Does continuous flow apheresis influence viability in allogeneic hematopoietic stem cell harvest?

One of the important clinical variables determining the success of hematopoietic stem cell transplantation is the number of viable CD34+ stem cells transfused to the patient. G-CSF mobilized peripheral blood stem cells from 17 healthy donors were collected by continuous flow apheresis. The median (range) proportions of early apoptotic (Annexin V-FITC(pos)/7-AAD(neg)) and viable (Annexin V-FITC(neg)/7-AAD(neg)) CD45(dim)CD34+ stem cells were 1.5 (0.9-3.7)% and 97.7 (82.8-100)% in the peripheral blood before apheresis and 2.6 (0.8-7.9)% and 97.3 (91.9-99)% in the apheresis products, respectively. Despite an increase in the number of apoptotic cells among all cell compartments, this was statistically significant only in CD34+ cells and granulocytes. The majority of the cells still retained their viability.