Three-hour collection of committed and multipotent hematopoietic progenitor cells by apheresis

Although multipotent progenitor cells have been collected from blood in humans by apheresis in 1- to 2-hour collections, longer-term collections of multipotent progenitor cells have not been reported. To determine whether such collections could be sustained, the authors performed six 3-hour collections on five normal volunteers, processing a mean of 8024 ml of blood. Blood samples were taken at 0, 1.5, and 3 hours, and component samples were taken at 1.5 and 3 hours. Cell counts, differentials, and committed myeloid (CFU-GM), erythroid (BFU-E), and multipotent (CFU-MIX or CFU-GEMM) progenitor cell assays were performed. Collection efficiency for progenitor cells, the number of cells collected divided by the number in the blood processed, did not diminish significantly. The number collected in the second 1.5-hour period resembled the number collected during the first. Circulating numbers did not fall significantly during apheresis. Prolongation of apheresis collections may reliably increase the number of progenitor cells available for eventual hematopoietic reconstitution.