Finding a Match
Several studies indicate that cord blood transplants do not need to be as perfectly HLA-matched to the recipient as bone marrow transplants do. However, patients have a better chance to survive and regain health if the cord blood graft is better matched (6/6 or 5/6) and provides cell doses of 20 million nucleated cells per kg or more.
Public Search (Open to Everyone).
Patients and their families can conduct a Public Search to find the number of possible matches at the low resolution level of HLA typing. This search is "preliminary" because it does not take into consideration all the details that a "formal" search does.
Physicians and Transplant
Coordinators can submit
formal Search Requests (based on high or low resolution HLA typing) online.
Transplant Center Formal Search.
Transplant Centers can submit Search Requests either directly to NCBP or through NMDP's Single Point of Access. Direct Search Requests can be made through Fax, using Search Request forms provided by NCBP or through our new WebSearch site, currently being deployed (click here to see the NCBP WebSearch Press Release). When a Search Request is made, the NYBC's National Cord Blood Program returns a Preliminary Match Report to the Transplant Center. This Report lists individually all cord blood units available sorted by the level of HLA match and total nucleated cell (TNC) dose (cells/kg of patient's weight). Because some patients still may not have high resolution HLA typing, their matches may be based on the low resolution typing submitted, unless the Transplant Center requests high resolution typing at the time of confirmatory typing of the patient. High resolution DRB1 type of each unit is included in the report, however.
A special type of Search was instituted by NCBP to satisfy the requirements of the Single Point of Access (SPA). The implementation of SPA was mandated by the Stem Cell Act of 2005 as a method to facilitate Unrelated Donor Search for Transplant Centers, by avoiding the need to address Search Requests to all the different Bone Marrow Donor Registries and Cord Blood Banks. Instead, a single Search request submitted to the SPA will retrieve all potential matched cord blood units from all the US Cord Blood banks. To that effect, NCPB (which is an independent Bank, not belonging to the NMDP) has developed a unique IT system in collaboration with the SPA: all search requests submitted to the SPA are transferred electronically to the NCBP and run through the NCBP database. The resulting matched units are transmitted back to the SPA (within 8 seconds) so they are included in the Report that the SPA sends to the Transplant center with all potential matches. In addition, NCBP answers directly to the Transplant Centers about the NCBP matched units with a separate Report.
Furthermore, the advantages of a fully implemented database, including information concerning the donor history, infectious disease tests, family data, etc., rapidly expanded the SPA so that it can also provide transactional possibilities (i.e., interactions between the SPA and the Transplant centers). Thus, the SPA in the US has become not just a search engine, but the mechanism for the selection, evaluation and final choice of a cord blood graft.
Cord Blood Unit Match Reports.
When the Transplant Center wants to select a cord blood unit, or units, for transplantation, the Transplant Coordinator requests Match Reports on each unit the physicians want to consider. An individual Match Report gives detailed information about the cord blood unit, including number of total nucleated and CD34+ cells, ABO and Rh blood groups and results of other laboratory tests. NCBP staff also review the medical history records, assess potential risks for infectious or genetic diseases and assign donor eligibility, as required by FDA. Furthermore, NCBP staff review all unit information, before the report is released, to identify and report on any details that might affect the quality of the unit. When the unit is requested via NMDP, the data is reported to the NMDP database through IT mechanisms; when requested directly, this is done through either, fax or our own WebSearch (in the process of full implementation).
Confirmatory HLA Typing.
When one of our units may be selected for cord blood transplantation, we request a blood sample from the patient, if possible, to confirm the patient's HLA type in our own laboratory. Confirmatory HLA typing of each cord blood unit is also completed using blood in a segment of tubing attached to the bag of the frozen unit. This procedure both confirms the HLA type and assures that the unit and its originally typed sample were correctly labeled during processing, that is, there were no errors in identification. Confirmatory HLA typing is done at high resolution level by DNA sequencing and is generally available within 3 days (less than 24 hours in an emergency). Thus, final selection of the cord blood unit is based on the most rigorous HLA typing possible. Because of its key importance, we do not charge extra fees for confirmatory typing of either the patient or cord blood.
Aliquots Available for Special Testing.
Transplant Centers can request aliquots of stored plasma, nucleated blood cells or DNA for special testing or we can send samples to a specific laboratory for special testing, at the Center's discretion. Centers have requested samples to measure enzyme levels for specific genetic diseases, for example, or for infectious agents that are not part of routine testing.
Preliminary data indicate that cord blood units with a 6/6 match to the patient's HLA type have the best outcomes even with lower TNC doses. When the match is 5/6 or less, TNC dose matters more. In these cases, we, and most physicians recommend a TNC dose of at least 20 million TNC per kilogram of the patient's body weight. At present, there is no evidence that the outcome of the transplant is further improved when the TNC dose is greater than 100 million per Kg.
NCBP staff assist in selecting the most appropriate unit available for the patient, depending on the HLA match and cell dose. NCBP physicians, scientists and HLA experts are available for consultation. If necessary, we will provide special analyses of transplant outcome data to help make a decision in selecting a cord blood unit.
What Happens Next?
When a cord blood unit is requested for shipment, NCBP asks for a copy of the patient's signed consent form and asks the transplant physician to sign a Request Form documenting that he or she has reviewed the information provided and approves the transplant. We require documentation of IRB approval of the transplant protocol and the patient's Informed Consent because we operate under an FDA IND exemption. All records of the unit and patient are reviewed by NCBP Medical Director, who must give final approval to release the unit. NCBP staff then work with Transplant Center staff to schedule shipment of the unit to the Transplant Center.
Double unit cord blood transplants
The total nucleated cell dose (TNC cells contained in the cord blood unit divided by the patient’s weight) is very important for the results of transplantation. The dose depends on the number of cells collected, as well as the size (weight) of the recipient patient. Although most cord blood collections contain enough cells for pediatric patients, they may not be sufficient for adults. To overcome this limitation, physicians at the University of Minnesota started using two cord blood units for large patients, when a single, sufficiently large unit was not available. The patients outcomes from these studies were encouraging and now many patients receive “double unit cord blood grafts” i.e., two cord blood units from different donors, when one large enough cannot be found, as a way to increase the total number of cells.