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Mu Y, Zhang N, Wei D, Yang G, Yao L, Xu X, Li Y, Xue J, Zhang Z, Chen T. Müller cells are activated in response to retinal outer nuclear layer degeneration in rats subjected to simulated weightlessness conditions. Neural Regen Res 2025; 20:2116-2128. [PMID: 39254570 DOI: 10.4103/nrr.nrr-d-23-01035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 01/07/2024] [Indexed: 09/11/2024] Open
Abstract
JOURNAL/nrgr/04.03/01300535-202507000-00032/figure1/v/2024-09-09T124005Z/r/image-tiff A microgravity environment has been shown to cause ocular damage and affect visual acuity, but the underlying mechanisms remain unclear. Therefore, we established an animal model of weightlessness via tail suspension to examine the pathological changes and molecular mechanisms of retinal damage under microgravity. After 4 weeks of tail suspension, there were no notable alterations in retinal function and morphology, while after 8 weeks of tail suspension, significant reductions in retinal function were observed, and the outer nuclear layer was thinner, with abundant apoptotic cells. To investigate the mechanism underlying the degenerative changes that occurred in the outer nuclear layer of the retina, proteomics was used to analyze differentially expressed proteins in rat retinas after 8 weeks of tail suspension. The results showed that the expression levels of fibroblast growth factor 2 (also known as basic fibroblast growth factor) and glial fibrillary acidic protein, which are closely related to Müller cell activation, were significantly upregulated. In addition, Müller cell regeneration and Müller cell gliosis were observed after 4 and 8 weeks, respectively, of simulated weightlessness. These findings indicate that Müller cells play an important regulatory role in retinal outer nuclear layer degeneration during weightlessness.
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Affiliation(s)
- Yuxue Mu
- Aerospace Clinical Medical Center, School of Aerospace Medicine, Air Force Medical University, Xi'an, Shaanxi Province, China
- Department of Aviation Medicine, Xijing Hospital, Air Force Medical University, Xi'an, Shaanxi Province, China
| | - Ning Zhang
- Department of Emergency Medicine, Wuhan No.1 Hospital, Wuhan, Hubei Province, China
| | - Dongyu Wei
- Aerospace Clinical Medical Center, School of Aerospace Medicine, Air Force Medical University, Xi'an, Shaanxi Province, China
| | - Guoqing Yang
- Aerospace Clinical Medical Center, School of Aerospace Medicine, Air Force Medical University, Xi'an, Shaanxi Province, China
| | - Lilingxuan Yao
- Third Regiment, School of Basic Medicine, Air Force Medical University, Xi'an, Shaanxi Province, China
| | - Xinyue Xu
- Aerospace Clinical Medical Center, School of Aerospace Medicine, Air Force Medical University, Xi'an, Shaanxi Province, China
| | - Yang Li
- Fourth Regiment, School of Basic Medicine, Air Force Medical University, Xi'an, Shaanxi Province, China
| | - Junhui Xue
- Aerospace Clinical Medical Center, School of Aerospace Medicine, Air Force Medical University, Xi'an, Shaanxi Province, China
- Department of Aviation Medicine, Xijing Hospital, Air Force Medical University, Xi'an, Shaanxi Province, China
| | - Zuoming Zhang
- Aerospace Clinical Medical Center, School of Aerospace Medicine, Air Force Medical University, Xi'an, Shaanxi Province, China
| | - Tao Chen
- Aerospace Clinical Medical Center, School of Aerospace Medicine, Air Force Medical University, Xi'an, Shaanxi Province, China
- Department of Aviation Medicine, Xijing Hospital, Air Force Medical University, Xi'an, Shaanxi Province, China
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Caddy HT, Fujino M, Vahabli E, Voigt V, Kelsey LJ, Dilley RJ, Carvalho LS, Takahashi S, Green DJ, Doyle BJ. Simulation of murine retinal hemodynamics in response to tail suspension. Comput Biol Med 2024; 182:109148. [PMID: 39298883 DOI: 10.1016/j.compbiomed.2024.109148] [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: 04/12/2024] [Revised: 09/03/2024] [Accepted: 09/08/2024] [Indexed: 09/22/2024]
Abstract
