Working cell banks (WCB’s) are commonly applied to initiate cell culture manufacturing campaigns for production of recombinant or therapeutic proteins. These campaigns typically begin with inoculation of cells previously cryopreserved in cryovials. While cryovials are typically used in the development of WCB’s and initiation of manufacturing campaigns, they are not optimal for the growing demands of commercial production.
Cryovials are small and filling/removal is performed through an open screw cap. This process results in manual operations and the use of many culture vessels, resulting in the risk of contamination and potential campaign-to-campaign variability. Single-use bags have been investigated more recently as a possible solution to minimize open handling steps and to shorten seed train scale-up. Bags offer larger storage volumes, but also come assembled with thermoplastic tubing for sterile connections. Wide-spread adoption of single-use bags for WCB applications has not been observed to this point as currently available tubing and connections can’t hold up to the demands when stored/transported at frozen or cryogenic (-196 °C) temperatures.
In an effort to overcome these challenges, novel thermoplastic tubing (FP-FLEX) was developed to balance both the flexibility and robustness demands of cryogenic storage and tube welding characteristics necessary for sterile closed-system processing. FP-FLEX™ tubing has been developed and shown herein to meet the critical processing requirements for WCB’s. Validation studies support that the new Freeze-Pak™ cryogenic storage containers with FP-FLEX™ tubing can be frozen and maintained at cryogenic temperatures and subsequently thawed and sterile welded to other thermoplastic tubing including the commonly used C-Flex®. The Freeze-Pak™ bag with FP-FLEX™ tubing represent a closed-system solution enabling frozen storage, sterile connection and ultimately reduced scale-up time for therapeutic production.