Hiroshi Kimura

The University of Tokyo, Tōkyō, Japan

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Publications (25)57.65 Total impact

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    ABSTRACT: Parylene-C (diX C) has been used as a surface coating material with many biological applications; diX AM, a member of the diX C parylene family, retains biocompatible features. Previously, it has been reported that diX AM shows high cell adhesiveness; however, the effect of diX AM on the function of cells remains unknown. In this study, we investigated cell morphology and gene expression in human hepatocellular carcinoma (HepG2) cells cultured on diX AM. Our results show that HepG2 cells adhered to the surface of diX AM, and retained morphology similar to that of the cells cultured on collagen-coated surfaces. Furthermore, microarray analysis has revealed that the expression of CYP1A1 and CYP1A2 was highly induced in HepG2 cells cultured on diX AM without any additional factors. Moreover, CYP1 enzymatic activity measured by ethoxyresorufin-O-dealkylase (EROD) assay corresponded with the induction of gene expression. These results indicate a novel effect of diX AM on HepG2 cell function for the first time and diX AM could be used as non-animal-derived material for cell culture. Copyright © 2014 Elsevier B.V. All rights reserved.
    Materials Science and Engineering C 01/2015; 46:190–194. DOI:10.1016/j.msec.2014.10.030 · 2.74 Impact Factor
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    ABSTRACT: Testing of drug effects and cytotoxicity by using cultured cells has been widely performed as an alternative to animal testing. However, the estimation of pharmacokinetics by conventional cell-based assay methods is difficult because of the inability to evaluate multiorgan effects. An important challenge in the field is to mimic the organ-to-organ network in the human body by using a microfluidic network connecting small-scale tissues based on recently emerging MicroTAS (Micro Total Analysis Systems) technology for prediction of pharmacokinetics. Here, we describe an on-chip small intestine-liver coupled model for pharmacokinetic studies. To construct an in vitro pharmacokinetic model that appropriately models in vivo conditions, physiological parameters such as the structure of internal circulation, volume ratios of each organ, and blood flow ratio of the portal vein to the hepatic artery were mimicked using microfluidic networks. To demonstrate interactions between organs in vitro in pharmacokinetic studies, Caco-2, HepG2, and A549 cell cultures were used as organ models of the small intestine, liver, and lung, respectively, and connected to each other through a microporous membrane and microchannels to prepare a simple model of a physiological organ-to-organ network. The on-chip organ model assay using three types of substrate-epirubicine (EPI), irinotecan (CPT-11), and cyclophosphamide (CPA)-were conducted to model the effects of orally administered or biologically active anticancer drugs. The result suggested that the device can replicate physiological phenomena such as activity of the anticancer drugs on the target cells. This microfluidic device can thus be used as an in vitro organ model to predict the pharmacokinetics of drugs in the human body and may thus provide not only an alternative to animal testing but also a method of obtaining parameters for in silico models of physiologically based pharmacokinetics.
    Journal of the Association for Laboratory Automation 11/2014; 20(3). DOI:10.1177/2211068214557812 · 1.50 Impact Factor
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    ABSTRACT: Spherical three-dimensional (3D) cellular aggregates are valuable for various applications such as regenerative medicine or cell-based assays due to their stable and high functionality. However, previous methods to form aggregates have shown drawbacks, being labor-intensive, showing low productivity per unit area or volume and difficulty to form homogeneous aggregates. We proposed a novel strategy based on oxygen-permeable polydimethylsiloxane (PDMS) honeycomb microwell sheets, which can theoretically supply about 80 times as much oxygen as conventional polystyrene culture dishes, to produce recoverable aggregates in controllable sizes using mouse insulinoma cells (MIN6-m9). In 48 hours of culture, the PDMS sheets produced aggregates whose diameters were strictly controlled (⋍32, 60, 90, 150 and 280 mm) even at an inoculum density eight times higher (8.0×105 cells/cm2) than that of normal confluent monolayers (1.0×105 cells/cm2). Measurement of the oxygen tension near the cell layer and glucose/lactate analysis clearly showed that cells exhibit aerobic respiration on the PDMS-based culture system. Glucose-responsive insulin secretion of the recovered aggregates showed that the aggregates around 90 mm in diameter secreted the largest amounts of insulin. This confirmed the advantages of 3D cellular organization and the existence of a suitable aggregate size, above which excess organization leads to a decreased metabolic response. These results demonstrated that this microwell-based PDMS culture system provides a promising method to form size-regulated and better functioning 3D cellular aggregates of various kinds of cells with a high yield per surface area. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 2013
