Bone marrow transplantation: how important is CD34 cell dose in HLA-identical stem cell transplantation?

A recent analysis of Fred Hutchinson Cancer Research Center data has been undertaken to investigate the association of infused CD34 cell dose with various clinical outcomes after HLA-identical transplantation. Separate assessments for unrelated vs related donors and the use of bone marrow or mobilized G-CSF stimulated peripheral blood mononuclear cells (G-PBMC) have been incorporated. The three primary findings are: (1) Higher CD34 dose results in better neutrophil and platelet recovery in all settings. (2) Higher CD34 doses (8 x 10(6)/kg) are associated with the development of more chronic graft-versus-host disease when using related G-PBMC. (3) Higher CD34 dose is correlated with improved survival after unrelated donor bone marrow transplantation. These data suggest that the CD34 content of a graft can have a significant impact on clinical outcome after allogeneic transplantation, but defining an optimal dose is dependent on both the type of donor and the stem cell source.