Finding a Bone Marrow or Stem Cell Donor

If you need a transplant using bone marrow or stem cells from a donor, there are two options: a family member or an unrelated donor.

Printer-friendly version

If you are having a transplant using your own blood stem cells (an autologous transplant) you will not need to search for a stem cell donor.

If you are having a transplant that requires cells from a donor (allogeneic transplant) your transplant team will work with you to find a suitable donor. A donor search is not a process you initiate on your own.

The donor's blood stem cells must have similar genetic markers as yours. These markers are called human leukocyte antigens or HLA.

Human Leukocyte Antigen Test (HLA)

Since you inherit your HLA type from your parents, a brother or sister with the same biological parents is the most likely candidate to be your donor.

Approximately one-third of patients in the U.S. have a sibling who can serve as their donor. 

Your doctor may also ask other family members to be tested, although the likelihood that they will be a perfect match is small.

Determining whether a family member is a match requires a DNA test.

  • This can be done by swabbing some cells from the inside of the cheek or by taking a blood sample.
  • The sample is then sent to a special DNA testing laboratory.
  • If the person is an HLA-match, a detailed physical examination and health history will be done to determine if he or she is healthy enough to be a donor.

See Being a Related Donor for more details.

How to Find an Unrelated Bone Marrow, Stem Cell or Cord Blood Donor

If a family member cannot serve as your donor, your transplant center will begin a search for an unrelated donor.

  • The search will include adult volunteer donors.
  • If your transplant center performs umbilical cord blood transplants, a search of the international inventory of cord blood units will be conducted as well.
  • Potential donors' HLA type will be compared to yours to determine if they would be a good donor for you.

Be The Match® coordinates unrelated donor searches in the U.S. Through its partnership with donor registries throughout the world,

Be The Match® provides access to nearly 41 million volunteer donors and more than 811,000 cord blood units worldwide.  

Depending on your HLA type, the preliminary search may identify just a few or many potential matches. Your transplant doctor will select the most promising candidates for further testing.

Mismatched Bone Marrow and Stem Cell Donors

If a perfect match cannot be found for you, your doctor may suggest you use a mismatched donor. Mismatched donor transplants are very common, particularly for people with rare HLA types, and can lead to long-term success.

Your doctor may suggest a haploidentical transplant. A haploidentical transplant is a transplant using cells from a related donor, such as a parent or child, who only half matches your HLA type. Use of haploidentical transplants has made it possible to enable many more patients to undergo a bone marrow or stem cell transplant.

Other Criteria When Choosing a Bone Marrow, Stem Cell or Cord Blood Donor

Although HLA type is the most important consideration when choosing a suitable donor, your doctor will also take other factors into consideration including:

  • age (younger is usually preferred over older)
  • gender (male is often preferred over female)
  • if the donor is female, the number of times she has been pregnant
  • history of infection, particularly with the cytomegalovirus (CMV)
  • weight
  • health history

(To view this page in Spanish click here)

Next Page:  Being a Related Donor

Updated August, 2023