We’ve all heard the stories about the urgent need for blood donors and many of us or our loved ones have benefited from a blood transfusion. In the US alone, there are 21 MILLION transfusions of blood products per year. For years the production of blood from stem cells has been an invention “just around the corner” without becoming a reality. Two recent Nature publications in the past month give new hope that the shortage of blood will come to an end.
One group of researchers used human pluripotent stem cells to form hematopoietic stem cells, which can become any cell type found in blood . They achieved this by screening a few dozen transcription factors, which are proteins that regulate the expression of certain genes. They identified 7 critical transcription factors and used these to form hematopoietic stem cells, which could be used to produce red blood cells and the other cell types found in blood.
The second paper produced hematopoietic stem cells from mouse endothelial cells . Endothelial cells are common cell type found lining the inner surface of blood vessels. This research team reprogrammed these endothelial cells by using a viral vector to temporarily express certain transcription factors. The result was a direct conversion of endothelial cells into hematopoietic stem cells.
These two discoveries may pave the way for an unlimited supply of blood in the future. It might be possible to grow your own blood from your cells or to create a large supply of universal donor blood. It is still not clear which approach will work best in the real world, but we are that much closer to a world without blood shortages.
 Sugimura R, Jha DK, Han A, Soria-Valles C, da Rocha EL, Lu YF, Goettel JA, Serrao E, Rowe RG, Malleshaiah M, Wong I, Sousa P, Zhu TN, Ditadi A, Keller G, Engelman AN, Snapper SB, Doulatov S, Daley GQ. Haematopoietic stem and progenitor cells from human pluripotent stem cells. Nature 2017.
 Lis R, Karrasch CC, Poulos MG, Kunar B, Redmond D, Duran JGB, Badwe CR, Schachterle W, Ginsberg M, Xiang J, Tabrizi AR, Shido K, Rosenwaks Z, Elemento O, Speck NA, Butler JM, Scandura JM, Rafii S. Conversion of adult endothelium to immunocompetent haematopoietic stem cells. Nature 2017.