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Article: Factors affecting the cleavage efficiency of the CRISPR-Cas9 system.

Jung, Won Jun / Park, Soo-Ji / Cha, Seongkwang / Kim, Kyoungmi

2024 Volume 28, Issue 1, Page(s) 75–83

Abstract: The CRISPR-Cas system stands out as a promising genome editing tool due to its cost-effectiveness and time efficiency compared to other methods. This system has tremendous potential for treating various diseases, including genetic disorders and cancer, ... ...

Abstract	The CRISPR-Cas system stands out as a promising genome editing tool due to its cost-effectiveness and time efficiency compared to other methods. This system has tremendous potential for treating various diseases, including genetic disorders and cancer, and promotes therapeutic research for a wide range of genetic diseases. Additionally, the CRISPR-Cas system simplifies the generation of animal models, offering a more accessible alternative to traditional methods. The CRISPR-Cas9 system can be used to cleave target DNA strands that need to be corrected, causing double-strand breaks (DSBs). DNA with DSBs can then be recovered by the DNA repair pathway that the CRISPR-Cas9 system uses to edit target gene sequences. High cleavage efficiency of the CRISPR-Cas9 system is thus imperative for effective gene editing. Herein, we explore several factors affecting the cleavage efficiency of the CRISPR-Cas9 system. These factors include the GC content of the protospacer-adjacent motif (PAM) proximal and distal regions, single-guide RNA (sgRNA) properties, and chromatin state. These considerations contribute to the efficiency of genome editing.
Language	English
Publishing date	2024-03-03
Publishing country	England
Document type	Journal Article ; Review
ZDB-ID	2562988-8
ISSN	2151-2485 ; 1976-8354
ISSN (online)	2151-2485
ISSN	1976-8354
DOI	10.1080/19768354.2024.2322054
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Article ; Online: High amplitude pulses on the same charge condition efficiently elicit bipolar cell-mediated retinal ganglion cell responses in the degenerate retina.

Ahn, Jungryul / Jeong, Yurim / Cha, Seongkwang / Lee, Joo Yong / Yoo, Yongseok / Goo, Yong Sook

Biomedical engineering letters

2023 Volume 13, Issue 2, Page(s) 129–140

Abstract: Retinal pigmentosa (RP) patients lose vision due to the loss of photoreceptors. Retinal prostheses bypass the dead photoreceptors by electrically stimulating surviving retinal neurons, such as bipolar cells or retinal ganglion cells (RGCs). In previous ... ...

Abstract	Retinal pigmentosa (RP) patients lose vision due to the loss of photoreceptors. Retinal prostheses bypass the dead photoreceptors by electrically stimulating surviving retinal neurons, such as bipolar cells or retinal ganglion cells (RGCs). In previous studies, stimulus charge has been mainly optimized to maximize the RGC response to electrical stimulation. This study aimed to investigate the effect of amplitude and duration even under the same charge condition on eliciting RGC spikes in the wild-type and degenerate retinas. Wild-type (WT) Sprague-Dawley rats were used as the normal retinal model, and
Language	English
Publishing date	2023-01-31
Publishing country	Germany
Document type	Journal Article
ZDB-ID	2602422-6
ISSN	2093-985X ; 2093-9868
ISSN (online)	2093-985X
ISSN	2093-9868
DOI	10.1007/s13534-023-00260-4
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Article: Correlated Activity in the Degenerate Retina Inhibits Focal Response to Electrical Stimulation.

Ahn, Jungryul / Cha, Seongkwang / Choi, Kwang-Eon / Kim, Seong-Woo / Yoo, Yongseok / Goo, Yong Sook

Frontiers in cellular neuroscience

2022 Volume 16, Page(s) 889663

Abstract: Retinal prostheses have shown some clinical success in patients with retinitis pigmentosa and age-related macular degeneration. However, even after the implantation of a retinal prosthesis, the patient's visual acuity is at best less than 20/420. Reduced ...

Abstract	Retinal prostheses have shown some clinical success in patients with retinitis pigmentosa and age-related macular degeneration. However, even after the implantation of a retinal prosthesis, the patient's visual acuity is at best less than 20/420. Reduced visual acuity may be explained by a decrease in the signal-to-noise ratio due to the spontaneous hyperactivity of retinal ganglion cells (RGCs) found in degenerate retinas. Unfortunately, abnormal retinal rewiring, commonly observed in degenerate retinas, has rarely been considered for the development of retinal prostheses. The purpose of this study was to investigate the aberrant retinal network response to electrical stimulation in terms of the spatial distribution of the electrically evoked RGC population. An 8 × 8 multielectrode array was used to measure the spiking activity of the RGC population. RGC spikes were recorded in wild-type [C57BL/6J; P56 (postnatal day 56)],
Language	English
Publishing date	2022-05-04
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2452963-1
ISSN	1662-5102
ISSN	1662-5102
DOI	10.3389/fncel.2022.889663
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Article: The Variation of Electrical Pulse Duration Elicits Reliable Network-Mediated Responses of Retinal Ganglion Cells in Normal, Not in Degenerate Primate Retinas.

