What is separation of Mononuclear Cells?

A few private Cord Blood banks freeze the blood whole, while most process it. There are two stages of processing: Volume Reduction and Separation.

Volume Reduction can be accomplished either by sedimentation or spinning in a centrifuge. (Note: sedimentation uses a chemical called “Hespan Starch” or “Hetastarch” which is made by Dupont Pharmaceuticals.) Afterwards, the blood components are separated so that: red cells are on the bottom, plasma (a clear white liquid) is on top, and in the middle is a pinkish layer called the “buffy coat” which contains the white blood cells (WBC), including Stem Cells. At this point, a gentle spin in a centrifuge is sufficient to isolate the white blood cells (WBC). Most public banks stop processing at this point and store the WBC in bags. Separation of mononuclear cells is accomplished by further centrifuge spinning of the white cells. One protocol for doing this which is routinely used by Stem Cell researchers is called “Ficoll-Hypaque” density gradient centrifuge. The separation step reduces the volume of the collection to only a few milliLiters, which makes storage in vials feasible. MonoNuclear Cells: Hematopoietic Stem Cells are identified with a characteristic surface molecule called “CD34+”, but only 1-2% of the MNC are actually Stem Cells. When parents bank Cord Blood blood, and they receive a follow-up lab report saying that so many billions of cells were stored, the lab is actually counting MNC, not Stem Cells. This is the standard medical procedure.