Abstract: Blood transfusion is currently the most common cell therapy applied worldwide to treat various medical purposes [1]. One of the purposes is the treatment of severe anemias, as these diseases can only be treated with blood transfusions and stem cell transplantations. An attractive therapy that could overcome the risks involved with donor-derived transfusion products is in vitroproduced red blood cells (RBCs) or the corresponding stem cells, namely hematopoietic stem cells (HSCs) [2,3]. In vitro RBCs can be produced from induced pluripotent stem cells (iPSCs), which are pluripotent cells created by reprogramming human somatic cells. This reprogramming technique started a new era in regenerative medicine due to their self-renewing properties and multilineage differentiation potential to produce patient-specific progenitor or functional effector cells [4, 5]. However, hematopoietic cells and RBCs from iPSC are mostly produced via multiple differentiation steps using static adherent protocols which hinders scalability towards clinically relevant volumes. A dynamic shake flask cultivation was developed to produce hematopoietic stem/progenitor cells (HSPCs), which can further be differentiated into functional RBCs. The dynamic cultivation led to a ~16,000 fold increase in cell number compared to static cultivation. This project aims to transfer the developed protocol to a suspended stirred-tank bioreactor to produce HSPCs. Employing bioreactors will improve reproducibility and facilitate upscaling towards the desired volumes, as mini-transfusions (1011 RBC, required in phase I trial) could be generated with 3 to 4 threelitre bioreactors. The main challenges to be optimized are specific nutrient and oxygen requirements for each differentiation step, as well as shear stress effects. References [1] WHO. (2022). Blood transfusion. https://www.who.int/news-room/facts-in-pictures/detail/bloodtransfusion [2] Hansen, M., et al. (2019).https://doi.org/10.1002/1873-3468.13599 [3] Wilkinson, A. C., et al. (2019).https://doi.org/10.1038/s41586-019-1244-x [4] Martins Fernandes Paes, B. C., et al. (2017). https://doi.org/10.1007/s10565-016-9377-2 [5] Li, Y., et al. (2017). https://doi.org/10.1088/1758-5090/aa7e9a
