Tomoaki Kawai

Hokkaido University, Sapporo, Hokkaidō, Japan

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Publications (4)3.38 Total impact

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    ABSTRACT: Hepatocytes were cultured on a honeycomb-patterned polymer film (honeycomb film) formed by self-organization in order to investigate the influence of the honeycomb pattern on cell behavior. The changes in cell morphologies and actin filaments were observed by optical, fluorescence, and scanning electron microscopy. Hepatocytes were flattened, and the actin filaments appeared conspicuously in the spreading regions on a flat film. In contrast, the hepatocytes that were cultured on the honeycomb film were observed to form a spherical shape, and the actin filaments were localized inside the edge of the spheroid. The spheroids were observed within several hours after seeding on the honeycomb film; they were attached and the spheroid shape was maintained without any deformation. The spheroids expressed a higher level of liver specific function than the cell monolayers on the flat film. These results suggest that the honeycomb film is a suitable material for tissue engineering scaffolds and biomedical devices.
    Colloids and Surfaces A-physicochemical and Engineering Aspects - COLLOID SURFACE A. 01/2006; 284:464-469.
  • International Journal of Nanoscience 10/2002; 1(05n06):689-693.
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    ABSTRACT: Hepatocyte spheroids are expected to be the main component of the artificial liver bioreactor for their higher function. The preparation of hepatocyte spheroids, however, can require as many as 24 to 96 h. To reduce this time, we investigated a method employing a new technique of rat hepatocyte preparation and a dynamic culture. The modified Seglen's method for standard hepatocyte isolation was altered by elimination of ethyleneglycol bis(aminoethylether) tetraacetate from the first perfusate and calcium from the second perfusate. Isolated hepatocytes were cultured in a spinner flask by spinning at 120 rpm. The modified Seglen's method was used as a control. Cells obtained by the new method were more cohesive and formed a higher proportion of cell aggregates than control cells. In the spinning culture, hepatocytes had a tendency to aggregate and 80% of cells formed spheroids within 6 h of culturing. The mean size of spheroids was 68.5 +/- 18.5 microm. Confocal laser scanning microscopy revealed that individual spheroids contained approximately 30% of nonparenchymal cells over their surface. Using the new hepatocyte preparation method followed by a spinning culture, we were able to produce hepatocyte spheroids in as few as 6 h.
    Artificial Organs 07/2002; 26(6):497-505. · 1.96 Impact Factor
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    ABSTRACT: Mixed liver cell spheroids from rats consisting of hepatocytes and nonparenchymal cells lose three-dimensional structure and function when cultured on dishes. In order to maintain the configuration and function of the spheroids, we cultured them with collagen gel in various conditions, such as on the surface of collagen gel (group 2), between two collagen gel layers (group 3), and within collagen gel (group 4). Spheroids cultured on a standard collagen-coated dish were used as controls (group 1). Culture was continued for 10 days. Phase-contrast microscopy revealed that the spheroids of group 1 lost their spheroidal configuration and became a monolayer within 24 h. Group 2 spheroids also spread out to a monolayer, but thus occurred at 24 to 48h. In group 3, spheroid configuration was sustained until day 10, though slightly flattened. In group 4, the spheroid configuration was well maintained throughout the culture period. Urea synthesis of the spheroids cultured with collagen gel was significantly higher than in group 1 between days 1 and 3. Albumin synthesis of three experimental groups was also significantly higher than that of group 1. Although three experimental groups showed no difference in urea synthesis, albumin production by spheroids in groups 3 and 4 was better maintained than in group 2, even toward the end of the culture period. It is concluded that mixed liver-cell spheroid culture within collagen gels showed better maintenance of their configuration and function.
    Journal of Artificial Organs 4(4):331-335. · 1.41 Impact Factor