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Accumulation of lipofuscin in the retinal pigment epithelium (RPE) is a hallmark of aging and is associated with retinal degeneration encountered in age-related macular degeneration (AMD) and Stargardt disease (SD). Currently, treatment for lipofuscin-induced retinal degeneration is unavailable. Here, we report that Remofuscin (INN: soraprazan, a tetrahydropyridoether small molecule) reverses lipofuscin accumulation in aged primary human RPE cells and is non-cytotoxic in aged SD mouse RPE cells in vitro. In addition, we show that the removal of lipofuscin after a single intravitreal injection of Remofuscin results in a rescue from retinal degeneration in a mouse model of advanced SD which is even accompanied by an amelioration of the retinal dysfunction. Finally, we demonstrate that the mechanism causing lipofuscinolysis may involve the reactive oxygen species generated via the presence of Remofuscin. These data suggest a possible therapeutic approach to untreatable lipofuscin-mediated diseases like AMD, SD and lipofuscinopathies in neurodegenerative diseases., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: To study the suitability of injectable microspheres based on poly(ester amide) (PEA) or poly lactic-co-glycolic acid (PLGA) as potential vehicles for intravitreal drug delivery in rat eyes. Dexamethasone-loaded PEA microspheres (PEA + DEX) were also evaluated., Methods: Forty male Sprague Dawley rats were divided into four groups that received different intravitreally injected microspheres: PEA group (n = 12); PLGA group (n = 12); PEA + DEX group (n = 8); and control group (no injection, n = 8). Electroretinography (ERG), fundus autofluorescence (FAF), and spectral domain optical coherence tomography (sdOCT) were performed at baseline, weeks 1 and 2, and months 1, 2, and 3 after intravitreal injection. Eyes were histologically examined using light microscopy and transmission electron microscopy at the end of the in vivo study., Results: There were no statistically significant changes in ERG among the groups. Abnormal FAF pattern and abnormal deposits in OCT were observed after injection but almost completely disappeared between week 2 and month 3 in all injected groups. GFAP staining showed that Müller glia cell activation was most pronounced in PLGA-injected eyes. Increased cell death was not observed by TUNEL staining at month 1. In electron microscopy at month 3, the remnants of microparticles were found in the retinal cells of all injected groups, and loss of plasma membrane was seen in the PLGA group., Conclusions: Although morphological changes such as mild glial activation and material remnants were observed histologically 1 month and 3 months after injection in all injected groups, minor cell damage was noted only in the PLGA group at 3 months after injection. No evidence of functional abnormality relative to untreated eyes could be detected by ERG 3 months after injection in all groups. Changes observed in in vivo imaging such as OCT and FAF disappeared after 3 months in almost all cases., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Subretinal implants aim to replace the photoreceptor function in patients suffering from degenerative retinal disease by topically applying electrical stimuli in the subretinal space. Critical obstacles in the design of high-resolution subretinal implants include the proximity of stimulating electrodes to the target cells and enabling nutrient flow between the retina and the choroid. The present work evaluates the adhesion, migration and survival of retinal cells on an ultrathin (5 μm), highly porous (Ø 1 μm spaced 3 μm), gelatin-coated polyimide (PI) membrane. The biocompatibility was examined in mice indicating a good tolerance upon subcutaneous implantation with only a mild inflammatory response. In addition, organotypic cultures of rat retina evidenced that the porous membrane allowed the necessary nutrient flow for the retinal cell survival and maintenance. A transscleral implantation technique was applied to position the membrane into the subretinal space of rats. The effect on the obtained retinal integration was investigated in vivo using scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT). In 12 out of 18 rat eyes, the implant was successfully placed subretinally. SLO and OCT demonstrated complete retinal attachment and fluorescein angiography showed no retinal vascular abnormalities over and around the implant, immediately after and up to four weeks after the implantation. Histological examination of the eyes showed a close attachment of a thin fibrocyte layer to the implant, the occlusion of the pores by living cells and the survival of some photoreceptors at the implantation site., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Purpose: To examine the ultrastructural effect of intravitreal bevacizumab on primate eyes with particular focus set on the choriocapillaris and to examine the influence of vascular endothelial growth factor (VEGF) inhibition on endothelial cell fenestration., Design: Animal study., Methods: Four Cynomolgus monkeys received an intravitreal injection of 1.25 mg bevacizumab. The eyes were enucleated and prepared for light and electron microscopy on days one, four, seven, and 14. Control eyes remained untreated. Choriocapillaris endothelial cell fenestrations were quantified., Results: Choriocapillaris endothelial cell fenestrations were significantly reduced after intravitreal injection of bevacizumab. Fenestration was lowest on day four (15.9 +/- 6.7 per 25 microm) and increased again from days seven to 14, but was still significantly lower than in the control (66.2 +/- 9.5 per 25 microm). Densely packed thrombocytes and leukocytes regionally occluded the choriocapillaris lumen of treated eyes. On day one an increased number of leukocytes filled in the choriocapillaris lumen. Photoreceptors were damaged in two of 40 light microscopic sections. On days one to seven, choroidal melanocytes contained giant melanosomes. None of these described features was found in controls., Conclusions: Intravitreal bevacizumab causes ultrastructural changes in the choriocapillaris of primate eyes. A significant reduction of choriocapillaris endothelial cell fenestrations is seen as early as 24 hours after injection and their number increases again after two weeks. These findings may play a role in the early clinical effect of intravitreal bevacizumab for macular edema. Because an increased risk of circulation disturbances in the choriocapillaris cannot be excluded, patients should be carefully monitored.

