World map of family banks
- What questions should parents ask a Family Bank about collecting cord blood?
- What instructional tools are provided for the physician and delivery staff?
- Will the cord blood company actively contact the labor and delivery staff for you -- or are parents responsible for keeping them informed and coordinated?
- What collection method do they use: gravity drip or blood draw?
- Is the collection blood bag sterile, both inside and out, so that it can be used in the operating room for a C-section?
- Do they provide the option of collecting additional stem cells from the placenta or tissue of the umbilical cord?
- Processing: How is cord blood processed before storage?
The three main components of cord blood, like any blood collection, can be separated by weight: the heaviest layer is the red blood cells (RBC), the lightest is the plasma (a clear white liquid), and in the middle is a pinkish layer called the "buffy coat" which contains the white blood cells (WBC), including stem cells. When banks process the cord blood, the final separated component that goes into storage is the buffy coat, even though only about 1% of the cells are actually stem cells. There is no procedure to separate out the stem cells alone.
The vast majority of blood processing methods rely on the different density of the three main blood components. They can be separated by sedimentation, or by centrifuge, or by a combination of the two techniques. The procedure can be performed manually by trained technicians or by automated machine.
- How much blood and stem cells does a typical umbilical cord hold?
The median size of cord blood collections in family banks is 60mL or 2 ounces. That small volume of liquid corresponds to 470 million Total Nucleated Cells (TNC) or 1.8 million cells that test positive for the stem cell marker CD34. Thus, most healthy full-term babies have over a million blood-forming stem cells in their umbilical cord blood. By comparison, most public cord blood banks will only keep collections that are much bigger than average, and throw out the donations that are below a threshold of a billion TNC, corresponding to a blood volume of about 90-100 mL or 3 ounces.
Sun, JJ et al., Transfusion Sept. 2010; 50(9):1980-1987