    Biotechnology Progress 01/2014; 30(1). DOI:10.1002/btpr.1837 · 1.88 Impact Factor
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    ABSTRACT: Developmental engineering is a potential option for neo-organogenesis of complex organs such as the kidney. The application of this principle requires the ability to construct a tubular structure from dispersed renal progenitor cells with defined size and geometry. In this present study we report the generation of tubular structures from dispersed ureteric bud cells in vitro by using a micropatterned gel. Dispersed CMUB-1 cells, a mouse ureteric bud-derived cell line, or mIMCD cells, a mouse collecting duct-derived cell line, were suspended in collagen I and seeded into an agarose-based micropatterned gel. We found that within 24-36 h of incubation, the cells developed a tubular structure that conformed to the geometry of the micropattern of the gel. The lumen formation of the tubular structure was confirmed by immunohistochemical staining and observed by confocal microscopy. We found that higher concentrations of collagen I negatively influenced the efficiency of tubular formation. Tubule formation in CMUB-1, but not mIMCD, cells was positively influenced by the addition of aldosterone (10, 50 and 200 µg/ml), FGF (50 and 100 µg/ml) and fibronectin (10 and 50 µg/ml) to the growth medium. We further demonstrated the functionality of the generated tubes by in vitro budding, which was induced by growth factors, such as glial cell-derived neurotrophic factor (GDNF) or fibroblast growth factor 7 (FGF7), in the presence of beads soaked with the activin A inhibitor follistatin. Our current study thus demonstrates the possibility of constructing a functional tubular structure from dispersed ureteric bud cells in vitro in a controlled manner. Copyright © 2014 John Wiley & Sons, Ltd.
    Journal of Tissue Engineering and Regenerative Medicine 01/2014; DOI:10.1002/term.1871 · 4.43 Impact Factor
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    ABSTRACT: We recently developed a polydimethylsiloxane (PDMS)-based three-compartment microfluidic cocultivation device enabling real-time interactions of different cell populations as an advanced physiologically-relevant cell-based assay. This device had valves and small magnetic stirrer-based internal pumps for easy and flexible perfusion operations. In this study, we applied this device for the evaluation of Irinotecan (CPT-11) toxicity to the lung, because it is detoxified by the liver and accumulated in the fat in humans. We successfully cultured representative three different tissue model cells in each compartment under the individual culture conditions and also in entire perfusion. Growth inhibition of rat lung epithelial cell line L-2, was measured when administered with 50 μM CPT-11 under various cocultivation conditions with respect to the presences and absence of primary rat hepatocytes (liver tissue model) and adipocyte-like cells (fat tissue model) induced from a mouse fibroblast cell line, 3T3-L1. Although CPT-11 showed moderate toxicity to the pure culture of L-2 cells in the device after 72 h of perfusion culture, this was lowered mainly in the presence of the liver tissue. Inhibition of the L-2 cell growth agreed with the area under curve (AUC) values obtained from fluorescent image-based analyses in each compartment. These results demonstrate that developed simple and flexible microfluidic cocultivation device, with appropriate image-based analyses, can be used in evaluating toxicokinetic behaviors of drug candidates in systemic levels.
    Journal of Bioscience and Bioengineering 12/2013; 117(6). DOI:10.1016/j.jbiosc.2013.11.019 · 1.79 Impact Factor
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    ABSTRACT: Despite the fact that cells in vivo are largely affected by the spatial heterogeneity in their surroundings, in vitro experimental procedures for stem cell differentiation have been relying on spatially uniform culture environments so far. Here, we present a method to form spatiotemporally non-uniform culture environments for stem cell differentiation using a membrane-based microfluidic device. By adopting a porous membrane with relatively large pores, patterned delivery of soluble factors is maintained stably over a period of time long enough for cell differentiation. We report that spatial patterns of mouse induced pluripotent stem cells (miPSCs) differentiation can be controlled by the present method. Furthermore, it is shown that the cell fate decision of miPSCs is determined by time-dependent switching of the delivery pattern. The present technique could be of relevance to the detailed analyses of the characteristics of stem cell differentiation in time and space, opening up a new insight into regenerative biology.
