The Engineering of a Scalable Disposable Orbitally Shaken Bioreactor System for Animal Cell Cultivation and Therapeutic Protein Production

Abstract

The aim of the pharmaceutical industry is to manufacture complex therapeutic proteins or biologics to treat human diseases. The manufacture of biologics requires a significant amount of financial and infrastructure resources. For this reason, efforts are being made in the industry to develop more effective, flexible and cost-efficient bioprocesses. This thesis focused on the development and characterization of a new disposable bioreactor for the scale-up of animal cell cultures for the production of therapeutic proteins. These disposable orbitally shaken bioreactors (OSRs) are beginning to be used in the biopharmaceutical industry and are a potential alternative to stirred-tank bioreactors (STRs) for small- and production-scale bioprocess. With cell culture volumes of mL to 2000 L available, a scale-up platform using only OSRs is feasible, but has yet to been tested. However, little is understood about OSRs above the bench-scale. Therefore, we investigated which small-scale OSR would be optimal for mammalian cell culture and then investigated a potential OSR scale-up bioprocesses that included newly developed pilot- and production-scale OSRs with working volumes of 200 L and 2500 L, respectively. When compared to the Erlenmeyer shake flask and cylindrical bottle, the TubeSpin bioreactor 600 exhibited a higher oxygen mass transfer coefficient and more efficient carbon dioxide stripping, while mammalian cell growth and recombinant protein production profiles were similar. Next, a study investigating protein quality and the effect of pH modulation in OSRs and STRs was performed in 3-L STRs and 5-L cylindrical bottles. Based on specific power consumption and mixing measurements, the OSR was found to be a more energy efficient system compared to the STR. Similar viable cell growth and recombinant protein production profiles in pH-controlled and non-controlled cultures were observed in both OSRs and STRs. However, a higher galactosylation index was observed for the recombinant protein produced in OSRs relative to that recovered from the STRs. To investigate the potential for the large-scale manufacture of recombinant proteins with OSRs, a scale-up bioprocess platform was developed for cell cultivation at scales from 10 mL to 2000 L. Similar engineering principles, mammalian cell growth, and recombinant protein production profiles were observed at all OSR scales. However, minor cell damage was found in the production-scale OSR. In order to further optimize the pilot- and production-scale OSRs, scale-down models were constructed. Wave patterns in the pilot- and production-scale OSRs were reproduced with the scale-down models. In addition, the scale-down models displayed similar engineering parameters as the pilot- and production-scale OSRs and the trends in cell growth and protein production were similar, validating the scale-down models. Subsequently, different bioprocesses were performed in small-scale OSRs in order to validate the technology for other applications. Microcarrier-based cell cultures and suspension-adapted insect cell cultures were performed using the OSR platform. In both cases, excellent cell growth was observed, demonstrating the flexibility of the OSR cell culture platform. In conclusion, the feasibility to perform large-scale bioprocesses with OSRs for the production of biologics at scales up to 2000 L has been demonstrated with animal cells in suspension and on microcarriers.