Performance study of perfusion cultures for the production of single-chain urokinase-type plasminogen activator (scu-PA) in a 2.5 l spin-filter bioreactor

Abstract

A perfusion-control strategy based on cellular consumption rates of oxygen and glucose was established for the production of single-chain urokinase-type plasminogen activator (scu-PA). Employing this strategy, the influences of microcarrier types and the culture media on culture performances were evaluated. In the control perfusion culture, which used a solid microcarrier and a 1% fetal bovine serum (FBS) medium, viable cell density reached 3.1 x 10(7) cells ml(-1). However, formation of large, heterogeneous aggregates (500-1,000 mu m) resulted in a gradual decrease in viable cell density to less than 1.0 x 10(7) cells ml(-1). Accordingly, declines in the production of urokinase-type plasminogen activator (u-PA) and in the scu-PA portion of u-PA were observed. In the serum-free media, cell growth and u-PA production were suppressed 2-3 times, but were significantly enhanced when a porous microcarrier, Cultispheer G, was used. The cell-growth profile showed a continuous increase in cell density, reaching 5.1 x 10(7) cells ml(-1), and the production of u-PA remained stable throughout the culture (1586 +/- 247 IU ml(-1)). The values of all the parameters associated with cell growth and u-PA production were fairly comparable to or even higher than those in the control culture. Moreover, a 13% higher scu-PA portion of u-PA was observed in the serum-free culture, regardless of the microcarrier type, compared with scu-PA portion of u-PA in the control culture.