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Evaluation of the Effectiveness of a Chronic Ocular Hypertension Mouse Model Induced by Intracameral Injection of Cross-Linking Hydrogel.

ABSTRACT: Background: Glaucoma is an irreversible and blinding neurodegenerative disease that is characterized by progressive loss of retinal ganglion cells. The current animal models of glaucoma fail to provide a chronic elevated intraocular pressure and cannot maintain the optical media clarity for a long time, which brings some difficulties to the study of glaucoma. Here, we developed a new chronic ocular hypertension model of mice induced by cross-linking hydrogel intracameral injection. Methods: C57BL/6J mice aged 6-8 weeks were randomly divided into the control group and the operation group. The mice of the operation group were injected with cross-linking hydrogel to induce ocular hypertension. Intraocular pressure was measured preoperatively, 3 days after surgery, and weekly until the end of the study. Flash visual evoked potential (F-VEP) was used to observe optic nerve function at different times (preoperatively and 2, 4, and 6 weeks) after chronic ocular hypertension (COH). Retinal TNF-α, IL-1β, and IL-17A protein expression were measured by western blotting in the control group and in mice at 2, 4, and 6 weeks after COH. Microglial cell activation was evaluated by immunofluorescence staining and western blotting. Apoptosis and loss of retinal ganglion cells after 2, 4, and 6 weeks of intracameral injection of cross-linking hydrogel were observed by the TUNEL assay and Brn3a protein labeling. The loss of optic nerve axons in COH mice was evaluated by neurofilament heavy polypeptide protein labeling. Results: Intracameral injection of the cross-linking hydrogel induces increased intraocular pressure (IOP) to a mean value of 19.3 ± 4.1 mmHg, which was sustained for at least 8 weeks. A significant difference in IOP was noted between COH mice and sham-operation mice (p < 0.0001). The success rate was 75%. The average amplitude of F-VEP in mice with COH was reduced (p = 0.0149, 0.0012, and 0.0009 at 2, 4, and 6 weeks after COH vs. the control group, respectively), and the average latent period in mice with COH was longer (p = 0.0290, <0.0001, and <0.0001 at 2, 4, and 6 weeks after COH vs. the control group, respectively) compared with that in the control group. TNF-α, IL-1β, IL-17A, Iba-1, and CD68 protein expression increased in COH mice. During the processing of COH, the number of microglial cells increased along with cellular morphological changes of rounder bodies and thicker processes compared with the control group. Apoptosis of retinal ganglion cells (RGCs) was clearly observed in mice at 2, 4, and 6 weeks after COH (p = 0.0061, 0.0012, <0.0001, and 0.0371 at 2, 4, and 6 weeks after COH vs. the control group, respectively). The RGC density decreased significantly in the COH mice compared with the control group (p = 0.0042, 0.0036, and <0.0001 at 2, 4, and 6 weeks after COH vs. the control group, respectively). There was a significant loss of optic nerve axons in mice after intracameral injection of cross-linking hydrogel (p = 0.0095, 0.0002, and <0.0001 at 2, 4, and 6 weeks after COH vs. the control group, respectively). Conclusions: A single intracameral injection of cross-linking hydrogel can effectively induce chronic ocular hypertension in mice, which causes progressive loss of retinal ganglion cells, increased expression levels of inflammatory cytokines and microglial cell activation, and deterioration of optic nerve function.

SUBMITTER: Chen J

PROVIDER: S-EPMC8019751 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Investigation of neurodegeneration in glaucoma, a leading cause of irreversible blindness worldwide, has been obfuscated by the lack of an efficient model that provides chronic, mild to moderate elevation of intraocular pressure (IOP) with preservation of optical media clarity for long term, in vivo interrogation of the structural and functional integrity of the retinal ganglion cells (RGCs). Here, we designed and formulated an injectable hydrogel based on in situ cross-linking of hyaluronic acid functionalized with vinyl sulfone (HA-VS) and thiol groups (HA-SH). Intracameral injection of HA-VS and HA-SH in C57BL/6J mice exhibited mild to moderate elevation of IOP with daily mean IOP ranged between 14?±?3 and 24?±?3?mmHg, which led to progressive, regional loss of RGCs evaluated with in vivo, time-lapse confocal scanning laser ophthalmoscopy; a reduction in fractional anisotropy in the optic nerve and the optic tract projected from the eye with increased IOP in diffusion tensor magnetic resonance imaging; a decrease in positive scotopic threshold response in electroretinography; and a decline in visual acuity measured with an optokinetic virtual reality system. The proportion of RGC loss was positively associated with the age of the animals, and the levels and the duration of IOP elevation. The new glaucoma model recapitulates key characteristics of human glaucoma which is pertinent to the development and pre-clinical testing of neuroprotective and neuroregenerative therapies. STATEMENT OF SIGNIFICANCE: A new model to study chronic neurodegeneration in glaucoma has been developed via intracameral injection of a specifically designed hyaluronic acid functionalized with vinyl sulfone and thiol groups for cross-linking. Intracameral injection of the chemically cross-linked hydrogel generates mild to moderate IOP elevation, resulting in progressive degeneration of the retinal ganglion cells, optic nerve, and optic tract, and a decline in visual function. The model recapitulates the key features of neurodegeneration in human glaucoma, which will facilitate and expedite the development of neuroprotective and neuroregenerative therapies.