Cha, Seongkwang / Ahn, Jungryul / Kim, Seong-Woo / Choi, Kwang-Eon / Yoo, Yongseok / Eom, Heejong / Shin, Donggwan / Goo, Yong Sook

Bioengineering (Basel, Switzerland)

2023 Volume 10, Issue 10

Abstract: This study aims to investigate the efficacy of electrical stimulation by comparing network-mediated RGC responses in normal and degenerate retinas using a N-methyl-N-nitrosourea (MNU)-induced non-human primate (NHPs) retinitis pigmentosa (RP) model. ... ...

Abstract	This study aims to investigate the efficacy of electrical stimulation by comparing network-mediated RGC responses in normal and degenerate retinas using a N-methyl-N-nitrosourea (MNU)-induced non-human primate (NHPs) retinitis pigmentosa (RP) model. Adult cynomolgus monkeys were used for normal and outer retinal degeneration (RD) induced by MNU. The network-mediated RGC responses were recorded from the peripheral retina mounted on an 8 × 8 multielectrode array (MEA). The amplitude and duration of biphasic current pulses were modulated from 1 to 50 μA and 500 to 4000 μs, respectively. The threshold charge density for eliciting a network-mediated RGC response was higher in the RD monkeys than in the normal monkeys (1.47 ± 0.13 mC/cm
Language	English
Publishing date	2023-09-27
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2746191-9
ISSN	2306-5354
ISSN	2306-5354
DOI	10.3390/bioengineering10101135
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Article ; Online: Focal stimulation of retinal ganglion cells using subretinal 3D microelectrodes with peripheral electrodes of opposite current.

Seo, Hee Won / Cha, Seongkwang / Jeong, Yurim / Ahn, Jungryul / Lee, Kyeong Jae / Kim, Sohee / Goo, Yong Sook

Biomedical engineering letters

2023 Volume 14, Issue 2, Page(s) 355–365

Abstract: Subretinal prostheses have been developed to stimulate survived retinal ganglion cells (RGCs), indirectly following the physiological visual pathways. However, current spreading from the prosthesis electrode causes the activation of unintended RGCs, ... ...

Abstract	Subretinal prostheses have been developed to stimulate survived retinal ganglion cells (RGCs), indirectly following the physiological visual pathways. However, current spreading from the prosthesis electrode causes the activation of unintended RGCs, thereby limiting the spatial resolution of artificial vision. This study proposes a strategy for focal stimulation of RGCs using a subretinal electrode array, in which six hexagonally arranged peripheral electrodes surround a stimulating electrode. RGCs in an in-vitro condition were subretinally stimulated using a fabricated electrode array coated with iridium oxide, following the three different stimulation configurations (with no peripheral, six electrodes of opposite current, and six ground). In-vitro experiments showed that the stimulation with six electrodes of opposite current was most effective in controlling RGC responses with a high spatial resolution. The results suggest that the effective utilization of return electrodes, such as by applying an opposite current to them, could help reduce current spreading beyond the local area targeted for stimulation and elicit RGC responses only in the vicinity of the stimulating electrode. Supplementary information: The online version contains supplementary material available at 10.1007/s13534-023-00342-3.
Language	English
Publishing date	2023-12-26
Publishing country	Germany
Document type	Journal Article
ZDB-ID	2602422-6
ISSN	2093-985X ; 2093-9868
ISSN (online)	2093-985X
ISSN	2093-9868
DOI	10.1007/s13534-023-00342-3
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Article: Stage-Dependent Changes of Visual Function and Electrical Response of the Retina in the

Cha, Seongkwang / Ahn, Jungryul / Jeong, Yurim / Lee, Yong Hee / Kim, Hyong Kyu / Lee, Daekee / Yoo, Yongseok / Goo, Yong Sook

Frontiers in cellular neuroscience

2022 Volume 16, Page(s) 926096

Abstract: One of the critical prerequisites for the successful development of retinal prostheses is understanding the physiological features of retinal ganglion cells (RGCs) in the different stages of retinal degeneration (RD). This study used our custom- ... ...

