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Verma-Fuehring R, Dakroub M, Haider MS, Hillenkamp J, Kampik D, Loewen NA. [Continuous Optimisation of Experimental Models - an Example from Glaucoma Research]. Klin Monbl Augenheilkd 2024; 241:69-74. [PMID: 37995716 DOI: 10.1055/a-2069-2443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
BACKGROUND There is a great demand for suitable models to test novel surgical and therapeutic approaches in glaucoma therapy. To address this need and to provide further alternatives to in vivo animal models, we aimed at modifying an established in vitro porcine eye perfusion model. METHODS Two weaknesses of the previously established porcine anterior segment model include media leakage during perfusion and setup disintegration due to mechanical instability. To overcome these, we slightly modified the previously used custom-made perfusion dishes and incorporated new components into the model setup. To prevent fluid leakage, we secured the anterior segments more firmly to the perfusion trays using a compression ring, steel screws, and nuts. Customised mounts were used to stabilise the perfusion dish and pressure transducer as a single unit. The mounts were made of polylactide (PLA) and printed using a 3D printer. RESULTS The use of steel screws and nuts allowed tighter clamping of the anterior segments and prevented medium leakage. Our PLA custom mounts stabilised the entire assembly and facilitated handling during experiments and improved comparability between tested eyes. They also prevented accidental detachment of the pressure transducers, which resulted in more stable pressure curves. Our PLA mounts tolerated incubation temperatures of up to 37 °C and disinfection with enzymatic detergents and 70% ethanol without showing signs of deformation or degradation after four months of regular usage. CONCLUSION Modifications introduced to an established in vitro perfusion model improved its efficacy and reproducibility. Our adjusted model is an example of how many models can be optimised through critical analysis, thereby saving resources and providing reliable results in the long run.
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Affiliation(s)
- Raoul Verma-Fuehring
- Klinik und Poliklinik für Augenheilkunde, Universitätsklinikum Würzburg, Deutschland
| | - Mohamad Dakroub
- Klinik und Poliklinik für Augenheilkunde, Universitätsklinikum Würzburg, Deutschland
| | - Malik Salman Haider
- Klinik und Poliklinik für Augenheilkunde, Universitätsklinikum Würzburg, Deutschland
| | - Jost Hillenkamp
- Klinik und Poliklinik für Augenheilkunde, Universitätsklinikum Würzburg, Deutschland
| | - Daniel Kampik
- Klinik und Poliklinik für Augenheilkunde, Universitätsklinikum Würzburg, Deutschland
| | - Nils Axel Loewen
- Augenheilkunde, ARTEMIS Augen- und Laserzentrum Frankfurt, Deutschland
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Mikula ER, Raksi F, Ahmed II, Sharma M, Holland G, Khazaeinezhad R, Bradford S, Jester JV, Juhasz T. Femtosecond Laser Trabeculotomy in Perfused Human Cadaver Anterior Segments: A Novel, Noninvasive Approach to Glaucoma Treatment. Transl Vis Sci Technol 2022; 11:28. [PMID: 35333286 PMCID: PMC8963660 DOI: 10.1167/tvst.11.3.28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Purpose The purpose of this study was to investigate femtosecond laser trabeculotomy (FLT) in a clinically relevant manner (i.e., delivering the surgical laser beam through the cornea of the intact, human anterior segment to create channels from the anterior chamber into the Schlemm's canal) and to investigate the effect of this treatment on intraocular pressure in perfused human anterior segments. Methods Perfused human anterior segments (15 eyes) received either FLT treatment (n = 8) or a sham-treatment (n = 7). Intraocular pressure (IOP) in the perfused samples was recorded before and after treatment. Spectral domain optical coherence tomography, second harmonic generation imaging, and transmission electron microscopy were used to investigate the FLT channels. Results The FLT group (n = 7, 1 eye excluded) had a statistically significant reduction in mean IOP of 20.2% from baseline after treatment (5.06 ± 1.46 mm Hg to 4.04 ± 1.63 mm Hg; P < 0.0005), whereas the control group (n = 7) remained statistically unchanged (7.72 ± 3.45 mm Hg to 7.78 ± 3.51 mm Hg; P < 0.71). Imaging confirmed that the channels traversed the entire trabecular meshwork into the Schlemm's canal. Conclusions This study has provided the first direct evidence supporting the feasibility of clinically applicable, noninvasive femtosecond laser trabeculotomy for the treatment of glaucoma. Various imaging modalities revealed minimal collateral damage to adjacent issues. Translational Relevance This work demonstrates noninvasive femtosecond laser trabeculotomy in a laboratory setting that is clinically relevant.
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Affiliation(s)
- Eric R Mikula
- Department of Ophthalmology, University of California, Irvine, Irvine, CA, USA.,ViaLase Inc., Aliso Viejo, CA, USA
| | | | - Iqbal Ike Ahmed
- University of Toronto, Toronto, ON, Canada.,University of Utah, Salt Lake City, UT, USA
| | | | | | | | - Samantha Bradford
- Department of Ophthalmology, University of California, Irvine, Irvine, CA, USA
| | - James V Jester
- Department of Ophthalmology, University of California, Irvine, Irvine, CA, USA.,Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, USA
| | - Tibor Juhasz
- Department of Ophthalmology, University of California, Irvine, Irvine, CA, USA.,Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, USA.,ViaLase Inc., Aliso Viejo, CA, USA
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3
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Mikula E, Holland G, Srass H, Suarez C, Jester JV, Juhasz T. Intraocular Pressure Reduction by Femtosecond Laser Created Trabecular Channels in Perfused Human Anterior Segments. Transl Vis Sci Technol 2021; 10:22. [PMID: 34406341 PMCID: PMC8374973 DOI: 10.1167/tvst.10.9.22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose This study investigated the initial feasibility of using femtosecond laser trabeculotomy (FLT) to create open channels through the trabecular meshwork into Schlemm's canal to lower intraocular pressure (IOP) in a perfused anterior segment model. Methods Human anterior segments (12 eyes) were assigned to either treatment (n = 6) or sham treatment (n = 6) groups. Both groups were perfused until a baseline IOP was recorded upon which a direct FLT treatment or a sham treatment was administered. IOP was recorded before and after the treatment. Spectral domain optical coherence tomography and second harmonic generation imaging we used to investigate the FLT channels. Results In the FLT group, there was a significant mean decrease in the IOP of 22% compared with the pre-FLT IOP (7.13 ± 2.95 mm Hg to 5.34 ± 1.62 mm Hg; P < 0.05). In the control group, the post-sham IOP remained relatively unchanged compared with the pre-sham IOP (6.39 ± 3.69 mm Hg to 6.67 ± 4.12 mm Hg). Conclusions The results of this study indicate that FLT treatment can significantly decrease the IOP in a perfusion model and may provide a potential noninvasive treatment option for primary open angle glaucoma. Translational Relevance Investigating the use of femtosecond lasers for photodisrupting the trabecular meshwork can lead to a clinically relevant alternative to current glaucoma procedures.
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Affiliation(s)
- Eric Mikula
- Department of Ophthalmology, University of California, Irvine, Irvine, CA, USA.,ViaLase Inc., Aliso Viejo, CA, USA
| | | | | | | | - James V Jester
- Department of Ophthalmology, University of California, Irvine, Irvine, CA, USA.,Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, USA
| | - Tibor Juhasz
- Department of Ophthalmology, University of California, Irvine, Irvine, CA, USA.,ViaLase Inc., Aliso Viejo, CA, USA.,Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, USA
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4
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Snider EJ, Cornell LE, Gross BM, Zamora DO, Boice EN. Assessment of Commercial Off-the-Shelf Tissue Adhesives for Sealing Military-Relevant Corneal Perforation Injuries. Mil Med 2021; 187:e1346-e1353. [PMID: 33959769 DOI: 10.1093/milmed/usab184] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 04/15/2021] [Accepted: 04/27/2021] [Indexed: 11/12/2022] Open
Abstract
INTRODUCTION Open-globe ocular injuries have increased in frequency in recent combat operations due to increased use of explosive weaponry. Unfortunately, open-globe injuries have one of the worst visual outcomes for the injured warfighter, often resulting in permanent loss of vision. To improve visual recovery, injuries need to be stabilized quickly following trauma, in order to restore intraocular pressure and create a watertight seal. Here, we assess four off-the-shelf (OTS), commercially available tissue adhesives for their ability to seal military-relevant corneal perforation injuries (CPIs). MATERIALS AND METHODS Adhesives were assessed using an anterior segment inflation platform and a previously developed high-speed benchtop corneal puncture model, to create injuries in porcine eyes. After injury, adhesives were applied and injury stabilization was assessed by measuring outflow rate, ocular compliance, and burst pressure, followed by histological analysis. RESULTS Tegaderm dressings and Dermabond skin adhesive most successfully sealed injuries in preliminary testing. Across a range of injury sizes and shapes, Tegaderm performed well in smaller injury sizes, less than 2 mm in diameter, but inadequately sealed large or complex injuries. Dermabond created a watertight seal capable of maintaining ocular tissue at physiological intraocular pressure for almost all injury shapes and sizes. However, application of the adhesive was inconsistent. Histologically, after removal of the Dermabond skin adhesive, the corneal epithelium was removed and oftentimes the epithelium surface penetrated into the wound and was adhered to inner stromal tissue. CONCLUSIONS Dermabond can stabilize a wide range of CPIs; however, application is variable, which may adversely impact the corneal tissue. Without addressing these limitations, no OTS adhesive tested herein can be directly translated to CPIs. This highlights the need for development of a biomaterial product to stabilize these injuries without causing ocular damage upon removal, thus improving the poor vision prognosis for the injured warfighter.
