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Canada has had a public network accepting cord blood donations in Quebec since 2004 and is expanding to cover the nation in 2013.Read more >>
- What is HLA Type and how is it used?
The term "HLA" is short for Human Leukocyte Antigens, and these are proteins in the immune system that determine whether a patient will react against a donor transplant. A very good basic tutorial about HLA types is on the Stanford Website, and the national Be The Match program (aka NMDP) has more info on the role of HLA type in transplants of stem cells from bone marrow or cord blood.
Briefly, there are 6 HLA types that are important for stem cell transplants: in a bone marrow transplant the patient and donor must match at all 6 (100% match), whereas a cord blood transplant is just as effective at curing patients with only a 4 out of 6 match (67% match) between donor and patient. This is the reason that donations to the national cord blood inventory managed by NMDP are so important to help patients who come from minority or mixed racial backgrounds.
The HLA type of cord blood is always measured by public banks, and then the type is listed on a registry that can be searched by patients seeking a transplant. Family banks typically do not measure the HLA type at the time of banking, because it is an expensive lab test and and can always be checked later from a testing segment of the stored cells.
- If I banked privately for one child, do I need to do it for additional children?
All the reasons that you banked for the first child are still valid for additional children.
1. If you want the baby to have the option of using his/her own cells, then you need to bank them.
2. If you are banking to cover siblings, then the ability to use cord blood from one child for another depends on whether they have matching HLA type. Two full siblings have a 25% chance of being a perfect match, a 50% chance of being a half match, and a 25% chance of not matching at all. For a cord blood transplant, donor and patient must match at 4 out of 6 (67%) HLA types. The more siblings with banked cord blood, the more chance that they cover each other for possible transplants or other therapies for which sibling stem cells are accepted.
Odds of sibling match are based on haplotype inheritence: that the child will receive 3 HLA types as a group from each parent.
- How much cord blood is needed for a transplant?
The crucial thing is not the volume of the cord blood collection, but the number of stem cells it contains. Transplant doctors develop recommendations based on the Total Nucleated Cell count, or TNC, because it is the easiest measure to reproduce between different labs. For treating cancer, the transplant dose should be at least 25 million TNC per kilogram of patient body weight (1 kilogram equals 2.2 pounds). The average cord blood collection holds 8.6 million TNC per mL. Thus, the optimal transplant dose requires harvesting:
1.3 mL of cord blood for every pound of patient weight, -or-
2.9 mL of cord blood for every kg of patient weight
However, as more transplant centers are adopting the practice of giving adult patients "double cord blood transplants" with two cord blood units, it is less critical for both units to have adequate cell dose.
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