Defining a Therapeutic Dose of Peripheral Blood Stem Cells

Peripheral blood stem cells (PBSC) are now used extensively to provide rapid and durable hematopoietic reconstitution following supralethal myeloablative therapies. A major clinical issue is the quantitation of the cells responsible for reconstitution. We review here published reports of transplants using the measurement of mononuclear cells and granulocyte-macrophage colony-forming units (CFU-GM) to quantitate PBSC. In addition, we present data from three institutions where hematopoietic recovery is correlated with doses of CFU-GM or CD34⁺ cells. These data suggest doses of 20 X 10⁴ CFU-GM or 2 X 10⁶ CD34⁺ cells/kg body weight that provide rapid engraftment of neutrophils and platelets.