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Affiliation(s)
- Eric J Snider
- Department of Sensory Trauma, United States Army Institute of Surgical Research, Fort Sam Houston, TX 78234, USA
| | - Lauren E Cornell
- Department of Sensory Trauma, United States Army Institute of Surgical Research, Fort Sam Houston, TX 78234, USA
| | - Brandon M Gross
- Department of Sensory Trauma, United States Army Institute of Surgical Research, Fort Sam Houston, TX 78234, USA
| | - David O Zamora
- Department of Sensory Trauma, United States Army Institute of Surgical Research, Fort Sam Houston, TX 78234, USA
| | - Emily N Boice
- Department of Sensory Trauma, United States Army Institute of Surgical Research, Fort Sam Houston, TX 78234, USA
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Snider EJ, Boice EN, Gross B, Butler JJ, Zamora DO. Characterization of an anterior segment organ culture model for open globe injuries. Sci Rep 2021; 11:8546. [PMID: 33879808 PMCID: PMC8058041 DOI: 10.1038/s41598-021-87910-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 03/30/2021] [Indexed: 12/05/2022] Open
Abstract
Open-globe injuries have poor visual outcomes and have increased in frequency. The current standard of care is inadequate, and a therapeutic is needed to stabilize the injury until an ophthalmic specialist is reached. Unfortunately, current models or test platforms for open-globe injuries are insufficient. Here, we develop and characterize an open-globe injury model using an anterior segment organ-culture platform that allows therapeutic assessment for up to 72 h post-injury. Anterior segments maintained in organ culture were kept at physiological intraocular pressure throughout, and puncture injuries were created using a novel pneumatic-powered system. This system can create high-speed, military-relevant injuries up to 4.5 mm in diameter through the cornea. From intraocular pressure readings, we confirmed a loss of pressure across the 72 h after open-globe injury. Proof-of-concept studies with a Dermabond tissue adhesive were performed to show how this model system could track therapeutic performance for 72 h. Overall, the organ-culture platform was found to be a suitable next step towards modeling open-globe injuries and assessing wound closure over the critical 72 h post-injury. With improved models such as this, novel biomaterial therapeutics development can be accelerated, improving care, and, thus, improving the prognosis for the patients.
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Affiliation(s)
- Eric J Snider
- Department of Sensory Trauma, United States Army Institute of Surgical Research, Fort Sam Houston, TX, 78234, USA.
| | - Emily N Boice
- Department of Sensory Trauma, United States Army Institute of Surgical Research, Fort Sam Houston, TX, 78234, USA
| | - Brandon Gross
- Department of Sensory Trauma, United States Army Institute of Surgical Research, Fort Sam Houston, TX, 78234, USA
| | - Jacinque J Butler
- Department of Sensory Trauma, United States Army Institute of Surgical Research, Fort Sam Houston, TX, 78234, USA
| | - David O Zamora
- Department of Sensory Trauma, United States Army Institute of Surgical Research, Fort Sam Houston, TX, 78234, USA
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Snider EJ, Hardie BA, Li Y, Gao K, Splaine F, Kim RK, Vannatta RT, Read AT, Ethier CR. A Porcine Organ-Culture Glaucoma Model Mimicking Trabecular Meshwork Damage Using Oxidative Stress. Invest Ophthalmol Vis Sci 2021; 62:18. [PMID: 33704361 PMCID: PMC7960799 DOI: 10.1167/iovs.62.3.18] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Purpose Re-cellularization of the trabecular meshwork (TM) using stem cells is a potential novel treatment for ocular hypertension associated with glaucoma. To assess the therapeutic efficacy of this approach, improved in vivo and ex vivo models of TM pathophysiology are needed. Here, we investigate whether oxidative stress, induced by hydrogen peroxide (H2O2), can model glaucomatous ocular hypertension in the readily available porcine anterior segment organ culture model. Methods The impact of H2O2 on TM cell viability and function was first evaluated in vitro using primary porcine TM cells. Oxidative stress was then induced by H2O2 infusion into perfused porcine anterior segments. Trabecular meshwork function was assessed by tracking matrix metalloproteinase (MMP) activity and the ability of the preparation to maintain intraocular pressure (IOP) homeostasis after a flow challenge (doubled fluid infusion rate). Finally, the TM was evaluated histologically. Results H2O2 treatment resulted in a titratable reduction in cellularity across multiple primary TM cell donor strains. In organ culture preparations, H2O2-treated eyes showed impaired IOP homeostasis (i.e., IOPs stabilized at higher levels after a flow challenge vs. control eyes). This result was consistent with reduced MMP activity and TM cellularity; however, damage to the TM microstructure was not histologically evident in anterior segments receiving H2O2. Conclusions Titrated H2O2 infusion resulted in TM cellular dysfunction without destruction of TM structure. Thus, this porcine organ culture model offers a useful platform for assessing trabecular meshwork therapies to treat ocular hypertension associated with glaucoma.
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Affiliation(s)
- Eric J Snider
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
| | - Becky A Hardie
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
| | - Yinglin Li
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
| | - Kristin Gao
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
| | - Fiona Splaine
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
| | - R Kijoon Kim
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
| | - R Taylor Vannatta
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
| | - A Thomas Read
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
| | - C Ross Ethier
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
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Haribalaganesh R, Gowri Priya C, Sharmila R, Krishnadas S, Muthukkaruppan V, Willoughby CE, Senthilkumari S. Assessment of differential intraocular pressure response to dexamethasone treatment in perfusion cultured Indian cadaveric eyes. Sci Rep 2021; 11:605. [PMID: 33436790 PMCID: PMC7804010 DOI: 10.1038/s41598-020-80112-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 12/08/2020] [Indexed: 11/29/2022] Open
Abstract
The purpose of the present study was to assess the differential intraocular pressure response (IOP) to dexamethasone (DEX) treatment at two dose levels (100 or 500 nM) in perfusion cultured Indian cadaveric eyes to investigate glucocorticoid (GC) responsiveness. In a human organ-cultured anterior segment (HOCAS) set-up, the eye pressure was monitored for every 24 h post DEX infusion (100 or 500 nM) or 0.1% ethanol treatment for 7 days after baseline stabilization. The expression of DEX-inducible proteins such as myocilin and fibronectin in HOCAS-TM tissues was assessed by immunostaining. Elevated IOP was observed in 6/16 eyes [Mean ± SEM (mΔIOP): 15.50 ± 1.96 mmHg; 37.5% responders] and 3/15 eyes (Mean ± SEM mΔIOP: 10 ± 0.84 mmHg; 20% responders) in 100 nM and 500 nM dose groups respectively. Elevated IOP in GC responder eyes was substantiated with a significant increase in myocilin (11.8-fold; p = 0.0002) and fibronectin (eightfold; p = 0.04) expression as compared to vehicle-treated eyes by immunofluorescence analysis. This is the first study reporting the GC responsiveness in Indian cadaveric eyes. The observed GC response rate was comparable with the previous studies and hence, this model will enable us to investigate the relationship between differential gene expression and individual GC responsiveness in our population.
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Affiliation(s)
- Ravinarayanan Haribalaganesh
- Department of Ocular Pharmacology, Aravind Medical Research Foundation, #1, Anna Nagar, Madurai, Tamilnadu, 625020, India
| | - Chidambaranathan Gowri Priya
- Department of Immunology and Stem Cell Biology, Aravind Medical Research Foundation, #1, Anna Nagar, Madurai, 625020, India
| | | | - Subbaiah Krishnadas
- Glaucoma Clinic, Aravind Eye Hospital, #1, Anna Nagar, Madurai, 625020, India
| | - Veerappan Muthukkaruppan
- Department of Immunology and Stem Cell Biology, Aravind Medical Research Foundation, #1, Anna Nagar, Madurai, 625020, India
| | - Colin E Willoughby
- Genomic Medicine Group, Biomedical Sciences Research Institute, Ulster University, Coleraine, Northern Ireland, UK
| | - Srinivasan Senthilkumari
- Department of Ocular Pharmacology, Aravind Medical Research Foundation, #1, Anna Nagar, Madurai, Tamilnadu, 625020, India.
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Loewen RT, Waxman S, Wang C, Atta S, Chen S, Watkins SC, Watson AM, Loewen NA. 3D-Reconstruction of the human conventional outflow system by ribbon scanning confocal microscopy. PLoS One 2020; 15:e0232833. [PMID: 32421732 PMCID: PMC7233539 DOI: 10.1371/journal.pone.0232833] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Accepted: 04/22/2020] [Indexed: 11/19/2022] Open
Abstract
PURPOSE The risk for glaucoma is driven by the microanatomy and function of the anterior segment. We performed a computation-intense, high-resolution, full-thickness ribbon-scanning confocal microscopy (RSCM) of the outflow tract of two human eyes. We hypothesized this would reveal important species differences when compared to existing data of porcine eyes, an animal that does not spontaneously develop glaucoma. METHODS After perfusing two human octogenarian eyes with lectin-fluorophore conjugate and optical clearance with benzyl alcohol benzyl benzoate (BABB), anterior segments were scanned by RSCM and reconstructed in 3D for whole-specimen rendering. Morphometric analyses of the outflow tract were performed for the trabecular meshwork (TM), limbal, and perilimbal outflow structures and compared to existing porcine data. RESULTS RSCM provided high-resolution data for IMARIS-based surface reconstruction of outflow tract structures in 3D. Different from porcine eyes with an abundance of highly interconnected, narrow, and short collector channels (CCs), human eyes demonstrated fewer CCs which had a 1.5x greater cross-sectional area (CSA) and 2.6x greater length. Proximal CC openings at the level of Schlemm's canal (SC) had a 1.3x larger CSA than distal openings into the scleral vascular plexus (SVP). CCs were 10.2x smaller in volume than the receiving SVP vessels. Axenfeld loops, projections of the long ciliary nerve, were also visualized. CONCLUSION In this high-resolution, volumetric RSCM analysis, human eyes had far fewer outflow tract vessels than porcine eyes. Human CCs spanned several clock-hours and were larger than in porcine eyes. These species differences may point to factors downstream of the TM that increase our vulnerability to glaucoma.
