• Polymer(Korea)
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• v.38 no.3
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• pp.364-370
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• 2014

The retinal pigment epithelium (RPE) plays an important role in maintaining a healthy retina and the degeneration of RPE caused a number of retinal diseases. The transplantation of RPE has recently become a possible therapeutic modality for retinal degeneration. To transplant RPE cells securely, substrates are essential, and then as a substrate, we fabricated films using silk that has unique mechanical properties and biocompatibility. After the FTIR spectra, contact angle and biodegradation of silk films were confirmed, RPE cells were seeded and the influence of RPE cells on silk films was examined. We measured the cell adhesion, cell viability, morphology and specific mRNA expression by MTT assay, SEM, immunofluorescence and RT-PCR. In this study, we confirmed that attachment, proliferation and phenotype maintenance of RPE cells cultured on silk films were great, and thereby we were able to confirm the potential applications of silk films as tissue engineering carrier for regeneration of retina.

• Polymer(Korea)
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• v.38 no.1
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• pp.24-30
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• 2014

Retinal pigment epithelium (RPE) plays an important role in maintaining the visual function and the degeneration of the RPE causes several retinal degeneration disease. In order to fabricate the suitable carrier for RPE transplantation, the hybrid poly(lactide-co-glycolide) (PLGA) film with hesperidin was prepared. Hesperidin has an anti-inflammatory and antioxidant characteristics. ARPE-19 was seeded on hesperidin/PLGA film and then, cell proliferation was determined by the MTT assay, and cell adhesion and cell morphology were confirmed by SEM. Also, RT-PCR was performed to confirm the expression of the specific genes, and AEC immunohistochemical staining was performed to determine the expression of RPE65. As a result, we confirmed that attachment, proliferation and phenotype maintenance of RPE cells were more excellent on hesperidin/PLGA film than PLGA film, thereby we were able to confirm the potential applications of hesperidin/PLGA film as tissue engineering carrier for regeneration of retina.

• BMB Reports
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• v.47 no.5
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• pp.292-297
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• 2014

Age-related macular degeneration (AMD) is the leading cause of blindness in the world. Evidence indicates that the suppression of the ubiquitin-proteasome system (UPS) contributes to the accumulation of toxic proteins and inflammation in retinal pigment epithelium (RPE), the functional abnormalities and/or the degeneration of which are believed to be the initiators and major pathologies of AMD. To identify new protein associations with the altered UPS in AMD, we used LC-ESI-MS/MS to perform a proteomic analysis of the aqueous humor (AH) of AMD patients and matched control subjects. Six UPS-related proteins were present in the AH of the patients and control subjects. Four of the proteins, including 26S proteasome non-ATPase regulatory subunit 1 (Rpn2), were increased in patients, according to semi-quantitative proteomic profiling. An LC-MRM assay revealed a significant increase of Rpn2 in 15 AMD patients compared to the control subjects, suggesting that this protein could be a biomarker for AMD.

• Journal of Nutrition and Health
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• v.38 no.2
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• pp.96-103
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• 2005

It has been suggested that the elevated plasma homocysteine may lead to retinal dysfunction. We investigated the effects of plasma levels of homocysteine and folate on the retinal glial cells' injuries. Male Sprague-Dawley rats were raised either on a control diet or on an experimental diet containing 3.0 g/kg homocystine without folic acid for 10 weeks. Plasma homocysteine concentrations were measured by a HPLC-fluorescence detection method. Plasma folate and vitamin B/sub 12/ levels were analyzed by a radioimmunoassay. The response of Muller cells which are the principal glial cells of the retina was immunohistochemically examined using an antibody for vimentin, a cytoskeletal protein belonging to the family of intermediate filament. At 2 weeks, the homocystine diet induced a twofold increase in plasma homocysteine, and a concomitant increase in the expression of vimentin in the Muller cells' processes spanning from the inner to outer membranes of the retina indicating arterial degeneration. At 10 weeks, the homocystine diet induced a fourfold increase in plasma homocystine, but vimentin immunoreactivity in the retinas was similar in both groups. In conclusion, increased plasma homocysteine levels have influence on morphological and functional changes of Muller cells in the retina. (Korean J Nutrition 38(2): 96～103, 2005)

• BMB Reports
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• v.51 no.7
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• pp.315-316
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• 2018

Genome engineering with clustered regularly interspaced short palindromic repeats (CRISPR) system can be used as a tool to correct pathological mutations or modulate gene expression levels associated with pathogenesis of human diseases. Owing to well-established local administration methods including intravitreal and subretinal injection, it is relatively easy to administer therapeutic genome engineering machinery to ocular tissues for treating retinal diseases. In this context, we have investigated the potential of in vivo genome engineering as a therapeutic approach in the form of ribonucleoprotein or CRISPR packaged in viral vectors. Major issues in therapeutic application of genome engineering include specificity and efficacy according to types of CRISPR system. In addition to previous platforms based on ribonucleoprotein and CRISPR-associated protein 9 derived from Campylobacter jejuni, we evaluated the therapeutic effects of a CRISPR RNA-guided endonuclease derived from Lachnospiraceae bacterium ND2006 (LbCpf1) in regulating pathological angiogenesis in an animal model of wet-type age-related macular degeneration. LbCpf1 targeting Vegfa or Hif1a effectively disrupted the expression of genes in ocular tissues, resulting in suppression of choroidal neovascularization. It was also notable that there were no significant off-target effects in vivo.

