Application of bioreactor design principles and multivariate analysis for development of cell culture scale down models

Abstract

A bench scale cell culture model representative of manufacturing scale (2,000 L) was developed based on oxygen mass transfer principles, for a CHO-based process producing a recombinant human protein. Cell culture performance differences across scales are characterized most often by sub-optimal performance in manufacturing scale bioreactors. By contrast in this study, reduced growth rates were observed at bench scale during the initial model development. Bioreactor models based on power per unit volume (P/V), volumetric mass transfer coefficient (kL a), and oxygen transfer rate (OTR) were evaluated to address this scale performance difference. Lower viable cell densities observed for the P/V model were attributed to higher sparge rates and reduced oxygen mass transfer efficiency (kL a) of the small scale hole spargers. Increasing the sparger kL a by decreasing the pore size resulted in a further decrease in growth at bench scale. Due to sensitivity of the cell line to gas sparge rate and bubble size that was revealed by the P/V and kL a models, an OTR model based on oxygen enrichment and increased P/V was selected that generated endpoint sparge rates representative of 2,000 L scale. This final bench scale model generated similar growth rates as manufacturing. In order to take into account other routinely monitored process parameters besides growth, a multivariate statistical approach was applied to demonstrate validity of the small scale model. After the model was selected based on univariate and multivariate analysis, product quality was generated and verified to fall within the 95% confidence limit of the multivariate model.

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

“…Power per unit volume ( P/V ), is a function of multiple parameters including impeller diameter, agitation rate and gassing conditions . A P/V model is often used in the situations with no limits on air/oxygen flow rates . As constant air flow rates were used together with a cap set to the cascade‐controlled oxygen supply in large‐scale cell culture processes, the model of both vvm and P/V was evaluated to cover the gassing and agitation strategies.…”

“…In the scale‐down or scale‐up of a process, the scale‐independent parameters are maintained across different scales, which include pH setting, DO setting, temperature, inoculation cell density and cell age. The process is scaled‐down or scaled‐up based on scale‐dependent parameters, such as power per unit volume ( P/V ), volumetric flow rate (vvm), and volumetric mass transfer coefficient ( k L a ) . Scale‐dependent criteria, such as tip speed and mixing time, are sometimes options in the scale‐down or scale‐up of a process.…”

Reduced scale model qualification of 5‐L and 250‐ml bioreactors using multivariant visualization and Bayesian inferential methods

“…These dimension‐reduction techniques allow comparison between scales by visual inspection. For example, Tescione, Lambropoulos, Paranandi, Makagiansar, and Ryll (2015) and Janakiraman, Kwiatkowski, Kshirsagar, Ryll, and Huang (2015) used the principal components analysis (PCA) procedure (Wold, Esbensen, & Geladi, 1987) to qualify both lab scale (5 L) and desktop scale (15 ml) visually. This overcomes the problem of only comparing one response at a time.…”

A novel scale‐down mimic of perfusion cell culture using sedimentation in an automated microbioreactor (SAM)

“…Cell culture media optimization, process optimization and the screening of clones are fast and inexpensive to perform in high‐throughput models when compared to the process‐scale, which could be a bioreactor of several cubic meters in volume. To have reliable results for process and cell line development, those activities should be ideally performed under conditions that are representative of the production‐scale . Development at final production scale is usually not economic due to a high resource demand.…”