The challenge of growing enough reticulocytes for transfusion

Abstract

There is considerable research interest in manufacturing blood products for patients using a variety of different cellular sources, including stem cells (embryonic, cord and adult), induced pluripotent stem cells and erythroid cell lines. Red blood cells (RBC) represent a particularly attractive regenerative medicine blood product due to the absence of the nucleus in the final cellular product meaning that they pose a minimal risk in terms of potential for transformation in the recipient, and allogeneic red cell transplants have been given for many years. The number of RBC required in a standard adult therapeutic dose (2 × 10 12 ) is intimidating, but encouraging progress has been made in RBC production under good manufacturing practice from adult stem cells. Already, a cultured RBC (cRBC) mini‐transfusion has been conducted in a single volunteer illustrating that the cultured cells can survive in circulation and exhibit no adverse reaction. We must now demonstrate that cRBC are equivalent to the RBC produced naturally in donors by testing laboratory grown blood in multiple volunteers, with the possibility of showing that these cRBC have prolonged survival due to being freshly made reticulocytes. Work is also required on increasing the yield and scaling up cRBC manufacturing to generate clinical quantities of cRBC in a more efficient and cost‐effective ways.