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Affiliation(s)
- Ralitsa T. Loewen
- Department of Ophthalmology, University of Würzburg, Würzburg, Germany
| | - Susannah Waxman
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Chao Wang
- Department of Ophthalmology, University of Würzburg, Würzburg, Germany
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Cellular Biology, Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Sarah Atta
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Si Chen
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Simon C. Watkins
- Department of Cellular Biology, Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Alan M. Watson
- Department of Cellular Biology, Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Nils A. Loewen
- Department of Ophthalmology, University of Würzburg, Würzburg, Germany
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Shear Stress in Schlemm's Canal as a Sensor of Intraocular Pressure. Sci Rep 2020; 10:5804. [PMID: 32242066 PMCID: PMC7118084 DOI: 10.1038/s41598-020-62730-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 03/13/2020] [Indexed: 11/23/2022] Open
Abstract
Elevated intraocular pressure (IOP) narrows Schlemm’s canal (SC), theoretically increasing luminal shear stress. Using engineered adenoviruses containing a functional fragment of the shear-responsive endothelial nitric oxide synthase (eNOS) promoter, we tested effects of shear stress and elevated flow rate on reporter expression in vitro and ex vivo. Cultured human umbilical vein endothelial cells (HUVECs) and SC cells were transduced with adenovirus containing eNOS promoter driving secreted alkaline phosphatase (SEAP) or green fluorescent protein (GFP) and subjected to shear stress. In parallel, human anterior segments were perfused under controlled flow. After delivering adenoviruses to the SC lumen by retroperfusion, the flow rate in one anterior segment of pair was increased to double pressure. In response to high shear stress, HUVECs and SC cells expressed more SEAP and GFP than control. Similarly, human anterior segments perfused at higher flow rates released significantly more nitrites and SEAP into perfusion effluent, and SC cells expressed increased GFP near collector channel ostia compared to control. These data establish that engineered adenoviruses have the capacity to quantify and localize shear stress experienced by endothelial cells. This is the first in situ demonstration of shear-mediated SC mechanobiology as a key IOP-sensing mechanism necessary for IOP homeostasis.
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10
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Development and Characterization of a Benchtop Corneal Puncture Injury Model. Sci Rep 2020; 10:4218. [PMID: 32144320 PMCID: PMC7060308 DOI: 10.1038/s41598-020-61079-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 02/11/2020] [Indexed: 12/13/2022] Open
Abstract
During recent military operations, eye-related injuries have risen in frequency due to increased use of explosive weaponry which often result in corneal puncture injuries. These have one of the poorest visual outcomes for wounded soldiers, often resulting in blindness due to the large variations in injury shape, size, and severity. As a result, improved therapeutics are needed which can stabilize the injury site and promote wound healing. Unfortunately, current corneal puncture injury models are not capable of producing irregularly shaped, large, high-speed injuries as seen on the battlefield, making relevant therapeutic development challenging. Here, we present a benchtop corneal puncture injury model for use with enucleated eyes that utilizes a high-speed solenoid device suitable for creating military-relevant injuries. We first established system baselines and ocular performance metrics, standardizing the different aspects of the benchtop model to ensure consistent results and properly account for tissue variability. The benchtop model was evaluated with corneal puncture injury objects up to 4.2 mm in diameter which generated intraocular pressure levels exceeding 1500 mmHg. Overall, the created benchtop model provides an initial platform for better characterizing corneal puncture injuries as seen in a military relevant clinical setting and a realistic approach for assessing potential therapeutics.
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11
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Bogarin T, Saraswathy S, Akiyama G, Xie X, Weinreb RN, Zheng J, Huang AS. Cellular and cytoskeletal alterations of scleral fibroblasts in response to glucocorticoid steroids. Exp Eye Res 2019; 187:107774. [PMID: 31449795 PMCID: PMC6759408 DOI: 10.1016/j.exer.2019.107774] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 08/22/2019] [Accepted: 08/22/2019] [Indexed: 11/16/2022]
Abstract
Steroid-induced ocular hypertension can be seen even after trabecular meshwork (TM) bypass/ablation. Thus, the purpose was to investigate steroid-response in cells distal to the TM by using primary scleral fibroblasts. Primary scleral cell cultures were generated using mid-depth scleral wedges from human donor corneo-scleral rims (n = 5) after corneal transplantation. Cells were treated with dexamethasone (DEX; 100 nM) and compared to media (MED)/vehicle (DMSO) controls. Cell size, shape, and migration were studied using the IncuCyte Live-Cell Analysis System. Cytoskeleton was compared using Alexa Fluor-568 Phalloidin and senescence tested by evaluating beta-galactosidase. Western blot comparison was performed for α-SMA, FKBP-51, fibronectin, phospho-myosin light chain, and myocilin. Scleral fibroblasts upregulated FKBP-51 in response to DEX indicating the existence of steroid-responsive pathways. Compared to controls, DEX-treated cells proliferated slower (~50%; p < 0.01-0.02), grew larger (~1.3-fold; p < 0.001), and migrated less (p = 0.01-0.006). Alexa Fluor 568 Phalloidin actin stress fiber labeling was more diffuse in DEX-treated cells (p = 0.001-0.004). DEX-treated cells showed more senescence compared to controls (~1.7-fold; p = 0.01-0.02). However, DEX-treated cells did not show increased cross-linked actin network formation or elevated myocilin/fibronectin/α-SMA/phospho-myosin light chain protein expression. For all parameters, MED- and DMSO-treated control cells were not significantly different. Primary scleral fibroblasts, grown from tissue collected immediately distal to the TM, demonstrated scleral-response behaviors that were similar to, but not identical with, classic TM steroid-response. Further study is needed to understand how these scleral cellular alterations may contribute to steroid-response IOP elevation after TM bypass/ablation surgery.
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Affiliation(s)
- Thania Bogarin
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Sindhu Saraswathy
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Goichi Akiyama
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Xiaobin Xie
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Eye Hospital of China Academy of Chinese Medical Sciences, Beijing, China
| | - Robert N Weinreb
- Hamilton Glaucoma Center, Shiley Eye Institute, and the Viterbi Family Department of Ophthalmology University of California, San Diego, CA, USA
| | - Jie Zheng
- Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Alex S Huang
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
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Kubelick KP, Snider EJ, Ethier CR, Emelianov S. Photoacoustic properties of anterior ocular tissues. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-11. [PMID: 31115200 PMCID: PMC6992976 DOI: 10.1117/1.jbo.24.5.056004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 04/19/2019] [Indexed: 05/21/2023]
Abstract
Clinical imaging techniques for the anterior segment of the eye provide excellent anatomical information, but molecular imaging techniques are lacking. Molecular photoacoustic imaging is one option to address this need, but implementation requires use of contrast agents to distinguish molecular targets from background photoacoustic signals. Contrast agents are typically selected based on a priori knowledge of photoacoustic properties of tissues. However, photoacoustic properties of anterior ocular tissues have not been studied yet. Herein, anterior segment anatomy and corresponding photoacoustic signals were analyzed in brown and blue porcine eyes ex vivo. Measured photoacoustic spectra were compared to known optical absorption spectra of endogenous chromophores. In general, experimentally measured photoacoustic spectra matched expectations based on absorption spectra of endogenous chromophores reported in the literature, and similar photoacoustic spectra were observed in blue and brown porcine eyes. However, unique light-tissue interactions at the iris modified photoacoustic signals from melanin. Finally, we demonstrated how the measured PA spectra established herein can be used for one application of molecular PA imaging, detecting photoacoustically labeled stem cells in the anterior segment for glaucoma treatment.
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Affiliation(s)
- Kelsey P. Kubelick
- Georgia Institute of Technology and Emory University School of Medicine, Wallace H. Coulter Department of Biomedical Engineering, Atlanta, Georgia, United States
| | - Eric J. Snider
- Georgia Institute of Technology and Emory University School of Medicine, Wallace H. Coulter Department of Biomedical Engineering, Atlanta, Georgia, United States
| | - C. Ross Ethier
- Georgia Institute of Technology and Emory University School of Medicine, Wallace H. Coulter Department of Biomedical Engineering, Atlanta, Georgia, United States
| | - Stanislav Emelianov
- Georgia Institute of Technology and Emory University School of Medicine, Wallace H. Coulter Department of Biomedical Engineering, Atlanta, Georgia, United States
- Georgia Institute of Technology, School of Electrical and Computer Engineering, Atlanta, Georgia, United States
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13
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Januschowski K, Schnichels S, Hurst J, Hohenadl C, Reither C, Rickmann A, Pohl L, Bartz-Schmidt KU, Spitzer MS. Ex vivo biophysical characterization of a hydrogel-based artificial vitreous substitute. PLoS One 2019; 14:e0209217. [PMID: 30615640 PMCID: PMC6322733 DOI: 10.1371/journal.pone.0209217] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 11/30/2018] [Indexed: 01/31/2023] Open
Abstract
Purpose To characterize the biophysical properties of an artificial vitreous body substitute (VBS), which consists of a biocompatible, cross-linked, hyaluronic acid (HA)-based hydrogel, by analysing the VBS’s influence on intraocular pressure (IOP) and retinal integrity in distinct ex vivo eye models in order to evaluate the its potential for in vivo biocompatibility testing. Methods Pig eyes were obtained immediately postmortem, and VBS was injected after core-vitrectomy. IOP was followed for 24 h (n = 5). VBS influence on retinal integrity was investigated using isolated bovine retinas superfused with an oxygen saturated nutrient solution. An electroretinogram (ERG) was recorded on explanted bovine retinae using silver/silver chloride electrodes; after application of VBS for 2 min, a washout period of 70 min was employed. The percentage of a-and b-wave reduction at the end of the washout phase was compared to baseline values (n = 5). Data were calculated throughout as the mean and the standard deviation. qRT-PCR (Bax/Bcl–2-ratio, GFAP- and PGP9.5-levels) or western blot analysis was used to test for toxicity of Princess Volume after 24 h (and β-3 tubulin with GAPDH as a control gene). Significance was estimated by Student´s t-test; p ≤0.05 was considered to be statistically significant. Results The IOP increased non-significantly by 10% after 24 h. Short-term biocompatibility testing using isolated superfused bovine retinas showed neither significant reductions of the b-wave nor the a-wave amplitudes (b-wave reduction 14.2%, p>0.05; a-wave reduction 23.9%, p>0.05). qRT-PCR and western blot analysis did not reveal significant toxicity after 24 h. Conclusions The manufactured HA-based hydrogel showed highly favourable biophysical characteristics in the explored ex vivo models, justifying in vivo studies enabling the assessment of biocompatibility.
