Ku Youn Baik

Controlling the Growth and Differentiation of Human Mesenchymal Stem Cells by the Arrangement of Individual Carbon Nanotubes

Carbon nanotube (CNT) networks on solid substrates have recently drawn attention as a means to direct the growth and differentiation of stem cells. However, it is still not clear whether cells can recognize individual CNTs with a sub-2 nm diameter, and directional nanostructured substrates such as aligned CNT networks have not been utilized to control cell behaviors. Herein, we report that human mesenchymal stem cells (hMSCs) grown on CNT networks could recognize the arrangement of individual CNTs in the CNT networks, which allowed us to control the growth direction and differentiation of the hMSCs. We achieved the directional growth of hMSCs following the alignment direction of the individual CNTs. Furthermore, hMSCs on aligned CNT networks exhibited enhanced proliferation and osteogenic differentiation compared to those on randomly oriented CNT networks. As a plausible explanation for the enhanced proliferation and osteogenic differentiation, we proposed mechanotransduction pathways triggered by high cytoskeletal tension in the aligned hMSCs. Our findings provide new insights regarding the capability of cells to recognize nanostructures smaller than proteins and indicate their potential applications for regenerative tissue engineering.

Fibronectin–Carbon-Nanotube Hybrid Nanostructures for Controlled Cell Growth

Recently, carbon nanotube (CNT)-based devices have been extensively utilized for various cellular applications, including neural-signal amplifi cation, [ 1 , 2 ] cancer therapeutics, [ 3 ] and tissue engineering. [ 4 ] For those applications, it is often crucial to control the location and direction of cell growth on CNTs while mimicking an in-vivo-like cellular environment to retain in-vivo-like cellular activity. Several research groups have reported that bulk CNT substrates can support cell adhesion, growth, and differentiation. [ 5–8 ] CNT patterns were also reported to induce the selective growth of neurons and human mesenchymal stem cells (hMSCs). [ 9 , 10 ] However, the effects of CNTs on cells are still controversial and the underlying mechanism for selective cell adhesion and growth is still obscure. In this Communication, we report a study of the role of extracellular matrix (ECM) proteins, such as fi bronectin (FN), in CNT–cell interactions and propose FN–CNT hybrid nanostructures as an effi cient means for cell-growth control. In this work, we fi rst investigated the adhesion properties and conformational change of FNs on the CNTs via immunofl uorescence and force-spectroscopy study. FNs exhibited a strong affi nity to CNTs and maintained a high binding capability to biomolecules even after being adsorbed onto the CNTs. Moreover, the results of our force-spectroscopy-based protein-unfolding experiment confi rm that FNs maintained their native structures on the CNTs. FN–CNT hybrid nanostructures had a stronger affi nity to cells than conventional surfaces, such as FN-coated glass. Importantly, cells formed focal adhesion and grew selectively on the FN–CNT hybrid nanostructures, indicating that the selective growth of cells on

Universal Parameters for Carbon Nanotube Network-Based Sensors: Can Nanotube Sensors Be Reproducible?

Carbon nanotube (CNT) network-based sensors have been often considered unsuitable for practical applications due to their unpredictable characteristics. Herein, we report the study of universal parameters which can be used to characterize CNT network-based sensors and make their response predictable. A theoretical model is proposed to explain these parameters, and sensing experiments for mercury (Hg(2+)) and ammonium (NH(4)(+)) ions using CNT network-based sensors were performed to confirm the validity of our model.

