2023/12/01 更新

写真a

サカモト カズフミ
坂本 一史
所属
理工学術院 先進理工学部
職名
助手
学位
修士(理学) ( 2021年03月 早稲田大学 )

経歴

  • 2021年04月
    -
    継続中

    早稲田大学   理工学術院   助手

学歴

  • 2019年04月
    -
    継続中

    早稲田大学   先進理工学研究科   物理学及応用物理学専攻  

  • 2014年04月
    -
    2019年03月

    早稲田大学   先進理工学部   物理学科  

所属学協会

  • 2018年09月
    -
    継続中

    一般社団法人 日本生物物理学会

研究分野

  • 生物物理、化学物理、ソフトマターの物理 / 生物物理学

研究キーワード

  • 細胞集団の協同性

  • 細胞の空間配置

  • 同期現象

  • 伝播現象

  • 心筋細胞

 

論文

  • Importance of Spatial Arrangement of Cardiomyocyte Network for Precise and Stable On-Chip Predictive Cardiotoxicity Measurement

    Kazufumi Sakamoto, Suguru Matsumoto, Nanami Abe, Mitsuru Sentoku, Kenji Yasuda

    Micromachines   14 ( 4 ) 854 - 854  2023年04月  [査読有り]

    担当区分:筆頭著者

     概要を見る

    One of the advantages of human stem cell-derived cell-based preclinical screening is the reduction of the false negative/positive misjudgment of lead compounds for predicting their effectiveness and risks during the early stage of development. However, as the community effect of cells was neglected in the conventional single cell-based in vitro screening, the potential difference in results caused by the cell number and their spatial arrangement differences has not yet been sufficiently evaluated. Here, we have investigated the effect of the community size and spatial arrangement difference for cardiomyocyte network response against the proarrhythmic compounds from the viewpoint of in vitro cardiotoxicity. Using three different typical types of cell networks of cardiomyocytes, small cluster, large square sheet, and large closed-loop sheet were formed in shaped agarose microchambers fabricated on a multielectrode array chip simultaneously, and their responses were compared against the proarrhythmic compound, E-4031. The interspike intervals (ISIs) in large square sheets and closed-loop sheets were durable and maintained stable against E-4031 even at a high dose of 100 nM. In contrast, those in the small cluster, which fluctuated even without E-4031, acquired stable beating reflecting the antiarrhythmic efficacy of E-4031 from a 10 nM medium dose administration. The repolarization index, field potential duration (FPD), was prolonged in closed-loop sheets with 10 nM E-4031, even though small clusters and large sheets remained normal at this concentration. Moreover, FPDs of large sheets were the most durable against E-4031 among the three geometries of cardiomyocyte networks. The results showed the apparent spatial arrangement dependence on the stability of their interspike intervals, and FPD prolongation, indicating the importance of the geometry control of cell networks for representing the appropriate response of cardiomyocytes against the adequate amount of compounds for in vitro ion channel measurement.

    DOI

    Scopus

  • In Situ Agarose Microfabrication Technology Using Joule Heating of Micro Ionic Current for On-Chip Cell Network Analysis

    Kenji Shimoda, Haruki Watanabe, Yoshitsune Hondo, Mitsuru Sentoku, Kazufumi Sakamoto, Kenji Yasuda

    Micromachines   13 ( 2 ) 174 - 174  2022年01月  [査読有り]

     概要を見る

    Agarose microfabrication technology is one of the micropatterning techniques of cells having advantages of simple and flexible real-time fabrication of three-dimensional confinement microstructures even during cell cultivation. However, the conventional photothermal etching procedure of focused infrared laser on thin agarose layer has several limitations, such as the undesired sudden change of etched width caused by the local change of absorbance of the bottom surface of cultivation plate, especially on the indium-tin-oxide (ITO) wiring on the multi-electrode array (MEA) cultivation chip. To overcome these limitations, we have developed a new agarose etching method exploiting the Joule heating of focused micro ionic current at the tip of the micrometer-sized capillary tube. When 75 V, 1 kHz AC voltage was applied to the tapered microcapillary tube, in which 1 M sodium ion buffer was filled, the formed micro ionic current at the open end of the microcapillary tube melted the thin agarose layer and formed stable 5 μm width microstructures regardless the ITO wiring, and the width was controlled by the change of applied voltage squared. We also found the importance of the higher frequency of applied AC voltage to form the stable microstructures and also minimize the fluctuation of melted width. The results indicate that the focused micro ionic current can create stable local spot heating in the medium buffer as the Joule heating of local ionic current and can perform the same quality of microfabrication as the focused infrared laser absorption procedure with a simple set-up of the system and several advantages.

