Publications

Maryam Eshrati, Federico Amadei, Tom Van de Wiele, Mariam Veschgini, *Stefan Kaufmann, *Motomu Tanaka,
Biopolymer-based minimal formulations boost viability and metabolic functionality of probiotics lactobacillus rhamnosus GG through gastrointestinal passage,
Langmuir 34, 11167-11175 (2018).

[Summary] The delivery of probiotic microorganisms as food additives via oral administration is a straightforward strategy to improve the intestinal microbiota. To protect probiotics from the harsh environments in the stomach and small intestine, it is necessary to formulate them in biocompatible carriers, which finally release them in the ileum and colon without losing their viability and functions. Despite major progresses in various polymer-based formulations, many of them are highly heterogeneous and too large in size and hence often “felt” by the tongue. In this study, we established a new formulation for probiotics Lactobacillus rhamnosus GG (LGG) and systematically correlated the physicochemical properties of formulations with the functions of probiotics after the delivery to different gastrointestinal compartments. The obtained results have demonstrated that the minimal formulation of LGG established here boosts not only the viability but also the metabolic functionality of probiotics throughout oral uptake, passage through the gastrointestinal tract, and delivery to the ileum and colon.

Wasim Abuillan, Alexandra S. Becker, Bruno Deme, Tatsuya Homma , Hiroyuki Isobe, *Koji Harano, *Eiichi Nakamura, *Motomu Tanaka,
Neutron scattering reveals water confined in a watertight bilayer vesicle,
J. Am. Chem. Soc. 140, 11261-11266 (2018).

[Summary] Water molecules confined in a nanocavity possess distinctly different characteristics from those in bulk, yet the preparation of such nanocavities is still a major experimental challenge. We report here a selfassembled vesicle of an anionic perfluoroalkylated [60]fullerene, unique for its outstanding stability and water tightness, containing water not bound to the membranes. Small-angle neutron scattering revealed that a vesicle of 14 nm outer radius contains a 2 nm thick fullerene bilayer, inside of which is a 3 nm thick membrane-bound water and unbound water in the 4 nm innermost cavity. The vesicle shows astonishingly low water permeability that is 6 to 9 orders of magnitude smaller than that of a lipid vesicle. As a result, a single vesicle isolated on a substrate can retain the interior water in air or even under high vacuum, indicating that the vesicle cavity provides a new tool for physicochemical studies of confined water as well as ions and molecules dissolved in it.

*Takao Ohta, Cornelia Monzel, Alexandra S.Becker, Anthony D.Ho, *Motomu Tanaka,
Simple physical model unravels influences of chemokine on shape deformation and migration of human hematopoietic stem cells,
Scientific Reports 8, 10630 (2018).

[Summary] We studied the dynamic behavior of human hematopoietic stem cells (HSC) on the in vitro model of bone marrow surfaces in the absence and presence of chemokine (SDF1α). Since HSC used in this study were primary cells extracted from the human umbilical cord blood, it is not possible to introduce molecular reporter systems before or during the live cell imaging. To account for the experimental observations, we propose a simple and general theoretical model for cell crawling. In contrast to other theoretical models reported previously, our model focuses on the nonlinear coupling between shape deformation and translational motion and is free from any molecular-level process. Therefore, it is ideally suited for the comparison with our experimental results.We have demonstrated that the results in the absence of SDF1α were well recapitulated by the linear model, while the nonlinear model is necessary to reproduce the elongated migration observed in the presence of SDF1α. The combination of the simple theoretical model and the label-free, live cell observations of human primary cells opens a large potential to numerically identify the differential effects of extrinsic factors such as chemokines, growth factors, and clinical drugs on dynamic phenotypes of primary cells.

Cornelia Monzel, Alexandra S. Becker, Rainer Saffrich, Patrick Wuchter, Volker Eckstein, Anthony D. Ho & *Motomu Tanaka,
Dynamic cellular phynotyping defines specific mobilization mechanisms of human hematopoietic stem and progenitor cells induced by SDF1α versus synthetic agents,
Scientific Reports 8, 1841 (2018).

[Summary] Efficient mobilization of hematopoietic stem and progenitor cells (HSPC) is one of the most crucial issues for harvesting an adequate amount of peripheral HSPC for successful clinical transplantation. Applying well-defined surrogate models for the bone marrow niche, live cell imaging techniques, and novel tools in statistical physics, we have quantified the functionality of two mobilization agents that have been applied in the clinic, NOX-A12 and AMD3100 (plerixafor), as compared to a naturally occurring chemokine in the bone marrow, SDF1α. We found that NOX-A12, an L-enantiomeric RNA oligonucleotide to SDF1, significantly reduced the adhesion of HSPC to the niche surface mediated via the CXCR4-SDF1α axis, and stretched the migration trajectories of the HSPC. We found that the stretching of trajectories by NOX-A12 was more prominent than that by SDF1α. In contrast, plerixafor exhibited no detectable interference with adhesion and migration. We also found that the deformation of HSPC induced by SDF1α or plerixafor was also drastically suppressed in the presence of NOX-A12. This novel technology of quantitative assessment of "dynamic phenotypes" by physical tools has therefore enabled us to define different mechanisms of function for various extrinsic factors compared to naturally occurring chemokines.

