Theoretical and Practical Issues That Are Relevant When Scaling Up hMSC Microcarrier Production Processes

Abstract

The potential of human mesenchymal stem cells (hMSCs) for allogeneic cell therapies has created a large amount of interest. However, this presupposes the availability of efficient scale-up procedures. Promising results have been reported for stirred bioreactors that operate with microcarriers. Recent publications focusing on microcarrier-based stirred bioreactors have demonstrated the successful use of Computational Fluid Dynamics (CFD) and suspension criteria (N S1u, N S1) for rapidly scaling up hMSC expansions from mL- to pilot scale. Nevertheless, one obstacle may be the formation of large microcarrier-cell-aggregates, which may result in mass transfer limitations and inhomogeneous distributions of stem cells in the culture broth. The dependence of microcarrier-cell-aggregate formation on impeller speed and shear stress levels was investigated for human adipose derived stromal/stem cells (hASCs) at the spinner scale by recording the Sauter mean diameter (d 32) versus time. Cultivation at the suspension criteria provided d 32 values between 0.2 and 0.7 mm, the highest cell densities (1.25 × 106 cells mL−1 hASCs), and the highest expansion factors (117.0 ± 4.7 on day 7), while maintaining the expression of specific surface markers. Furthermore, suitability of the suspension criterion N S1u was investigated for scaling up microcarrier-based processes in wave-mixed bioreactors for the first time.

Microcarriers for Upscaling Cultured Meat Production

“…It has been shown that successively transferring a small proportion of near-confluent MCs (10-25%) into a new vessel loaded with fresh MCs leads to a decrease of lag phase and an increase of the overall yield (35,38). Even if using MCs can lead to the formation of cell-loaded MCs aggregates that can inhibit proliferation, adding fresh MCs in combination with adapted agitation have been shown to reduce MCs aggregation (41)(42)(43). Although different techniques, such as intermittent stirring, have been implemented to enhance cell transfer and limit clumping of MCs, no robust method for SCs has been reported so far.…”

Aggregation kinetics of human mesenchymal stem cells under wave motion

“…In the present study, we attempt to investigate the influence of hydrodynamic conditions on aggregation kinetics of hMSC on a rocking platform. Rocking cultures characterized by intermittent wave motion are not only used in laboratory stem cell culture but also in large scale production such as in wave motion bioreactors . Using a rocking platform with controllable rocking conditions, the results of the present study reveal quantitative relations between hMSC aggregation kinetics and hydrodynamics, and demonstrate the potential of the rocking platform for large scale production of hMSC aggregates.…”

Mesenchymal stromal cell-based therapy: Regulatory and translational aspects in gastroenterology

“…The application of this novel technology highlighted the need for further standard in-culture conditions aimed at stabilizing MSC phenotype. These include medium flow rate, sheer tension[49] and cell-microcarrier interactions[50]. …”