    DOI

    Scopus

    1
    被引用数
    (Scopus)
  • Stepwise neuronal network pattern formation in agarose gel during cultivation using non-destructive microneedle photothermal microfabrication

    Yuhei Tanaka, Haruki Watanabe, Kenji Shimoda, Kazufumi Sakamoto, Yoshitsune Hondo, Mitsuru Sentoku, Rikuto Sekine, Takahito Kikuchi, Kenji Yasuda

    Scientific Reports   11 ( 1 )  2021年12月  [査読有り]

     概要を見る

    Abstract

    Conventional neuronal network pattern formation techniques cannot control the arrangement of axons and dendrites because network structures must be fixed before neurite differentiation. To overcome this limitation, we developed a non-destructive stepwise microfabrication technique that can be used to alter microchannels within agarose to guide neurites during elongation. Micropatterns were formed in thin agarose layer coating of a cultivation dish using the tip of a 0.7 $$\upmu \mathrm{m}$$-diameter platinum-coated glass microneedle heated by a focused 1064-nm wavelength infrared laser, which has no absorbance of water. As the size of the heat source was 0.7 $$\upmu \mathrm{m}$$, which is smaller than the laser wavelength, the temperature fell to 45 $$^\circ \hbox {C}$$ within a distance of 7.0 $$\upmu \mathrm{m}$$ from the edge of the etched agarose microchannel. We exploited the fast temperature decay property to guide cell-to-cell connection during neuronal network cultivation. The first neurite of a hippocampal cell from a microchamber was guided to a microchannel leading to the target neuron with stepwise etching of the micrometer resolution microchannel in the agarose layer, and the elongated neurites were not damaged by the heat of etching. The results indicate the potential of this new technique for fully direction-controlled on-chip neuronal network studies.

    DOI PubMed

    Scopus

    5
    被引用数
    (Scopus)
  • Emergent synchronous beating behavior in spontaneous beating cardiomyocyte clusters

    Kazufumi Sakamoto, Yoshitsune Hondo, Naoki Takahashi, Yuhei Tanaka, Rikuto Sekine, Kenji Shimoda, Haruki Watanabe, Kenji Yasuda

    Scientific Reports   11 ( 1 )  2021年12月  [査読有り]

    担当区分:筆頭著者

     概要を見る

    Abstract

    We investigated the dominant rule determining synchronization of beating intervals of cardiomyocytes after the clustering of mouse primary and human embryonic-stem-cell (hES)-derived cardiomyocytes. Cardiomyocyte clusters were formed in concave agarose cultivation chambers and their beating intervals were compared with those of dispersed isolated single cells. Distribution analysis revealed that the clusters’ synchronized interbeat intervals (IBIs) were longer than the majority of those of isolated single cells, which is against the conventional faster firing regulation or “overdrive suppression.” IBI distribution of the isolated individual cardiomyocytes acquired from the beating clusters also confirmed that the clusters’ IBI was longer than those of the majority of constituent cardiomyocytes. In the complementary experiment in which cell clusters were connected together and then separated again, two cardiomyocyte clusters having different IBIs were attached and synchronized to the longer IBIs than those of the two clusters’ original IBIs, and recovered to shorter IBIs after their separation. This is not only against overdrive suppression but also mathematical synchronization models, such as the Kuramoto model, in which synchronized beating becomes intermediate between the two clusters’ IBIs. These results suggest that emergent slower synchronous beating occurred in homogeneous cardiomyocyte clusters as a community effect of spontaneously beating cells.