Salomé Mielke, Taichi Habe, Mariam Veschgini, Xianhe Liu, Kenichi Yoshikawa, Marie Pierre Krafft, and *Motomu Tanaka,
Emergence of Strong Nonlinear Viscoelastic Response of Semifluorinated Alkane Monolayers,
Langmuir 34(7), 2489-2496 (2018).

[Summary] Viscoelasticity of monolayers of fluorocarbon/hydrocarbon tetrablock amphiphiles di(FnHm) ((CnF2n+1CH2)(Cm–2H2m–3)CH–CH(CnF2n+1CH2)(Cm–2H2m–3)) was characterized by interfacial dilational rheology under periodic oscillation of the moving barriers at the air/water interface. Because the frequency dispersion of the response function indicated that di(FnHm) form two-dimensional gels at the interface, the viscosity and elasticity of di(FnHm) were first analyzed with the classical Kelvin–Voigt model. However, the global shape of stress response functions clearly indicated the emergence of a nonlinearity even at very low surface pressures (π ≈ 5 mN/m) and small strain amplitudes (u0 = 1%). The Fourier-transformed response function of higher harmonics exhibited a clear increase in the intensity only from odd modes, corresponding to the nonlinear elastic component under reflection because of mirror symmetry. The emergence of strong nonlinear viscoelasticity of di(FnHm) at low surface pressures and strain amplitudes is highly unique compared to the nonlinear viscoelasticity of other surfactant systems reported previously, suggesting a large potential of such fluorocarbon/hydrocarbon molecules to modulate the mechanics of interfaces using the self-assembled domains of small molecules.

Marcel Hörning, Masaki Nakahata, Philip Linke, Akihisa Yamamoto, Mariam Veschgini, Stefan Kaufmann, Yoshinori Takashima, Akira Harada & *Motomu Tanaka,
Dynamic mechano-regulation of myoblast cells on supramolecular hydrogels cross-linked by reversible host-guest interactions,
Scientific Reports 7, 7660 (2017).

[Summary] A new class of supramolecular hydrogels, cross-linked by host-guest interactions between β-cyclodextrin (βCD) and adamantane, were designed for the dynamic regulation of cell-substrate interactions. The initial substrate elasticity can be optimized by selecting the molar fraction of host-
and guest monomers for the target cells. Moreover, owing to the reversible nature of host-guest interactions, the magnitude of softening and sti ening of the substrate can be modulated by varying the concentrations of free, competing host molecules (βCD) in solutions. By changing the substrate elasticity at a desired time point, it is possible to switch the micromechanical environments of cells.
We demonstrated that the Young’s modulus of our “host-guest gels”, 4–11 kPa, lies in an optimal range not only for static (ex situ) but also for dynamic (in situ) regulation of cell morphology and cytoskeletal ordering of myoblasts. Compared to other stimulus-responsive materials that can either change the elasticity only in one direction or rely on less biocompatible stimuli such as UV light and temperature change, our supramolecular hydrogel enables to reversibly apply mechanical cues to various cell types in vitro without interfering cell viability.

Takahisa Matsuzaki, Hiroaki Ito, Veronika Chevyreva, Ali Makky, Stefan Kaufmann, Kazuki Okano, Naritaka Kobayashi, Masami Suganuma, Seiichiro Nakabayashi, Hiroshi Y. Yoshikawa and *Motomu Tanaka,
Adsorption of galloyl catechin aggregates significantly modulates membrane mechanics in the absence of biochemical cues,
Physical Chemistry Chemical Physics 19, 9937-19947 (2017).

[Summary] Physical interactions of four major green tea catechin derivatives with cell membrane models were systemically investigated. Catechins with the galloyl moiety caused the aggregation of small unilamellar vesicles and an increase in the surface pressure of lipid monolayers, while those without did not. Differential scanning calorimetry revealed that, in a low concentration regime (r10 mM), catechin molecules are not significantly incorporated into the hydrophobic core of lipid membranes as substitutional impurities. Partition coefficient measurements revealed that the galloyl moiety of catechin and the cationic quaternary amine of lipids dominate the catechin–membrane interaction, which can be attributed to the combination of electrostatic and cation–p interactions. Finally, we shed light on the mechanical consequence of catechin–membrane interactions using the Fourier-transformation of the membrane fluctuation. Surprisingly, the incubation of cell-sized vesicles with 1 mM galloyl catechins, which is comparable to the level in human blood plasma after green tea consumption, significantly increased the bending stiffness of the membranes by a factor of more than 60, while those without the galloyl moiety had no detectable influence. Atomic force microscopy and circular dichroism spectroscopy suggest that the membrane stiffening is mainly attributed to the adsorption of galloyl catechin aggregates to the membrane surfaces. These results contribute to our understanding of the physical and thus the generic functions of green tea catechins in therapeutics, such as cancer prevention.

