title: Isolation, characterization and recombinant protein expression in Veggie-CHO: A serum-free CHO host cell line.
abstract: The dihydrofolate reductase-deficient Chinese hamster ovary cell line, DXB11-CHO, commonly used as a host cell for the production of recombinant proteins requires 7.5% serum-supplementation for optimal growth. Regulatory issues surrounding the use of serum in clinical production processes and the direct and indirect costs of using serum in large-scale production and recovery processes have triggered efforts to derive serum-independent host cell lines. We have successfully isolated a serum-free host that we named Veggie- CHO. Veggie-CHO was generated by adapting DXB11-CHO cells to growth in serum-free media in the absence of exogenous growth factors such as Transferrin and Insulin-like growth factor, which we have previously shown to be essential for growth and viability of DXB11- CHO cells. Veggie-CHO cells have been shown to maintain an average doubling time of 22 hr in continuous growth cultures over a period of three months and have retained the dihydrofolate reductase -deficient phenotype of their parental DXB11-CHO cells. These properties and the stability of its serum-free phenotype have allowed the use of Veggie- CHO as host cells for transfection and amplified expression of recombinant proteins. We describe the derivation a serum-free recombinant cell line with an average doubling time of 20 hr and specific productivity of 2.5 Units recombinant Flt-3L protein per 10e6 cells per day.
authors.affiliation: Cell Sciences Department, Immunex Corporation, 51 University Street, Seattle, WA, 98101, U.S.A.
authors.forename: B
authors.initials: B
authors.lastname: Rasmussen
authors.forename: R
authors.initials: R
authors.lastname: Davis
authors.forename: J
authors.initials: J
authors.lastname: Thomas
authors.forename: P
authors.initials: P
authors.lastname: Reddy