PROTEIN ADSORPTION IN POLYSULFONE HOLLOW-FIBER BIOREACTORS USED FOR SERUM-FREE MAMMALIAN-CELL CULTURE

The recovery of serum-free medium proteins from polysulfone hollow fib er bioreactors (HFBRs) was investigated. More than 99% of the initial transferrin was adsorbed to the hydrophobic hollow fibers within 2 h o f HFBR operation. A methodology to minimize transferrin adsorption by pre-adsorption of bovine serum albumin (BSA) was developed. BSA adsorp tion on suspended cut fibers was virtually complete within 1 h. BSA-co ated fibers adsorbed only 5% of the transferrin within 10 days, wherea s uncoated cut fibers adsorbed more than 99% of the transferrin within 1 h. An improved HFBR startup procedure, using a BSA-coating step bef ore inoculation, resulted in substantially higher transferrin recovery . Additional factors influenced extracapillary space (ECS) transferrin concentrations. Pronounced downstream polarization of transferrin was observed in the ECS. In addition, the 30-kDa nominal molecular weight cutoff ultrafiltration membranes rapidly leaked transferrin from the ECS to the lumen. (C) 1993 John Wiley & Sons, Inc.