Raining Blood: Scale-Up Of Ex Vivo Erthroblast Expansion For The Production Of RBCs For Transfusion Purposes

By Gallego Murillo, J.; Bernal, C.; van Arragon, T.; van der Wielen, L.; van den Akker, E.; von Lindern, M.; Wahl, A.

Transfusion of donor-derived red blood cells (RBCs) is the most common form of cell therapy. Nevertheless, it faces challenges such as emerging blood-borne diseases, and supply limitations; for instance, in low-income countries, or for chronically transfused patients requiring special blood groups. Production of cultured RBCs (cRBCs) is one solution. Erythroid precursors can be cultured from hematopoietic progenitors, and differentiated into transfusion-ready cRBCs. The large number of cRBCs required for a single transfusion unit requires major innovations in the culture process.

Expansion and differentiation were successfully scaled from static culture conditions (culture dishes of 10 – 12 mL) to 0.5 L stirred bioreactors. Next step is to further scale-up the erythroblast expansion, the stage in which most of the cell proliferation takes place. We have performed expansion cultures in AppliFlex ST 3.0 L stirred bioreactors, following a repeated batch cultivation strategy, and using tip speed as scale-up parameter.

Erythroblast growth rate, viability, and differentiation dynamics were maintained during 9 days of culture when scaling up the cultivations from the 0.5 L to the 3.0 L bioreactors. Concentration of lactate in the supernatant of bioreactor cultures was lower than in culture dishes, probably reflecting to a better control of oxygen availability in the bioreactors. This study demonstrates the first steps towards the scaling up of erythroblast expansion in a GMP-compatible bioreactor setup.