A major problem after autologous or allogeneic stem cell transplantation is prolonged thrombocytopenia. There are several studies published about correlations of the composition of the graft and time to platelet engraftment for autologous transplantation but only a few studies for allogeneic transplantation. In our study, we wanted to find out whether the correlation between the time to platelet engraftment and amount of transplanted CD34(+)CD41(+) cells described previously after autologous peripheral blood stem cell transplantation could be reproduced in the allogeneic bone marrow transplantation setting. We found correlations not only for the number of transplanted CD34(+) cells with the time to leukocyte engraftment (r = -0.32, p = 0.045) but also for the number of transplanted CD34(+)CD41(+) cells and time to platelet engraftment (r = -0.34, p = 0.038), which were both statistically significant. A significant correlation between transplanted CD34(+) cells versus platelet engraftment and transplanted CD34(+)CD41(+) cells versus leukocyte engraftment was not found. The finding that the amount of committed megakaryocyte progenitor cells in the graft is an important predictive factor for platelet engraftment after allogeneic bone marrow transplantation might be the base for future studies of ex vivo expansion of clonable megakaryocyte precursors.
