(567ak) A 24-Well Microbioreactor Array with Improved Mixing for High-Throughput Cell Cultures

Multiwell plates are increasingly used in high throughput drug screening, cell clone development, media design and cell culture optimization in the biotechnology industry. The reproducibility and data quality of multiwell cell cultures can be greatly affected by mixing and aeration conditions but have not been well studied. In this work, the performance of cell cultures in a 24-well microbioreactor array, which has similar dimensions and well locations to those of commercial 96-well plates, was studied with online monitoring of the growth of Chinese Hamster Ovary (CHO) cells expressing green fluorescence protein (GFP). To enable optical monitoring and real-time quantification of cell proliferation, the bottom of the multiwell plate was made of a poly(dimethylsiloxane) (PDMS) membrane, which is permeable to oxygen and can also provide good oxygenation of culture media. In addition, each microbioreactor also contained a static mixer located at the center of the well. Mixing, oxygen transfer and cell proliferation as affected by the static mixer and agitation rate were studied. In general, the static mixer improved mixing pattern and reduced cell aggregation under orbital shaking conditions. The static mixer also improved cell proliferation with a significantly higher specific growth rate in round wells because of improved mixing and oxygen transfer. Furthermore, cell cultures at different locations on the plate showed consistent growth and metabolic profiles. Compared to the control wells without a static mixer, the static mixer significantly improved data quality with smaller standard errors and better reproducibility. Finally, the 24-well microbioreactor array was used to study monoclonal antibody production by CHO cells in a serum-free medium. The results were consistent with those from the spinner flask cultures, demonstrating scalable performance of the 24-well microbioreactor array.