Can every patient be mobilized?

There are several ways to mobilize hematopoietic stem cells for autologous and allogeneic hematopoietic stem cell transplant by manipulating the bone marrow microenvironment. Granulocyte colony-stimulating factor (G-CSF) and chemotherapy have been commonly used to mobilize stem cells, but several new agents, such as the CXCR4 inhibitor plerixafor, inhibit stromal-stem cell interactions to improve stem cell yield. The minimum threshold for engraftment is 2 × 106 CD34+ cells/kg, but it has been shown that higher CD34+ stem cell dose, such as 5 × 106 CD34+ cells/kg, is associated with improved survival. Efforts to increase stem cell yield remain important to improve outcomes.