Mammalian cells grown in culture excrete ammonium ion that accumulates in quantities that may limit cell growth and reduce product synthesis. The usual tactic for limiting the accumulation of ammonia is to replace the "spent" medium with fresh medium. Since medium replacement increases the use of expensive medium components, ammonium accumulation lowers cell and product yield on medium and increases production costs. An attractive strategy for nullifying the problems associated with ammonium ion excretion is to provide a continuous process for removing ammonium ion and maintaining it at a subinhibitory, steady-state concentration. In this proposal, Dr. Van Eikeren describes a membrane-based process for the selective and continuous removal of ammonium ions produced during mammalian cell culture. Preliminary technical and economic analyses suggest that the process proposed will be effective. A membrane-based process for ammonia removal, coupled to a fermenter would be valuable for growing mammalian cells for the purpose of manufacturing protein products.
