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Schwakopf J, Romero CO, Lopez NN, Millar JC, Vetter ML, Bosco A. Schlemm's canal-selective Tie2/TEK knockdown induces sustained ocular hypertension in adult mice. Exp Eye Res 2024; 248:110114. [PMID: 39368692 PMCID: PMC11533709 DOI: 10.1016/j.exer.2024.110114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2024] [Revised: 09/19/2024] [Accepted: 10/01/2024] [Indexed: 10/07/2024]
Abstract
Deficient Angiopoietin-Tie2 signaling is linked to ocular hypertension in glaucoma. Receptor Tie2/TEK expression and signaling at Schlemm's canal (SC) is indispensable for canal integrity and homeostatic regulation of aqueous humor outflow (AHO) and intraocular pressure (IOP), as validated by conditional deletion of Tie2, its ligands (Angpt1, Angpt2 and Angpt3/4) or regulators (Tie1 and PTPRB/VE-PTP). However, these Tie2/TEK knockouts and conditional knockouts are global or endothelial, preventing separation of systemic and ocular vascular defects that impact retinal or renal integrity. To develop a more targeted model of ocular hypertension induced by selective knockdown of Tie2/TEK expressed in SC, we combined the use of viral vectors to target the canal, and two distinct gene-editing strategies to disrupt the Tie2 gene. Adeno-associated virus (AAV2) is known to transduce rodent SC when delivered into the anterior chamber by intracameral injection. First, delivery of Cre recombinase via AAV2.Cre into R26tdTomato/+ reporter mice confirmed preferential and stable transduction in SC endothelium. Next, to disrupt Tie2 expression in SC, we injected AAV2.Cre into homozygous floxed Tie2 (Tie2FL/FL) mice. This led to attenuated Tie2 protein expression along the SC inner wall, decreased SC area and reduced trabecular meshwork (TM) cellularity. Functionally, IOP was significantly and steadily elevated, whereas AHO facility was reduced. In contrast, hemizygous Tie2FL/+ mice responded to AAV2.Cre with inconsistent and low IOP elevation, corroborating the dose-dependency of ocular hypertension on Tie2 expression/activation. In a second model using CRISPR/SaCas9 genome editing, wild-type C57BL/6 J mice injected with AAV2.saCas9-sgTie2 showed similar selective SC transduction and comparable IOP elevation in course and magnitude to that induced by AAV2.Cre in Tie2FL/FL mice. Together, our findings, demonstrate that selective Tie2 knockdown in SC is a targeted strategy that reliably induces chronic ocular hypertension and reproduces glaucomatous damage to the conventional outflow pathway, providing novel models of SC-Tie2 signaling loss valuable for preclinical studies.
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Affiliation(s)
- Joon Schwakopf
- Department of Neurobiology, University of Utah, Salt Lake City, UT, 84132, USA
| | - Cesar O Romero
- Department of Neurobiology, University of Utah, Salt Lake City, UT, 84132, USA
| | - Navita N Lopez
- Department of Neurobiology, University of Utah, Salt Lake City, UT, 84132, USA
| | - J Cameron Millar
- Department of Pharmacology and Neuroscience and North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, 76107, USA
| | - Monica L Vetter
- Department of Neurobiology, University of Utah, Salt Lake City, UT, 84132, USA
| | - Alejandra Bosco
- Department of Neurobiology, University of Utah, Salt Lake City, UT, 84132, USA.
