Scaling a xeno-free fed-batch microcarrier suspension bioreactor system from development to production scale for manufacturing XF hMSCs

Abstract

Background & Aim With over 800 clinical trials investigating the use of mesenchymal stem/stromal cells (hMSCs) for regenerative medicine, there is an urgent need for the development of economical biomanufacturing processes capable of generating billions to trillions of cells per manufacturing lot in order to meet the demand of future commercial applications. Innovative manufacturing technologies, such as suspension bioreactors, show great promise in reaching commercially-viable working volumes; however, scalability of cell production within such systems remain a challenge, hindering widespread adoption of this culture system for hMSCs. The Quality by Design (QbD) approach was used to develop a scalable xeno-free (XF) hMSC bioreactor process that maintains the final cell population doubling level (PDL) within the recommended range (16-20) to ensure product quality, even as the bioreactor culture volume is scaled to hundreds of liters. The strategic XF bioprocess was designed using high volume XF cell banks, an optimized XF fed-batch media system, and XF microcarriers combined with a scalable bioreactor system to meet design criteria and streamlined production at different culture scales. Methods, Results & Conclusion In this study, the ability to scale XF hBM-MSC expansion in low shear single-use, Vertical-Wheel suspension bioreactors (PBS Biotech) was evaluated in systems of different scale including: small scale (0.1L), development scale (3L), pilot scale (15L), and production scale (50L) reactors. Cell densities greater than 500,000 cells/mL (with >95% viability) were achieved within 4 to 5 days of fed-batch culture at each bioreactor scale. Scalability of the bioreactor culture process was supported by comparable nutrient and waste metabolite profiles, cell growth curves, and pH observed in each system. Furthermore, harvested cells from each bioreactor scale demonstrated comparable critical hMSC quality attributes including angiogenic cytokine (FGF, HGF, IL-8, TIMP-1, TIMP-2, and VEGF) secretion, tri-lineage differentiation potential, and inducible immunomodulatory potential (as measured by functional IDO activity) compared to control cells of similar PDL cultured in 2D. The data generated by this study demonstrates the expansion of XF hBM-MSCs in a scalable bioreactor culture system, providing significant time and cost savings as a plug-and-play standardized system for translational researchers and product developers in the regenerative medicine, tissue engineering, and cell therapy fields.