The etiology of spaceflight-associated neuro-ocular syndrome (SANS) remains unclear. Recent murine studies indicate there may be a link between the space environment and retinal endothelial dysfunction. Post-fixed control (N = 4) and 14-day tail-suspended (TS) (N = 4) mice eye samples were stained and imaged for the vessel plexus and co-located regions of endothelial cell death. A custom workflow combined whole-mounted and tear reconstructed three-dimensional (3D) spherical retinal plexus models with computational fluid dynamics (CFD) simulation that accounted for the Fåhræus-Lindqvist effect and boundary conditions that accommodated TS fluid pressure measurements and deeper capillary layer blood flow distribution. TS samples exhibited reduced surface area (4.6 ± 0.5 mm2 vs. 3.5 ± 0.3 mm2, P = 0.010) and shorter lengths between branches in small vessels (<10 μm, 69.5 ± 0.6 μm vs. 60.4 ± 1.1 μm, P < 0.001). Wall shear stress (WSS) and pressure were higher in TS mice compared to controls, particularly in smaller vessels (<10 μm, WSS: 6.57 ± 1.08 Pa vs. 4.72 ± 0.67 Pa, P = 0.034, Pressure: 72.04 ± 3.14 mmHg vs. 50.64 ± 6.74 mmHg, P = 0.004). Rates of retinal endothelial cell death were variable in TS mice compared to controls. WSS and pressure were generally higher in cell death regions, both within and between cohorts, but significance was variable and limited to small to medium-sized vessels (<20 μm). These findings suggest a link may exist between emulated microgravity and retinal endothelial dysfunction that may have implications for SANS development. Future work with increased sample sizes of larger species or spaceflight cohorts should be considered.
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Affiliation(s)
- Harrison T Caddy
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre, Nedlands, Australia and the UWA Centre for Medical Research, The University of Western Australia, Perth, Australia; School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, Perth, Australia
| | - Mitsunori Fujino
- Department of Anatomy and Embryology, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan; Ph.D. Program in Human Biology, School of Integrative and Global Majors, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Ebrahim Vahabli
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre, Nedlands, Australia and the UWA Centre for Medical Research, The University of Western Australia, Perth, Australia; School of Engineering, The University of Western Australia, Perth, Australia; T3mPLATE, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre and UWA Centre for Medical Research, The University of Western Australia, Perth, Australia
| | - Valentina Voigt
- Centre for Experimental Immunology, Lions Eye Institute, Nedlands, Australia
| | - Lachlan J Kelsey
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre, Nedlands, Australia and the UWA Centre for Medical Research, The University of Western Australia, Perth, Australia; School of Engineering, The University of Western Australia, Perth, Australia
| | - Rodney J Dilley
- T3mPLATE, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre and UWA Centre for Medical Research, The University of Western Australia, Perth, Australia
| | - Livia S Carvalho
- Retinal Genomics and Therapy Group, Centre for Ophthalmology and Visual Sciences (incorporating Lions Eye Institute), The University of Western Australia, Perth, Australia; Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Satoru Takahashi
- Department of Anatomy and Embryology, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan; Laboratory Animal Resource Center, University of Tsukuba, Tsukuba, Ibaraki, Japan; Life Science Center, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Tsukuba, Ibaraki, Japan; International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki, Japan; Transborder Medical Research Center, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Daniel J Green
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, Perth, Australia
| | - Barry J Doyle
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre, Nedlands, Australia and the UWA Centre for Medical Research, The University of Western Australia, Perth, Australia; School of Engineering, The University of Western Australia, Perth, Australia.