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Affiliation(s)
- Kai Januschowski
- Eye Clinic Sulzbach-Saar, Sulzbach-Saar, Germany
- University Eye Clinic Tübingen, Centre for Ophthalmology, Tübingen, Germany
- * E-mail:
| | - Sven Schnichels
- University Eye Clinic Tübingen, Centre for Ophthalmology, Tübingen, Germany
| | - José Hurst
- University Eye Clinic Tübingen, Centre for Ophthalmology, Tübingen, Germany
| | | | | | | | - Lisa Pohl
- University Eye Clinic Tübingen, Centre for Ophthalmology, Tübingen, Germany
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14
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Snider EJ, Kubelick KP, Tweed K, Kim RK, Li Y, Gao K, Read AT, Emelianov S, Ethier CR. Improving Stem Cell Delivery to the Trabecular Meshwork Using Magnetic Nanoparticles. Sci Rep 2018; 8:12251. [PMID: 30115953 PMCID: PMC6095892 DOI: 10.1038/s41598-018-30834-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 08/07/2018] [Indexed: 02/02/2023] Open
Abstract
Glaucoma is a major cause of blindness and is frequently associated with elevated intraocular pressure. The trabecular meshwork (TM), the tissue that primarily regulates intraocular pressure, is known to have reduced cellularity in glaucoma. Thus, stem cells, if properly delivered to the TM, may offer a novel therapeutic option for intraocular pressure control in glaucoma patients. For this purpose, targeted delivery of stem cells to the TM is desired. Here, we used magnetic nanoparticles (Prussian blue nanocubes [PBNCs]) to label mesenchymal stem cells and to magnetically steer them to the TM following injection into the eye's anterior chamber. PBNC-labeled stem cells showed increased delivery to the TM vs. unlabeled cells after only 15-minute exposure to a magnetic field. Further, PBNC-labeled mesenchymal stem cells could be delivered to the entire circumference of the TM, which was not possible without magnetic steering. PBNCs did not affect mesenchymal stem cell viability or multipotency. We conclude that this labeling approach allows for targeted, relatively high-efficiency delivery of stem cells to the TM in clinically translatable time-scales, which are necessary steps towards regenerative medicine therapies for control of ocular hypertension in glaucoma patients.
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Affiliation(s)
- E J Snider
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - K P Kubelick
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - K Tweed
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - R K Kim
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Y Li
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - K Gao
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - A T Read
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - S Emelianov
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia
| | - C R Ethier
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia.
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15
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Aktas Z, Rao H, Slauson SR, Gabelt BT, Larsen IV, Sheridan RTC, Herrnberger L, Tamm ER, Kaufman PL, Brandt CR. Proteasome Inhibition Increases the Efficiency of Lentiviral Vector-Mediated Transduction of Trabecular Meshwork. Invest Ophthalmol Vis Sci 2018; 59:298-310. [PMID: 29340644 PMCID: PMC5961099 DOI: 10.1167/iovs.17-22074] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Purpose To determine if proteasome inhibition using MG132 increased the efficiency of FIV vector–mediated transduction in human trabecular meshwork (TM)-1 cells and monkey organ-cultured anterior segments (MOCAS). Methods TM-1 cells were pretreated for 1 hour with 0.5% dimethyl sulfoxide (DMSO; vehicle control) or 5 to 50 μM MG132 and transduced with FIV.GFP (green fluorescent protein)– or FIV.mCherry-expressing vector at a multiplicity of transduction (MOT) of 20. At 24 hours, cells were fixed and stained with antibodies for GFP, and positive cells were counted, manually or by fluorescence-activated cell sorting (FACS). Cells transduced with FIV.GFP particles alone were used as controls. The effect of 20 μM MG132 treatment on high- and low-dose (2 × 107 and 0.8 × 107 transducing units [TU], respectively) FIV.GFP transduction with or without MG132 was also evaluated in MOCAS using fluorescence microscopy. Vector genome equivalents in cells and tissues were quantified by quantitative (q)PCR on DNA. Results In the MG132 treatment groups, there was a significant dose-dependent increase in the percentage of transduced cells at all concentrations tested. Vector genome equivalents were also increased in TM-1 cells treated with MG132. Increased FIV.GFP expression in the TM was also observed in MOCAS treated with 20 μM MG132 and the high dose of vector. Vector genome equivalents were also significantly increased in the MOCAS tissues. Increased transduction was not seen with the low dose of virus. Conclusions Proteasome inhibition increased the transduction efficiency of FIV particles in TM-1 cells and MOCAS and may be a useful adjunct for delivery of therapeutic genes to the TM by lentiviral vectors.
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Affiliation(s)
- Zeynep Aktas
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States.,Department of Ophthalmology, Gazi University Medical Faculty, Ankara, Turkey
| | - Hongyu Rao
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States
| | - Sarah R Slauson
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States
| | - B'Ann T Gabelt
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States
| | - Inna V Larsen
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States
| | - Rachael T C Sheridan
- UW Carbone Cancer Center Flow Cytometry Laboratory, University of Wisconsin-Madison, Madison, Wisconsin, United States
| | - Leonie Herrnberger
- Institute of Human Anatomy, University of Regensburg, Regensburg, Germany
| | - Ernst R Tamm
- Institute of Human Anatomy, University of Regensburg, Regensburg, Germany
| | - Paul L Kaufman
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States.,McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, Wisconsin, United States
| | - Curtis R Brandt
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States.,McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, Wisconsin, United States.,Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, United States
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16
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McDonnell F, Dismuke WM, Overby DR, Stamer WD. Pharmacological regulation of outflow resistance distal to Schlemm's canal. Am J Physiol Cell Physiol 2018; 315:C44-C51. [PMID: 29631366 DOI: 10.1152/ajpcell.00024.2018] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The trabecular meshwork (TM) and Schlemm's canal generate the majority of outflow resistance; however, the distal regions of the conventional outflow pathway account for 25-50% of total resistance. Sections of distal vessels are surrounded by α-smooth muscle actin-containing cells, indicating that they may be vasoregulated. This study examined the effect of a potent vasodilator, nitric oxide (NO), and its physiological antagonist, endothelin-1 (ET-1), on the regulation of outflow resistance in the distal regions of the conventional outflow pathway. Using a physiological model of the conventional outflow pathway, human and porcine anterior segments were perfused in organ culture under constant flow conditions, while intrachamber pressure was continually monitored. For porcine anterior segments, a stable baseline outflow facility with TM intact was first achieved before anterior segments were removed and a trabeculotomy was performed. For human anterior segments, a trabeculotomy was immediately performed. In human anterior segments, 100 nM ET-1 significantly decreased distal outflow facility from 0.49 ± 0.26 to 0.31 ± 0.18 (mean ± SD) µl·min-1·mmHg, P < 0.01. Perfusion with 100 µM diethylenetriamine-NO in the presence of 1 nM ET-1 immediately reversed ET-1 effects, significantly increasing distal outflow facility to 0.54 ± 0.35 µl·min-1·mmHg, P = 0.01. Similar results were obtained in porcine anterior segment experiments. Therefore, data show a dynamic range of resistance generation by distal vessels in both the human and the porcine conventional outflow pathways. Interestingly, maximal contraction of vessels in the distal outflow tract of trabeculotomized eyes generated resistance very near physiological levels for both species having an intact TM.
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Affiliation(s)
- Fiona McDonnell
- Department of Ophthalmology, Duke University , Durham, North Carolina
| | - W Michael Dismuke
- Department of Ophthalmology, Duke University , Durham, North Carolina
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London , London , United Kingdom
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University , Durham, North Carolina.,Department of Biomedical Engineering, Duke University , Durham, North Carolina
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17
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Ebner M, Mariacher S, Hurst J, Szurman P, Schnichels S, Spitzer MS, Januschowski K. Characterization of a Standardized Ex-vivo Porcine Model to Assess Short Term Intraocular Pressure Changes and Trabecular Meshwork Vitality After Pars Plana Vitrectomy with Different Silicone Oil and BSS Tamponades. Curr Eye Res 2017; 42:1130-1135. [DOI: 10.1080/02713683.2017.1297461] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Martina Ebner
- Knappschaft Eye Clinic Sulzbach, Knappschaft Hospital Saar, Sulzbach, Germany
| | - Siegfried Mariacher
- Knappschaft Eye Clinic Sulzbach, Knappschaft Hospital Saar, Sulzbach, Germany
| | - José Hurst
- University Eye Hospital Tuebingen, Center for Ophthalmology, Tuebingen, Germany
| | - Peter Szurman
- Knappschaft Eye Clinic Sulzbach, Knappschaft Hospital Saar, Sulzbach, Germany
- University Eye Hospital Tuebingen, Center for Ophthalmology, Tuebingen, Germany
| | - Sven Schnichels
- University Eye Hospital Tuebingen, Center for Ophthalmology, Tuebingen, Germany
| | - Martin S. Spitzer
- University Eye Hospital Tuebingen, Center for Ophthalmology, Tuebingen, Germany
| | - Kai Januschowski
- Knappschaft Eye Clinic Sulzbach, Knappschaft Hospital Saar, Sulzbach, Germany
- University Eye Hospital Tuebingen, Center for Ophthalmology, Tuebingen, Germany
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18
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Robinson J, Okoro E, Ezuedu C, Bush L, Opere CA, Ohia SE, Njie-Mbye YF. Effects of Hydrogen Sulfide-Releasing Compounds on Aqueous Humor Outflow Facility in Porcine Ocular Anterior Segments, Ex Vivo. J Ocul Pharmacol Ther 2017; 33:91-97. [PMID: 28099049 DOI: 10.1089/jop.2016.0037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
PURPOSE To investigate the pharmacological actions of hydrogen sulfide (H2S)-releasing compounds l-cysteine and sodium hydrosulfide (NaHS) on aqueous humor (AH) outflow facility in porcine ocular anterior segment. METHODS Porcine ocular anterior segments were perfused with Dulbecco's modified Eagle's medium at a constant pressure of 7.35 mmHg. After stable outflow baseline, explants were exposed to NaHS or l-cysteine. The increase in outflow generated by the H2S-releasing compounds was measured in the absence and presence of inhibitor of H2S biosynthesis (aminooxyacetic acid; AOAA), blocker of KATP channels (glibenclamide), and inhibitor of adenylyl cyclase (SQ 22536). Hematoxylin and eosin (H&E) staining was used to assess trabecular meshwork (TM) morphology. RESULTS l-cysteine elicited a concentration-dependent increase in AH outflow facility, reaching maximal effect at 100 nM (150.6% ± 17.2% of basal level). This increase in outflow induced by l-cysteine was significantly (P < 0.001) antagonized by AOAA (30 μM) and glibenclamide (100 μM). AOAA and glibenclamide had no significant action on baseline outflow, whereas SQ 22536 (100 μM) increased outflow for only an hour. In addition, NaHS produced a concentration-dependent increase in AH outflow, with a maximal effect at 10 μM (151.4% ± 22.9% of basal level). Likewise, the increase in outflow caused by NaHS was significantly (P < 0.04) blocked by glibenclamide and SQ 22536. H&E staining revealed that l-cysteine or NaHS did not alter TM conformation. CONCLUSION H2S-releasing compounds can increase outflow facility in porcine ocular anterior segment. The stimulatory action of these compounds on outflow is mediated, in part by endogenously produced H2S, KATP channels, and adenylyl cyclase.
