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Purpose: Dysfunction of the retinal pigment epithelium (RPE) causes numerous forms of retinal degeneration. RPE replacement is a modern option to save vision. We aimed to test the results of transplanting cultured RPEs on biocompatible membranes. Methods: We cultivated porcine primary RPE cells isolated from cadaver eyes from the slaughterhouse on two types of membranes: commercial polyester scaffolds Transwell (Corning Inc., Kenneburg, ME, USA) with 0.4 µm pore size and prepared Poly (L‐lactide‐co‐DL‐lactide) (PDLLA) nanofibrous membranes with an average pore size of 0.4 µm. Results: Five types of assays were used for the analysis: immunocytochemistry (ICC), phagocytosis assay, Western blotting, real‐time qPCR (RT‐qPCR) and electron microscopy. RT‐qPCR demonstrated that RPEs cultured on nanofibrous membranes have higher expressions of BEST1 (bestrophin 1), RLBP1 (retinaldehyde‐binding protein 1), RPE65 (retinal pigment epithelium‐specific 65 kDa protein), PAX6 (transcription factor PAX6), SOX9 (transcription factor SOX9), DCT (dopachrome tautomerase) and MITF (microphthalmia‐associated transcription factor). ICC of the RPEs cultured on nanofibrous membranes showed more intensive staining of markers such as BEST1, MCT1 (monocarboxylate transporter 1), Na+/K+ATPase, RPE65 and acetylated tubulin in comparison with commercial ones. Additionally, the absence of α‐SMA proved the stability of the RPE polarization state and the absence of epithelial‐to‐mesenchymal transition. RPE possessed high phagocytic activity. Electron microscopy of both membranes confirmed a confluent layer of RPE cells and their genuine morphological structure, which was comparable to native RPEs. Conclusions: Retinal pigment epitheliums cultured on polylactide nanofibrous membranes improved the final quality of the cell product by having better maturation and long‐term survival of the RPE monolayer compared to those cultured on commercial polyester scaffolds. PDLLA‐cultured RPEs are a plausible source for the replacement of non‐functioning RPEs during cell therapy. [ABSTRACT FROM AUTHOR]

Purpose: Exposure of the cornea to UV radiation from sunlight evokes intraocular inflammation, photokeratitis. Photokeratitis is caused by UVB radiation. It is accompanied by changes of corneal hydration and light absorption. The aim of this study was to examine the effect of two UVB doses on corneal optics in rabbits and to compare these UVB doses with the equivalent exposure of UVB radiation reaching the human cornea from sunlight. Materials and Methods: Rabbit corneas were irradiated with a daily UVB dose of 0.25 J/cm2 or 0.5 J/cm2 for 4 days. One day after finishing the irradiations the rabbits were sacrificed and corneal light absorption measured using our spectrophotometrical method. Corneal hydration was examined using an ultrasonic Pachymeter every experimental day before the irradiation procedure and the last day before sacrificing the animals. Results: Changes in corneal optics appeared after the repeated exposure of the cornea to a UVB dose of 0.25 J/ cm2 and massively increased after the repeated exposure of the cornea to a UVB dose of 0.5 J/cm2. The first significant changes in corneal hydration appeared after a single exposure of the cornea to a UVB dose of 0.25 J/cm2. Conclusions: Changes in corneal hydration appeared after the exposure of the rabbit cornea to a single UVB dose equivalent to 2.6 hours of solar UVB radiation reaching the human cornea, as measured by UVB sensors embedded in the eyes of mannequin heads facing the sun on a beach at noon in July. Repeated exposure of the rabbit cornea to the same UVB dose evoked profound changes in corneal optics. Although comparison of experimental and outdoor conditions are only approximate, the results in rabbits point to the danger for the human eye from UVB radiation when short stays in sunlight are repeated for several consecutive days without UV protection. [ABSTRACT FROM AUTHOR]

