Ikeda, Shin-ichi

写真a

Affiliation

School of Medicine, Department of Ophthalmology (Shinanomachi)

Position

Project Assistant Professor (Non-tenured)/Project Research Associate (Non-tenured)/Project Instructor (Non-tenured)

Career 【 Display / hide

  • 2008.04
    -
    2014.03

    Juntendo University Graduate School of Medicine, Department of Metabolism & Endocrinology, Post-doctoral fellow

  • 2014.04
    -
    2016.03

    Graduate School of Medicine, The University of Tokyo, Department of Gerontological Nursing/Wound Care Management, Assistant Professor

  • 2016.04
    -
    Present

    Keio University School of Medicine, Laboratory of Photobiology, Department of Ophthalmology, Assistant Professor

Academic Degrees 【 Display / hide

  • Ph.D., University of Tsukuba, Coursework, 2009.03

 

Research Areas 【 Display / hide

  • Ophthalmology

  • Environmental physiology (including physical medicine and nutritional physiology)

Research Keywords 【 Display / hide

  • Extracellular Matrix

  • cell-cell-communication

  • Tissue remodeling

  • Myopia

  • skeletal muscle

 

Papers 【 Display / hide

  • Estimation of the minimum effective dose of dietary supplement crocetin for prevention of myopia progression in mice

    Mori K., Kurihara T., Jiang X., Ikeda S., Yotsukura E., Torii H., Tsubota K.

    Nutrients (Nutrients)  12 ( 1 )  2020

     View Summary

    © 2020, MDPI AG. All rights reserved. The natural carotenoid crocetin has been reported to suppress phenotypes of an experimental myopia model in mice. We investigated the minimum effective dose to prevent myopia progression in a murine model. Three-week-old male mice (C57B6/J) were equipped with a −30 diopter (D) lens to induce myopia, and fed with normal chow, 0.0003%, or 0.001% of crocetin-containing chow. Changes in refractive errors and axial lengths (AL) were evaluated after three weeks. Pharmacokinetics of crocetin in the plasma and the eyeballs of mice was evaluated with specific high sensitivity quantitative analysis using liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine the minimum effective dosage. A concentration of 0.001% of crocetin-containing chow showed a significant (p < 0.001) suppressive effect against both refractive and AL changes in the murine model. Meanwhile, there was no significant difference of AL change between the 0.0003% and the normal chow groups. The concentration of crocetin in the plasma and the eyeballs from mice fed with 0.001% crocetin-containing chow was significantly higher than control and 0.0003% crocetin-containing chow. In conclusion, we suggest 0.001% of crocetin-containing extract is the minimum effective dose showing a significant suppressive effect against both refractive and AL changes in the murine model.

  • Oral crocetin administration suppressed refractive shift and axial elongation in a murine model of lens-induced myopia

    Mori K., Kurihara T., Miyauchi M., Ishida A., Jiang X., Ikeda S., Torii H., Tsubota K.

    Scientific Reports (Scientific Reports)  9 ( 1 )  2019.12

     View Summary

    © 2019, The Author(s). Increased global incidence of myopia necessitates establishment of therapeutic approaches against its progression. To explore agents which may control myopia, we screened 207 types of natural compounds and chemical reagents based on an activity of a myopia suppressive factor, early growth response protein 1 (Egr-1) in vitro. Among the candidates, crocetin showed the highest and dose-dependent activation of Egr-1. For in vivo analysis, experimental myopia was induced in 3-week-old C57BL/6 J mice with −30 diopter (D) lenses for 3 weeks. Animals were fed with normal or mixed chow containing 0.003% (n = 19) and 0.03% (n = 7) of crocetin during myopia induction. Refraction and axial length were measured at 3-week-old and the 6-week-old with an infrared photorefractor and a SD-OCT system. Compared to controls (n = 14), crocetin administration showed a significant smaller change of refractive errors (−13.62 ± 8.14 vs +0.82 ± 5.81 D for 0.003%, p < 0.01, −2.00 ± 4.52 D for 0.03%, p < 0.01) and axial elongation (0.27 ± 0.03 vs 0.22 ± 0.04 mm for 0.003%, p < 0.01, 0.23 ± 0.05 mm for 0.03%, p < 0.05). These results suggest that a dietary factor crocetin may have a preventive effect against myopia progression.

  • Effects of hyperoxia on the refraction in murine neonatal and adult models

    Mori K., Kurihara T., Jiang X., Ikeda S., Ishida A., Torii H., Tsubota K.