Carbon Nanotube Monolayer Cues for Osteogenesis of Mesenchymal Stem Cells

Recent advances in nanotechnology present synthetic bio-inspired materials to create new controllable microenvironments for stem cell growth, which have allowed directed differentiation into specific lineages.[1,2] Carbon nanotubes (CNTs), one of the most extensively studied nanomaterials, can provide a favorable extracellular environment for intimate cell adhesion due to their similar dimension to collagen. It has been shown that CNTs support the attachment and growth of adult stem cells[3-6] and progenitor cells including osteoblasts and myoblasts.[7,8] In addition, surface-functionalized CNTs provide new opportunities in controlling cell growth. Surface functionalization improves the attachment of biomolecules, such as proteins, DNA, and aptamers, to CNTs.[9] Zanello et al. cultured osteoblasts on CNTs with various functional groups and showed reduced cell growth on positively charged CNTs.[10] Recent reports have shown that human mesenchymal stem cells (hMSCs) formed focal adhesions and grew well on single-walled CNTs (swCNTs).[5,6] However, the effect of naive swCNT substrates on the differentiation of stem cells has not been reported before. Herein, we report the osteogenic differentiation of hMSCs induced by swCNT monolayer cues without any chemical treatments. Interestingly, the surface treatment of swCNTs via oxygen plasma showed synergistic effects on the differentiation as well as the adhesion of hMSCs. The stress due to the enhanced cell spreading on swCNT layers was proposed as a possible explanation for the enhanced osteogenesis of hMSCs on the swCNT monolayers. Previous reports showed that the stress to stretch stem cells on microscale molecular patterns generated the tension on actin filaments, which eventually enhanced the osteogenesis.[11,12] Since our method relies on monolayer coating of swCNTs, it can be applied to a wide range of substrates including conventional scaffolds without any complicated fabrication processes.

Responses of Solid Tumor Cells in DMEM to Reactive Oxygen Species Generated by Non-Thermal Plasma and Chemically Induced ROS Systems

In this study, we assessed the role of different reactive oxygen species (ROS) generated by soft jet plasma and chemical-induced ROS systems with regard to cell death in T98G, A549, HEK293 and MRC5 cell lines. For a comparison with plasma, we generated superoxide anion (O2−), hydroxyl radical (HO·), and hydrogen peroxide (H2O2) with chemicals inside an in vitro cell culture. Our data revealed that plasma decreased the viability and intracellular ATP values of cells and increased the apoptotic population via a caspase activation mechanism. Plasma altered the mitochondrial membrane potential and eventually up-regulated the mRNA expression levels of BAX, BAK1 and H2AX gene but simultaneously down-regulated the levels of Bcl-2 in solid tumor cells. Moreover, a western blot analysis confirmed that plasma also altered phosphorylated ERK1/2/MAPK protein levels. At the same time, using ROS scavengers with plasma, we observed that scavengers of HO· (mannitol) and H2O2 (catalase and sodium pyruvate) attenuated the activity of plasma on cells to a large extent. In contrast, radicals generated by specific chemical systems enhanced cell death drastically in cancer as well as normal cell lines in a dose-dependent fashion but not specific with regard to the cell type as compared to plasma.

Acupuncture Meridian and Intravascular Bonghan Duct

Current anatomical theory does not recognize the existence of an extended floating threadlike structure inside the blood vessels. Nonetheless, this study developed a new method for observing such an intravascular threadlike structure. The key technique involves injecting acridineorange into the femoral vein to circulate along the blood vessels and stain the nuclei of the intravascular threads inside the blood vessels. In-situ observations were then made under a fluorescence stereomicroscope after saline-perfusion. Confocal microscope images revealed a distinctive characteristic pattern of nucleus distribution that was clearly distinguishable from fibrin, capillaries, small venules, arterioles, or lymph vessels. Accordingly, it is suggested that the identified intravascular threads are part of the Bonghans circulatory network that is distributed throughout the body, including inside the blood vessels.

Scanning probe microscopy study of microcells from the organ surface Bonghan corpuscle

Microcells from organ surface Bonghan corpuscles [B. H. Kim, J. Acad. Med. Sci. DPR Kor. 90, 1 (1963)] of mammals have been studied by using optical microscopy, transmission electron microscopy and immunohistochemistry. In order to further investigate their physical and electrical properties at better resolution, many different modes of scanning probe microscopy were used in this research. Their surface morphology was studied by topography imaging and error-signal imaging of atomic force microscopy and their mechanical properties were investigated by force modulation microscopy. Electrostatic force microscopy was also used for their electrical characterization.

