A seed train is the sequential series of cell culture expansion steps performed to grow a cell population from a Working Cell Bank (WCB) vial to a sufficient volume and cell density to inoculate a production bioreactor. It typically progresses through increasingly larger culture vessels — from shake flasks or tubes through benchtop bioreactors to pilot-scale bioreactors — under defined process parameters to ensure consistent cell quality, viability, and growth kinetics at each stage. The design and optimization of the seed train is a critical component of upstream process development, directly impacting production bioreactor performance, batch consistency, and manufacturing timelines in CDMO operations.
