Discussion of all aspects of cellular structure, physiology and communication.
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Although a variety of mammalian cell hosts are available for protein production, only a small number have emerged as systems of choice for production of proteins to be used clinically.The narrowing down of choices is largely due to the need for cell lines that:
(1) are capable of continuous growth; (2) can be grown in suspension (in bioreactors);(3) have low risk of adventitious infection by potentially pathogenic viruses; (4) have genetic stability; and (5) can be readily characterized with respect to karyology, morphology, isoenzymes, and gene copy number. The existence of a variety of host-cell systems, the availability of viral or cDNA-based vectors, and the possibility of either stable or transient expression requires that the prospective user define an expression strategy based on ultimate goals. When the researcher’s objectives require <1 mg of protein, transient expression in COS-7 cells is the relevant route. Transient expression in the COS-cell and vaccinia systems has been recently reviewed (Moss and Earl, 1991; Aruffo, 1997), and detailed protocols for construction of suitable vectors and protein expression by these systems can be found in those articles. In transient expression a burst of production occurs in the host cell and is usually accompanied by death and rapid lysis of the cell. This presents the purification scientist with the challenge of fishing out the protein of interest, which may be present at 5 g/ml, from a soup of lysed cellular protein, nucleic acids, and viral particles. The yield of product during purification may be low as a result of the low titer and starting purity; however, when only small quantities of protein are required, transient expression in COS cells or the vaccinia system is a quick and suitable system to employ. For production of larger quantities of protein, stable expression must be used because of the difficulty in scaling up transient expression into a bioreactor system.Some cell lines have successfully been used as hosts in production of proteins and viruses.
Thanks for your share.
Do we need to consider the relationship between the host cell, vector and protein we want to expression? Sometime good choice to lead to high expression of protein, but bad choice will result less protein amount. So how shall we chose them?
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CreativeBiomart, Recombinant protein expert
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