Finding a Donor
If you are going to have an allogeneic stem cell transplant, you will need a donor. For the transplant to be successful, the patient and the donor must have similar genetic markers on their cells.
What are they matching?
On the surface of your cells there are different sets of proteins. These proteins are like a fingerprint and allow your immune system to recognize cells that belong in your body and cells that do not (foreign). If your immune system finds a cell with the wrong "fingerprint", they coordinate your immune system to attack to destroy it.
Several different proteins, called human leukocyte antigens (HLA), play an important role in stem cell transplantation. These cells are found on the surface of all cells except red blood cells and play an important role in immunity (ability to fight infections) and transplant rejection. Your donor’s HLA type needs to match yours as closely as possible.
Finding a related donor
Typically, your biological siblings are tested first to see if they inherited the same HLA gene types as you. The HLA test is painless and requires only a blood sample or a swab of the inside of the potential donor’s cheeks.
Everyone inherits two sets of HLA genes from their biological parents: one set from their mother and a second set from their father.
Each sibling who has the same two biological parents has a 25 per cent chance of being a ‘perfect’ match. A ‘perfect match’, or a ‘10 out of 10 match’ means that they inherited the same two versions of the five HLA genes that are tested and most important for matching.
If no sibling is a perfect match, your parents, children or a sibling who is not a perfect match may be tested as a potential donor, or your transplant team may search for an unrelated donor.
You can find more information about being a related donor on the BMT Infonet website.
Haploidentical related donors
If none of your siblings is a perfect match, your doctor may suggest a haploidentical transplant. A haploidentical transplant is a transplant using cells from a related donor who only half matches your HLA type. This could be a parent, child or sibling.
Finding an unrelated donor
In Canada, the Canadian Blood Services Stem Cell Registry facilitates the recruitment of unrelated donors. Patients have access to an international registry with millions of potential adult donors.
Your transplant team can do a preliminary search of the World Marrow Donor Association (WMDA) registry to assess the likelihood of finding a donor for you. Donors with the same ethnic background as you are more likely to match you than those from a different ethnic background.
If potential donors are identified in the preliminary search, your transplant centre may then request a formal search.
Once the best donor is identified, the potential donor undergoes a complete medical evaluation to ensure they are healthy enough to donate and don’t have any medical problems that could pose a risk to you or themselves.
If more than one donor is found
If more than one potential donor is available, several other factors will help your doctor determine the most suitable donor.
- Younger donors are usually preferred over older donors.
- Donors who have not been exposed to cytomegalovirus (CMV) are preferable if you, too, have not been exposed to CMV.
- Some studies suggest that gender is important. Male patients transplanted with cells from a female, especially one who bore children, appear to have a higher risk of developing a complication after transplant called chronic GVHD.
Once a donor has been found and is considered healthy enough to donate stem cells, the transplant process can begin.
Finding a Donor
If you are going to have an allogeneic stem cell transplant, you will need a donor. For the transplant to be successful, the patient and the donor must have similar genetic markers on their cells. The Blood and Marrow Transplant (BMT) Program team will work with your physician to find the best available donor option for you.
You will have several tests done to make sure you are healthy enough to have the transplant. These tests give us information to help you decide whether to go ahead with the transplant.
These tests include:
Blood Tests
Your liver and kidney function can be measured by testing samples of your blood. Your blood will also be tested for signs of previous infections and exposure to certain viruses. We will also check your blood type and blood counts.
Bone Marrow Aspirate and Biopsy
You may have a bone marrow aspirate and possibly a biopsy to check the condition of your bone marrow and your disease status. During the aspiration, marrow and a small section of bony tissue is removed from your hip bone through a needle. You will be given a local anaesthetic to reduce discomfort.
Chest X-Ray
This test will show whether there are any problems with your lungs.
Electrocardiogram (EKG/ECG)
This test measures your heart’s electrical activity. It is painless and takes about 10 minutes to complete.
Echocardiogram (Heart Study)
This test measures how well your heart muscle works. It is an ultrasound of your heart. A gel will be placed on your chest and a wand will be moved over your skin to send high frequency sound waves to give a picture of the heart valves and chambers. You may feel a slight pressure as the wand is rubbed over the gel. This test will take about 40-60 minutes.
Pulmonary Function Test (Lung Function Test)
This test will tell us how well your lungs work. You will be asked to breathe into a machine which will measure how much air you breathe in and out. A blood sample may be taken from your ear lobe to measure the amount of oxygen and carbon dioxide in your blood.
CT scans
In some instances, such as to rule out infections or blood clots, you may need to have a CT scan done.
Dental assessment
You will be referred to the Victoria Hospital dentistry team for an assessment. They may recommend repair work or teeth removal to be completed before transplant to reduce the risk of infection.
Another consideration
Fertility: Having a stem cell transplant can make you unable to have children. Men may wish to think about sperm banking before starting treatment. Women may wish to think about fertility options such as embryo or egg cryopreservation. If you would like more information about fertility, speak to your hematologist or oncologist, the transplant clinic nurse or the social worker.
