CONCENTRATED PERFUSION MEDIUM

The invention relates to a serum-free cell culture perfusion medium comprising the medium components subgrouped into at least three separate aqueous concentrated feeds and a diluent, wherein the resulting serum-free cell culture perfusion medium is pH-adjusting to neutral pH upon mixing. Also provided is a method of preparing said serum-free cell culture perfusion medium. The invention further relates to methods of culturing mammalian cells or producing a protein of interest in perfusion culture using said serum-free cell culture perfusion medium that achieve high productivity at a low cell specific perfusion rate. The invention further relates to the use of the new and improved serum-free cell culture perfusion medium to control osmolality in a perfusion cell culture, wherein increasing osmolality results in an increase in total productivity and/or cell specific productivity by suppressing cell growth during cell culture, e.g., during production phase of perfusion cell culture. Suppression of cell growth particularly reduces or eliminates the need for wasteful cell bleed.