SCT Donor Evaluation
Donors for stem cell transplant can be family members such as siblings for matched related transplant, parents or siblings for haplo-identical transplant, or unrelated donors either via living adult volunteers (bone marrow or peripheral blood stem cells) or umbilical cord blood units. The important aspects of evaluation of potential donors are related to determining any potential infectious risks, determining health of the donor and ability to undergo either surgical harvest of bone marrow or a procedure in which peripheral blood stem cells (PBSCs) are isolated through an intravenous connection to a machine (leukapheresis). For cord blood units, the health of the mother and infant as well as any potential other medical risk factors are carefully taken into consideration before releasing these units to the international inventory.
Evaluation of Stem Cell Donors/Sources includes the following at a minimum
Infectious Disease Testing is standardized for the most part and includes:
Ebstein-Barr Virus (EBV)
HTLV 1 and 2
Hepatitis B and C
HLA type with a minimum of 6 loci for cord blood units and 8 loci for marrow or PBSCs. Some centers use high-resolution typing for up to 10-12 loci for cord blood, bone marrow, and PBSCs. HLA matching is discussed in a separate section.
Blood Type of donor and recipient
Physical exam and full medical history
Anesthesia evaluation if applicable
Travel to areas associated with high infection risk is also taken into consideration
This evaluation is done with blood tests and must be performed no more than 30 days prior to the date of collection of stem cells.
For cord blood this evaluation is done on both the mother and the cord blood unit.
History of high-risk behaviors such as intravenous drug use and multiple sexual contacts is also taken into consideration for adult volunteer donors
Tattoos and piercings are also considered as potentially increasing the risks of infection associated with donation of marrow or PBSCs
A physician that is independent of the patient's SCT team must evaluate sibling donors under the age of 18 to ensure that they are able to consent willingly and understand completely the marrow or PBSC harvest procedure. The SCT team then will do a pre-operative (or pre-pheresis) evaluation with history and physical and will do another evaluation post collection of stem cells, usually on post-operative day 1 or 2.
For cord blood units, any significant genetic, malignant, or other serious post-natal condition is supposed to be reported to the cord bank for any living infant/child, so that this information can be promptly communicated to the SCT team caring for the recipient and consideration can be given for monitoring or potential treatment of the cord blood transplant recipient.
Donor Selection Process
Donor Selection Process
Donor selection only applies to those patients undergoing allogeneic stem cell transplantation. (Autologous transplantation uses the patient’s own stem cells.)
In the donor selection process, a number of factors are considered and a few tests are performed to determine a match.
Human Leukocyte Antigen – HLA
Human leukocyte antigen (HLA) typing is used to match patients and donor for blood and marrow transplant. HLA are proteins – or markers – found on most cells in the body. The body’s immune system uses these markers to recognize which cells belong to the body and which do not. A close match between the patient’s HLA markers and the donor’s HLA markers can reduce the risk that the patient’s body will attack the donor cells or that the donor cells will attack the patient’s cells after the transplant.
A well-matched donor is important to the success of the transplant. There are many HLA markers. The best case scenario is that 10 out of 10 HLA markers will match. These requirements are based on research studies of transplant outcomes.
Other Factors in Determining a Match
To select the best possible donor or if there is more than one donor, the doctor will look at other factors such as the donor’s age, gender, blood type, size, health, number of pregnancies in a female donor or whether the donor tests positive for a common virus called CMV. All of these factors are known to affect the transplant outcome. For example, if a patient has more than one 10:10 match donor, the above donor factors would be used to choose the most appropriate donor. Favorable factors include donors who are younger, male or female and have not been pregnant, blood type matched, similarly sized or larger than the recipient, in good health, and without prior exposure to common viruses. However, in many cases, donors do not have to have all favorable factors. HLA matching remains the most important factor to select a donor.
Most Common Donor Types
Most patients will have one of the following donors selected by the testing and factors listed above.
Related donor, matched sibling donor: Matched sibling donors are full siblings who are a perfect match to the patient. Matched siblings will be fully HLA matched. If available, matched siblings are typically the most preferable donor for allogeneic stem cell transplantation. There is a 25% chance that a patient and a sibling will be a full match.
