Ultra-high-yield manufacture of red blood cells from hematopoietic stem cells

Provision of a safe and secure supply of transfusible red blood cells (RBC) is a major global health challenge, and it has been proposed that manufactured RBC could help to alleviate the constraints of the current donor system. Several substantial challenges must be addressed for this approach to be feasible. At the most basic level, this relates to the large quantities of cells that are required: is there sufficient biological capacity, and is it possible to produce RBC using large-scale processes? While it has been demonstrated that, in principle, up to 5 units of RBC could be generated from a single donation of umbilical cord blood (UCB) hematopoietic stem cells, such yields are insufficient to supply demand and existing culture methods are unsuitable for large-scale manufacture. Given the capacity of the hematopoietic system in vivo, we reasoned that an optimized process should give rise to much larger quantities of RBC than previously reported. We successfully developed a robust ultra-high-yield RBC expansion process capable of producing over 500 units of RBC per UCB donation using fully defined culture medium. We obtained near-pure populations of reticulocytes with an enucleation frequency of >90%, mean cell hemoglobin content of 30.8pg/cell, and mean cell volume of 133fL. We also show that RBC can be efficiently produced in agitated bioreactor systems, demonstrating that no fundamental barriers exist to the manufacture of RBC using large-scale approaches