Scalability of the Mobius CellReady Single-use Bioreactor Systems

The author defines the process-design space and demonstrates scalability of a single-use, stirred-tank bioreactor.
Apr 02, 2013

Image courtesy of EMD Millipore
The Mobius CellReady family of products includes the bench-scale (3-L), small-scale (50-L) and pilot-scale (200-L) bioreactor systems that enable cell growth in volumes appropriate for early process development through clinical batch production. The small-scale Mobius CellReady 3-L bioreactor is a rigid, stirred-tank bioreactor (see Figure 1A) while the Mobius CellReady 50-L and 200-L bioreactor systems (see Figures 1B and 1C) are inflatable stirred-tank bioreactor process containers used in stainless-steel vessels. Table I outlines the features of all three. Both the Mobius CellReady 50-L and 200-L bioreactor process containers use the Mobius SensorReady technology for process monitoring and control. The Mobius SensorReady assembly is an external loop that is connected to the bioreactor process container that allows for a configurable number of probes and sensors to be used.

Figure 1: (A) 3-L Mobius CellReady bioreactor; (B) 50-L; and (C) 200-L Mobius CellReady bioreactor process containers.
The ability to scale up a biomanufacturing process is essential for process development and the production of biologics. Bioreactor process set points, acceptable ranges, and general operating parameters used at the large scale are commonly based on those developed at the benchtop or small scale where experimentation is more cost effective and efficient. Large-scale performance and production expectations are often established based on results obtained at smaller scales. It is, therefore, important that the process parameters developed at the small scale are readily transferrable to the larger scale.

Table I: Comparison of the features of 3-L, 50-L, and 200-L CellReady bioreactors.
Challenges to bioreactor scale-up occur because even when two geometrically similar tanks are used, it is not possible to simultaneously maintain key bioreactor characteristics such as shear, mixing time, and oxygen mass transfer coefficient (kLa) identical in both the large and small tanks (1). Other variables, such as bubble size and distribution, nutrient regulation and delivery, and process control capabilities may also contribute to variable performance results across scales. Ultimately, successful scale-up is determined when comparable process performance endpoints such as cell growth, cell viability, protein production, and product quality are achieved. The probability of meeting these criteria can be increased when the bioreactor systems are well-characterized and the process design space is better understood.

In this study, several key engineering parameters kLa, power-per-unit volume, Reynolds number (Re), mixing time, and tip speed were characterized for the three different sized single-use bioreactor process containers. Chinese hamster ovary (CHO) cells were then cultured in each of these bioreactor systems based on maintaining equivalent power per unit volume as the primary scaling parameter. The results of this study define the characterization and process design space offered by the bioreactor systems and demonstrates the capability to achieve expected cell culture performance results across scales, thus demonstrating the scalability of the family of Mobius CellReady bioreactor systems.

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