Ophthalmology (Eye & Ear Hospital) - Research Publications
Permanent URI for this collection
Search Results
1 - 4 of 4
-
ItemTargeted delivery of LM22A-4 by cubosomes protects retinal ganglion cells in an experimental glaucoma model(ELSEVIER SCI LTD, 2021-05)Glaucoma, a major cause of irreversible blindness worldwide, is associated with elevated intraocular pressure (IOP) and progressive loss of retinal ganglion cells (RGCs) that undergo apoptosis. A mechanism for RGCs injury involves impairment of neurotrophic support and exogenous supply of neurotrophic factors has been shown to be beneficial. However, neurotrophic factors can have widespread effects on neuronal tissues, thus targeting neurotrophic support to injured neurons may be a better neuroprotective strategy. In this study, we have encapsulated LM22A-4, a small neurotrophic factor mimetic, into Annexin V-conjugated cubosomes (L4-ACs) for targeted delivery to injured RGCs in a model of acute IOP elevation, which is induced by acute IOP elevation. We have tested cubosomes formulations that encapsulate from 9% to 33% LM22A-4. Our data indicated that cubosomes encapsulating 9% and 17% LM22A-4 exhibited a mixture of Pn3m/Im3m cubic phase, whereas 23% and 33% showed a pure Im3m cubic phase. We found that 17% L4-ACs with Pn3m/Im3m symmetries showed better in-situ and in-vitro lipid membrane interactions than the 23% and 33% L4-ACs with Im3m symmetry. In vivo experiments showed that 17% L4-ACs targeted the posterior retina and the optic nerve head, which prevented RGCs loss and improved functional outcomes in a mouse model of acute IOP elevation. These results provide evidence that Annexin V-conjugated cubosomes-based LM22A-4 delivery may be a useful targeted approach to prevent the progression of RGCs loss in glaucoma. STATEMENT OF SIGNIFICANCE: Recent studies suggest that the therapy of effectively delivering neurotrophic factors to the injured retinal ganglion cells (RGCs) could promote the survival of RGCs in glaucoma. Our present work has for the first time used cubosomes as an active targeted delivery system and have successfully delivered a neuroprotective drug to the damaged RGCs in vivo. Our new cubosomal formulation can protect apoptotic cell death in vitro and in vivo, showing that cubosomes are a promising drug carrier system for ocular drug delivery and glaucoma treatment. We have further found that by controlling cubosomes in Pn3m phase we can facilitate delivery of neuroprotective drug through apoptotic membranes. This data, we believe, has important implications for future design and formulation of cubosomes for therapeutic applications.
-
ItemGene Therapy Intervention in Neovascular Eye Disease: A Recent Update(CELL PRESS, 2020-10-07)Aberrant growth of blood vessels (neovascularization) is a key feature of severe eye diseases that can cause legal blindness, including neovascular age-related macular degeneration (nAMD) and diabetic retinopathy (DR). The development of anti-vascular endothelial growth factor (VEGF) agents has revolutionized the treatment of ocular neovascularization. Novel proangiogenic targets, such as angiopoietin and platelet-derived growth factor (PDGF), are under development for patients who respond poorly to anti-VEGF therapy and to reduce adverse effects from long-term VEGF inhibition. A rapidly advancing area is gene therapy, which may provide significant therapeutic benefits. Viral vector-mediated transgene delivery provides the potential for continuous production of antiangiogenic proteins, which would avoid the need for repeated anti-VEGF injections. Gene silencing with RNA interference to target ocular angiogenesis has been investigated in clinical trials. Proof-of-concept gene therapy studies using gene-editing tools such as CRISPR-Cas have already been shown to be effective in suppressing neovascularization in animal models, highlighting the therapeutic potential of the system for treatment of aberrant ocular angiogenesis. This review provides updates on the development of anti-VEGF agents and novel antiangiogenic targets. We also summarize current gene therapy strategies already in clinical trials and those with the latest approaches utilizing CRISPR-Cas gene editing against aberrant ocular neovascularization.
-
ItemA drug-tunable Flt23k gene therapy for controlled intervention in retinal neovascularization(SPRINGER, 2021-02)Gene therapies that chronically suppress vascular endothelial growth factor (VEGF) represent a new approach for managing retinal vascular leakage and neovascularization. However, constitutive suppression of VEGF in the eye may have deleterious side effects. Here, we developed a novel strategy to introduce Flt23k, a decoy receptor that binds intracellular VEGF, fused to the destabilizing domain (DD) of Escherichia coli dihydrofolate reductase (DHFR) into the retina. The expressed DHFR(DD)-Flt23k fusion protein is degraded unless "switched on" by administering a stabilizer; in this case, the antibiotic trimethoprim (TMP). Cells transfected with the DHFR(DD)-Flt23k construct expressed the fusion protein at levels correlated with the TMP dose. Stabilization of the DHFR(DD)-Flt23k fusion protein by TMP was able to inhibit intracellular VEGF in hypoxic cells. Intravitreal injection of self-complementary adeno-associated viral vector (scAAV)-DHFR(DD)-Flt23k and subsequent administration of TMP resulted in tunable suppression of ischemia-induced retinal neovascularization in a rat model of oxygen-induced retinopathy (OIR). Hence, our study suggests a promising novel approach for the treatment of retinal neovascularization. Schematic diagram of the tunable system utilizing the DHFR(DD)-Flt23k approach to reduce VEGF secretion. a The schematic shows normal VEGF secretion. b Without the ligand TMP, the DHFR(DD)-Flt23k protein is destabilized and degraded by the proteasome. c In the presence of the ligand TMP, DHFR(DD)-Flt23k is stabilized and sequestered in the ER, thereby conditionally inhibiting VEGF. Green lines indicate the intracellular and extracellular distributions of VEGF. Blue lines indicate proteasomal degradation of the DHFR(DD)-Flt23k protein. Orange lines indicate the uptake of cell-permeable TMP. TMP, trimethoprim; VEGF, vascular endothelial growth factor; ER, endoplasmic reticulum.
-
ItemTargeted delivery of LM22A-4 by cubosomes protects retinal ganglion cells in an experimental glaucoma model(SSRN, 2021-04-29)Glaucoma, a major cause of irreversible blindness worldwide, is associated with elevated intraocular pressure (IOP) and progressive loss of retinal ganglion cells (RGCs) that undergo apoptosis. A mechanism for RGCs injury involves impairment of neurotrophic support and exogenous supply of neurotrophic factors has been shown to be beneficial. However, neurotrophic factors can have widespread effects on neuronal tissues, thus targeting neurotrophic support to injured neurons may be a better neuroprotective strategy. In this study, we have encapsulated LM22A-4, a small neurotrophic factor mimetic, into Annexin V-conjugated cubosomes (L4-ACs) for targeted delivery to injured RGCs in a model of glaucoma, which is induced by acute IOP elevation. We have tested cubosomes formulations that encapsulate from 9% to 33% LM22A-4. Our data indicated that cubosomes encapsulating 9% and 17% LM22A-4 exhibited a mixture of Pn3m/Im3m cubic phase, whereas 23% and 33% showed a pure Im3m cubic phase. We found that 17% L4-ACs with Pn3m/Im3m symmetries showed better in-situ and in-vitro lipid membrane interactions than the 23% and 33% L4-ACs with Im3m symmetry. In vivo experiments showed that 17% L4-ACs targeted the posterior retina and the optic nerve head, which prevented RGCs loss in a mouse model of acute IOP elevation. These results provide evidence that cubosomesbased LM22A-4 delivery may be a useful targeted approached to prevent the progression of RGCs loss in glaucoma.