    Lab on a Chip 09/2012; 12(21):4508-15. DOI:10.1039/c2lc40268h · 5.75 Impact Factor
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    ABSTRACT: Cell-secreted soluble factor signaling in a diffusion dominant microenvironment plays an important role on early stage differentiation of pluripotent stem cells invivo. In this study, we utilized a membrane-based two-chambered microbioreactor (MB) to differentiate mouse embryonic stem cells (mESCs) in a diffusion dominant microenvironment of the top chamber while providing enough nutrient through the bottom chamber. Speculating that accumulated FGF4 in the small top chamber will augment neuronal differentiation in the MB culture, we first differentiated mESCs for 8 days by using a chemically optimized culture medium for neuronal induction. However, comparison of cellular morphology and expression of neuronal markers in the MB with that in the 6-well plate (6WP) indicated relatively lower neuronal differentiation in the MB culture. Therefore, to investigate whether microenvironment in the MB facilitates non-neuronal differentiation, we differentiated mESCs for 8 days by using chemically defined basal medium. In this case, differentiated cell morphology differed markedly between the MB and 6WP cultures: epithelial sheet-like morphology in the MB, whereas rosette morphology in the 6WP. Expression of markers from the three germ layers indicated lower neuronal but higher meso- and endo-dermal differentiation of mESCs in the MB than the 6WP culture. Moreover, among various cell-secreted soluble factors, BMP4 expression was remarkably upregulated in the MB culture. Inhibition of BMP4 signaling demonstrated that enhanced effect of upregulated BMP4 was responsible for the prominent meso- and endo-dermal differentiation in the MB. However, in the 6WP, downregulated BMP4 had a minimal influence on the differentiation behavior. Our study demonstrated utilization of a microbioreactor to modulate the effect of cell-secreted soluble factors by autoregulation and thereby inducing alternative self-capability of mESCs. Understanding and implementation of autoregulation of soluble factors similar to this study will lead to the development of robust culture systems to control ESC behavior.
    Biomicrofluidics 03/2012; 6(1):14117-1411713. DOI:10.1063/1.3693590 · 3.77 Impact Factor
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    ABSTRACT: In this study, we developed a well-of-the-well (WOW) system-based embryo culture plate with an oxygen sensing photoluminescent probe (OSPP). This system can incubate single embryos in an array of microwells and continuously and non-invasively monitor their morphology by microscopy and respiration metabolic activity based on the quenching of photoexcited platinum octaethylporphyrin by oxygen. Although the development rate to the blastocyst stage obtained in the WOW embryo culture plate with the OSPP was about 11% lower than that obtained with the conventional drop culture method because of the absence of paracrine effects due to the size of the microwells, the average cell number in the embryo at the blastocyst stage was not significantly different between the two culture systems. However, the present embryo culture plate enabled the selection and harvest of high quality blastocysts by monitoring both their morphology and their oxygen consumption rate, making it suitable for the high throughput evaluation of embryos.
    Sensors and Actuators B Chemical 02/2012; 162(1):278–283. DOI:10.1016/j.snb.2011.12.078 · 3.84 Impact Factor
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    ABSTRACT: Coupled cell-free transcription-translation (CFTT) of green fluorescent protein (GFP) has been applied as a reporter system to microfluidic chip-related technologies. In polymerase chain reaction (PCR)-based biomolecular logic gate system, in which addition of primer set and amplification of PCR product represent input and output signal respectively, GFP gene was inserted in the template DNA, which was then amplified, transcribed and translated to GFP. The green fluorescence reported as if the amplification has occurred or not, that is, the fluorescence reports positive output signal. CFTT of GFP was also adopted to evaluate on-chip capillary electrophoresis (CE)-based DNA fractionation, which was developed to isolate single DNA species from reaction mixture of DNA ligase-catalyzed DNA-assembly. As a model system, GFP gene was inserted in the target DNA fragment. The collected fraction was amplified with PCR and subjected to a CFTT system, and green fluorescence was observed showing that the fractionation was successful. These results showed that CFTT of GFP is a useful tool to verify, estimate, and monitor microfluidic chip-related technologies in which cell-free protein synthesis is involved.
