Biomedical Engineering Reference
In-Depth Information
Chapter 14
Cord Blood Cell Cryopreservation
If you want to make an apple pie from scratch, you must first
create the universe.
- Carl Sagan
Before the umbilical blood is frozen, it will first be introduced to a solution to help
prevent it from being damaged while frozen. This solution is referred to as the cryo-
preservation solvent or cryoprotectant [
1
]. Once the blood has received this, it will
begin to slowly freeze. Freezing it gradually is used as another preventative mea-
sure in guarding the cells against damage. Once the blood is frozen to a temperature
of −96°C, it is transferred to a permanent storage freezer where it will remain frozen
through the use of either liquid or vapor nitrogen. There are two different types of
freezers commonly used in the preservation of cord blood stem cells. The first is the
“BioArchive” freezer. This machine not only freezes the blood, but also inventories
it and manages up to 3,626 blood bags [
2
]. It has a robotic arm that will retrieve the
specified blood sample when required. This ensures that no other samples are dis-
turbed or exposed to warmer temperatures. The second freezer system is the
“Dewars” which is the most commonly used freezing system in the USA [
2
] . This
unit is basically a well-insulated container with a lid. Because the lid needs to be
opened every time a sample goes in or out of the freezer, there is a risk of the other
samples being compromised. However, to help guard against this, temperatures on
these freezer units are vigorously maintained and monitored. Cord blood cell sam-
ples are stored either in bags or in vials inside the freezers. Most cord blood banks
will use only one type of storage since the bags or vials need to be evenly spaced on
the racks inside the freezer. Therefore, the racks tend to be equipped to accommo-
date only one type of storage container. However, a few banks do use both bags and
vials to store the cord blood. They have separate freezer units for each type of storage.
