Master cell bank, MCB

For vaccines the starting material problem was addressed early, and methods were developed to control the identity and purity of the starting material. These studies often were completed with the aid of, and in the laboratories of, scientists at CBER with the conditions mutually agreed upon at the time of approval. Specifically, the development of master cell bank (MCB) and manufacturers working cell bank (MWCB) concepts helped... 

Once the cell line is selected as a host for production, a cell bank system must be generated to guarantee the availability of an adequate source of equivalent cells to use through the product s lifetime in the market. Usually, the cell bank system consists of two levels a master cell bank (MCB) and a manufacturer s working cell bank (WCB). 

Arindam Bose (Pfizer Central Research) further discussed the ICH documents and presented a rationale for the recommended combination of test procedures and process clearance validations required to demonstrate that marketed biopharmaceuticals are free of adventitious agents. He showed that testing of Pre-Seed Stock (PSS), the Master Cell Bank (MCB), and the Working Cell Bank (WCB) is required to demonstrate that they are free from contamination by mycoplasma, bacteria, molds, and yeasts. In addition, viral clearance validation studies must be performed on scaled down versions of each chromatographic step and the viral inactivation/removal step employed in the product purification scheme. Finally, clearance studies must be conducted with a panel of relevant and model viruses (typically three to four) to establish that the purification scheme will indeed purge any viruses that may be inadvertently introduced during processing. 

Independent clones isolated by transfection of a given host strain by the same vector can differ in their expression capabilities. Such clonal variation has been observed in most expression systems currently in use, and therefore examination of several independent clones for the desired expression and fermentation characteristics is a routine part of protein yield optimization. However, clonal variation is an ongoing process in all cultures that are propagated and is therefore not eliminated once a pure strain has been isolated. Thus, the properties and genetic background of the production strains have to be monitored constantly. Master cell banks (MCBs) and master working cell banks (MWCBs) are prepared to ensure... 

A master cell bank (MCB) is set up which forms the first generation of these clones. They are stored in hundreds of vials under liquid nitrogen freezers (-150 °C or below) to preserve them indefinitely. From the MCB, a vial is taken and another generation of clones is produced, these constitute the working cell bank (WCB), and they too are maintained in liquid nitrogen freezers. Subsequently, a vial is taken from the WCB for each batch of production. This two-tier system of MCB and WCB can supply production needs indefinitely. For example, 200 vials each of the MCB and WCB for a production rate of 10 batches per year will last 4000 years. 

This has been issued to describe analysis of the expression construct in eukaryotic and prokaryotic cells used for the production of r-DNA-derived protein products [29]. Both the expression construct and the purified final recombinant protein should be characterized. It should thereby be verified that the correct coding sequence has been incorporated and maintained during culture. A master cell bank (MCB) and a working cell bank (WCB) should be considered. Nucleic acid analyses, PCR-based assays and DNA-sequencing are methods to be used. A consistent quality of the final product should be guaranteed. 

Currently, most RTFs and mAbs are expressed in rodent, bacterial or yeast cell cultures (see Part IV, Chapter 13). A Master Cell Bank (MCB) should be estabbshed and tested for authenticity and freedom from contamination [5, 8, 11] (see also Part IV, Chapter 4). A Working Cell Bank (WCB) is extremely useful to extend the lifetime of the MCB. 

Mast cell beta-tryptase 405 Master cell bank (MCB) 784, 1645 Master virus bank (MVB) 157 Master working cell bank (MWCB) 746, 1129 Mastocytomas 1429... 

Master cell bank (MCB) Reversed phase HPLC (RP-HPLC) ... 

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