Cord blood: Spotlight on the processing step

Cord blood (CB) can be stored processed or un-processed. The advantage of applying a processing step to the cord blood units (CBUs) for cord blood banks (CBBs) is that the volume can be reduced by depletion of plasma and sometimes also by reduction of red blood cell (RBC) number. This decreases the associated costs for storage. Another advantage is the reduction of the quantity of cryopreservation solution in the final product. As the RBCs tend to burst during the freezing and thawing step the decrease in RBC numbers reduces the possibly harmful cellular debris and free hemoglobin released by burst RBCs into the CBUs. However processing can potentially cause also a loss of the wanted cells, like the stem cell compartment or cause stress to these cells. Thus, the optimal processing system reduces volume and RBCs while at the same time leaving the wanted cells like the stem cell compartment with its hematopoietic as well as non-hematopoietic stem cells unaffected. Hematopoietic stem cells are mainly used as a source for transplants to reconstitute the blood forming cells while non-hematopoietic stem cells can support the hematopoietic stem cells in the transplant setting but are potentially useful also for other regenerative medicine or immune modulatory purposes. Many CBBs today use a processing step instead of storing the CB un-processed just by the addition of cryopreservation solution. Different processing systems exist which often employ a centrifugation step for processing of the CBUs. In addition, we described recently a manual system, CellEffic CB, which employs a filtration step eliminating the need for centrifugation and thus any machines and its associated costs. We will highlight here recent development in the cord blood industry and how the new filtration system can contribute to this industry.