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Affiliation(s)
- Jenaye Robinson
- 1 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas
| | - Esther Okoro
- 1 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas
| | - Chinoso Ezuedu
- 1 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas
| | - Leah Bush
- 1 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas
| | - Catherine A Opere
- 2 Department of Pharmacy Sciences, School of Pharmacy and Health Professions, Creighton University , Omaha, Nebraska
| | - Sunny E Ohia
- 1 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas
| | - Ya Fatou Njie-Mbye
- 1 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas
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Rybkin I, Gerometta R, Fridman G, Candia O, Danias J. Model systems for the study of steroid-induced IOP elevation. Exp Eye Res 2016; 158:51-58. [PMID: 27450911 DOI: 10.1016/j.exer.2016.07.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Revised: 06/24/2016] [Accepted: 07/19/2016] [Indexed: 12/16/2022]
Abstract
Steroid-induced IOP elevation affects a significant number of patients. It results from a decrease in outflow facility of the aqueous humor. To understand the pathophysiology of this condition a number of model systems have been created. These include ex-vivo cell and organ cultures as well as in-vivo animal models in organisms ranging from rodents to primates. These model systems can be used to investigate specific aspects of steroid-induced IOP elevation. This brief review summarizes the strengths and limitations of the various model systems and provides examples of where these systems have been successfully used to advance our understanding of steroid-induced IOP elevation.
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Affiliation(s)
- Ilya Rybkin
- Department of Cell Biology, SUNY Downstate, NY, USA
| | - Rosana Gerometta
- Departamento de Oftalmologia, Facultad de Medicina, Universidad Nacional del Nordeste, Corrientes, Argentina; Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | | | - Oscar Candia
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - John Danias
- Department of Cell Biology, SUNY Downstate, NY, USA; Department of Ophthalmology, SUNY Downstate, NY, USA.
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Abu-Hassan DW, Li X, Ryan EI, Acott TS, Kelley MJ. Induced pluripotent stem cells restore function in a human cell loss model of open-angle glaucoma. Stem Cells 2015; 33:751-61. [PMID: 25377070 PMCID: PMC4359625 DOI: 10.1002/stem.1885] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 09/18/2014] [Accepted: 10/11/2014] [Indexed: 11/06/2022]
Abstract
Normally, trabecular meshwork (TM) and Schlemm's canal inner wall endothelial cells within the aqueous humor outflow pathway maintain intraocular pressure within a narrow safe range. Elevation in intraocular pressure, because of the loss of homeostatic regulation by these outflow pathway cells, is the primary risk factor for vision loss due to glaucomatous optic neuropathy. A notable feature associated with glaucoma is outflow pathway cell loss. Using controlled cell loss in ex vivo perfused human outflow pathway organ culture, we developed compelling experimental evidence that this level of cell loss compromises intraocular pressure homeostatic function. This function was restored by repopulation of the model with fresh TM cells. We then differentiated induced pluripotent stem cells (iPSCs) and used them to repopulate this cell depletion model. These differentiated cells (TM-like iPSCs) became similar to TM cells in both morphology and expression patterns. When transplanted, they were able to fully restore intraocular pressure homeostatic function. This successful transplantation of TM-like iPSCs establishes the conceptual feasibility of using autologous stem cells to restore intraocular pressure regulatory function in open-angle glaucoma patients, providing a novel alternative treatment option. Stem Cells2015;33:751–761
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Affiliation(s)
- Diala W Abu-Hassan
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA; Department of Biochemistry & Molecular Biology, Oregon Health & Science University, Portland, Oregon, USA; Department of Biochemistry & Physiology, University of Jordan, Amman, Jordan
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21
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Chu ER, Gonzalez JM, Tan JCH. Tissue-based imaging model of human trabecular meshwork. J Ocul Pharmacol Ther 2014; 30:191-201. [PMID: 24517246 PMCID: PMC3991999 DOI: 10.1089/jop.2013.0190] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 12/13/2013] [Indexed: 12/20/2022] Open
Abstract
We have developed a tissue-based model of the human trabecular meshwork (TM) using viable postmortem corneoscleral donor tissue. Two-photon microscopy is used to optically section and image deep in the tissue to analyze cells and extracellular matrix (ECM) within the original three-dimensional (3D) environment of the TM. Multimodal techniques, including autofluorescence (AF), second harmonic generation (SHG), intravital dye fluorescence, and epifluorescence, are combined to provide unique views of the tissue at the cellular and subcellular level. SHG and AF imaging are non-invasive tissue imaging techniques with potential for clinical application, which can be modeled in the system. We describe the following in the tissue-based model: analysis of live cellularity to determine tissue viability; characteristics of live cells based on intravital labeling; features and composition of the TM's structural ECM; localization of specific ECM proteins to regions such as basement membrane; in situ induction and expression of tissue markers characteristic of cultured TM cells relevant to glaucoma; analysis of TM actin and pharmacological effects; in situ visualization of TM, inner wall endothelium, and Schlemm's canal; and application of 3D reconstruction, modeling, and quantitative analysis to the TM. The human model represents a cost-effective use of valuable and scarce yet available human tissue that allows unique cell biology, pharmacology, and translational studies of the TM.
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Affiliation(s)
- Edward R Chu
- Department of Ophthalmology, Keck School of Medicine, University of Southern California , Los Angeles, California
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22
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Abu-Hassan DW, Acott TS, Kelley MJ. The Trabecular Meshwork: A Basic Review of Form and Function. ACTA ACUST UNITED AC 2014; 2. [PMID: 25356439 DOI: 10.13188/2334-2838.1000017] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Diala W Abu-Hassan
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, Oregon, USA
| | - Ted S Acott
- Department of Biochemistry & Molecular Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Mary J Kelley
- Department of Biochemistry & Physiology, University of Jordan, Amman, Jordan
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23
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Gonzalez JM, Heur M, Tan JCH. Two-photon immunofluorescence characterization of the trabecular meshwork in situ. Invest Ophthalmol Vis Sci 2012; 53:3395-404. [PMID: 22531697 DOI: 10.1167/iovs.11-8570] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To develop an in situ model to study biological responses and glaucoma pathology in the human trabecular meshwork (TM). Characteristic TM cell- and glaucoma-associated markers were localized in situ in relation to the tissue's autofluorescent structural extracellular matrix (ECM) by two-photon excitation fluorescence optical sectioning (TPEF). METHODS Human donor corneoscleral (CS) tissue containing the intact aqueous drainage tract was incubated with dexamethasone (Dex) or TGF-β1, and immunostained for epifluorescence (EF) microscopy with antibodies to myocilin and alpha smooth muscle (α-SMA). Separate specimens were labeled for Type-IV collagen and fibronectin. Nuclei were stained with Hoechst 33342. Multimodal TPEF was used to visualize EF, intravital dyes, and autofluorescence (AF) in situ. Three-dimensional (3D) localization of fluorescence within the TM was analyzed using reconstruction software. RESULTS Autofluorescent beams, perforated sheets, and fibers, consistent with the uveal (UV), CS, and juxtacanalicular (JCT) meshwork, respectively, were captured at different depths of the TM. Type-IV collagen EF distinctly outlined the AF beams in a location consistent with basement membrane. Fibronectin EF showed a diffuse reticular pattern throughout the TM. TGF-β1-induced α-SMA expression, which was distributed perinuclearly in cells among autofluorescent structures. Dex-induced myocilin expression had both cytosolic and extracellular distributions. CONCLUSIONS The authors have localized markers that are characteristic of TM cells and relevant to glaucoma pathogenesis in situ using multimodal TPEF without conventional histological embedding and sectioning. Protein expression was inducible in situ and could be analyzed with respect to cells and the ECM within the 3D environment of the human TM.
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Affiliation(s)
- Jose M Gonzalez
- Doheny Eye Institute and Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA
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24
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Tan JCH, Gonzalez JM, Hamm-Alvarez S, Song J. In situ autofluorescence visualization of human trabecular meshwork structure. Invest Ophthalmol Vis Sci 2012; 53:2080-8. [PMID: 22410566 DOI: 10.1167/iovs.11-8141] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To characterize the three-dimensional (3-D) structure of the human trabecular meshwork (TM) by two-photon excited (TPEF) autofluorescence (AF) and optical sectioning without conventional histologic embedding and sectioning. METHODS Viable human ex vivo explants of the anterior chamber angle containing the aqueous humor drainage tissue in situ were imaged by TPEF to localize AF and Hoechst 33342 nuclear fluorescence. An autofluorescent marker in Schlemm's Canal (SC) aided SC situ visualization. En face and orthogonal views of the TM were generated. RESULTS In the innermost uveal TM, AF signals outlined an intricate 3-D network of fine branching beams with large openings between the beams. In the adjacent corneoscleral TM, beams were thicker and coalesced as plate-like structures with pore-like openings. Linear and coiled AF fibers were visible on the background AF of beams. Deeper, in the external TM, this organization changed to fine fiber arrays orientated in the tissue's longitudinal axis, reminiscent of the cribriform plexus of the juxtacanalicular TM (JCT). In the outermost JCT, AF of fine fibers was sparse, then undetectable as optical sections approached the inner wall of SC. Cell nuclei were closely associated with the TM structural extracellular matrix. CONCLUSIONS We have used TPEF and optical sectioning to exploit AF as a useful method to visualize the structure of the human conventional aqueous drainage pathway in situ. Ancillary nuclear staining allowed cell association with the AF structures to be seen. This approach revealed a unique 3-D perspective of the TM that is consistent with known TM structural characteristics.
