Master seed cultures

Master seed cultures quality, documentation, suitability. 

As it is imperative that the plant-derived hiopharmaceutical product must be obtained repeatedly and on a consistent basis, a master cell culture bank, seed bank for transgenic plants, or virus seed stock for transient expression systems must be constantly maintained. Storage conditions must therefore he optimized to prevent contamination and ensure viability. Both transgene stability (e.g., reversion to wild type or sequence drift of plant virus expression vectors) and protein expression levels must be monitored in a representative plant of a given bank or stock to minimize any possible variation in expression levels that may affect safety and consistency of the hnal product. A program that monitors lot-to-lot consistency of the hiochemical and biological properties by comparing the product with appropriate in-house reference standards could he implemented as a fundamental component of product development. 

MASTER SEED LOT A culture of a micro-organism distributed from a single bulk into containers in a single operation in such a manner as to ensure uniformity, to prevent contamination and to ensure stability. A master seed lot in liquid form is usually stored at or below -70°C. A freeze-dried master seed lot is stored at a temperature known to ensure stability. 

WORKING SEED LOT A culture of micro-organism derived from the master seed lot and intended for use in production. Working seed lots are distributed into containers and stored as described above lor master seed lots. 

In order to prevent the unwanted drift of properties which might ensue from repeated subcultures or multiple generations, the production of biological medicinal products obtained by microbial culture, cell culture or propagation in embryos and animals should be based on a system of master and working seed lots and/or cell banks. 

Fig. 1.3 Diagram of a simple batch (or extended-batch) process with suspension cells. Cells are obtained from a Master- or Working Cell bank (MCB/WCB) and inoculated into spinners for a defined subcultivation period (every 3—4 days, usually for up to 100 days or more). For maintenance purposes of the culture, the cells in the spinner are referred to as the seed train". Cells...

Preclinical development comprises the technical and scientific elaboration of a process to manufacture the desired product on a large scale. Firstly, cell cultures and microorganisms to be used must be established as Master Cell Banks and Working Cell Banks, or as Master and Working Seeds, respectively. These ensure... 

The master cell bank can be used to inoculate agar slants or a seed medium to generate vegetative growth for liquid nitrogen storage. Either slants or ampoules can be subse-quently used as working cultures for inoculation of primary seeds. 

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