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Efficacy and Safety of Glycosidic Enzymes for Improved Gene Delivery to the Retina following Intravitreal Injection in Mice.

ABSTRACT: Viral gene delivery is showing great promise for treating retinal disease. Although subretinal vector delivery has mainly been used to date, intravitreal delivery has potential advantages if low retinal transduction efficiency can be overcome. To this end, we investigated the effects of co-injection of glycosaminoglycan-degrading enzymes, singly or in combination, with AAV2 as a method of increasing retinal transduction. Experiments using healthy mice demonstrated that these enzymes enhance retinal transduction. We found that heparinase III produced the greatest individual effect, and this was enhanced further by combination with hyaluronan lyase. In addition, this optimized AAV2-enzyme combination led to a marked improvement in transduction in retinas with advanced retinal degeneration compared with AAV2 alone. Safety studies measuring retinal function by flash electroretinography indicated that retinal function was unaffected in the acute period and at least 12 months after enzyme treatment, whereas pupillometry confirmed that retinal ganglion cell activity was unaffected. Retinal morphology was not altered by the enzyme injection. Collectively these data confirm the efficacy and safety of this intravitreal approach in enhancing retinal transduction efficiency by AAV in rodents. Translating this method into other species, such as non-human primates, or for clinical applications will have challenges and require further studies.

SUBMITTER: Cehajic-Kapetanovic J

PROVIDER: S-EPMC5948313 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature

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Efficacy and Safety of Glycosidic Enzymes for Improved Gene Delivery to the Retina following Intravitreal Injection in Mice.

Cehajic-Kapetanovic Jasmina J Milosavljevic Nina N Bedford Robert A RA Lucas Robert J RJ Bishop Paul N PN

Molecular therapy. Methods & clinical development 20171222

Viral gene delivery is showing great promise for treating retinal disease. Although subretinal vector delivery has mainly been used to date, intravitreal delivery has potential advantages if low retinal transduction efficiency can be overcome. To this end, we investigated the effects of co-injection of glycosaminoglycan-degrading enzymes, singly or in combination, with AAV2 as a method of increasing retinal transduction. Experiments using healthy mice demonstrated that these enzymes enhance reti ...[more]

PMID: 29766027

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Project description:The glial protein S100B, which belongs to a calcium binding protein family, is up-regulated in neurological diseases, like multiple sclerosis or glaucoma. In previous studies, S100B immunization led to retinal ganglion cell (RGC) loss in an experimental autoimmune glaucoma (EAG) model. Now, the direct degenerative impact of S100B on the retina and optic nerve was evaluated. Therefore, 2 ?l of S100B was intravitreally injected in two concentrations (0.2 and 0.5 ?g/?l). At day 3, 14 and 21, retinal neurons, such as RGCs, amacrine and bipolar cells, as well as apoptotic mechanisms were analyzed. Furthermore, neurofilaments, myelin fibers and axons of optic nerves were evaluated. In addition, retinal function and immunoglobulin G (IgG) level in the serum were measured. At day 3, RGCs were unaffected in the S100B groups, when compared to the PBS group. Later, at days 14 and 21, the RGC number as well as the ?-III tubulin protein level was reduced in the S100B groups. Only at day 14, active apoptotic mechanisms were noted. The number of amacrine cells was first affected at day 21, while the bipolar cell amount remained comparable to the PBS group. Also, the optic nerve neurofilament structure was damaged from day 3 on. At day 14, numerous swollen axons were observed. The intraocular injection of S100B is a new model for a glaucoma like degeneration. Although the application site was the eye, the optic nerve degenerated first, already at day 3. From day 14 on, retinal damage and loss of function was noted. The RGCs in the middle part of the retina were first affected. At day 21, the damage expanded and RGCs had degenerated in all areas of the retina as well as amacrine cells. Furthermore, elevated IgG levels in the serum were measured at day 21, which could be a sign of a late and S100B independet immune response. In summary, S100B had a direct destroying impact on the axons of the optic nerve. The damage of the retinal cell bodies seems to be a consequence of this axon loss.

Project description:IntroductionNeovascular glaucoma is characterized by neovascularization of the iris and anterior angle chamber. Intravitreal anti-vascular endothelial growth factor agents may decrease intraocular pressure (IOP) and improve neovascularization. The VENERA study assessed the efficacy and safety of intravitreal aflibercept (IVT-AFL) in patients with neovascular glaucoma.MethodsThis was a 5-week, single-arm, nonrandomized, open-label, phase 3 study performed at 7 study sites in Japan that enrolled Japanese patients with anterior segment neovascularization and IOP > 25 mmHg who had not undergone (within 30 days prior), nor were imminently scheduled to undergo (within 8 days following) intraocular surgeries, including panretinal photocoagulation (PRP). Patients received background therapy plus 2 mg IVT-AFL at baseline. Background therapy with systemic IOP-lowering drugs was prohibited for 3 days before day 1 and until IOP evaluation at week 1. The primary endpoint was the change in IOP from baseline to week 1 and the secondary endpoint was the proportion of patients with an improvement of ≥ 1 grade of neovascularization of the angle (NVA) from baseline to week 1.ResultsSixteen patients received treatment (full analysis set); the per-protocol set comprised 15 patients. The mean IOP decreased from 34.1 mmHg at baseline to 25.8 mmHg at week 1 (mean change, -8.3 mmHg [95% confidence interval; CI -12.2 to -4.4; P = 0.0004]). At week 1, 81.3% of patients had an improvement in the grade of neovascularization of the iris (NVI) and 50.0% of patients had an improvement in NVA grade. The proportion of patients with controlled IOP (≤ 21 mmHg) was 43.8% (95% CI 19.8-70.1) at week 1, and increased to 56.3% at week 2 and 86.7% at week 5. The most common ocular treatment-emergent adverse event was eye pain, which occurred in 4 patients (25.0%).ConclusionsIVT-AFL was associated with statistically significant and clinically meaningful IOP reductions, without concomitant use of systemic IOP-lowering drugs or PRP. The safety profile was consistent with the known safety profile of IVT-AFL. These findings supplement those from the previous VEGA study, and suggest that IVT-AFL may be a potential treatment option for patients with neovascular glaucoma.Trial registrationClinicaltrials.gov identifier NCT03639675.

Dataset Information

Efficacy and Safety of Glycosidic Enzymes for Improved Gene Delivery to the Retina following Intravitreal Injection in Mice.

Publications

Efficacy and Safety of Glycosidic Enzymes for Improved Gene Delivery to the Retina following Intravitreal Injection in Mice.

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