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Affiliation(s)
- James C H Tan
- Doheny Eye Institute and Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA
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Fuchshofer R, Tamm ER. The role of TGF-β in the pathogenesis of primary open-angle glaucoma. Cell Tissue Res 2011; 347:279-90. [PMID: 22101332 DOI: 10.1007/s00441-011-1274-7] [Citation(s) in RCA: 200] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 10/24/2011] [Indexed: 01/08/2023]
Abstract
Transforming growth factor-β2 (TGF-β2) is found in increasing amounts in aqueous humor and reactive optic nerve astrocytes of patients with primary open-angle glaucoma (POAG), a major cause of blindness worldwide. The available data strongly indicate that TGF-β2 is a key player contributing to the structural changes in the extracellular matrix (ECM) of the trabecular meshwork and optic nerve head as characteristically seen in POAG. The changes involve an induction in the expression of various ECM molecules and are remarkably similar in trabecular meshwork cells and optic nerve head astrocytes. The ECM changes in the trabecular meshwork most probably play a role in the increase of aqueous humor outflow resistance causing higher intraocular pressure (IOP). In the optic nerve head, TGF-β2-induced changes might contribute to deformation of the optic nerve axons causing impairment of axonal transport and neurotrophic supply and leading to their continuous degeneration. The increase in IOP further adds mechanical stress and strain to optic nerve axons and accelerates degenerative changes. In addition, high IOP might induce the expression of activated TGF-β1 in trabecular meshwork cells and optic nerve head astrocytes; this again might significantly lead to the progress of axonal degeneration. The action of TGF-β2 in POAG is largely mediated through the connective tissue growth factor, whereas the activities of TGF-β1 and -β2 are modulated by the blocking effects of bone morphogenetic protein-4 (BMP-4) and BMP-7, by gremlin that inhibits BMP signaling and by several species of microRNAs.
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Affiliation(s)
- Rudolf Fuchshofer
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
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Dismuke WM, Ellis DZ. Activation of the BK(Ca) channel increases outflow facility and decreases trabecular meshwork cell volume. J Ocul Pharmacol Ther 2009; 25:309-14. [PMID: 19552602 DOI: 10.1089/jop.2008.0133] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
PURPOSE Inhibition of the BK(Ca) channel attenuated the nitric oxide-induced increase in outflow facility and decrease in trabecular meshwork (TM) cell volume suggesting the involvement of the BK(Ca) channel in TM cell function. This study examined the effects of activation of the BK(Ca) channel on outflow facility and TM cell volume and determined if the effects of NO and BK(Ca) channel activation on TM cell volume were additive. METHODS Porcine eyes were used to measure outflow facility using the anterior segment organ culture perfusion system. Cell volume was measured using Calcein AM fluorescent dye, detected by confocal microscopy, and quantified using NIH ImageJ software. RESULTS NS1619 increased outflow facility 86% over baseline. Additionally, there was a concentration-dependent decrease in TM cell volume in response to NS1619, which was abolished by iberiotoxin (IBTX). While NS1619 alone and DETA-NO alone decreased TM cell volume, together their effects were not additive. The time course for NS1619-induced increases in outflow facility correlated with the time course for NS1619-induced decreases in cell volume. CONCLUSIONS BK(Ca) channel activation increases outflow facility and decreases cell volume suggesting that K(+) efflux regulates TM cell function.
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Affiliation(s)
- William M Dismuke
- Department of Pharmacodynamics, University of Florida, 1600 SW Archer Road, Gainesville, FL 32610, USA
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Resch ZT, Fautsch MP. Glaucoma-associated myocilin: a better understanding but much more to learn. Exp Eye Res 2009; 88:704-12. [PMID: 18804106 PMCID: PMC2682697 DOI: 10.1016/j.exer.2008.08.011] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 08/18/2008] [Accepted: 08/19/2008] [Indexed: 01/20/2023]
Abstract
Over a decade has passed since myocilin was identified as the first gene linked to early and late-onset primary open-angle glaucoma. During this time, considerable effort has been put forth to understand the functional role myocilin has in normal and glaucomatous eyes. Myocilin is expressed in many ocular and non-ocular tissues, is found in both intracellular and extracellular spaces, and has been linked to elevations in intraocular pressure. Mutations in the myocilin gene that have been associated with glaucoma appear to confer a gain-of-functional activity rather than loss of function. Unfortunately, what the normal function of myocilin is and how alterations in the function can confer a glaucoma phenotype have yet to be elucidated. We will review the current understanding of myocilin with special emphasis on the structural makeup of the myocilin gene and protein, its possible physiological roles internal and external to ocular cells, the regulation of intraocular pressure as evidenced through the use of perfusion culture systems and animal models, and as a causative agent in some forms of glaucoma.
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Affiliation(s)
- Zachary T Resch
- Department of Ophthalmology, Mayo Clinic, Rochester, MN 55905, USA.
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Patel SV, Bachman LA, Hann CR, Bahler CK, Fautsch MP. Human corneal endothelial cell transplantation in a human ex vivo model. Invest Ophthalmol Vis Sci 2009; 50:2123-31. [PMID: 19136716 DOI: 10.1167/iovs.08-2653] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
PURPOSE To determine the effects of incorporating superparamagnetic microspheres (SPMs) into cultured human corneal endothelial cells (HCECs) and to describe preliminary experiments of HCEC transplantation, facilitated by SPMs and an external magnetic field, in a human anterior segment ex vivo model. METHODS HCECs were cultured as monolayers and incorporated with magnetite oxide SPMs (900, 300, and 100 nm) at different concentrations. Cell viability, migration toward a magnetic field, and light transmittance were measured after incorporation of the SPMs. HCEC transplantation into the eyes of human recipients was investigated by subjecting anterior segments in organ culture to an external magnetic field. Light and electron microscopy were used to assess HCEC attachment to corneal stroma. RESULTS SPMs were incorporated into the cytoplasm of HCECs after overnight incubation. None of the SPMs affected the short-term viability of cultured HCECs (P > 0.14, n = 6) or their light transmittance (P > 0.06, n = 5), although there was a trend toward decreased transmittance with the higher concentration of 900-nm SPMs. Cell migration toward a magnetic field was higher for HCECs with incorporated SPMs than for HCECs without SPMs (P < or = 0.01, n = 6), with dose-response relationships evident for the 300- and 100-nm SPMs. SPMs facilitated the attachment of HCECs to the corneal stroma in the human anterior segment model with minimal change in intracameral (intraocular) pressure. CONCLUSIONS SPMs facilitate migration of HCECs toward a magnetic source and attachment of cells to the corneal stroma without affecting cell viability or light transmittance. The human anterior segment model can be used to study HCEC transplantation.
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Affiliation(s)
- Sanjay V Patel
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota 55905, USA.
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Aga M, Bradley JM, Keller KE, Kelley MJ, Acott TS. Specialized podosome- or invadopodia-like structures (PILS) for focal trabecular meshwork extracellular matrix turnover. Invest Ophthalmol Vis Sci 2008; 49:5353-65. [PMID: 18641286 DOI: 10.1167/iovs.07-1666] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
PURPOSE There are distinctive areas of colocalization of matrix metalloproteinase (MMP)-2 and -14 on trabecular meshwork (TM) cells that resemble podosomes or invadopodia. Studies were conducted to determine whether TM cells exhibit podosome- or invadopodia-like structures (PILS) and whether they produce focal extracellular matrix (ECM) turnover. METHODS Porcine and human TM cells and perfused anterior segment organ cultures were studied. Localization of PILS components on TM cells and in sections from anterior segments was determined by immunohistochemistry and confocal microscopy. Cells were grown on type I collagen labeled with fluorescein isothiocyanate (FITC) for degradation analysis. Confocal time lapse images were taken of labeled TM cells on FITC-collagen. RESULTS Immunostaining for MMP-2, MMP-14, and the typical PILS components cortactin, caldesmon, alpha-actinin, N-WASP, Arp-3, and cdc42 colocalized on these distinctive structures. Integrin-alphaV and -beta1, fibronectin, and versican colocalized with PILS components. TM cells on FITC-conjugated collagen developed focal regions of degradation. Time-lapse imaging showed dramatic and controlled movement of TM cell processes during this ECM degradation and fragment internalization. MMP-2, MMP-14, and cortactin colocalized at regions that appear to be PILS on cells within the outflow pathway in sections of human anterior segments. CONCLUSIONS TM cells exhibit areas where PILS components colocalize with MMP-2 and -14. Similar structures are found in sections, suggesting that PILS occur in situ in the outflow pathway. The collagen degradation suggests that PILS may serve as focal sites for targeted ECM turnover, an event linked to modifications of aqueous outflow resistance and intraocular pressure homeostasis.
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Affiliation(s)
- Mini Aga
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon 97239-4197, USA
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Aquaporin-1 expression and conventional aqueous outflow in human eyes. Exp Eye Res 2008; 87:349-55. [PMID: 18657536 DOI: 10.1016/j.exer.2008.06.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Revised: 06/03/2008] [Accepted: 06/30/2008] [Indexed: 11/22/2022]
Abstract
Aquaporin channels facilitate the enhanced permeability of secretory and absorptive tissues to water. In the conventional drainage tract, aquaporin-1 is expressed but its contribution to outflow facility is unknown. The purpose of the present study was to determine the effect of elevated aquaporin-1 expression by cells of the human conventional drainage pathway on outflow facility. Using 13 pairs of human anterior segments in organ culture, we modified aquaporin-1 protein expression in outflow cells using adenovirus encoding human aquaporin-1. Contralateral anterior segments served as controls and were transduced with adenovirus encoding beta-galactosidase. By confocal immunofluorescence microscopy, we observed that inner trabecular meshwork cells from anterior segments exposed to adenovirus (via injection into the inlet tubing during perfusion) had increased aquaporin-1 protein expression compared to endogenous levels. In contrast, elevation of aquaporin-1 protein in outer meshwork cells (juxtacanalicular region) and Schlemm's canal required transduction of adenovirus into anterior segments using retroperfusion via episcleral veins. Regardless of exposure route, outflow facility of experimental segments was not different than control. Specifically, overexpression of aquaporin-1 in the inner meshwork resulted in an average facility change of -2.0+/-9.2%, while overexpression of aquaporin-1 in the resistance-generating region changed outflow facility by -3.2+/-11.2%. Taken together, these results indicate that a transcellular pathway, mediated by aquaporin-1, does not contribute significantly to bulk outflow through the conventional aqueous outflow tract of human eyes.
