Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Polymer Journal  

Cell adhesion on biomaterial surfaces has been extensively studied from the perspective of the adsorption properties of adhesive ligands, while recent research on mechanobiology has been revealing a critical role of the mechanical properties of the extracellular milieu in the control of cell adhesion, such as the stiffness and viscoelasticity of the matrix. Although the effects of the lateral mobility of an adhesive ligand have been intensively investigated in a model substrate with water-soluble polymer layers, less is known about those in the setting of lateral deformability of hydrophobic condensed polymer layers. In this study, to help clarify this issue, we used PNIPAAm-grafted substrates with a well-controlled degree of graft-polymerization (DGP) as a typical hydrophobic condensed polymer surface at a cell culture temperature of 37 degrees C. We observed a clear negative correlation between cell spreading and DGP of PNIPAAm regardless of the amount of fibronectin adsorbed on the substrates, which was found to be attributable to the lateral deformability of a condensed PNIPAAm layer based on lateral force microscopic analysis. The surface-lateral-deformation-induced modulation in stability and maturation of focal adhesion of the cells is discussed in relation to the matrix-strain-induced alteration of the density distribution of adsorbed adhesive ligands.

DOI： 10.1038/s41428-021-00577-w

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Language：English   Publishing type：Research paper (scientific journal)  

Stiffness-gradient-induced cellular taxis, so-called durotaxis, has been extensively studied on a substrate with a single broad or steep stiffness gradient. However, in actual living tissues, cells should sense cell-scaled heterogeneous elasticity distribution in the extracellular matrix. In this study, to clarify the effect of the cell-scale heterogeneity of matrix-elasticity on durotaxis, we examined the motility of different types of cells on microelastically-striped patterned gels with different cell-sized widths. We found that cells accumulated in stiff regions with specific width on cell-type-dependency, even when a stiffness gradient is too small to induce usual durotaxis with a monotonic stiffness gradient. Fibroblast cells accumulated in a wide stiff region of multicellular size, while mesenchymal stem cells localized in a narrow stiff region of single-cell size. It was revealed that durotactic activity is critically affected not only with the cell type but also with the cell-scale heterogeneity of matrix-elasticity. Based on the shape-fluctuation-based analysis of cell migration, the dynamics of the pseudopodia were found to play a key role in determining the behaviors of general durotaxis. Our results suggest that design of cell-scale heterogeneity of matrix-elasticity is pivotal in controlling directional cell migration, the spontaneous cell-patterning, and development of the tissue on the biomaterials surfaces.

DOI： 10.1016/j.biomaterials.2019.119647

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Pericytes (PCs) wrap around endothelial cells (ECs) and perform diverse functions in physiological and pathological processes. Although molecular interactions between ECs and PCs have been extensively studied, the morphological processes at the cellular level and their underlying mechanisms have remained elusive. In this study, using a simple cellular Potts model, we explored the mechanisms for EC wrapping by PCs. Based on the observed in vitro cell wrapping in three-dimensional PC-EC coculture, the model identified four putative contributing factors: preferential adhesion of PCs to the extracellular matrix (ECM), strong cell-cell adhesion, PC surface softness and larger PC size. While cell-cell adhesion can contribute to the prevention of cell segregation and the degree of cell wrapping, it cannot determine the orientation of cell wrapping alone. While atomic force microscopy revealed that PCs have a larger Young's modulus than ECs, the experimental analyses supported preferential ECM adhesion and size asymmetry. We also formulated the corresponding energy minimization problem and numerically solved this problem for specific cases. These results give biological insights into the role of PC-ECM adhesion in PC coverage. The modelling framework presented here should also be applicable to other cell wrapping phenomena observed in vivo.

DOI： 10.1098/rsif.2019.0739

Language：English   Publishing type：Research paper (scientific journal)  

Abstract: It is still difficult to precisely control microscopic wrinkles on the surface of functional materials, especially biomimetic soft hydrogels with an elastic modulus lower than 100 kPa. This is due to the difficulty in realizing the systematic and independent regulation of elasticity on the top surface and in the bulk of hydrogels, which is essential for the generation of surface microwrinkles. To overcome this problem, using a two-step photocrosslinking process with VIS and UV irradiation of a photocurable gelatinous sol, we developed a method for independently regulating the elastic modulus on the surface and in the bulk to obtain wrinkles on a biomimetic soft gel. Photocurable gelatin was first irradiated and crosslinked with VIS light in the presence of the water-soluble radical generator sulfonyl camphorquinone, which is effective in forming thick bulk gels. Next, the top surface of these precrosslinked gels was irradiated with UV light in the presence of surface-coated water-insoluble camphorquinone. As a result, this two-step photocrosslinking process enabled to independently control the elastic moduli of the surface and the bulk lower than 100 kPa and to generate several-micron-scale wrinkles on the soft hydrogel surface.

DOI： 10.1038/s41428-019-0299-8

Language：English   Publishing type：Research paper (scientific journal)  

The mechanics and architectures of the extracellular matrix (ECM) critically influence 3D cell migration processes, such as cancer cell invasion and metastasis. Understanding the roles of mechanical and structural factors in the ECM could provide an essential basis for cancer treatment. However, it is generally difficult to independently characterize these roles due to the coupled changes in these factors in conventional ECM model systems. In this study, to solve this problem, we developed elasticity/porosity-tunable electrospun fibrous gel matrices composed of photocrosslinked gelatinous microfibers (nanometer-scale-crosslinked chemical gels) with well-regulated bonding (tens-of-micron-scale fiber-bonded gels). This system enables independent modulation of microscopic fiber elasticity and matrix porosity, i.e., the mechanical and structural conditions of the ECM. The elasticity of fibers was tuned with photocrosslinking conditions. The porosity was regulated by changing the degree of interfiber bonding. The influences of these factors of the fibrous gel matrix on the motility of MDA-MB-231 tumorigenic cells and MCF-10A nontumorigenic cells were quantitatively investigated. MDA-MB-231 cells showed the highest degree of MMP-independent invasion into the matrix composed of fibers with a Young’s modulus of 20 kPa and a low degree of interfiber bonding, while MCF-10A cells did not show invasive behavior under the same matrix conditions.

DOI： 10.1038/s41428-019-0283-3

Language：English   Publishing type：Research paper (scientific journal)  

Mesenchymal stem cells (MSCs) are one of the most useful cell resources for clinical application in regenerative medicine. However, standardization and quality assurance of MSCs are still essential problems because the stemness of MSCs depends on such factors as the collection method, individual differences associated with the source, and cell culture history. As such, the establishment of culture techniques which assure the stemness of MSCs is of vital importance. One important factor affecting MSCs during culture is the effect of the mechanobiological memory of cultured MSCs built up by their encounter with particular mechanical properties of the extracellular mechanical milieu. How can we guarantee that MSCs will remain in an undifferentiated state? Procedures capable of eliminating effects related to the history of the mechanical dose for cultured MSCs are required. For this problem, we have tried to establish the design of microelastically patterned cell-culture matrix which can effectively induce mechanical oscillations during the period of nomadic migration of cells among different regions of the matrix. We have previously observed before that the MSCs exposed to such a growth regimen during nomadic culture keep their undifferentiated state—with this maintenance of stemness believed due to lack of a particular regular mechanical dosage that is likely to determine a specific lineage. We have termed this situation as “frustrated differentiation”. In this minireview, I introduce the concept of frustrated differentiation of MSCs and show possibility of purposeful regulation of this phenomenon.

DOI： 10.1007/s12551-019-00528-z

Repository Public URL： https://hdl.handle.net/2324/7174491

Language：English   Publishing type：Research paper (scientific journal)  

The mechanical properties of the extracellular microenvironment, including its stiffness, play a crucial role in stem cell fate determination. Although previous studies have demonstrated that the developing brain exhibits spatiotemporal diversity in stiffness, it remains unclear how stiffness regulates stem cell fate towards specific neural lineages. Here, we established a culture substrate that reproduces the stiffness of brain tissue using tilapia collagen for in vitro reconstitution assays. By adding crosslinkers, we obtained gels that are similar in stiffness to living brain tissue (150–1500 Pa). We further examined the capability of the gels serving as a substrate for stem cell culture and the effect of stiffness on neural lineage differentiation using human iPS cells. Surprisingly, exposure to gels with a stiffness of approximately 1500 Pa during the early period of neural induction promoted the production of dorsal cortical neurons. These findings suggest that brain-stiffness-mimicking gel has the potential to determine the terminal neural subtype. Taken together, the crosslinked tilapia collagen gel is expected to be useful in various reconstitution assays that can be used to explore the role of stiffness in neurogenesis and neural functions. The enhanced production of dorsal cortical neurons may also provide considerable advantages for neural regenerative applications.

DOI： 10.1038/s41598-018-38395-5

Language：English   Publishing type：Research paper (scientific journal)  

Even though microgels are used in a wide variety of applications, determining their mechanical properties has been elusive because of the difficulties in analysis. In this study, we investigated the surface elasticity of a spherical microgel of gelatin prepared inside a lipid droplet by using micropipet aspiration. We found that gelation inside a microdroplet covered with lipid membranes increased Young's modulus E toward a plateau value E∗ along with a decrease in gel size. In the case of 5.0 wt % gelatin gelled inside a microsized lipid space, the E∗ for small microgels with R ≤ 50 μm was 10-fold higher (35-39 kPa) than that for the bulk gel (∼3 kPa). Structural analysis using circular dichroism spectroscopy and a fluorescence indicator for ordered beta sheets demonstrated that the smaller microgels contained more beta sheets in the structure than the bulk gel. Our finding indicates that the confinement size of gelling polymers becomes a factor in the variation of elasticity of protein-based microgels via secondary structure changes.

