A membrane-based method for removal of toxic ammonia from mammalian-cell culture.

Many mammalian cells grown in culture excrete ammonia, which, when it accumulates, limits cell growth and reduces product synthesis. Common tactics for minimizing the effects of ammonia accumulation are uneconomical, requiring large quantities of media and incurring high capital costs. Solution-diffusion membranes were investigated for ammonia removal, and a supported-gas membrane was identified that could be used to remove ammonia rapidly to well below inhibitory levels. Medium treated using this membrane was reused to culture baby-hamster kidney cells, resulting in a cell growth rate that was essentially the same as that for cells grown in fresh medium.