    DOI

    Scopus

    4
    被引用数
    (Scopus)
  • Geometric Understanding of Local Fluctuation Distribution of Conduction Time in Lined-Up Cardiomyocyte Network in Agarose-Microfabrication Multi-Electrode Measurement Assay

    Kazufumi Sakamoto, Shota Aoki, Yuhei Tanaka, Kenji Shimoda, Yoshitsune Hondo, Kenji Yasuda

    Micromachines   11 ( 12 ) 1105 - 1105  2020年12月  [査読有り]

    担当区分:筆頭著者

     概要を見る

    We examined characteristics of the propagation of conduction in width-controlled cardiomyocyte cell networks for understanding the contribution of the geometrical arrangement of cardiomyocytes for their local fluctuation distribution. We tracked a series of extracellular field potentials of linearly lined-up human embryonic stem (ES) cell-derived cardiomyocytes and mouse primary cardiomyocytes with 100 kHz sampling intervals of multi-electrodes signal acquisitions and an agarose microfabrication technology to localize the cardiomyocyte geometries in the lined-up cell networks with 100–300 μm wide agarose microstructures. Conduction time between two neighbor microelectrodes (300 μm) showed Gaussian distribution. However, the distributions maintained their form regardless of its propagation distances up to 1.5 mm, meaning propagation diffusion did not occur. In contrast, when Quinidine was applied, the propagation time distributions were increased as the faster firing regulation simulation predicted. The results indicate the “faster firing regulation” is not sufficient to explain the conservation of the propagation time distribution in cardiomyocyte networks but should be expanded with a kind of community effect of cell networks, such as the lower fluctuation regulation.

    DOI

    Scopus

    3
    被引用数
    (Scopus)

講演・口頭発表等

  • Loss of synchronous behavior in cardiomyocyte networks is independent of their spatial network patterns during hERG ion channel blocking

    Kazufumi Sakamoto, Kenji Yasuda

    第60回日本生物物理学会年会  

    発表年月: 2022年09月

  • Understanding the plasticity of beat synchronization by connecting and separating junctions between cardiomyocyte networks

    Suguru Matsumoto, Kazufumi Sakamoto, Kenji Yasuda

    第60回日本生物物理学会年会  

    発表年月: 2022年09月

  • Memorization of forced firing intervals in spontaneous beating cardiomyocyte networks

    Akira Nishizaki, Yoshitsune Hondo, Suguru Matsumoto, Kazufumi Sakamoto, Kenji Yasuda

    第60回日本生物物理学会年会  

    発表年月: 2022年09月

  • Can overdrive suppression explain the synchronized beating behavior of spontaneous beating cardiomyocyte clusters?

    Kazufumi Sakamoto, Yoshitsune Hondo, Kenji Yasuda

    第59回日本生物物理学会年会  

    発表年月: 2021年11月

  • Emergent slower synchronous beating behavior in spontaneous beating cardiomyocyte clusters

    Yoshitsune Hondo, Kazufumi Sakamoto, Kenji Yasuda

    第59回日本生物物理学会年会  

    発表年月: 2021年11月

  • Geometric understanding of local fluctuation distribution of conduction time in lined-up cardiomyocyte network in agarose-microfabrication multi-electrode measurement assay

    Kazufumi Sakamoto, Shota Aoki, Yuhei Tanaka, Kenji Shimoda, Yoshitsune Hondo, Kenji Yasuda

    1st International Conference on Micromachines and Applications  

    発表年月: 2021年04月

  • Fluctuation distribution of propagation time was conserved during excitation conduction in lined-up cardiomyocyte networks

    Kazufumi Sakamoto, Yoshitsune Hondo, Kenji Yasuda

    第58回日本生物物理学会年会  

    発表年月: 2020年09月

  • Observation of synchronized beating cycles of cardiomyocytes during three cell network formation in on-chip single cell measurement assay

    Yoshitsune Hondo, Kazufumi Sakamoto, Rikuto Sekine, Yuhei Tanaka, Haruki Watanabe, Kenji Shimoda, Kenji Yasuda

    第58回日本生物物理学会年会  

    発表年月: 2020年09月

  • Observation of direction-dependent asymmetrical propagation velocities in excitation conduction in a same cardiomyocyte networks on a chip

