The development of master and working cell banks are done within the facility. Regulatory authorities recommend that production cell banks be stored in two or more widely separated areas within a production facility as well as at a distant site in order to avoid loss of the cell line. Dual-site storage of all cells is accomplished with on-site storage and off-site storage. Once your project is completed, any unused cells can be either returned to you or destroyed at your option.

When a cell line is to be used over many manufacturing cycles, a two-tiered cell banking system consisting of a master cell bank (MCB) and a working cell bank (WCB) is recommended. If not provided by the customer, a cell line is established from a single clone and this cell line is used to make-up the MCB. This MCB must be characterized and extensively tested for contaminants such as bacteria, fungi and mycoplasma. Most Cell Lines also require testing for viruses. Cells from the MCB are expanded to form the WCB, which is characterized for cell viability prior to use in the manufacturing process.