Visualization of Bonghan Microcells by Electron and Atomic Force Microscopy

OBJECTIVES The origin of adult stem cells remains an open question. If they derive from embryos, it is difficult to determine the mechanism which interrupts their differentiation during tissue formation. In the 1960s, the Bonghan microcell was suggested as one possible, yet to be described, route of stem cell production, such that they have the potential to proliferate to produce normal cells. MATERIALS AND METHODS In this study, Bonghan microcells were isolated from Bonghan tissues on rat organ surfaces, and their detailed morphology examined by electron and atomic force microscopy. RESULTS The ultrastructure observed distinguished them from apoptotic bodies and other microorganisms, and their unique, possible proliferation feature, as protruding threads, was imaged by atomic force microscopy. CONCLUSIONS The unique threadlike structure of the Bonghan microcell is consistent with Prof. Kims observation in the first step of making a cell. Understanding of the functions of this threadlike structure may give a clue to understand the origin or the differentiation cue of adult stem cells.

Influence of Hydroxyl Group Position and Temperature on Thermophysical Properties of Tetraalkylammonium Hydroxide Ionic Liquids with Alcohols

In this work, we have explored the thermophysical properties of tetraalkylammonium hydroxide ionic liquids (ILs) such as tetrapropylammonium hydroxide (TPAH) and tetrabutylammonium hydroxide (TBAH) with isomers of butanol (1-butanol, 2-butanol and 2-methyl-2-propanol) within the temperature range 293.15–313.15 K, with interval of 5 K and over the varied concentration range of ILs. The molecular interactions between ILs and butanol isomers are essential for understanding the function of ILs in related measures and excess functions are sensitive probe for the molecular interactions. Therefore, we calculated the excess molar volume (VE) and the deviation in isentropic compressibility (Δκs) using the experimental values such as densities (ρ) and ultrasonic sound velocities (u) that are measured over the whole compositions range at five different temperatures (293.15, 298.15, 303.15, 308.15 and 313.15 K) and atmospheric pressure. These excess functions were adequately correlated by using the Redlich–Kister polynomial equation. It was observed that for all studied systems, the VE and Δκs values are negative for the whole composition range at 293.15 K. And, the excess function follows the sequence: 2-butanol>1-butanol>2-methyl-2-propanol, which reveals that (primary or secondary or tertiary) position of hydroxyl group influence the magnitude of interactions with ILs. The negative values of excess functions are contributions from the ion-dipole interaction, hydrogen bonding and packing efficiency between the ILs and butanol isomers. Hence, the position of hydroxyl group plays an important role in the interactions with ILs. The hydrogen bonding features between ILs and alcohols were analysed using molecular modelling program by using HyperChem 7.

Non-thermal plasma with 2-deoxy-D-glucose synergistically induces cell death by targeting glycolysis in blood cancer cells

In this study, we show the selective and efficient anti-cancer effects of plasma (at a low dose) when cell metabolic modifiers are also included. 2-deoxy-D-glucose (2-DG), a glycolytic inhibitor, was used with effective doses of non-thermal plasma, synergistically attenuating cell metabolic viability and inducing caspase-dependent and independent cell death. The combination treatment decreased the intracellular ATP and lactate production in various types of blood cancer cells in vitro. Taken together, our findings suggest that 2-DG enhances the efficacy and selectivity of plasma and induces the synergistic inhibition of cancer cell growth by targeting glycolysis and apoptosis. Specifically, this treatment strategy demonstrated an enhanced growth inhibitory effect of plasma in the presence of a metabolic modifier that was selective against cancer cells, not non-malignant cells. This is the first study to report the advantage of combining plasma with 2-DG to eradicate blood cancer cells. Finally, we conclude that 2-DG with non-thermal plasma may be used as a combination treatment against blood cancer cells.