Blood Storage - The Process Explained

Some people will choose cord blood banking and won't feel the need to understand the actual process of banking the cord blood. Others, however, will want to understand exactly what the bank is going to do and how they will do it. Here is an explanation of how the banks deal with the cord blood and how they store it after the retrieval.

A few banks freeze the blood whole, but most banks process it. There are two stages to the processing - Volume Reduction and Separation.

Volume Reduction

The volume reduction is either done by sedimentation or by spinning in a centrifuge. The blood components are then separated so that the red cells are on the bottom, the plasma is on top and the white blood cells are in the middle. The white blood cells look like a pinkish layer and are called the "buffy coat" and this is where the stem cells are also stored. The white blood cells with the stem cells are then stored in bags by most public banks.


Some cord blood banks continue with this process and use more centrifuge spinning of the white cells. One of the protocols for doing this is called "Ficoll-Hypague" density gradient centrifuge. This further separation reduces the size of the collection to a very small amount of a few milliliters. This can then be stored in vials.

When you, as a parent, receive a follow-up lab report explaining how many billions of cells you have stored, it's important to know that most of those cells aren't stem cells. They are counting all of the stored cells, of which only 1-2% is actually stem cells.

Is The Separation Process Necessary?

The separation of the cells certainly adds to the laboratory costs, and some people argue that there is no reason to go through this process before storing the cord blood. The earliest cord blood transplants did use whole blood and didn't separate out all of the different types of blood. However, it has now become standard practice in the medical community to separate out the red cells prior to freezing, and you won't find many cord blood banks to counter this. Even if it costs a bit more, it is the norm in the business and the research does seem to indicate that it helps, should you ever need the cord blood later.

Are Stem Cells Lost During This Process?

Certainly, some stem cells will be lost during this process. It is a large debate, however, to pinpoint what percentage of stem cells are lost when skimming off the buffy coat. Every company will claim that their method is the best and that they lose the least amount of stem cells. Studies have indicated that there is not a great deal of difference between the volume of stem cells in cord blood that has been stored without processing, and that stored after processing. This would lead one to believe that not too much stem cell material is lost in the processing.


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