|Publication type:||Conference poster|
|Type of review:||Not specified|
|Title:||Impact of shear stress on cell growth and microcarrier-cell-agglomerate formation in microcarrier-based cultivations of adipose tissue-derived stromal/stem cells|
|Conference details:||BioTech 2016, Wädenswil, Switzerland, 5-8 September 2016|
|Subject (DDC):||610.28: Biomedicine, biomedical engineering |
660: Chemical engineering
|Abstract:||Cell-based therapies have become increasingly important in the field of regenerative medicine, as global revenues of approximately 1 billion US$ indicate. A special focus in the clinical field is placed on human mesenchymal stem cells (hMSCs), especially on those isolated from the stromal vascular fraction of the adipose tissue. Due to their good clinical efficacy and tolerability, they can be used for allogeneic cell therapies (e.g. Crohn’s disease, graft versus host disease, acute myocardial infarct). However, the required number of therapeutically active human adipose tissue-derived stromal/stem cells (hASCs) for allogeneic applications is in the range of trillion cells per year. Thus, alternatives to the 2-dimensional planar cultivation systems, typically applied to propagate hASCs are urgently required. Different studies have recently demonstrated the applicability of stirred single-use bioreactors as a promising alternative to the planar cultivation systems. In these dynamically mixed culture systems, the required growth surface for the adherent growing cells is provided by microcarriers (MCs), which are suspended in the bioreactor. Although adherent mammalian cells are well investigated in combination with MCs for the production of vaccines, working with hASCs is more complex due to their higher shear sensitivity. This raises the question of how the induced fluid shear stress affects the cell expansion, the cell quality and the formation of MC-cell agglomerates during the cultivation in dynamic bioreactors. For this purpose, MC-based cell expansions were performed in single-use spinner flasks at different impeller speeds below (25, 43 rpm) and above (90 and 120 rpm) the specific suspension criteria NS1u (49 rpm) and NS1 (63 rpm) for polystyrene-based MCs. Cell numbers, metabolites and the formation of MC-cell agglomerates were measured during the cell expansion process. Furthermore, the expression of standard surface markers (CD14, CD20, CD34, CD45, CD73, CD90, CD105) for hASCs were analysed after harvesting of the cells. Beside the biological investigations, Computational Fluid Dynamics simulations were performed in order to predict the velocity gradients and the hydrodynamic forces. The results indicated that too low (25 rpm) and too high impeller speeds (120 rpm) result in statistically significant lower cell densities (0.81 and 0.25 x 106 cells/mL) compared to those at the suspension criteria (1.25 and 1.11 x 106 cells/mL). These lower cell densities can be ascribed to mass transport limitations at low impeller speeds and to too high hydrodynamic strains at high impeller speeds. The effect of the shear stress on the MC-cell agglomerate formation at high impeller speeds was not significant, when compared the Sauter mean diameters to those resulting at the suspension criteria. In contrast, impeller speeds below the suspension criteria resulted in a strong MC-agglomerate formation, which may support mass transfer limitations.|
|Fulltext version:||Published version|
|License (according to publishing contract):||Licence according to publishing contract|
|Departement:||Life Sciences and Facility Management|
|Organisational Unit:||Institute of Chemistry and Biotechnology (ICBT)|
|Appears in collections:||Publikationen Life Sciences und Facility Management|
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