Initial cord blood unit volume affects mononuclear cell and CD34+ cell-processing efficiency in a non-linear fashion.

Background Aims: Umbilical cord blood (UCB) is a source of hematopoietic stem cells that initially was used exclusively for the hematopoietic reconstitution of pediatric patients. It is now suggested for use for adults as well, a fact that increases the pressure to obtain units with high cellularity. Therefore, the optimization of UCB processing is a priority.
Methods: The present study focused on parameters influencing total nucleated cell (TNC), mononucleated cell (MNC) and CD34+ cell (CD34C) recovery after routine volume reduction of 1553 UCB units using hydroxyethyl starch-induced sedimentation with an automated device, under routine laboratory conditions.
Results: We show that the unit volume rather than the TNC count significantly affects TNC, MNC and CD34C processing efficiency (PEf), and this in a non-linear fashion: when units were sampled according to the collection volume, including pre-loaded anticoagulant (gross volume), PEf increased up to a unit volume of 110-150 mL and decreased thereafter. Thus units with initial gross volumes < 90 mL and > 170 mL similarly exhibited a poor PEf.
Conclusions: These data identify unit gross volume as a major parameter influencing PEf and suggest that fractionation of large units should be contemplated only when the resulting volume of split units is > 90 mL.