Bovine serum albumin (BSA) was exposed to hydroxyl radicals generated by the Fenton reaction. The reaction of the BSA solution with hydroxyl radicals resulted in a colour change from clear transparent to dark brown. The reaction was followed spectrophometrically. It was observed that during the reaction of BSA with hydroxyl radicals, a melanin-like absorption spectrum developed. The reaction with ferricyanide and the dark brown BSA solution resulted in the same dark blue-green colour as is typical for melanin. The results suggest that, by the reaction of BSA with hydroxyl radicals, melanin was formed.

1. The ultrastructure of the retinal pigment epithelium (RPE) of adult Syrian golden hamsters and cattle was examined with respect to pigment granules and phagosomes involved in degradation of disk membranes from rod outer segments. 2. In the RPE of cattle, phagosomes were found that contained an electron-dense melanin-like material that was not autofluorescent and therefore not lipofuscin. 3. Disk membranes of rods are about 4 nm thick and become enlarged (7-20 nm) and electron-dense during degradation in the RPE. 4. Additionally electron-dense vesiculo-globular bodies (10-100 nm) were found in phagosomes during disk membrane degradation and in mature melanin granules. 5. In the RPE of adult hamsters that had been exposed to intense light, premelanosomes containing unmelanised filaments with a striated periodicity were found in the cytoplasm or in association with mature melanin granules. Early and late stage melanosomes were also present. Phagosomes in the RPE contained degraded disk membranes, melanin-like material and melanofilaments. 6. Dopa oxidase was detected ultrastructurally within shed disk membranes that were in close contact with the microvilli of the RPE. 7. The possibility of melanogenesis within phagosomes during disk membrane degradation is discussed.

1. Endogenous peroxidase was localized by electron microscopy within the retinal tissue of the golden Syrian hamster. 2. Peroxidase activity was found in the apical parts of rod outer segments, in the cytoplasm and phagosomes of the retinal pigment epithelium (RPE), and extracellularly between the basal infoldings of the RPE. 3. No reaction product was detected when either H2O2 or tetramethyl benzidine were omitted from the reaction medium. 4. The same was true when the tissue was osmicated before the incubation in the reaction medium or treated with 100 mM sodium azide. 5. These results indicate that the peroxidatic activity was enzymatically mediated.

1. Rhabdomeral microvilli of photoreceptor cells of invertebrates contain a labile central cytoskeleton. For stabilization of the rhabdomeral cytoskeleton of the crayfish Orconectes limosus the crosslinking reagent suberic acid bis (N-hydroxysuccinimide ester) was used. 2. It was found that this crosslinking reagent can be successfully used to stabilize and isolate the microvillar cytoskeleton of crayfish photoreceptors. 3. After detergent treatment cytosolic proteins and the cell membranes were removed. 4. By the combined use of crosslinker and detergent the accessibility of antibodies or other markers to the microvillar cytoskeleton is possible. 5. This method may be useful, because at present little is known about the proteins associated with the central filament of invertebrate photoreceptors.