• Journal of Korea Multimedia Society
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• v.22 no.11
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• pp.1269-1279
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• 2019

In medical image analysis, segmentation is considered as a vital process since it partitions an image into coherent parts and extracts interesting objects from the image. In this paper, we consider automatic segmentations of OCT retinal images to find six layer boundaries using convolutional neural networks. Segmenting retinal images by layer boundaries is very important in diagnosing and predicting progress of eye diseases including diabetic retinopathy, glaucoma, and AMD (age-related macular degeneration). We applied well-known CNN architecture for general image segmentation, called Segnet, U-net, and CNN-S into this problem. We also proposed a shortest path-based algorithm for finding the layer boundaries from the outputs of Segnet and U-net. We analysed their performance on public OCT image data set. The experimental results show that the Segnet combined with the proposed shortest path-based boundary finding algorithm outperforms other two networks.

• Molecules and Cells
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• v.44 no.8
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• pp.613-622
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• 2021

In vertebrate eyes, the retinal pigment epithelium (RPE) provides structural and functional homeostasis to the retina. The RPE takes up retinol (ROL) to be dehydrogenated and isomerized to 11-cis-retinaldehyde (11-cis-RAL), which is a functional photopigment in mammalian photoreceptors. As excessive ROL is toxic, the RPE must also establish mechanisms to protect against ROL toxicity. Here, we found that the levels of retinol dehydrogenases (RDHs) are commonly decreased in phosphatase tensin homolog (Pten)-deficient mouse RPE, which degenerates due to elevated ROL and that can be rescued by feeding a ROL-free diet. We also identified that RDH gene expression is regulated by forkhead box O (FOXO) transcription factors, which are inactivated by hyperactive Akt in the Pten-deficient mouse RPE. Together, our findings suggest that a homeostatic pathway comprising PTEN, FOXO, and RDH can protect the RPE from ROL toxicity.

• Journal of Genetic Medicine
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• v.10 no.1
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• pp.13-19
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• 2013

Retinitis pigmentosa (RP) is the most common hereditary retinal disorder and is characterized by progressive retinal degeneration and decline in vision. RP comprises a heterogeneous group of disorders caused by various genetic variants. Since the first discovery of the causal mutation in the RHO gene using positional cloning, numerous mutations have been detected in more than 60 loci and 50 genes. However, causal genes have not been discovered in about 50% of cases. We attempt here to review the strategies to identify causal alleles of retinitis pigmentosa. These include conventional methods as well as state-of-the-art technologies based on next-generation sequencing.

• Progress in Medical Physics
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• v.19 no.3
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• pp.157-163
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• 2008

Retinal prosthesis is regarded as the most feasible method for the blind caused by retinal diseases such as retinitis pigmentosa or age-related macular degeneration. One of the prerequisites for the success of retinal prosthesis is the optimization of the electrical stimuli applied through the prosthesis. Since electrical characteristics of degenerate retina are expected to differ from those of normal retina, we investigated differences of the retinal waveforms in normal and degenerate retina to provide a guideline for the optimization of electrical stimulation for the upcoming prosthesis. After isolation of retina, retinal patch was attached with the ganglion cell side facing the surface of microelectrode arrays (MEA). $8{\times}8$ grid layout MEA (electrode diameter: $30{\mu}m$, electrode spacing: $200{\mu}m$, and impedance: 50 $k{\Omega}$ at 1 kHz) was used to record in-vitro retinal ganglion cell activity. In normal mice (C57BL/6J strain) of postnatal day 28, only short duration (<2 ms) retinal spikes were recorded. In rd/rd mice (C3H/HeJ strain), besides normal spikes, waveform with longer duration (~100 ms), the slow wave component was recorded. We attempted to understand the mechanism of this slow wave component in degenerate retina using various synaptic blockers. We suggest that stronger glutamatergic input from bipolar cell to the ganglion cell in rd/rd mouse than normal mouse contributes the most to this slow wave component. Out of many degenerative changes, we favor elimination of the inhibitory horizontal input to bipolar cells as a main contributor for a relatively stronger input from bipolar cell to ganglion cell in rd/rd mouse.

• Journal of Veterinary Clinics
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• v.24 no.2
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• pp.154-159
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• 2007

The objective of this retrospective study was to investigate the prevalence of retinal diseases in dogs presented to the Veterinary Medical Teaching Hospital, Seoul National University from April 2004 to December 2005. Sixty-five dogs (120 eyes) with retinal diseases involving blindness were included in this study. Age, breed, and gender data for all breeds were collected from medical records documenting vision loss. Generalized progressive retinal atrophy (gPRA) was the most common manifestation. Other prevalent findings included sudden acquired retinal degeneration (SARD) and retinal detachment (RD). Bilateral gPRA was found in 32 dogs with a female-to-male ratio of 1 : 1. The mean $age{\pm}SD$ of all dogs in this group was $4.66{\pm}2.30$ years with a range of 3 to 12 years. Breeds with highest prevalence of gPRA were Miniature Schnauzer (24/32, $mean{\pm}SD$ age: $3.79{\pm}0.78$ yr) and Poodle (2/32, $6.50{\pm}0.71$ yr). Twelve dogs (24 eyes) were diagnosed with SARD bilateraly, ranging from 3 to 13 years of age ($mean{\pm}SD:\;6.91{\pm}2.61$ yr). There were no abnormalities in fundus of 11 dogs at presentation. Electroretinography (ERG) without anesthesia was performed in 7 dogs, and all response was totally extinguished. Retinal detachment was identified in 21 dogs (32 eyes): 11 bilateral and 10 unilateral (7 right eye, 3 left eye). The most common breed was Shih Tzu (15/21, $mean{\pm}SD$ age: $4.39{\pm}3.24$ yr). Four other breeds comprised the remaining 6 cases (8 eyes). The everall mean age of the group was: $4.18{\pm}2.89$ years (range 0.8 to 14 years) with a female-to-male ratio of 1 : 1.1 (10 females, and 11 males).