DOI： 10.1021/acscentsci.7b00625

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Directional cell movement from a softer to a stiffer region on a culture substrate with a stiffness gradient, so-called durotaxis, has attracted considerable interest in the field of mechanobiology. Although the strength of a stiffness gradient has been known to influence durotaxis, the precise manipulation of durotactic cells has not been established due to the limited knowledge available on how the threshold stiffness gradient (TG) for durotaxis is determined. In the present study, to clarify the principles for the manipulation of durotaxis, we focused on the absolute stiffness of the soft region and evaluated its effect on the determination of TG required to induce durotaxis. Microelastically patterned gels that differed with respect to both the absolute stiffness of the soft region and the strength of the stiffness gradient were photolithographically prepared using photo-cross-linkable gelatins, and the TG for mesenchymal stem cells (MSCs) was examined systematically for each stiffness value of the soft region. As a result, the TG values for soft regions with stiffnesses of 2.5, 5, and 10 kPa were 0.14, 1.0, and 1.4 kPa/μm, respectively, i.e., TG markedly increased with an increase in the absolute stiffness of the soft region. An analysis of the area and long-axis length for focal adhesions revealed that the adhesivity of MSCs was more stable on a stiffer soft region. These results suggested that the initial location of cells starting durotaxis plays an essential role in determining the TG values and furthermore that the relationship between the position-dependent TG and intrinsic stiffness gradient (IG) of the culture substrate should be carefully reconsidered for inducing durotaxis; IG must be higher than TG (IG ≥ TG). This principle provides a fundamental guide for designing biomaterials to manipulate cellular durotaxis.

DOI： 10.1021/acs.langmuir.8b02529

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DOI： DOI: 10.1002/admi.201601125

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DOI： DOI: 10.1021/acsami.6b07614

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DOI： DOI 10.1007/978-1-4939-3584-0_25

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Language：English   Publishing type：Research paper (scientific journal)  

Repository Public URL： https://hdl.handle.net/2324/7177954

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細胞は弾性基材表面の硬い領域を指向して運動する性質を示す（メカノタクシス）ことが知られていたが、その駆動のための表面弾性勾配の定量的条件は確立されておらず、メカノタクシスを系統的に誘導し制御することは不可能であった。本論文ではこの問題に対して、独自の弾性率可変ヒドロゲルのマイクロ弾性パターニング技術を確立することにより、細胞のメカノタクシスの誘導条件を初めて明確にした。その技術は細胞運動を操作する培養基材設計の一般的な基礎となるものである。

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DOI： 10.1016/j.biomaterials.2004.01.063

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DOI： 10.1021/bm0502617

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DOI： 10.1002/jbm.b.30336

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DOI： 10.1002/jbm.a.30260

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DOI： 10.1016/j.biomaterials.2004.10.007

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DOI： 10.1016/j.biomaterials.2004.08.006

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DOI： 10.1002/jbm.a.20012

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DOI： 10.1021/bm034231k

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DOI： 10.1016/S0142-9612(03)00344-2

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DOI： 10.1562/0031-8655(2003)077<0480:POCAAP>2.0.CO;2

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DOI： 10.1063/1.1475759

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DOI： 10.1021/ja000230d

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Language：English   Publisher：Histochemistry and Cell Biology  

Förster resonance energy transfer (FRET) serves as a tool for measuring protein–protein interactions using various sensor molecules. The tension sensor module relies on FRET technology. In our study, this module was inserted within the actinin molecule to measure the surface tension of the cells. Given that the decay curve of FRET efficiency correlates with surface tension increase, precise and accurate efficiency measurement becomes crucial. Among the methods of FRET measurements, FRET efficiency remains the most accurate if sample fixation is successful. However, when cells were fixed with 4% paraformaldehyde (PFA), the actinin-FRET sensor diffused across the cytoplasm; this prompted us to explore fixation method enhancements. Glyoxal fixative has been reported to improve cytoskeletal morphologies compared to PFA. However, it was not known whether glyoxal fits FRET measurements. Glyoxal necessitates an acetic acid solution for fixation; however, acidic conditions could compromise fluorescence stability. We observed that the pH working range of glyoxal fixative aligns closely with MES (methyl-ethylene sulfonic acid) Good’s buffer. Initially, we switched the acidic solution for MES buffer and optimized the fixation procedure for in vitro and in vivo FRET imaging. By comparing FRET measurements on hydrogels with known stiffness to tumor nodules in mouse lung, we estimated in vivo stiffness. The estimated stiffness of cancerous tissue was harder than the reported stiffness of smooth muscle. This discovery shed lights on how cancer cells perceive environmental stiffness during metastasis.

DOI： 10.1007/s00418-024-02304-x

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Language：English   Publisher：Colloids and Surfaces B: Biointerfaces  

A plasmonic metasurface composed of a self-assembled monolayer of gold nanoparticles allows for fluorescence imaging with high spatial resolution, owing to the collective excitation of localized surface plasmon resonance. Taking advantage of fluorescence imaging confined to the nano-interface, we examined actin organization in breast cancer cell lines with different metastatic potentials during cell adhesion. Live-cell fluorescence imaging confined within tens of nanometers from the substrate shows a high actin density spanning < 1 μm from the cell edge. Live-cell imaging revealed that the breast cancer cell lines exhibited different actin patterns during the initial phase of cell adhesion (∼ 1 h). Non-tumorous MCF10A cells exhibited symmetric actin localization at the cell edge, whereas highly metastatic MDA-MB-231 cells showed asymmetric actin localization, demonstrating rapid polarization of MDA-MB-231 cells upon adhesion. The rapid actin organization observed by our plasmonic metasurface-based fluorescence imaging provides information on how quickly cancer cells sense the underlying substrate.

DOI： 10.1016/j.colsurfb.2024.113876

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Language：Japanese   Publisher：Japanese Society for Medical and Biological Engineering  

<p>幹細胞の周囲力学場の感受とメカノトランスダクション応答は、運動特性や分化特性、さまざまな生理活性分子の分泌特性の調節に深く関わるため、幹細胞を組織工学応用する際にはその培養環境力学場の系統的設計技術の拡充は本質的課題の一つである。我々はこれまでに間葉系幹細胞やiPS細胞に対して、これらの機能を強化もしくは最適制御する培養力学場の粘弾性の空間分布設計に取り組んできた。前者MSCに対しては、再生医療細胞医薬品としての応用に必須となる未分化保持および治療有効性因子の分泌性能の強化を可能とする環境力学場の設計原理の開拓を進め、治療有効性増強した幹細胞の識別を可能とする簡便な評価指標を開発した。後者iPS細胞に関しては、オルガノイドの再現性高く効率的な誘導を可能とする粘弾性マトリックスの設計指針を見出し、マトリゲル代替材料のプロトタイプを開発した。本発表では、これらの成果について紹介し、再生医療・組織構築に資する幹細胞操作マトリックスの設計例について議論する。</p>

DOI： 10.11239/jsmbe.annual62.97_1

CiNii Research

Language：Japanese   Publisher：The Biophysical Society of Japan General Incorporated Association  

DOI： 10.2142/biophys.64.177

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：iScience  

Contractile force generated in actomyosin stress fibers (SFs) is transmitted along SFs to the extracellular matrix (ECM), which contributes to cell migration and sensing of ECM rigidity. In this study, we show that efficient force transmission along SFs relies on actin crosslinking by α-actinin. Upon reduction of α-actinin-mediated crosslinks, the myosin II activity induced flows of actin filaments and myosin II along SFs, leading to a decrease in traction force exertion to ECM. The fluidized SFs maintained their cable integrity probably through enhanced actin polymerization throughout SFs. A computational modeling analysis suggested that lowering the density of actin crosslinks caused viscous slippage of actin filaments in SFs and, thereby, dissipated myosin-generated force transmitting along SFs. As a cellular scale outcome, α-actinin depletion attenuated the ECM-rigidity-dependent difference in cell migration speed, which suggested that α-actinin-modulated SF mechanics is involved in the cellular response to ECM rigidity.