Yuji Higaki,Benjamin Fröhlich, Akihisa Yamamoto, Ryo Murakami,Makoto Kaneko, *Atsushi Takahara, and *Motomu Tanaka,
Ion-specific modulation of interfacial interaction potentials between solid substrates and cell-sized particles mediated via zwitterionic, super-hydrophilic poly(sulfobetaine) brushes,
The Journal of Physical Chemistry B 121, 1396−1404 (2017).

[Summary] Zwitterionic polymer brushes draw increasing
attention not only because of their superhydrophilic, self-
cleaning capability but also due to their excellent antifouling
capacity. We investigated the ion-specific modulation of the
interfacial interaction potential via densely packed, uniform
poly(sulfobetaine) brushes. The vertical Brownian motion of a
cell-sized latex particle was monitored by microinterferometry,
yielding the effective interfacial interaction potentials V(Δh)
and the autocorrelation function of height fluctuation. The
potential curvature V′′(Δh) exhibited a monotonic increase
according to the increase in monovalent salt concentrations,
implying the sharpening of the potential confinement. An
opposite tendency was observed in CaCl2 solutions, suggesting that the ion specific modulation cannot be explained by the classical Hofmeister series. When the particle fluctuation was monitored in the presence of free sulfobetaine molecules, the increase in [sulfobetaine] resulted in a distinct increase in hydrodynamic friction. This was never observed in all the other salt solutions, suggesting the interference of zwitterionic pairing of sulfobetaine side chains by the intercalation of sulfobetaine molecules into the brush layer. Furthermore, poly(sulfobetaine) brushes exhibited a very low V′′(Δh) and hydrodynamic friction to human erythrocytes, which seems to explain the excellent blood repellency of zwitterionic polymer materials.

Viktoria Frank, Stefan Kaufmann, Rebecca Wright, Patrick Horn, Hiroshi Yoshikawa, Patrick Wuchter, Jeppe Madsen, Andrew Lewis, Steven P. Armes, Anthony D. Ho, and *Motomu Tanaka,
Frequent mechanical stress suppresses proliferation of mesenchymal stem cells from human bone marrow without loss of multipotency,
Scientific Reports 6, 24264 (2016).

[Summary] Mounting evidence indicated that human mesenchymal stem cells (hMSCs) are responsive not only to biochemical but also to physical cues, such as substrate topography and stiffness. To simulate the dynamic structures of extracellular environments of the marrow in vivo, we designed a novel surrogate substrate for marrow derived hMSCs based on physically cross-linked hydrogels whose elasticity can be adopted dynamically by chemical stimuli. Under frequent mechanical stress, hMSCs grown on our hydrogel substrates maintain the expression of STRO-1 over 20 d, irrespective of the substrate elasticity. On exposure to the corresponding induction media, these cultured hMSCs can undergo adipogenesis and osteogenesis without requiring cell transfer onto other substrates. Moreover, we demonstrated that our surrogate substrate suppresses the proliferation of hMSCs by up to 90% without any loss of multiple lineage potential by changing the substrate elasticity every 2nd days. Such “dynamic in vitro niche” can be used not only for a better understanding of the role of dynamic mechanical stresses on the fate of hMSCs but also for the synchronized differentiation of adult stem cells to a specific lineage

Mariam Veschgini, F. Gebert, Nyamdorj Khangai, H. Ito, Ryo Suzuki, Thomas W. Holstein, Yasushi Mae, Takero Arai, and *Motomu Tanaka,
Tracking mechanical and morphological dynamics of regenerating Hydra tissue fragments using a two fingered micro-robotic hand,
Applied Physics Letters 108, 103702 (2016).

[Summary] Regeneration of a tissue fragment of freshwater polyp Hydra is accompanied by significant morphological fluctuations, suggesting the generation of active forces. In this study, we utilized a two fingered micro-robotic hand to gain insights into the mechanics of regenerating tissues. Taking advantage of a high force sensitivity (~1 nN) of our micro-hand, we non-invasively acquired the bulk elastic modulus of tissues by keeping the strain levels low (ε < 0.15). Moreover, by keeping the strain at a constant level, we monitored the stress relaxation of the Hydra tissue and determined both viscous modulus and elastic modulus simultaneously, following a simple Maxwell model. We further investigated the correlation between the frequency of force fluctuation and that of morpho- logical fluctuation by monitoring one “tweezed” tissue and the other “intact” tissue at the same time. The obtained results clearly indicated that the magnitude and periodicity of the changes in force and shape are directly correlated, confirming that our two fingered micro-hand can precisely quantify the mechanics of soft, dynamic tissue during the regeneration and development in a non- invasive manner.