Abstract	One of the critical prerequisites for the successful development of retinal prostheses is understanding the physiological features of retinal ganglion cells (RGCs) in the different stages of retinal degeneration (RD). This study used our custom-made
Language	English
Publishing date	2022-07-19
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2452963-1
ISSN	1662-5102
ISSN	1662-5102
DOI	10.3389/fncel.2022.926096
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Article: Synchrony of Spontaneous Burst Firing between Retinal Ganglion Cells Across Species.

Ahn, Jungryul / Phan, Huu Lam / Cha, Seongkwang / Koo, Kyo-In / Yoo, Yongseok / Goo, Yong Sook

Experimental neurobiology

2020 Volume 29, Issue 4, Page(s) 285–299

Abstract: Neurons communicate with other neurons in response to environmental changes. Their goal is to transmit information to their targets reliably. A burst, which consists of multiple spikes within a short time interval, plays an essential role in enhancing ... ...

Abstract	Neurons communicate with other neurons in response to environmental changes. Their goal is to transmit information to their targets reliably. A burst, which consists of multiple spikes within a short time interval, plays an essential role in enhancing the reliability of information transmission through synapses. In the visual system, retinal ganglion cells (RGCs), the output neurons of the retina, show bursting activity and transmit retinal information to the lateral geniculate neuron of the thalamus. In this study, to extend our interest to the population level, the burstings of multiple RGCs were simultaneously recorded using a multi-channel recording system. As the first step in network analysis, we focused on investigating the pairwise burst correlation between two RGCs. Furthermore, to assess if the population bursting is preserved across species, we compared the synchronized bursting of RGCs between marmoset monkey (callithrix jacchus), one species of the new world monkeys and mouse (C57BL/6J strain). First, monkey RGCs showed a larger number of spikes within a burst, while the inter-spike interval, burst duration, and inter-burst interval were smaller compared with mouse RGCs. Monkey RGCs showed a strong burst synchronization between RGCs, whereas mouse RGCs showed no correlated burst firing. Monkey RGC pairs showed significantly higher burst synchrony and mutual information than mouse RGC pairs did. Comprehensively, through this study, we emphasize that two species have a different bursting activity of RGCs and different burst synchronization suggesting two species have distinctive retinal processing.
Language	English
Publishing date	2020-09-14
Publishing country	Korea (South)
Document type	Journal Article
ZDB-ID	2639017-6
ISSN	2093-8144 ; 1226-2560
ISSN (online)	2093-8144
ISSN	1226-2560
DOI	10.5607/en20025
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Article ; Online: Outer retinal degeneration in a non-human primate model using temporary intravitreal tamponade with N-methyl-N-nitrosourea in cynomolgus monkeys.

Choi, Kwang-Eon / Cha, Seongkwang / Yun, Cheolmin / Ahn, Jungryul / Hwang, Seil / Kim, Young-Jin / Jung, Hachul / Eom, Heejong / Shin, Dongkwan / Oh, Jaeryung / Goo, Yong Sook / Kim, Seong-Woo

Journal of neural engineering

2023 Volume 20, Issue 1

Abstract: Objective: ...

Abstract	Objective:
MeSH term(s)	Animals ; Retinal Degeneration ; Macaca fascicularis ; Methylnitrosourea/adverse effects ; Evoked Potentials, Visual ; Retina/pathology ; Primates ; Tomography, Optical Coherence/methods
Chemical Substances	Methylnitrosourea (684-93-5)
Language	English
Publishing date	2023-01-20
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2170901-4
ISSN	1741-2552 ; 1741-2560
ISSN (online)	1741-2552
ISSN	1741-2560
DOI	10.1088/1741-2552/acb085
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Article ; Online: An experimental pig model with outer retinal degeneration induced by temporary intravitreal loading of N-methyl-N-nitrosourea during vitrectomy.

Choi, Kwang-Eon / Anh, Vu Thi Que / Kim, Jee Taek / Yun, Cheolmin / Cha, Seongkwang / Ahn, Jungryul / Goo, Yong Sook / Kim, Seong-Woo

Scientific reports

2021 Volume 11, Issue 1, Page(s) 258

Abstract: We aimed to develop an outer retinal degeneration pig model induced by temporary intravitreal loading of N-methyl-N-nitrosourea (MNU) during vitrectomy. In a preliminary experiment involving 5 mini-pig cases to determine the appropriate concentration of ... ...