Purpose: Subretinal (SR) injection in porcine models is a promising avenue for preclinical evaluation of cell and gene therapies. Targeting of the subretinal fluid compartment (bleb) is critical to the procedure, especially if treatment of the cone-rich area centralis is required (i.e., visual streak [VS] in pigs). To our knowledge, this study is the first to investigate the influence of injection site placement on VS involvement in the pig eye., Methods: We performed 23-gauge pars plana vitrectomy followed by SR injection in 41 eyes of 21 animals (Sus scrofa domesticus). In 27 eyes (65.9%), the injection site was placed superior to the VS, and in 14 eyes (34.1%) it was placed inferior to it. Using intraoperative imaging, blebs were classified based on their propagation behavior relative to the VS., Results: In 79% of cases, blebs from inferior injection sites developed away from the VS, exhibiting a mean ± SEM vertical anisotropy (AP) of 0.67 ± 0.11. In contrast, blebs from superior injection sites tended to develop toward the VS with an AP of 1.27 ± 0.18 (P = 0.0070). Blebs developed away from the VS in only 41% of injections (P = 0.0212). Inferior blebs were orientated close to 0° (horizontal), whereas superior blebs displayed varied orientations with a mean angle of 56° (P = 0.0008)., Conclusions: Bleb propagation was anisotropic (i.e., directionally biased) and dependent on injection site placement. Superior injection sites led to superior VS detachment. Morphological analysis suggested increased adhesion forces at the VS and superior vascular arcades. This study will aid the planning of surgeries for targeted subretinal delivery in pig models.

Purpose: Exposure of the cornea to UV radiation from sunlight evokes intraocular inflammation, photokeratitis. Photokeratitis is caused by UVB radiation. It is accompanied by changes of corneal hydration and light absorption. The aim of this study was to examine the effect of two UVB doses on corneal optics in rabbits and to compare these UVB doses with the equivalent exposure of UVB radiation reaching the human cornea from sunlight., Materials and Methods: Rabbit corneas were irradiated with a daily UVB dose of 0.25 J/cm(2) or 0.5 J/cm(2) for 4 days. One day after finishing the irradiations the rabbits were sacrificed and corneal light absorption measured using our spectrophotometrical method. Corneal hydration was examined using an ultrasonic Pachymeter every experimental day before the irradiation procedure and the last day before sacrificing the animals., Results: Changes in corneal optics appeared after the repeated exposure of the cornea to a UVB dose of 0.25 J/ cm(2) and massively increased after the repeated exposure of the cornea to a UVB dose of 0.5 J/cm(2). The first significant changes in corneal hydration appeared after a single exposure of the cornea to a UVB dose of 0.25 J/cm(2)., Conclusions: Changes in corneal hydration appeared after the exposure of the rabbit cornea to a single UVB dose equivalent to 2.6 hours of solar UVB radiation reaching the human cornea, as measured by UVB sensors embedded in the eyes of mannequin heads facing the sun on a beach at noon in July. Repeated exposure of the rabbit cornea to the same UVB dose evoked profound changes in corneal optics. Although comparison of experimental and outdoor conditions are only approximate, the results in rabbits point to the danger for the human eye from UVB radiation when short stays in sunlight are repeated for several consecutive days without UV protection.

Trehalose, a nonreducing disaccharide of glucose, produced and stored in many lower and higher organisms, although not in mammals, is synthetized as a stress responsive factor when cells are exposed to various environmental stress conditions. Recently, trehalose has been implicated in various situations in mammals. The aim of this paper was to examine whether trehalose might decrease the damage of the rabbit cornea evoked by UVB rays. During irradiation with UVB rays, consisiting of a daily dose of 0.5 J/cm2 for four days, trehalose was applied in eye drops on the right eye and buffered saline on the left eye. One day after the end of irradiation the animals were sacrificed and the corneas examined spectrophotometrically for light absorption. Another group of corneas similarly treated were examined morphologically and immunohistochemically. Corneal thickness (hydration) was measured using a Pachymeter. The results show that compared to buffered saline, trehalose treated corneas displayed fewer corneal disturbances during UVB irradiation. The increases in corneal hydration and light absorption were less pronounced and intracorneal inflammation and corneal neovascularization were suppressed. Nitric oxide synthases that generate nitric oxide were less expressed in the cornea, and formation of cytotoxic peroxynitrite (demonstrated by nitrotyrosine residues) was decreased. The expression of the antioxidant aldehyde dehydrogenase3A1 was less inhibited in the corneal epithelium, and apoptotic corneal epithelial cell death (detected by immunostaining for active caspase-3) was greatly diminished. In conclusion, trehalose reduced UVB-induced damage caused by reactive oxygen and nitrogen species and decreased changes in the corneal optics.