What are the special considerations for mammalian cell bioreactor design?

Mammalian cells require gentle conditions due to lack of cell wall. Key considerations include: low shear stress (use marine impellers or pitched-blade turbines, limit tip speed <1.5-2 m/s), surface aeration or microsparging to minimize bubble damage, CO2 removal systems (sweep gas in headspace), temperature control at 37C with precise uniformity, pH control avoiding direct acid/base contact with cells (use CO2 for acid addition), and longer batch times (2-3 weeks) requiring robust sterility and stability. Single-use systems are common. Perfusion bioreactors use cell retention devices (ATF, TFF, settlers). Scale-up prioritizes oxygen transfer while maintaining shear limits. Dead zones must be minimized for homogeneous cell suspension.