    International Journal of Molecular Sciences (International Journal of Molecular Sciences)  20 ( 23 )  2019.12

    ISSN  16616596

     View Summary

    © 2019 by the authors. Licensee MDPI, Basel, Switzerland. Whether hyperoxia affects the refraction in neonatal and adult mice is unknown. The mice exposed to 85% oxygen at postnatal 8 days (P8d) for 3 days and the mice exposed to normal air were assigned to the neonatal hyperoxia and normoxia groups, respectively. The refraction, the corneal curvature radius (CR) and the axial length (AL) were measured at P30d and P47d. Postnatal 6 weeks (P6w) adult mice were divided into the adult hyperoxia and normoxia groups. These parameters were measured before oxygen exposure, after 1 and 6 weeks, and every 7 weeks. The lens elasticity was measured at P7w and P26w by enucleation. The neonatal hyperoxia group showed a significantly larger myopic change than the neonatal normoxia group (P47d −6.56 ± 5.89 D, +4.11 ± 2.02 D, p < 0.001), whereas the changes in AL were not significantly different (P47d, 3.31 ± 0.04 mm, 3.31 ± 0.05 mm, p = 0.852). The adult hyperoxia group also showed a significantly larger myopic change (P12w, −7.20 ± 4.09 D, +7.52 ± 2.54 D, p < 0.001). The AL did not show significant difference (P12w, 3.44 ± 0.03 mm, 3.43 ± 0.01 mm, p = 0.545); however, the CR in the adult hyperoxia group was significantly smaller than the adult normoxia group (P12w, 1.44 ± 0.03 mm, 1.50 ± 0.03 mm, p = 0.003). In conclusion, hyperoxia was demonstrated to induce myopic shift both in neonatal and adult mice, which was attributed to the change in the CR rather than the AL. Elucidation of the mechanisms of hyperoxia and the application of this result to humans should be carried out in future studies.

  • Ocular-component-specific miRNA expression in a murine model of lens-induced myopia

    Tanaka Y., Kurihara T., Hagiwara Y., Ikeda S., Mori K., Jiang X., Torii H., Tsubota K.

    International Journal of Molecular Sciences (International Journal of Molecular Sciences)  20 ( 15 )  2019.08

    ISSN  16616596

     View Summary

    © 2019 by the authors. Licensee MDPI, Basel, Switzerland. To identify tissues and molecules involved in refractive myopic shift and axial length elongation in a murine lens-induced myopia model, we performed a comprehensive analysis of microRNA (miRNA) expression. Three weeks after negative 30 diopter lens fixation on three-week-old C57BL/6J mice, total RNA was extracted from individual ocular components including cornea, iris, lens, retina, retinal pigment epithelium (RPE)/choroid, and sclera tissue. The miRNA expression analysis was pooled from three samples and carried out using Agilent Mouse miRNA Microarray (8 × 60 K) miRBase21.0. The expression ratio was calculated, and differentially expressed miRNAs were extracted, using GeneSpring GX 14.5. Myopic induction showed a significant myopic refractive change, axial elongation, and choroidal thinning. Through the comprehensive miRNA analysis, several upregulated miRNAs (56 in cornea tissue, 13 in iris tissue, 6 in lens tissue, 0 in retina tissue, 29 in RPE/choroid tissue, and 30 in sclera tissue) and downregulated miRNAs (7 in cornea tissue, 28 in iris tissue, 17 in lens tissue, 9 in retina tissue, 7 in RPE/choroid tissue, and 40 in sclera tissue) were observed. Overlapping expression changes in miRNAs were also found in different ocular components. Some of this miRNA dysregulation may be functionally involved in refractive myopia shift and axial length elongation.

  • Inducement and evaluation of a murine model of experimental myopia

    Jiang X., Kurihara T., Ikeda S., Kunimi H., Mori K., Torii H., Tsubota K.

    Journal of Visualized Experiments (Journal of Visualized Experiments)  2019 ( 143 )  2019.01

    ISSN  1940087X

     View Summary

    © 2019 Journal of Visualized Experiments. Murine model of myopia can be a powerful tool for myopia research because of the comparatively easy genetic manipulation. One way to induce myopia in animals is to put clear minus lenses in front of eyes for weeks (lens-induced myopia, LIM). However, extant protocols for inducement and evaluation vary from laboratory to laboratory. Here, we described a highly practical and reproducible method to induce LIM in mice using newly designed eyeglasses. The method fixes the lens stably in front of the mouse eye while allows the lens to be taken off for cleaning or topical drug administration. The phenotype is robust and efficient, and the variance is small. The method described here can be applied to mice right after weaning which extends the possible duration for experiments. We also gave technical advises for achieving reproducible results in refraction and axial length measurements. We hope the step-by-step protocol described here and the detailed article can help researchers perform myopia experiments with myopia more smoothly and make the data comparable across laboratories.

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Papers, etc., Registered in KOARA 【 Display / hide

Research Projects of Competitive Funds, etc. 【 Display / hide

  • Myopia development and scleral ER stress

    2020.04
    -
    2023.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, 池田 真一, Grant-in-Aid for Scientific Research (C), Principal Investigator

  • 骨格筋における免疫学的微小環境と筋機能

    2016.04
    -
    2019.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, 池田 真一, Grant-in-Aid for Scientific Research (B), Principal Investigator

  • 運動による筋の質・量の変化におけるマクロファージ中心仮説

    2013.04
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    2016.03

    科学研究費補助金, 池田真一, 基盤研究(C), Research grant, Principal Investigator

  • 運動によるインスリン感受性亢進における筋‐マクロファージ間コミュニケーション

    2011.04
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    2013.03

    科学研究費補助金, 池田真一, 若手研究(B), Research grant, Principal Investigator

  • 運動によるインスリン感受性亢進における筋ーマクロファージ間コミュニケーション

    2009.04
    -
    2011.03

    科学研究費補助金, 池田真一, 若手研究(B), Research grant, Principal Investigator