Role of Cord Blood
Each year, tens of thousands of people around the world are diagnosed with a disease that is curable with a bone marrow transplant. Stem cells for the transplant typically come from an adult donor, usually a relative or an unrelated volunteer that is a close enough match by tissue type, also known as human leukocyte antigen (HLA) type. HLA are proteins, or markers, found on most cells in the body which are identified for matching purposes through a specialized test using blood samples from the donor and recipient.
Finding a Match
Only 25 percent of patients who need a bone marrow transplant will have an HLA-identical match in their family (usually a brother or sister) that can safely serve as their stem cell donor. Alternatively, other relatives ("haplo-identical" or 1/2 match donors) could be useful as donors in certain types of transplants.
The vast majority of patients, however, must hope to find a stranger (an "unrelated volunteer") who has a compatible HLA type through the national and international volunteer donor registries. If such a compatible volunteer exists, and he or she is still willing and able to donate stem cells derived from their bone marrow, then the patient may be able to receive the treatment they need.
- The National Marrow Donor Program's (NMDP) Be the Match Registry and the World Marrow Donor Association (WMDA) maintain databases of approximately 30,000,000 registered potential adult donors, and over 700,000 searchable cord blood units (including from our bank).
- However, when a match is found on a registry, only about one-third of these volunteers turn out to be available, willing or able to donate when needed.
- Further, it frequently takes a few months to identify an adult donor from the moment a search is initiated, which is more time than some patients can afford due to the progression of their disease.
- Lastly, ethnic minority patients have an especially hard time finding a matching adult stem cell donor. This is because they represent a smaller percentage of the overall population (i.e., smaller pool of potential donors) and ethnic minorities also tend to have a much greater degree of variation in HLA-type. Caucasian patients find an unrelated donor about 75 percent of the time, whereas African American patients find one only about 25 percent of the time.
Cord Blood Serves Those For Whom No Match Exists
For patients unable to find a suitably matched adult donor, cord blood fulfills a critical need and creates a chance for survival. Most importantly, it does not require a perfect match to be used in a stem cell transplant, which is particularly important when a matching adult donor cannot be found.
In addition, cord blood is collected in advance, tested, stored and ready to use when a patient needs it. Lastly, studies have shown that in many situations cord blood offers several safety and treatment outcome advantages to receiving patients, as compared stem cells from adult donors.
Driven by these and other benefits of cord blood, the worldwide inventory now surpasses 700,000 units, available for any patient in need. Approximately 35,000 stem cell transplants using cord blood have now been performed to date.