Must cord blood be processed before storage?
The earliest cord blood transplants were performed with whole cord blood. Thus, it is not absolutely necessary to process cord blood in order to save patient lives. There has never been a prospective randomized trial to compare transplant patient outcomes with cord blood that had been stored whole versus processed.
Today most cord blood banks, both public and private, process cord blood to remove both the plasma and the red cells, and cryo-preserve the remaining "buffy coat" that holds both white blood cells and stem cells.
Many doctors consider it important to remove red blood cells before preserving cord blood stem cells, and we have a fact sheet on red blood cell depletion. The reason to remove the red blood cells is because they tend to burst during freezing, which releases iron from hemoglobin that can be toxic. The alternate to removing the red cells before freezing is to wash any broken cells out of the cord blood unit upon thaw.