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Dismuke WM, Mbadugha CC, Ellis DZ. NO-induced regulation of human trabecular meshwork cell volume and aqueous humor outflow facility involve the BKCa ion channel. Am J Physiol Cell Physiol 2008; 294:C1378-86. [PMID: 18385281 DOI: 10.1152/ajpcell.00363.2007] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitric oxide (NO) donors decrease intraocular pressure (IOP) by increasing aqueous outflow facility in the trabecular meshwork (TM) and/or Schlemm's canal. However, the cellular mechanisms are unknown. Cellular mechanisms known to regulate outflow facility include changes in cell volume and cellular contractility. In this study, we investigated the effects of NO donors on outflow facility and NO-induced effects on TM cell volume. We tested the involvement of soluble guanylate cyclase (sGC), cGMP, PKG, and the large-conductance Ca2+-activated K+ (BKCa) channel using inhibitors and activators. Cell volume was measured using calcein AM fluorescent dye, detected by confocal microscopy, and quantified using NIH ImageJ software. An anterior segment organ perfusion system measured outflow facility. NO increased outflow facility in porcine eye anterior segments (0.4884-1.3956 microl.min(-1).mmHg(-1)) over baseline (0.2373-0.5220 microl.min(-1).mmHg(-1)) within 10 min of drug application. These NO-induced increases in outflow facility were inhibited by the the BKCa channel inhibitor IBTX. Exposure of TM cells to NO resulted in a 10% decrease in cell volume, and these decreases were abolished by the sGC inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one and IBTX, suggesting the involvement of sGC and K+ eflux, respectively. NO-induced decreases in cell volume were mimicked by 8-Br-cGMP and abolished by the PKG inhibitor (RP)-8-Br-PET-cGMP-S, suggesting the involvement cGMP and PKG. Additionally, the time course for NO-induced decreases in TM cell volume correlated with NO-induced increases in outflow facility, suggesting that the NO-induced alterations in cell volume may influence outflow facility.
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Affiliation(s)
- William M Dismuke
- University of Florida, College of Pharmacy, Department of Pharmacodynamics, Gainesville, FL 32610, USA
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32
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Ramos RF, Stamer WD. Effects of cyclic intraocular pressure on conventional outflow facility. Invest Ophthalmol Vis Sci 2008; 49:275-81. [PMID: 18172103 DOI: 10.1167/iovs.07-0863] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
PURPOSE In vivo, biomechanical stress plays an important role in tissue physiology and pathology, affecting cell and tissue behavior. Even though conventional outflow tissues are constantly exposed to dynamic changes in intraocular pressure, effects of such biomechanical stressors on outflow function have not been analyzed. The purpose of the present study was to determine the effect(s) of ocular pulse on conventional outflow facility in perfused anterior segments. METHODS The anterior segment perfusion model was used to investigate the impact of ocular pulsation on human and porcine outflow facility. To determine tissue viability of human anterior segments, three complementary techniques (postperfusion morphology and cell density of outflow tissues plus central corneal thickness measurements over time of perfusion) were used. RESULTS A consistent decrease in outflow facility was observed in response to cyclic intraocular pressure in both porcine (-29.96% +/- 6.56; P = 0.009) and human (-27.65% +/- 8.26; P = 0.010) perfused anterior segments. Viability data showed no significant difference between control and experimental anterior segments, with respect to postperfusion histologic evaluations (P = 0.227) or change in central corneal thickness over time (P = 0.289). In contrast, the cellularity of the trabecular meshwork in experimental (cyclically pulsed) anterior segments (333.86 +/- 22.15 nuclei/field of view) was greater than in the control eyes (290.47 +/- 17.60, P = 0.05). CONCLUSIONS Decreased outflow facility in cyclically pulsed anterior segments is not a function of cell or tissue damage, but rather is an active response of the conventional outflow tissues to a biomechanical stimulus. In fact, the observation of increased cellularity in tissues exposed to cyclic stress suggests a physiological benefit of mechanical stress to outflow cells in organ culture.
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Affiliation(s)
- Renata F Ramos
- Biomedical Engineering Graduate Program, University of Arizona, Tucson, AZ 85711, USA
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Bahler CK, Howell KG, Hann CR, Fautsch MP, Johnson DH. Prostaglandins increase trabecular meshwork outflow facility in cultured human anterior segments. Am J Ophthalmol 2008; 145:114-9. [PMID: 17988642 DOI: 10.1016/j.ajo.2007.09.001] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Revised: 08/24/2007] [Accepted: 09/01/2007] [Indexed: 11/28/2022]
Abstract
PURPOSE To determine the effect of latanoprost free acid and prostaglandin E1 (PGE1) on outflow facility in cultured human anterior segments. Clinical studies find prostaglandin treatment increases uveoscleral outflow, but do not agree whether trabecular outflow increases. Cultured anterior segments eliminate the uveoscleral pathway and enable a direct assessment of trabecular outflow. DESIGN Laboratory investigation. METHODS One anterior segment of an eye pair was placed in perfusion organ culture and received a continuous infusion of drug while the fellow anterior segment received vehicle. Histologic changes were assessed. Zymography and Western blots were used to analyze matrix metalloprotease (MMP) activity. Scleral hydraulic conductivities were measured. RESULTS Latanoprost significantly increased outflow facility (67% +/- 11% vs control 6% +/- 10%, P < .001). Facility changes occurred within one hour of receiving drug, reaching a new baseline by 24 hours. Facility changes were reversible, requiring about 48 hours to return to pre-drug values. PGE1 caused less facility change (13% +/- 17% vs control 1% +/- 11%, P = .02). Prostaglandin treated anterior segments had regions of focal detachment and loss of Schlemm canal endothelial cells, with loss of extracellular matrix underlying some areas. MMPs were not consistently increased in Western blots, zymography, or immunohistochemistry. Scleral hydraulic conductivity increased, but not enough to account for total facility increase. CONCLUSIONS Prostaglandins increase outflow facility in perfusion organ culture of human anterior segments. MMP activity was not consistently increased, and scleral hydraulic conductivity was not increased sufficiently to account for total facility increase. The histologic changes suggest a direct trabecular meshwork effect.
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Wan Z, Woodward DF, Cornell CL, Fliri HG, Martos JL, Pettit SN, Wang JW, Kharlamb AB, Wheeler LA, Garst ME, Landsverk KJ, Struble CS, Stamer WD. Bimatoprost, prostamide activity, and conventional drainage. Invest Ophthalmol Vis Sci 2007; 48:4107-15. [PMID: 17724194 PMCID: PMC2680422 DOI: 10.1167/iovs.07-0080] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Despite structural similarity with prostaglandin F(2 alpha), the ocular hypotensive agent bimatoprost (Lumigan; Allergan, Inc., Irvine, CA) shows unique pharmacology in vitro and functional activity in vivo. Unfortunately, the precise mechanisms that underlie bimatoprost's distinctive impact on aqueous humor dynamics are unclear. The purpose of the present study was to investigate the effects of bimatoprost and a novel prostamide-selective antagonist AGN 211334 on human conventional drainage. METHODS Two model systems were used to test the consequences of bimatoprost and/or AGN 211334 treatment on conventional drainage. Human anterior segments in organ culture were perfused at a constant flow rate of 2.5 microL/min while pressure was recorded continuously. After stable baseline facilities were established, segments were treated with drug(s), and pressure was monitored for an additional 3 days. In parallel, the drugs' effects on hydraulic conductivity of human trabecular meshwork (TM) cell monolayers were evaluated. Pharmacological properties of AGN 211334 were characterized in isolated feline iris preparations in organ culture and heterologously expressed G-protein-coupled receptors were examined in vitro. RESULTS Bimatoprost increased outflow facility by an average of 40% +/- 10% within 48 hours of treatment (n = 10, P < 0.001). Preincubation or coincubation with AGN 211334 significantly blunted bimatoprost's effects by 95% or 43%, respectively. Similar results were obtained in cell culture experiments in which bimatoprost increased hydraulic conductivity of TM cell monolayers by 78% +/- 25%. Pretreatment with AGN 211334 completely blocked bimatoprost's effects, while coincubation decreased its effects on average by 74%. In both models, AGN 211334 alone significantly decreased fluid flux across trabecular tissues and cells. CONCLUSIONS The findings indicate that bimatoprost interacts with a prostamide receptor in the trabecular meshwork to increase outflow facility.
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Affiliation(s)
- Zhou Wan
- Department of Ophthalmology and Vision Science, University of Arizona, Tucson, AZ 85711, USA
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Daniel Stamer W, Chan DWH, Ross Ethier C. Targeted gene transfer to Schlemm's canal by retroperfusion. Exp Eye Res 2007; 84:843-9. [PMID: 17359976 PMCID: PMC1892596 DOI: 10.1016/j.exer.2007.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2006] [Revised: 12/14/2006] [Accepted: 01/04/2007] [Indexed: 11/26/2022]
Abstract
The goal of the present study was to specifically modify protein expression in the resistance-generating region of the conventional outflow pathway, namely the inner wall of Schlemm's canal (SC) and the juxtacanalicular region of the trabecular meshwork, in perfused human anterior segments. Anterior segments from human cadaveric eyes were prepared for organ culture using standard techniques and were perfused at constant flow while recording pressure. After reaching a stable outflow facility within physiological limits, forward perfusion was stopped and a fluid-tight fence encircling the limbus was installed and filled with media containing an adenovirus encoding the lacZ reporter gene (either 2 x 10(6) or 6 x 10(6)PFU/ml). With the limbus submerged, pressure inside the chamber was lowered to -1 mmHg to facilitate reverse perfusion of virus into SC ("retroperfusion"). After 30-60 min at zero pressure (with some mixing), forward perfusion was restarted and continued for 5-7 days, after which anterior segments were fixed and processed for visualization of lacZ activity. Retroperfusion of nine anterior segments with adenovirus encoding a reporter gene did not appreciably alter baseline outflow facility (0.27+/-0.05 versus 0.29+/-0.08 microl/min per mmHg post-retroperfusion). Gross examination of outflow tissues showed focal distribution of lacZ activity around the circumference of SC, presumably near collector channels. In segments that were sequentially tilted during retroperfusion, the distribution of lacZ activity appeared more uniform. Sagittal histological sections showed lacZ activity in all portions of the conventional drainage tract, particularly cells in the resistance-generating region. Taken together, the results demonstrate that candidate protein expression by cells in the resistance-generating region of the conventional drainage pathway can be specifically modified by retroperfusion of adenovirus and examined for effects on outflow facility.