DOI： 10.1016/j.isci.2023.106090

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Language：English   Publisher：(公社)日本分析化学会  

細胞接着界面における局所pH分布を可視化するため、pH応答性蛍光色素フルオレセインイソチオシアナート(FITC)で化学修飾したガラス基板を調製し、線維芽細胞(NIH/3T3)と癌細胞(HeLa)の接着界面におけるFITC蛍光強度の分布を観察し、FITC画像を観察した接着斑の分布と比較した。FITC画像を種々のpH培地で事前測定した表面固定化FITCのpH-蛍光校正データに基づいてpHマッピングに変換すると、HeLa細胞の厚い内周では細胞外側(pH7.4)よりpHが低下(6.8～7.0pH)している著しく大きな領域を認めたが、3T3細胞では薄い外周で小規模のpH低下領域を認めた。低下pH領域では多くの接着斑が重なり、画像解析ではインテグリン接着リガンド結合蓄積によるグリコカリックス圧縮促進を反映して、大きな接着斑が内部に低pH部を持つ傾向を認めた。この傾向は3T3細胞よりHeLaの方が強かった。

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Cell-substrate adhesion nano-interfaces can, in principle, exhibit a spatial distribution of local pH values under the influence of the weakly acidic microenvironment of glycocalyx grafted on lipid bilayer cell membrane which is compressed and closely attached to culture substrate in the vicinity of integrin-adhesion complexes. However, a simple local pH distribution imaging methodology has not been developed. In this study, to visualize the local pH distribution at the cell adhesion interface, we prepared glass substrates chemically modified with a pH-responsive fluorescent dye fluorescein isothiocyanate (FITC), observed the distribution of FITC fluorescence intensity at the adhesion interface of fibroblast (NIH/3T3) and cancer cells (HeLa), and compared the FITC images with the observed distribution of focal adhesions. FITC images were converted to pH mapping based on the pH-fluorescence calibration data of surface-immobilized FITC pre-measured in different pH media, which showed significantly larger regions with lowered pH level (6.8–7.0) from outside the cell (pH 7.4) were observed at the thick inner periphery of HeLa cells while 3T3 cells exhibited smaller lowered pH regions at the thin periphery. The lowered pH regions overlapped with many focal adhesions, and image analysis showed that larger focal adhesions tend to possess more lowered pH sites inside, reflecting enhanced glycocalyx compression due to accumulated integrin-adhesion ligand binding. This tendency was stronger for HeLa than for 3T3 cells. The role of glycocalyx compression and the pH reduction at the cell adhesive interface is discussed. Graphical abstract: [Figure not available: see fulltext.]

DOI： 10.1007/s44211-022-00239-8

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Other Link： https://link.springer.com/article/10.1007/s44211-022-00239-8/fulltext.html

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>Cell adhesion control is a crucial challenge in the design of biomaterials to achieve specific cellular functions and applications. For instance, when implanting artificial organs into the human body, suppressing undesirable cell adhesion becomes essential to avoid adverse biological responses such as blood coagulation and thrombosis. On the other hand, for tissue reconstruction using cell scaffolding materials, ensuring appropriate cell adhesion to the material surface is required. Particularly, cell adhesion morphology is closely associated with cellular processes, including proliferation, differentiation, and orderly structural formation, making versatile control of cell adhesion indispensable in tissue engineering. Cell-substrate adhesion progresses through the binding of cell surface proteins, known as integrins, to adhesion ligands on the material surface. Therefore, the degree of cell adhesion can be manipulated by modulating the presentation of adhesion ligand quantity and its spatial density on the material surface. Traditional material design has focused on modifying adhesion ligand chemistry and physical adsorption characteristics. Additionally, numerous reports have highlighted the significance of material surface mechanics as essential variables in cell adhesion control. As cells exert traction forces on the adhesive substrate, the deformable substrate causes simultaneous movement of integrin-ligand pairs. Consequently, the deformation characteristics of the adhesion interface significantly influence the spatial distribution of adhesion ligands and the binding stability to integrins, representing vital design elements.</p>

DOI： 10.1299/jsmemecj.2023.f021-3

CiNii Research

Language：English   Publisher：The Biophysical Society of Japan  

<p>Mesenchymal stem cells (MSCs) have the potential for self-renewal and multipotency to differentiate into various lineages. Thus, they are of great interest in regenerative medicine as a cell source for tissue engineering. Substrate stiffness is one of the most extensively studied exogenous physical factors; however, consistent results have not always been reported for controlling MSCs. Conventionally used stiff culture substrates, such as tissue-culture polystyrene and glass, enhance nuclear localization of a mechanotransducer YAP and a pre-osteogenic transcription factor RUNX2, and bias MSCs towards the osteogenic lineage, even without osteogenic-inducing soluble factors. The mechanosensitive nature and intrinsic heterogeneity present challenges for obtaining reproducible results. This review summarizes the heterogeneity in human MSC response, specifically, nuclear/cytoplasmic localization changes in the mechanotransducer yes-associated protein (YAP) and the osteogenic transcription factor RUNX2, in response to substrate stiffness. In addition, a perspective on the intracellular factors attributed to response heterogeneity is discussed. The optimal range of stiffness parameters, Young’s modulus, for MSC expansion culture to suppress osteogenic differentiation bias through the suppression of YAP and RUNX2 nuclear localization, and cell cycle progression is likely to be surprisingly narrow for a cell population from an identical donor and vary among cell populations from different donors. We believe that characterization of the heterogeneity of MSCs and understanding their biological meaning is an exciting research direction to establish guidelines for the design of culture substrates for the sophisticated control of MSC properties.</p>

DOI： 10.2142/biophysico.bppb-v20.0018

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Language：English   Publisher：The Japan Society of Mechanical Engineers  

<p>Cell adhesion to the extracellular matrix critically influences essential cellular functions such as proliferation, motility, and differentiation, all of which are crucial for maintaining tissue homeostasis. Achieving precise control over cell adhesion to artificial substrates is a pivotal challenge in biomaterials engineering. This minireview aims to elucidate the multifaceted considerations for substrate surface design, grounded in the detailed molecular mechanisms of the cell adhesion complex. We systematically outline key design variables for controlling cell adhesion, such as the spatial arrangement of adhesion ligands, matrix stiffness, and surface lateral deformation. The review also delves into the emerging role of mechanobiology of membrane glycocalyx, with a particular focus on the impact on the formation of focal adhesion complexes. Collectively, these considerations offer a methodology for fine-tuned control of cell adhesion and its subsequent cellular functions on engineered biomaterials.</p>

DOI： 10.1299/jbse.23-00358

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Language：English   Publisher：Japan Society for Cell Biology  

Abstract Cellular durotaxis has been extensively studied in the field of mechanobiology. In principle, asymmetric mechanical field of a stiffness gradient generates motile polarity in a cell, which is a driving factor of durotaxis. However, the actual process by which the motile polarity in durotaxis develops is still unclear. In this study, to clarify the details of the kinetics of the development of durotactic polarity, we investigated the dynamics of both cell-shaping and the microscopic turnover of focal adhesions (FAs) for Venus-paxillin-expressing fibroblasts just crossing an elasticity boundary prepared on microelastically patterned gels. The Fourier mode analysis of cell-shaping based on a persistent random deformation model revealed that motile polarity at a cell-body scale was established within the first few hours after the leading edges of a moving cell passed through the boundary from the soft to the stiff regions. A fluorescence recovery after photobleaching (FRAP) analysis showed that the mobile fractions of paxillin at FAs in the anterior part of the cells exhibited an asymmetric increase within several tens of minutes after cells entered the stiff region. The results demonstrated that motile polarity in durotactic cells is established through the hierarchical step-wise development of different types of asymmetricity in the kinetics of FAs activity and cell-shaping with a several-hour time lag.

CiNii Research

Publisher：Advanced NanoBiomed Research  

A plasmonic metasurface composed of self-assembled gold nanoparticles enables high-speed interfacial imaging with high axial and lateral resolution down to the theoretical limit under a widefield microscope. This high-spatiotemporal resolution imaging method monitors “early molecular events” in the adhesion of 3T3 fibroblasts expressing Venus-paxillin and LifeAct-mScarlet, revealing unique transient cell dynamics. Upon attaching to the SiO2-coated plasmonic metasurface, cells exhibit fibrous nascent adhesions spreading radially at the periphery, together with actively moving membrane blebs. These fibrous nascent structures exist transiently during passive spreading and disappear upon transition to active spreading with mature focal adhesions (FAs). The structure forms on a poor-cell-adhesive SiO2-coated surface but not on a fibronectin-preadsorbed cell-adhesive surface, suggesting that it temporarily anchors cells to the interface but maintains freedom before active cell spreading. These momentary molecular-level phenomena at the nanointerface are successfully captured by the herein described high-spatiotemporal resolution live-cell imaging method using a plasmonic metasurface.

