平板型高細胞密度バイオリアクターの流動特性と酸素代謝の評価(熱工学,内燃機関,動力など)  [in Japanese] Measurement of Flow Characteristics and Oxygen Metabolism of Plate Type Bioreactor for in vitro High-Density Cell Culture(Thermal Engineering)  [in Japanese]

Engineered tissue of digestive organ requires high cell density around 10^7〜10^9cells/mL. For the production of such a high cell density engineered tissue, namely a bioreactor, microstructured scaffold and the flow system supplying oxygen to the cells, should be designed systematically. For this purpose, the plate type hepatic bioreactor, which was optimally designed to support 10^8cells/mL cells, was produced to estimate the flow characteristics and oxygen mebolism. The microstructured scaffold which is composed of aligned square pillars, was designed to allow hepatocytes to attached on the surface of microstructures in cell density of 10^8cells/mL. The designed scaffold with microstructures (pillar hight: 109.6μm, channel: 33.1μm) was fabricated using PDMS. The flow resistance of fabricated scaffold was measured at flow rate from 0.46 to 2.0mL/sec. Thereafter, hepatoma cell line HepG 2 were cultured in the scaffold with open culture to compose bioreactor of high cell density around 9.7×10^7〜1.9×10^8cells/mL. Finally, the bioreactor was closed for perfusion cell-culture, which simulates in vivo circulation system. Oxygen concentration of inlet and outlet of the bioreactor in perfusion cell-culture were measured under the perfusion flow rate from 0.3 to 2.2mL/min. The result showed that there is a certain flow rate, under which the bioreactor consumes maximum oxygen. Nevertheless maximum cellular oxygen metabolic rate in the bioreactor is far lower than normal cellular metabolic rate. This trend explains the diffusion resistance on cellular surface and the detachment of cells from the surface of bioreactor at high flow rate.