Cell Culture Expansion in Fully Closed Erlenmeyer Shake Flasks Outside the Biosafety Cabinet

Expansion of suspension cell culture from cell bank to bioreactor is performed through passages of successively larger Erlenmeyer shake flasks. A traditional cap must be unscrewed for each fluid transfer. Risk of contamination is mitigated by performing these fluid transfers in a biosafety cabinet (BSC) or laminar flow hood. Work in a BSC is not preferred because of high maintenance and operating costs, intensive cleaning and decontamination procedures, and the inconvenience of performing operations in the BSC. Despite the use of a BSC, cultures are split to create back up flasks to be used in case of a contamination. Cell expansion can be improved by meeting the following objectives:

Problem Statement

Cellular respiration consumes O and produces CO₂ as a byproduct. Cultures with high CO₂ levels become acidic and impair cell viability. Improper O₂ levels can slow or stunt cell growth. Traditional Erlenmeyer flasks have a filter membrane embedded in the cap. The arrangement allows for unrestricted air flow across the entire filter surface but
leaves no room for integral tubing for aseptic fluid transfers. Flasks must be handled in a BSC and caps must be removed or exchanged. Bottle closures with integral tubing
enable aseptic fluid transfer. Air exchange is restricted at the hose barb on the filter housing. This small orifice limits the volume of air available to move into the culture, stunting cell growth.

Sartorius’s Solution

The manufacturing process of the patented MYCAP^® bottle closure is an enabling technology. Components are inserted into preformed holes. Silicone elastomer is dispensed into the cap to hermetically seal the installed components in place and to create the secure bottle closure.

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