DOI： 10.1002/anbr.202100100

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CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Biophysical Society of Japan  

<p>In living tissues where cells migrate, the spatial distribution of mechanical properties, especially matrix stiffness, is generally heterogeneous, with cell scales ranging from 10 to 1000 μm. Since cell migration in the body plays a critical role in morphogenesis, wound healing, and cancer metastasis, it is essential to understand the migratory dynamics on the matrix with cell-scale stiffness heterogeneity. In general, cell migration is driven by the extension and contraction of the cell body owing to the force from actin polymerization and myosin motors in the actomyosin cytoskeleton. When a cell is placed on a matrix with a simple stiffness gradient, directional migration called durotaxis emerges because of the asymmetric extension and contraction of the pseudopodia, which is accompanied by the asymmetric distribution of focal adhesions. Similarly, to determine cell migration on a matrix with cell-scale stiffness heterogeneity, the interaction between cell-scale stiffness heterogeneity and cellular responses, such as the dynamics of the cell-matrix adhesion site, intracellular prestress, and cell shape, should play a key role. In this review, we summarize systematic studies on the dynamics of cell migration, shaping, and traction force on a matrix with cell-scale stiffness heterogeneity using micro-elastically patterned hydrogels. We also outline the cell migration model based on cell-shaping dynamics that explains the general durotaxis induced by cell-scale stiffness heterogeneity. This review article is an extended version of the Japanese article, Dynamics of Cell Shaping and Migration on the Matrix with Cell-scale Stiffness-heterogeneity, published in SEIBUTSU BUTSURI Vol. 61, p. 152–156 (2021).</p>

DOI： 10.2142/biophysico.bppb-v19.0036

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CiNii Research

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Language：English   Publishing type：Research paper (scientific journal)  

In a previous study (Sakai A., et al., ACS Cent. Sci., 4, 477 (2018)), a spherical microgel of gelatin prepared inside a lipid droplet was reported to have a higher surface elasticity than the bulk gel. In this study, we investigate the role of contact or lack of contact between gelatin and the lipid membrane as well as the micrometric confinement to isolate the dominant cause of this higher elasticity of microgels. For our experiment, we prepared a concave microgel of gelatin with two surfaces, with one surface in contact with the lipid membrane and the other without being in contact with the membrane. Next, we measured the elasticities of both the surfaces by using micropipette aspiration. Although the elasticity of the surface not in contact with the lipid membrane was slightly lower than that of the surface in contact with the membrane, the elasticity value was much higher than that for the bulk gel. Further, it was found that the droplet confinement without lipids did not decrease the elasticity of gelatin microgels. These results demonstrate that the dominant factor responsible for the higher elasticity of gelatin microgels is micrometric confinement and not their contact with the lipid membrane.

DOI： 10.1678/rheology.47.55

Language：English   Publishing type：Research paper (scientific journal)  

This paper proposes a simple, effective, non-scanning method for the visualization of a cell-attached nanointerface. The method uses localized surface plasmon resonance (LSPR) excited homogeneously on a two-dimensional (2D) self-assembled gold-nanoparticle sheet. The LSPR of the gold-nanoparticle sheet provides high-contrast interfacial images due to the confined light within a region a few tens of nanometers from the particles and the enhancement of fluorescence. Test experiments on rat basophilic leukemia (RBL-2H3) cells with fluorescence-labeled actin filaments revealed high axial and lateral resolution even under a regular epifluorescence microscope, which produced higher quality images than those captured under a total internal reflection fluorescence (TIRF) microscope. This non-scanning-type, high-resolution imaging method will be an effective tool for monitoring interfacial phenomena that exhibit relatively rapid reaction kinetics in various cellular and molecular dynamics.

DOI： 10.1038/s41598-017-04000-4

Language：English  

DOI： 10.1016/j.bpj.2016.11.2328

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.biomaterials.2013.06.011

Language：English   Publishing type：Research paper (scientific journal)  

To control cell motility is one of the essential technologies for biomedical engineering. To establish a methodology of the surface design of elastic substrate to control the long-range cell movements, here we report a sophisticated cell culture hydrogel with a micro-elastically patterned surface that allows long-range durotaxis. This hydrogel has a sawlike pattern with asymmetric gradient ratchet teeth, and rectifies random cell movements. Durotaxis only occurs at boundaries in which the gradient strength of elasticity is above a threshold level. Consequently, in gels with unit teeth patterns, durotaxis should only occur at the sides of the teeth in which the gradient strength of elasticity is above this threshold level. Therefore, such gels are expected to support the long-range biased movement of cells via a mechanism similar to the Feynman-Smoluchowski ratchet, i.e., rectified cell migration. The present study verifies this working hypothesis by using photolithographic microelasticity patterning of photocurable gelatin gels. Gels in which each teeth unit was 100-120 mu m wide with a ratio of ascending: descending elasticity gradient of 1: 2 and a peak elasticity of ca. 100 kPa supported the efficient rectified migration of 3T3 fibroblast cells. In addition, long-range cell migration was most efficient when soft lanes were introduced perpendicular to the saw-like patterns. This study demonstrates that asymmetric elasticity gradient patterning of cell culture gels is a versatile means of manipulating cell motility.

DOI： 10.1371/journal.pone.0078067

Language：English   Publishing type：Research paper (scientific journal)  

Localized and sustained delivery of the therapeutic genes using a solid carrier matrix is a potential approach to develop highly curative treatments. Electrospun nanofiber mesh of biodegradable polymer has been applied extensively as a carrier for localized and sustained delivery of drugs, proteins, and DNA, but it remains difficult to release sufficient amounts of DNA while maintaining structural and functional integrity. To realize the stable sustained release of the healthy plasmid DNA (pDNA) from electrospun fiber mesh, a novel method was examined for loading pDNA into the fibers based on solid-in-oil (S/O) nanodispersion of pDNA in organic solvent for electrospinning polymer solution: S/O nanodispersion electrospinning. A prepared pDNA-loaded fiber mesh made of biodegradable polymer showed sustained release of pDNA without burst release. From luciferase activity-based in vitro transcriptiontranslation assay, pDNA released from meshes of the S/O nanodispersion retained about 60% luciferase activity of control pDNA, whereas pDNA released from the meshes of simple mixing showed only about 5% activity, indicating that S/O nanodispersion electrospinning is effective for loading pDNA into electrospun fiber meshes while maintaining their healthy functions. Effectiveness of S/O nanodispersion electrospinning was verified for fabricating a sustained release carrier matrix for high molecular weight bioactives, including therapeutic genes.

DOI： 10.1080/09205063.2012.755600

Language：English   Publishing type：Research paper (scientific journal)  

We have quantitatively determined how the morphology and adhesion strength of myoblast cells can be regulated by photocurable gelatin gels, whose mechanical properties can be fine-tuned by a factor of 10(3) (0.1 kPa <= E <= 140 kPa). The use of such gels allows for the investigation of mechanosensing of cells not only near the natural mechanical microenvironments (E similar to 10 kPa) but also far below and beyond of the natural condition. Optical microscopy and statistical image analysis revealed that myoblast cells sensitively adopt their morphology in response to the substrate elasticity at E similar to 1-20 kPa, which can be characterized by the significant changes in the contact area and order parameters of actin cytoskeletons. In contrast, the cells in contact with the gels with lower elastic moduli remained almost round, and the increase in the elasticity beyond E similar to 20 kPa caused no distinct change in morphology. In addition to the morphological analysis, the adhesion strength was quantitatively evaluated by measuring the critical detachment pressure with an aid of intensive pressure waves induced by picosecond laser pulses. This noninvasive technique utilizing extremely short pressure waves (pulse time width similar to 100 ns) enables one to determine the critical pressure for cell detachment with reliable statistics while minimizing the artifacts arising from the inelastic deformation of cells. The adhesion strength also exhibited a transition from weak adhesion to strong adhesion within the same elasticity range (E similar to 1-20 kPa). A clear correlation between the cell morphology and adhesion strength suggests the coupling of the strain of the substrate and the mechanosensors near focal adhesion sites.

DOI： 10.1021/jp4008224

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Biomechanical dynamic interactions between cells and the extracellular environment dynamically regulate physiological tissue behavior in living organisms, such as that seen in tissue maintenance and remodeling. In this study, the substrate-induced modulation of synchronized beating in cultured cardiomyocyte tissue was systematically characterized on elasticity-tunable substrates to elucidate the effect of biomechanical coupling. We found that myocardial conduction is significantly promoted when the rigidity of the cell culture environment matches that of the cardiac cells (4 kiloPascals). The stability of spontaneous target wave activity and calcium transient alternans in high frequency-paced tissue were both enhanced when the cell substrate and cell tissue showed the same rigidity. By adapting a simple theoretical model, we reproduced the experimental trend on the rigidity matching for the synchronized excitation. We conclude that rigidity matching in cell-to-substrate interactions critically improves cardiomyocyte-tissue synchronization, suggesting that mechanical coupling plays an essential role in the dynamic activity of the beating heart.

DOI： 10.1016/j.bpj.2011.12.018

Language：English  

DOI： 10.1016/j.bpj.2011.11.3885

Language：English   Publishing type：Research paper (scientific journal)  

Directional cell migration induced by a mechanical gradient on a substrate surface toward a harder region, so-called mechanotaxis or durotaxis, has recently drawn attention not only in the field of mechanobiology but also for possible cell manipulation in biomedical engineering. Before we can use mechanotaxis to control cell migration on a biomaterial surface, quantitative design criteria for a microelasticity gradient should be established. To clarify the conditions required to induce mechanotaxis, the effects of a microelasticity boundary on cell culture hydrogels have been systematically assessed with regard to fibroblast migration based on a custom-built reduction projection-type photolithographic microelasticity patterning system with elasticity-tunable photocurable styrenated gelatins, which is a thoroughly-improved system of our previous simple photomasking method [41]. As a result, the conditions required to induce mechanotaxis were found to include a certain threshold jump in elasticity (30-40 kPa) and a sufficiently narrow width of the elasticity boundary (50 pm) comparable to a single cell's adhered area, i.e., a sufficiently high gradient strength (30-40 kPa/50 pm in our gelatinous gel system). A significant asymmetric distribution of the number and size of focal adhesions across the elasticity boundary was confirmed to be one of the driving factors of mechanotaxis by indirect immunofluorescence microscopy, and mechanistic considerations in the design criteria are discussed. (C) 2011 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.biomaterials.2011.01.009

Language：English   Publishing type：Research paper (scientific journal)  

A flow-stretching assay was employed to elucidate polycation/DNA interactions at the single-molecule level. Bacteriophage lambda-DNA (48.5 kbp) was attached at one end to a PEG-modified glass surface and stretched by buffer flow. The stretched DNA had an approximate length of 12 mu m. Upon injection of polylysine homopolymer, the DNA folded into a globule structure within a few seconds. Injection of a polylysine graft copolymer having hydrophilic dextran side chains also induced collapse of the stretched DNA. In comparison to these polymer, a copolymer with higher graft content did not cause DNA collapse but rather caused 25% shrinkage of the extended DNA. These results were compared with those observed with unstretched DNA.