Project description:IntroductionThis study evaluated the intraocular pressure (IOP)-lowering efficacy and safety of a single intracameral administration of bimatoprost implant 10 µg in adults with open-angle glaucoma or ocular hypertension.MethodsTwo identically designed, randomized, 20-month, parallel-group, phase 3 clinical trials (one study eye/patient) compared three administrations of 10- or 15-µg bimatoprost implant (day 1, weeks 16 and 32) with twice-daily topical timolol maleate 0.5%. An open-label, 24-month, phase 1/2 clinical trial compared one or two implants administered in the study eye with once-daily topical bimatoprost 0.03% in the fellow eye. Separate analyses of the pooled phase 3 and phase 1/2 study datasets evaluated outcomes in the 10-µg bimatoprost implant and comparator treatment arms after a single implant administration, up to the time of implant re-administration or rescue with IOP-lowering medication.ResultsIn the phase 3 studies, 10-µg bimatoprost implant single administration demonstrated IOP reductions (hour 0) of 4.9-7.0 mmHg through week 15 from a mean (standard deviation, SD) baseline IOP of 24.5 (2.6) mmHg (n = 374); IOP in the topical timolol BID group was reduced by 6.0-6.3 mmHg from a mean (SD) baseline IOP of 24.5 (2.6) mmHg (n = 373). In the phase 1/2 study (n = 21), median time to use of additional IOP-lowering treatment (Kaplan-Meier analysis) was 273 days (approximately 9 months), and 5 of 21 enrolled patients (23.8%) required no additional IOP-lowering treatment up to 24 months after single administration. In each study, after a single implant administration there were no reports of corneal edema, corneal endothelial cell loss, or corneal touch, and no patients had 20% or greater loss in corneal endothelial cell density.ConclusionsBimatoprost implant single administration lowers IOP and has a favorable safety profile. Additional studies are needed to further evaluate the duration of effect and factors predicting long-term IOP lowering after a single implant administration.Trial registration numbersClinicalTrials.gov NCT02247804, NCT02250651, and NCT01157364.

Project description:IntroductionThis prospective, multicenter, randomized, double-masked pivotal phase 3 trial evaluated the efficacy and safety of the travoprost intracameral SE-implant (slow-eluting implant, the intended commercial product) and FE-implant (fast-eluting implant, included primarily for masking purposes) compared to twice-daily (BID) timolol ophthalmic solution, 0.5% in patients with open-angle glaucoma (OAG) or ocular hypertension (OHT).MethodsThe trial enrolled adult patients with OAG or OHT with an unmedicated mean diurnal intraocular pressure (IOP) of ≥ 21 and unmedicated IOP ≤ 36 mmHg at each diurnal timepoint (8 A.M., 10 A.M., and 4 P.M.) at baseline. The eligible eye of each patient was administered an SE-implant, an FE-implant or had a sham administration procedure. Patients who received an implant were provided placebo eye drops to be administered BID and patients who had the sham procedure were provided timolol eye drops to be administered BID. The primary efficacy endpoint, for which the study was powered, was mean change from baseline IOP at 8 A.M. and 10 A.M. at day 10, week 6, and month 3. Non-inferiority was achieved if the upper 95% confidence interval (CI) on the difference in IOP change from baseline (implant minus timolol) was < 1.5 mmHg at all six timepoints and < 1 mmHg at three or more timepoints. The key secondary endpoint was mean change from baseline IOP at 8 A.M. and 10 A.M. at month 12. Non-inferiority at month 12 was achieved if the upper 95% CI was < 1.5 mmHg at both timepoints. Safety outcomes included treatment-emergent adverse events (TEAEs) and ophthalmic assessments.ResultsA total of 590 patients were enrolled at 45 sites and randomized to one of three treatment groups: 197 SE-implant (the intended commercial product), 200 FE-implant, and 193 timolol. The SE-implant was non-inferior to timolol eye drops in IOP lowering over the first 3 months, and was also non-inferior to timolol at months 6, 9, and 12. The FE-implant was non-inferior to timolol over the first 3 months, and also at months 6 and 9. Of those patients who were on glaucoma medication at screening, a significantly greater proportion of patients in the SE- and FE-implant groups (83.5% and 78.7%, respectively) compared to the timolol group (23.9%) were on fewer topical glaucoma medications at month 12 compared to screening (P < 0.0001, chi-square test). TEAEs, mostly mild, were reported in the study eyes of 39.5% of patients in the SE-implant group, 34.0% of patients in the FE-implant group and 20.1% of patients in the timolol group.ConclusionsThe SE-travoprost intracameral implant demonstrated non-inferiority to timolol over 12 months whereas the FE-implant demonstrated non-inferiority over 9 months. Both implant models were safe and effective in IOP lowering in patients with OAG or OHT.Trial registrationClinicalTrials.gov identifier, NCT03519386.

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Evaluation of the Effectiveness of a Chronic Ocular Hypertension Mouse Model Induced by Intracameral Injection of Cross-Linking Hydrogel.

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