Abstract	We aimed to develop an outer retinal degeneration pig model induced by temporary intravitreal loading of N-methyl-N-nitrosourea (MNU) during vitrectomy. In a preliminary experiment involving 5 mini-pig cases to determine the appropriate concentration of MNU, the vitreous cavity of each eye was filled with 4, 8, 10, 12, or 16 mg/mL MNU for 10 min, which was then replaced with a balanced salt solution. Multimodal examinations including spectral-domain optical coherence tomography (OCT) images and full-field electroretinography (ffERG) were obtained at baseline and week 2, week 6, and week 12. The retinal degeneration was classified according to the amplitudes of a dark adaptive (DA) 10.0 a-wave amplitude. The degree of moderate retinal degeneration was defined as DA 10.0 a-wave amplitude ≥ 10% and < 60% of baseline amplitude. The degree of severe degeneration was defined as DA 10.0 a-wave amplitude < 10% of baseline amplitude, noise, or flat signal. Hematoxylin and eosin staining and immunohistochemistry were performed at week 12. The main experiments were conducted first with 10 cases of 5 mg/mL and later with 13 cases of 10 mg/mL. In the preliminary experiment, degree of outer retinal degeneration increased with MNU concentration. Use of 4, 8, 10, 12, and 16 mg/mL MNU showed no, moderate, severe, severe, and atrophic changes, respectively. In the main experiments, there were 9 cases of moderate retinal degeneration and 1 case of severe degeneration in 5 mg/mL MNU group. Two cases of moderate degeneration and 11 of severe degeneration were recorded in 10 mg/mL group. Mean thickness of total retina, inner nuclear layer, and outer nuclear layer decreased at week 2 in both groups. The mean amplitudes on ffERG decreased at week 2. The ffERG and OCT findings did not change from week 2 to week 6 or week 12. The results of staining supported those of ffERG and OCT. Temporal MNU loading in a vitrectomized pig-eye model induced customized outer retinal degeneration with changing the concentration of MNU.
MeSH term(s)	Animals ; Disease Models, Animal ; Dose-Response Relationship, Drug ; Electroretinography ; Intravitreal Injections ; Methylnitrosourea/toxicity ; Retinal Degeneration/chemically induced ; Retinal Degeneration/diagnostic imaging ; Retinal Degeneration/pathology ; Swine ; Swine, Miniature ; Tomography, Optical Coherence ; Vitrectomy/methods
Chemical Substances	Methylnitrosourea (684-93-5)
Language	English
Publishing date	2021-01-08
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/s41598-020-79437-1
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Article ; Online: Electrical response of retinal ganglion cells in an N-methyl-N-nitrosourea-induced retinal degeneration porcine model.

Cha, Seongkwang / Choi, Kwang-Eon / Ahn, Jungryul / Yoo, Minsu / Jeong, Yurim / Kim, Seong-Woo / Goo, Yong Sook

Scientific reports

2021 Volume 11, Issue 1, Page(s) 24135

Abstract: Retinal prosthesis is regarded as the treatment for vision restoration in the blind with retinal degeneration (RD) due to the loss of photoreceptors. A strategy for retinal prosthesis is to electrically activate surviving neurons. The retina's response ... ...

Abstract	Retinal prosthesis is regarded as the treatment for vision restoration in the blind with retinal degeneration (RD) due to the loss of photoreceptors. A strategy for retinal prosthesis is to electrically activate surviving neurons. The retina's response to electrical stimulation in a larger RD model has not been studied yet. Therefore, in this study, we investigated electrically evoked retinal responses in a previously validated N-methyl-N-nitrosourea (MNU)-induced porcine RD model. Electrically evoked responses were evaluated based on the number of retinal ganglion cell (RGC) spikes via multichannel recordings. Stimulation pulses were applied to degenerative and wild-type retinas with pulse modulation. Compared to wild-type retinas, degenerative retinas showed higher threshold values of pulse amplitude and pulse duration. The rate of increase in the number of RGC spikes relative to stimulus intensity was lower in degenerative retinas than in normal retinas. In severely degenerated retinas, few RGCs showed electrically evoked spikes. Our results suggest that the degenerative porcine retina requires a higher charge than the normal porcine retina. In the early stage of RD, it is easier to induce RGC spikes through electrical stimulation using retinal prosthesis; however, when the degeneration is severe, there may be difficulty recovering patient vision.
MeSH term(s)	Animals ; Disease Models, Animal ; Electric Stimulation ; Evoked Potentials, Visual/drug effects ; Female ; Methylnitrosourea/toxicity ; Retinal Degeneration/chemically induced ; Retinal Degeneration/metabolism ; Retinal Degeneration/physiopathology ; Retinal Ganglion Cells/metabolism ; Swine ; Swine, Miniature
Chemical Substances	Methylnitrosourea (684-93-5)
Language	English
Publishing date	2021-12-17
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/s41598-021-03439-w
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