye Research. - : Informa UK Limited. - 0271-3683 .- 1460-2202. ; 40:12, s. 1245-1260
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Purpose: To explore the early reactions of the retinal Müller glia in response to retinal insult prior to gliotic remodeling and the sustained upregulation of intermediate filament glial fibrillary acidic protein (GFAP), which has traditionally been considered the most sensitive early indicator of reactive gliosis. Methods: To study pre-gliotic events, we used a model of adult rat retinal explants and related the dynamic expression of GFAP as well as apoptosis, to four key regulators of retinal homeostasis (glutamine synthetase (GS), cellular retinaldehyde binding protein (CRALBP), basic fibroblast growth factor (bFGF), carbonic anhydrase II (CAII)) using immunohistochemistry. Results: We found that a sustained GFAP upregulation couple with gliotic remodeling occurred comparatively late and that this phenomenon was preceded by an initial upregulation followed by depletion of GS, CRALBP, bFGF and CAII in retinal Müller cells. The initial increase of the regulatory proteins, seen after 1-12 h, preceded a first phase of moderate apoptosis, and their depletion after 48 h was followed by massive apoptosis and widespread GFAP upregulation in the Müller cells at 5 days. Conclusion: We conclude that, in the explant model, changes in the expression of the four homeostatic regulatory proteins as well as apoptotic cell death precedes sustained GFAP upregulation and reactive gliosis. Müller cell reactivity has been linked to several retinal conditions, and the herein provided novel information on the dynamics of pre-gliotic events in the lesioned retina may help us understand important pathological mechanisms crucial for future therapeutic intervention.
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| 12. |
- Taylor, Linnéa, et al.
(författare)
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N-methyl-N-nitrosourea-induced neuronal cell death in a large animal model of retinal degeneration in vitro
- 2016
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Ingår i: Experimental Eye Research. - : Elsevier BV. - 0014-4835. ; 148, s. 55-64
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Tidskriftsartikel (refereegranskat)abstract
- N-methyl-N-nitrosourea (MNU) has been reported to induce photoreceptor-specific degeneration with minimal inner retinal impact in small animals in vivo. Pending its use within a retinal transplantation paradigm, we here explore the effects of MNU on outer and inner retinal neurons and glia in an in vitro large animal model of retinal degeneration. The previously described degenerative culture explant model of adult porcine retina was used and compared with explants receiving 10 or 100 μg/ml MNU (MNU10 and MNU100) supplementation. All explants were kept for 5 days in vitro, and examined for morphology as well as for glial and neuronal immunohistochemical markers. Rhodopsin-labeled photoreceptors were present in all explants. The number of cone photoreceptors (transducin), rod bipolar cells (PKC) and horizontal cells (calbindin) was significantly lower in MNU treated explants (p <0.001). Gliosis was attenuated in MNU10 treated explants, with expression of vimentin, glial fibrillary protein (GFAP), glutamine synthetase (GS), and bFGF comparable to in vivo controls. In corresponding MNU100 counterparts, the expression of Müller cell proteins was almost extinguished. We here show that MNU causes degeneration of outer and inner retinal neurons and glia in the adult porcine retina in vitro. MNU10 explants display attenuation of gliosis, despite decreased neuronal survival compared with untreated controls. Our results have impact on the use of MNU as a large animal photoreceptor degeneration model, on tissue engineering related to retinal transplantation, and on our understanding of gliosis related neuronal degenerative cell death.
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| 13. |
- Taylor, Linnéa, et al.
(författare)
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Scaffolding the retina: The interstitial extracellular matrix during rat retinal development.
- 2015
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Ingår i: International Journal of Developmental Neuroscience. - : Wiley. - 1873-474X .- 0736-5748. ; 42, s. 46-58
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To examine the expression of interstitial extracellular matrix components and their role during retinal development. MATERIAL AND METHODS: Fibronectin (FN), collagen IV (Coll IV) and laminin 5 (Lam 5) expression in rat retinas from developmental stages E17 to adult were studied. In addition, PN5 full-thickness retinas were cultured for 7 days with dispase, which selectively cleaves FN and Coll IV, at either 0.5U/ml or 5.0U/ml for 3 or 24h. Eyecups and retinal cultures were examined morphologically using hematoxylin and eosin staining and immunohistochemistry. RESULTS: Coll IV, Lam 5 and FN were all transiently expressed in the interstitial matrix of the retinal layers during development. The retinal layers in dispase treated explants was severely disturbed in a dose and time dependent manner. CONCLUSIONS: FN, Lam 5 and Coll IV, are present in the interstitial extracellular matrix during rat retinal development. Enzymatic cleavage of FN and Coll IV early in the lamination process disrupts the retinal layers implicating their pivotal role in this process.
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| 14. |
- Taylor, Linnéa, et al.
