Cell banking is a process used in biotechnology and pharmaceutical industries to store and preserve cells for future use in research, development, and manufacturing of biopharmaceutical products. The primary purpose of cell banking is to ensure a consistent supply of cells with the desired genetic properties and to reduce the risk of contamination or genetic drift in cell lines used for producing biological products, such as recombinant proteins, monoclonal antibodies, or gene therapies.
There are two main types of cell banks:
- Master Cell Bank (MCB): The MCB is a collection of frozen vials of cells derived from a single cell culture, which has been extensively tested for identity, purity, and stability. The MCB serves as the primary source of cells for all subsequent production runs and as a reference for the genetic and phenotypic properties of the cell line. The MCB is carefully characterized and documented to ensure its consistency and quality.
- Working Cell Bank (WCB): The WCB is derived from a single vial of the MCB and is used for routine production purposes. The WCB undergoes additional testing to confirm its identity, purity, and stability. Once the WCB is established and tested, it is used for the manufacturing of the biopharmaceutical product. When the WCB is depleted, a new WCB is created from the MCB, ensuring a consistent supply of cells for production.
Cell banking involves several critical steps, including:
- Cell line selection: A suitable cell line is chosen based on the desired application, such as the production of a specific protein or the study of a particular disease model. Commonly used cell lines include mammalian cells (e.g., Chinese hamster ovary (CHO) cells, human embryonic kidney (HEK) 293 cells), insect cells, and bacterial cells.
- Cell culture expansion: The selected cell line is expanded in a controlled environment, such as a bioreactor or cell culture flask, to generate a sufficient number of cells for banking.
- Quality control testing: The cell line is tested for identity, purity, stability, and other critical quality attributes to ensure that it meets the required standards for biopharmaceutical manufacturing.
- Cryopreservation: The cells are mixed with a cryoprotective agent, such as dimethyl sulfoxide (DMSO), and aliquoted into individual vials. The vials are then frozen and stored at ultra-low temperatures (usually -135°C to -196°C) to maintain their viability and genetic stability over long periods.
- Storage and inventory management: The frozen vials of cells are stored in a controlled environment, such as a liquid nitrogen storage tank, and tracked using a comprehensive inventory management system.
- Thawing and recovery: When needed, the frozen vials of cells are carefully thawed, and the cells are revived and expanded for use in research, development, or manufacturing processes.
Cell banking is an essential component of biopharmaceutical manufacturing, ensuring a consistent supply of high-quality cells for the production of biological products and reducing the risk of contamination or genetic drift that could compromise product quality and safety.