DOI： 10.1246/cl.2011.250

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

To develop a drug carrier that enables time-programmed dual release in a single formulation, multilayered drug-loaded biodegradable nanofiber meshes were designed using sequential electrospinning with the following construction: (i) first drug-loaded mesh (top), (ii) barrier mesh, (iii) second drug-loaded mesh, and (iv) basement mesh (bottom). The drug release speed and duration were controlled by designing morphological features of the electrospun meshes such as the fiber diameter and mesh thickness. Control of the timed release of the second drug-the retardation period-was accomplished by appropriate design of the barrier mesh thickness. An in vitro release experiment demonstrated that the tetra-layered construction described above with appropriate morphological features of each component mesh can provide timed dual release of the respective drugs. The time-programmed dual release system using the multilayered electrospun nanofiber meshes was demonstrated as a useful formulation for advanced multidrug combination therapy requiring regiospecific administration of different drugs at different times. The potential use of the present multilayered formulation is discussed for application to biochemical modulation as one administrative strategy for use in sequential chemotherapy employing multiple anti-tumor drugs. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jconrel.2009.12.029

Language：English   Publishing type：Research paper (scientific journal)  

We used poly(N-isopropylacrylamide) (PNIPAM) to control the conformation of genomic DNA by changing the temperature of a reaction solution and studied the DNA transition at the level of single DNA molecules. With this method, the conformation of long genomic DNA can be readily and reversibly switched between it very compact condensate and an unfolded macromolecule.

DOI： 10.1021/la904375k

Language：English  

DOI： 10.1016/j.bpj.2009.12.3998

Language：English   Publishing type：Research paper (scientific journal)  

We developed a hydrogel self-assembling method driven by the interaction between recombinant tax-interactive protein-1 (TIP1) with the PDZ domain in a molecule, which is fused to each end of the triangular trimeric CutA protein (CutA-TIP1), and a PDZ domain-recognizable peptide which is covalently bound to each terminus of four-armed poly(ethylene glycol) (PDZ-peptide-PEG). Genetic manipulation based on molecular-dynamic simulation generated a cell-adhesive RGD tripeptidyl sequence in the CutA loop region [CutA(RGD)-TIP1]. Spontaneous viscoelastic hydrogel formation occurred when either CutA-TIP1- or CutA(RGD)-TIP1-containing buffer solution and PDZ-peptide-PEG-containing buffer solutions were stoichiometrically mixed. Dynamic viscoelasticity measurement revealed shear stress-dependent reversible-phase transformation: a spontaneous viscoelastic hydrogel was formed at low shear stress, but it was transformed into a sol at high shear stress. Upon the cessation of shear, hydrogel was restored. When chondrocytes were pre-mixed with one of these two components containing buffer solutions, the stoichiometric mixed solution was also spontaneously gelled. Individual rounded cells and multicellular aggregates were entrapped within both hydrogels without substantial cellular impairment regardless of the presence or absence of RGD motif in the CutA-TIP1 molecule. The potential use of such a shear-sensitive hydrogel for injectable cell delivery into diseased or lost cartilage tissue is discussed. (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.biomaterials.2009.09.026

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

The understanding and realization of directional cell movement towards a harder region of a cell culture substrate surface, so-called mechanotaxis, might provide a solid basis for a functional artificial extracellular matrix, enabling manipulation and elucidation of cell motility. The photolithographic surface microelasticity patterning method was developed for fabricating a cell-adhesive hydrogel with a microelasticity gradient (MEG) surface using photocurable styrenated gelatin to investigate the condition of surface elasticity to induce mechanotaxis as a basis for such substrate-elasticity-dependent control of cell motility. Patterned MEG gels consisting of different absolute surface elasticities and elasticity jumps were prepared. Surface elasticity and its two-dimensional distribution were characterized by microindentation tests using atomic force microscopy (AFM). From analyses of trajectories of 3T3 cell movement on each prepared MEG gel, two critical criteria of the elasticity jump and the absolute elasticity to induce mechanotaxis were identified: (1) a high elasticity ratio between the hard region and the soft one, and (2) elasticity of the softer region to provide medium motility. Design of these conditions was found to be necessary for fabricating an artificial extracellular matrix to control or manipulate cell motility. (c) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jbiotec.2007.08.015

Language：Japanese  

Energy Landscape Analysis of the Biomolecular Interactions

DOI： 10.1295/kobunshi.56.844

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

The relationships between the structural features and mechanical properties of electrospun segmented polyurethane (SPU) meshes and electrospinning parameters such as formulation (e.g., polymer concentration and solvent mixing ratio) and operation parameters (e.g., applied voltage, air gap, and flow rate) were studied with the use of a mixed-solvent system of tetrahydrofuran (THF) and N,N-dimethylacrylamide (DMF). After the relationships between the structure of electrospun SPU and the operation parameters under a fixed SPU concentration of single THF solution were established, SPU was electrospun from the mixed solvent of THF and DMF with different mixing ratios [DMF content: 5, 10, and 30% (v/v)]. Scanning electron microscopy showed that an increase in DMF ratio significantly enhances the degree of bonding between SPU fibers at contact sites and decreases the diameter of fibers formed. The porosimetric characterization showed the following: (1) The porosity of the electrospun SPU meshes decreased with an increase of DMF ratio. (2) The pore size distribution exhibited three representative peaks of different void sizes (i.e., approximately 5, 20, and 70 μm). (3) The proportion of the 20-μm void markedly decreased with an increase in DMF ratio. A tensile test on the meshes showed that an increase in DMF ratio induces an increase in elasticity of the mesh. Such a regulation of the structural features and mechanical properties of electrospun SPU meshes using a mixed-solvent system with low- and high-boiling-point solvents may be useful in the engineering of SPU-fiber based matrices or scaffolds. © 2005 Wiley Periodicals, Inc.

DOI： 10.1002/jbm.b.30336

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

To determine the intermolecular force on protein-protein interaction (PPI) by atomic force microscopy (AFM), a photograft-polymer spacer for protein molecules on both surfaces of the substrate and AFM probe tip was developed, and its effectiveness was assessed in a PPI model of a pair of human serum albumin (HSA) and its monoclonal antibody (anti-HSA). A carboxylated photoiniferter, N-(dithiocarboxy)sarcosine, was derivatized on both surfaces of the glass substrate and AFM probe tip, and subsequently water-soluble nonionic vinyl monomers, NN-dimethylacrylamide (DMAAm), were graft-polymerized on them upon ultraviolet light irradiation. DMAAm-photograft-polymerized spacers with carboxyl groups at the growing chain end but with different chain lengths on both surfaces were prepared. The proteins were covalently bound to the carboxyl terminus of the photograft-polymer chain using a water-soluble condensation agent. The effects of the graft-spacer length on the profile of the force-distance curves and on the unbinding characteristics (unbinding force and unbinding distance) were examined in comparison with those in the case of the commercially available poly(ethylene glycol) (PEG) spacer. The frequency of the nonspecific adhesion force profile was markedly decreased with the use of the photograft spacers. Among the force curves detected, a high frequency of single-peak curves indicating the unbinding process of a single pair of proteins and a very low frequency of multiple-peak profiles were observed for the photograft spacers, regardless of the graft chain length, whereas a high frequency of no-force peaks was noted. These observations were in marked contrast with those for the PEG spacer. The force peak values determined ranged from 88 to 94 pN, irrespective of the type of spacer, while the standard deviation of force distribution observed for the photograft spacer was lower than that for the PEG spacer, indicating that the photograft spacers provide a higher accuracy of force determination.