Matched unrelated donor: The National Marrow Donor Program (NMDP) facilitates searching for unrelated donors from the United States and abroad. Unrelated donors are also matched at 10 HLA genes. The most preferable matched unrelated donor is one who is a 10:10 match with the patient. At times, donors who are 9:10 may also be used.
Umbilical cord blood unit: Cord blood may also be used as the donor stem cells. Umbilical cord blood units are banked publicly and available for use. Matching is less stringent for cord blood. Umbilical cord blood units may be 4, 5, or 6:6 HLA matches with the patient. Umbilical cord blood units have the specific advantage of lower rates of graft versus host disease and the disadvantage of increased rate of graft failure and longer time to engraftment.
Related donor, haploidentical: A haploidentical donor is one who is typically a 50% match to the patient. Typically, each parent will be a haploidentical match to the patient. If other donors are not able to be identified, haploidentical parents may be acceptable stem cell donors. Advances in graft versus host disease prophylaxis have allowed haploidentical donors to be a good option for some patients.
Stem Cell Sources Used
Bone marrow stem cells: Bone marrow stem cells are harvested from the donor in the operating room in a process called bone marrow harvest. Donors are typically under general anesthesia for this procedure. Bone marrow stem cells are commonly used for pediatric stem cell transplants, though are also used for certain adult stem cell transplants. Bone marrow may be used from related donors including matched siblings, or from unrelated donors.
Peripheral blood stem cells: Stem cells may be collected from donors through a process called apheresis. Donors may have peripheral IVs placed and may have their blood filtered through a machine which is able to collect their stem cells. This process is generally well tolerated. Peripheral blood stem cells are commonly used for adult stem cell transplants, though may also be used for some pediatric stem cell transplants. Peripheral blood may be used from related donors including matched siblings, or from unrelated donors.
Umbilical cord blood stem cells: Cord blood units are collected publicly, frozen, and stored in umbilical cord blood banks. They can then be identified and used for stem cell transplantation if needed. Umbilical cord blood is typically from an unrelated donor.
Before a blood or marrow transplant it is important to make sure all of the organs are healthy and you/your child is free from infection. Blood tests, scans and other tests will be performed to check each organ system for its level of function and to look for potential sites of infection. It is also important to evaluate the underlying disease and ensure that you/your child is in remission or at the best point for a bone marrow transplant.
You/your child will undergo a thorough medical evaluation two to three weeks prior to admission. Your medical team will decide what studies need to be done. The evaluation may include some of the tests listed below:
Echocardiogram (Echo): This test is a type of ultrasound, it records the echoes of sounds sent through the heart. This test shows the size of the four chambers of your heart as well as how well the heart muscle contracts.
Pulmonary Function Test (PFT): This is usually done on kids who are over age 5 or 6 years old. The test measures your/your child’s lung capacity. You/your child will be asked to breathe into a mouth piece that is attached to a machine.
CT Scan (Sinuses/Chest): This is a computed tomography scan, which is a type of X-ray that takes pictures of your/your child’s body. It provides pictures of the sinuses and chest to evaluate you /your child for potential infections in these areas.
Dental Evaluation: You/your child will have a dental exam to make sure there are no hidden infections or abscesses or teeth that need pulled. If your child needs to have significant dental work, the transplant may need to be delayed.
Creatinine clearance: This is a test done to check how well your kidneys work. It can be done one of two ways. A collection of your urine for 24 hours, this can be done at home and brought in to the hospital the next day. Or a Renal scan can be performed on younger children who are not potty trained yet. A renal scan is an x-ray that takes pictures of your kidney and tells us how well they work.
Blood tests: Blood tests will be performed to evaluate the kidneys, liver function, to check for germs that cause infections during a bone marrow transplant, such as CMV (cytomegalovirus), Hepatitis, or HIV.
Depending on the type of transplant and your/your child’s condition, you /your child may have to undergo some additional test. These may include:
Brain Magnetic Resonance Imaging (MRI): An MRI scan uses magnets, rather that X-Rays, to produce more detailed images by sending radio waves into the body and then measures the response with a computer. The computer makes a picture or image. This is often used to look at the brain and spinal cord.
