A novel metal-inducible and amplifiable metallothionein (MT) expression system, pNK, was firstly optimised and characterised for the production of a reporter protein, human growth hormone (hGH) in a suspension CHO cell line grown in a serum-free media. The pNK-based hGH production was demonstrated in cadmium-free condition under various fermentation modes (batch, fed-batch and perfusion) and scales (flask to bench-top bioreactor). Improvement of specific productivity of recombinant protein from pNK was shown to be possible by addition of butyrate or substrate substitution of glutamine by glutamate. Combination of fed-batch and butyrate addition strategies resulted in more than one gram per litre of hGH being obtained from the pNK expression system in a bioreactor. In the second part of the project, based on a statistical approach suggested by Plackett-Burman (P-B), a chemically-defined and protein-free medium, named Super-CHO protein-free (SPF), was developed to support a Super-CHO cell line, C2.8-325, to grow as a single-cell suspension culture with comparable growth rate and viable cell number as observed in a commercial medium containing undefined additives. Using Dulbecco's Modified Eagle's Medium/Ham's F12 1:1 mixture (DMEM/F12) as the basal medium, a P-B design matrix screened 10 nutritional components. Components shown potentially beneficial for cell growth rate and viable cell number were supplemented to DMEM/F12 to formulate the SPF medium. Finally, the pNK expression system and the Super-CHO cell line were applied simultaneously in an attempt to express a humanised anti-CD48 monoclonal antibody (MAb), IgG1-N2A (N2A-MAb). This aimed to test C2.8-SPF grown in newly developed SPF medium for transfection, clone development and recombinant protein production. A stable and N2A-MAb expressing C2.8-SPF cell line was successfully constructed, and N2A MAb expression was subsequently amplified and demonstrated in various cultivation scales (flask and bioreactor). This project demonstrated that the novel metal-inducible and - amplifiable mammalian expression system, pNK, and the novel mammalian host cell-line, Super-CHO C2.8-SPF, capable of growing as a single-cell suspension culture in a chemically-defined protein-free medium, SPF, could be utilised in combination to provide a new, low-cost, and regulatory-compliant recombinant protein expression platform, suitable for the biopharmaceutical industry to use in the manufacture of therapeutic recombinant proteins.
| Identifer | oai:union.ndltd.org:ADTP/234088 |
| Date | January 2006 |
| Creators | Huang, Edwin P.C., Biotechnology & Biomolecular Sciences, Faculty of Science, UNSW |
| Publisher | Awarded by:University of New South Wales. School of Biotechnology and Biomolecular Sciences |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright Edwin P.C. Huang, http://unsworks.unsw.edu.au/copyright |
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