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Grigoryan EN. Impact of Microgravity and Other Spaceflight Factors on Retina of Vertebrates and Humans In Vivo and In Vitro. Life (Basel) 2023; 13:1263. [PMID: 37374046 PMCID: PMC10305389 DOI: 10.3390/life13061263] [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: 04/04/2023] [Revised: 05/20/2023] [Accepted: 05/25/2023] [Indexed: 06/29/2023] Open
Abstract
Spaceflight (SF) increases the risk of developmental, regenerative, and physiological disorders in animals and humans. Astronauts, besides bone loss, muscle atrophy, and cardiovascular and immune system alterations, undergo ocular disorders affecting posterior eye tissues, including the retina. Few studies revealed abnormalities in the development and changes in the regeneration of eye tissues in lower vertebrates after SF and simulated microgravity. Under microgravity conditions, mammals show disturbances in the retinal vascular system and increased risk of oxidative stress that can lead to cell death in the retina. Animal studies provided evidence of gene expression changes associated with cellular stress, inflammation, and aberrant signaling pathways. Experiments using retinal cells in microgravity-modeling systems in vitro additionally indicated micro-g-induced changes at the molecular level. Here, we provide an overview of the literature and the authors' own data to assess the predictive value of structural and functional alterations for developing countermeasures and mitigating the SF effects on the human retina. Further emphasis is given to the importance of animal studies on the retina and other eye tissues in vivo and retinal cells in vitro aboard spacecraft for understanding alterations in the vertebrate visual system in response to stress caused by gravity variations.
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Affiliation(s)
- Eleonora N Grigoryan
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 119334 Moscow, Russia
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Li S, Song Q, Wu B, Kan G, Wang F, Yang J, Zhu S. Structural damage to the rat eye following long-term simulated weightlessness. Exp Eye Res 2022; 223:109200. [PMID: 35932903 DOI: 10.1016/j.exer.2022.109200] [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: 01/01/2022] [Revised: 06/14/2022] [Accepted: 07/18/2022] [Indexed: 11/29/2022]
Abstract
To better perform space missions and develop human spaceflights, the eye health of astronauts is receiving increasing attention from researchers. In this study, we used prolonged tail suspension to simulate microgravity cephalad fluid shift in space to observe intraocular pressure (IOP) changes, retinal structure, and optic nerve damage in rats. We observed significant choroidal thickening and optic nerve demyelination lesions in the rats in each experimental group. At the cellular level, retinal ganglion cells (RGCs) survival was significantly reduced, optic nerve oligodendrocytes were reduced, and apoptotic factors and microglia-mediated inflammation-related factors were detected in both the retina and optic nerve. The severity of these changes increased with increasing tails suspension time. In conclusion, simulated long-term microgravity can lead to slight intraocular pressure fluctuations, choroidal thickening, reduced RGCs survival, and optic nerve demyelination in rats.
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Affiliation(s)
- Siqi Li
- Eye School of Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 610036, China
| | - Qiuyi Song
- Eye School of Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 610036, China
| | - Bin Wu
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Guanghan Kan
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Fei Wang
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Jiawei Yang
- Eye School of Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 610036, China; Key Laboratory of Sichuan Province Ophthalmopathy Prevention & Cure and Visual Function Protection, Chengdu, Sichuan, 610075, China.
| | - Siquan Zhu
- Eye School of Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 610036, China; Department of Ophthalmology, Beijing Anzhen Hospital, Capital Medical University, Beijing, 100029, China.
