Kei Nishii

Production of rG-CSF by CHO cell in aggregate microbeads culture

Chinese Hamster ovary (CHO) cells which produce granulocyte colony stimulating factor (G-CSF) were cultivated in a spinner flask containing dextran microbeads of about 50 μm in average diameter. After inoculation, cell attachment to the microbeads and formation of the aggregate between cells and microbeads were observed. After 5 days cultivation, some of the aggregates of cells and microbeads became over 200 μm in diameter. One aggregate was composed of about fifteen or more microbeads. The exchange of culture medium was done by settling the aggregates. By the aggregate microbeads culture method, continuous cultivation of CHO cells and production of G-CSF were performed.

Propene polymerization by ansa-fluorenylamidodimethyltitanium activated with SiO2-supported modified methylalminoxane

SiO 2 -supported cocatalyst was prepared from trialkylaluminium-free modified methylaluminoxane. Propene polymerization was performed by [t-BuNSiMe 2 (Flu)]-TiMe 2 combined with the prepared cocatalyst in heptane. The supported system showed a comparable initial activity to the corresponding homogeneous system that conducts living polymerization of propene and gave the polymer with higher molecular weight and broader molecular weight distribution. Deactivation and chain transfer reaction however occurred in the supported system.

Aggregate Animal Cell Culture by Using Microbeads

A microcanier has been used for cultivating anchorage-dependent animal cells in a stirred vessel. Since animal cells grow on the surface of a microcarrier, cells are damaged due to shear stress around a microcarrier or collisions between microcarriers. These hydrodynamic detrimental effects have been removed by the ideas such as cultivation by using a microcarrier with porous internal structure and development a newly type of bioreactor so as to avoid the hydrodynamic detrimental effects. The hydrodynamic effect on cells in the suspended culture for an anchorage-independent cell is smaller than that in the microcarrier culture for an anchorage-dependent cell.