Audiogram: Is a test that measures hearing. Headphones and speakers are used to evaluate your/your child’s response to sound. The extent of the testing is based on age and the test usually last for about 1 hour. Parents may stay in the room during the testing.
Developmental/Neuropsychometric testing: These are special tests that are given by a Psychologist to determine cognitive (intellectual) and psychosocial abilities and milestones of your child. In addition, to age specific testing, parents are asked to respond to questions. It usually takes two 4 hour sessions to complete the entire testing. The information is useful to both parents, the health care team and your child’s teacher, to provide anticipatory guidance and support for learning.
Bone Marrow Aspirate and Biopsy: Cells are removed from the bone marrow. A bone marrow aspiration and biopsy usually take 20 to 30 minutes to complete. This test is painful so local anesthesia and sedation are utilized. These are often done in a special setting so your child can be monitored while receiving sedation. This is done for patients with leukemia or diseases that may go to the bone marrow or for patients whose bone marrow has failed.
Spinal tap/Lumbar Puncture: The test is done by inserting a needle between the backbones of the lower back called the lumbar spaces. A clear fluid called cerebrospinal fluid (CSF) surrounds the brain and spinal cord. A sample of this fluid is removed using a needle and is tested for cancerous cells or infection. Another name for spinal tap is a lumbar puncture. The procedure takes 15 to 30 minutes and patients may need to receive sedation to undergo this procedure.
If your child has cancer, there may be other scans done to determine the stage of your/your child’s disease prior to undergoing BMT. These will be the scans your child has had previously to monitor their disease.
Additional evaluation may be needed with other specialists. These specialists may include: Radiation Oncologist (for patients who will be receiving radiation as part of their bone marrow transplant conditioning regimen), Neurologist (specialist in the nervous system); Endocrinologist (specialist in hormonal glands); Pulmonologist (specialist for the lungs); Cardiologist (specialist for the heart) in addition to others.
While the pre-transplant work-up and evaluation is being completed, a tentative schedule is established for admission for transplant. This will vary depending on your/your child’s need for additional treatment prior to transplant and if an unrelated donor search is necessary.
Testing & Procedures
HLA testing to determine whether individuals are a good match only requires blood tests to be done. A bone marrow biopsy is not required. At the testing stage, the potential donor does not have to travel. Testing can be performed at the donor's closest hospital or laboratory, and the blood will be sent by courier to the transplant center. The BMT Coordinators will arrange for this. Potential donors, patients, and families need to be aware that HLA test results may take up to three weeks to process. It is also important to note that the patient and donor may still be a good match, even if they do not share the same blood type. Blood type and HLA type are completely different.
Preliminary Tests for Donors
All identified donors will need pre-collection diagnostic tests. These will include a screening blood test for hepatitis viruses and HIV (the AIDS virus), urine tests, and a medical history and physical examination by a physician. For adult donors, a chest X-ray and an electrocardiogram (ECG) are often done. Note that these tests can be done in the donor’s home town as long as the results are in English. Donors will typically need to be seen at a transplant center for pre-collection tests, however, this does not have to be the same transplant center where the stem cell transplant will take place. For donors having a bone marrow harvest, an anesthetist will also see the donor upon his/her arrival to review his/her medical history, conduct a physical examination and to discuss the method of anesthesia. General anesthesia is typically used.
The information on the website is intended to introduce you to some of the medical procedures and treatments which you/your child may receive when undergoing a hematopoietic progenitor cell transplant. The information on the website provides general guidelines but cannot replace the recommendations of your primary medical team. Specific patient care treatment options and procedures are the prerogative of each patient and their medical care team. You are encouraged to discuss any concerns or questions you have with your medical care team. Although every attempt has been made to post information that is clear and accurate, no guarantee is made to the reliability, completeness, relevancy, accuracy, or timeliness of the content. No liability is assumed by the Pediatric Blood and Marrow Transplant Consortium for any damages resulting from use or access to information posted on this website.