Chinese hamster ovary expression cell lines

Most IFNs have now been produced in a variety of expression systems including E. coli, fungi, yeast and also some mammalian cell lines such as Chinese hamster ovary (CHO) cell lines and monkey kidney cell lines. Most IFNs currently in medical use are recombinant human (rh) products produced in E. coli. The inability of E. coli to carry out post-translational modifications is in most instances irrelevant, as the majority of human IFN-as, as well as IFN-jS, are not normally glycosylated. While IFN-y is glycosylated, the E. co/i-derived unglycosylated form displays a biological activity identical to the native human protein. 

Currently, it is standard procedure to develop ion channel-specific antibodies for immunocytochemistry, to perform Western and Northern blot analyses, ion channel in situ hybridization, or reverse transcription polymerase chain reaction (RT-PCR). The introduction of the single-cell RT-PCR in combination with the patch-clamp method in the 1990s made it possible to identify gene transcripts and to correlate them with functional data for the same individual cell. Finally, one of the most powerful cell biological techniques in the study of ion channels is based on artificial expression systems such as microinjection of mRNA encoding channel subunits into Xenopus oocytes and selective expression of native ion channels or with different subunit composition (e.g., Ky channel subunits). Because the Xenopus oocytes are large, they are a perfect model to study artificially expressed channels. Another good model for artificial ion channel expression is the Chinese hamster ovary (CHO) cell line. 

Although numerous cell lines have been screened for their efficiency as a host system for recombinant protein production, only a few have shown favorable properties for the expression of biopharmaceuticals (Hauser, 1997). Regulatory and economic issues for large-scale production and the intended application of the recombinant protein (diagnosis, therapy, etc.) have to be carefully considered (Makrides and Prentice, 2003). Three mammalian cell lines are now commonly used by the pharmaceutical industry Chinese hamster ovary (CHO) cells, the murine myeloma SP2/0 and the NS0 cell line (see Table 3.1). These cell lines have been used to produce 11 of 21 therapeutic products approved from 1996 to 2000 (Chu and Robinson, 2001). 

HMG-CoA reductase activity and LDL receptor levels always appear to change in the same direction in cells exposed to different levels of LDL. Similarly, a mutant line of Chinese hamster ovary (CHO) cells exposed to delipidated serum expresses low levels of both HMG-CoA reductase and LDL receptor activities compared to normal cells [88], Taken together, this evidence suggests coordinate expression of these two activities. 

During the last several years, our laboratory has developed a model of familial prion diseases by constructing stably transfected lines of Chinese hamster ovary (CHO) cells that express murine homologs of... 

To date, commercial antibody expression exclusively uses mammalian cell line expression. These mammalian cell lines have expression cassettes for the antibody heavy and light chain stably integrated into the host cell chromosome. The most commonly used cell lines are derived from Chinese hamster ovary (CHO) cells. About half the approved antibody therapeutics are made in CHO cell lines. The dihydrofolate reductase (dhfr) gene is used as a selectable marker owing to the development of CHO cell lines that are deficient for dhfr genes such as CHO DG44 and CHO... 

Levy, L. M., Warr, D., and Attwell, D. (1998) Stoichiometry of the glial glutamate transporter GLT-1 expressed inducibly in a Chinese hamster ovary cell line selected for low endogenous Na+-dependent glutamate uptake. J. Neurosci. 18,9620-9628. 

Clinical trials have demonstrated excellent efficacy with recombinant human factor VIII concentrates available as Recombinate and Kogenate. These recombinant factor VIII products are purified from the cell culture of plasmids, not viral DNA-transfected hamster cells and therefore do not express viral sequences. The addition of human serum albumin for stabilization, constitutes the sole possible source for human viral contamination. More recently recombinant factor IX has been genetically engineered by insertion of the human factor IX gene into a Chinese hamster ovary cell line. It has been proved to be safe and effective in the treatment of patients with hemophilia B. 

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