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Kim D, Fang R, Zhang P, Sun C, Li G, Montgomery C, John SWM, Stamer WD, Zhang HF, Ethier CR. In vivo quantification of anterior and posterior chamber volumes in mice: implications for aqueous humor dynamics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.24.604989. [PMID: 39091756 PMCID: PMC11291131 DOI: 10.1101/2024.07.24.604989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
Purpose Aqueous humor inflow rate, a key parameter influencing aqueous humor dynamics, is typically measured by fluorophotometery. Analyzing fluorophotometric data depends, inter alia, on the volume of aqueous humor in the anterior, but not the posterior, chamber. Previous fluorophotometric studies of aqueous inflow rate in mice have assumed the ratio of anterior:posterior volumes in mice to be similar to those in humans. Our goal was to measure anterior and posterior chamber volumes in mice to facilitate better estimates of aqueous inflow rates. Methods We used standard near-infrared optical coherence tomography (OCT) and robotic visible-light OCT (vis-OCT) to visualize, reconstruct and quantify the volumes of the anterior and posterior chambers of the mouse eye in vivo. We used histology and micro-CT scans to validate relevant landmarks from ex vivo tissues to facilitate in vivo measurement. Results Posterior chamber volume is 1.1 times the anterior chamber volume in BALB/cAnNCrl mice, i.e. the anterior chamber constitutes about 47% of the total aqueous humor volume, which is very dissimilar to the situation in humans. Anterior chamber volumes in 2-month-old BALB/cAnNCrl and 7-month-old C57BL6/J mice were 1.55 ± 0.36 μL (n=10) and 2.41 ± 0.29 μL (n=8), respectively. This implies that previous studies likely over-estimated aqueous inflow rate by approximately two-fold. Conclusions It is necessary to reassess previously reported estimates of aqueous inflow rates, and thus aqueous humor dynamics in the mouse. For example, we now estimate that only 0-15% of aqueous humor drains via the pressure-independent (unconventional) route, similar to that seen in humans and monkeys.
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Affiliation(s)
- Daniel Kim
- Department of Biomedical Engineering, Northwestern University, Evanston, IL
| | - Raymond Fang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL
| | - Pengpeng Zhang
- Department of Mechanical Engineering, Northwestern University, Evanston, IL
| | - Cheng Sun
- Department of Mechanical Engineering, Northwestern University, Evanston, IL
| | - Guorong Li
- Department of Ophthalmology, Duke University, Durham, NC
| | - Christa Montgomery
- Department of Ophthalmology, Columbia University Irving Medical Center, and Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY
| | - Simon W M John
- Department of Ophthalmology, Columbia University Irving Medical Center, and Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY
| | | | - Hao F Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL
| | - C Ross Ethier
- Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA
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Xia X, Guo X. Adeno-associated virus vectors for retinal gene therapy in basic research and clinical studies. Front Med (Lausanne) 2023; 10:1310050. [PMID: 38105897 PMCID: PMC10722277 DOI: 10.3389/fmed.2023.1310050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 11/09/2023] [Indexed: 12/19/2023] Open
Abstract
Retinal degenerative diseases, including glaucoma, age-related macular degeneration, diabetic retinopathy, and a broad range of inherited retinal diseases, are leading causes of irreversible vision loss and blindness. Gene therapy is a promising and fast-growing strategy to treat both monogenic and multifactorial retinal disorders. Vectors for gene delivery are crucial for efficient and specific transfer of therapeutic gene(s) into target cells. AAV vectors are ideal for retinal gene therapy due to their inherent advantages in safety, gene expression stability, and amenability for directional engineering. The eye is a highly compartmentalized organ composed of multiple disease-related cell types. To determine a suitable AAV vector for a specific cell type, the route of administration and choice of AAV variant must be considered together. Here, we provide a brief overview of AAV vectors for gene transfer into important ocular cell types, including retinal pigment epithelium cells, photoreceptors, retinal ganglion cells, Müller glial cells, ciliary epithelial cells, trabecular meshwork cells, vascular endothelial cells, and pericytes, via distinct injection methods. By listing suitable AAV vectors in basic research and (pre)clinical studies, we aim to highlight the progress and unmet needs of AAV vectors in retinal gene therapy.
