Evaluation of skeletal muscle fiber type using photothermal microscopy

• Project/Area Number: 17K19897
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Research Field: Health science and related fields
• Research Institution: The University of Electro-Communications
• Principal Investigator: Kano Yutaka 電気通信大学, 大学院情報理工学研究科, 教授 (90293133)
• Research Collaborator: KOBAYASHI Takayoshi ; NAKATA Kazuaki ; TANAKA Hiroki
• Project Period (FY): 2017-06-30 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥6,240,000 (Direct Cost: ¥4,800,000、Indirect Cost: ¥1,440,000); Fiscal Year 2018: ¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000); Fiscal Year 2017: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000)
• Keywords: 骨格筋 / 筋線維タイプ / ミトコンドリア / フォトサーマル顕微法 / 筋線維組成 / バイオイメージング

Outline of Final Research Achievements

Different fiber types of skeletal muscle (fast-twitch/slow-twitch) have different characteristics of mitochondrial distribution and its shape. Photothermal (PT) microscopes are imaged utilizing light absorbing molecules contained in tissue. In this study, we attempted to evaluate muscle fiber type from morphological characteristics of mitochondria using PT microscope. The PT imaging luminance values of SDH stained and unstained in slow muscle fibers were higher than those of fast muscle fibers. Slow muscle fibers showed many elongated mitochondrial shapes. On the other hand, the dotted mitochondrial shapes were seen in fast muscle fibers. These features were also confirmed in untreated muscle samples without muscle tissue fixation. Our original PT microscopic observation was shown to allow mitochondrial imaging in untreated muscle tissue samples.

Academic Significance and Societal Importance of the Research Achievements

骨格筋線維（筋細胞）は大きく速筋と遅筋に分類され，神経系や代謝的な特長が決定される．骨格筋研究において，筋線維タイプを分類することは基礎的な生体情報として重要である．これまで，筋線維タイプを生きたまま生体内で分類する方法は開発されていなかった．本研究はフォトサーマル（光熱変換）顕微法によって，線維タイプ別にミトコンドリア含有量や形態特性の違いを評価することに成功し，速筋と遅筋線維を生体内で同定することが可能であることを見いだした．

Research Products

• [Int'l Joint Research] カンザス州立大学(米国)
• [Journal Article] Muscle hypertrophy following blood flow-restricted low force isometric electrical stimulation in rat tibialis anterior: Role for muscle hypoxia. (2018)
  • Author(s): Nakajima T, Koide S, Yasuda T, Hasegawa T, Yamasoba T, Obi S, Toyoda S, Nakamura F, Inoue T, Poole DC, Kano Y
  • Journal Title: J Appl Physiol Volume: 印刷中 Issue: 1 Pages: 134-145
  • DOI: 10.1152/japplphysiol.00972.2017
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Microvascular Permeability of Skeletal Muscle After Eccentric Contraction-Induced Muscle Injury: In Vivo Imaging Using Two-Photon Laser Scanning Microscopy (2018)
  • Author(s): Kazuki Hotta, Bradley Behnke, Kazuto Masamoto, Rie Shimotsu, Naoya Onodera, Akihiko Yamaguchi, David Poole, Yutaka Kano
  • Journal Title: Journal of Applied Physiology Volume: 125 Issue: 2 Pages: 369-380
  • DOI: 10.1152/japplphysiol.00046.2018
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Photothermal imaging of skeletal muscle mitochondria (2017)
  • Author(s): Toru Tomimatsu, Jun Miyazaki, Yutaka Kano, and Takayoshi Kobayashi
  • Journal Title: Biomedical Optics Express Volume: 8 Issue: 6 Pages: 2965-2975
  • DOI: 10.1364/boe.8.002965
  • Peer Reviewed / Open Access
• [Presentation] フォトサーマル顕微鏡を用いた骨格筋細胞内のミトコンドリア形態観察 (2018)
  • Author(s): 田中宏樹，堀川大空，中田和明，小林孝嘉，狩野豊
  • Organizer: 2018日本体力医学会 学会大会
• [Remarks] 電気通信大学 基盤理工学専攻 狩野研究室
  • URL: http://www.ecc.es.uec.ac.jp/index.html