Upstream processing

The part of biomanufacturing that grows the cells and makes the product: thawing the cell bank, seed expansion and production culture in a bioreactor, up to harvest. Upstream choices, such as host cell line, medium, feeding strategy and culture duration, set the titer and the impurity and variant profile that downstream processing must then handle. Japanese documents use the loanword and a native term meaning 'upstream process' (上流工程). Avoid the abbreviation USP in English translations, where it clashes with the United States Pharmacopeia.