Umbilical cord blood processing: volume reduction and recovery of CD34+ cells

One of the main problems for the establishment of umbilical cord blood (UCB) banks is the storage space needed for the frozen samples. The aim of this study was to find a method of reducing the volume of UCB units without major losses of the haematopoietic progenitor-CD34+ cells. The UCB was collected into a triple blood bag system, in which the anti-coagulant had been previously adjusted. The blood bag was first centrifuged for red cell depletion followed by a second centrifugation for plasma reduction. At this point, the main bag containing the white blood cell (WBC) rich fraction "buffy coat' (BC) and the "waste bag' were sealed and detached. Haematologic cell counts and CD34+ cell quantification were done in whole blood and in the isolated fractions. The average volume of the 19 UCB samples processed was 103 ml. Separation by centrifugation led to a mean volume reduction of 56% with red cell depletion of 59%. The white blood cell recovery was of 72% with a significant CD34+ cell recovery of 87%. This seems a promising method for cord blood volume reduction and enrichment of CD34+ cells.