1
|
Myles WE, McFadden SA. Analytical methods for assessing retinal cell coupling using cut-loading. PLoS One 2022; 17:e0271744. [PMID: 35853039 PMCID: PMC9295955 DOI: 10.1371/journal.pone.0271744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 07/06/2022] [Indexed: 11/25/2022] Open
Abstract
Electrical coupling between retinal neurons contributes to the functional complexity of visual circuits. “Cut-loading” methods allow simultaneous assessment of cell-coupling between multiple retinal cell-types, but existing analysis methods impede direct comparison with gold standard direct dye injection techniques. In the current study, we both improved an existing method and developed two new approaches to address observed limitations. Each method of analysis was applied to cut-loaded dark-adapted Guinea pig retinae (n = 29) to assess coupling strength in the axonless horizontal cell type (‘a-type’, aHCs). Method 1 was an improved version of the standard protocol and described the distance of dye-diffusion (space constant). Method 2 adjusted for the geometric path of dye-transfer through cut-loaded cells and extracted the rate of dye-transfer across gap-junctions in terms of the coupling coefficient (kj). Method 3 measured the diffusion coefficient (De) perpendicular to the cut-axis. Dye transfer was measured after one of five diffusion times (1–20 mins), or with a coupling inhibitor, meclofenamic acid (MFA) (50–500μM after 20 mins diffusion). The standard protocol fits an exponential decay function to the fluorescence profile of a specified retina layer but includes non-specific background fluorescence. This was improved by measuring the fluorescence of individual cell soma and excluding from the fit non-horizontal cells located at the cut-edge (p<0.001) (Method 1). The space constant (Method 1) increased with diffusion time (p<0.01), whereas Methods 2 (p = 0.54) and 3 (p = 0.63) produced consistent results across all diffusion times. Adjusting distance by the mean cell-cell spacing within each tissue reduced the incidence of outliers across all three methods. Method 1 was less sensitive to detecting changes induced by MFA than Methods 2 (p<0.01) and 3 (p<0.01). Although the standard protocol was easily improved (Method 1), Methods 2 and 3 proved more sensitive and generalisable; allowing for detailed assessment of the tracer kinetics between different populations of gap-junction linked cell networks and direct comparison to dye-injection techniques.
Collapse
Affiliation(s)
- William E. Myles
- College of Engineering, Science and Environment, University of Newcastle, Callaghan, NSW, Australia
- * E-mail:
| | - Sally A. McFadden
- College of Engineering, Science and Environment, University of Newcastle, Callaghan, NSW, Australia
| |
Collapse
|
2
|
Cammalleri M, Dal Monte M, Locri F, Pecci V, De Rosa M, Pavone V, Bagnoli P. The urokinase-type plasminogen activator system as drug target in retinitis pigmentosa: New pre-clinical evidence in the rd10 mouse model. J Cell Mol Med 2019; 23:5176-5192. [PMID: 31251468 PMCID: PMC6653070 DOI: 10.1111/jcmm.14391] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 04/05/2019] [Accepted: 05/02/2019] [Indexed: 12/14/2022] Open
Abstract
Retinitis pigmentosa (RP) is characterized by progressive loss of vision due to photoreceptor degeneration leading to secondary inflammation. The urokinase-type plasminogen activator (uPA) system contributes to retinal inflammation, but its role in RP is unknown. In the rd10 mouse model of RP, we addressed this question with the use of the peptide UPARANT designed to interact with the uPA system. UPARANT was systemically administered from post-natal day (PD) 10 to PD30 when its efficacy in RP rescue was investigated using electroretinographic recordings, Western blot and immunocytochemistry. Temporal profile of protein expression in the uPA system was also investigated. UPARANT reduced both Müller cell gliosis and up-regulated levels of inflammatory markers and exerted major anti-apoptotic effects without influencing the autophagy cascade. Rescue from retinal cell degeneration was accompanied by improved retinal function. No scotopic phototransduction was rescued in the UPARANT-treated animals as determined by the kinetic analysis of rod-mediated a-waves and confirmed by rod photoreceptor markers. In contrast, the cone photopic b-wave was recovered and its rescue was confirmed in the whole mounts using cone arrestin antibody. Investigation of the uPA system regulation over RP progression revealed extremely low levels of uPA and its receptor uPAR both of which were recovered by HIF-1α stabilization indicating that HIF-1 regulates the expression of the uPA/uPAR gene in the retina. Ameliorative effects of UPARANT were likely to occur through an inhibitory action on up-regulated activity of the αvβ3 integrin/Rac1 pathway that was suggested as a novel target for the development of therapeutic approaches against RP.
