Red blood cell evolved a mode of red blood cell development substantially different from the mammalian norm. Overall, mammalian red blood cells are remarkably flexible and deformable so as to squeeze through tiny capillaries, as well as to maximize their apposing surface by assuming a cigar shape, where they efficiently release their oxygen load. Red blood cells in mammals are unique amongst vertebrates as they do not have nuclei when mature. Red blood cells of mammals cells have nuclei during early phases of erythropoiesis, but extrude them during development as they mature; this provides more space for hemoglobin. The red blood cells without
Genetically engineered blood Genetically engineered blood Genetically engineered blood is blood that has been modified for therapeutic or other purposes. Genetically modifying red blood stem cells allows them to produce specific therapeutic proteins on the surface or inside the cell. The stem cells are taken from mammalian bone marrow and are modified in culture. Before they become mature, mammalian red blood cells eject their genetic material. Culturing cells that produce a new protein of interest requires only a few weeks. Using the sortagging protein labeling technique, the researchers used the bacterial enzyme sortase A to establish a strong chemical bond between the surface