Characterization of TAP Ambr 250 disposable bioreactors, as a reliable scale‐down model for biologics process development

Abstract

Demands for development of biological therapies is rapidly increasing, as is the drive to reduce time to patient. In order to speed up development, the disposable Automated Microscale Bioreactor (Ambr 250) system is increasingly gaining interest due to its advantages, including highly automated control, high throughput capacity, and short turnaround time. Traditional early stage upstream process development conducted in 2 - 5 L bench-top bioreactors requires high foot-print, and running cost. The establishment of the Ambr 250 as a scale-down model leads to many benefits in process development. In this study, a comprehensive characterization of mass transfer coefficient (k a) in the Ambr 250 was conducted to define optimal operational conditions. Scale-down approaches, including dimensionless volumetric flow rate (vvm), power per unit volume (P/V) and k a have been evaluated using different cell lines. This study demonstrates that the Ambr 250 generated comparable profiles of cell growth and protein production, as seen at 5-L and 1000-L bioreactor scales, when using k a as a scale-down parameter. In addition to mimicking processes at large scales, the suitability of the Ambr 250 as a tool for clone selection, which is traditionally conducted in bench-top bioreactors, was investigated. Data show that cell growth, productivity, metabolite profiles, and product qualities of material generated using the Ambr 250 were comparable to those from 5-L bioreactors. Therefore, Ambr 250 can be used for clone selection and process development as a replacement for traditional bench-top bioreactors minimizing resource utilization during the early stages of development in the biopharmaceutical industry. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:478-489, 2017.

Scale-down of CHO cell fed-batch cultures

“…Insufficient O2 transfer results in O2 limitation, which leads to slower cell growth, changes in cell metabolism, cell death, and changes in product quality 179,197 . In practice, the O2 volumetric mass transfer coefficient (kLa) is often used as a criterion during scale-up/down 37,165,196,198 . Matching the kLa ensures that similar maximum O2 transfer rates (OTRs) can be obtained between scales.…”

“…Research has been done to investigate maximum allowed power input per volume (W/kg, also called volumetric energy dissipation rate, from here on symbolized as [ε]) for mammalian cells 37,38,165,177,196,214 . The results of these studies indicate that shear generated from agitation is generally well below the critical level of mammalian cells.…”

“…Different scale-down criteria can be used to develop a representative small-scale process. These criteria include, for example, the oxygen volumetric mass transfer rate (kLa), the volumetric power input (P/V), and the agitator tip speed 43,165 . Production scale reactors can be properly scaled down to bench-scale reactors (1-10 L) which are traditionally used as the main platform for process development 37,41 .…”

“…The mL-scale systems were originally designed for quick screening of clones, media, and culture parameters such as pH and temperature. In recent years, many studies 165,172,190,191 have shown that these mL-scale systems are quite representative for the bioreactors ranging from L-scale to kL-scale.…”

“…Therefore, the pCO2 level will build up with the use of micro-sparging. In order to reduce the pCO2 level in these bioreactors, an additional sparger generating large bubbles with air or N2 is used for stripping CO2 165,209 . In this way, the DO and pCO2 can be independently controlled.…”