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Affiliation(s)
- W Daniel Stamer
- Department of Ophthalmology, The University of Arizona, Tucson, AZ, USA.
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36
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Wan Z, Brigatti L, Ranger-Moore J, Ethier CR, Stamer WD. Rate of change in central corneal thickness: a viability indicator for conventional drainage tissues in organ culture. Exp Eye Res 2006; 82:1086-93. [PMID: 16466713 DOI: 10.1016/j.exer.2005.10.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2005] [Revised: 10/18/2005] [Accepted: 10/31/2005] [Indexed: 11/15/2022]
Abstract
Organ culture of human anterior segments is a powerful tool for understanding trabecular meshwork biology. However, data from a significant percentage of cultured anterior segments are unusable because tissues fail to meet quality control requirements, such as having adequate trabecular meshwork histology. The purpose of the present study was to evaluate a novel, real time method for assessing the viability of conventional drainage tissues in the human anterior segment perfusion model. Twenty-two human anterior segments were perfusion cultured using standard techniques for one week while measuring outflow facility and central corneal thickness (CCT). After perfusion-fixation, toludine blue-stained histological sections of drainage tissues from all four quadrants of each anterior segment were graded and endothelial cell nuclei from cornea centers were stained with 4',6-diamidino-2-phenylindole and counted. We found that most anterior segments with a stable outflow facility had a CCT that decreased over time, while anterior segments with an unstable outflow facility had CCT measurements that failed to decrease over time (P<0.01). When comparing CCT measurements to histological appearance of outflow tissues, we found that in 11/11 cases, anterior segments with an acceptable histological score had a negative CCT slope (P<0.01). Conversely in 3/4 instances, anterior segments with an unacceptable histological score had a positive CCT slope. Lastly, we observed a significant relationship between CCT measurements and corneal endothelial density (P<0.01). Thus, the simple procedure of measuring CCT during anterior segment perfusion provides a second useful measure to assess the viability of the anterior segment during the perfusion process.
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Affiliation(s)
- Z Wan
- Department of Ophthalmology and Vision Science, The University of Arizona, Tucson, AZ 85711, USA
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Loewen N, Fautsch MP, Peretz M, Bahler CK, Cameron JD, Johnson DH, Poeschla EM. Genetic modification of human trabecular meshwork with lentiviral vectors. Hum Gene Ther 2001; 12:2109-19. [PMID: 11747600 DOI: 10.1089/10430340152677449] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Glaucoma, a group of optic neuropathies, is the leading cause of irreversible blindness. Neuronal apoptosis in glaucoma is primarily associated with high intraocular pressure caused by chronically impaired outflow of aqueous humor through the trabecular meshwork, a reticulum of mitotically inactive endothelial-like cells located in the angle of the anterior chamber. Anatomic, genetic, and expression profiling data suggest the possibility of using gene transfer to treat glaucomatous intraocular pressure dysregulation, but this approach will require stable genetic modification of the differentiated aqueous outflow tract. We injected transducing unit-normalized preparations of either of two lentiviral vectors or an oncoretroviral vector as a single bolus into the aqueous circulation of cultured human donor eyes, under perfusion conditions that mimicked natural anterior chamber flow and maintained viability ex vivo. Reporter gene expression was assessed in trabecular meshwork from 3 to 16 days after infusion of 1.0 x 10(8) transducing units of each vector. The oncoretroviral vector failed to transduce the trabecular meshwork. In contrast, feline immunodeficiency virus and human immunodeficiency virus vectors produced efficient, localized transduction of the trabecular meshwork in situ. The results demonstrate that lentiviral vectors permit efficient genetic modification of the human trabecular meshwork when delivered via the afferent aqueous circulation, a clinically accessible route. In addition, controlled comparisons in this study establish that feline and human immunodeficiency virus vectors are equivalently efficacious in delivering genes to this terminally differentiated human tissue.
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Affiliation(s)
- N Loewen
- Molecular Medicine Program, Mayo Clinic, Rochester, MN 55905, USA
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Borrás T, Rowlette LL, Erzurum SC, Epstein DL. Adenoviral reporter gene transfer to the human trabecular meshwork does not alter aqueous humor outflow. Relevance for potential gene therapy of glaucoma. Gene Ther 1999; 6:515-24. [PMID: 10476211 DOI: 10.1038/sj.gt.3300860] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Obstruction of the aqueous humor outflow from the anterior chamber of the eye leads to an elevation of intraocular pressure in glaucoma, the second major cause of blindness worldwide. Our goal is to be able to modulate aqueous humor outflow resistance by gene transfer to the cells of the trabecular meshwork (TM). We have previously shown that adenoviral vectors are able to transfer a reporter gene to the TM of postmortem human donors. However, assessing gene therapy for glaucoma requires models that can monitor changes in aqueous humor outflow facility (C = flow/pressure). In this study we used four replication-deficient adenoviruses in two such perfusion models. In the first model, whole porcine eyes were infected, perfused at constant pressure and flow changes recorded for 5 h. In the second one, anterior segments from human eyes were infected, perfused at constant flow and pressure changes recorded for 3 days. A single dose of 10(8) adenovirus plaque forming units (pfu) causes a reduction in C while single doses of 10(7), 10(6) and 10(5) p.f.u. do not affect outflow facility and retain positive gene transfer. These findings indicate that adenovirus, at effective doses, could become useful vectors for gene therapy of glaucoma.
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Affiliation(s)
- T Borrás
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27710, USA
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Abstract
The trabecular meshwork forms most of the resistance to aqueous humor outflow needed for maintenance of a pressure gradient between intraocular pressure of approximately 17 mmHg and venous pressure of approximately 10 mmHg. The composition of the extracellular material in the subendothelial or cribriform layer seems to be mainly responsible for outflow resistance. The aqueous humor pathways through the subendothelial layer can be influenced by ciliary muscle contraction and presumably also by contractile elements recently found both in trabecular meshwork and scleral spur. Pharmacologically induced disconnection of inner wall and cribriform cells leads to wash out of extracellular material through breaks of the endothelial lining of Schlemm's canal and to increase of outflow facility. In glaucomatous eyes the resistance to aqueous humor outflow is increased due to an increase in different forms of extracellular material deposited within the cribriform layer. The amount of this newly developed extracellular material is correlated with loss of axons in the optic nerve, indicating that a common factor is responsible for both changes. To investigate the effect of various factors on the biology of trabecular cells monolayer cultures derived from cribriform and corneoscleral trabecular meshwork have been established. The two cell lines can be differentiated because cribriform cells in vivo as in vitro stain for alphabeta-crystallin whereas the corneoscleral cells remain unstained. The effect of TGFbeta, a growth factor increased in aqueous humor of glaucomatous eyes and glycocorticoids on trabecular meshwork cells show typical changes in formation of extracellular matrix components and of stress proteins. Dexamethasone and oxidative damage also lead to increase of trabecular meshwork inducible glucocorticoid response (TIGR) protein. A mutation of the TIGR-gene family has recently been found in families with juvenile and chronic simple glaucoma. Future research has to clarify the significance of these genetic factors for the pathophysiology of glaucoma and the role of trabecular cell activity in this respect.
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Affiliation(s)
- E Lütjen-Drecoll
- Department of Anatomy II, University of Erlangen-Nürnberg, Erlangen, Germany
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40
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Johnson DH, Tschumper RC. Ethacrynic acid: outflow effects and toxicity in human trabecular meshwork in perfusion organ culture. Curr Eye Res 1993; 12:385-96. [PMID: 8344063 DOI: 10.3109/02713689309024620] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The effect of ethacrynic acid, a potential outflow agent for the treatment of glaucoma, was studied in a series of 25 pairs of human eyes in perfusion organ culture. Concentrations varied from 0.01 mM to 2.4 mM and were used in single or repetitive doses. Intraocular pressure was continuously recorded for up to two weeks after exposure. Eyes were then fixed and the meshwork examined histologically. Ethacrynic acid in single doses of 0.05 mM, 0.3 mM, and 0.6 mM increased facility of outflow at least 40% when compared with fellow control eyes. The duration of effect was approximately 18 hours, during which time the intraocular pressure gradually returned to baseline. Histologic examination revealed dose related effects on the trabecular cells, ranging from clumping of nuclear chromatin in some eyes to cellular swelling, disruption of cytoplasmic membranes, and cell necrosis in other eyes at concentrations of 0.1 mM and higher. No recovery or reversal of these changes was noted with time, even two weeks after a single exposure to the drug. Although ethacrynic acid is effective in temporarily lowering intraocular pressure in the human eye, a low therapeutic index may limit its clinical usefulness.
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Affiliation(s)
- D H Johnson
- Department of Ophthalmology, Mayo Clinic, Rochester, MN 55905
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41
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Tschumper RC, Johnson DH, Bradley JM, Acott TS. Glycosaminoglycans of human trabecular meshwork in perfusion organ culture. Curr Eye Res 1990; 9:363-9. [PMID: 2111236 DOI: 10.3109/02713689008999624] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The synthetic profile of glycosaminoglycans (GAGs) of human trabecular meshwork in perfusion organ culture was studied in a series of 34 human eyes. The anterior segments of these eyes were cultured for periods of two to 28 days and received medium containing 3H-glucosamine and 35S-sulfate during the final 48 hours of culture. The meshwork was then dissected and the GAGs isolated and subjected to sequential enzyme digestion. Active labelling of hyaluronic acid, chondroitin sulfate, dermatan sulfate, keratan sulfate, and heparan sulfate was found in all time periods. Eyes cultured seven and 14 days had similar incorporation profiles to "fresh" eyes (cultured 48 hours to allow for labelling). Eyes cultured 21 days showed an increase in dermatan sulfate labelling and a slight decrease in keratan sulfate labelling when compared with "fresh" eyes. Light microscopic autoradiography confirmed the trabecular meshwork incorporation of the radiolabelled precursors at all time periods. Thus, the trabecular meshwork remains metabolically active and GAG synthetic profiles remain reasonably similar to fresh eyes for up to three weeks in a perfusion organ culture system. This system may serve as a model for future studies of human trabecular meshwork GAGs.
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Affiliation(s)
- R C Tschumper
- Department of Ophthalmology, Mayo Foundation, Rochester, MN
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