DOI： 10.1021/bm0502617

Language：English   Publishing type：Research paper (scientific journal)  

Nano- to micro-structured biodegradable poly(L-lactide-co-epsilon-caprolactone) (PLCL) fabrics were prepared by electrospinning. Electrospun microfiber fabrics with different compositions of PLCL (mol% in feed; 70/30, 50150, and 30/70), poly(L-lactide) (PLL) and poly(c-caprolactone) (PCL) were obtained using methylene chloride (MC) as a solvent. The PLL microfiber exhibited a nanoscale-pore structure with a pore diameter of approximately 200-800 mn at the surface and subsurface regions, whereas such a surface structure was hardly observed in other polymers containing CL. The microfiber fabric made of PLCL 50/50 was elastomeric. Nanoscale-fiber fabrics with PLCL 50/50 (approx. 0.3 or 1.2 mum in diameter) were electrospun using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as a solvent. Mercury porosimetry showed that the decrease in the fiber diameter of the fabric decreased porosity, but increased fiber density and mechanical strength. Human umbilical vein endothelial cells (HUVECs) were adhered well and proliferated on the small-diameter-fiber fabrics (0.3 and 1.2 mum in diameter), both of which are dense fabrics, whereas markedly reduced cell adhesion, restricted cell spreading and no signs of proliferation were observed on the large-diameter-fiber fabric (7.0 mum in diameter), The potential biomedical application of electrospun PLCL 50/50 was discussed. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.biomaterials.2004.10.007

Language：English   Publishing type：Research paper (scientific journal)  

Poly(jV-isopropylacrylamide)-grafted gelatin (PNIPAM-gelatin) serves as a temperature-induced scaffold at physiological temperature. This study was aimed at determining the effect of the graft architecture of thermoresponsive PNIPAM-gelatin on the surface topography and elastic modulus of the hydrogels prepared with different architectured PNIPAM-gelatins: the surface topography and elastic modulus were determined by atomic force microscopy (AFM). PNIPAM-gelatin surfaces showed an irregularly concavo-convex structure with a vertical interval of approximately I pm regardless of the weight ratio of PNIPAM to gelatin (P/G: 5.8, 12, and 18). The elastic moduli of hydrogels varied at measured sites. The mean elastic moduli of PNIPAM-gelatin with the lowest P/G were low, but increased with increasing P/G. Human umbilical vein endothelial cells adhered and spread on PNIPAM-gelatin hydrogels with the highest P/G, whereas reduced adhesion and nonspreading, round-shaped cells resided on the hydrogels with lower P/Gs. Interrelationship between elastic modulus and cell adhesion and spreading potentials were discussed from physicochemical and cellular biomechanical viewpoints. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.biomaterials.2004.08.006

Language：English   Publishing type：Research paper (scientific journal)  

To fabricate a "mechano-active" tubular scaffold of nonwoven mesh-type small-diameter artificial graft made of the synthetic durable elastomer, segmented polyurethane, the fabrication technique of electrospinning on a mandrel under a high rotation speed and transverse movement was used. Emphasis was placed on how the rotation speed of the mandrel and the fusion or welding states of fibers at contact points affect the compliance (ease of intraluminal pressure-dependent circumferential inflation) and Young's modulus determined by uniaxial stretching in the longitudinal and circumferential directions. The results showed that a high rotation speed is attributed to exhibit isotropic mechanical properties in the entire range of applied strain but reduces the compliance, and a high fusion state, which is produced using a mixed solvent with a high content of high-boiling-point solvent, reduces the compliance but is expected to exhibit high durability in a continuously loaded pulsatile stress field in an arterial circulatory system. © 2005 Wiley Periodicals, Inc.

DOI： 10.1002/jbm.a.30260

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/masy.200550618

Language：English   Publishing type：Research paper (scientific journal)  

To design a mesoscopically ordered structure of the matrices and scaffolds composed of nano- and microscale fiber meshes for artificial and tissue-engineering devices, two new electrospinning techniques are proposed: multilayering electrospinning and mixing electrospinning. First, the following four kinds of component polymers were individually electrospun to determine the conditions for producing stable nano- and microfibers by optimizing the formulation parameters (solvent and polymer concentration) and operation parameters (voltage, air gap, and flow rate) for each polymer: (a) type I collagen, (b) styrenated gelatin (ST-gelatin), (c) segmented polyurethane (SPU), and (d) poly(ethylene oxide). A trilayered electrospun mesh, in which individual fiber meshes (type I collagen, ST-gelatin, and SPU) were deposited layer by layer, was formed by sequential electrospinning; this was clearly visualized by confocal laser scanning microscopy. The mixed electrospun-fiber mesh composed of SPU and PEO was prepared by simultaneous electrospinning on a stainless-steel mandrel with high-speed rotation and traverse movement. A bilayered tubular construct composed of a thick SPU microfiber mesh as an outer layer and a thin type I collagen nanofiber mesh as an inner layer was fabricated as a prototype scaffold of artificial grafts, and visualized by scanning electron microscopy. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.biomaterials.2004.01.063

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1186/gb-2005-6-12-r98

Language：English   Publishing type：Research paper (scientific journal)  

Various photocurable liquid biodegradable trimethylene carbonate (TMC)-based (co)oligomers were prepared by ring-opening (co)polymerization of TMC with or without L-lactide (LL) using low molecular weight poly(ethylene glycol) (PEG) (mol wt 200, 600, or 1000) or trimethylolpropane (TMP) as an initiator. Resultant (co)oligomers were pastes, viscous liquids, or liquids at room temperature, depending on the monomer composition and monomer/initiator ratio. Liquid (co)oligomers were subsequently end-capped with acrylate groups. Upon visible-light irradiation in the presence of camphorquinone as a radical generator, rapid liquid-to-solid transformation occurred to produce photocured solid. The photocuring yield increased with photoirradiation time, photointensity, and camphorquinone concentration. The photocured polymers derived from low molecular weight PEG (PEG200) and TMP exhibited much reduced hydrolysis potential compared with PEG1000-derived polymers in terms of weight loss, water uptake, and swelling depth. Force-distance curve measurements by nanoindentation using atomic force microscopy clearly showed that Young's moduli of the photocured polymer films decreased with increasing hydrolysis time. Their potential biomedical applications are discussed.

DOI： 10.1021/bm034231k

Language：English   Publishing type：Research paper (scientific journal)  

It has been established that in a dilute solution individual giant DNA molecules undergo a large discrete transition between an elongated coil state and a folded compact state. On the other hand, in concentrated solutions, DNA molecules assemble into various characteristic states, including multichain aggregate, liquid crystalline, ionic crystal, etc. In this study, we compared single-chain and multiple-chain events by observing individual chains using fluorescence microscopy. We used spermidine, SPD(3+), as a condensing agent for giant DNA. When the concentration of DNA is below 1 muM in base-pair units, individual DNA molecules exhibit a transition from an elongated state to a compact state. When the concentration of DNA is increased to 10 muM, a thick fiberlike assembly of multiple chains appears. AFM measurements of this thick fiber revealed that more than tens of DNA molecules form a bundle structure with parallel ordering of the chains. The transition between single-chain compaction and bundle formation with multiple-chain assemblies was reproduced by a theoretical calculation. (C) 2004 American Institute of Physics.

DOI： 10.1063/1.1642610

Language：Others  

Substrate-dependent cellular behavior of Swiss 3T3 fibroblasts and activation of Rho family during adhesion and spreading processes.

DOI： 10.1002/jbm.a.20012

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

To directly characterize the thermoresponsive structural changes of a poly(N-isopropylacrylamide) (PNIPAAm) graft layer at the microscopic level, the force-distance curve (f-d curve) was measured on a well-tailored end-grafted PNIPAAm surface in aqueous solution at 25 and 40 degreesC, using an atomic force microscope (AFM). The PNIPAAm surface was prepared by an iniferter-based photograft polymerization technique. The approach trace of the f-d curve exhibited a steric repulsion profile at 25 degreesC, while the range of repulsion decreased 1/10 to 1/20 at 40 degreesC, confirming the ascending-heat induced collapse of the PNIPAAm graft layer. The change in thickness of the graft layer was complementarily measured from the scanning images of the boundary between the grafted and nongrafted regions under well-defined scanning forces. The thermoresponsive characteristics of the PNIPAAm graft layer including its interaction with proteins and the applied-load dependence of the measured graft thickness are discussed.

Language：English   Publishing type：Research paper (scientific journal)  

To investigate the characteristics of interaction forces between proteins and end-grafted polymer surfaces, force-versus-distance curves (f-d curves) were measured between protein-fixed probe tips (albumin (Alb) and lysozyme (Lyso)) and surfaces graft-polymerized with N,N-dimethylacrylamide (DMAAm) or acrylic acid (AAc) in an aqueous solution, using an atomic force microscope. DMAAm graft-polymerized surfaces with different chain lengths and AAc graft-polymerized surface were prepared by photopolymerization on a dithiocarbamate (iniferter)-immobilized surface. The effects of grafted chain length, grafting density, and electrostatic property of the grafted chain segments on the interaction forces in the processes of protein adsorption onto and desorption from the graft-polymerized surfaces were analyzed from the approaching and retracting traces of the observed f-d curves, respectively. (1) In the Alb/poly(DMAAm) system, steric repulsion was observed, in which the interaction range and the compressive force of the poly(DMAAm) layer linearly increased with increasing chain length of poly(DMAAm) except for very short chain lengths. Adhesion force was observed only for the poly(DMAAm) layer with short chains. (2) In the Alb/poly(AAc) system, repulsive force due to steric and electrostatic interactions, and "tooth-like" adhesion forces were observed. (3) In the Lyso/poly(AAc) system, electrostatic attraction and adhesion forces were observed. From observation 1, the grafting density, the elastic modulus of the poly(DMAAm) layer, and the conformation of the grafted chain ("mushroom" or "brush") were deduced and are discussed in relation to the characteristics of the interaction force with the proteins. From observations 2 and 3, it was found that a polyanionic surface can provide a significant adhesion force not only to positively charged proteins but also to negatively charged ones at physiological pH.