    Kazufumi Sakamoto, Shota Aoki, Yositsune Hondo, Masao Odaka, Akihiro Hattori, Kenji Yasuda

    第57回日本生物物理学会年会  

    発表年月: 2019年09月

  • Geometrical understanding of the local fluctuation in propagation of excitation conduction in cardiomyocyte network

    Shota Aoki, Kazufumi Sakamoto, Yositsune Hondo, Masao Odaka, Akihiro Hattori, Kenji Yasuda

    第57回日本生物物理学会年会  

    発表年月: 2019年09月

  • Development of a method to track conductions in cardiomyocyte network with a multi-electrode system

    Kaufumi Sakamoto, Natsuki Seki, Shota Aoki, Noki Takahashi, Masao Odaka, Kenji Matsuura, Akihiro Hattori, Kenji Yasuda

    第56回日本生物物理学会年会  

    発表年月: 2018年09月

  • Elucidation of community effect of cardiomyocyte by constructing cell cluster

    Noki Takahashi, Akihiro Yamashita, Kazufumi Sakamoto, Masao Odaka, Kenji Matsuura, Akihiro Hattori, Kenji Yasuda

    第56回日本生物物理学会年会  

    発表年月: 2018年09月

▼全件表示

共同研究・競争的資金等の研究課題

  • 心筋細胞の構成的集団形成によって顕在化する協同性の創発機構の解明

    日本学術振興会  科学研究費助成事業 基盤研究(C)

    研究期間:

    2023年04月
    -
    2026年03月
     

    坂本 一史

 

特定課題制度(学内資金)

  • 心筋細胞の構成的集団形成によって顕在化する協同性の創発機構の解明

    2022年  

     概要を見る

    本研究課題では、細胞が集団化することによって獲得される協同性が、集団の制御空間によってどのように異なるのかを明らかにするため、心筋細胞をモデルとして構成細胞の空間配置を制御したネットワーク同士の振る舞いの比較を行った。具体的には、ヒトES細胞由来の心筋細胞を用いて大きさと形状の異なる2次元心筋シートをチップ上に作成し、抗不整脈薬を投与した際のそれぞれの集団の細胞外電位を計測した結果から、拍動周期と細胞外電位持続時間の解析を行なった。結果は、見かけ上の細胞の空間配置によって集団の薬剤応答性が異なることを示しており、細胞ネットワークの形状制御によって構成細胞の性質が支配される可能性を示唆した。

  • 心筋細胞ネットワークの集団効果の理解

    2022年  

     概要を見る

    本研究課題では、細胞が集団化することによって獲得される協同性が、集団の制御空間によってどのように異なるのかを明らかにするため、心筋細胞をモデルとして構成細胞の空間配置を制御したネットワーク同士の振る舞いの比較を行った。具体的には、ヒトES細胞由来の心筋細胞を用いて大きさと形状の異なる2次元心筋シートをチップ上に作成し、抗不整脈薬を投与した際のそれぞれの集団の細胞外電位を計測した結果から、拍動周期と細胞外電位持続時間の解析を行なった。結果は、見かけ上の細胞の空間配置によって集団の薬剤応答性が異なることを示しており、細胞ネットワークの形状制御によって構成細胞の性質が支配される可能性を示唆した。

  • 心筋細胞ネットワークの集団効果の理解

    2021年  

     概要を見る

    従来、心筋細胞の同期則に関しては、興奮伝導の観点から最も拍動の速い細胞が集団を支配するという概念が一般に信じられている。これを検証するため、自律拍動する心筋細胞を構成的に集団化させ、その同期化現象について細胞同士の結合前後で拍動周期の比較解析を行なった。結果は、同期後の集団の拍動は、従来の考えである「より速い拍動をする細胞」に追従しないだけでなく、集団を構成するどの心筋細胞の自律拍動よりも遅い周期で拍動することを見出した。我々の発見は、「集団化」は単なる細胞の加算・相加平均ではなく、新たな「集団」固有の法則性・状態を創発する機構であるという考え方を持つ必要性を示唆している。