Master cell banks

Biotechnology feniientation/ cell culture Establishment of master cell bank and working cell bank Maintenance of working cell bank Cell culture and/or fermentation Isolation and purification Physical processing, and packaging... 

The cell bank s construction design is normally two tiered, consisting of a master cell bank and a working cell bank (Figure 5.6). The master cell bank is constructed first, directly from a culture of the newly constructed production cell line. It can consist of several hundred individually stored ampoules. 

Figure 5.6 The master cell bank/working cell bank system. For simplicity, each bank shown above contains only five ampoules. In reality, each bank would likely consist of several hundred ampoules. Working cell bank number 2 will be generated from master cell bank vial number 2 only when working cell bank number 1 is...

Cell Bank Controls for working and master cell banks... 

Master Cell Bank and Working Cell Bank Origin... 

Production is based on a validated seed-lot system using a host-vector combination that has been shown to be suitable to the satisfaction of the competent authority. The seed-lot system uses a master cell bank and a working cell bank derived from the master seed lot of the host-vector combination. A detailed description of cultivation, extraction and purification steps and a definition of the production batch shall be established. 

The master cell bank is a homogeneous suspension of the original cells already transformed by the expression vector containing the desired gene, distributed in equal volumes into individual containers for storage (e.g. in liquid nitrogen). In some cases it may be necessary to establish separate master cell banks for the expression vector and the host cells. 

Figure 4.9. Optimization of product yieid through sequential and systematic screening and selection of genetic construct and recombinant host cells that produce the highest yield and genetic stability. The schematically presented steps are required to develop a master cell-bank, and working stock for the production of biologically active recombinant proteins in pharmaceutical scale.

For drag substance and drug product, establishment of a new master cell bank or seed. 

Choose one of the clones from the final (100% efficiency) cloning as the master cell line, expand it in tissue culture and cryogenically preserve stocks of it as the master cell bank (at least 12 vials). 

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... 

Preparation and characterization of the clone master cell bank and working cell bank... 

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). 

LSBL MAP MCB NDA NIH PPC PTC QA QC RAP WCB WCP WHO large-scale biosafety level mouse antibody production master cell bank new drug application National Institutes of Health post-production cells points to consider quality assurance quality control rat antibody production working cell bank well-characterized product World Health Organization... 

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. 

Master seed microorganism and master cell bank Eitensive characterization at lowest and highest passage level... 

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... 

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