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Dai X, Jin X, Ye Q, Huang H, Duo L, Lu C, Bao J, Chen H. Intraperitoneal chromophore injections delay early-onset and rapid retinal cone degeneration in a mouse model of Leber congenital amaurosis. Exp Eye Res 2021; 212:108776. [PMID: 34582935 DOI: 10.1016/j.exer.2021.108776] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 09/04/2021] [Accepted: 09/23/2021] [Indexed: 10/20/2022]
Abstract
Highly expressed in the retinal pigment epithelium (RPE), the RPE-specific 65-kDa (RPE65) enzyme is indispensable to generate 11-cis-retinal (11cRAL), a chromophore for rhodopsin and cone photopigments. RPE65 deficiency can lead to Leber congenital amaurosis type 2 (LCA2), in which the isomerization of photobleached all-trans-retinal into photosensitive 11cRAL is blocked, ultimately causing severe retinal dysfunction and degeneration. The related mouse models, which are constructed through gene knockout or caused by spontaneous mutations, morphologically present with early-onset and rapid retinal cone cells degeneration, including loss of short-wavelength-sensitive cone opsins (S-opsins) and mislocalization of medium-wavelength-sensitive cone opsins (M-opsins). Studies have shown that routine Rpe65 gene replacement therapy, mediated by an adeno-associated virus (AAV) vector, can restore RPE65 protein. However, AAV transfection and Rpe65 transgene expression require at least one to two weeks, and the treatment cannot fully block the early-onset cone degeneration. To determine the feasibility of delaying cone degeneration before gene therapy, we investigated the impact of 11cRAL treatment in an early-age LCA2 retinal degeneration 12 (rd12) mouse model. Similar to human patients, the mouse model carries a spontaneous mutation in the Rpe65 gene, which results in disrupted endogenous 11cRAL regeneration. We found that RPE65 deficiency did not notably affect rodent retinal vessels. Under red light illumination, the rd12 mice were intraperitoneally injected with exogenous 11cRAL from postnatal day (P) 14 to P21. Three days after the last injection, a notable recovery of retinal function was observed using scotopic and photopic electroretinograms. Using optical coherence tomography and histological analyses of the deficient retinas, we found changes in the thickness of the photoreceptor outer segment (OS); this change could be rescued by early 11cRAL treatment. In addition, the treatment notably preserved M- and S-opsins, both of which maintained appropriate localization inside cone cells, as shown by the wild-type mice. In contrast, the age-matched untreated rd12 mice were characterized by retinal S-opsin loss and M-opsin mislocalization from the photoreceptor OS to the inner segment, outer nuclear layer, or outer plexiform layer. Notably, 11cRAL treatment could not maintain retinal function for a long time. Ten days after the last injection, the rod and M-cone electroretinograms significantly decreased, and S-cone responses almost extinguished. Our findings suggest that early 11cRAL treatment is useful for restoring retinal function and rescuing morphology in the rd12 mouse model, and the early-onset and rapid cone degeneration can be delayed before gene therapy.
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Affiliation(s)
- Xufeng Dai
- School of Ophthalmology and Optometry, The Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China; State Key Laboratory of Ophthalmology, Optometry, and Visual Science, 270 Xueyuan Road, Wenzhou, Zhejiang, 325027, China
| | - Xumin Jin
- Laboratory Animal Centre, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Qian Ye
- State Key Laboratory of Ophthalmology, Optometry, and Visual Science, 270 Xueyuan Road, Wenzhou, Zhejiang, 325027, China
| | - Haixiao Huang
- School of Ophthalmology and Optometry, The Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Lan Duo
- School of Ophthalmology and Optometry, The Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China; State Key Laboratory of Ophthalmology, Optometry, and Visual Science, 270 Xueyuan Road, Wenzhou, Zhejiang, 325027, China
| | - Chunjie Lu
- School of Ophthalmology and Optometry, The Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Jinhua Bao
- School of Ophthalmology and Optometry, The Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China; State Key Laboratory of Ophthalmology, Optometry, and Visual Science, 270 Xueyuan Road, Wenzhou, Zhejiang, 325027, China.
| | - Hao Chen
- School of Ophthalmology and Optometry, The Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China; State Key Laboratory of Ophthalmology, Optometry, and Visual Science, 270 Xueyuan Road, Wenzhou, Zhejiang, 325027, China.
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