(författare)
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Seeing through the interface : Poly(ε-Caprolactone) surface modification of poly(glycerol-co-sebacic acid) membranes in adult porcine retinal explants
- 2017
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Ingår i: Journal of Tissue Engineering and Regenerative Medicine. - : Hindawi Limited. - 1932-6254. ; 11:8, s. 2349-2358
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to investigate the adhesion properties and tissue reactions in an in vitro model of nanofabricated membranes emulating the vitreous cortex. Electrospinning was performed for either 5, 10 or 15 min to create various thicknesses of poly(ε-caprolactone) (PCL) fibre mats on a poly(glycerol-co-sebacic acid) (PGS) surface. These were fused with adult porcine retinal explants, with the fibre side facing the inner retina, and cultured for 5 days. Adherence was assessed by macroscopic inspection, and morphological and immunohistochemical analysis was performed using haematoxylin and eosin (H&E) and markers for photoreceptors and Müller glia (recoverin, NeuN, vimentin and GFAP). TUNEL labelling was performed to assess apoptosis. Five minute specimens displayed poor adherence with an overall structure, apoptosis and photoreceptor and ganglion cell morphology comparable to that of the culture controls, whereas 10 min specimens showed improved neuronal survival; 15 min composite explants adhered only at focal points, were thin and showed extensive degenerative damage. The physical composition of nanofibre meshes is important for adhesion to the inner retina and has a significant impact on neuronal and glial survival in vitro. The results bearing on research involving retinal transplantation are discussed.
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| 15. |
- Taylor, Linnéa, et al.
(författare)
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Specific inhibition of TRPV4 enhances retinal ganglion cell survival in adult porcine retinal explants
- 2017
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Ingår i: Experimental Eye Research. - : Elsevier BV. - 0014-4835. ; 154, s. 10-21
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Tidskriftsartikel (refereegranskat)abstract
- Signaling through the polymodal cation channel Transient Receptor Potential Vanilloid 4 (TRPV4) has been implicated in retinal neuronal degeneration. To further outline the involvement of this channel in this process, we here explore modulation of Transient Receptor Potential Vanilloid 4 (TRPV4) activity on neuronal health and glial activation in an in vitro model of retinal degeneration. For this purpose, adult porcine retinal explants were cultured using a previously established standard protocol for up to 5 days with specific TRPV4 agonist GSK1016790A (GSK), or specific antagonist RN-1734, or culture medium only. Glial and neuronal cell health were evaluated by a battery of immunohistochemical markers, as well as morphological staining. Specific inhibition of TRPV4 by RN-1734 significantly enhanced ganglion cell survival, improved the maintenance of the retinal laminar architecture, reduced apoptotic cell death and attenuated the gliotic response as well as preserved the expression of TRPV4 in the plexiform layers and ganglion cells. In contrast, culture controls, as well as specimens treated with GSK, displayed rapid remodeling and neurodegeneration as well as a downregulation of TRPV4 and the Müller cell homeostatic mediator glutamine synthetase. Our results indicate that TRPV4 signaling is an important contributor to the retinal degeneration in this model, affecting neuronal cell health and glial homeostasis. The finding that pharmacological inhibition of the receptor significantly attenuates neuronal degeneration and gliosis in vitro, suggests that TRPV4 signaling may be an interesting pharmaceutical target to explore for treatment of retinal degenerative disease.
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| 16. |
- Åkerström, Bo, et al.
(författare)
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The Role of Mitochondria, Oxidative Stress, and the Radical-binding Protein A1M in Cultured Porcine Retina.
- 2017
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Ingår i: Current Eye Research. - : Informa UK Limited. - 0271-3683 .- 1460-2202. ; 42:6, s. 948-961
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The purpose of this study was to explore the relationship between oxidative stress, antioxidant defense, mitochondrial structure, and biomechanical tissue support in the isolated porcine retina.Methods: Full-thickness retinal sheets were isolated from adult porcine eyes. Retinas were cultured for 2 or 48 h using (1) a previously established low-support explant protocol with photoreceptors positioned against the culture membrane (porous polycarbonate) or (2) a high-support procedure developed by our group, apposing the Müller cell endfeet and inner limiting membrane against the membrane. The grafts were analyzed by quantitative polymerase chain reaction (PCR), immunohistochemistry, and transmission electron microscopy (TEM), and culture medium was assayed for the cell damage and oxidative stress markers lactate dehydrogenase and protein carbonyls.Results: In explants cultured with physical support to the inner border, cone photoreceptors were preserved and lactate dehydrogenase levels were reduced, although an initial (2 h), transient, increased oxidative stress was observed. Elevated expression of the antioxidants α1-microglobulin and heme oxygenase-1 was seen in the mitochondria-rich inner segments after 48 h compared to low-support counterparts. Housekeeping gene expression suggested a higher degree of structural integrity of mitochondria in high-support explants, and TEM of inner segments confirmed preservation of a normal mitochondrial morphology.Conclusion: Providing retinal explants with inner retinal support leads to mobilization of antioxidant proteins, preservation of mitochondrial function, and increased cell viability. Consequently, the failure of low-support retinal cultures to mobilize an adequate response to the oxidative environment may play a key role in their rapid demise. These findings shed new light on pathological reactions in biomechanically related conditions in vivo.
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