    Frontiers in Bioscience 01/2012; 17:1931-9. · 4.25 Impact Factor
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    ABSTRACT: This paper describes a method for the selective retrieval of microparticles using bubbles generated by electrolysis. Microparticles (polystyrene beads, mouse embryos, and cell spheroids) were arrayed in microchambers fabricated in SU-8 on the surface of an electrode consisting of indium tin oxide (ITO) patterned on glass. Bubbles were selectively generated in a target microchamber by applying a voltage to electrodes positioned in the microchamber. As a result, we successfully retrieved microparticles (100μm in diameter) positioned in the microchambers. This method is gentle enough to maintain cellular viability, and therefore, it will be a powerful tool for the quantitative analysis of cells in an arrayed system.
    Sensors and Actuators B Chemical 11/2011; 159(1):229-233. DOI:10.1016/j.snb.2011.06.077 · 3.84 Impact Factor
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    ABSTRACT: In this study, we propose a microfluidic cell culture device mimicking the microscopic structure in liver tissue called hepatic cords. The cell culture area of the device was designed to align hepatocytes in two lines in a similar way to hepatic cords. Thanks to the structural design together with a cell seeding procedure, rat primary hepatocytes were successfully aligned in two lines and cultured under perfusion condition. It is shown that aligned hepatocytes gradually self-organize and form bile canaliculi along the hepatic cord-like structure. The present technique to culture hepatocytes with functional bile canaliculi could be used as an alternative to animal testing in the field of drug discovery and toxicological studies, and also be beneficial to tissue engineering applications.
    Biomicrofluidics 06/2011; 5(2):22212. DOI:10.1063/1.3580753 · 3.77 Impact Factor
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    ABSTRACT: Pluripotent stem cells are under the influence of soluble factors in a diffusion dominant in vivo microenvironment. In order to investigate the effects of secreted soluble factors on embryonic stem cell (ESC) behavior in a diffusion dominant microenvironment, we cultured mouse ESCs (mESCs) in a membrane-based two-chambered micro-bioreactor (MB). To avoid disturbing the cellular environment in the top chamber of the MB, only the culture medium of the bottom chamber was exchanged. Cell growth in the MB after 5 days of culture was similar to that in conventional 6-well plate (6-WP) and membrane-based Transwell insert (TW) cultures, indicating adequate nutrient supply in the MB. However, the cells retained higher expression of pluripotency markers (Oct4, Sox2 and Rex1) and secreted soluble factors (FGF4 and BMP4) in the MB. Inhibition of FGF4 activity in the MB and TW resulted in a similar cellular response. However, in contrast to the TW, inhibition of BMP4 activity revealed that autocrine action of the upregulated BMP4, which acted cooperatively with leukemia inhibitory factor (LIF), upregulated the pluripotency markers expression in the MB culture. We propose that BMP4 accumulated in the diffusion dominant microenvironment of the MB upregulated its own expression by a positive feedback mechanism-in contrast to the macro-scale culture systems-thereby enhancing the pluripotency of mESCs. The micro-scale culture platform developed in this study enables the investigation of the effects of soluble factors on ESCs in a diffusion dominant microenvironment, and is expected to be used to modulate the ESC fate choices.
    Biomedical Microdevices 12/2010; 12(6):1097-105. DOI:10.1007/s10544-010-9464-8 · 2.77 Impact Factor
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    ABSTRACT: On-chip Glucose Sensor for Online Measurement of Cell Activities
    IEEJ Transactions on Sensors and Micromachines 01/2010; 130:476-483. DOI:10.1541/ieejsmas.130.476
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    ABSTRACT: In vitro culture (IVC) of the mammalian embryo is an essential technique in reproductive technology and other related life science disciplines. Although embryos are usually cultured in groups, a single embryo culture has been highly desired for IVC to investigate developmental processes. In this study, we proposed and developed the first single embryo coculture device, which allows making an array of a single embryo coculture with endometrial cells by controlling the culture environment in a microfluidic device. To realize this concept, we investigated three key issues: selection of a culture medium for the embryo coculture with endometrial cells using a mouse embryo and endometrial cells, evaluation of an on-microporous-membrane coculture of endometrial cells and an embryo to control the polarization of endometrial cells on the membrane, and evaluation of the coculture of endometrial cells and the embryo in the microfluidic device. We successfully obtained an array of a single coculture of embryo with endometrial cells in a microfluidic device. This concept will open and enhance the management of an individual embryo for assisted reproductive technology, livestock breeding, and fundamental stage research by further development.
