Recombinant (or genetically engineered) protein expression systems are used to produce large quantities of highly purified human proteins for clinical use. The yield of purified protein that a commercial production system is capable of producing is largely determined by the quality of the cell line used.
A cell line is essentially a genetically engineered population of identical cells which grow indefinitely in culture and which are capable of reproducing (or expressing) a particular type of gene or protein. When introduced into an industrial scale fermentation system, the cell line is induced to produce its specific gene or protein in large quantities.
A key determinant of cell line quality is the sophistication of the vector used to develop the cell line. A vector is a circular fragment of DNA that forms the basis of the cell line development process. By combining itself with DNA from the gene to be expressed by the cell line, the vector serves primarily as the carrier of this gene into the “host cells” which are used to clone (or reproduce) that gene. The efficiency with which the vector performs its “carrier” and related functions determines to a great extent the production capacity of the cell line.