Collapse
Affiliation(s)
| | | | - Filippo Locri
- Department of Biology, University of Pisa, Pisa, Italy
| | - Valeria Pecci
- Department of Biology, University of Pisa, Pisa, Italy
| | - Mario De Rosa
- Department of Experimental Medicine, Second University of Napoli, Napoli, Italy
| | - Vincenzo Pavone
- Department of Chemical Sciences, University of Napoli Federico II, Napoli, Italy
| | - Paola Bagnoli
- Department of Biology, University of Pisa, Pisa, Italy
| |
Collapse
|
3
|
Evaluation of visual function in Royal College of Surgeon rats using a depth perception visual cliff test. Vis Neurosci 2019; 36:E002. [PMID: 30700338 DOI: 10.1017/s095252381800007x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Preserving of vision is the main goal in vision research. The presented research evaluates the preservation of visual function in Royal College of Surgeon (RCS) rats using a depth perception test. Rats were placed on a stage with one side containing an illusory steep drop ("cliff") and another side with a minimal drop ("table"). Latency of stage dismounting and the percentage of rats that set their first foot on the "cliff" side were determined. Nondystrophic Long-Evans (LE) rats were tested as control. Electroretinogram and histology analysis were used to determine retinal function and structure. Four-week-old RCS rats presented a significantly shorter mean latency to dismount the stage compared with 6-week-old rats (mean ± standard error, 13.7 ± 1.68 vs. 20.85 ± 6.5 s, P = 0.018). Longer latencies were recorded as rats aged, reaching 45.72 s in 15-week-old rats (P < 0.00001 compared with 4-week-old rats). All rats at the age of 4 weeks placed their first foot on the table side. By contrast, at the age of 8 weeks, 28.6% rats dismounted on the cliff side and at the age of 10 and 15 weeks, rats randomly dismounted the stage to either table or cliff side. LE rats dismounted the stage faster than 4-week-old RCS rats, but the difference was not statistically significant (7 ± 1.58 s, P = 0.057) and all LE rats dismounted on the table side. The latency to dismount the stage in RCS rats correlated with maximal electroretinogram b-wave under dark and light adaptation (Spearman's rho test = -0.603 and -0.534, respectively, all P < 0.0001), outer nuclear layer thickness (Spearman's rho test = -0.764, P = 0.002), and number of S- and M-cones (Spearman's rho test = -0.763 [P = 0.002], and -0.733 [P = 0.004], respectively). The cliff avoidance test is an objective, quick, and readily available method for the determination of RCS rats' visual function.
Collapse
|
4
|
Tzameret A, Ketter-Katz H, Edelshtain V, Sher I, Corem-Salkmon E, Levy I, Last D, Guez D, Mardor Y, Margel S, Rotenstrich Y. In vivo MRI assessment of bioactive magnetic iron oxide/human serum albumin nanoparticle delivery into the posterior segment of the eye in a rat model of retinal degeneration. J Nanobiotechnology 2019; 17:3. [PMID: 30630490 PMCID: PMC6327435 DOI: 10.1186/s12951-018-0438-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 12/31/2018] [Indexed: 12/17/2022] Open
Abstract
Background Retinal degeneration diseases affect millions of patients worldwide and lead to incurable vision loss. These diseases are caused by pathologies in the retina and underlying choroid, located in the back of the eye. One of the major challenges in the development of treatments for these blinding diseases is the safe and efficient delivery of therapeutics into the back of the eye. Previous studies demonstrated that narrow size distribution core–shell near infra-red fluorescent iron oxide (IO) nanoparticles (NPs) coated with human serum albumin (HSA, IO/HSA NPs) increase the half-life of conjugated therapeutic factors, suggesting they may be used for sustained release of therapeutics. In the present study, the in vivo tracking by MRI and the long term safety of IO/HSA NPs delivery into the suprachoroid of a rat model of retinal degeneration were assessed. Results Twenty-five Royal College of Surgeons (RCS) pigmented rats received suprachoroidal injection of 20-nm IO/HSA NPs into the right eye. The left eye was not injected and used as control. Animals were examined by magnetic resonance imaging (MRI), electroretinogram (ERG) and histology up to 30 weeks following injection. IO/HSA NPs were detected in the back part of the rats’ eyes up to 30 weeks following injection by MRI, and up to 6 weeks by histology. No significant differences in retinal structure and function were observed between injected and non-injected eyes. There was no significant difference in the weight of IO/HSA NP-injected animals compared to non-injected rats. Conclusions MRI could track the nanoparticles in the posterior segment of the injected eyes demonstrating their long-term persistence, and highlighting the possible use of MRI for translational studies in animals and in future clinical studies. Suprachoroidal injection of IO/HSA NPs showed no sign of adverse effects on retinal structure and function in a rat model of retinal degeneration, suggesting that suprachoroidal delivery of IO/HSA NPs is safe and that these NPs may be used in future translational and clinical studies for extended release drug delivery at the back of the eye. Electronic supplementary material The online version of this article (10.1186/s12951-018-0438-y) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Adi Tzameret
- Goldschleger Eye Institute, Sheba Medical Center, 52621, Tel-Hashomer, Israel.,Sackler Faculty of Medicine, Tel-Aviv University, 69978, Tel-Aviv, Israel
| | - Hadas Ketter-Katz
- Goldschleger Eye Institute, Sheba Medical Center, 52621, Tel-Hashomer, Israel
| | - Victoria Edelshtain
- Goldschleger Eye Institute, Sheba Medical Center, 52621, Tel-Hashomer, Israel.,Sackler Faculty of Medicine, Tel-Aviv University, 69978, Tel-Aviv, Israel
| | - Ifat Sher
- Goldschleger Eye Institute, Sheba Medical Center, 52621, Tel-Hashomer, Israel
| | - Enav Corem-Salkmon
- Department of Chemistry, Bar-Ilan Institute of Nanotechnology and Advanced Materials, 52900, Ramat-Gan, Israel
| | - Itay Levy
- Department of Chemistry, Bar-Ilan Institute of Nanotechnology and Advanced Materials, 52900, Ramat-Gan, Israel
| | - David Last
- Advanced Technology Center, Sheba Medical Center, 52621, Ramat-Gan, Israel
| | - David Guez
- Advanced Technology Center, Sheba Medical Center, 52621, Ramat-Gan, Israel
| | - Yael Mardor
- Sackler Faculty of Medicine, Tel-Aviv University, 69978, Tel-Aviv, Israel.,Advanced Technology Center, Sheba Medical Center, 52621, Ramat-Gan, Israel
| | - Shlomo Margel
- Department of Chemistry, Bar-Ilan Institute of Nanotechnology and Advanced Materials, 52900, Ramat-Gan, Israel
| | - Ygal Rotenstrich
- Sackler Faculty of Medicine, Tel-Aviv University, 69978, Tel-Aviv, Israel.
| |
Collapse
|