Cell culture inoculums expansion

Unit operations for biological products obtained from fermentation or cell culture can largely be subdivided into four parts medium preparation, inoculums expansion, bioreactor, and harvest operations. 

The use of perfusion bioreactors, in which the medium is pumped through the culture vessel, has also been reported (Oh et al., 2005) for the expansion of mouse ESC lines on Petriperm (a Petri dish with a gas-permeable base). The cell densities obtained were 64-fold greater compared to Petri dish controls which only originate a nine-fold increase compared to the initial inoculum, over 6 days. The mESCs that were expanded retained pluripotency markers, had the ability to form derivatives of the three embryonic germ layers in teratomas, and maintained karyotypic stability. Perfusion cultures with cell retention ensure homogeneity of nutrient supplementation, inhibition of waste accumulation, and improved process reproducibility (Thomson, 2007). However, these cultures are still at a small-scale. 

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