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A novel single‐use bioreactor was recently introduced to the market that is agitated by impellers suspended on flexible ropes rather than a rigid shaft. Computational fluid dynamics (CFD) models were created and validated by particle image velocimetry (PIV) to predict the bioreactor's fluid flow and mixing. The data were then used to scale‐up a Spodoptera frugiperda, subclone 9 (Sf9) insect cell‐based production of recombinant adeno‐associated virus (AAV) from a benchtop glass bioreactor to the single‐use system with 30 L working volume. This viral vector is one of the most commonly used in gene therapies. The volumetric power input was kept constant while maintaining reasonable mixing times and shear stresses between the scales. Peak cell densities of up to 7.2 × 106 cells mL−1 and maximum virus titers of 1.7 × 1011 vg mL−1 were achieved. Similar cell growth and metabolite profiles further proved the successful process transfer between the two geometrically non‐similar bioreactor systems. The pilot bioreactor yielded between 3.3 and 4.8 × 1015 vg that, depending on the therapy, can be sufficient for the treatment of a single patient. [ABSTRACT FROM AUTHOR]

Power input is an important engineering and scale-up/down criterion in stirred bioreactors. However, reliably measuring power input in laboratory-scale systems is still challenging. Even though torque measurements have proven to be suitable in pilot scale systems, sensor accuracy, resolution, and errors from relatively high levels of friction inside bearings can become limiting factors at smaller scales. An experimental setup for power input measurements was developed in this study by focusing on stainless steel and single-use bioreactors in the single-digit volume range. The friction losses inside the air bearings were effectively reduced to less than 0.5% of the measurement range of the torque meter. A comparison of dimensionless power numbers determined for a reference Rushton turbine stirrer ( NP = 4.17 ± 0.14 for fully turbulent conditions) revealed good agreement with literature data. Hence, the power numbers of several reusable and single-use bioreactors could be determined over a wide range of Reynolds numbers between 100 and >104. Power numbers of between 0.3 and 4.5 (for Re = 104) were determined for the different systems. The rigid plastic vessels showed similar power characteristics to their reusable counterparts. Thus, it was demonstrated that the torque-based technique can be used to reliably measure power input in stirred reusable and single-use bioreactors at the laboratory scale. [ABSTRACT FROM AUTHOR]

The innovative travelling wave bioreactor (TWB), an orbitally shaken system, developed specifically for cell culture applications, is investigated. In this study, engineering parameters covering power input, mixing time and oxygen mass transfer obtained in two TWB prototypes are presented for the first time. Based on the results, cultivation parameters for CHO suspension cell cultivations were defined. Cell growth and substrate consumption were comparable with a wave-mixed reference bioreactor, which demonstrates the bioreactor's applicability for cultivations of mammalian cell cultures for the first time. [ABSTRACT FROM AUTHOR]

In the travelling wave bioreactor (TWB) an orbital movement is used to set up a quasi-periodic wave motion in the partially filled, toroidal shaped vessel. Based on computational fluid dynamics (CFD) models, this study presents detailed analyses of the fluid flow in the TWB for a wide range of operational conditions. Even though the wave propagation is shown to be greatly influenced by the rotation, it was found that the regular vessel shape facilitates a predominantly tangential flow with low back mixing, irrespective of the operational conditions. Hence, the influence of different bioreactor geometries without and with baffles is examined. The study indicates that CFD models can be used as a valuable tool for bioreactor development, because it provides a deep insight into the bioreactor's hydrodynamics and can help to reduce the number of prototypes. [ABSTRACT FROM AUTHOR]

The suitability of oil-water emulsions to predict shear forces in stirred bioreactors under cost-effective and time-saving conditions has been demonstrated several times, but no application to pumps has been described so far. In this report, the drop sizes in a model oil-water system were determined for the Levitronix PuraLev® multiuse (MU) series (PuraLev® 200MU and PuraLev® 600MU), a peristaltic pump (Masterflex® I/P Easy Load), and 4-piston diaphragm pump (Quattroflow 1200-SU, where SU is single-use) using inline endoscopy. It was determined that the Sauter mean diameter could be used as a comparison criterion to estimate mechanical stress in pumps. The investigation showed that PuraLev® MU pumps are characterized by up to 59% larger Sauter mean diameters than their counterparts at comparable operational conditions. This indicates lower hydrodynamic stress in the PuraLev® MU pumps. Using computational fluid dynamics, a well-streamlined fluid flow and low turbulent energy dissipation rates were found in the PuraLev® MU pumps, which correlated well with experimental results. A calculation model was used to predict the Sauter mean diameter by combining both experimental and computational fluid dynamics data. Good agreement with deviations below 13% was determined between model predictions and experimental data. [ABSTRACT FROM AUTHOR]

Suspension cultures, in which human mesenchymal stem cells are cultivated on microcarriers in scalable single-use stirred bioreactor types, have been shown to be a promising alternative to planar flask cultures. However, stirred single-use bioreactors were originally developed for production processes with robust, permanent cell lines. Human mesenchymal stem cells are adherent primary cells and thus expanding them in such bioreactor systems imposes more stringent requirements on bioreactor systems. For low-serum conditions (5%) and different types of stirred single-use bioreactors, a suspension criteria-based approach for expanding human adipose tissue-derived mesenchymal stem cells (hASCs) from milliliter to pilot scale was successfully developed. For process scale-up, experimental and numerical investigations were performed to (i) predict optimum impeller speeds, (ii) determine the main engineering parameters (local shear stress, turbulent dissipation rate, Kolmogorov microscale), and (iii) verify suspension criteria NS1 and NS1u for rapid process transfer from 100 mL to 2 L and 35 L cultures. Using optimized medium-microcarrier combinations as well as NS1 and NS1u as scale-up factors, total hASC quantities between 3 × 107 (100 mL scale) and 1 × 1010 (35 L scale) were obtained. The cell quantities obtained are the highest reported to date for scalable single-use bioreactors under low-serum conditions. [ABSTRACT FROM AUTHOR]

Mechanical stress caused to transfected Chinese hamster ovary (CHO) suspension cells by reusable and single-use magnetically levitated, bearingless centrifugal pumps was investigated. Cell death rates were determined for different pump speeds and compared with data from a peristaltic and a 4-piston diaphragm pump. Furthermore, the fluid distribution inside the PuraLev® 200 pump was modeled using computational fluid dynamics. The results reveal considerably lower mechanical stress to CHO cells caused by the magnetically levitated bearingless centrifugal pumps than by the peristaltic and diaphragm pump. [ABSTRACT FROM AUTHOR]

This study presents the concept of the travelling wave single-use bioreactor, based on an orbitally shaken, annular-shaped vessel. A numerical model was developed for early design studies in order to reduce the number of prototypes. The flow characteristics in two different vessel shapes were investigated. It was shown that the orbital motion combined with the toroidal shape of the bioreactor create the desired wave characteristics in the contents of the vessel. [ABSTRACT FROM AUTHOR]

The article presents a study which discusses expansion of mesenchymal adipose-tissue derived stem cells in a single-use bioreactor under low-serum conditions. Topics discussed include increase in demand of human mesenchymal stem cells (hMSCs), use of preliminary tests in disposable-spinners to determine microcarrier (MC) types for serum reduced expansions, and flow cytometry tests revealing marker profiles following cell expansion and harvest.