Searching for a Donor Through the NMDP

Beginning with this issue, Blood & Marrow Transplant Newsletter will feature a series of guest columns contributed by the National Marrow Donor Program.

The National Marrow Donor Program (NMDP), which was founded in 1986, is a nonprofit organization that facilitates marrow and blood stem cell transplants for patients around the world who do not have matching donors in their families. The NMDP's Office of Patient Advocacy (OPA) works with patients to remove barriers to obtaining an unrelated donor transplant. The NMDP Research Program develops and promotes research aimed at increasing opportunities for and improving outcomes of unrelated donor stem cell transplants.

The NMDP maintains the largest, most diverse database of potential volunteer stem cell donors in the world. A search of the NMDP database, which is known as the Registry, automatically accesses the more than 4.5 million volunteer marrow and blood stem cell donors and more than 23,000 cord blood units listed in the United States and Puerto Rico, Israel, the Netherlands, Sweden and Germany. The NMDP also has access to the registries of Canada, Great Britain, France, Switzerland, Spain, Austria, Singapore, Taiwan and Australia.

A search of the Bone Marrow Donors Worldwide (BMDW) registry can also be conducted via the NMDP. The BMDW registry lists donors on 51 registries from 37 countries.

Human Leukocyte Antigens (HLA) Typing

Patients are matched with stem cell donors or cord blood units by comparing their HLA tissue types. HLA is the name given to the system used to identify the unique markers (antigens) on virtually all cells in the body.

In a stem cell transplant, generally six HLA antigens on a person's white blood cells are considered most important for matching: two A antigens, two B antigens and two DR antigens. Recent research has shown that other antigens may also be important. Therefore, some transplant centers test for as many as 12 antigens. A well-matched donor is important to minimize complications during and after transplant.

To determine a person's HLA type, the white blood cells are isolated from a blood sample. Two tests are available to determine a person's HLA type: serological typing and molecular (DNA) typing. Although serological typing is usually sufficient to determine if a patient and a sibling have the same HLA type, molecular typing gives more detailed results. Thus, when searching for an unrelated donor, molecular typing is recommended. Molecular typing enables the NMDP to more quickly and accurately identify matches.

In some cases, transplants can be successful with a less than perfect match. If there is no perfect match, the doctor may want to do a mismatched donor transplant. This may or may not be an option, depending on the patient's age, disease and other factors.

The Preliminary Search
(Registry Review)

A Registry review, also called a preliminary search, is the first step in the search process. A Registry review can be requested by a transplant center (hospital) that is part of the NMDP Network, or by the patient's doctor (referring physician).

A Registry review is a one-time review of all the volunteer donors in the computer system that match the patient on the day of the search-a snapshot in time of the potential donors available that day. It is important to note that it is NOT an on-going search to identify a matched unrelated donor for the patient. New donors are added to the Registry daily, and a Registry review can be repeated as often as desired to get updated reports. Preliminary search results are reported to the patient's physician within 24 hours.

A Formal Search

If a review of the NMDP Registry identifies potential donors, a formal search may be requested. A formal search request must come from an NMDP-approved Transplant Center. A list of NMDP-approved Transplant Centers is available online at www.marrow.org/NMDP/nmdp_network.html or may be requested from the Office of Patient Advocacy (see end of article).

A Transplant Center doctor starts a formal search by requesting that one or more potential stem cell donors or cord blood units undergo more testing. If the patient search report shows potential HLA A, B and DR matched donors, the doctor may ask for confirmatory typing to find the best possible match. If the potential donors have not undergone molecular typing, the transplant center may request molecular typing of some donors.

When a formal search is requested, the Office of Patient Advocacy sends the patient a letter and information booklet about the search process. It is important that patients maintain regular contact with the Transplant Center regarding the progress or status of the search.

Formal searches are updated each night. If new matched donors become available, the Transplant Center is notified the next morning. Formal searches remain active on the NMDP's computer system until the Transplant Center officially cancels the search.

Each Transplant Center has its own criteria for what is a suitable match between the patient and the donor. The match criteria may also vary depending on the source of stem cells (bone marrow, peripheral blood stem cells or cord blood).

Donor Education

When a possible donor is identified, he or she is contacted by the NMDP, often to do more typing to confirm that the donor is the best match. If the Transplant Center selects the donor as a good match, the donor's blood is tested for infectious diseases, and the donor is given a health history and physical to check for any risks that could endanger either the patient or the donor during transplant. At every step, the donor is educated about what is involved in donating and has a chance to confirm that he or she is still committed to donate marrow or blood stem cells.

How Long Will It Take?

The search for an unrelated donor can take as little as a few weeks or as long as several months, depending on the urgency of the search, the uniqueness of a person's HLA type (more unique HLA types may be more difficult to match) and the source of the stem cells (cord blood units are often available more quickly than marrow or blood stem cell donors).

To ensure progression of the donor search process, the NMDP Office of Patient Advocacy has case managers who work with patients and their physicians throughout the search process. Case managers have backgrounds in stem cell transplantation, nursing, advocacy, crisis counseling, insurance and financial needs analysis. Patients and their families are encouraged to contact an OPA case manager at any time with questions about the search process.

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