    IEEE transactions on nanobioscience 12/2009; 8(4):318-24. DOI:10.1109/TNB.2009.2035275 · 1.77 Impact Factor
  • Journal of Bioscience and Bioengineering 11/2009; 108. DOI:10.1016/j.jbiosc.2009.08.432 · 1.79 Impact Factor
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    ABSTRACT: We developed a chip-based coculture system for cytotoxicity test, as our continuous effort to develop a multi-functional micro culture device realized by integration of fluidic control. The culture zone in the device was divided into two compartments separated by a microporous membrane through which substances in culture medium can freely come-and-go to induce the mutual interactions between the cells cultured at each compartment. In this work, it was examined that 1) coculture and 2) cytotoxicity model through oral intake, using Caco-2 and Hep G2 cell as a model cell of small intestine and liver respectively. As a result of test 1), Hep G2 cells cocultured with Caco-2 show same albumin secretion activity as the one not cocultured with Caco-2 cells. As a result of test 2), The cytotoxicity of caffeine and paraquat on Hep G2 cells was successfully measured with and without association of a selective chemical barrier function of Caco-2 cells.
    IEEJ Transactions on Sensors and Micromachines 01/2009; 129(8):252-258. DOI:10.1541/ieejsmas.129.252
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    ABSTRACT: Embryo handling is an extremely important fundamental technique in reproductive technology and other related life science discipline. The handling usually requires an artisanal operation that uses a glass-made capillary tube to suck in / out the embryo by applying external pressure with mouth or pipetting, to move it one to another environment and to redeliver into the womb. Because of the delicate operations, it is difficult to obtain quantitative result through the experiments. It is therefore an automatic embryo handling system has been highly desired to obtain stable quantitative results, and to reduce the stress for the operators. In this paper, we proposed and developed an automated embryo culture device, which can make an array of the embryos, culture them to be the blastocyst stage, and collect the blastocyst using the dynamic microarray format that we had studied previously. We preliminary examined the three functions of trapping, culture, and release using a mouse embryo as a sample. As a result, the mouse embryos are successfully trapped and released, whereas the efficiency of the in-device embryo culture was less comparable than the conventional dish culture. The culture stage still needs optimization for embryos, however the concept of embryo manipulation was proofed successfully.
    IEEJ Transactions on Sensors and Micromachines 01/2009; 129(8):245-251. DOI:10.1541/ieejsmas.129.245
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    ABSTRACT: Polymerase chain reaction-based biochemical logic gates were designed for AND, OR, NOT, and AND-NOT operations, whose output signal is reported by coupled cell-free transcription-translation of green fluorescent protein.
    Chemical Communications 09/2008; DOI:10.1039/b807039c · 6.72 Impact Factor
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    ABSTRACT: Conventional cell-based assays in life science and medical applications can be difficult to maintain functionally over long periods. Microfluidics is an emerging technology with potential to provide integrated environments for cell maintenance, continuous perfusion, and monitoring. In this study, we developed an integrated microfluidic device with on-chip pumping and detection functionalities. The microfluidic structure in the device is divided into two independent channels separated by a semipermeable membrane on which cells are inoculated and cultured. Perfusion and fluorescence measurements of culture media for each channel can be conducted by the on-chip pumping system and optical fiber detection system. Performance of the device was examined through long-term culture and monitoring of polarized transport activity of intestinal tissue models (Caco-2 cells). The cells could be cultured for more than two weeks, and monolayer transport of rhodamine 123 was successfully monitored by on-line fluorescent measurement. This device may have applications in toxicity testing and drug screening.
    Lab on a Chip 06/2008; 8(5):741-6. DOI:10.1039/b717091b · 5.75 Impact Factor

Publication Stats

143 Citations
57.65 Total Impact Points


  • 2007–2015
    • The University of Tokyo
      • Institute of Industrial Science
      Tōkyō, Japan
  • 2014
    • Tokai University
      Hiratuka, Kanagawa, Japan
  • 2012
    • Kitasato University
      • College of Liberal Arts and Sciences
      Edo, Tōkyō, Japan