DOI： 10.1021/la000003p

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese  

Application of Fluorescence Microscopy for the Single Molecular Observation of Giant Duplex DNA Chain

DOI： 10.1295/kobunshi.46.252

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Book type：General book, introductory book for general audience

Language：English   Book type：Scholarly book

Responsible for pages：in press   Language：English   Book type：Scholarly book

Language：Japanese   Book type：Scholarly book

Language：Japanese   Book type：Scholarly book

Language：Japanese   Book type：Scholarly book

Language：Japanese   Book type：Scholarly book

Responsible for pages：第2章5節　 "PEGによるDNA折り畳みの理論" 第4章　　"DNAとカチオンの相互作用II：巨大DNAのコンフォメーション・アッセイによる解析"   Language：Japanese   Book type：Scholarly book

Event date： 2023.7

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Venue：万国津梁館、沖縄   Country：Japan  

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Country：Japan  

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Venue：Online   Country：Japan  

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Venue：Online   Country：Japan  

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2023.5

Language：English   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2023.5

Language：English   Presentation type：Oral presentation (general)  

Venue：千葉   Country：Japan  

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.6

Language：English   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.12

Language：Japanese  

Venue：オンライン   Country：Japan  

Event date： 2021.12

Language：Japanese  

Venue：オンライン   Country：Japan  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.9 - 2021.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.7

Language：English  

Venue：オンライン   Country：Japan  

Event date： 2021.7

Language：English   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.3 - 2022.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.2

Language：English  

Venue：オンライン   Country：United States  

Event date： 2021.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2020.12

Language：English   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：web開催   Country：Japan  

Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：web開催   Country：Japan  

Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：web開催   Country：Japan  

Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：web開催   Country：Japan  

Event date： 2020.5

Language：Japanese  

Venue：web開催   Country：Japan  

Event date： 2020.5

Language：Japanese  

Venue：web開催   Country：Japan  

Event date： 2020.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：web開催   Country：Japan  

Event date： 2019.12

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.12

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学   Country：Japan  

Event date： 2019.11

Language：English   Presentation type：Oral presentation (general)  

Venue：東京理科大学   Country：Japan  

Event date： 2019.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：つくば   Country：Japan  

Event date： 2019.11

Language：English   Presentation type：Oral presentation (general)  

Venue：北九州   Country：Japan  

Event date： 2019.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Okinawa   Country：Japan  

Event date： 2019.11

Language：English  

Venue：Okinawa   Country：Japan  

Event date： 2019.10

Language：English   Presentation type：Oral presentation (general)  

Venue：ザールラント大学   Country：Germany  

Event date： 2019.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井大学   Country：Japan  

Event date： 2019.9

Language：English  

Venue：宮崎   Country：Japan  

Event date： 2019.9

Language：English  

Venue：宮崎   Country：Japan  

Event date： 2019.9

Language：English  

Venue：宮崎   Country：Japan  

Event date： 2019.9

Language：English  

Venue：宮崎   Country：Japan  

Event date： 2019.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京工業大学   Country：Japan  

Event date： 2019.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岐阜大学   Country：Japan  

Event date： 2019.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：天城   Country：Japan  

Event date： 2019.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：香川研直島   Country：Japan  

Event date： 2019.9

Language：Japanese  

Venue：東京   Country：Japan  

Event date： 2019.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：熊本   Country：Japan  

Event date： 2019.7

Language：Japanese  

Country：Japan  

Event date： 2019.7

Language：Japanese  

Country：Japan  

Event date： 2019.6

Language：English  

Venue：Los Angeles Convention Center   Country：United States  

Event date： 2019.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：神戸国際会議場   Country：Japan  

Event date： 2019.6 - 2019.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：札幌   Country：Japan  

Event date： 2019.5

Language：Japanese  

Venue：大阪   Country：Japan  

Event date： 2019.3

Language：Japanese  

Venue：神戸   Country：Japan  

Event date： 2019.3

Language：Japanese  

Venue：東京   Country：Japan  

Event date： 2019.3

Language：English   Presentation type：Oral presentation (general)  

Venue：京都   Country：Japan  

Event date： 2019.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡   Country：Japan  

Event date： 2019.1

Language：Japanese  

Venue：大阪   Country：Japan  

Event date： 2019.1

Language：English   Presentation type：Oral presentation (general)  

Venue：京都   Country：Japan  

Event date： 2018.12

Language：English   Presentation type：Oral presentation (general)  

Venue：北九州   Country：Japan  

Event date： 2018.12

Language：English   Presentation type：Oral presentation (general)  

Venue：Melbourne   Country：Australia  

Event date： 2018.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：横浜   Country：Japan  

Event date： 2018.11

Language：English  

Venue：東京   Country：Japan  

Event date： 2018.11

Language：Japanese  

Venue：神戸   Country：Japan  

Event date： 2018.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：千葉   Country：Japan  

Event date： 2018.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2018.9

Language：Japanese  

Venue：岡山   Country：Japan  

Event date： 2018.9

Language：Japanese  

Venue：岡山   Country：Japan  

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：札幌   Country：Japan  

Event date： 2018.9

Language：English  

Venue：京都   Country：Japan  

Event date： 2018.9

Language：English  

Venue：Harrogate   Country：United Kingdom  

Event date： 2018.9

Language：English  

Venue：Harrogate   Country：United Kingdom  

Event date： 2018.9

Language：English  

Venue：Harrogate   Country：United Kingdom  

Event date： 2018.7

Language：English   Presentation type：Oral presentation (general)  

Venue：沖縄   Country：Japan  

Event date： 2018.6

Language：English  

Venue：メルボルン   Country：Australia  

Event date： 2018.6 - 2019.5

Language：Japanese  

Venue：東京   Country：Japan  

Event date： 2018.3

Language：Japanese  

Venue：横浜   Country：Japan  

Event date： 2018.3

Language：English   Presentation type：Oral presentation (general)  

Venue：福岡   Country：Japan  

Event date： 2018.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京大学   Country：Japan  

Event date： 2018.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪   Country：Japan  

Event date： 2018.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：北九州   Country：Japan  

Event date： 2018.1

Language：Japanese   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

Country：Japan  

Event date： 2017.12

Language：English  

Venue：北九州   Country：Japan  

Event date： 2017.12

Language：English  

Venue：北九州   Country：Japan  

Event date： 2017.12

Language：English  

Venue：北九州   Country：Japan  

Event date： 2017.12

Language：Japanese  

Venue：京都   Country：Japan  

Event date： 2017.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：京都   Country：Japan  

Event date： 2017.12

Language：English   Presentation type：Oral presentation (general)  

Venue：Singapore   Country：Japan  

Event date： 2017.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：神戸   Country：Japan  

Event date： 2017.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Sendai   Country：Japan  

Event date： 2017.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2017.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：京都   Country：Japan  

Event date： 2017.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岩手   Country：Japan  

Event date： 2017.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岩手   Country：Japan  

Event date： 2017.9

Language：Japanese  

Venue：松山   Country：Japan  

Event date： 2017.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：松山   Country：Japan  

Event date： 2017.9

Language：English   Presentation type：Oral presentation (general)  

Venue：熊本   Country：Japan  

Event date： 2017.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：神戸   Country：Japan  

Event date： 2017.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡   Country：Japan  

Event date： 2017.8 - 2017.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Kyoto   Country：Japan  

Event date： 2017.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Taoyuan   Country：Taiwan, Province of China  

Event date： 2017.8

Language：English  

Venue：Fukuoka   Country：Japan  

Event date： 2017.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：北九州市   Country：Japan  

Event date： 2017.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Brisbane   Country：Australia  

Event date： 2017.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Brisbane   Country：Australia  

Event date： 2017.6

Language：English  

Venue：Taipei   Country：Taiwan, Province of China  

Event date： 2017.6

Language：English  

Venue：Boston   Country：Armenia  

Event date： 2017.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東北大学医学部星稜キャンパス   Country：Japan  

Event date： 2017.3

Language：Japanese  

Venue：京都大学   Country：Japan  

Event date： 2017.3

Language：Japanese  

Venue：仙台国際センター   Country：Japan  

Event date： 2017.3

Language：Japanese  

Venue：仙台国際センター   Country：Japan  

Event date： 2017.3

Language：Japanese  

Venue：仙台国際センター   Country：Japan  

Event date： 2017.3

Language：English  

Venue：日本大学　津田沼キャンパス   Country：Japan  

Event date： 2017.3

Language：Japanese  

Venue：芝浦工業大学   Country：Japan  

Event date： 2017.3

Language：Japanese  

Venue：東京理科大学   Country：Japan  

Event date： 2017.2

Language：English  

Venue：New Orleans   Country：United States  

Event date： 2017.1

Language：Japanese  

Venue：九州大学　西新プラザ   Country：Japan  

Event date： 2017.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学　西新プラザ   Country：Japan  

Event date： 2016.12

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka International Congress Center   Country：Japan  

Event date： 2016.11

Language：Japanese  

Venue：つくば国際会議場   Country：Japan  

Event date： 2016.11

Language：Japanese  

Venue：つくば国際会議場   Country：Japan  

Event date： 2016.11

Language：Japanese  

Venue：福岡国際会議場   Country：Japan  

Event date： 2016.11

Language：Japanese  

Venue：福岡国際会議場   Country：Japan  

Event date： 2016.11

Language：Japanese  

Venue：福岡国際会議場   Country：Japan  

Event date： 2016.11

Language：Japanese  

Venue：福岡国際会議場   Country：Japan  

Event date： 2016.9

Language：English  

Venue：National University of Singapore   Country：Singapore  

Event date： 2016.9

Language：Japanese  

Venue：神奈川大学   Country：Japan  

Event date： 2016.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：神奈川大学   Country：Japan  

