Successful ex vivo production of RBCs from human umbilical cord blood (hUCB) for transfusion would relieve limitations in the blood donation system, but remains impractical due to the current costly and inefficient suspension culture systems. We previously developed a 3D hollow fibre bioreactor to promote long-term, scalable expansion of red cells using smaller volumes and physiological cytokine concentrations. We extend these studies to further characterise the hematopoietic microenvironment for erythroid expansion and maturation...