Good Manufacturing Practice-grade fibronectin for hollow-fiber bioreactor cell manufacture: a mesenchymal stromal cell case study

Background aims: The need for large-scale production of mesenchymal stromal cell (MSC)-based cellular therapeutics continues to grow around the globe. Manual cell expansion processes can be highly variable between operators, require significant hands-on time from skilled staff and, because of the large number of open manipulation steps required to produce cells in dose-relevant quantities, be prone to greater risk of contamination relative to automated processes. All of these can increase overall production costs and risks to the patient. In order to meet the needs of this growing industry, viable options for large-scale automation coupled with consistent and compliant ancillary materials needed to drive cell expansion are needed.

Methods: In the work described herein, the automated and functionally closed hollow-fiber bioreactor system Quantum Flex (Terumo Blood and Cell Technologies, Inc., Lakewood, CO, USA) was used in conjunction with Good Manufacturing Practice (GMP)-compliant, virus-inactivated human fibronectin (FN) from Akron Bio (Boca Raton, FL, USA) to expand MSCs to clinically relevant numbers. In order to assess the performance of Akron Bio's GMP-grade FN, use of this product in the production of MSCs was referenced against use of a research-use-only (RUO)-grade FN product used extensively for MSC expansion in Quantum. Because many MSC-based processes require passaging of cells to attain the appropriate number of cells needed, a two-passage process was employed comparing the transfer of MSCs expanded on RUO FN to RUO FN, GMP FN to GMP FN and RUO FN to GMP FN to assess the impacts of transitioning from one grade of FN to another, as a product might be required to do as it moves from pre-clinical to clinical stages and beyond.

Results: No statistically significant differences were noted when MSCs were transferred from RUO FN to RUO FN, GMP FN to GMP FN or RUO FN to GMP FN in terms of harvest yield, population doubling time, seeding efficiency estimates or fold expansion. All MSCs harvested from all groups met International Society for Cell & Gene Therapy standards for MSCs in terms of protein marker expression measured by flow cytometry, adherence to plastic, downstream cell morphology and trilineage differentiation.

Conclusions: The combination of Quantum Flex as an expansion platform and Akron Bio's GMP FN is seen as an attractive option for larger-scale manufacture of GMP-grade MSC products.