Event date： 2016.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：神奈川大学   Country：Japan  

Event date： 2016.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2016.6 - 2016.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Bangkok   Country：Thailand  

Event date： 2016.5

Language：English  

Venue：Montreal   Country：Canada  

Event date： 2016.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：北海道大学　理学部   Country：Japan  

Event date： 2016.1

Language：English   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2015.12

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Venue：東京   Country：Japan  

Event date： 2015.11

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Country：Japan  

Event date： 2015.11

Language：English   Presentation type：Oral presentation (general)  

Venue：名古屋   Country：Japan  

Event date： 2015.11

Language：Japanese  

Venue：京都   Country：Japan  

Event date： 2015.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：品川   Country：Japan  

Event date： 2015.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Kyoto   Country：Japan  

Event date： 2015.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Sapporo   Country：Japan  

Event date： 2015.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Sapporo   Country：Japan  

Event date： 2015.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：仙台   Country：Japan  

Event date： 2015.9

Language：Japanese  

Venue：金沢   Country：Japan  

Event date： 2015.9

Language：Japanese  

Venue：金沢   Country：Japan  

Event date： 2015.8 - 2015.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Krakow   Country：Poland  

Event date： 2015.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Tsukuba   Country：Japan  

Event date： 2015.7 - 2014.7

Language：English   Presentation type：Oral presentation (general)  

Venue：エポカルつくば   Country：Japan  

Event date： 2014.11

Language：Japanese  

Venue：タワーホール船堀   Country：Japan  

Event date： 2014.11

Language：Japanese  

Venue：タワーホール船堀   Country：Japan  

Event date： 2014.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎大学   Country：Japan  

Event date： 2014.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎大学   Country：Japan  

Event date： 2014.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学椎木講堂   Country：Japan  

Event date： 2014.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学医学部百年記念講堂   Country：Japan  

Event date： 2014.8

Language：English   Presentation type：Oral presentation (general)  

Venue：San Francisco Hall   Country：United States  

Event date： 2014.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：北海道大学工学部   Country：Japan  

Event date： 2014.5

Language：English   Presentation type：Oral presentation (general)  

Venue：岡山大学   Country：Japan  

Event date： 2014.5

Language：English   Presentation type：Oral presentation (general)  

Venue：岡山大学   Country：Japan  

Event date： 2014.2

Language：English   Presentation type：Oral presentation (general)  

Venue：北海道大学学術交流会館   Country：Japan  

Event date： 2014.1

Language：English   Presentation type：Oral presentation (general)  

Venue：Icho Kaikan, Osaka University   Country：Japan  

Event date： 2013.12

Language：English   Presentation type：Oral presentation (general)  

Venue：National University of SIngapore   Country：Singapore  

Event date： 2013.11

Language：Japanese  

Venue：タワーホール船堀   Country：Japan  

Event date： 2013.11

Language：Japanese  

Venue：タワーホール船堀   Country：Japan  

Event date： 2013.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：タワーホール船堀   Country：Japan  

Event date： 2013.10

Language：Japanese  

Venue：国立京都国際会議場   Country：Japan  

Event date： 2013.10

Language：Japanese  

Venue：国立京都国際会議場   Country：Japan  

Event date： 2013.10

Language：Japanese  

Venue：国立京都国際会議場   Country：Japan  

Event date： 2013.10

Language：Japanese  

Venue：国立京都国際会館   Country：Japan  

Event date： 2013.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：金沢大学　角間キャンパス   Country：Japan  

Event date： 2013.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：金沢大学角間キャンパス   Country：Japan  

Event date： 2013.8

Language：English   Presentation type：Oral presentation (general)  

Venue：韓国済州島グランドホテル   Country：Korea, Republic of  

Event date： 2013.7

Language：English  

Venue：Sydney InterContinental Hotel   Country：Australia  

Event date： 2013.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学西新プラザ   Country：Japan  

Event date： 2012.3

Presentation type：Oral presentation (general)  

Venue：慶応大学日吉キャンパス   Country：Japan  

Event date： 2012.2

Venue：サンディエゴコンベンションセンター   Country：United States  

Event date： 2012.2

Presentation type：Oral presentation (general)  

Venue：工学院大学新宿キャンパス   Country：Japan  

Event date： 2011.12

Venue：横浜市開港記念会館、横浜情報文化センター   Country：Japan  

Event date： 2011.12

Venue：横浜市開港記念会館、横浜情報文化センター   Country：Japan  

Event date： 2011.12

Venue：横浜市開港記念会館、横浜情報文化センター   Country：Japan  

Event date： 2011.12

Venue：横浜市開港記念会館、横浜情報文化センター   Country：Japan  

Event date： 2011.12

Venue：Marriot Resort, Waikoloa, Hawaii   Country：Japan  

Event date： 2011.12

Presentation type：Oral presentation (general)  

Venue：京都大学再生医科学研究所   Country：Japan  

Event date： 2011.11 - 2011.12

Presentation type：Oral presentation (general)  

Venue：Kyoto Terusa   Country：Japan  

Event date： 2011.11

Presentation type：Oral presentation (general)  

Venue：Shanghai Huashia Hotel   Country：Japan  

Event date： 2011.9

Presentation type：Oral presentation (general)  

Venue：岡山大学津島キャンパス   Country：Japan  

Event date： 2011.9

Presentation type：Oral presentation (general)  

Venue：Kyushu University Chikushi Campus, C-Cube   Country：Japan  

Event date： 2011.3

Presentation type：Oral presentation (general)  

Venue：九州大学医学部百年講堂   Country：Japan  

Event date： 2010.11

Presentation type：Oral presentation (general)  

Venue：National University of Singapore, Mechanobiology Institute   Country：Singapore  

Event date： 2010.9

Presentation type：Oral presentation (general)  

Venue：東北大学川内キャンパス   Country：Japan  

Event date： 2010.9

Presentation type：Oral presentation (general)  

Venue：東北大学川内キャンパス   Country：Japan  

Event date： 2010.9

Presentation type：Oral presentation (general)  

Venue：東北大学川内キャンパス   Country：Japan  

Event date： 2010.9

Presentation type：Oral presentation (general)  

Venue：東北大学川内キャンパス   Country：Japan  

Event date： 2010.9

Presentation type：Oral presentation (general)  

Venue：北海道大学高等教育機能開発総合センター   Country：Japan  

Event date： 2010.9

Presentation type：Oral presentation (general)  

Venue：北海道大学高等教育機能開発総合センター   Country：Japan  

Event date： 2010.8

Presentation type：Oral presentation (general)  

Venue：洞爺湖サンパレス   Country：Japan  

Event date： 2010.6

Presentation type：Oral presentation (general)  

Venue：竹輝飯店（蘇州市）   Country：China  

Event date： 2010.3

Presentation type：Oral presentation (general)  

Venue：Hotel Nidom, Hokkaido   Country：Japan  

Event date： 2010.2

Presentation type：Oral presentation (general)  

Venue：San Fransisco   Country：United States  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：休暇村　志賀島   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京工業大学 キャンパスイノベーションセンター   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡国際会議場   Country：Japan  

Language：English   Presentation type：Oral presentation (general)  

Venue：西安ガーデンホテル   Country：China  

Language：Japanese  

Venue：志賀島   Country：Japan  

Language：Japanese  

Venue：志賀島   Country：Japan  

Language：English   Presentation type：Oral presentation (general)  

Venue：Yasuda Auditorium, Hongo Campus The University of Tokyo   Country：Japan  

Language：Japanese  

Venue：名古屋大学   Country：Japan  

Language：Japanese  

Venue：名古屋大学   Country：Japan  

Language：English   Presentation type：Oral presentation (general)  

Venue：Hyatt Regency Waikiki Beach Resort and Spa   Country：United States  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：北九州国際会議場   Country：Japan  

Language：Japanese  

Venue：仙台国際センター   Country：Japan  

Language：Japanese  

Venue：仙台国際センター   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：北大電子研   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：ラフォーレ那須   Country：Japan  

Language：Japanese   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

Venue：千葉大学   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡歯科大学   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：山形大学工学研究科   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：理化学研究所神戸   Country：Japan  

Event date： 2010.4

Presentation type：Oral presentation (general)  

Venue：シェーンバッハ・サボー（東京都千代田区　砂防会館別館）   Country：Japan  

Event date： 2009.11

Presentation type：Oral presentation (general)  

Venue：京都テルサ   Country：Japan  

Event date： 2009.11

Presentation type：Oral presentation (general)  

Venue：京都テルサ   Country：Japan  

Event date： 2009.11

Presentation type：Oral presentation (general)  

Venue：京都テルサ   Country：Japan  

Event date： 2009.11

Venue：東京大学　武田ホール   Country：Japan  

Event date： 2009.11

Venue：東京大学　武田ホール   Country：Japan  

Event date： 2009.11

Presentation type：Oral presentation (general)  

Venue：東京大学　武田ホール   Country：Japan  

Event date： 2009.10 - 2009.11

Venue：アスティ徳島   Country：Japan  

Event date： 2009.10 - 2009.11