Continuous production of tissue plasminogen activator (t-PA) by human embryonic lung diploid fibroblast, IMR-90 cells, using a ceramic bed reactor

Abstract

Ceramic pieces composed of 99.5% Al2O3, 3 to 6 mm long, were found to be a good matrix for growth of the human embryonic lung diploid fibroblast, IMR-90 cells. The tissue plasminogen activator (t-PA) was secreted in DME medium containing proteose peptone as a t-PA inducer. In addition, production of t-PA was enhanced by increasing extracellular CaCl2, from 3.6 to 5.4 mM. In order to eliminate negative feed-back control caused by t-PA produced and thus raise productivity, perfusion cultivation was performed using a ceramic-packed bed column, with a recirculating vessel. The recirculating vessel was used to mix fresh medium with spent medium, and to control dissolved oxygen concentrations in the extracellular environment by stirring. In continuous production using the packed bed column with 2 kg of ceramics (phi = H = 150 mm), increasing dilution rate to 0.5 day-1 could reduce product inhibition at 3-4 x 10(5) cells/ml. Cellular productivity of 560 IU/10(6) cells/day was obtained over 40 days and corresponded to the volumetric productivity of 183 IU/ml/day.

Cell growth on electrospun nanofiber mats from polyacrylonitrile (PAN) blends

“…As mentioned earlier, Ca 2+ and Mg 2+ are cofactors for many attachment proteins and also for GAGs (34)(35)(36)(37)(38)(39). Therefore, the Ca 2+ concentration in media is often reduced to decrease adherence of cells cultured in suspension mode, or increased to culture anchorage-dependent cells on microcarrier beads (40). However, in addition to these two, more or less every other cation can modify the normally negatively charged culture surface.…”

Oxygen supply for CHO cells immobilized on a packed-bed of Fibra-Cel® disks

“…In situations where oxygen supply was insufficient, decreased culture viability, reduced metabolic activity, and finally a decreased productivity were observed (Kawakubo et al, 1994;Kurosawa et al, 2000;Ong et al, 1994;Racher et al, 1990;Yanagi et al, 1992). On the other hand, when oxygen supply was well controlled, significant improvements of PBR efficiency have been observed (Flendrig et al, 1997;Mitsuda et al, 1991;Racher and Griffiths, 1993;Wang et al, 1992). So, there is a need to develop a model that predicts how the oxygen concentration evolves at each point of a PBR.…”