Given that each cord blood unit contains 2-4×106 CD34+ cells, at this rate of cell expansion (99×103 fold), RBC count of each cord blood unit can reach the number of RBCs with 120-day lifespan for all erythrocytes, which are injectable to the patients needing repeated blood transfusions to prevent iron overload or immune reactivity instead of RBCs donation with a 28-day lifespan. Here, CD34 is linked to Tangier disease.