What is the optimum number of CD34+ peripheral blood stem cells for an autologous transplant?
There is a wide variation in the number of CD34+ cells infused for an autologous transplantation. While the minimum number of hematopoietic stem cells for a successful transplantation has been established, there is no definite information on the optimum number or the maximum number of stem cells. It is generally agreed that a minimum dose of 2.5 x 10(6) CD34+ cells is necessary for successful engraftment. Although engraftment of neutrophils and platelets is achieved at that dose, it is delayed and is also negatively influenced by other factors. Reinfusion of 5.0 x 10(6) CD34+ cells results in prompt engraftment of all three cell lines and should be the preferred target. At least one study indicated that a very large number of cells (>15 x 10(6) CD34+ cells) resulted in further improvement in engraftment, decreased packed red blood cell and platelet transfusion, shorter hospitalization, and overall decreased costs. In contrast, a few studies showed that reinfusion of a large number of C