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Affiliation(s)
| | - Xinzheng Guo
- State Key Laboratory of Common Mechanism Research for Major Diseases, Suzhou Institute of Systems Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Suzhou, China
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Tan JK, Xiao Y, Liu G, Huang LX, Ma WH, Xia Y, Wang XZ, Zhu XJ, Cai SP, Wu XB, Wang Y, Liu XY. Evaluation of trabecular meshwork-specific promoters in vitro and in vivo using scAAV2 vectors expressing C3 transferase. Int J Ophthalmol 2023; 16:1196-1209. [PMID: 37602341 PMCID: PMC10398517 DOI: 10.18240/ijo.2023.08.03] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 03/14/2023] [Indexed: 08/22/2023] Open
Abstract
AIM To evaluate the potential of two trabecular meshwork (TM)-specific promoters, Chitinase 3-like 1 (Ch3L1) and matrix gla protein (MGP), for improving specificity and safety in glaucoma gene therapy based on self-complementary AAV2 (scAAV2) vector technologies. METHODS An scAAV2 vector with C3 transferase (C3) as the reporter gene (scAAV2-C3) was selected. The scAAV2-C3 vectors were driven by Ch3L1 (scAAV2-Ch3L1-C3), MGP (scAAV2-MGP-C3), enhanced MGP (scAAV2-eMGP-C3) and cytomegalovirus (scAAV2-CMV-C3), respectively. The cultured primary human TM cells were treated with each vector at different multiplicities of infections. Changes in cell morphology were observed by phase contrast microscopy. Actin stress fibers and Rho GTPases/Rho-associated protein kinase pathway-related molecules were assessed by immunofluorescence staining, real-time quantitative polymerase chain reaction and Western blot. Each vector was injected intracamerally into the one eye of each rat at low and high doses respectively. In vivo green fluorescence was visualized by a Micron III Retinal Imaging Microscope. Intraocular pressure (IOP) was monitored using a rebound tonometer. Ocular responses were evaluated by slit-lamp microscopy. Ocular histopathology analysis was examined by hematoxylin and eosin staining. RESULTS In TM cell culture studies, the vector-mediated C3 expression induced morphologic changes, disruption of actin cytoskeleton and reduction of fibronectin expression in TM cells by inhibiting the Rho GTPases/Rho-associated protein kinase signaling pathway. At the same dose, these changes were significant in TM cells treated with scAAV2-CMV-C3 or scAAV2-Ch3L1-C3, but not in cells treated with scAAV2-eMGP-C3 or scAAV2-MGP-C3. At low-injected dose, the IOP was significantly decreased in the scAAV2-Ch3L1-C3-injected eyes but not in scAAV2-MGP-C3-injected and scAAV2-eMGP-C3-injected eyes. At high-injected dose, significant IOP reduction was observed in the scAAV2-eMGP-C3-injected eyes but not in scAAV2-MGP-C3-injected eyes. Similar to scAAV2-CMV-C3, scAAV2-Ch3L1-C3 vector showed efficient transduction both in the TM and corneal endothelium. In anterior segment tissues of scAAV2-eMGP-C3-injected eyes, no obvious morphological changes were found except for the TM. Inflammation was absent. CONCLUSION In scAAV2-transduced TM cells, the promoter-driven efficiency of Ch3L1 is close to that of cytomegalovirus, but obviously higher than that of MGP. In the anterior chamber of rat eye, the transgene expression pattern of scAAV2 vector is presumably affected by MGP promoter, but not by Ch3L1 promoter. These findings would provide a useful reference for improvement of specificity and safety in glaucoma gene therapy using scAAV2 vector.
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Affiliation(s)
- Jun-Kai Tan
- Xiamen Eye Center, Xiamen University, Xiamen 361004, Fujian Province, China
| | - Ying Xiao
- Department of Pathology, Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu 610032, Sichuan Province, China
| | - Guo Liu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu 610072, Sichuan Province, China
| | - Long-Xiang Huang
- The First Affiliated Hospital of Fujian Medical University, Fuzhou 350004, Fujian Province, China
| | - Wen-Hao Ma
- Beijing FivePlus Molecular Medicine Institute Co., Ltd., Beijing 102600, China
| | - Yan Xia
- Beijing FivePlus Molecular Medicine Institute Co., Ltd., Beijing 102600, China
| | - Xi-Zhen Wang
- Shenzhen Key Laboratory of Ophthalmology, Shenzhen Eye Hospital, School of Optometry, Jinan University, Shenzhen 518040, Guangdong Province, China
| | - Xian-Jun Zhu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu 610072, Sichuan Province, China
| | - Su-Ping Cai
- Shenzhen Key Laboratory of Ophthalmology, Shenzhen Eye Hospital, School of Optometry, Jinan University, Shenzhen 518040, Guangdong Province, China
| | - Xiao-Bing Wu
- Beijing FivePlus Molecular Medicine Institute Co., Ltd., Beijing 102600, China
| | - Yun Wang
- Shenzhen Key Laboratory of Ophthalmology, Shenzhen Eye Hospital, School of Optometry, Jinan University, Shenzhen 518040, Guangdong Province, China
| | - Xu-Yang Liu
- Xiamen Eye Center, Xiamen University, Xiamen 361004, Fujian Province, China
- Department of Ophthalmology, Shenzhen People's Hospital, the 2 Clinical Medical College, Jinan University, Shenzhen 518020, Guangdong Province, China
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