title: Chinese hamster ovary cells produce sufficient recombinant insulin-like growth factor I to support growth in serum-free medium. Serum-free growth of IGF-I-producing CHO cells.
abstract: Insulin-like growth factor I has similar mitogenic effects to insulin, a growth factor required by most cells in culture, and it can replace insulin in serum-free formulations for some cells. Chinese Hamster Ovary cells grow well in serum-free medium with insulin and transferrin as the only exogenous growth factors. An alternative approach to addition of exogenous growth factors to serum-free medium is transfection of host cells with growth factor-encoding genes, permitting autocrine growth. Taking this approach, we constructed an IGF-I heterologous gene driven by the cytomegalovirus promoter, introduced it into Chinese Hamster Ovary cells and examined the growth characteristics of Insulin-like growth factor I-expressing clonal cells in the absence of the exogenous factor. The transfected cells secreted up to 500 ng/10(6) cells/day of mature Insulin-like growth factor I into the conditioned medium and as a result they grew autonomously in serum-free medium containing transferrin as the only added growth factor. This growth-stimulating effect, observed under both small and large scale culture conditions, was maximal since no further improvement was observed in the presence of exogenous insulin.
authors.affiliation: Department of Biotechnology, University of New South Wales, Kensington, NSW, Australia.
authors.forename: S M
authors.initials: SM
authors.lastname: Hunt
authors.forename: S C
authors.initials: SC
authors.lastname: Pak
authors.forename: M W
authors.initials: MW
authors.lastname: Bridges
authors.forename: P P
authors.initials: PP
authors.lastname: Gray
authors.forename: M J
authors.initials: MJ
authors.lastname: Sleigh